Date of Award

Spring 2021

Document Type

Open Access Dissertation

Department

Chemistry and Biochemistry

First Advisor

S. Michael Angel

Abstract

Raman spectroscopy is a vibrational technique that provides detailed molecular and structural information for organic and inorganic molecules and minerals, and is uniquely suited for spacecraft applications, in the search for chemical indicators of life. This is why NASA sent two Raman spectrometers to Mars on the Mars 2020 Perseverance rover, as part of the SuperCam and SHERLOC instruments. The Raman spectrometers on Perseverance are conventional dispersive instruments that have been engineered to survive the harsh conditions of spaceflight. Future missions could benefit from smaller, more robust designs, especially missions to the Jovian planets, Jupiter and Saturn, their moons, asteroids and comets. The spatial heterodyne Raman spectrometer (SHRS) is one such spectrometer that has the potential to fit these needs. The SHRS is a Fourier transform interferometer with no moving parts that is capable of high spectral resolution, large spectral range, and very high light throughput as compared to dispersive slit-based spectrometers. And its design is compatible with monolithic construction techniques.

This work describes a monolithic spatial heterodyne Raman spectrometer (mSHRS), where the optical components of the spectrometer are bonded to make a small, stable, one-piece structure. The mSHRS is very compact, measuring about 3.5 x 2.5 x 2.5 cm in size and weighing about 80 g. When compared to previously described free standing SHRS, the mSHRS was found to be more stable, have higher SNR, a large spectral range, and higher spectral resolution, and provided high SNR using CMOS camera detectors. The small size and high light throughput of the mSHRS makes it suitable for use with small platforms such as commercial drones, using the drone’s CMOS cameras as the detector. In drone studies, we found the performance of the mSHRS to be comparable to lab bench top measurements and the wide field of view of the mSHRS allowed measurements without the use of any collection optics, other than the drone camera lens. For some drone tests, an optical fiber was used to deliver the laser light to the sample, also possible because of the large field of view of the mSHRS.

Rights

© 2021, Abigail M. Waldron

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