Research On Terahertz Interferometric Imaging Technology

Imaging technology has become the indispensable part of modern life,which widely used in video/image recording, security detection, medicaldiagnostics, industrial control and military reconnaissance. THz imagingtechnology, was developed a new type of imaging method over the pastdecades, have attracted much attention for a lot of application in medicalimaging, non-destructive testing, security inspection, military reconnaissanceand other fields bring profound influence. Traditional THz imaging technologyusing single detector raster scanning the sample and acquire the image on apixel-by-pixel, the acquisition rate is restricted, and the imaging resolution islimited by the detection element aperture, so it can’t meet the needs of real-timeprocessing. THz interferometric imaging technique is based on the spectraldomain, by sampling information of the spectral domain of the target scene, andthen reconstructed the target image. The spatial resolution is determined bymaximum baseline in the detector array, and the image acquisition rate andresolution has potential.This paper is based on the THz interferometric imaging technology,examines the THz interferometric imaging principle, its implementation methodsand the signal interference measurements, and put forward the THzinterferometric imaging system based on the beam scanning. Then focusing onthe analysis of the detection array parameters on the imaging of performanceand imaging resolution and FOV. For the near-field THz incident wavefrontchanges, study the near-field correction methods, and combined with theMATLAB for a series of simulation experiments. The main work of the paper isas follows:Analysis of the THz interferometric imaging principles and array imagingmethods, and researched the individual detector’s electromagnetic response aswell as the relationship among the aperture weighting function, the field intensitypattern, the power pattern and the its resolution; And then analysis thecorrelative interferometer and complex correlative interferometer principle andits signal processing, finally, the real spectrum imaging and complex spectrumimaging are analyzed. The imaging resolution and FOV of THz interferometrichave studied. According to the characteristics of space application, the THzbeam scanning interferometric imaging system is raised.The detection array parameters are important factor to determine theimaging performance; Emphasis is analysis the effect of the coarray, the arrayredundancy and array factor etc. on the Imaging performance, and put forward the array design criteria. Establish the THz interferometric imaging simulationmodel, combined with the MATLAB simulated the imaging process with differentarray arrangements to point target. Experimental results show that the large fieldof high-resolution images can be obtained by rational design of the imagingarray. The near-field THz interferometric imaging is under study, and thenear-field and far-field conditions are analyzed. In order to solve the problem ofthe blurring and distortion of the reconstructive image for the near-field, andanalysis the phase correction method, and combined with the spiral arraysimulation study. The simulation results show that the phase correction caneffectively improve the quality of reconstructed image of the point source.