Research On Dual Wavelength Digital Phase Shift Holographic Background Free Phase Retrieval Technology

Dual wavelength digital holography technology is an imaging technique that can be used for three-dimensional morphology detection,with the advantages of non-contact,high accuracy,and no damage.Among them,dual wavelength off axis digital holography technology can achieve non exposure imaging measurement of objects with sharp edges in large depth through a single exposure acquisition,which has attracted widespread attention in recent years.However,in order to achieve phase retrieval,existing dual wavelength off axis digital holography often requires the use of background holograms without samples to eliminate the influence of carrier phase.In practical engineering,background holograms are often difficult to obtain,resulting in poor or even impossible phase retrieval quality.Therefore,how to use a dual wavelength off axis digital hologram with samples to achieve accurate and high-quality phase retrieval has significant academic research value and engineering application significance.The research purpose of this paper,"Research on Phase Retrieval Technology of Dual Wavelength Digital Phase Shifting Holography Without Background",is to use techniques such as spatial carrier phase shifting and linear regression to achieve high-quality retrieval of dual wavelength off axis digital holography without background holograms,while effectively suppressing the influence of carrier on phase retrieval.The main research content of this paper is as follows:On the basis of analyzing the existing dual wavelength off axis digital holographic phase retrieval techniques,and considering the carrier residue problem in commonly used algorithms and the need for additional processing with sample free holograms,a phase retrieval technique based on spatial carrier phase shift was studied.This technology applies spatial carrier phase shifting technology to obtain multiple holograms containing different phase shifting components in the case of only one dual wavelength off axis digital hologram.By utilizing the difference between the phase shifting components in each hologram,the estimated carrier component is obtained(with an estimation error of 10-5 rad/pixel),and the hologram is processed using this estimation value to suppress the impact of carrier information on phase retrieval.In order to further improve the resolution of phase retrieval,based on the analysis of phase retrieval technology based on spatial carrier phase shift,a spatial carrier phase shift phase retrieval technology combined with linear regression was studied.This technology obtains multiple holograms containing different phase shift components by applying spatial carrier phase shift technology,and completes carrier estimation using phase retrieval technology based on spatial carrier phase shift.Subsequently,the carrier information and phase information were separated from each other through least squares iteration and linear regression techniques,and the impact of the carrier on them was suppressed during the phase retrieval process.In this technology,phase retrieval operations can be completed without the need for sample free holograms,achieving highresolution phase results at the expense of time.