Near-Infrared Correlation Imaging And Spectral Imaging Based On A Single-Pixel Detector

Different from traditional optical imaging,ghost imaging(GI)is an indirect imaging method that uses light field intensity fluctuations to restore images.It has the characteristics of anti-turbulent media interference and can achieve super-resolution.In the traditional GI experiments,two detectors are used to detect the light field distribution on the surface of the object and the total light intensity after the light field interacts with the object.The information obtained by the two detectors is subjected to a second-order correlation operation to recover the object information.Because the detector that detects the interaction between the light field and the object is a single-pixel detector or so-called bucket detector(BF),it has no spatial resolution capability.At the same time,the two individual detectors do not contain the two-dimensional information of the object but the object information can be recovered after the correlation,hence the name ghost imaging.In this paper,an experimental demonstration of GI of a binary object is carried out on the basis of dual-channel correlation imaging with a near-infrared continuous wave 1064 nm laser as the light source and a digital micromirror device(DMD)as the modulator.Through both simulation and experiment,it is shown that the use of a Hadamard matrix can realize the image reconstruction with a much lower sampling rate than with a random matrix of the same resolution.At the same time,an increase in the number of samples will increase the signal-to-noise ratio,though the sampling and reconstruction time will also be increased.Due to the orthogonality and completeness of the Hadamard matrix,the clearest image of the object can only be recovered when full sampling is performed.In our experiment we used a 32 ? 32 Hadamard matrix as the modulation matrix,and then performed threshold filtering on the reconstructed image.By analyzing the filtered results,it was seen that the noise in the low-frequency part will affect the imaging quality.Therefore,using high-pass filtering to filter out low-frequency noise gives the best imaging quality.In addition,a combination of spectral imaging and second-order GI was also carried out.The spectrum can provide information about the surface and part of the internal properties of the object.As an imaging method that integrates the spectrum,spectral imaging can be combined with GI to achieve non-localized spectral ghost imaging.Through spectral correlation imaging,the two-dimensional features of the object can be obtained while obtaining spectral information.Through comparison of specific spectral characteristics,terrestrial observation can be performed,and a wide range of applications in the marine,military,and agricultural fields are possible.Through preliminary experimental design,a computational spectral imaging experiment based on a 1064 nm laser light source,a grating-type fiber spectrometer as a detector,and a DMD as a modulation device has been built.The experimental optical path adopts a single-pixel imaging scheme,and the possibility of spectral ghost imaging has been preliminarily verified.In the future,through the combination of near-infrared and visible light spectral ghost imaging,full-spectrum all-weather computational spectral imaging can be realized,laying the foundation for its development in remote sensing,aerospace and other fields.