Zeiss Optical Systems for the Microscope - Science-Info

General remarks Planapochromats 51Phase-contrast obiectives 52A few words on the working principle POLZ obiectives 54of the microscope4 UD Achromats 56Parfocal ization of objectives and eyepieces 10Appropriate selectionSpecial-pu rpose objectivesULTRAFLUARS5758of initial magnificationsJamin-Lebedeffof objectives and eyepieces 12 transmitted-light interferencequipment 59Field of view and viewing angle 14 Objectives for reflected-light microscopy 60Correction of aberrations16 EPIPLAN HD obiectives 61The cover glass and its importance forimage quality in the microscopeThe immersion method 20EPIPLAN oEPIPLAN POL objectives62636465ZEISS obiectivesEPIP PhoClassif ication of objectives23 Antiflex immersion objectives 68Achromats 25Planachromats 26 Photom icrog raph ic objectivesNEOFLUARS 27 LUMINARS with iris diaphragm 69Planapochromats27 Epi-LUMINARS 71ULTRAFLUARS 28Obiective mountsZEISS objectives for photomicrography29 EyepiecesC-type and Kpl eyepieces72LUMINARS 32 Eyepieces for spectacle wearers 73Eyepieces for micrometer disks 74Micrometer disks 75Object marker with diamond tip 76Intermediate systems changing36Stage micrometersPointer eyepieces7778MZEISS condensersEyepiece for stereomicroscopes42 Microprojectioneyepieces80B1Dark-f ield illumination 46 Special-purposeyepieces 82Grain-size disks according to ASTM Eand VDE h standards84I ntegrating micrometer disks86Double eyepiece with pointer 86Centering telescope, Klein magnifier,ctroscoIngsystems88NEOFLUARSCondensers89

General remarksA few words on the working principle lf objects or details are to be seen clearly,of the microscope a suff iciently large image must be formed onthe retina of the eye. A measure of the sizeof this image-which cannot be measure directly-is the so-called angle of view. In manycases this is so small that the desired claritycan no longer be achieved. To obtain greaterclearness, means must therefore be used toincrease the viewing angle and thus theimaoe formed on the retina.fhe simplest solution consists in approachingthe eye as closely to the object aspossible. This. however, is feasible only toa certain extent because of the limited abilityof the eye to accommodate. To overcomethis difficulty we have to avail ourselves oflenses or lens systems. The effect of such anauxiliary means is, in each case, that the objectlocated a short distance in front of theeye-or even an image of such an object-isimaged at a greater viewing angle and a sufficientdistance from the eye to allow observationwithout any particular stress on ourmechanism of accommodation.The aid usually employed for this purposeis an ordinary converging lens of sufficientlyshort focal length, which will form a magnif iedimage of an object located in its focal planeat a distance far enough for the eye lookingthrough the lens to view it without difficulty.The eyewillthen see the object under awiderviewing angle as if it were viewed from anormal distance. Such a lens is called amagnifier. lts magnification is defined as therelationship between the tangent functions ofthe two viewing angles, a certain value havingbeen adopted as the normal viewing distance,viz.250 mm. This is the so-calle distanceof distinct vision. Using this value, weobtain for the numerical value VL of the magnificationof a magnifier of focal length fL:,r, -250vL -f,

lf higher magnifications are required,simple lenses are no longer sufficient. In thiscase, the requirements to be made of imagequality can only be satisfied by lens combinations.However, the magnification whichcan be achieved in a single magnificationstage, as in a magnifier, is limited becausetechnical problems only allowthe focal lengthto be reduced to a certain degree:the lenseshave to be curved ever more steeply and theirdiameters thus become smaller and smaller.This results in difficulties not only in manufacturing,but primarily in using them: theviewing distance is greatly reduced, theimage brightness is low and the visual fieldsmall.These disadvantages can be overcome iftwo successive image-forming systems areused as is the case in the compound microscope:The first stage of image formation consistsof a lens system, the microscope objective,located close to the object, which formsa real and magnified aerial image of the object,usually at a certain distance from thelatter. The relationship between image sizeand object size, the scale of the image M,ni,is governed by optical laws and is representedby the relationship of the separationbetween the image and the primary focalpoint of the objective, which is called the"optical tube length t", and the objectivefocal length foui, viz.Mobi =fobiThe content of this aerial image formed bythe objective, i. e. the detail of fine objectstructures it contains, however, has nothingto do with the scale at which the objectivereproduces the object. On the contrary-asAbbel was the first to prove-it depends not

only on the wavelength of the light used forobservation, but primarily on the light-admittingproperties of the objective. These aredetermined by the aperture angle of the coneof rays from the pencil originating at the object,which is able to enter the instrumentthrough the aperture of the objective. Themeasure of this angle is-likewise sinceAbbe-the numerical value of the sine functionof half the aperture angle. lf the penciloriginating at the object does not passthrough air before it reaches the objective,but through another medium of different refractiveindex, the angle must be multipliedby this index. Because of its importance forimage formation in the microscope, Abbecoined the term numerical aperture for theproduct of the sine of half the apertureangle and refractive index. Thus if this rermis abbreviated N.A., as is customary in microscopy,and o inserted for half the apertureangle, then we haveN.A,:n.sinoWith regard to the magnified image formedby a microscope objective it must be notedthat two adjacent object details will only beseparated, or resolved as it is called in opticallanguage, if the expression)'>a >)'N.A.:-:2N.A.applies with regard to their separation d.Consequently, the magnitude of the separationd to be resolved is always between thelimits), I*-A- ano 2NAI I I ustration:llluminating cone made visible.The cone of light varies as a function of the numerical aperture.I Ernst Abbe (1840-1905), physicist and professor at Jena. From1867 worked for the ZEISS Optical Works. Became a Dartner inthe company in 1875. Pioneer of microscope construction. Eslablishedthe ZEISS Foundation.

10detail. In addition, the errors inherent to agreater or lesser degree in any image formedby the lenses have to be eliminated to suchan extent that the overall system guaranteesa largely unaberrated reproduction of resolvedimage detail.While-as we have seen-the resolvingpower at a given wavelength of light dependsexclusively on the objective, the image-formingproperties are determined jointty by theobjective and the eyepiece, although theprimary influence is the type of objective.The magnifying power is determined onthe one hand by the objective and the eyepiece,but on the other also bythe mechanicalsystem of the microscope connecting thetwo, because its Iength determines the opticaltube length. Since the demands made withregard to resolving power, magnifying powerand image-forming properties cannot besatisfied with a single objective and eyepiecesystem, the connecting element, the bodytube, must be designed so that the two componentscan be easily detached from it. Thisis why the lens elements of both the objectiveand the eyepiece are accommodated in special"mounts". The former have a standardthread by which they can be screwed into thelower end of the body tube. The simpler,tubular mounts of the eyepiece lenses areslipped from above into the suitably shapedeyepiece tube.Parfocalization of objectives and eyepieces To facilitate the exchange of objectives,so-called "objective changers" are usually. inserted between the objective and the bodytube. The location of the plane separaiingthe body tube from the objective on the onehand and the eyepiece on the other is determinedby practical considerations:The tube should always be in the sameposition in relation to the specimen.The image must remain in focus when

12excessively long or centering will become +oodifficult. A reasonable value has been foundto be 45 mm, which we have been using forall ou r transm itted-lig ht objective since 1950.The intermediate image distance ol theeyepiece should be chosen as short as possibleto allow eyepieces of short focal lengthalso to be parfocalized without difficulty.With our eyepieces it is 10 mm.The mechanical tube length should aboveall be chosen so that the microscope can bedimensioned to suit its purpose without becomingunwieldy. The mechanicaltube lengthof our microscopes is 160 mm.For the normal transmitted-light microscope,the combination of these three magnitudesresults in a distance of 195 mm betweenthe specimen and the aerial image.Object distance mechanical intermediate image objectto-imageof objective tube length plane of eyepiece distance45 mm 160 mm 10 mm 195 mmAppropriate selectionof inilial magnificationsof objectives and eyepiecesOnce the tube length has been fixed, thetotal magnification of the microscope onlydepends, in addition, on the focal lengths ofobjectives and eyepieces, i. e. the scale ofthe aerial image and the eyepiece magnification.The user of the microscope will find it ofadvantage if these two factors are chosen sothat a Iarge number of total magnificationscan be achieved with a minimum equipmentoutlay. Such a series can be considered aswell coordinated only if it satisfies the followingconditions:The relationship of every component inthe series with the one preceding it and theone following it should be of equal magnitude.It should be possible to obtain series withlarger increments by leaving componentswith smaller increments out of a basic series.

13The values of the different componentsshould be round figures or should at leastbe close enough to round figures to be expressedby them with sufficient accuracy.The series should be so established thatonce fixed for a power of ten it can beextended as desired by multiplying by 10,100, etc.These conditions are well satisfied by thedecimal geometric series on which the Germanlndustrial Standard DIN 323 is based.The working group on microscopy in thestandards committee of the German PrecisionEngineering and Optical lndustry hastherefore proposed that the R 10 standardseries from this standard be adooted as thebasis for a microscope magnification series.It is contained in the draft standard on microscopemagnifications, DIN 58,886, and iscomposed as follows:Standard Seriesl.tc t.o2.5 3.26.310 12.5 to 20 25 32 40 50 o,J 80100 125 160 200 250 320 400 500 630 8001000 1250 1600 2000 2500 3200 4000 etc.When deciding on the characteristicvalues of objectives and eyepieces on thebasis of such a series, the following pointsmust be taken into consideration:There should be 4 to 5 main objectiveswith the aid of which the range of total magnificationsrequired for practical work can becovered, since only this number of objectivescan be mounted on the conventional type ofobjective changer (revolving nosepieces).The values for the initial magnification ofthe objectives and eyepieces must also betaken from the above series. Only then is theadvantage of the standard series f ully utilized,viz. that the product of any two figures isagain a standard figure.

14In view of these considerations we havechosen the following magnification incrementsfor our objectives . Only in rare casesand in the case of special-purpose objectiveshave important reasons prompted certaindeviations.Series of initial magnifications of objectivesBasic series2.5 4 6.3 10 16 25 40 63 100Main series 2.5 6.3 16 40 100Simplified series 2.5 10 40 (100)(2.5\ 10 40 100Series of initial magnifications of eyepieces 4x 5x 6.3X 8X 10x 12.5x 16x 20x 25)

15the objective used-if necessary making al-Iowance for a factor due to body magnificationor an intermediate optical system.The field-of-view number and the eyepiecefocal length also serve to determine theviewing angle under which the eye sees theentire image. lf S is the field-of-view number,then the viewing angle w results from theexpression. w St9 2 z.f *,This viewing angle is also indicated in thedifferent eyepiece tables.All factors determining the magnifyingpower of the compound microscope and itsrelationship to the resolving power given bythe aperture of the objective (range of usefulmagnification) can be represented diagrammaticallyas is shown by the following exampleof a typical series of objectives andeyepieces.The horizontalines in the diagram representthe steps by which the total magnificationincreases in accordance with thestandard series, page 13. The solid linesfrom the lower right-hand corner to the upperleft-hand corner are guide lines for the objectives,the magnif ication and numericalaperture of which are indicated beside thelower end of the guide line. The guide linesfor the eyepieces are the dash-dotted onesrunning from the lower left-hand cornerto theupper right-hand corner. The eyepiecemagnification and the field-of-view numberare indicated beside their lower end. Theguide lines for the eyepieces intersecthoseof the objectives at the steps which indicatethe total magnification of the correspondingcombination. The colored frame limits therange of useful magnification as defined byAbbe.

and irs imporrance tJl';""?"JTlffi;16Correction of aberrations According to the laws of geometric optics,there is a considerable number of errorsinherent in the image formed by an opticallens. Of these, the following affect imagepoints even near the optical axis:spherical aberrationsine comalongitudinal chromatic aberrationchromatic difference of spherical aberration.Towards the edge of the field, the followingaberrations are increasingly evident:comaastigmatismcurvature of fielddistortionchromatic difference of magnification.It is impossible to correct all these aberrationsat once and completely. They canonly be more or less reduced, greateremphasis being placed on the reduction ofsome than others depending on the intendeduse of the optical system.The technical means required for the satisfactorycorrection of optical aberrationsdepend primarily on the degree of perfectiondesired; in addition, they depend on thedesired numerical aperture.Special attention must be paid to theeffect which the cover glass generally usedin the microscope for examining specimens by transmitted lighthas on image quality. This influence is clearlynoticeable with objectives of larger numericalaperture than 0.3 to 0.35. lt takes the form ofspherical overcorrection and must be compensatedby an appropriate residue of undercorrectionin the objective if the latter isdesigned for examining covered specimens.This is, of course, possible only if the overcorrectionintroduced by the cover glass isalways identical, and this is only the case ifthe cover glass has a certain thickness andrefractive index, and the specimen is in very

17Vt,n320025002000160012501000800630500400320250200160125100805010322520t612,5

18Cover-glass thickness with dry objectives Table 2close contact with the underside of the coverglass.Microscope objectives are normally correctedfor a cover glass thickness of. 0.17 mm.lf the cover glasses actually used deviatefrom this nominal thickness, they will producea more or less disturbing over- or undercorrection,depending on the numerical apertureof the objective employed. The followingtable indicates the amount of deviation fromnominal thickness which is tolerable withoutany noticeable loss of image quality.N.A. of objective Admissible deviationfrom nominalApproxirnate rangeof admissible cover-glass thicknessthickness of 0.17 mm (mm)0.08 - 0.3 0 -0.30.3 - 0.45 +0.07 0.1 - 0.240.45 - 0.55 +0.05 0.12 -0.220.55 - 0.65 + 0.03 0.14 -0.200.65 - 0.75 + 0.02 0.15 - 0.190.75 - 0.85 +0.01 0.16 - 0.180.85 - 0.95 + 0.005 0.165 - 0.175This table shows that with objectives ofvery high numerical aperture the optimumimage quality is achieved only if special careis taken to use only cover glasses of prescribedthickness and if the object detail onwhich the microscope is focused is in directcontact with the underside of the cover glass.However, this will be the case only veryseldom. Generally, there will be a more orless thick layer of mounting medium betweenthe focusing plane and the underside of thecover glass, which has about the same effecton the correction as if the thickness of thecover glass were increased by the sameamount. The "effective cover-glass thickness"is therefore composed of the actual

