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 (CH
₃
CN) and carbon dioxide (CO
₂
) were measured, the experimental results show that the spectral peak drift errors were found to be less than 0.18%.