Broadband high-resolution static infrared Fourier transform spectrometer based on grism dispersion and micromirror interference coupling

This paper proposes a static infrared Fourier transform spectrometer based on the cooperative operation of grisms and a stepped micromirror, termed the GSM-FTS. The system achieves simultaneous spectral detection with broad spectral coverage and high resolution in a single snapshot. Its compact coaxial parallel dispersion unit avoids additional optical path deflection. By applying synchronous spatial phase modulation to the full spectral band along the direction perpendicular to dispersion, the system reduces the interference sampling frequency by nearly two orders of magnitude and thus achieves a breakthrough in spectral resolution. This paper presents a design example with a spectral detection range from 2.98 μm to 5.18 μm and a spectral resolution of 0.45 cm -1 . The influence of dispersion crosstalk and stepped micromirror surface deviation on spectral detection performance is analyzed. Experimental verification of the practical performance of the GSM-FTS is provided, together with identification tests of characteristic absorption peaks for common pollutant gases.