19cover-glass thickness and the aforementionedlayer of mounting medium between thefocusingplane and the underside of the coverglass. The resulting inaccuracy has promptedobjective manufacturers to use specialmounts for all objectives with which such fined ifferences matter. These so-cal Ied correctioncollars allow one lens element to be shiftedso that the over- or undercorrection due toa deviation of the cover-glass thicknessfrom the nominal value can be comoensated.For this purpose, the correction collar has aknurled ring wiih a graduation and index.The figures of the graduation (12...17...221indicate the cover-glass thickness in hundredthsof a millimeter. Optimum imagequality is obtained when the figure correspondingto the thickness of the cover glassused is opposite the index.ln general microscopic practice it will notbe possible to measure the effective coverglassthickness directly. lt is therefore necessaryto use indirect methods to determine thecorrect setting of the correction collar.1. The only method which can be used in all circumstancesand at the same time ensures the most accurate settinq of thecorrection collar, consists in measuring the effective cov-er-glassthickness with the aid of the microscooe:. .. Using a 40x, N.A. 0.65, 40X. N.A. 0.75 or 40y, N.A. 0.gSjective, the condenser is stopped down to half the ob-obiective9perture.and the microscope successively focused on the surlace_ottne cover gtass and the focusing plane with the aid ofthe fine adjustment. The corresponding readings of the fineadjustment are noted down. The difference be[ween the rwosettings gives the optical thickness of the cover qlass, which hasto be converted to the mechanically "effective thic:knesb" bv multiplyingit by a factor K. The latter'is preferably determinei onceand. for all by_ means of an experjment. Foa this purpose, thethickness D, of a few ordinary cover glasses is acctiratblv determinedby means of a. measuring-aid (micrometer, dial gage),whereupon thelr optical thjckness D, js measured with the mlcroscopeas described above. The desired factor K results from thetwo measurements:K=+It is not, as one might assume, identical with the refractiveindex ol the cover olass.Example: K iJto be determined with two cover qlasses ofdiflerent thickness. Measurements show the followino thicknesses.Cover glass No. 1Dl mm 0.161D, mm 0.102We thus obtain forDriD' = K 1.529No.2 (nD = 1.5288)0.2400.1521.572

202. With less, but still sufficient accuracy the experiencedmicroscopist will be able to adjust the correction collar by turningit until a fine, dark object detail is imaged with optimumconIrasl.It follows from the aforesaid that objectivesdesigned for use with cover-glas specimenscannot be employed for examininguncovered specimens. For use with uncoveredspecimens specially corrected obiectivesare available.I I I ustrati on :Rana, frog, blood smear.NEOFLUAR, 63x, 0.90 N.A., corr.Magnification 500xIn the upper micrographthe correction collar has been accurately setfor cover-glass thickness,in the lower the setting deviatesby 0.01 mm from the correct value.The immersion methodw,&An extremely efficient means of improvingthe image quality with objectives of highnumerical aperture is the principle of immersion.lt consists in using a liquid between thespecimen and the front surface of the objective,which if possible should have the sameoptical properties as the glass of the frontlens (homogeneous immersion). In accordancewith the formulad-N.A. n 'sin othis will also increase the resolving power by

21the factor n, an advantage which today isf requently considered as the primary purposeof immersion.Since an objective can be far better correctedfor homogeneous immersion than adry system of identical focal length and numericalaperture, it may also be of advantageto use the immersion method with systems oflonger focal length. This gives objectivespermitting a higher empty magnification andthus making it possible to cover a wide rangeof resultant magnifications by simple exchangeof eyepieces.Another advantage of the immersion methodis that neither the cover-glass surfacenor the front lens of the objective reflect anylight so that for critical work the image is ofconsiderably higher contrast than with anotherwise equivalent dry objective.Since the optical characteristics of theimmersion liquids have to be taken into accountin the computation of the objectives,similar to those of the cover glass, it isessential to use only the prescribed immersionoil. This is all the more important as theprinciple of rigorous homogeneity has beenabandoned with many of the highly developedimmersion objectives presently in use.Instead of the usual oil (refractive indexno [20o C] : 1.515), water (no: 1.333) orglycerin (no : 1.455) are occasionally usedas immersion media for special purposes.Water immersion is used for examining objectsin water. Glycerin is used if for somereason the objective front lens and the coverglass are made of amorphous quartz andapproximate homogeneity is desired.Objectives designed for homogeneousimmersion may be used with covered or uncoveredspecimens. The cover-glass thicknessis naturally of no importance with thesesystems. lt is different with present-day immersionobjectives, in which the principle of

22homogeneity has been abandoned. This pointshould be remembered if immersion objectivescomputed for covered specimens arealso employed for viewing smears which areleft uncovered to save trouble. This is normallythe case in the examination of bloodand bacteria smears. While the slight degradationof the image thus produced maystill be tolerable for routine work, the troubleof covering the specimen should definitelynot be shunned in critical work where full useis made of the high performance of the objective.lt is true that the lack of a cover glasscan be made up by other means, such as theuse of immersion oil of higher refractive index-no20oC : 1.52 instead of 1.515-or byincreasing the tube length, but who wants touse two different types of immersion oil andwhere can a microscope be found today inwhich the tube length can be increased up to25 mm ! Finally, cbjectives specially correctedfor uncovered specimens, as normally employedfor reflected-light work, may also beused for this purpose.

ZEISS objectives 23classification of objectives The different types of objectives aregenerally classified in accordance with thedegree to which their aberrations have beencorrected, their designation indicating chromaticcorrection first. This also automaticallyconstitutes a classification according to thetechnical means required for achieving theirrespective degrees of correction and hencetheir price categories.We distinguish between the following correctioncategories:ach romatic objectives,sem i-apoch romatic objectives,apoch romatic objectives.In their original form, all objectives inthese three categories exhibit field curvaturewhich increases considerably with decreasingfocal length. As long as they wereprimarily used for visual observation, thiswas not felt as a serious drawback, becauseany desired point in the field of view couldeasily be focused with the aid of the fine adjustment.However, since the techniques ofphotomicrography have assumed such importance,new types of objectives have had tobe developed in which the curvature of thefield is eliminated to a sufficient degree, inaddition to the other aberrations. Years ofcomputation were required to solve thisextraordinarily difficult problem in a satisfactorymanner. In 1938 our firm introducedthe first objectives giving a flat field,under the designation Planachromats. ln themeantime, countless improvements havebeen made in these objectives.As a result of this untiring work, a statehas now been reached which permits not onlyachromats but also apochromats to be madeas flat-field objectives. Thus the aforementionedthree categories of objectives aresupplemented by those of thePlanachromats and thePlanapochromats.

24These can be supplied both as dry objectivesand immersion objectives. There areobjectives corrected for the observation ofcover-glass specimens and others for usewith uncovered specimens. While the objectivescorrected for covered specimens aremounted and parfocalized so that they maybe used for transmitted-light work, the objectivesfor uncovered specimens are-with fewexceptions-designed for use in conjunctionwith vertical illuminators.To satisfy the special requirements whichhave to be made for observation by polarizedlight (strain-free components, provision foraccurate centering of objectives), objectivesin centering mounts are supplied, the opticalcomponents of which are manufactured andmounted with special precautions to guaranteecomplete freedom from strain (POL objectives).In principle, practically all objectives canbe equipped with phase plates for use of theZernike phase-contrast method. Our manufacturingprogram includes a wide choice ofsuch objectives.Our optical designers are today using themost advanced techniques and the latestglass types. They are constantly striving tofind the best for the microscope optics wemanufacture. the best that can be achievedwith the means presently at our disposal. Theuse of highly perfected glass types may, however,occasionally have the disadvantagethat a greater sensitivity to acids and watervapor is unavoidable. lt is obvious that thisapplies above allto the most highly correctedand therefore most expensive types of objective-ifonly in a few cases. Allowance for thisfact can be made by using only the less costlyobjectives for work with acids.A lens error which has a very importantinfluence on the satisfactory imaging of avisual field of a certain extension is the chro-

25matic difference of magnification. Ever sinceAbbe's time, this error has generally not beencorrected in the objective but by means of aneyepiece having an error of identical magnitudebut opposite direction. Such eyepiecesare called compensating eyepieces. ln orderthat a single series of eyepieces may be sufficient-afact which is today considered indispensablein the interests of easy operationof the microscope by less experienced personnel-allour objectives have the samelateral chromatic aberration. The fact thatthis is the case with all our objectives ensuresthat the user of our microscopes need notbother about which type of eyepiece to usefor a certain objective. Any of our eyepieceswill do. However, our objectives should neverbe combined with eyepieces of another makeif a more or less serious loss of image qualityis to be avoided.The different categories of objectives ared isti ngu ished by the fol Iowing characteristics :AchromatsAchromats are lens combinations in which,to keep the price down, only the back focaldistances for the colors blue and red of thespectrum have been made equal. This givesthe most favorable correction for the brightestregion of the spectrum. ln this region, sphericalaberration and sine coma as well asastigmatism have, of course, been eliminatedas far as necessary or feasible with the meansavailable at this price level. The residualchromatic aberration in this type of objectivecan be seen under oblique illumination asviolet and yellowish-green color f ringesaround dark object details. Under straightillumination and with the specimen out offocus, it appears as a weak violet cast abovethe plane of sharp focus and as a weak yellowish-greencast below that plane. Thesesecondary colors are all the more pronounced,the better the other aberrations

26have been corrected. Altogether, however,they are generally not bad enough to disturbvisual observation.The focal lengths of achromatic objectivesare chosen so that the upper limit ofusefulmagnification can be reached with eyepiecesof relatively low power. Eyepieces ofhigher magnification than 12.5x shouldtherefore not be used, or only in exceptionalcases, e. g. for measuring and counting.Achromatic objectives are employed forroutine work, for equipping teaching microscopesand for all applications in which criticalobservation is not required. lf due allowanceis made for their characteristics, theseobjectives may also be used for photomicrography,even for color photography. We nowonly manufacture achromats in simple mountsand exclusively for transmitted light.Planachromats Planachromats are objectives of improvedchromatic correction. in which the curvatureof field has been eliminated practically entirelyeven for the largest field of view encounteredin the microscope. This, of course,requires a much greater outlay which resultsin a correspondingly higher price. Due to theimportance of field flattening for viewingpolished specimens under vertical illumination,almost all our objectives for thistype of work are Planachromats. They arethen called EPIPLAN objectives and shouldbe used together with Kpl eyepieces.For reflecied-light microscopy we have1. EPIPLAN objectives for bright-field illumination,by which the illuminating light istransmitted to the specimen via a reflectingmeans (plane glass or prism) through the objective.The objective acts as its own condenser.2. EPIPLAN HD objectives for bright{ieldand dark-field illumination. Bright-field illuminationis attained as described above. In

27dark-field illumination the tight is guided pastthe objective and concentrated in the specimenplane by means of concentric mirrorsor concentric lens systems. The concentricmirrors or lens systems are combined withthe objective to form one unit.NEOFLUARS Using fluorite instead of crown glass, microscopeobjectives can be built which aredistinguished by considerably improved correctionof aberrations although they have thesame number of lens elements as achromaticobjectives. The design we use for"NEOFLUARS"ourand which can be tracedback to R. Winkel comes very close to thecorrection of apochromatic objectives. Onlysecondary color has not been completelyeliminated although it is far less noticeablethan with the achromats. lt is obvious that theIimited number of lens elements used in theNEOFLUARS does not allow a correction forfield curvature. However, the low number ofglass-to-air surfaces in these objectivesensures a minimum of flare so that they produceimages of surprisingly high contrast.The excellent correction of NEOFLUARSmakes it possible to achieve considerablyhigher numerical apertures than in achromaticobjectives. Thus the N.A. of NEOFLUARobjectives-insofar as they are dry systemsis15 to 30 o/o above that of normal achromatsof identicat focat tength (tabtes 8-10).NEOFLUARS may therefore be combinedy,'*#'*":","#",{J'fi5:?ilarly well suited for phase-contrast work.Planapochromats With the aid of special glass types, whichwere then new, and fluorite, Abbe was thefirst to succeed, in the eighteen-eighties, incomputing objectives of equal back focaldistance for more than two colors and, at thesame time, far-reaching correction of the

28Transmission of ULTRAFLUARSULTRAFLUARSother aberrations as well. Abbe announcedthis new type of objective, which he calledapochromat, on July 7, 1886. Ever since, ithas been continually improved and today itis so highly developed that further improvementappears hardly possible, all the more soas it now gives a perfectly flat field withoutsacrificing any of its other characteristics.Since this has become possible we onlymanufacture flat-field apochromats, which wecall "Planapochromats". Owing to the apochromaticcorrection of these objectives'residual chromatic aberration can no longerbe recognized in the image. lt is, of course,necessary to use suitable eyepieces whichcompensate for the chromatic difference ofmagnification.The numerical aperture of our Planapochromatshas been increased to a few percent above that of the NEOFLUAR objectives.They thus representhe ultimate in performancethat is possible today-and probablythat is possible at all. As a result, these objectivesare used whenever maximum resolutionis required for extremely critical work.It is obvious that they are superior to all othertypes of objective in color photomicrography.Planapochromats should always be combinedwith Kpl eyePieces.ULTRAFLUARS are special-purpose objectivesdesigned so that the ultraviolei lightis also used for image formation in the microscope.They must therefore contain onlymaterial the transmission of which is sufficientfor the desired range f rom 400 m,a downto about 2O0mp^ Glass cannot be used forthispurpose. Only amorphous quartz and fluoriteare suitable. Since for many years it seemedimpossible to achieve chromatic correctionevenjust for a small region of the spectrumwiththe aid of these two materials alone, socalled"Monochromats" were at first intro-

29Objectivemountsduced, which were corrected for only onewavelength. Only recently have our opticaldesigners accomplished the feat of computinga series of objectives of excellent chromaticcorrection over the very large spectralregion from 230 m4 to 700 m4. Since then wehave been making only one series of objectivesfor ultraviolet microscopy. We call themULTRAFLUARS. We do not manufacture anymonochromats or even reflecting objectives,because these offer no advantages overULTRAFLUARS, but only have disadvantages.Transillumination objectives have thestandard W 0.8"X1/zd" thread for screwinginto the revolving nosepiece or single nosepiece.The high-power systems, which maytouch the cover glass, are equipped withresilient mounts which give way if they knockagainsthe specimen. This guarantees adequateprotection of both the specimen andthe objective front lens. The mount of theimmersion objectives-except the achromats-can be locked in retracted position soas to facilitate application of the immersionliquid.In view of the Iarge number of objectiveswith different characteristics which we manufactureit has been found conveniento makethem differ externally as well, so that the userwill recognize aI a glance what type of objectivehe has before him. They are thereforeidentified by the color and finish of themount, as well as its engraving (see table 3).Fio u re:Cr-oss-section dlagram of Planapochromat, 100x,1.3 N.A., oil,with object and front lens protection.

