Abstract
We have developed a single photon compressive imaging system based on single photon counting technology and compressed sensing theory, using a photomultiplier tube (PMT) photon counting head as the bucket detector. This system can realize ultra-weak light imaging with the imaging area up to the entire digital micromirror device (DMD) working region. The measurement matrix in this system is required to be binary due to the two working states of the micromirror corresponding to two controlled elements. And it has a great impact on the performance of the imaging system, because it involves modulation of the optical signal and image reconstruction. Three kinds of binary matrix including sparse binary random matrix, m sequence matrix and true random number matrix are constructed. The properties of these matrices are analyzed theoretically with the uncertainty principle. The parameters of measurement matrix including sparsity ratio, compressive sampling ratio and reconstruction time are verified in the experimental system. The experimental results show that, the increase of sparsity ratio and compressive sampling ratio can improve the reconstruction quality. However, when the increase is up to a certain value, the reconstruction quality tends to be saturated. Compared to the other two types of measurement matrices, the m sequence matrix has better performance in image reconstruction.
Highlights
Photon counting imaging is a method of imaging at very low light levels based on photon counting technology, which has broad application prospects in the field of ultra-weak light detection, such as biomedical detection [1,2,3,4], deep space exploration [5], and spectral measurement [6,7].At present, the detectors with single photon counting capability like photoelectric multiplier, avalanche photodiode and superconducting single-photon detector, all belong to single-pixel detector
The image is randomly modulated by a digital micromirror device (DMD), and the two-dimensional image is reconstructed with the optical signal received by a single-pixel detector each time and the pseudo-random code loaded into DMD
A DMD control and photon counting logic based on FPGA is specially developed and several mirrors are combined together as onewith pixel to reduce sampling and reconstruction time
Summary
Photon counting imaging is a method of imaging at very low light levels based on photon counting technology, which has broad application prospects in the field of ultra-weak light detection, such as biomedical detection [1,2,3,4], deep space exploration [5], and spectral measurement [6,7]. With the introduction of compressed sensing theory, a new imaging method called single-pixel imaging appeared in 2008 [22,23,24]. In this scheme, the image is randomly modulated by a DMD, and the two-dimensional image is reconstructed with the optical signal received by a single-pixel detector each time and the pseudo-random code loaded into DMD. Higher sensitivity than photon counting imaging based on the single photon detector array is verified experimentally [28] This method, which uses the advantages of high flux and sub-sampling of compressive imaging and high sensitivity of photon counting to achieve ultra-sensitive imaging, is called single photon compressive imaging. The performance of the single photon compressive imaging system under different measurement matrices is evaluated
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