Optical System Design Of Gratings-based Imaging Spetrometer

The imaging spectrometer technique is an optical remote sensing instruments which is developped on the basis of multi-spectral remote sensing technology to obtain the object of two-dimensional spatial information and one-dimensional spectral information. such multidimensional imaging instruments have broad application prospects, important value, and strategic significance in the disciplines of atmospheric science, geology, astronomy,ecology, biomedical,cosmic exploration.The grating-based imaging spectrometer is composed of the fore optics system and spectral imaging system. It's principle is simple, performance is stable, the technology developped and achieved well results, occupy the main position of practical imaging spectrometer technology. The research direction in this paper is optical system design of grating-based imaging spectrometer study. It does the following works:First, on the basis of the application requirements of imaging spectrometer and sum up the situation and development trend of domestic and international,the research content is cleared. Second, the theory of a grating-based imaging spectrometer are explained, which provide a theoretical basis for the grating-based imaging spectrometer system design. Then, in spectral imaging system design, according to the instrument requirements determine the technical parameters of the spectral imaging system. The spectral imaging system is designed using the Czerny-Turner configuration and a spectral imaging system composed of a convex grating respectively. Against the problem of aberration correction limited and imaging quality is poor of the traditional Czerny-Turner configuration, using a convex grating-based configuration. The results show that the based on the convex grating spectral imaging system aberration is well corrected, compact, ideal for imaging quality to fully meet the specifications of spectral imaging system.Next, based on the principle that the fore optics system should match with the spectral imaging system to determine the technical parameters of the fore optics. Choosing refractive cassegrain structure as the initial structure. In order to further improve image quality, reduce processing difficulty and cost, the fore optic system uses a improved cassegrain system.The results indicate that the image quality is better, the process and adjustment is easily. Finally, after spectral imaging system splicing to the fore optics system, adjust the whole system to complete the optical design. The analysis and assignment of its tolerance show that this optical design completely and feasible meet the application requirements of the grating-based imaging spectrometer.Grating-based imaging spectrometer the RMS radius of SPT is less than 2.87um, the 80% of the imaging energy is concentrated in the 7.5um,the MTF of both the center and the edge wavelength is higer than 0.6 at the characteristic frequency 331p/mm, the imaging quality of optical system is close to the diffraction limit. This optical system design achieves a wide-band aberration correction, also obtains a well imaging quality. The optical length is 336mm.