30Objective mounts Table 3Objective typeChromium-plated ColorUpper part of mount lower part of en- Engravedbelt-polishe6blackPlanachromats black glossy white Plan. EPIPLANNEOFLUARS chromium-plated,belt-polishedbelt-polished black NEOFLUARPlanapochromats chromium-plated,white PlanapoglossyULTRAFLUARS glossyblack ULTRAFLUARlmmersion objectives Table 4lmmersion systems are distinguishedfrom dry objectives by a black or colored ringat the lower end of the mount. In addition, theimmersion medium indicated by the color ofthe ring is also identified by an abbreviationafter the objective data. The following colorsand abbreviated designaiions are used onimmersion objectives:lmmersionmediumoilWaterGlycerinMethylene iodideColorof ringblackwhiteorangeyellowDesignationOelWGlyzMethylenjodidApart from the trade mark, our objectivesare eng raved f irst of al I with a f igu re ind icatingthe scale at which the real intermediate imageis reproduced atthe object-to-image distancefixed for our microscopes, i. e. the initialmagnification (e. g. 25), then-after a strokethevalue of the numerical aperture (e. g. 45).Below these two figures there may be additionaldata indicating the mechanical tubelength or the cover-glass thickness for which

31the objectives are corrected, as well as theserial number.The mechanical tube length in all our microscopesis 160 mm. On objectives sensitiveto deviations from the prescribed cover-glassthickness, the cover-glass thickness for whichthey are corrected follows the figure 160 aftera stroke.lndications referring to cover-glass thicknesshave the following meaning:"0.17" the objective is sensitive to deviationsfrom a cover-glass thickness of0.17 mm.the objective may be used with orwithout cover glass."0"the objective should only be usedwithout a cover glass.Special objectives, e. g. those containingstrain-free lenses for polarized-light microscopy,phase-contrast objectives, etc., areidentified by the abbreviations listed in thefollowing table:Table 5Abbreviation MeaningPhlPh 2 (red)Ph3Pol (red)HDEpicorrected for use with uncovered specimensPhase-contrast objectivesUse annular diaphragm 1 IUse annular diaphragm 2 | of phase-contrast condenserUse annular diaphragm 3 JObjective for polarized-light microscopyObjective for reflected-light work using bright-field or dark{ield illuminationObjective for reflected-light microscopySince the engraving on the objectives isoften in a position where it cannot be seenonce these have been screwed into the microscope,our objectives have colored ringsat the lower end of the funnel, which arevisible in any position and indicate the initial

32magnification of the objective. This colorcode, which is independent of the type of objective,is explained in the following table.Color code for initial magnificationTable 6lnitialmagnification1X 2.5X 4X 6.3 x 8i10x 16x 25X 40x 63x 80/100xColorof ringo rang e.. briohtvellow - greendarkgreenbriqhtDIUEdark. , wnlteOIUEZEISS objectives for photomicrography In the compound microscope, the objectLUMINARSfields that can be recorded photomicrographicallyfor low-power work are of limitedsize, in the case of our instruments a maximum7. ..8 mm. This is due to the fact that itis possible neither to achieve a sufficientlysmall scale of reproduction in a compoundmicroscope, nor to magnify the portion of theaerial image covered by the eyepiece beyondthe limit imposed by the clear diameter ofthe tube. lf larger object fields are to bephotographed at small scales and with a flatfield, we may only use a single magnificationstage, i. e. an image of the specimen must beformed directly on a light-sensitivemulsionby means of an objective of suitable focallength. Where high image quality is required,specially developed systems are used thedesign of which is similar to that of photographiclenses. ln addition, it is advisable toemploy a camera of variable extension. Tocover a wide range of image scales, we needa series of such "photomicrographic objectives"with carefully selected focal-length increments.These increments depend on thedegree to which the camera extension can bevaried. Of course the extension is alwayslimited.We manufacture such photomicrographicobjectives under the designaiion LUMINARS.

33Accessories are available which allowthese objectives to be used on our largecamera microscope ULTRAPHOT, which canbe equipped for any type of microscopic andphotomicrographic work, as well as on ourPHOTOMICROSCOPE and the UNIVERSALresearch microscope. For further details, seethe operating instructions for these instruments.LUMINARS are always used without eyepieces.The shorter focal lengths (16, 25 and40 mm) may occasionally also be combinedwith eyepieces and used like ordinary microscopeobjectives. In this case, however, eyepiecesmust be chosen to match the correctionof the LUMINARS. Suitable types are theeyepieces of our stereomicroscopes and C-type eyepieces.

ZEISS eyepieces 34Types of eyepieceAs was mentioned in the introduction(page B), the eyepiece is designed to presentto the eye the object detail resolved by theobjective and contained in the real intermediateimage under a viewing angle whichis sufficiently large for easy recognition. Thisalone could be achieved with a simple converginglens, but no influence could beexerted on aberrations. lf this is desired,such single-element eyepieces will have tobe replaced by more complex systems.In practice, however, these can be madeonly with relatively short focal Iengths, becauseon the one hand their diameterincreases sharply with growing foeal length,while on the other the exit pupil of the microscope-i.e. the image of the objective apertureformed by the eyepiece, which representsthe plane where the observer's eyepupil must be located-is moved to an inconvenientlylong distance away from the eyepiecelens. Both these drawbacks are eliminatedby constructing the eyepieces f rom twomore or less widely spaced components.one of which is located near the aerial image.Here it affects primarily the imaging of thepupil, while the second component takesover the eyepiece function proper, viz. thatof magnifying. The first component is calledthe "collective or field lens", the second the"eye lens". The field lens may be locatedbefore, in or behind the real intermediateimage. lf it lies before the aerial image, itwill reduce the latter by a certain degree andshift it towards the objective. Eyepieces ofthis type are called Huygenian eyepieces. lfthe field lens is located behind the real intermediateimage, then, of course, it does notmodify the latter. This is particularly favorablefor the purpose of measurement with theaid of micrometer disks arranged in the imageplane. Eyepieces of this type are calledRamsden eyepieces.

35Huygenian eyepieces result in a shorteroverall length of the microscope than eyepiecesof the Ramsden type. With short focallengths, however, the latter type allows theexit pupil to be located further away from theeye lens. This is why eyepieces of long focallength are usually designed on the Huygensprinciple, those of short focal length on theRamsden principle. The two componentsconsist of single elements only in the simplesttypes of eyepiece. Several elements are invariablyrequired per component if any influenceis to be exerted on the aberrations ofthe eyepiece itself or the residual errors inthe image produced by the objective. Thus ithas been general practice ever since the timeof Abbe to compensate for a rather troublesomeerror frequently exhibited by the objectiveimage and difficult as well as costlyto correct in the objective-the chromaticdifference of magnification-by using eyepieceswhich exhibit the same but oppositeaberration. In addition, attempts have occasionallybeen made to reduce field curvatureby means of the eyepiece. Eyepieces compensatingfor lateral chromatic aberration areknown as compensating eyepieces.To facilitate the use of our microscopes,we have computed all our objectives so thatthe chromatic difference of magnification inthe real intermediate image they produce isalways the same. We can therefore be contentto supply compensating eyepieces whichmake up for this degree of lateral chromaticaberration. This matching of objective andeyepiece correction, introduced in the interestsof our customers, is ihe reason why wehave to warn our customers against usingeyepieces of other manufacture with our objectives.The eyepieces for our stereomicroscopes,however, are not designed on the principleexplained above. They have no compensat-

36ing effeci, because in stereomicroscopes theoptical systems of the first magnificationstage are also free from lateral chromaticaberration. These eyepieces therefore cannotbe combined with the usual microscope objectives.Intermediate systems changingthe magnification During practical use of the microscope,a change of magnification by means ofchanging eyepieces is frequently consideredinconvenient and troublesome, because iheeyepieces not being used at the moment aredetached parts which may get lost ordamaged. To counter this disadvantage'magnification-changing systems have beeninserted between the objective and the eyepieceof the microscope. These may eitherbe designed for a stepwise change of magnification-whichwould correspond to a changeof eyepieces-or as continuously variablesystems. ln the latter, however, a more orless noticeable loss of image quality is unavoidable.We have therefore adopted thesystem of changing the magnification bysteps.lf only two alternative magnifications arerequired-which is generally considered sufficientfor teaching and laboratory microscopesused for routine work, for instancethenthe magnification changer may be used.This is a two-component system mounted sothat it can be inserted into the limb top of ourSTANDARD microscopes (STANDARD K' Ror WL). For this purpose the limb top isequipped with a spindle which can be rotatedthrough 90o and on which the magnificationchanger is secured by means of a coaxialscrew. This arrangement offers the advantagethat the magnification changer is normallyfirmly attached to the microscope, butcan be removed if necessarY.The following magnification changers areavailable:

370.8x;1x, 1x:1.6x, 1xZ2x (seeSection on field-of-view number and size ofobject field).When the magnification changer is set inthe proper position, the total magnificationcomputed from the initial magnifications ofobjective and eyepiece will be changed bythe corresponding factor.lf a rapid change of magnification in morethan two steps is desired, it is necessary toemploy a more complicated optical systemsuch as that contained in our OPTOVAR.Here the aerial image produced by the objectiveis first shifted to infinity by means ofa lower Telan lens of negative power. Thisimage is then viewed through a telescopesystem mounted above it. In the presentcase, the telescope system consists of anupper Telan lens of positive power mountedat the lower end of the tube and representingthe telescope objective, and the usual microscopeeyepiece. The two Telan lenses areheld by the upper and lower walls of a cylindricalhousing. The latter is designed so thatsmall Galilean telescopes can be inserted inthe space between the two Telan lenses. Forthis purpose, the telescopes are mounted ona revolving disk which can be controlled fromthe outside. The magnifying factors to beachieved are identical with the magnificationof the telescope systems. Apart from thefactor 1, which is effective if no telescope isin the light path, the OPTOVAR can be set for1.25x, 1.6 x and 2X or 0.8 x , 1.25x and 1.6 xmagnification with the aid of telescopes. Inaddition, another system can be moved intothe light path, which has the effect of aBertrand lens and permits the exit pupil ofthe objective to be viewed, for instance forobserving interference patterns, for centeringthe annular diaphragm in relation to thephase plate annulus in phase work, or forchecking the stopping down of the objective.

38This image-forming system for pupil observationmay also be used to advantage forproducing an only slightly magnified imageof the specimen, if it is desired to scan thespecimen for general orientation. ln this caseits magnificaiion factor is approx. 1.25.Intermediate magnification-changing systemsare listed in table 36 on page 88.Field-of-view number and size of object fieldMagnification-changing systems are aconvenient means of varying the size of theobject field covered for a certain field-ofviewnumber of the eyepiece without changingany mechanical dimensions of the microscope.lf the scale of the real intermediateimage is increased by means of such an intermediatesystem, a smaller object field will becovered. On the other hand, if the scale ofthe real intermediate image is reduced, theobjeci field will, of course, be larger' Thelatter is undoubtedly an advantage in allcases where many specimens have to bescanned. The only drawback is that the totalmagnification is reduced by the same factorby which the scale of the intermediate imageis changed. This disadvantage, though, caneasily be offset by a higher-power eyepiecewhich should, however, have the same fieldof-viewnumber as the one originally used.An example may serve to illustrate this:Combining a 10x objective and a 10xeyepiece with a field-of-view number of 16,an object field S of 16:10:1.6 mm will becovered under a total magnif ication of 100 X 'Inserting an intermediate system with afactor of 0.8 will increase the object field by-the reciprocal factor, since we have16 16=10.0€: B:zmm'lf we wish the total magnif ication to remainunchanged, instead of the 10x eyepiece we

39shall have to use an eyepiec"ffi = 12.5xwhich also has a field-of-view number of 16.Further magnification of the object field ispossible if eyepieces with increased field-ofviewnumbers, so-called wide-angle eyepieces,are employed. Substituting 10X or12.5x wide-angle eyepieces with a field-ofviewnumber o120 for the ordinary eyepieces,the above example can be written as follows:Without intermediate svstem20S =*:2 mm.IUWith 0.8 X intermediate svstem20"-10'0.8- :2.5 mm.In other words, the same object field iscovered under 100X total magnification as ifa 10X eyepiece with a field-of-view numberof 25 were used.Wide-angle eyepieces have been developedfor the observation of larger fieldsof-view.The following table lists the eyepiecesand their field-of-view numbers. The*image diameter given in the third column isbased on the conventional object distance of250 mm. lt is the product of the field-of-viewnumber and the eyepiece magnification.Table 7KplField-of-viewWide-angleyepiece number lmage diameter*12.5x 250 mm16X to 256 mmMounts and identification of eyepiecesAs is usual, the lenses of the eyepiecesystems are housed in relatively simplemounts. These in turn are contained in a tubefitting into the upper end of the microscopelube with the eye lens at the top and the field

40lens at the bottom. The mount of the eye lensis designed so that its projecting edge maybe gripped. The field lens is either locatedright in the eyepiece tube or likewise containedin a special mounting ring. The eyepiecetube or mounting ring has a femalethread of M 22X 0.5 into which light filters orother accessories may be screwed, as required.The outside diameter of the eyepieces isstandardized. This standard diameter istraditional in the normal microscope. lt is23.2 mm. In our stereomicroscopes a standarddiameter of 30 mm has been adopted. lnaddition, the diameter of the eye-lens mountof all our eyepieces conforms to the GermanDIN Standard 58,881 to facilitate the attachmentof accessories. Consequently, the eyelensmount diameter of all our eyepieces is28 mm.As is the general practice today, themagnification of the eyepieces is indicatedby a figure followed by " x ". Letters beforethe magnification mark the type of eyepiece.Since we manufacture only compensatingeyepieces, such an identification would normallybe superfluous. However, our eyepiecesof higher power are so designed thatthey produce a flat field, which is not necessaryfor the low-power systems. The latterare therefore marked C (compensating eyepieces)to distinguish them from the formermarked Kpl (compensating f lat-field eyepieces).The fact that the eyepieces are used toview a real image may be utilized to make asharp image of a reticule, graduation andother figures or pointers visible together withthis object image. These figures are engravedon glass plates (micrometer disks)which are inserted in the diaphragm plane ofthe eyepieces. However, since they will notnecessarily be seen sharply with normal eye-

41pieces, above all if the eye of the observer isnot free from visual defects, eyepieces with afocusing eye lens are used for this purpose.In addition, these eyepieces are designed sothat the micrometer disk can be easily,insertedand will be centered once it is inposition. The micrometer disks normallysupplied by us are Iisted on page 75.For polarized-light microscopy the crosshairsmarking the center of rotation of thestage must be very accurately centered.Since this cannot be achieved by the mereinsertion of crosshair disks, we manufacturespecial eyepieces with accurately adjustedcrosshairs or crosshair micrometer disks forthis purpose.For critical work, partly for very specialmeasuring or counting problems, we alsomanufacture a great variety of specialpurposeeyepieces which are listed after theordinary eyepieces.

