摘要
大视场高分辨率光谱成像系统往往伴随着严重的谱线弯曲,会大大增加光谱信息提取难度,降低系统获取信息的准确性,因此在光学设计过程中需要将谱线弯曲作为重要指标进行优化处理。针对这一问题,提出利用棱镜与光栅以棱镜+光栅+棱镜(P+G+P)的组合方式对谱线弯曲进行校正,结合该结构谱线弯曲特性以及色散特性,通过理论推导得到P+G+P色散模型,并建立P+G+P校谱线弯曲参数组合解算方法,最终解算并设计一套大视场高分辨率校谱线弯曲P+G+P光谱仪光学系统。该系统适用于温室气体探测中O2-A波段的探测,具有60 mm的长狭缝,工作波段为747~777 nm,并且系统具有较宽的色散谱面以达到高分辨率。最终设计与优化结果表明:系统色散谱面宽度达15 mm,平均光谱分辨率达0.0386 nm,在Nyquist频率为25 lp/mm处,全波段MTF(modulation transfer function)均优于0.6,RMS(root mean square)点列图小于12μm,最大视场处校正后的谱线弯曲小于1 pixel(20μm),色畸变接近0.5 pixel。该设计方法实现了对大视场高分辨率P+G+P光谱仪系统谱线弯曲的有效校正,使系统具有很好的成像质量。
Objective In imaging spectrometers for greenhouse gas detection,a large field of view(FOV)enables comprehensive monitoring across wide geographical or atmospheric volumes,supporting detailed spatiotemporal analysis of greenhouse gas concentrations and emission patterns.This broad coverage helps accurately identify greenhouse gas sources,providing essential data to locate and address emission points.A larger FOV enhances coverage,reduces revisit cycles,and improves the temporal resolution of the instrument.However,as the FOV increases,smile distortion and chromatic distortion become more prominent,which negatively affects spectral resolution,introduces misalignment in images,and complicates data processing tasks such as spectral radiometric calibration.Current methods for spectral line curvature correction focus primarily on two areas:calibration and optical design.While electronic calibration has shown effectiveness in mitigating smile distortion,it cannot resolve the underlying issues of spectral line curvature that influence detector efficiency and complicate pixel alignment,adding complexity to image processing.Optical design correction methods,although effective,often encounter difficulties in assembling and manufacturing optical components,especially when required to support a large FOV or instantaneous FOV systems.In this paper,we propose a novel design approach that leverages an algorithm to automatically generate prism-grating-prism(PGP)dispersion module parameters that meet performance requirements,achieving a large-field,high-resolution system with minimized smile distortion.Methods To develop a large-field,high-resolution spectrometer system with minimized smile distortion,we propose using a P+G+P dispersion model that combines prisms and grating.Based on the specific characteristics of smile distortion and the dispersion properties of this model,a theoretical derivation is conducted to build the P+G+P dispersion model.A parameter-solving method for correcting smile distortion within the P+G+P dispersion model is also developed.Finally,the proposed algorithm is applied to design a large-field,high-resolution spectrometer system utilizing the P+G+P dispersion model for smile distortion correction.Results and Discussions Based on the proposed solution for correcting smile distortion in large-field,high-resolution spectrometer systems using the PGP dispersion model,a PGP dispersion model is derived by analyzing the characteristics of smile distortion and dispersion.This includes a process to determine parameters specifically for correcting smile distortion.To validate the effectiveness of the approach,a large-field,high-resolution P+G+P spectrometer system is designed with a spectral range of 747-777 nm,a spectral resolution of 0.04 nm,and a slit length of 60 mm,making it suitable for detecting the O2-A band in greenhouse gas monitoring(Table 1).For this system,the collimator group uses an off-axis three-mirror anastigmatic structure with aspheric mirrors,while the imaging group combines spherical and aspherical lenses in a transmission structure.The design results show that the system achieves a dispersed spectrum width of 15 mm across a 30 nm spectral range,with an average spectral resolution of 0.0386 nm,exceeding the design requirement of 0.04 nm(Fig.12).At a Nyquist frequency of 25 lp/mm,the modulation transfer function(MTF)across the full spectral range is greater than 0.6(Fig.10),while the root mean square(RMS)spot size remains below 12μm(Fig.11).The corrected smile distortion at the maximum FOV is less than 1 pixel(20μm)(Fig.13),and the keystone distortion is approximately 0.5 pixel(20μm)(Fig.14).Conclusions The design proposed in this study offers several advantages,including easier realization of a large FOV,reduced spectral line curvature,and streamlined fabrication processes.The proposed design approach for large-field,highresolution systems with smile distortion correction is universally applicable to P+G+P dispersion model spectrometers.In this paper,we establish a complete design process and methodology for large-field,high-resolution P+G+P spectrometers with spectral line curvature correction,enabling faster identification of optimal system parameters across various specifications.This significantly shortens the design cycle and improves design efficiency.The large-field,highresolution P+G+P spectrometer designed here effectively corrects the severe spectral line curvature typically associated with large-field systems,without adding complexity.Compared to traditional large-field P+G+P spectrometers,the FOV is increased by 250%.The final design achieves a dispersed spectrum width of 15 mm over a 30 nm spectral range,with an average spectral resolution of 0.0386 nm.At the maximum FOV,smile distortion is maintained below 1 pixel,ensuring excellent imaging quality.
作者
郑强
郑玉权
蔺超
张佳伦
Zheng Qiang;Zheng Yuquan;Lin Chao;Zhang Jialun(Changchun Institute of Optics,Fine Mechanics and Physics,Chinese Academy of Sciences,Changchun 130033,Jilin,China;University of Chinese Academy of Sciences,Beijing 100049,China;State Key Laboratory of Applied Optics,Changchun 130033,Jilin,China;Key Laboratory of Advanced Manufacturing for Optical Systems,Chinese Academy of Sciences,Changchun 130033,Jilin,China)
出处
《光学学报》
北大核心
2025年第2期254-263,共10页
Acta Optica Sinica
基金
国家重点研发计划(2022YFB3904804)。
