在平场凹面全息光栅的设计制作中, 不可避免的存在曲率半径误差, 严重影响光栅光谱仪的分辨率。 为了从理论上分析并指导光谱仪器的设计和装调, 运用几何光线追迹方法计算并分析了不同曲率半径误差下光谱像宽度的变化规律, 发现在一个较大的误差范围内子午焦线的位置随着曲率半径的变化前后平移, 同时其弯曲程度几乎没有改变。 数值计算发现通过调整像面位置或入臂长度均能够补偿曲率半径的误差。 数值模拟结果显示, 修正使用结构后的光栅能够达到与设计结果相近的成像质量。

The spectral resolution of the spectrometer will be seriously deteriorated by radius error which is inevitable in the flat-field holographic concave grating fabrication. In order to give theoretical guidance to the design and assembly of the spectrometers, the geometric ray-tracing method was used to calculate and analyze the variation of the spectral image width with different radius error. It was discovered that in a wide range of the radius error, the position of the tangential focal curve moves forward or backward as the radius changes, while the shape of the tangential focal curve remains almost unchanged. As is shown through the calculation, the radius error can be compensated by adjustment of the detector's position or entrance slit distance. The simulation results indicate that with proper modification of the using structure, the grating can have a spectral resolution as good as the designed results.