ZEISS condensers 42ln microscopy self-luminous objects arerarely encountered, in fact only in fluorescentwork. In general, the objects to be examinedunder the microscope must be suitably illuminatedto allow their details to be imagedand viewed. Either incident or transmittedlight may be used for illumination, and in bothcases either the bright-field or the dark{ieldmethod may be employed. In the former, animage of the light source is formed in the objectiveaperture, while in the latter this is notthe case.With a perfect bright-field illuminator theaforementioned source image should fill theobjective aperture completely, because onlythen can the full aperture of the objective beutilized, if necessary. In addition, the objectfield reproduced should, of course, be completelyand evenly illuminated.When using high-aperture objectives, asource image of sufficient size can beachieved only with very large light sources.However, since the size of the light sourcesgenerally used today is limited, it must bemagnified by optical means. This is donewith the aid of a lens system located near thespecimen, the so-called condenser.The light source to be magnified must bebrought as close to the focal plane of ihecondenser as possible so that its magnifiedimage will be produced at a sufficient distancefrom ihe specimen. Otherwise theangle of incidence of the pencils of rays illuminatingthe object points will vary greatly inthe center and the outer field, thus producingincreasingly oblique illumination iowards theedge of the image so that the image characterwill no longer be homogeneous. Sinceit is not normally possible to locate a lightsource in the condenser focal plane due tothe heat it generates, the source is arrangedat an appropriate distance from the microscopeand a source image filling the con-

43denser aperture is formed in the condenserfocal plane with the aid of another lenssystem, the lamp condenser. This offers thefollowing additional advantages :The effective area of this image can bereduced by means of an iris diaphragm, whichis a convenient means of controlling the illuminatingaperture. Such an aperture iris ispractically always permanently attached tothe condenser.It is easy to achieve a very homogeneousiilumination of the object field reproducedby adjusting the condenser so that it forms asharp image of the homogeneous illuminatedaperture of the lamp condenser on the specimen.An iris diaphragm in this plane (lampfield stop) makes it possible to match the sizeof the illuminated field with that of the fieldimaged (Kiihler's method of illumination).In accordance with these general observations,a condenser has two functions in aneconomic bright-field illuminating setup:1. The condenser must be capable of producingcones of rays for illuminating the objectpoints, the axes (principal rays) of whichshould as far as possible be parallel and perpendicularto the specimen plane and whoseaperture can in certain cases be as large asthe aperture of the objective employed.2. The condenser should form a high-qualityimage of the lamp field stop in the specimenplane.To satisfy the first condition, a universallyapplicable condenser would have to have thehighest numerical aperture occurring withthe objectives used (1.3-1.4). However, sucha high illuminating aperture is actually usedonly in rare cases in microscopic practice. Infact, to increase image contrasthe illuminatingaperture should be smaller than the objectiveaperture. Experience has shown thateven in the case of immersion objectives withthe extremely high aperture of N.A. !1.4 an

44illuminating aperture of less than 1.0 isgenerally sufficient so that an N.A. 0.9 condenserwill do in the great rnajority of cases'This offers the following advantages:The correction of the condenser can beimproved without increasing its cost.The focal length and obiect distance ofthe condenser can be increased.As a result, the condenser diaphragm canmore easily be arranged in the correct position,in the focal plane. The front lens neednot be connected to the specimen slide bymeans of an immersion liquid.For reasons of price, condensers aregenerally corrected only as far as is possibleat minimum expense. Especially when usedwith higher apertures, it is therefore very difficultto achieve a satisfactory image of thelamp field stop with most condensers due totheir spherical and chromatic aberrations' Inorder to obtain a homogeneously illuminatedobject field the lamp field stop must beopened further than would normally benecessary. However, this is of no importanceas long as image contrast is not impaired.For critical work and in conjunction withhigh-performance objectives we recommendthat corrected condensers be used, which areavailable in the form of achromatic-aplanaticcondensers.With a lamp field stop of given diameter,a condenser of a certain focal length willonly illuminate an object field of a certainsize. lt is impossible to design condenserssuited for illuminating all the apertures andfields of view used in practice. This can beachieved only if-as with the objectives-condensersof different focal length are employed.Many condensers are therefore designedso that a relatively short-focus condensercan be converted into a condenser oflonger focal length and lower maximum apertureby removing its front lens or a front

45component.For this purpose the front lens is eitherunscrewed or, where this is technically feasible,swung out of the light path.All condensers are provided with themechanical fittings required for their use.The extent and design of these are indicatedin the following tables.The type of mount used to attach the condenserto the microscope depends on thetype of illuminator employed.lf the light of a separate illuminator isreflected into the condenser by means of amirror or if an integral illuminator with a sufficientlylarge radiant field is available (e. g.low-voltage base iliuminator or on-base illuminator),the condenser need not be centerable.With our microscopes, the simplest designconsists of a condenser sleeve mountedunderneath the microscope stage, into whichthe condenser is inserted.When the condenser must be movable inthe axial direction, however, it is mounted ona rack-and-pinion condenser carrier.In all our large microscopes (STANDARD,WL, UNIVERSAL, PHOTOMICROSCOPE andULTRAPHOT) the low-voltage illuminatornormally used as light source is permanentlyattached to the microscope.To allow the aforementioned illuminatingtechniques to be employed with sufficient accuracy,a device had to be incorporated inthe illuminating system with the aid of whichthe image of the lamp field stop formed in thespecimen plane could be centered in relationto the field reproduced by the microscope.We thus provided for a displacement of thecondenser by means of two centering screwson the condenser carrier, which act againstthe force of a spring. This device also servesto hold the condenser which is inserted intoit with a heat-treate dovetail ring. The con-

46denser can here in any case be axially displacedwith the aid of the condenser carrierto allow the image of the lamp field stop to befocused in the specimen plane.Z-type condensers are used with the condensercarriers.Dark-field illuminationlf dark-field illumination is used, the lightfrom the condenser does not enter the objectivedirectly. Only the light diffracted bythe specimen (in the case of incident illumination,the light reflected by the specimen)enters the objective and forms the image. Asa result, the areas in the field of view whichcontain no object structures remain dark.With dark-field illumination, the specimenis actually illuminated by a hollow cone oflight, the lowest aperture (interior limit ofaperture) of which is larger than the numericalaperture of the viewing objective.Dark-field illumination requires powerfullight sources and special condensers. lmmersionobjectives of higher numerical aperturethan 1 must be equipped with an iris diaphragmto allow their aperture to be reduced.With fully open iris diaphragm these objectivesare employed for bri g ht-f ield i | | u m i nation.Phase-contrast objectives are unsuitable fordarkjield observation.Dark-field UltracondenserDry dark{ield condenser

STANDARD WL research microscope wjth 6 v, 1S w integral illuminator,pancratic condenser, Planachromats, OPTOVAR and Kp'i wide-angle eyepieces47

Survey of optical systems 48Objectives forthetransm itted-l ight m icroscopeAchromats Table 8Desig nati o nln it ialmagnrficationN.A.FocalI engthmmWorking Cover-glassdistance?) thickness Catalogmm mm No.O Achromat,3.2x,0.07N.A. 3.2x 0.07 34.9 30 460100Achromat, 6.3x, 0.16 N.A. 6.5x 0.16 24.4 10.3 460300O Achromat,10x,0.22 N.A. 10.2x 0.22 16.7 5.0 460400Achromat. 16x. 0.32 N.A. 16.2x 0.32 10.8 3.5 460500Achromat, 25x, 0.45 N.A. 25.4x 0.45 7.0 1.0 0.17 460600O Achromat,40x,0.65N.A. 40.8x 0.65 4.5 0.47 0j7 460700Achromat, 63x, 0.80 N.A. 63.3x 0.80 3.0 0j4 0j7 460800Achromat, 40x, 0.75 N.A., waterl ) 40.4x 0.75 4.6 1.6 0.17 461702Achromat, 40x, 0.85 N.A., oil 40.0x 0.85 4.6 0.35 0j7 461706Achromat, 40x, 0.85 N.A., oil 39.2x 0.85 4.7 0.35 1.5 461708O Achromat 100x, 1.25 N.A., oil 98.8x 1.25 1.9 0.09 0j7 461900Achromat, 100x, 1.25 N.A., oil, with iris3) 98.8x 1.25 1.9 0.09 0.17 4619061) For Achromat, 40x, 0.75 N.A., water, a clip-on cap 461790 is supplied.,) The working distance is the clear distance between the front lens of the objective used and the specimen (upper surface of covetg lass).3) Objective with iris for stopping down the aperture in dark-field work.4) Objective with correction collar can be used for cover-glasses with thickness from 1.1 to 1.5 mm.5) Special objective, e. 9., for STANDARD UPL, for work with specimen in thick-walled chambers.

49Planachromats Table 9DesignationIn itialmagnificationN.AFocallengthmmWorking Cover-gd istance,) th icknessmm mmlassCatalogNo.* Planachromat, 2.5x,0.8 N.A. 2.6x 0.08 54.5 8.7* Planachromat 6.3x, 0.16 N.A. 6.26x 0.16 27j 4.9 460310O Planachromat, tOx, OZZ trt* 10.0x 0.22 15.8 4.8 460410f Planachromat, 16x, 0.35 N.A. 16.1x 0.35 10.4 2.7 460510Planach rom at, 25x, 0.45 N.A. 0.45 7.0 1.4 0.17 460610O* Planachromat, 40x, 0.65 l{A 40.8x 0.65 4.13 0.7 0.17 460710LD-PIanachromat, 40x, 0.60 N.A., corr.o; 3g.9x 0 4.1 1.1-'1.5460715s)f Planachromat 100x, 1.25 N.A., oit-100-6x T .60 1.5.% 1.660J90.17 461910Planachromat, 100x, 1.25 with N.A., iris3) oil,100.6x 1.25 1.660.09 0.17 461916Generally recommended for a series oJO four objectives+ five objectives

50NEOFLUARS Table 10ln ltia Imag n i-flcati onN.AFocalI engthmmWorking Cover-glassdistancer) thicknessmm mmCatalogNo.+ NEOFLUAR. 6.3x. 0.20 N.A. 6.4x 0.20 23.6 10.8 46ffi24NEOFLUAR, 10x, 0.30 N.A. 10.2x 0.30 16.4 4.0 460420+ NEOFLUAR, 16x, 0.40 N.A. 16.1x 0.40 10.8 0.9 0.17 460520NEOFLUAR, 25x, 0.60 N.A. 0.60 7.1 0.54 0.17 460620+ NEOFLUAR. 40x. 0.75 N.A. 40.5x 0.75 4.5 0.33 0.17 460720Plan-NEOFLUAR, 63x, 0.90 N.A.,corr.4) 62.9x 0.90 2.7 0.09 0.11-0.23460812-9903NEOFLUAR, 63x, 1.25 N.A., oil 62.6x 1.25 2,8 0.65 0j7 461820+ NEOFLUAR, 100x, 1.30 N.A., oil 100.0x 1.25 1.92 0.24 0j7 461920

51Planapochromats Table 11Desig nati o nlnitialmagnrficationN.AFocal Working Cover-glasslength distancer) ticknessmm mm mmCatalogNo.Pianapochromat, 4x, 0.16 N.A. 4.1x 0.16 35.1 2.5 460240Planapochromat, 1Oxo 0.32 N.A. 10.0x 0.32 14.6 0.35 0.17 460440Planapochromat, 25x, 0.65 N.A. 25.3x 0.65 6.3 0j4 0.17 460640Planapochromat 40x, 0.95 N.A., corr.4\ 40.4x 0.95 4.25 0.09 0.11-0.23460742Planapochromat, 40x, 1.0 N.A., oil,with iris3) 100.2x t.J 1.630.09 0.17 461946Planapochromat, 63x, 1.4 N.A., oil 62.1x 1.4 2.57 0.09 0.17 461840Planapochromat, 100x, 1.3 N.A., oil, 100.2x 1.3 1.630.09 0.17 461940Planapochromat, 100x, 1.3 N.A., oil,with iris3) 40.1x 1 .0 4.05 0.22 0.17 461746f) The working distance is the clear distance between the front lens of the objective used and the specimen (upper surface of coverglass).,) Objective with iris for stopping down the aperture in dark-fleld work.') uolecllve wiln correctlon collar can be used for cover-glasses with thickness from 0.11 to 0.23 mm.

