Study On Compressed Sensing Measurement Of Spectrum Based On Electro-optic Controlled Transmittance Coding

Spectral measurement technology is used to analyze the spectrum of light signal,and it can measure the wavelength,intensity and spectrum of emission,absorption or scattering radiation.As a basic measuring instrument,spectral measuring instrument has been widely used in the fields of industrial production,medical health and military safety,and played an important role in non-destructive testing,material analysis,environmental monitoring,geological survey,target identification,etc.With the development and application of spectral measurement technology in the fields of nanotechnology,life science,new materials and other high-tech fields,the demand for spectral measurement technology and its instrument performance continues to increase.The measurement speed,instrument volume,cost and spectral resolution of traditional spectral measurement technology are severely challenged.However,the gap must be introduced into grating spectrometer,and the contradiction between high light flux and high spectral resolution is still unsolved;Fourier transform spectrometer needs mechanical scanning,and the spectral measurement time has never exceeded the millisecond level.Therefore,it is very important to explore the spectral measurement technology with the advantages of fast,high spectral resolution,miniaturization and easy automatic control significance.Compressed sensing spectroscopy provides a new idea for miniaturization and high-speed spectroscopy,which has been widely studied by scholars at home and abroad since it was proposed.Based on the in-depth analysis of the advantages and disadvantages of grating dispersion type,interference type and other typical spectral measurement technologies,as well as the development trend of compressed sensing spectral measurement technology,this dissertation designs and develops a high-performance electro-optic modulator from the basic theory of compressed sensing to realize spectral transmittance coding;studies and analyzes the method of compressed spectral reconstruction,and develops a new instrument based on electro-optic controlled transmission coding.In order to obtain a high-speed,high-precision,high-resolution and miniaturized compressed sensing spectral measurement technology,a new compressed sensing spectral measurement theory and method is explored.The main research work and achievements in the dissertation are as follows:1.A theoretical model of compressed sensing spectrum measurement based on electro-optic controlled transmittance coding is established.Starting from the basic theory of compressed sensing,this dissertation discusses three basic problems in the theoretical framework of compressed sensing:signal sparseness,sensing matrix design and signal reconstruction algorithm in detail;compares and analyzes the basic principles and methods of the existing compressed sensing spectral measurement,and proposes a compressed sensing spectral measurement based on the electro-optic transmittance control coding in view of the shortcomings of the existing compressed sensing spectral measurement scheme,the basic principle of the scheme is discussed in detail,and the theoretical model of compressed sensing spectral measurement based on the electro-optic controlled transmission coding is established.The theoretical research shows that the electro-optic modulation technology can directly realize the compressed sensing coding in the spectral dimension,which provides theoretical support for the theoretical,simulation and experimental research of this dissertation.2.The scheme of electro-optic modulator is designed,and the dispersion characteristics of its wide spectrum application are studied.Starting from the basic principle of electro-optic effect,the transverse electro-optic effect of LiNbO₃ crystal is analyzed,and the mathematical model of the relationship between the refractive index difference and the external electric field is derived under the different cutting modes of the electro-optic crystal.On this basis,the x-cut LiNbO₃ is selected as the crystal material of the electro-optic modulator,and the feasibility of the design scheme of the electro-optic transmittance modulator of LiNbO₃ is analyzed.In order to achieve the precise regulation of the electro-optical transmittance,the electro-optic coefficients of lithium niobate materials are precisely calibrated,and the electro-optical coefficients of multiwavelength incident light are measured and studied,the spectral dispersion characteristics of the electro-optical coefficients are analyzed,and the precise calibration of the wide spectral electro-optical coefficients is realized,which provides the basis for the application of the spectral transmittance coding.3.The sensing matrix design and spectral reconstruction algorithm of spectral transmittance coding are studied.Based on the selection of spectral signal sparse method and the pseudo-random measurement characteristics of maximum uncorrelated measurement,a sequential floating forward selection method is proposed to design the spectral transmittance coding sensing matrix.Based on the completion of signal sparse and sensing matrix design,the performance of spectral reconstruction of orthogonal matching pursuit algorithm and Sparsity adaptive matching pursuit algorithm is compared and analyzed by simulation.Based on the quantitative analysis of compression ratio,relative error of reconstructed spectral signal and reconstruction time,the transmission coding matrix and spectral reconstruction algorithm are established,The simulation results show the feasibility of the theory and scheme of the compressed sensing spectrum measurement,and provide guidance for the design of the compressed spectrum measurement system.4.The compressed sensing spectrum measurement system is built,and the spectrum measurement experiment is carried out.From the two aspects of optical system design and hardware circuit design,the optical system design and component selection of the spectral system are completed,and the optical system of spectral measurement is built;the electrical performance of the electro-optical modulator is analyzed,and the driving control system of the electro-optical modulator with AC high voltage is designed;according to the requirements of driving voltage real-time calibration and compression of spectral data measurement,a two-way data acquisition system is designed based on FPGA,the compressed spectrum measurement system is built to realize the synchronous acquisition of the driving voltage signal and the spectrum measurement signal.Finally,the spectrum measurement experiments on LED,laser and fluorescent light source are carried out by using the spectrum measurement system designed in this dissertation.The experimental results show that the spectrum measurement system has realized the hyperspectral resolution,high speed and high precision compressed sensing spectroscopy.The research in this dissertation will contribute to the development of compressed sensing spectral measurement technology,and will enrich the theory and method of spectral measurement.