Edge Enhancement Of Incoherent Digital Holographic Images Based On Spiral Phase Mask Modulation

The digital holography of incoherent light illumination based on the spatial light modulator has great advantages.It does not need the illumination of coherent light source in the imaging process,and does not need to move the test device and the scanning device.The incoherent digital holography system has a simple structure,no strict experimental environment and more flexible holographic image reconstruction,so it is of great research value and practical value compared to the traditional optical holography system.Based on the study of incoherent digital holography system,this paper mainly studies the application of the system in the field of holographic image edge enhancement.Based on the wave optics theory,the system point spread function based on two lens phase and the point spread function based on spiral phase are deduced respectively.The principle of system recording and reproduction is analyzed,and the factors that affect the imaging resolution of the system are discussed.The MATLAB software is used to simulate the three-dimensional imaging characteristics and the spiral point expansion function respectively,and the experimental results are consistent with the simulation results in the experiment.The incoherent digital holography system is built to verify the imaging characteristics of the system on the amplitude object and the phase object under the two phase mask modulation of the dual lens phase and the spiral phase.The main contents of this paper include the following four aspects:(1)Firstly,the development of digital holography and incoherent digital holography is introduced respectively;then the image edge enhancement technology and its development process are introduced;finally,the research focus and main contents of this paper are introduced.(2)Secondly,based on the Fresnel diffraction theory,the point spread function of the incoherent digital holography system based on the phase of the double lens is derived,and the mathematical expressions of the system hologram,the transverse magnification and the reappearance distance are given respectively.This paper introduces the three step phase shift technique of eliminating the zero order image and the conjugate image in the reproducing process of the coaxial hologram,introduces the angular spectrum diffraction algorithm of the holographic reproduction,and analyses the causes of the imaging resolution affecting the system.(3)Thirdly,the three-dimensional imaging characteristics of the incoherent digital holography system are simulated when the spatial light modulator is loaded with two lens phase mask.A incoherent light illuminated digital holography system was built,and high quality reappearance images were obtained from the imaging experiments of the resolution plate.The holographic images of the amplitude objects(steel scales,coins)and phase objects(dyed and non dyed onion epidermal cells)were hologram and high quality holographic reproduction images were obtained.(4)At last,from the angle of wave motion optics,the expression of spiral point diffusion function of incoherent digital holographic imaging system based on spiral phase is deduced.The impulse response of the system is verified experimentally.The conclusion is consistent with the simulation results of point diffusion function,which proves the correctness of the expression of point diffusion function.The three-dimensional imaging characteristics of the spatial light modulator when loading the spiral phase mask are verified.The amplitude objects(steel feet,coins)and phase objects(dyed and non dyed onion epidermal cells)were hologram,and high quality holographic reappearance images were obtained,and the contrast enhancement of the edges was achieved to a certain extent.