52Phase-contrast objectivesThese objectives contain an annularphase plate in which phase shift and absorptionare matched so that optimum images willbe obtained with the majority of specimensfor which the phase-contrast technique canbe used to advantage. For special problems,objectives with specially matched absorptioncan be made to order. Details will be suppliedon request.lf phase-contrast objectives are used forbright-field work, a more or less noticeablebut generally hardly disturbing loss of contrastmust be expected, depending on theobjective type chosen. This effectwill be leastnoticeable with the Ph NEOFLUARS andPlanapochromats. For dark-field observationphase-contrast objectives are generally notto be recommended.

53Phase-contrast objectives Table 12Desi gnati onInitialmagnrficationN.A.FocaltengthmmWorking Cover-g I assd istance th icknessmm mmCatalogNo.Achromat, 10x,0.22 N.A.. Ph 1 10.2x 0.22 167 5.0 460401Achromat, 40x,0.65 N.A., Ph2 40.8x 0.65 4.5 0.47 0.17 460701Achromat, 40x,0.75 N.A., water, 40.4x 0.75 4.6 1.6 0.17 461703Ph2Achromat, 40x,0.85 N.A., oil. Ph3 39.2x 0.85 4.7 0.35 1.5 461709Achromat, 100x,1.25 N.A., oit, Ph3 98.8x 1.25 1.9 0.09 0.17 461901Planachromat, 25x,0,45 N.A., Ph2 25.2x 0.45 7.0 1.4 0.17 460611LD-Planachromat, 40x,0.60 N.A., corr., 39.9x 0.60 4.1 1.5 1.1-1.5 460716.Ph2Planachromat, 40x, 0.65 N.A., Ph 2 40.8x 0.65 4j3 0.7 0.17 460711Planachromat, 63x,0.90 N.A., corr., 63.4x 0.90 2.7 0.09 0j7 460813Ph3Planachromat, 100x, 1.25 N.A., oit, ph3 100.6x 1.25 1.660.09 0.17 461911NEOFLUAR, 16x,0.40 N.A., Ph2 16.1x 0.40 10.8 0.9 0.17 460521NEOFLUAR. 25x,0.60 N.A., Ph2 25.2x 0.60 7.1 0.54 0.17 460621NEOFLUAR. 40x,0.75 N.A., Ph2 40.5x 0.75 4.5 0.33 0.17 460721Plan-NEOFLUAR,63x,0.90 N.A., corr., 62.gx 0.90 2.7 0.09 0.11-0.23460813 _ 9903Ph3NEOFLUAR, 63x,1.25 N.A., oil, Ph3 62.6x 1.25 2.8 0.65 0.17 461821NEOFLUAR. 100x, 1 .30 N.A., oit, Ph 3 100.2x 1 .25 1.920.24 0.17 461921Planapochromai,25x,0.65 N.A., Ph2 25.3x 0.65 6.3 0j4 0.17 460641Planapochromat,40x,0.95 N.A., corr., 40.4x 0.95 4.250.09 0.11-0.23 460743Ph3Planapochromat, 40x, 1.0 N.A., oil, 40.1x 1.0 4.050.22 0.17 461747with iris, ph3Planapochromat, 63x,1.4 N.A., oil, ph3 AZ.lx@ 461841Planapochromat, 100x, 1 .30 N.A., oil, ph 3 100.2x 1 a- Special objective, e' 9., for STANDARD UPL, for work with specimens in thick-walled cnamoers.

54POLZ objectivesfor polarized-light microscopyThe objectives listed below are strain-freeand have centering mounts.Table 13Desig nati onln itialmagnificationFocal Workinglength distanceN.A. mm mmthicknessmmCatalogNo.O*Planachromat, 2.5x, 0.08 N.A., POL Z 2.6x 0.08 54.5 8.7 460'118Of Achromat, 10x.0.22 N.A.. POLZ 10.2x 0.22 16.7 5.0 460408-F NEOFLUAR, 25x, 0.60 N.A., POL Z 25.2x 0.60 7.1 0.54 0j7 460628O*Achromat, 40x,0.85 N.A., POLZ 39.4x 0.85 4.7 0.36 0j7 460708NEOFLUAR, 63x,0.90 N.A., POLZ 63.3x 0.90 3.0 0.12 0j7 460828O*Achromat, 100x, 1.25 N.A., oil, POLZ 98.8x 1.25 1.9 0.09 0j7 461908Generally recommended for a series ofO four objectives+ five objectives

55UD Achromats UD achromats are objectives specially designedfor use with the universal rotary stage.This aid for spatial orientation of the specimenis primarily used in polarized-liEht microscopy.The objectives are attached to thepolarizingwmicroscope with the aid of a centerableobjective changer"The initial magnification and numericalaperture indicated on the UD achromats holdfor use in conjunction with hemispheres witha refractive index of 1.555. lf the objectivesare suited for "conoscopic" observation, theyare marked "C". Under orthoscopic observation,the extinction position of a crysial canbe recognized if the aperture of the objectiveis reduced. This is why two funnel stops aresupplied with every UD achromat of highermagnification than 16x.Used without hemisphere, the UD acnromatsoffer a particularly long working distance.Due to their overall length of 33 mmthey must be attached to the microscope bymeans of the adapter ring 462991.w ryw

56Table 14UD Adrromatsfor universal rotary stage, without specimenprotection, parfocalized for 33 mmDesignationTechnical data for using the objectives with and without hemispherelnitial Focal Working Refractivemagni- length distance Catalog No. indexfication N.A. mm mm of objective rr" RadiusCatalog No.of hemisphereAchromat UD, 3.7 0.07 30.4 19.0 4620426.3x,0.12 N.A. 1.517 5.52 47 38240j2 41.8 13.5 1.517 5.52 4738256.1 0.13 44.6 13.51.648 5.52 4738261.517 12.56 473827012 25.5 6.5 1.517 12.56 4738286.1 0.13 24.81.648 12.56 473829Achromat UD, 9.6 0.11 15.6 13.5 46204416x.0.17 N.A. 1.517 47382414.9 o.17 11.2 101.557 5.52 47382515.8 0.18 10.7 101.648 5.52 4738261.517 12.56 47382714.9 0.17 10.51.517 12.56 47382815.8 0.18 10.01.648 12.56 473829Achromat UD, 12.7 0.38 12.6 46204520x,0.57 N.A. C** 1.517 47382419.7 0.57 1.517 47382521.0 0.611.648 5.52 473826Achromat UD. 25.8 0.41 6.9 46204640x,0.65 N.A. C** 1.517 5.52 47382440.2 0.641.51.517 5.52 47382542.7 0.68 3.7 1.5 1.648473826t Maximum permissible deviaiion 0.002'.Suitable for conoscopic observation.

57The 1x Planachromat is the objective with the lowest initial magnificationand built-in field lens. lt is not oarfocalizedwith the other objectives. Forpolarized-light microscopy we select themost strain-free obiectives.The 1.6x-5x Planachromat is particularly suitable for measuring purposes,because the magnification of theaerial image can be accurately adapted tothe graduation of the micrometer disk. Theobjective is used with a condenser whosefront lens is swung out of the light path. Refocusingis required if the magnification ofthe objective is changed.Special-purpose objectivesfor the normal transmitted-light microscope Table 15DesignationThe 32x Planachromat is an objective specially designed for ourRevolver Microprojector. lts front-lens mountis finished in black to avoid stray light. lfnecessary, it may be used on any other microscope.ln itialmagnrficationFocallengthmmWorking Cover-glassdistance thickness Catalogmm mm No.Planachromat,1x. 0.04 N.A. 1.08x 0.04 134.7 4.4 462010lx,0.04 N.A., POL 1.08x 0.04 134.7 4.4 4620111.6x-5x, 0.03-0.1 N.A. 1 .6x- 5x 0.03 - 0.1 41.2-20.8 32-1.5 46201332x,0.65 N.A.32.2x 0.65 5.6 0.3 0.17 46201663x, 0.90 N.A., oD(for uncovered specimens) 63.0x 0.90 3.0 0.09 460860

5BULTRAFLUARS These are special-purpose objectivesequally suited for observation by ultravioletand visible light. They are achromatic for arange from 230 to 700 mpz. Thus there is practicallyno shift in focus when changing fromone wavelength to another. The objectivesare corrected for 0.35 mm thick quartz(Homosil) cover glasses and designed forglycerin immersion, except the ULTRAFLUAR,10x. 0.20 N.A.. 462059.These objectives are very sensitive tofluctuations of temperature.Table 16DesignationFor wavelength 280 mplnitialFocalmagni-Iengtlfication N.A. mmWorkingd istancemmCovergrassth i cknessFor wavelength 546 mtlnitialmagnificationN.A.FocallengthmmCatalogNo.ULTRAFLUAR,10x,0.20 N.A. 10.0x 0.20 16.4 7 .4 9.4 0.19 17.5 46205832x,0.40 N.A., glyc. 32.0x 0.40 6.0 0.45 0.35 30.0 0.38 6.4 462060100x,0.85N.A.,91yc. 103.5x 0.85 1.79 0.12 0.35 98.0 0.81 1.93 462063100x, 1 .25 N.A., glyc. 100.9x 1 .25 1 .77 0.07 0.35 87.8 1 .15 2.00 46206432x,0.40 N.A., glyc., Ph 32.0x 0.40 6.0 0.35 30.0 0.38 6.4 462070100x, 0.85 N.A., glyc., Ph 103.5x 0.85 1 .79 0.12 0.35 98.0 0.80 1 .93 46207310x,0.20 N.A., POL 10.0x O.2O 16.4 7.4 9.4 0.19 17.5 46205932x,0.40 N.A., glyc., POL 32.0x 0.40 6.0 0.46 0.35 30.0 0.38 6.4 462061100x,1.25N.A., glyc., POL 100.9x 1.25 1.77 0.07 0.35 87.8 1.15 2.00 462065For achromatic-aplanatic ULTRAFLUAR-condenser 465557, see page 93.

59Jamin-Lebedeff transmitted-light Three objectives of the Achromat pOL Intinterference-equipment type and a specially selected condenserconvert any of our large polarizing microscopesinto an interference microscope. Thisallows the refractive index, thickness and drymass of discrete objects (i. e. objectswhich do not cover a continuous area) to bedetermined. The beam splitter in the condenserseparates the rneasuring and comparisonbeams. The beam combiner in theobjective causes the two beams to interfere.For further details see booklet 41-560.I nterference attachments Table 17withi nterference Achromatattachment POL lnlWorking dislancemmDistance betweenmeasuring andcomparison beamsmmCatalog No.forSTANDARDmicroscopesCatalog No.for UNIVERSAL,PHOTOMICROSCOPE,ULTRAPHOT10x, 0.22 N.A. 2.26 0.5 474403 474413ll 40x, 0.65 N.A. 0.2 0.17 474406 474416ill 100x, 1.0 N.A., oil 0.08 0.05 474408 474418

Objectivesfor reflected-light microscopy 60All our microscopes for opaque work arecomputed for uncovered specimens. Inview of the height of the vertical illuminatorto be inserted between the tube and the objectivethey have a relatively short parfocaldistance of 33 mm. Their initialmagnificationspartly deviate from our usual standard valuesin view of the standard magnifications of 50x,100x, 200x, 500x and 1000x used in metal-Iurgical work.With few exceptions, all our reflectedlightobjectives are designed as flat{ield objectives.In the systems supplied since 1965special care has been taken to eliminate reflectionsat glass-to-air surfaces by suitableshaping and coating of the lenses. This hasbeen surprisingly successful in the new seriesof EPIPLAN objectives.

61EPIPLAN HD objectivesfor bright{ield and dark-field observationby incident lightFor dark-field observation the objectiveproper is built into a concentric mirror or lenssystem. This reduces the free working distanceof the three low-power systems. Theseobjectives do not have the Whitworth thread0.8"xl/se" but the M24x0.75 screw thread.Table 18Desig nationInitial Focal Workingmagni- length distancefication N.A. mm mmCover- Catalog No.glass Objectivethickness formm nosepreceCatalog No.Objective withchange ring(46 62 55)EPIPLAN 4x, 0.10 N.A., HD 4.07x 0.1 36.3 460269 480269EPIPLAN 8x, 0.20 N.A., HD 7.96x 0.2 18.7 460369 480369EPIPLAN 16x, 0.35 N.A., HD 16.06x 0.35 10.4 460569 480569EPIPLAN 40x,0.85 N.A., HD 40.56x 0.85 4.6 0.23 460769 480769EPIPLAN 8Ox, 0.95 N.A., HD 80.7x 0.95 2.25 0.09 460869 480869EPIPLAN 100x, 1.25 N.A., oit, HD 100.6x 1.25 1.66 0.25 461969481969

62EPIPLAN objectivesfor bright-field observation by incident lightTo permit rapid change between thestandard magnifications used in metallography,these objectives are mounted on thetype lll D vertical illuminator 466247. On theUNIVERSAL microscope, the PHOTOMICRO-SCOPE and the ULTRAPHOT camera microscopemagnifications of 50x, 100x, 200x, 500xand 1000x can be achieved with Kpl 10x eyeoieces.Table 19Designationlnitialmagnif icationN.AFocal IengthmmWorkingd i stancemmEPIPLAN, 4x,0.1 N.A. 4.07x 0.1 36.3 9.0EPIPLAN, 8x, 0.2 N.A. 7.96x 0.2 18.8 7.2EPIPLAN, 16x,0.35 N.A. 16.06x 0.35 10.4 2.8EPIPLAN, 40x,0.85 N.A. 40.56x 0.85 4.6 0.23EPIPLAN, 80x, 0.95 N.A. 80.7x 0.95 2.25 0.09Cover-glassth i cknessmm

63LD-EPIPLAN objectives have an extra long working distance. Theyare required whenever the objective must beprotected against the effects of heat, causticvapors, etc., by means of a glass plate placedin the object field. LD-EPIPLAN objectiveswith the designation D : 1.5 mm are supliedwith a 1.5 mm thick protective cap. lf thespecimen is covered by a quarlz glass, e. 9.,as is usual in work with heating stages, thenthe quartz plate provides the necessary protectionin place of the protective cap.Due to their long working distance, theLD-EPIPLAN objectives are especially suitableas substage condensers. They are usedfor this purpose primarily in work with theM icroscope Photometer.Table 20Desi g nati onlnitialmag n i-ficatl o nWorking distance (mm) Cover-Focal with l.5mm with1.5mm glass Objectivelength cover- protective thickness Catalogmm glass cap mm No.Protectivecap, D 1.5LD-EPIPLAN, 4x,0.1 N.A. 4.06x 0.1 36.3 7.5 t.3 462101 462911LD-EPIPLAN, 8x,0.2 N.A. 7.94x 0.2 18.7 6.2 5.7 1.5 462102 462912LD-EPIPLAN,'16x,0.30N.A. 16x 0.30 10.1 4.1 3.6 t.c 462143 462913LD-EPIPLAN, 40x, 0.60 N.A. 40.1x 0.60 4.1 3.4 2.3 t.c 462104 462914LD-EPIPLAN, 40x, 0.60 N.A. 40.1x 0.60 4.1 3.1 462097LD-EPl PLAN, 40x, 0.60 N.A.,Pol* 40.1x 0.60 4.1 J.+ 2.3 462124 462916For the Nomarski interference-contrast method in reflected light use this objective, mounted almost strainJree, with protective capD 1.5 (462916) and interference-contrast attachment (474464\.No.

