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

Yupeng Chen,Jinguang Lv,Yuxin Qin,Baixuan Zhao,Jingqiu Liang,Jin Tao,Weibiao Wang

doi:10.1109/access.2021.3090963

Abstract

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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3.7~\mu \text{m}$ </tex-math></inline-formula> to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4.8~\mu \text{m}$ </tex-math></inline-formula> . 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 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> CN) and carbon dioxide (CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) were measured, the experimental results show that the spectral peak drift errors were found to be less than 0.18%.

Highlights

Fourier transform spectrometers (FTSs) have the advantages of being multichannel and having a high throughput
In response to the urgent need for miniaturization of static Fourier transform spectrometer (SFTS) devices for online monitoring and transient-target spectrum measurements, in this paper, we propose a medium-wave infrared SFTS based on micro-optical elements
We performed spectrummeasurement experiments, and the results demonstrate that the measured spectra of CH3NH and CO2 almost completely coincide with the reference spectra from a commercial FTS system; This demonstrates that the micro-optical element static Fourier transform spectrometer (MOESFTS) system is capable of performing medium-wave broad infrared spectrum measurements of liquids and gases

Summary

Introduction

Fourier transform spectrometers (FTSs) have the advantages of being multichannel (the Fellgett advantage) and having a high throughput (the Jacquinot advantage). They are widely used in the biopharmaceutical, food safety, and environmental-monitoring fields [1]–[8]. The continuous advancement of science and technology has gradually improved the performance of FTSs; various fields have put forward an urgent requirement for real-time online measurement of spectra in emergency situations and severe environments. While traditional temporal-modulation FTSs continue to be developed, attention has been paid to the original method of static spatial-modulation FTS measurements. Developments have focused on decreasing the size and weight of the instruments to further adapt them to the application requirements of real-time online monitoring [9]–[12]

Methods

Results

Conclusion