Mary Masterman - Oklahoma Biological Survey - University of ...
Mary Masterman - Oklahoma Biological Survey - University of ... Mary Masterman - Oklahoma Biological Survey - University of ...
Conclusion and Recommendations 10 In the end, a Raman spectrograph system was successfully constructed. The process of building the Raman head was difficult, especially the optical alignment, and only through trial and error were Raman spectra finally achieved. The Littrow spectrograph (attached to the Raman head) still proved to be more difficult to construct than the Raman head due to the even more complicated process of optical alignment associated with the diagonal mirror between the collimation lens and the camera chip. Optical alignment of the Raman system was difficult due to the faintness of the Raman signal (it is invisible to the naked eye, so it is difficult to get the signal aligned on the slit of the spectrograph). The difficulty associated with accounting for the small backfocus of my digital camera proved to be a severe problem. The Littrow spectrograph produced spectra that were higher resolution than the classical spectrograph constructed in my previous project; however, all in all, I would say that the difference in resolution and spectral dispersion were not worth the added trouble of building and collimating the new spectrograph. Still, the idea that Raman spectrographs—high or low resolution ones—might be someday constructed for very wide-ranging industrial applications and for a relatively small cost is very exciting. In the future I would like to create a program to quicken data analysis of spectra produced by the Raman system, and even write a program to use least-squares analysis to automatically determine the composition of compounds using a library of Raman spectra of common compounds. I would also like to examine the relationship between compound concentration and intensity of the Raman signal, which theoretically are directly proportional. This will require a carefully alignable sample holder, with a constant thickness, since the Raman signal varies depending on how much of the sample the laser light passes through. I would like to experiment with the sample holder and the laser alignment to see if the Raman signal can be maximized. Raman spectroscopy has an amazingly diverse array of applications in society, including analysis of synthetic polymers like rubber, identification of legal and illegal drugs (forensics) and identification of explosives, determination of unsaturation in food oils and fats, determination of defects in semiconductors; in-situ measurements of rocks and minerals during planetary missions, real-time detection / diagnosis of cancer, and analysis of artwork. These applications pose a seemingly unlimited number of potential project ideas, and emphasize the significance that amateur Raman spectroscopy could have on the entire field.
11 Acknowledgement I would like to thank Chroma Corporation for courteously donating me a set of Raman filters, including a dichroic mirror, barrier filter, and excitation filter, for use in my research; without these filters, my project probably would not even have been possible. I would also like to thank Alan Holmes and the Santa Barbara Instrument Corporation for letting me borrow an ST-10 CCD camera for future use with my project. I wish to thank Dr. Roger Freck of the Chemistry Department at the University of Oklahoma for taking the time to explain the fundamentals of vibrational spectroscopy to me and clearing up all of my misconceptions about Raman spectroscopy. I would like to thank the IAPPP (International Amateur Photoelectric Photometry) and the AAS (American Astronomical Society) for granting me and my partner Sarah Howell the Richard D. Lines award last year, which helped to fund my project this year. I would also like to thank Mr. Jeffrey Baughman for helping me with all of the advice he offered me concerning my project and his immense help with regards to the forms and other technicalities required. I would most like to thank my parents for their support, specifically my dad, who taught me how to use AutoCAD to design my spectrograph and instructed me in the difficult process of machining the parts for my spectrograph.
- Page 1 and 2: Construction and Operation of a Ram
- Page 3 and 4: 3 Introduction Objectives • To co
- Page 5 and 6: Barrier filters may be Long-Wave-Pa
- Page 7 and 8: Fig. 4 - My diagrams of spectrograp
- Page 9: Discussion of Results 9 Eventually,
Conclusion and Recommendations<br />
10<br />
In the end, a Raman spectrograph system was successfully constructed. The process <strong>of</strong> building the Raman head was difficult,<br />
especially the optical alignment, and only through trial and error were Raman spectra finally achieved. The Littrow spectrograph<br />
(attached to the Raman head) still proved to be more difficult to construct than the Raman head due to the even more complicated<br />
process <strong>of</strong> optical alignment associated with the diagonal mirror between the collimation lens and the camera chip. Optical<br />
alignment <strong>of</strong> the Raman system was difficult due to the faintness <strong>of</strong> the Raman signal (it is invisible to the naked eye, so it is<br />
difficult to get the signal aligned on the slit <strong>of</strong> the spectrograph). The difficulty associated with accounting for the small backfocus<br />
<strong>of</strong> my digital camera proved to be a severe problem. The Littrow spectrograph produced spectra that were higher resolution than the<br />
classical spectrograph constructed in my previous project; however, all in all, I would say that the difference in resolution and<br />
spectral dispersion were not worth the added trouble <strong>of</strong> building and collimating the new spectrograph. Still, the idea that Raman<br />
spectrographs—high or low resolution ones—might be someday constructed for very wide-ranging industrial applications and for a<br />
relatively small cost is very exciting.<br />
In the future I would like to create a program to quicken data analysis <strong>of</strong> spectra produced by the Raman system, and even write<br />
a program to use least-squares analysis to automatically determine the composition <strong>of</strong> compounds using a library <strong>of</strong> Raman spectra<br />
<strong>of</strong> common compounds. I would also like to examine the relationship between compound concentration and intensity <strong>of</strong> the Raman<br />
signal, which theoretically are directly proportional. This will require a carefully alignable sample holder, with a constant thickness,<br />
since the Raman signal varies depending on how much <strong>of</strong> the sample the laser light passes through. I would like to experiment with<br />
the sample holder and the laser alignment to see if the Raman signal can be maximized.<br />
Raman spectroscopy has an amazingly diverse array <strong>of</strong> applications in society, including analysis <strong>of</strong> synthetic polymers like<br />
rubber, identification <strong>of</strong> legal and illegal drugs (forensics) and identification <strong>of</strong> explosives, determination <strong>of</strong> unsaturation in food<br />
oils and fats, determination <strong>of</strong> defects in semiconductors; in-situ measurements <strong>of</strong> rocks and minerals during planetary missions,<br />
real-time detection / diagnosis <strong>of</strong> cancer, and analysis <strong>of</strong> artwork. These applications pose a seemingly unlimited number <strong>of</strong><br />
potential project ideas, and emphasize the significance that amateur Raman spectroscopy could have on the entire field.
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