Research On Pivotal Technique Of Fourier Single Pixel Imaging In Spatial-Time Domain

A new type of imaging technology-correlated imaging technology has received extensive attention from many researchers at home and abroad in recent years.Different from the traditional imaging technology using area array detectors,this technology uses single-pixel detectors combined with optical modulation devices and related algorithms to achieve imaging of target objects.Therefore,the correlated imaging technology is often referred to as single-pixel imaging technology.Single-pixel detectors have a larger spectral selection range than traditional area array detectors.Therefore,the correlated imaging technology has potential imaging advantages and huge application value in the band where area array detectors cannot image or are expensive.At the same time,single-pixel imaging detects the total energy of the reflected or transmitted light of the object,so it also has a huge prospect in the field of low light.However,the development of single-pixel imaging technology still has a certain gap with traditional area array imaging in terms of several important performance indicators,such as imaging quality and imaging efficiency.Regarding how to improve the performance indicators of single-pixel imaging technology,domestic and foreign scientific researchers have carried out a lot of research work,and have also achieved fruitful scientific research results.This dissertation continues on the basis of previous researches.This dissertation mainly focuses on sparse Fourier single-pixel imaging technology and time-domain Fourier single-pixel imaging technology to carry out research work.In view of the shortcomings of the existing related technologies,new research solutions are proposed,theoretical analysis is provided,and corresponding computer numerical simulation and experimental verification work are carried out.The main work of this paper is summarized as follows:(1)In order to improve imaging efficiency,traditional Fourier single-pixel imaging usually selects only low-frequency information and discards high-frequency information to reduce the number of samples acquired.This method of sampling only a small amount of low-frequency information will result in the loss of the detailed information of the final imaged object and reduce the imaging resolution.In addition,due to the frequency truncation,the ringing effect of the restored image is obvious.In response to this problem,this paper proposes a variable-density sparse Fourier single-pixel imaging technology,which can reduce the number of sampling and at the same time ensure high image restoration quality.The proposed method utilizes the characteristics of Fourier spectrum distribution,that is,the power of image information gradually decreases from low frequency to high frequency in Fourier space.The variable density random sampling matrix is used to randomly sample the spectrum information,and then the compressed sensing algorithm is used to invert the information,and finally a high-quality restored image is obtained.Compared with the Fourier single-pixel imaging method that only obtains low-frequency information,this method can effectively improve the quality of image restoration.In addition,considering that the resolution of the system is limited by diffraction,this method can also achieve high-resolution imaging.(2)Time-domain single-pixel imaging technology can use a low-bandwidth detector to obtain fast-changing time-varying signals.However,we can only obtain information about the change of signal amplitude over time from the time-domain information of time-varying signals,and cannot directly obtain the frequency characteristics of time-varying signals,such as the frequency composition of time-varying signals and the size of each frequency component.However,spectrum analysis can solve this problem very effectively.In the field of signal processing,the use of Fourier transform to obtain the spectrum distribution has become an important method widely used.According to the spectral characteristics of time-varying signals,only important frequency information can be detected,and unimportant frequency information can be discarded,which can improve the sampling efficiency of the system while retaining most useful information.In this paper,combining the characteristics of time-domain single-pixel imaging and Fourier transform,a Fourier time-domain single-pixel imaging method for directly obtaining time-domain information spectrum is proposed,and a research system is built,using a certain sine and cosine distribution The time-varying light intensity directly obtains the frequency spectrum information of the time-varying signal according to the signal intensity.This method can detect and obtain the characteristic information of the time-varying signal from the signal very flexibly.The spectrum distribution information obtained by this method can be easily analyzed and processed in the time domain,and the time domain amplitude information can also be obtained through inverse Fourier transform processing.Fourier time-domain single-pixel imaging combines the advantages of both time-domain single-pixel imaging and Fourier spectrum analysis.It has important value and applications in the field of weak and instantaneous signal acquisition and analysis.It also has the ability to use low-bandwidth detectors to obtain fast time The ability to change signals.