Optical Design And Stray Light Analysis Of The High Resolution Spectral Imager

Spectral imager is a new kind of remote sensing instrument which can get theinformation of spatial dimension and the spectral dimension at the same time. By thisway we can get the data cube which can be used widely in many fields. As a kind ofspectral imager, the interference spectral imager can be sorted in three types which aretemporarily modulated, spatially modulated and uniform modulated. LASIS (LargeAperture Stationary Imaging Spectrometer) is a new kind of uniform modulatedspectrometer, which has high sensitivity, good stability and strong anti-interferencecapability and so on.Research on optical design and stray light analysis of the spectral imager withhigh resolution based on LASIS are presented in this thesis. Firstly, based on itsoptical character, such as long focal length, wide spectrum, and large field of view,off-axis three mirror optical system is selected as a structure of object lens, and thenthe optical system of object lens is designed by aberration theory. Secondary,according to its character of long focal length and wide spectrum, the eyepiece withthe same structure as the Fourier transform lens is designed to achieve apochrimaticcorrection based on the formulas in which P and V were modified. Thirdly, thephysical dimension of Sagnac lateral shearing interferometer is calculated accordingto the optical system of the spectral imager with high resolution. The geometry size ofinterferometer is made by a graphics method in software Autocad. At last join theobject lens, the eyepiece, the Fourier transform lens with Sagnac shearinginterferometer together to be the whole optics of spectral imager, which has goodimaging quality. The out-of-field stray light may straight arrive at the detector without anyscattering to damage the image quality, so it should make specified stray light analysisfor the optical system. The object lens is in the form of off-axis three mirror systems,and is of emphasis of the spectrometer on the stray light analysis, so we make majorlystray light analysis for the off-axis three mirror systems. At first, the primary baffleand secondary baffle are designed by the stray light requirements and the PointSource Transmittance (PST) are given by modeling and simulating in Tracepro straylight analysis software. Based on the relationship between PST and stray lightcoefficient V, the stay light coefficient V of the system can be acquired byinterpolating PST curve. The analysis results both show that the stray light can meetthe requirement of the system.