方形孔径棱镜式成像光谱仪光学设计

Prism Hyperspectral Imaging Optical System Design with Rectangular Aperture

为满足星载高光谱成像的需要,通过分析实际星载成像光谱仪应用需求,确定了光学设计的指标。设计中,使用方形孔径代替圆形孔径,采用双胶合棱镜和单棱镜作为分光元件分别设计可见近红外(VNIR)和短波红外(SWIR)光谱仪,并利用远心离轴三反结构设计望远物镜;分析了双胶合棱镜校正色散非线性的原理,利用光学软件Zemax分别设计了望远物镜和光谱仪系统,并采用沿轨方向视场分离的方法实现了SWIR和VNIR的分别成像。对光学系统的整体分析结果表明,该系统能够满足光谱分辨率和地面分辨率指标的要求,方形尺寸不仅可减小成像光谱仪的纵向尺寸,更有助于对像差的校正,利于实际工程应用。对VNIR波段色散结果的分析表明胶合棱镜能够很好地校正棱镜色散非线性。

In order to meet the needs of space-borne hyper-spectral imaging, the parameters of optical system are determined based on analyzing application requirements. Rectangular aperture is used, instead of circle aperture, and doublet prism and single prism are used as dispersion elements to design visible near-infrared （VNIR） and short-wave infrared （SWIR） spectrometer respectively. Telecentric three-mirror anastigmat （TMA） is adopted to design the telescope objective. Principle of cemented prisms used to compensate the nonlinear dispersion of single prism is discussed. TMA and spectrometers are designed with Zemax optical software, and the field splitter along the track direction is used to achieve imaging of VNIR and SWIR respectively. According to the overall analysis, the optical system meets the indicators of spectral resolution and ground resolution. Using the rectangular aperture not only can reduce the size in longitudinal dimension, but also is helpful to the aberration correction, which is conducive to the practical application of engineering. The VNIR band dispersion result shows that doublet prism is a useful method to correct the nonlinear dispersion of prism.