64EPIPLAN POL obiectivesfor polarized-light microscopy andthe Nomarski interference-contrast methodwith incident light (CNRS licence)centering change ringEPIPLAN POL objectivewith thread W 0.8"I nterference-contrastattach mentwith thread W 0.8"for EPIPLAN POL objectiveThe completely sirain-f ree bright-fieldobjectives are designed for polarized-lightwork, e. g. in ore microscopy or in connectionwith optically anisotropic metal phases. Theyare attached to the type llA, ll ST, Il C and ll Evertical illuminators by means of the changering 466256 in which they can be centered.As compared with dry objectives, immersionobjectives result in enhanced imagecontrast because reflections at the first surfaceof the front lens are made impossibleand the differences between the reflectivityand the intrinsic color of certain objectsstand out more clearly against oil thanagainst air.lf a vertical illuminator is to be used forthe Nomarski interference-contrast method,a special interference-contrast attachment isneeded for each EPIPLAN POL objective.Table 21DesignationN.A.FocallengthmmWorkingd istancemmlnitialmagnificationCatalog No.Cover-InterglassferencethicknessCatalog No. contrastmm obiective attachment"EPIPLAN, 4x,0.10 N.A., POL 4.07x 0.1 36.3 9.05 462001 474492EPIPLAN, 8x,0.20 N.A., POL 7.96x 0.2 18.7 7.1 462002 474492EPlPLAN, 16x, 0.35 N.A., POL 16.06x 0.35 10.4 2.7 462003 474493EPIPLAN, 40x, 0.85 N.A., POL 40.56x 0.85 4.6 0.23 462004 474494EPIPLAN, 80x, 0.95 N.A., POL 80.7x 0.95 2.3 0.09 462080 474495EPIPLAN, 4x,0.10 N.A., POL, oil 4.07x 0.1 36.3 0.3 462006EPIPLAN, 8x,0.20 N.A., POL, oil 7.96x 0.2 18.7 0.3 462007Epi-Achromat, 16x,0.40 N.A., POL, oil 16.0x 0.40 10.0 0.85 462008Epi-Achromat,40x,0.85 N.A., POL, oil 40.0x 0.85 4.6 0.5 462009EPIPLAN, 100x, 1.25 N.A., POL, oil 98.8x 1.25 1.94 0.28 462005 474496To be used on Type ll vertical illuminators with change ring 466258. On vertical illuminators with revolving nosepiece (Types lA,fllA, lllC) theinterference-contrastattachments4T4493/94/ andcorrespondingob.iectivesareparfocalized. Adapterring462996serves as connection

65EPIPLAN StM objectivesThese are designed forthe STANDARD UMinverted metallurgical microscope. Sincethey fit into the revolving nosepiece of thestandard transmiited-light microscopes andare parfocalized with the transmitted-lightobjectives, they may also be used for examininguncovered transparent specimens inall cases where ordinary transmitted-light objectiveswould give unsatisfactory results dueto the lack of a cover glass.EPIPLAN StM Ph objectives can be usedfor phase work if the diaphragm insert 467059is placed in the base of the inverted metallurgicalmicroscope. Every EPIPLAN StM Phobjective is supplied with an annular diaphragmwhich can be centered in this insert.Table 22Desj g nati onlnitialmagnrficationN.A.FocalI engthmmWorkingd istancemmCover-g lassth i cknessmmCatalog NoEPIPLAN StM, 4x. 0.10 N.A. 4.07x 0.10 36.3 9.0 462031EPIPLAN StM, 8x, 0.20 N.A. 7.96x 0.20 18.8 7.2 462032EPIPLAN StM, 16x, 0.35 N.A. 16.06x 0.35 10.4 2.8 462033EPIPLAN StM. 40x. 0.85 N.A. 40.56x 0.85 4.6 462034EPIPLAN StM, 80x, 0.95 N.A. 80.7x 0.95 2.25 0.09 462035EPIPLAN StM, 100x, 1.25 N.A., oil 100.7x 1.25 1.7 0.25 462036EPIPLAN StM, 16x, 0.35 N.A., Ph 16.06x 0.35 10.4 2.8 462037EPIPLAN StM, 40x, 0.85 N.A., Ph 40.56x 0.85 4.6 0.23 462038EPIPLAN StM, 100x, 1.25 N.A., oit, ph 100.7x 1.25 1.7 0.25462039

66EPIPLAN Ph objectivesfor phase-contrast workutith vertical il luminatorsEPIPLAN Ph objectivesTable 23DesignationThese objectives contain annular phaseplates specially adapted to the requirementsof incident-l i g ht phase-contrast m icroscopy.They are used in conjunction with a phasecontrastdiaphragm insert which among otherthings holds three suitable annular diaphragmson a change disk.EPIPLAN Ph objectives have the sameW 0.8" xl /ze" screw thread as the transmittedlightobjectives. They are not suitable forcombination with our phase-contrast condensersfor transmitted light.In itia ImagnificationN.A.FocalI engthmmWorkingd i stancemmCover-g I assth i cknessmmCatalog NoEPIPLAN, 16x, 0.35 N.A., Ph 16.04x 0.35 10.4 2.8 462027EPIPLAN, 40x, 0.85 N.A., Ph 40.56x 0.85 4.6 0.23 462028EPIPLAN. 100x. 1.25 N.A.. oil. Ph 100.7x 1.25 1.62 0.25 462029Phase-contrast diaphragm inserl 472073 for vertical illuminator type ll G with single objective changer,Phase-contrast diaphragm i^sert 472072 for vertical illuminator iype lll C with a revolving nosepiececan be combined with the UNIVERSAL and ULTRAPHOT microscopes

Antiflex immersion objectives67ln the case of reflected-light bright{ieldillumination, part of the illuminating tight isalways refiected back to the image planefrom the glass-air surfaces of the objectivebefore it has fully passed through the latter.The amount of light that is reflected dependson the type of objective and the adjustmentof the light path. lt may even happen that animage of the objective aperture becomesvisible. This effect is particularly disturbingwhen viewing objects of low reflectivity. ltcan be eliminated by using polarized light forillumination, whose state of polarization ishardly changed by specular reflection. Whenan analyzer in the iight path is oriented sothat its plane of vibration is perpendicular tothat of the light reflected from the lens surfaces,this light can be extinguished. Thelight diffusely reflected from the specimensurface, however, will pass through the analyzerpractically unattenuated because it isdepolarized in the course of diffuse reflection.In the case of specular reflectors-whichmost polished specimens are-this method ispossible only if a suitably oriented, circularlypolarizing f ilter is inserted between the specimenand the objective. Some of our brightfieldreflected-light objectives are providedwith such filters. They are then called "Antiflexobjectives". These are available in theforrn of EPIPLAN and achromatic objectivesfor incident-light work with oil and methyleneiodide.Antiflex immersion objectives give particularhigh contrasi for bright-field incidentlightobservations, because the use of animmersion medium eliminates all reflectionsat the first surface of the front lens, while theAntiflex system eliminates all reflection fromthe surfaces of all other lens elements, andbecause the differences of reflectlvity andintrinsic color of certain objects are morepronounced and more clearly visible in oil

6Bthan in air. These objectives are especiallysuitable for objects of low to medium reflectivity(coal petrography) and specimens ofvarying reflectivity (weak to strongly absorbingor refracting). Methylene iodide immersionobjectives generally produce the sameresult as the corresponding objectives for oilimmersion, but are even better suited for objectsof extremely low reflectivity (coal petrography).The circularly polarizing filter located infront of their lens elements makes these objectivesunsuitable for certain measuringtechniques, e. g. for the polarized-light analysisof the vibrational state of polarized reflectedlight.Antif lex immersion objectivesTable 24Desi g nati onlnitialmagnrficationN.A.FocallengthmmCover- Catalog No. Catalog No.Working glass Objective Objectivedistance thickness for withmm mm nosepiece change ringEPIPLAN-Antiflex,8x,0.2 N.A., oil 7.9x 0.2 18.750.4 461364 481364Antif lex-Ep i-Ach ro m at,16x, 0.40 N.A., oil 16.0x 0.4 10.0 0.45 461554 481554Antif lex-Ep i-Ach rom at,40x.0.65 N.A.. oil 40.0x 0.65 4.6 0.5 461754 481754EPIPLAN-Antif lex,2.5x, 0.08 N.A., methylene iodide 2.9x 0.08 54.8 0.3 461163 481163EPIPLAN-Antiflex,4x, 0.1 N.A., methylene iodide 4.1x 0.1 36.3 0.4 461263EPIPLAN-Antif lex,8x,0.2 N.A., methylene iodide 7.9x 0.2 18.75 0.4 461363 481363A ntif lex-Ep i-Ach romat,16x, 0.40 N.A., methylene iodide 16.2x 0.4 10.0 0.35 461553 481553Antif lex-Epi-Ach romat,40x, 0.65 N.A., methylene iodide 39.6x 0.65 4.6 0.25 461753 481753

Photomicrographicobjectives69LUMINARS with iris diaphragmfor photography by transmitted or incidentlight, with dark-field illumination produced bystereomicroscooe ill uminators.Table 25DesignationDistance betweenfocal plane andFor infinite front lens vertexFocal object distance (mm)lengthRelative object- imagemm N.A. aperture side sideMagnifications obtainablewithULTRAPHOT"16 mm LUMINAR 16.1 0.2 1:2.5 10.'1 11.5 50x-70x40x-55x25 mm LUMINAR 26.0 0.14 1 :3.5 21.9 230 31x-43x25x-34x40 mm LUMINAR 39.9 0.11 1:4.5 34.9 27.9 20x-27x16x-22x63 mm LUMINAR 63.4 0.11 1:4.5 54.8 45.0 11 .5x-16x9.5x-12.5xwithUNIVERSALm rcroscope,PHOTO-MICROSCOPE Catalog No14x-22x 4625118x-14x 4625134x-Bx 4625152x-4x 462517100 mm LUMINAR 102.3 0.08 1:6.3 76.2 91.8 462519100 mm LUMINAR 102.3 0.08 1 :6.3 76.2 91.8 6.5x-9.5x 1.5x-28x 462529for Luminar head5.3x-7.5x2.5x to 5x LUMINAR vari- 0.04/2.5x-3.6x462531for ULTRAPHOT able 0.053.6x-5x* A continuous series of magnifications can be achieved with the ULTRAPHOT if the O.8x auxiliary system, Catalog No.462580, ieemployed. The magnifications corresponding to this combination appear in small print.

70100 mm LUMINAR The 100 mm LUMINAR, Cat. No. 462519,has an M 44x0.75 screw thread at either end.Thus, when the protective ring in front hasbeen removed, the objective may also beused in an inverted position to secure reducedscales.100 mm LUMINAR The 100 mm LUMINAR, Cat. No. 462529,is basically the same objeciive as No. 462519,With its special mount it can be attached tothe Luminar head of the ULTRAPHOT.to 5x LUMINARThe 2.5x to 5x LUMTNAR is a speciatpurposeobjective designed for very smallscales. lt is exclusively intended for theULTRAPHOT camera microscope and canonly be used for transmitted lighi in conjunctionwith the macro-stage 472561. Whenordering the macro-stage, please indicate theserial number of vour ULTRAPHOT.

