From Event: SPIE Optical Engineering + Applications, 2018
To probe the molecular composition of a remote target, a laser is directed at a spot on the target, where melting and evaporation occur. The heated spot serves as a high-temperature blackbody source, and the ejected substance creates a plume of surface materials in front of the spot. Bulk molecular composition of the surface material is investigated by using a spectrometer to view the heated spot through the ejected plume. The proposed method is distinct from current stand-off approaches to composition analysis, such as Laser-Induced Breakdown Spectroscopy (LIBS), which atomizes and ionizes target material and observes emission spectra to determine bulk atomic composition. Initial simulations of absorption profiles based on theoretical models show great promise for the proposed method. This paper compares simulated spectral profiles with results of preliminary laboratory experiments. A sample is placed in an evacuated space, which is situated within the beam line of a Fourier Transform Infrared (FTIR) spectrometer. A laser beam is directed at the sample through an optical window in the front of the vacuum space. As the sample is heated, and evaporation begins, the FTIR beam passes through the molecular plume, via IR windows in the sidewalls of the evacuated space. Sample targets, such as basalt, are tested and compared to the theoretically predicted spectra.
Jonathan Madajian, Gary B. Hughes, Benton Miller, Yu Wang, Dane Brouwer, Alexander Cohen, Jessie Su, William Strickland, Prashant Srinivasan, Travis Brashears, Nicholas Rupert, and Philip Lubin, "Remote Laser Evaporative Molecular Absorption (R-LEMA) spectroscopy laboratory experiments," Proc. SPIE 10769, CubeSats and NanoSats for Remote Sensing II, 107690N (Presented at SPIE Optical Engineering + Applications: August 22, 2018; Published: 2 October 2018); https://doi.org/10.1117/12.2322105.
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