Design, development, and testing of a stochastically modulated Raman spectrometer
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2019
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| Format: | Thesis |
| Language: | eng |
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Massachusetts Institute of Technology
2019
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| Online Access: | https://hdl.handle.net/1721.1/122508 |
| _version_ | 1826193183892045824 |
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| author | Zervas, Michael Jay. |
| author2 | Ian W. Hunter. |
| author_facet | Ian W. Hunter. Zervas, Michael Jay. |
| author_sort | Zervas, Michael Jay. |
| collection | MIT |
| description | Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2019 |
| first_indexed | 2024-09-23T09:35:21Z |
| format | Thesis |
| id | mit-1721.1/122508 |
| institution | Massachusetts Institute of Technology |
| language | eng |
| last_indexed | 2024-09-23T09:35:21Z |
| publishDate | 2019 |
| publisher | Massachusetts Institute of Technology |
| record_format | dspace |
| spelling | mit-1721.1/1225082019-11-22T03:37:43Z Design, development, and testing of a stochastically modulated Raman spectrometer Zervas, Michael Jay. Ian W. Hunter. Massachusetts Institute of Technology. Department of Mechanical Engineering. Massachusetts Institute of Technology. Department of Mechanical Engineering Mechanical Engineering. Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2019 Cataloged from PDF version of thesis. Includes bibliographical references (pages 133-139). Detection of cancerous tumors and identification of counterfeit medications are just two examples that demonstrate the chemical specificity provided by Raman Spectroscopy. Yet, the widespread use of Raman Spectroscopy as an analytical tool has been limited to large bench-top systems in controlled laboratory environments. Existing technology, specifically in portable or handheld formats, suffers from a high false detection rate and relatively low sensitivity compared to other spectroscopic techniques. The present work addresses these issues through the design and development of a new system architecture that stochastically modulates the laser excitation wavelength. Small changes in excitation will proportionally shift the Raman scatter while having little effect on other spectral artifacts, including fluorescence. A custom confocal Raman Spectrometer was built and characterized that can rapidly shift the excitation wavelength by selectively straining an externally mounted Fiber Bragg Grating (FBG). When combined with a super-luminescent diode (SLED), a modulation bandwidth of over half a nanometer was achieved. The functionality of the system was tested and benchmarked against Raman spectra that have been well characterized in literature. In addition, a novel signal processing approach was used to obtain a difference spectrum from a stochastic input excitation sequence. Simulations were conducted that compare the performance to conventional methods, which were then verified experimentally. Results indicate that the stochastic modulation was able to effectively isolate Raman scatter with a higher SNR compared to conventional methods. Finally, it was demonstrated that the developed system could be applied to Surface Enhanced Raman Spectroscopy (SERS). SERS substrates increase the Raman scatter signal, but also compete with significant fluorescence and a strong background signal. Rhodamine 6G, a fluorescent dye, was tested using the developed system on a SERS substrate. Concentrations on the order of several hundred parts per million (ppm) were successfully measured, with significantly lower limits of detection possible. The experimental data shows that the combination of SERS with stochastically modulated techniques reduces the false detection rate and improves the detection sensitivity by several orders of magnitude, addressing both of the major existing limitations. by Michael J. Zervas. Ph. D. Ph.D. Massachusetts Institute of Technology, Department of Mechanical Engineering 2019-10-11T21:53:47Z 2019-10-11T21:53:47Z 2019 2019 Thesis https://hdl.handle.net/1721.1/122508 1121202109 eng MIT theses are protected by copyright. They may be viewed, downloaded, or printed from this source but further reproduction or distribution in any format is prohibited without written permission. http://dspace.mit.edu/handle/1721.1/7582 139 pages application/pdf Massachusetts Institute of Technology |
| spellingShingle | Mechanical Engineering. Zervas, Michael Jay. Design, development, and testing of a stochastically modulated Raman spectrometer |
| title | Design, development, and testing of a stochastically modulated Raman spectrometer |
| title_full | Design, development, and testing of a stochastically modulated Raman spectrometer |
| title_fullStr | Design, development, and testing of a stochastically modulated Raman spectrometer |
| title_full_unstemmed | Design, development, and testing of a stochastically modulated Raman spectrometer |
| title_short | Design, development, and testing of a stochastically modulated Raman spectrometer |
| title_sort | design development and testing of a stochastically modulated raman spectrometer |
| topic | Mechanical Engineering. |
| url | https://hdl.handle.net/1721.1/122508 |
| work_keys_str_mv | AT zervasmichaeljay designdevelopmentandtestingofastochasticallymodulatedramanspectrometer |