Deep UV Raman Spatial Heterodyne Spectrometer for Depth Resolved Core Analysis

Physical Sciences Inc. (PSI) will develop a compact, solid-state ultraviolet spatially offset Raman sensor with a diagnostic core retrieval system. The UV Raman sensor, currently under development at PSI, utilizes a UV laser (266 nm) that has been developed by Q-Peak (a division of PSI) for a previous NASA SBIR. The Raman sensor will also use a high throughput spatial heterodyne interferometric spectrometer (SHS). The SHS is 104 more sensitive to Raman photons than a conventional diffraction grating based slit-spectrometer operating with the same spectral resolution in the UV. In addition, the proposed UV Raman system utilizes the Rayleigh scattering law for Raman scatter at shorter wavelengths. The current UV Raman design will be modified to include a digital micromirror device (DMD) in order to collect spatially offset Raman signal (SORS) at varying penetration depths within a material. This system will be paired with a small core retrieval system in order to measure depth resolved Raman spectra within samples. This will allow for initial diagnostic testing of areas on small bodies, such as comet nuclei, to determine where larger cores should be collected and returned to Earth. Depth resolved measurements will be more indicative of volatiles trapped within the material that might vaporize off the surface during collection and avoids contamination that can occur at the surface. The Phase I effort will focus on functional testing of the SORS breadboard with the UV laser. In parallel, the Phase I will design a prototype core retrieval system, in order to better inform the final design for a Phase II prototype.nbsp;