Research On Large-area Single Photon Compressive Imaging System

Drawing on the idea of high-flux measurements of Compressed Sensing(CS),single pixel imaging technology keeps the noise in the single-pixel level.So that the signal-to-noise ratio is greatly improved.In particular,the combination of this technology and photon counting technology in extremely weak light detection can highlight and amplify the above advantages.The imaging method combining single-pixel imaging with photon counting technology is called "single photon compressive imaging" in this paper.Due to the advantages of super-sensitivity,low measurement dimensions and sub-sampling,single photon compressive imaging has broad applications prospects in the fields of astronomical observation,fluorescence microscopy and medical detection.Since the large memory consumption and computational complexity of large-area image reconstruction,the imaging area of the single-photon compressive imaging is very small at present.Moreover,most of the existing imaging area expansion schemes are at the expense of sampling time,which seriously affects the real-time performance of imaging systems.In this context,this paper will focus on the research on large-area single photon compressive imaging,and the main research contents and results are as follows:(1)A large-area single photon compressive imaging system with the full screen of DMD as imaging area is developed,and a self-designed parallel light source and a photon-counting Photomultiplier Tube(PMT)with a large photosensitive area are adopted.According to the functional requirements of the imaging system,a control and counting circuit,based on Field-Programmable Gate Array(FPGA),is developed.(2)The model of single photon compression sampling is established.And then Monte Carlo method is used to simulate single photon compressive imaging system.Three kinds of binary matrix are constructed.The influence of measurement matrix type,sparsity and the number of measurements on the imaging performance of the system are studied by Monte Carlo simulation.In addition,the Monte Carlo simulation of dual DMD compressive spectral imaging is implemented,which lays the theoretical foundation for follow-up work.(3)To shorten the sampling time,reduce memory occupation and computational complexity of large-area imaging,a large-area imaging scheme based on multi-micromirror combination modulation is proposed.The signal-to-noise ratio and detection limit of the imaging system is theoretically deduced.Theoretical analysis and experimental results show that multi-micromirror combination imaging method is more suitable for faster imaging in a weaker light level environment.In order to achieve high imaging quality,the size of the combined pixels and the average time of each measurement should be moderate,so that the impact of Poisson shot noise is minimized.(4)Based on the large-area single photon compressive imaging system,a time-adaptive sampling method is proposed.The theory of threshold of light intensity estimation accuracy is deduced,and based on it,a FPGA-based sampling control module is developed.Finally,the advantage of the time-adaptive sampling method is proved experimentally.Imaging performance experiments show that,the time-adaptive sampling method can automatically adjust the sampling time for the change of light intensity of image object to obtain an image with better quality,and avoid speculative selection of sampling time.