双波长共相检测方法研究

Research on the method of co-phasing detection of two wavelengths

拼接镜共相检测技术是拼接过程和维持镜面质量关键技术之一,定量测量平移误差(piston)是指导拼接确定性调整的依据,也是拼接镜面成像质量、望远镜角分辨率的根本保证。为了实现拼接镜平移误差的大量程、高精度检测,提出了新型双波长共相检测算法,并基于圆孔衍射与双波长检测理论,推导得到了双波检测理论量程与波长之间的关系式以及选取模板间隔的最大值与波长之间关系式。在双波长检测中,针对两半圆间远场图案存在偏心、间隙误差和相机噪声等拼接误差,理论和仿真分析了间隙误差、偏心误差和相机噪声对双波长检测精度的影响。得到了间隙误差需小于0.2r,偏心误差需小于0.2r,信噪比需大于30时,双波长检测才不会出现误检测。该分析为以后双波长检测实验中误差的选取提供了借鉴。

The co-phasing detection technology of segmented mirror is one of the key of the segmented process and maintaining the quality of mirror. The quantitative measurement piston error is not only the chief gauge of the adjustment of segmented mirror, but also the guarantee of the segmented telescope ′ s imaging performance and the segmented telescope′s angular resolution. In order to realize the detection of lager range and high-precision of piston errors of segmented mirror, the new two-wavelengths co-phasing detection algorithm was raised in this paper. The relation between the theoretical detection range and the values of two wavelengths was got and the relation between the max value of template interval and the values of two wavelengths was got based on circular diffraction and the two wavelengths detection theory.In two wavelengths algorithm, the gap error, eccentric error and camera noise between two half circular diffraction patterns could influence the detection range and accuracy of two wavelengths algorithm, how the errors of gap, eccentric and camera noise influence the detection range and accuracy by theory and simulation were analyzed and got. And the gap error less than 0.2 r, the eccentric error less than 0.2 r and the Signal to Noise Ratio(SNR) of camera noise more than 30 were got, the two wavelengths detection will not cause false detection. The study on error sprovided reference for the co-phasing experiment of segmented mirror in two wavelengths algorithm.