论文信息 - Performance analysis of a double-beam FTIR spectrometer used for passive standoff detection

Performance analysis of a double-beam FTIR spectrometer used for passive standoff detection

Since 1997, Defence Research and Development Canada - Valcartier (DRDC Valcartier) has been developing a Fourier-transform infrared (FTIR) spectrometer for the passive standoff detection of chemical clouds. This instrument, referred to as the Compact ATtmospheric Sounding Interferometer (CATSI), is a double-beam optically balanced FTIR spectrometer operating in the thermal infrared. The double-beam operation mode capability of the instrument is used to suppress the unwanted clutter radiance from the target's background. A methodology for determining the noise equivalent spectral radiance (NESR) of the CATSI instrument in laboratory conditions is presented, along with results using both the double-beam configuration, and a single-beam configuration in which the reference input port is blocked by a liquid Nitrogen-cooled patch, in order to simulate a standard FTIR spectrometer. NESR is found to be depart from the theoretical diminution with integration time due to measurement drifts, which persist even using frequent calibrations of the instrument. NESR evaluation is performed on the real and imaginary part of calibrated measurements after drift correction.

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