Research On The Optical System Of Broadband Plane-grating Imaging Spectrometer

Imaging spectrometer, which has both the function of traditional spectrometer toobtain spectral information and traditional imaging instrument to obtain target information,is a new kind of space optical remote sensing instrument combining imaging techniquewith spectrum technique. In order to propose an ideal optical structure for thecorresponding fabrication of the broadband plane-grating imaging spectrometer, theapplication requirements, systematic classification, structural characterization, aberrationtheory and design methods of the imaging spectrometer is studied in this dissertation.A theory which acting grating as the division point, system astigmatism can becorrected by correcting the astigmatism of pre-optical path and post-optical pathrespectively is proposed on the base of introducing basic theory of imaging spectrometer. ACzerny-Turner imaging spectrometer is constructed based on the designing thought, namedimaging spectrometer based on double cylindrical mirrors system. In order to satisfy therequirements of spatial resolution and spectral resolution, a deep analysis of the aberrationtheory for imaging spectrometer is made before optical simulation is done. Thenastigmatism corrected conditions and wide band imaging conditions are deduced anddiscussed corresponding to the optical structure. Finally, the final broadband imagingspectrometer system is designed and the optical structures can satisfy the designrequirements.The spectral range for broadband plane-grating imaging spectrometer is200-700nm.Imaging spectrometer based on double cylindrical mirrors system, the spectrometer systemapplies double cylindrical mirrors system in both the collimating optics and focusing optics,contains only cylindrical mirrors and plane grating, is easy in fabrication and alignment.However, due to more reflective surfaces, the energy utilization ratio is less. The spectralresolution of the imaging spectrometer is less than3nm, MTF for all field of view is largerthan0.4at25lp/mm at each wavelength.An distortion-corrected method for astigmatism-corrected Czerny-Turner imagingspectrometer is proposed. The magnification difference of spectral dimension and spatialdimension of the image when the grating are in level0and level1and the influence ofimage magnification of different wavelength are analyzed, and the correction formula,methods of distortion correction and common characteristics based on cylindrical mirrorand toroidal mirror imaging spectrometer are given，too. The validity of correction formulaof distortion is verified with theoretical calculation, ray tracing simulation and experimental measurements with the imaging spectrometers. Meanwhile, this method is useful to thedistortion correction of off-axis dispersion imaging spectrometer in other operatingconditions of collimated light.