Calibration Of System Error In Distributed Aperture Digital Holographic Imaging System

Distributed aperture synthesis imaging system based on digital holography is an advanced active imaging technique.This imaging system uses a number of sub-apertures to perform holographic detection of target scattering optical.Then,the target scattering optical complex amplitude of each sub-aperture is combined according to its spatial position,for achieving multi-aperture integrated high-resolution imaging.Considering the influence on the image quality for relative rotation magnification,displacement and tilt error between the sub-aperture,the image registration and sharpening systematic error calibration and correction method is studied.Three aspects are included;For the two errors between the sub-apertures,the calibration and correction method based on image registration was studied.Through the analysis of two errors,the calibration method based on Scale Invariant Feature was proposed.Transform algorithm and Speeded-Up Robust Features algorithm and error correction method based on image transform.The simple and the practical design basis is given.And the results show that this method has high accuracy.Compared with the SURF algorithm,the SIFT algorithm has higher accuracy under the same size speckle noise.For the displacement error and tilt error between the sub-apertures,the error correction method based on the correlation and sharpening of the image was studied.First,the error characteristics and coupling relationship between the two errors were studied;Then based on studies,image correlation and sharpening of two-stage correction method were proposed;Finally through comprehensive simulation experiments of the nine aperture,draw a conclusion that this method can effectively correct the displacement and tilt errors between sub-apertures,and improve the quality of synthetic imaging.Finally,three apertures synthetic imaging program module based on C language was designed.In the VS2013 development environment,the dialog box interface was written based on the MFC technology,and the system errors calibration and correction function was realized by using the Open CV image library and other program modules developed by ourselves.From the result of operation,it could be well applied to the actual system.