Stand-off Raman detection using dispersive and tunable filter based systems.

Small, transportable Raman systems are being developed for stand-off Raman measurements at intermediate ranges (e.g. <20 m) for planetary measurements. Four variations of stand-off Raman systems are described that use a small telescope for light collection that is either fiber-optic or lens-coupled to a detection system. The performance of an acousto-optic tunable filter for wavelength selection and spectral imaging is tested by comparing signal-to-noise ratio and throughput to similar measurements using a conventional spectrograph, and by measuring a variety of organic and inorganic mineral samples at distances up to 15 m. We also determine optimal ICCD gate widths for acquiring remote Raman spectra under high ambient light conditions.