Research On Passive Ranging And3d Imaging Technology Based On Aperture Coding

Three-dimensional imaging technology has been widely used in various fields.In the process of acquiring three-dimensional information of military targets,the system is required to have high concealment,simple structure,small size and suitable for long-distance.However,the traditional active or the passive three-dimensional imaging method cannot meet the above conditions at the same time.Therefore,combined with computational imaging technology,this paper uses the chiral phase mask aperture coding to study the monocular passive ranging system with small size and remote measurement.The aperture coding technology adds a phase mask to the pupil of the system,so that the intermediate coded image changes with the object distance,and the depth information is extracted from the encoded image.The main research contents of this paper include:(1)Theoretical study on aperture coded passive ranging and three-dimentional imaging technology.Based on the coding and decoding theory,the principle of passive ranging and 3D imaging based on chiral phase mask is analyzed in detail.(2)In order to gain a deeper understanding of system performance and facilitate system design under different technical requirements,the imaging characteristics of the aperture coding system are analyzed.In the analysis of frequency and space domains,explicit mathematical expression of OTF and PSF with defocus are given.The influence of system and phase mask parameters on ranging accuracy and range under different conditions is simulated and analyzed.The available accuracy increases with the increase of phase mask width and interval,the increase of focal length,and the decrease of pixel size.(3)Phase mask optimization and ranging algorithm research.This paper uses Fisher information theory to optimize the design of the chiral phase mask.When the normalized pupil coordinate makes the aperture size 2,the phase mask width is about 0.7.Aiming at the problem that the second peak of the auto-correlation pattern is not obvious,combining Laplace filtering and the wavelet denoising method to process the encoded image can effectively improve the signal-to-noise ratio and make the second peak obvious.(4)Experimental verification and analysis.This paper builds two sets of aperture coding systems for experiments with different distance targets.The measurement error in the target experiment at a close range of 1m is 0.7%.Compared with the unoptimized system,the phase mask optimization design method in this paper can reduce the system volume by about 55% under the same accuracy.In the long range target experiment,the overall measurement result is close to the actual object distance range,and the three-dimensional imaging result can reflect the change of the target depth,and the experimental effect is good..