title: Raman efficiencies of natural rocks and minerals: performance of a remote Raman system for planetary exploration at a distance of 10 meters.
abstract: Raman spectroscopy is a powerful technique for materials analysis, and we are developing and analyzing a remote Raman system for use on a planetary lander or rover. We have acquired data at a distance of 10m from a variety of geologic materials using different instrument designs. We have employed a pulsed laser with both an ungated detector and a gated detector. A gated detector can reduce long-lived fluorescence while still collecting all Raman signal. In order to design a flight instrument, we need to quantify how natural surfaces will respond to laser stimulus. We define remote Raman efficiency of natural surfaces as the ratio of radiant exitance leaving a natural surface to the irradiance of the incident laser. The radiant exitance of a natural surface is the product of the sample radiance, the projected solid angle, and the full-width-half-maximum of the Raman signal. We have determined the remote Raman efficiency for a variety of rocks and minerals. The best efficiencies are achieved for large, clear, single crystals that produce the most radiant exitance, while darker fine-grained mineral mixtures produce lower efficiencies. By implementing a pulsed laser, gated detector system we have improved the signal detection and have generally decreased the integration time necessary to detect Raman signal from natural surfaces.
authors: Hawaii Institute of Geophysics and Planetology, University of Hawaii, 1680 East-West Road, Post 504, Honolulu, HI 96822, USA. jstopar@higp.hawaii.edu
authors: Julie D
authors: JD
authors: Stopar
authors: Paul G
authors: PG
authors: Lucey
authors: Shiv K
authors: SK
authors: Sharma
authors: Anupam K
authors: AK
authors: Misra
authors: G Jeffrey
authors: GJ
authors: Taylor
authors: Hugh W
authors: HW
authors: Hubble
mesh_terms: D003627:Data Interpretation, Statistical; D005118:Extraterrestrial Environment; D018535:Mars; D012371:Robotics; D017640:Silicates / Q000737:chemistry; D013059:Spectrum Analysis, Raman / Q000295:instrumentation
chemical_list: D017640:Silicates