71Epi-LUMINARS These are intended for photography withwithout iris diaphragm with field tens our ULTRAPHOT camera microscope usingreflected-light bright-field illumination. Theobjectives 462542/43/45 can also be usedon our UNIVERSAL microscope.Table 26DesignationFocallengthmmCatalog Notorobjectivel\4ag n if icationsto be achieved withULTRAPHOT20 mm Epi-LUMINAR 18.7 462542 44.5:1-61 :135:1-49:125 mm Epi-LUMINAR 25.0 462543 33:1-46:127:'l-36:140 mm Epi-LUMINAR 40.0 462545 22:1-29:117 :1-23:163 mm Epi-LUMINAR 63.4 462517 12:1-17.5:1'10:1-14:1'100mm Eoi-LUMINAR 102.3 462529 8.5:'1 - 12:16.5:1-9:1Catalog No.for macroilluminator47 257547 257547 257547 257647 2577The magnifications in small print can be achieved by using the O.8x auxiliary system (462s80) with the Epi-LUMINARS

ZEISS eyepieces 72For tubes with an inside diameter of23.2 mm; adapted to a location of the realintermediate image 10 mm below the tubeedge; with compensating effect adapted tothe correction of our objectives.C-type eyepieces may be used in conjunctionwith simple types of objective. Objectivesof higher correction should, if possible,always be combined with Kpl eyepieces.This applies above all to the Planachromatsand Planapochromats.Table 27Desi g nationre I iefmmFocalIengthmmEyepiecemagnrficationFieldof-viewnumberAng leof viewCatalogNo.5x compensating eyepiece 5x 50.5 20 23" 4637106.3x compensating eyepiece 6.3x 39.9 18 26" 4638108x compensating eyepiece 8x 31.2 16 300 46391010x compensating eyepiece 10x 24.9 16 360 46401012.5x compensating eyepiece 12.5x 20.0 12.5 360 4641108x Kpl eyepiece 8x 31.5 18 33 46392010x Kpl eyepiece 10x 25.0 16 360 46402016x Kpl eyepiece 16x 11 15.6 10 36" 46 422020x Kpl eyepiece 20x 8.5 12.5 360 46 432025x Kpl eyepiece 25x 6.5 10.0 6.3 360 46 442016x Kpl wide-angle eyepiece 16x 12 15.6 16 55" 464244

73Eyepieces for spectacle wearersThese have a particularly long eye reliefand are therefore suitable for wearers of eyeglasses.lt should be noted, however, that thespectacle lens also has an influence on theheight of the exit pupil. Minus lenses magnify,plus lenses reduce the image accordingto their power. A wearer of strong plus lensesmay therefore be unable even with these eyepiecesto approach the pupil of his eye closeenough to the eyepiece for it to coincide withthe exit pupil of the latter.Table 28Des ig natio nEyepiecemagnificationEyereliefmmFocalI engthmmFieldof-viewnumberAngleof viewCatalogNo.8x Br Kpl eyepiece 8x 17 31.3 18 32" 46392212.5x Br Kpl eyepiece 12.5x 16 19.8 12.5 360 46412010x Br Kpl wide-angle eyepiece 10x 20 25.1 18 41" 464042-12.5x Br Kpl wide-angle eyepiece 12.5x 15 20.3 18 50" 464142.Eyepiece is supplied with foldable rubber eyecup.

74Eyepieces for micrometer disksIn these eyepieces, the mount of the collectivelens is designed to hold micrometerdisks. The disk is pressed against the eyepiecediaphragm by means of a clip-on ringso that it rests in the image plane. The eyepiecemay also be used, with or without amicrometer disk, combined with an ordinaryeyepiece of the same specification (table 27)in a binocular body.Table 29Designationtrv6hi6^amagnificationtr\,Areliefm mFocallengthmmFieldof-viewnumberAngleof viewCatalogNo.8x compensating eyepiecefor 17 mm dia. micrometer disks 8x 31.2 16 300 46491312.5x compensating eyepiecetor 17 mm dia. micrometer disks 12.5x 20.0 12.5 360 4641138x Kpl eyepiecefor 17 mm dia. micrometer disks 8x 31.5 18 330 46392312.5x Br Kpl eyepiecefor 17 mm dia. micrometer disks 12.5x to 19.8 12.5 360 46412316x Kpl eyepiecefor 17 mm dia. micrometer disks 16x 11 15.6 10 360 46422320x Kpl eyepiecefor 17 mm dia. micrometer disks 2Ox 8.5 I z.c 360 46 432310x Br Kpl wide-angle eyepiecefor 19 mm dia. micrometer disks 10x 20 25.1 Itt 41" 464043.10x Br Kpl wide-angleyepiece for 19 mmdia. micrometer disks with orienting screw 10x 20 25.1 18 44" 464046Eyepiece is supplied with foldable rubber eyecup.

75Micrometer disksThe following micrometer disks with diameter17 or 19 mm to be used in the eyepieceslisted on table 29.The eyepieces for the stereomicroscopeslisted in table 32 require micrometer disks of22.5 mm diameter.0 - _- :1_--= :2:10 mm eyepiece micrometer, with 100 divisions,17 mm dia.Same as above, but with 19 mm dia.Same as above for stereomicroscopesCatalog No.47 40 1147 400247 40615 mm microrneter disk, with 100 divisions, 17 mm dia. 474010" t10 mm contrast micrometer disk, with 100 or 200 divisions,17 mm dia. 474012l -10 mm line contrast micrometer disk, with 100 divisions,17 mm dia. 474O1gThe shaded area transmits 5 to 10% of the incident light./#/ffi\/ Hj+:Fi+r]]1]]]+| \\|]:I]:I]:l]:1ffi/\--/\I]:]]]:r]:]]:llffi/Net micrometer disk 10x10 mm,2Ox20 squares,17 mm dia.Same as above, but with 19 mm dia.Same as above for stereomicroscopes47 401447 40 4447 4062

76Catalog No.Net micrometer disk 5x5 mm, 10x10 squares,17 mm dia. 474015Crosshair disk, 17 mm dia.Same as above for stereomicroscopes47 401647 406010 mm crosshair micrometer disk, with 100 divisions'19 mm dia. 474007r[-_l )\"/[--lt - lReticule for color television microscope,19 mm dia. 474009Reticulocyte disk 47 4032To simplify the counting of reticulocytes and thrombocytes*, thismicrometer disk contains a small square within a large square(8x8 mm, 11.2 mm diagonal). The areas of the two squares are ina ratio of 10:1. The number of reticulocytes in the large square isdetermined in relation to that of the erythrocytes in the smallsquare.This disk is preferably used in the eyepieces with focusing eyelens, Sx Kpl (463923) and 12.5x Br Kpl (464123).Object marker with diamond tiP 462960This is screwed into the microscope like an objective. Thediameter of the circle to be made around the object can be set ona graduation. Then the diamond tip is lowered onto the coverglass and the circle engraved by turning a ring.Brecher and Schneidermann, The American Journal of Clinical Pathology,20, 1079-1083 (1950)

77Catalog No.Stage micrometersA glass plate in a metal slide is providedwitha5mrnscaledivided into 5 intervals.A further distanceof 1 mm is divided into100/100 mm : 10p.[-1[n n=)0For transmitted light: positive stage micrometer5*100/100 mm, in case 474020For rellected light: stage micrometer asabove, but without cover glass 474022For ultraviolet microscopy: stage micrometerwith slide and cover glass made of quartzglass 474023For transmitted light: negative stage micrometer5*100/100 mm, in case 4740215 4 3 2 r 0,,',l,,,rlr,,rl,,r,lrlrl,rrl,r,r]rrrrlrrrrlrrrrl l l5I t t lFor stereomicroscopes: stage micrometer25+50/10 mm, in case47 4025Object finder 462965To allow the accurate relocation of object details, threesquares marked ABC, each containing 30x30 smaller squares,are engraved on a 26x76 mm slide. The 0.75x0.75 mm squaresare figured from 1 to 900 and further subdivided into 3x3 squares.The slide with the specimen need only be exchanged for the objectf inder to give an accurate reading of the position of the stage.

7BPointer eyepiecesThese eyepieces have a pointer in theimaEe plane, the tip of which can be movedto any point in the field by turning a knob androtating the eyepiece in the tube. For use inbinocular bodies, the pointer eyepiece shouldbe paired with an ordinary eyepiece of thesame optical daia, as listed inIable2T.Table 30Designationrel i efmmFocalI engthmmEyepiecemagnificationFieldof-viewAngle Catalognumber of view No.Bx compensating eyepiece with pointer 8x 31.2 16 300 46391812.5x Br Kpl eyepiece with pointer 12,5x 16 19.8 12.5 36" 464128

79POL crosshair eyepieceswith focusing eye lens andorienting screwThis eyepiece is inserted into the tubecorrectly oriented. The crosshairs have beencentered with high accuracy. They mark theoptical axis of the polarizing microscope andthe vibration direction of polarizer and analyzerin their zero positions. They serve as anindex for measuring azimuth angles by rotationof the stage.Crosshair micrometers are also suited forlength measurements under orthoscooic andconoscopic observation.Table 31DesignationEyereliefmmFocallengthmmEyepiecemagnilicationFieldof-viewn um DerAngleof viewCatalogNo.Bx Kpl crosshair eyepiece pOL12.5x Br Kpl wide-angle eyepiece8x 31.5 18 330 463925with crosshair micrometer 12.5x tc 20.3 18 50 464145

80Eyepieces for stereomicroscopes These are eyepieces specially designedfor use with our stereomicroscopes, for aninside tube diameter of 30 mm. They areadapted tor a real intermediate image located10 mm below the tube edge and have nocompensating effect.Table 32DesignationEyepiecemagnificationEyereliefmmFocallengthmmFieldof-viewnumberAngleof viewCatalogNo.4x eyepiece 4x 10 62.6 30 27 463601.10x eyepiece 10x 12 25 20 43" 46400'1Same for micrometer disks 46400425x eyepiece25x10cc- 46 4401Same for micrometer disks46 440410x Br wide-angle eyepiece 10x 18 25 25 5b- 46 4002"16x Br wide-angle eyepiece 16x 15 15.6 16 bb- 464202.) not for stereomicroscope lVThe 10x stereoscopic depth-measuringCatalog No. 464005, with integral index foreyeplece stereoscopic depth measurement is identicalin design to the 10x eyepiece for micrometerdisks.Clamping ring 464912 serves for orientationof the eyepiece.

Table 33Transfer factorsFocal length ofmicroprojection Camera Iens of focal lengtheyepiece 100 mm 125 mm 160 mm125 mm 0.8x 1x 1.25x'100mm 1x 1.25x 1.6x80 mm 1.25x 1.6x 2x63 mm 1.6x 2x 2.5x81Microprojection eyepieces For the recommended projection d istance,Eyepieces of long focal length for use the scale factor of all projection eyepieces,in microprojection equipment i. e. the relationship between their field-ofviewnumber and the diameter of the projectedimage, is identical. lt is 100.This means that all the eyepieces, whichhave a field-of-view number of 20, will producean image ol 2 m diameter at this distance.In exceptional cases, these eyepiecesmay also be used for visual observation ifeyepiece magnifications are required whichare lower than those of the normal eyepieces.This is why the values corresponding to eyepiecemagnification and eye relief are alsoindicated. The eyepieces may also be usedto advantage if in cinemicrography on 16 mmor 8 mm film the aerial image produced bythe camera lens is to be transferred to thefilm plane by the eyepiece with litile or nomagnification. In this case the camera. witha lens of suitable focal length, should bearranged above the eyepiece. The cameraIens may be a simple achromatic lens (telescopeobjective). Table 33 gives the transferfactors which can be achieved, for example,with telescope objectives and the four microprojectioneyepieces.For details on microprojection equipmentincluding projectives see brochure 41-480.Microprojection eyepiecesTable 34Desig natj onEyepiecemagnificationEyereliefmmRecom_mended forFocal Field- projectionIength of-view distance of Catalogmm number m No.125 mm microprojection eyepiece 2x 30 126.0 20 12.5 463379100 mm microprojection eyepiece 2.5x 30 100.0 20 10 46347980 mm microprojection eyepiece 3.2x 30 75.3 20 8 46357963 mm microprojection eyepiece 4x 30 63.1 20 6.3 463679

cial-urpos eepteces 82Screw micrometer eyepieceswith inner readingScrew micrometer eyepieces are used formeasuring object lengths. The microscopistmay now read the measured value off themicrometer, measurements with an accuracyeyepiece. Thus, inner reading of measuredvalues avoids mistakes caused by accommodation.After calibrating with the stagemicrometer, measurements with an accuracyof 1/rooo of a millimeter can be made.Table 35with Kpl 8xCatalog No.with Kpl 16xCatalog No.Screw micrometer eyepieces with inner readingfor standard monocular tube with 25 mm outside diameterand for polarizing tube 463973 464273for tubes with 33 mm diameter, for stereomicroscopes 463983 46 4283

B3Catalog NoK 8x goniometer eyepiecefor standard monocular tubewith 25 mm outside diameter 4639 74for tube with 33 mm diameter,for stereomicroscopes 46 3984for polarizing tube 4639 94This eyepiece is provided with crosshairs which can be rotatedthrough 360o about the intersection of the two hairs. The angleof rotation can be read off a graduation with vernier to within1/.roo. The eyepiece is intended for measuring angles in themicroscope field of view.K 8x and K 16x eyepieces for Microhardness Tester 469977with focusing eye lensThis is a special eyepiece for evaluating the Vickers indentationsproduced by means of a Microhardness Tester. lt containstwo micrometer disks with rectangular patterns of dashedlines which combine to form a crosshair in zero position. Thetwo disks can be symmetrically shifted in relation to the verticalcenter line by means of a knob. The diagonal of the indentationis measured by this shift. The eyepiece is of the interior readingtype.K 10x UV projective 46 4082This system is designed to produce a second real imagee. g. on a Iight-sensiiivemulsion (photomicrography) or in aphotometer system (Type 05 UV-microscope photometer).8x Kpl counting eyepiece 463971This eyepiece can be clamped in the monocular tube. lt corrtainstwo diaphragm blades with rectangular cutouts, whichcan be shifted symmetrically in relation to the vertical centerline, thus making it possible to select square sections from thefield of view. When using an object chamber of known depth,volumes can thus be easily limited for counting purposes. Inother words, the eyepiece is intended for counting particleswithin a certain volume.

B4Catalog No.8x Kpl eyepiece wilh adjustable counting lines 4639 70This has primarily been developed for counting plankton samples.However, it may also be used to advantage for evaluatingother samples. lt is clamped in a monocular tube and containsa fixed horizontal hair and two vertical hairs which can beshifted symmetrically in relation to the vertical center line bymeans of a knurled ring. The two adjustable hairs serve todelimit counting areas of any desired size.10x Br K eyepiece for spectacle wearers,for micrometer-disk turretfor standard monocular tubewith 25 mm outside diameter 464075for polarizing tube 4640 95This eyepiece accepts revolving disks which serve for the convenientdisposition and rapid exchange of several micrometerdisks in the intermediate image plane. This may be of advantagefor evaluating clusters of particles in connection withstandard series, for measuring particle size and determiningvolume.Each turret contains either one revolving disk or two, arrangedone above the other, with 6 or'12 reticules, respectively. Inanother position, the light passes freely through the disks.Type'a' "honeycomb net" micrometer-disk lurret 47 4120The micrometer disks built into this double turret conform toASTM E 19-46. The 11 disks correspond to the ASTM numbers0 to 10. With the aid of the appropriaie objectives, theASTM numbers 2to lZ can thus be covered. The honeycombnets are extremely convenient for estimating particle sizeswith relative radii of l/21 and 2:1. One opening contains amicrometer disk with 10 mm/100 mm and 4 inch/128 graduations.

