Signal-to-noise ratio of the spatially modulated imaging spectrometer based on modified Sagnac interferometer

The basic principle of the spatially modulated imaging spectrometer, based on modified Sagnac interferometer, is outlined. According to radiometry, electromagnetism and Fourier transform spectroscopy, the radiation flux received by each pixel of the detector is calculated, and then the exact expression of the signal-to-noise ratio (SNR), at a distance x away from the zero-order fringe, is given. To analyze and discuss the effects of various parameters on SNR, the computer simulation is carried out, and some important conclusions are obtained. Using the root mean square method, the SNR variations of the whole optical system, changing with Sagnac interferometer acute angles β1 and β2, are simulated, and the condition β1=β2 can make the system SNR higher and more stable. This work can provide theoretical basis and practical guidance for improving the spatially modulated imaging spectrometer’s SNR together with its engineering realization.