大孔径空间外差干涉光谱成像技术多谱段成像仿真

Simulation of multiband imaging technology of large aperture spatial heterodyne imaging spectroscopy

在大孔径空间外差干涉光谱成像技术(LASHIS)的基础上提出了一种多谱段成像方案.其采用LASHIS的外差探测原理,一方面,可通过较少的采样点数实现很高的光谱分辨率,保留了LASHIS的高光谱分辨率、高稳定性和高探测灵敏度的特点;另一方面,利用光栅的多级衍射性质,实现同一系统的多谱段同时探测,拓宽了光谱探测范围.首先,阐述了LASHIS多谱段成像方案的基本原理;然后,分析了多谱段探测与谱段解混方式;最后,对该方案进行了计算机仿真模拟,通过ZEMAX光线追迹的干涉图结果与理论计算结果相符合,验证了方案的正确性.基于LASHIS的多谱段成像方案所具有的高光谱分辨率、高探测灵敏度以及可实现同一系统的多谱段同时探测特点,尤其适合温室气体等高稳定性、高探测灵敏度的多谱段高光谱探测应用.

A multiband imaging technology based on large aperture spatial heterodyne imaging spectroscopy (LASHIS)is proposed in this paper.It retains the advantages of high spectral resolution,high stability and high detection sensitivity of LASHIS.In addition,by using the multistage diffraction gratings,several spectral bands can be detected simultaneously in this system,thus the spectral range is broadened.The basic principle of this multiband imaging technology based on LASHIS is described.The difference between optical path differences produced by the Sagnac lateral shearing interferometer and the parallel gratings is calculated.The mathematical expressions,the interferogram calculation procedures,and the spectrum reconstruction method are presented.As a pair of multistage diffraction gratings is introduced into the Sagnac interferometer,the rays of different diffraction orders corresponding to different spectral bands are mixed together in the interferometer.The spectral bands should be separated before they are imaged on the detector.Two separation methods are proposed:introducing a filter array in front of the detector and introducing dichroic mirrors to assign different spectral bands to different detectors.Finally,a design example is given and an optical model is setup in ZEMAX.In this example,a pair of parallel echelon gratings with 316lines/mm is introduced into the Sagnac.interferometer.Two dichroic mirrors and three detectors are used to separate and detect three spectral bands simultaneously.The three spectral ranges are from 529.2nm to 532.96nm,from 588nm to 592.18nm,and from 661.5nm to 666.20nm.The average spectral resolutions are 0.015nm,0.016nm,and 0.018nm respectively.Two kinds of sources are analyzed:one is a sodium lamp with two emission peaks at 589nm and 589.6nm,and the other is a source with three monochromatic wavelengths at 530nm,589nm,and 662nm.The interferograms of these two sources traced in the optical model are consistent with the theoretical results.The recovered spectra show good agreement with the input spectra.These verified the correctness of the principle and the spectrum reconstruction method.The multiband imaging technology based on LASHIS with the advantages of high spectral resolution,high detection sensitivity,and multiband detection capability,is especially suitable for multiband hyperspectral highstability and high-sensitivity detection,such as the detection of greenhouse gases.