大孔径面视场PG成像光谱仪的光学设计

针对成像光谱仪通过狭缝进行线视场成像时存在的孔径较小、光学透过率较低等问题,研究了一种基于棱镜-光栅型分光结构的大孔径面视场成像光谱仪。该棱镜-光栅成像光谱仪采用表面浮雕型透射光栅,极大地降低了光栅的制作难度与成本。大孔径面视场的成像光谱仪相较于线视场成像光谱仪有较高光学效率和时间效率。但是面视场成像光谱仪的色畸变与谱线弯曲较难校正。本文将前端望远系统与分光系统进行一体化设计,满足远心光路匹配和孔径匹配,较好地校正了面视场光谱成像系统中的谱线弯曲和色畸变。并且通过加入非球面反射镜及校正镜很好的校正了由于大孔径面视场所引入的非对称性离轴像差。结果表明,设计的大孔径面视场PG成像光谱仪光谱波段范围400~1 000nm,光学调制传递函数达到0.65以上,光谱分辨率达2.5nm,全谱段不同视场的谱线弯曲小于5μm,色畸变小于8μm。

Optical design of PG imaging spectrometer with large aperture and surface field

As linear field imaging by slit led to small aperture and low optical transmittance in imaging spectrometers, a large aperture imaging spectrometer based on prism-grating (PG) component was proposed.The PG imaging spectrometer employed a surface-relief type grating which can reduce the cost and fabrication difficulty of gratings.Although the large aperture imaging spectrometer had higher optical efficiency and time efficiency, the color aberrations and spectral line curvature were difficult to correct.Thereby, the telescope system was unified with the optical splitting system, which enabled the telocentric optical path mach and the aperture match with the perfect correction of spectral line curvature and color aberrations.In addition, an aspheric mirror and correction mirror were mounted to compensate the asymmetry aberration.The results demonstrate that the spectral range of the PG imaging spectrometer is 400-1000 nm, the Modulation Transfer Function(MTF) is greater than 0.65 and the spectral resolution is 2.5 nm.The spectral line curvature is less than 5 μm, and color aberrations were less than 8 μm in full spectrum.