Medium-Wave Infrared Static Fourier Transform Spectrometer Based on Micro-Optical Elements

In recent years, various fields have established an urgent need for real-time online measurement of infrared spectra. To this end, reducing the weight and size of infrared spectrometers is particularly important. This paper reports a micro-optical element static Fourier transform spectrometer (MOESFTS) with a working wavelength from $3.7~\mu \text{m}$ to $4.8~\mu \text{m}$ . This spectrometer is entirely composed of micro-optical elements, and its interference system comprises stepped micromirrors and a lightweight beam splitter to realize a lightweight, miniaturized instrument capable of static real-time spectrum measurements. The micro-optical element microlens array leads to the acquisition of interferogram in the form of two-dimensional point-array in the MOESFTS. Therefore we establish a field-of-view integral model of the interference-image point intensity to analyze the influence of the field of view on the reconstructed spectrum. We complete the optical design of the micro-optical collimator (MOC) lens and the micro-optical relay (MOR) lens. And an effective processing algorithm for spectral reconstruction from two-dimensional point-array is presented. A prototype was designed and constructed, and spectral calibration was completed. The spectra of acetonitrile (CH3CN) and carbon dioxide (CO2) were measured, the experimental results show that the spectral peak drift errors were found to be less than 0.18%.