Optical design of an Offner coded aperture snapshot spectral imaging system based on dual-DMDs in the mid-wave infrared band

Abstract

With the advantages of flexible encoding and high frame rate, the digital micromirror devices (DMD) have been used as a binary encoding mask in the coded aperture snapshot spectral imaging (CASSI) systems. But the use of DMD will cause the image plane to tilt at a specific angle, so it is almost impossible to realize the strict matching between the optical system of CASSI and the cold stop of the infrared focal plane array in the mid-wave infrared band. In this paper, a CASSI system with two DMDs based on the Offner spectrometer is proposed to solve the above problem. The concept and working principle are described in detail. Under the premise of the matching optical parameters, the telescopic system, Offner spectroscopic system and microscopic system are designed independently. Then the integrated optimization design method is adopted, and the aberration of the microscopic system is used to offset the astigmatic aberration of the Offner spectroscopic system, and the imaging quality of the system is improved. The results of performance measurements confirm that the system has desirable spatial resolution and spectral response functions. Thus, the concept and optical design of the proposed system are verified to be effective and valuable.