David M. Kuehn

Infrared acousto-optic tunable filter point spectrometer for detection of organics on mineral surfaces

Abstract. A prototype infrared (IR) acousto-optic tunable filter (AOTF)-based point spectrometer has been designed for examining and analyzing potential biological samples collected in situ from the planets or other solar system objects. The reflectance spectrometer operates at a wavelength range of 1.6 to 3.6 μm, which is diagnostic of minerals and organics, and inspects a 1-mm sized spot on the sample. The tuning component is the AOTF that has been utilized in a variety of spectral detection applications. The instrument’s specification and design approach including the selected components is described. The data acquisition system, the electronic components, and their interconnections are presented. The instrument’s radiometric performance is examined and described by a noise equivalent reflectance value of 0.13% that is obtained from the laboratory measurements. The device has been demonstrated by measuring the reflectance spectra for a variety of geological samples and comparing the results with the United States Geological Survey data.