Research On Key Technologies For Coded Aperture Imaging Spectrometer Based On DMD

Unlike the conventional opto-mechanical scan type and pushbroom scan type imaging spectrometer, coded aperture spectral imaging technology leads to luminous flux improvement by the multiplex advantage, with considerable gains in detection sensitivity and signal-to-noise ratio(SNR) of system, on the premise of hyper-spectral resolution. So the technology is one of the most significant parts in the development of imaging spectroscopy. The main research work of this paper focuses on the key technologies for coded aperture spectral imaging system based on Digital Micromirror Device(DMD), including the following aspects:(1) Spectra aliasing on DMD image plane is fully analyzed by simulation and modeling of optical system infrastructure based on Ray Tracing function. The effect of spectral line bending is studied from the simulation results, and a correcting method of 2 ?2 DMD pixels combining is proposed, with the system spectral resolution figured out after correction. Depending on the two-dimensional distribution models and hyperspectral image data source, the spectra aliasing simulation image is obtained to help enunciate the recovery from the intertwining of spatial location and spectral dispersion dimension.(2) On the basis of single mask encoding, the application of HN+/HN- masks is brought to bear for coded aperture spectral imaging system, and the formula of average Mean Squared Error for HN+/HN- masks is presented. Analysis of various aspects of system noise indicates that, HN+/HN- masks become superior to conventional encoding methods for SNR performance. A novel mask design method is proposed based on the inherent structure of DMD, which consists of bi-pattern encoding process of combining SN mask with HN+/HN- masks, and fast decoding process of sharing dedicated recovery hardware resources. Experimental results prove that the proposed design is capable of improving SNR and real-time performance.(3) The architecture of coded aperture imaging spectrometer prototype based on DMD is devised and developed, and all fabric tiles of electronics subsystem are also specifically realized. Cross-clock domain logic design, SERDES design, high speed data flow design and storage strategy issue are fully accomplished. The dynamic graphics display experiments validate the applicability of logic driver design and the feasibility of data transmission. Meanwhile the calculation results provide necessary practical evidences for the prototype to meet the requirements of real-time data acquisition and storage for massive amounts of masks data.(4) With the intent to alleviate the real-time performance bottleneck of coded aperture spectral imaging system, a novel spectra recovery processing system based on hardware acceleration technology is proposed in this paper. The system includes high speed bus interfaces design following the architecture of heterogeneous multi-processor, and acceleration algorithm design based on Fast-HadamardTransform with pipeline structure. Spectra recovery experimental results indicate that the new method can effectively exploit the potential of cutting-edge So C embedded platform, achieve high throughput and greatly enhance the system real-time performance.