I型全息凹面光栅制作误差对光谱像的影响分析

Effect of Recording Parameters Error on Imaging Performance of Type I Holographic Concave Gratings

通过对I型全息凹面光栅制作参量误差对光谱像的影响进行数值计算发现:1)两记录臂长的相对误差而不是绝对误差决定光谱像的展宽程度,即使绝对误差较大,只要两记录臂长的误差值相同,像宽也没有明显改变;2)由于I型光栅的记录臂一般较长,记录角度误差对像宽的影响不大,但会影响光栅的刻线密度,导致光谱成像位置的偏移;3)曲率半径误差对像宽的影响较大.通过数值模拟明确了I型全息凹面光栅制作的误差容许范围,找到了对光谱像宽度影响较大的误差来源,从而为此类光栅的制作提供理论指导,有助于制作出高质量光栅,降低罗兰圆光谱仪的调节难度.

The imaging performance of type I holographic concave gratings would be seriously deteriorated by the recording parameters error during fabrication of the gratings.A numerical simulation was made for analyzing the effect of recording parameters error on imaging performance of the grating.The following conclusions can be obtained from the simulation results.Firstly,the larger the difference between errors of the two recording distances,the worse the imaging performance becomes.Secondly,the recording angle error remains very small because the recording distances for type I gratings are usually very long.The image widths would not change significantly.But the locations of the images would change because the grating constant is different from the desired value.Finally,it is very important to make the curvature radius as close to the namely value as possible,because the radius error would greatly deteriorated the focusing abilities of the gratings.This study can give theoretical guidance to the fabrication for type I holographic concave gratings and reduce the alignment difficulty for the Rowland circle spectrographs.