Calibration of a Terrestrial Laser Scanner - Institute of Geodesy and ...

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—96 5. Kinematic Laser ScanningTable 5 3 shows two aspectsFirst, the precision of the radius o> does not influence the precision of thecenter angle aaSecond, both anincreasing radius and an increase in the precision in the base ab lead toanincreasing precision of the center angle aaFurthermore, at least a value for ab « 0 5 mm as well as adistance of 2 m to 5 m are required to meet the criterion of a time precision for
5.2 Rotation Time of Rotating Mirror of Laser Scanner 97Table 5.5 shows the influence of S on the center angle a. The important value is the difference Aa betweenthe 'desired' center angle a and the 'falsified' center angle ß. Equating the resultingdifference Aa to theprecision of the center angle aa and referring to Table 5.2, it can be seen that, except for the implausibledeviation S of 10 °, all resulting differences Aa causes an error in the rotation time T of less than 1 /xs.Table 5.5: Difference Aa between 'desired' center angle a and falsified' center angle ß caused by a deflection angle5 using autocollimation. The longer the radius r and the smaller the deviation 5, the smaller the resulting differenceAa.r = Imr = 2mr = 5mS[°] 105 1 105 1 105 1a[°]1.41850.70930.28371.41850.70930.28371.41850.70930.2837ßl°]1.39700.69850.27941.41310.70660.28261.41830.70920.2837Aa[°] 0.0215 0.0108 0.0043 0.0054 0.0027 0.0011 0.0002 0.0001 0.0000The result of this discussion is that the autocollimation is well-adapted.The autocollimation can be carriedout with high accuracy. Here, the accuracy of autocollimation is further influenced by the precision of theorientation of the mirror mounted on the plate, cf. Figure 5.5. Furthermore, a sufficient precision for thecenter angle a can be achieved so that a time resolution, i.e. precision, for the rotation time T of 1 /xs ispossible.As described above, the most crucial parameter for the center angle a is the precision of the base ab-In ad¬dition to the precision of the base, the position of the reflection point on the autocollimation mirror also hasto be in the middle, between the two photo diodes. To determine this center point with high accuracy, theautocollimation mirror is covered with an adhesive tape. Only a small gap with a width of approximately1 mm is left in the middle. This setup allows for both sufficient central positions of the reflection pointrequired for autocollimation and a reflected laser beam necessary to perform the autocollimation. Further¬more, a scale is installed on the rotating mirror of the laser scanner. This scale includes a hole throughwhich the laser beam is emitted. The reflected laser beam hits the scale, and based on the position on thescale, the autocollimation mirror can be aligned perpendicular to the laser beam by means of the adjustingdevice. The autocollimation mirror is perpendicular to the laser beam if the reflected laser beam is overlaidwith the emitted laser beam. In Figure 5.7, on the left side the plate including the two photo diodes, theautocollimation mirror covered with the adhesive tape as well as the left gap, defining the position for theautocollimation, can be seen. On the right side, the scale fixed on the rotating mirror is shown.rotating mirrorcoverage ofautocollimation mirrorposition forautocollimationlaser beamscale forautocollimationFigure 5.7: Left: Arrangement of the two photo diodes and the coverage of the autocollimation mirror. Right: Scaleattached on the deflecting mirror of the laser scanner for measuring the offset between the emitting and reflecting laserbeams.
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DISS. ETH NO. 17036Calibration of a
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ZusammenfassungSeit einigen Jahren
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ContentsAbstractiiiZusammenfassungv
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Contentsix6.1.3 Results Ill6.2 Stat
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1Introduction1.1 Terrestrial Laser
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1.2 Motivation 3Precision [m10~1 "1
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6 1. Introduction
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8 2. Components of Terrestrial Lase
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10 2. Components of Terrestrial Las
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24 3. Calibration of Terrestrial La
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'28 3. Calibration of Terrestrial L
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"[m] of system 90%) 3540 distance b
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!36 3. Calibration of Terrestrial L
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138 3. Calibration of Terrestrial L
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Page 56 and 57: 46 3. Calibration of Terrestrial La
Page 68 and 69: Inormal axis,intersectionpoint axis
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Page 84 and 85: 74 4. Static Laser Scanning4.1.2 Mi
Page 86 and 87: 76 4. Static Laser ScanningOptical
Page 88 and 89: 78 4. Static Laser Scanningmaximum
Page 90 and 91: 80 4. Static Laser Scanningand gene
Page 92 and 93: 82 4. Static Laser Scanning• Ther
Page 94 and 95: 84 4. Static Laser Scanning4.3.3 NU
Page 96 and 97: 86 4. Static Laser Scanning
Page 98 and 99: 88 5. Kinematic Laser Scanningmirro
Page 100 and 101: 90 5. Kinematic Laser ScanningThe a
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Page 122 and 123: 112 6. Applications of Terrestrial
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Page 142 and 143: 132 7. Summaryrange, achievable by
Page 144 and 145: 134 7. Summary
Page 146 and 147: 136 A. Imaging System of Imager 500
Page 148 and 149: 138 B. Technical Data of Imager 500
Page 150 and 151: u140 C. Adjustment of SphereA =dfi,
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Page 154 and 155: 144 D. Electronic Circuit for Deter
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aMulti-SensorPlatform,PhDGeodesy Sw
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Accuracy-AeinTPS1200 AG, -Version 1
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-GenauigkeitsbetrachtungenInvestiga
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152 BibliographyWunderlich, T. A. [
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List of Figures3.22 Residuals of th
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156 List of Figures
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158 List of Tables
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200220072002Curriculum VitaePersona
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