Optical Design Of The Coded Aperture Spectral Imager Based On A Digital Micromirror Device

Coded aperture spectral imager has received tremendous attention in spectrometry owing to its high luminous flux,high signal-to-noise ratio,and flexible encoding method.As an ideal element for coded aperture devices,the flexibly encoded digital micromirror device(DMD)provides new techniques for the development of coded aperture spectral imager,while also brings new challenges to the design of optical system.The use of the DMD would reduce the optical system performance and increase its design difficulty.Over the past several years,numerous studies have been reported on the DMD-based coded aperture spectral imager by scholars in various fields.However,most of these studies focused on the fact that the encoding template,encoding mixing,coding matrix optimization design,and image restoration,while studies of optical systems are rarely reported,and the effects of the DMD on optical systems have not been studied.Based on the requirements of high performance and system engineering of coded aperture spectral imager,and the blank of the research on the effect of the DMD on optical system,the following research is carried out in this paper:1)The coded aperture spectral imaging system of two structural forms is studied.Based on the characteristics of the structural form and coding method,the working principle and spectral resolution of the DMD-based coded aperture spectral imager optical system are analyzed.2)Based on the causes of aberrations caused by the DMD in the converging optical path and the imaging characteristics of the DMD in the converging optical path,the effect of the DMD on the coded aperture spectral imaging optical system is analyzed theoretically,corresponding solutions are proposed to mitigate the effect and guide the optical system design.3)According to the technical index of the optical system,the optical components are reasonably selected,the parameters of each subsystem are determined,and the optical system design,image quality evaluation and tolerance analysis are performed.Finally,the DMDbased coded aperture spectral imaging optical system with a spectral range of 700nm-1000 nm,a maximum spectral resolution of 0.5nm,good imaging quality,and loose system tolerances was realized.