The Research Of Photon-counting Spectral Measurement Based On Compressed Sensing

Spectrometer is one of the most important analytical instrument in the ?eld of industrial production and scienti?c research. With the development of science and technology, the application ?eld of the spectrometer expand. More and more non-conventional spectral measurement needs related to weak light and infrared become popular. The technology of weak light spectrum measurement has important applications in astronomy, ?uorescence, Raman and many other ?elds,such as high sensitivity spectroscopy equipment can be used to observe the fainter objects in the universe. Among the applications of infrared spectroscopy measurements, the most noteworthy one is the application values in the military, and it is especially suitable for the complex environment of night vision, smoke and under water in modern war, and so on. The conventional spectrum measurement of visible light uses the linear array charge-coupled device(CCD) detector, but this method is not suitable for low light and infrared spectroscopy. The detector manufacturing technology for low light and infrared spectroscopy is not mature and a small number of products are very expensive. If the linear array spectral measurement method is used, no satisfactory performance can meet in sensitivity, resolution and cost. Therefore, seeking a new method for the weak light and infrared spectroscopic measurements will be of great scienti?c signi?cance and application values.In order to meet the high sensitivity and high resolution in weak light and infrared spectroscopic measurements, a single pixel spectral measurement method based on the compressed sensing(CS) theory is presented in this thesis. In thismethod, the single pixel photomultiplier tube(PMT) detector of single photon counting is used for optical signal detection. The spectral bands are obtained through compressed modulation and reconstruction. Compared with the previous similar products of spectrometer, this method can improve the detection sensitivity and spectral resolution signi?cantly.The main research contents of this thesis are as follows:(1) The spectral measurement mode based on linear array CCD and the scan spectrum measurement mode based on PMT were compared with experiments.The advantage of sensitivity of the PMT detector with single photon counting is demonstrated under the condition of the weak light, and the obvious improvement of spectral resolution is also obtained.(2) We investigate the compressed sensing theory. The compressed sensing applications involved design matrix, algorithm selection and signal sparsity is studied by numerical simulation for compressed sensing spectrum measurement requirements. Using a local Hadamard matrix extracted from the Hadamard matrix as the measurement matrix better quality of reconstructed spectral can be obtained compared to the pseudo random matrix. In addition, the sampling rate and the e?ect of noise level on the quality of spectral reconstruction are also examined. Finally, it is demonstrated that the single pixel spectrometer not only has the advantage of sub sampling but also has better signal to noise ratio characteristics comparing with scanning spectrometer and Hadamar transform spectrometer.(3) An experiment system of single pixel spectrometer is built based on compressed sensing theory. According to the characteristics of linear optical element, a complementary measurement techniques of compressed spectral is proposed. With the method of complementary measurement, the spectral re-construction quality can be improved greatly compared with the previous non negative way and mean subtraction method. Finally, we came to the conclusion that the sampling rate of 30% is appropriate for complementary measurement method. Besides, the advantage of local Hadamard measurement matrix is also demonstrated further in the compressed sensing spectral measurements through experiment with respect to pseudo random matrices.(4) The practical aspects of the research were carried out with single pixel spectrometer. A re?ective single pixel spectrometer experiment system is built,and spectral resolution of the system is measured. The position and amplitude of the spectrometer are calibrated with the standard light source. Finally the absorption spectra of colored samples are measured with single pixel spectrometer experimental system and the auxiliary measuring equipment was designed.The proposed architecture of single pixel spectra measurement can meet the requirement of weak light and infrared applications of high sensitivity, high resolution spectroscopy. It also has advantages of sub sampling, good robustness and low complexity. It is bene?cial to the miniaturization and portability of spectroscopy equipment and convenient for popularization and application.