| 摘要 |
Light from a discrete broadband visible and/or infrared light source is collimated and transmitted within an optical path that is open to an ambient environment through a spatial region of interest and is focused to a beam splitter, which splits the transmitted light into different beams and directs the different beams respectively to a pair of narrowband acousto-optical tunable filters (AOTF). One such AOTF is disposed for filtering one split transmitted light beam and is rapidly tuned through a predetermined series of different wavelengths that are characteristic of an energy absorption spectrum for a first given substance, or of a first predetermined set of given substances. The other AOTF is disposed for filtering the other split transmitted light beam and is rapidly tuned through a given substances. First and second detectors respectively detect the energy of the filtered transmitted light from the two AOTFs at each of the tuned wavelengths to provide simultaneous signals that are indicative of energy absorption spectra for the region of interest at wavelengths that are characteristic of the energy absorption spectra for the first and second given substances or for the first and second predetermined sets of given substances.
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