A method of using the SIMS (the Selective Modulation Interferometric Spectrometer) to measure the difference between the spectral content of two optical beams is given. The differ - encing is done optically; that is, the modulated detector signal is directly proportional to the difference between the two spectra being compared. This optical differencing minimizes the dynamic -range requirements of the electronics and requires only a simple modification of the basic cyclic SIMS spectrometer. This technique can be used to suppress background radiation for the enhancement of target detection and tracking. Laboratory measurements demonstrating the application of this technique are reported.
Vanasse, George A.; Esplin, Roy W.; and Huppi, Ronald J., "Selective Modulation Interferometric Spectrometer (SIMS) Technique Applied to Background Suppression" (1979). Space Dynamics Lab Publications. Paper 136.