B5Catalog No.Type'b' "austenite-ferrite" micrometer-disk turret 474121Each of the two revolving disks holds six micrometer diskswith austenite-ferrite grain sizes in a ratio of 1:1 conformingto the Steel and lron Standard 1510-6'1. The disks bear thedata for the Steel and lron Test Nos. 2 to 7. In conjunctionwith our EPIPLAN objectives it is thus possible to cover thenumbers 0 to g.The micrometer-disk turrets 474121 and 474122 together givethe overall requirements of the Steel and lron Standard 1510-61and should therefore be ordered and treated as one unit.Type 'c' micrometer-disk turret, 474122"ferrite grain sizes 2:1 and 4:1"This double turret is identical in design to the turret 474121,with the only difference that it covers the grain size ratios 2:1and 4:1.This micrometer-disk turret reflects all the different conditionsof the Steel and lron Standard 1510-61 in conjunction with theturreI4T 4121. The two should therefore be ordered and treatedas one unit.Type 'd' micrometer-disk turret,474123"ASTM-E112 untwinned grainsn,On this turret the grain-size samples are arranged accordingto ASTM-E 112 with the whole numbers 0-4 or, respectively,7 and 8 as well as the half numbers 4.5-5.5. Variation of theinitial magnifications of the objectives thus allows the ASTMnumbers 2 to 10 to be covered. The distribution of grain sizeshas been particularly adapted for the assessment of austenitegrain sizes, but it may also be used in conjunction with isometricgrain-size systems.

B6Catalog No.6.-*'*'i?}:o'"o}1 2 3 1 5 6 7 8 9 1 0Integrating micrometer-disk turret 4741 30This turret takes the place of the well-proved integrating eyepieceL With this turret, sets of points arranged in a squareare superimposed on the aerial microscopic image accordingto the principle of point analysis. Any overlapping of a pointwith a component is counted as a hit. The ratio of the numberof hits to the total number of points gives the partial volumeorthe percentage by volume.The revolving disk has seven openings. For optimum geometricadaptation to the object, integrating disks are mounted in fourof these openings. The disks have the same base length and25, 100,400 and 900 points, respectively. In addition, the largeclusters of points are centrally subdivided into 25, 100 and400 points so that small object fields can be uniformly countedwith these partial nets. lf the coordinate motions of the attachablemechanical stages are made parallel to the sides of thecounting nets, then the specimens can be completely coveredwith the point nets.Disks 5 and 6 of the turret are intended for the determinationof grain sizes, shape factors, specific surfaces, diameters ofmedium-sized particles according to the diameter method, anddetermination of medium-sized areas according to the circlemethod. With the disk 5, the radius quotients of successivecircles behave, according to international practice, as 1/2:1,i. e. the quotients of the second following radii are in the ratio2:1. The radii of the grain-size disk 6 are selected in linear,decimal order in steps of ten. ln addition, the radii of the Aterbergdivision customary in sedimeniary petrography, 2-63-20-63, have been included. The seventh disk, finally, is providedwith crosshairs for quantitative microscopy.K 8x double eyepiece with pointerCatalog Nofor standard monocular tubewith 25 mm outside diameter 4649 20for tube with 33 mm diameter,for stereomicroscopes 4649 21for polarizing tube 4649 22This unit has two separate eyepieces spaced approx. 380 mm.

87Bestell-Nr.Centering telescope 46 4820This is a small telescope inserted into the tube instead of theeyepiece and serving for observation of the magnified exitpupil of the microscope objective as well as the aperture stopimage appearing in it. This allows accurate checking of theobjective aperture. lt serves instead of a Bertrand lens to adjustthe phase-contrast annular diaphragm of the condenser inrelation to the phase annulus in the objective, or to observeinterference figures.The centering telescope is focused by shifting its eyepiece.Centering telescopewith built-in 5:100 micrometer diske. g. for the measurement of interference angles.46 4821Klein magnifier464830Clip-on eyepiece magnifier designed to magnify the exit pupilof the entire microscope. lt serves the same purpose as thecentering telescope.Pupillary spectroscope 474300This low-power eyepiece with focusing eye lens and an irisdiaphragm for limiting the field of view is combined with a handspectroscope. The slit of the spectroscope is located in theplane of the eyepiece exit pupil. With the aid of the iris diaphragmthe detail to be investigated spectroscopically can besingled out and its characteristic absorption or emission spectrumviewed in the spectroscope. The hand spectroscope permitsa wavelength scale and, if desired, a comparison spectrum,to be projected into the image. With the aid of a specialpurposecamera the spectra can be photographically recorded.

88Intermediate The total magnification power of a microscope,calculated from the initial magni-magnif ication-changing systemsfication of the objective and of the eyepiece,can be varied by means of an optical lenssystem.Table 36Designation Factor for microscope Catalog No.Wide-field system 0.8x To be screwed into the body 473067tube, used primarily withthe STANDARD K and RWide-field changer 0.8x - 1x STANDARD K and R, 473068with holder screw in limb tooMagnification changer 1.6x-1x Same as for the wide{ield 473060changerMagnification changer 2x-1x Same as for the wide-field 473065changerOPTOVAR 1x-1.25x-1.6x-2x STANDARD R, WL,473050among othersWidejield OPTOVAR 0.8x - 1x - 1.25x - 1.6x STANDARD R, WL,473070among othersOPTOVAR on tube head 1.25x- 1.6x-2x UNIVERSAL 4716 45"PHOTOMICROSCOPE. part or stand 47 21 89"OPTOVAR on tube head 1.25x-1.6x-2x ULTRAPHOT 472645-. Wide-field OPTOVAR 0.8x-1x-1.25x PHOTOMICROSCOPE. UN IVERSALon tube head is obtainedULTRAPHOTif the standard revolvingnosepiece is replaced bythe nosepiece with widefieldsystem (473155).

CondensersB9Z-type condensersFor the condenser carrier of our routineand research microscopes, parfocalized fora distance of 38.2 mm, with built-in apertureiris diaphragm for bright field.Simple condensersTable 37Designation Front lens N.A.F^^rllengthmmnhi6^+distance*mmCatalogNo.Condenser. 0.6 N.A..SZ fixed 0.6 24.8 46 5200Condenser, 0.9 N.A., Zwith swing-out lensswinging out 0.9 13.1 2.0 -2.2 465252Condenser. 1.3 N.A.. Zwith swing-out lensswinging out 1.3 8.4 1.6 - 1.8 465253Condenser, 0.9 N.A., Z. POL swinging out 0.9 13.1 2.0 -22 465262Condenser, 1.3 N.A., Z,POLwith swing-out lensswinging out 1.3 8.4 1.6 - 1.8 465263Phase-contrast condenser ll Zwith swing-out lensswinging out 0.9 13.1 2.0 -22 465270Phase-contrast condenser llZ, POLwith swing-out lens swinging out 0.9 13.1 2.0 -22 465282. The object distance indicates the position of the image of an infinitely distant lamp field stop above the stage surface inglass tor a medium aperture and a condenseracked up to its upper stop. This measure is an indication of the thickness of theobjects which can still be properly illuminated with the condenser following Kohler's method.

90N.A. 1.4 achromatic-aplanaticondenser ZUniversal variable-focus condenser forbright-field illumination, if used together withthe two auxiliary front lenses of N.A. 0.6 andN.A.0.9.ffi@Table 38Front lensN.A.Focal lengthmmObjectdistancemmCatalogNo.lmmersed 1.4 6.8 1.3-1.5 465257Without front lens 0.32 30_7 37Auxiliary front lens0.63 0.64 15.3 6.6 4652550.9 0.9 10.4 1.8 465256AcJr ro m ati c-ap I a nati cphase-contrast condenser lY Zl7Dry condenser of long objective distanceswiih aperiure iris diaphragm for bright fieldand three annular diaphragms on a revolvingdisk, matched with our phase-contrast objectives,for phase-contrast observations of livingobjects in sample chambers.Table 39N.A.Focal lengthmmObject distance in glassmmCatalogNo-0.63 15.3 11 465272

91Acfiromatic-aplanatic bright-field dark-fieldphase-contrast condenser VZ 465277&@For bri g ht-f ield this is a variable condenserlike the N.A. 1.4 condenser Z, 465257.For the phase-contrast technique itmay be used with the N.A. 1.4 front lens inconjunction with our Ph objectives of 16x orhigher power.For dark-f ield work, the N.A. 1.4 frontlens of the condenser is immersed (objectdistance in glass 1.1-1.3 mm). lts aperture isthen 1 .1-1.4, and it is suited for use in conjunctionwith N.A. 0.65 to 1.0 objectives. Highpoweroil immersion objectives must beequipped with an iris diaphragm.Achromatic-aplanatic phase-contrastffuorescence condenser 465278@@This is the same condenser as 465277.However, in positions 2 and 3 of the revolvingdisk, which are marked in blue, it containstwo additional annular diaphragms forpolarized light. In conjunction with the lightregulator 477220 these permit a phasecontrastimage to be continuously convertedinto a fluorescent image.Achromatic-aplanatic phase-contrast andinterference-contrast condenser 465294For phase-contrast illumination this condenserwith strain-free mounted lenses issimilar to the condenser lV Z, 465277. In thepositions l, ll, lll and lV the revolving diskcontains a double-prism quartz wedge andan aperture diaphragm. Used together withPlanachromats 6.3x, 16x, 40x and 100x, apolarizer and an interference-contrast slide474431 or 474433, this condenser will giveNOMARSKI d ifferential interference contrast.A rotary specimen stage will be found helpfulfor this type of work (booklet 41-210).

92Pancraticcondensor, 0.13. .0.90 N.A. 465290Condenser head, 1.3 N.A. 465291The pancratic condenser is based on theidea that an additional optical system ofcontinuously variable focal length should belocated between the condenser system andthe condenser diaphragm to image the diaphragmin the focal plane of the condensersystem at a continuously variable scale andthus to cause a continuous change of aperture.Since such a system at the same timemakes it possible to image the aperture of thelamp condenser in the specimen plane in thesense opposed to that of the change in imagescale, the product of the field-of-view diameterand the aperture remains constant. lf allelements are suitably matched, the basic requirementof the Kohler illumination methodcan be satisfied in a very neat manner witha minimum of manipulation.Operation is limited to adjusting the condenserfor the maximum aperture of the objectiveused simply by turning a knob. Forfurther simplification, three stops are providedfor low-power, medium-power andhigh-power objectives. Reduction of the illuminatingaperture to a value below that ofthe maximum aperture of the objective usedfor observation is achieved as usual by varyingthe aperture diaphragm located in a specialinsert in the microscope base. lt ismounted so that it can be shifted laterallyand rotated and thus also allows oblique illuminationof any desired azimuth.The pancratic condenser can be used asdry condenser for apertures up to 0.9 or asimmersion condenser up to a maximumaperture of 1.3. lt serves to illuminate thefields and apertures of all objectives from2.5x to 100x.The pancratic condenser can easily beused for phase contrast. For this purpose, anannular diaphragm supplied with the unit isinserted at the plane of the aperture diaphragm.By varying the adjustment of the

93pancratic system, the image of the annulardiaphragm in the focal plane of the phasecontrastobjective can be perfecily matchedto the size of the phase annulus there andcentered with the aid of the diaphragm adjustment.N.A.0.6 conoscopic condenser UD465550 This condenser is specially adapted tothe position of the object on the universalstage and serves for optimum illumination ofthe conoscopic interference pattern. In conjunctionwith hemispheres with a refractiveindex of 1.555 it acts with an aperture of 0.6.In air its object distance is 17 mm. lts workingdistance from 1 mm thick specimen slidesis then 15 mm.N.A. 0.8 achromatic U LTRAFLUAR-condenserwith iris diaphragm 46SS57This condenser for work by ultravioletlight is corrected and parfocalized like anULTRAFLUAR objective (see page 58). At awavelength of 280 mp its focal length is6.2 mm and its initial magnification 29.5x.Although it is a dry condenser, it may also beimmersed in the usual glycerin used in UVmicroscopy.This condenser is inserted into the condensercarrier of our microscopes in conjunctionwith change ring 466258, intermediatering 462990 and carrier Ztor microscopeobjectives, 465545.

94Dark-field condensers Table 40DesignationN,A,FocallengthmmObjectdistancemmForobjectivesof N.A-CatalogNo.Ultracondenser, 1 .2...1.4 N.A., oil 1 .2-1.4 5.9 1 .1-1.3 0.75 - 1 .0 465500Dry dark-field condenser, 0.8. ..0.95 N.A. 0.8-0.95 8.2 6 0.6 -0.75 465505Dry dark{ield condenser,0.7 ... 0.85 N.A. 0.7-0.85 8.5 6.5 0.4 - 0.6 465506For our microscopes with centering carrier, each of these condensers must be equipped witha condenser holder Z,465542.For insertion into a condenser sleeve,the ultracondenser must be equipped with the centerable condenser holder Sthe other condensers with the condenser holder S4655 41,46 55 40.

95Spectacle-lenscondensers For photomacrography with LUMINARS(table 25), for photography by polarized lightas POL models.Table 41Spectacle-Diameter of clip-onlens Focal length diaphragmFor LUMINAR condenser mm rmmlCatalog No.POL modelCatalog No.16 mm 1* 21 3.5 465561 46557125 mm 2* 3 6 6 465562 46557240 mm 3* 4 7 9 465563 46557363 or 100 mm 4 82 15 465564 465574100 mm 137 27 465565 465575* For insertion into the centering carrier of our microscopes each oi these condensers must be equipped withcondenser holder Z, 4655 42.

PHOTOMICROSCOPE llwith integral, fully automatic 35 mm camera including photomultiplier;equipped for differential interference-contrast in transmitted light, phase contrast and brighl field965.

ULTRAPHOT lll Camera Microscope tor 4"x5" or35 mm photographywith fully automatic, integral cameraincluding photomultiplier. This instrument can be used tcir att i6ctinifiuei appiieo-in microscopy.97