基于干涉条纹傅里叶分析技术对拼接光栅调整偏角的计算分析  

Fourier-Transform Method for Analyzing Angular Errors from Interferograms for Mosaic Grating Alignment

作　　者：韩建[1,2] 姜明达[1,2] 张凯[1,2] 肖东[1,2] 朱永田[1,2] Han Jian;Jiang Mingda;Zhang Kai;Xiao Dong;Zhu Yongtian(Natiomal Astronom ical Obseroatories/Nanjing Institute of Ast ronomical Optics&Technology,Chinese Academy of Sciences,Nanjing,Jiangsu 210042,China;CAS Key Laboratory of Astronomical Optics&Technology,Nanjing Institute of Astronomical Optics&Technology,Nanjing,Jiangsu 210042,China)

机构地区：[1]中国科学院国家天文台南京天文光学技术研究所,江苏南京210042 [2]中国科学院天文光学技术重点实验室(南京天文光学技术研究所),江苏南京210042

出　　处：《中国激光》2021年第3期120-129,共10页Chinese Journal of Lasers

基　　金：国家自然科学基金(11673046,11873071,11773047,11803059);国家自然科学基金联合基金重点项目(U2031211);中国科学院国际合作局对外合作重点项目(114A32KYSB20160049)。

摘　　要：阶梯光栅共相拼接技术是实现增大光栅尺寸、进一步提高天文光谱分辨率(天文光谱分辨率R>105)的关键。为了提高中阶梯拼接光栅的调整角度精度,本文基于干涉条纹傅里叶分析,提出了一种干涉条纹空间载频频率的九像素平均算法;然后结合干涉条纹光栅拼接技术,模拟了不同角度偏差下的条纹变化及其相应的傅里叶分析角度计算,在实验上实现了对系统角度调整系数的标定以及对傅里叶算法计算的调整偏角精度的分析,获得了拼接光栅调整系统中角度最大计算误差精度小于0.4μrad的结果,为天文上应用的大尺寸拼接光栅的共相调节提供了理论支持。Objective The current maximum size of a diffraction grating is a ruled area of 300 mm(groove length) by 400 mm(ruled width).With the latest generation of eight-and ten-me ter-class optical telescopes and the desire for resolutions exceeding 100000 for spectroscopic applications,there is a need to produce larger diffraction gratings or assemblies of existing gratings in good alignment.At the same time,descriptions of instrumentation utilizing such large gratings are found in the chirped-pulse-amplification(CPA) scheme.To overcome the current size limit for ruled gratings,a method is required for producing a stable assembly of two or more gratings.The most obvious choice is to build a fixture that can hold individual gratings in a stable configuration relative to one another and relative to the instrument where the gratings are being used.The alignment requirements for mosaic echelle gratings are derived from the image-quality requirements for a high-resolution spectrograph.Several schematic setups have been used to build alignment collimators of the echelle mosaic.Image analysis,as well as the logging of all data,is typically important for achieving the required level of noise reduction.The errors of the mosaic gratings can be analyzed quantitatively,enabling the experiment to succeed more effectively.Methods The alignments in a mosaic grating are determined by maintaining a reference grating in a static position and moving the adjustable gratings relative to the reference tile.There are five degrees of freedom relative to the reference grating:the tilt Δθy,tip Δθx,twist Δθz,lateral shift Δx,and piston extension Δz.All these alignment errors produce different fringes,so the properly aligned position can be determined by interferometric analysis.In order to increase the precision of the angular-error adjustments in mosaic grating alignment,we use nine-pixelaverage algorithm based on Fourier-transform to analyze the interference-fringe frequency patterns with high precision.The algorithm contains several ste

关 键 词：相干光学 拼接光栅 傅里叶变换 共相调节 调整精度 

分 类 号：P111.2[天文地球—天文学]