The Aperture Synthesis Algorithm And Experimental Research Of Generalized Phase-Shifting Digital Hologram

Digital holography has been widely applied in various field of science research, Biomedi-cal and engineering. However, The resolution of recording devices CCD which used in the system of digital holography lower than traditional holography recording devices 1-2 order of magnitude. Though it can separate the zero order items and conjugate image but the angle between reference wave and object wave is very small when use off-axis record, and this limited the practical application of digital holography.In 1997, Phase-shifting Interferometry was proposed by Yamaguchi and phase-shifting technique was introduced into digital holography and solve the contradiction. This technique is depend on the accuracy of phase-shifting devices heavily. Generalized phase-shifting interferometry was proposed. It can reduce the reliance on the accuracy of phase-shifting devices for the phase shift can be arbitrary and can even unknown. The researchers is no longer satisfied with the reconstructive image’s quality of object wave and hope can enlarge the recording area with the deepening study. How to improve the resolution of holographic system and enlarge the recording area for collecting more information has attracted many researchers’ attention. The recording size on the CCD chip is very small which is generally about 1-4, but the size of pixel is so big which is generally about 6-102cmμm.It is so difficult to record the high frequency information of object wave that limited the resolution of the experiment system. People hope to enlarge the size of CCD chip and narrow down the size of pixel. But it is difficult to processing CCD which has larger size of chip, and the cost is very high. It can reduce the signal to noise ratio if we narrow down the size of pixel, and it hard to avoid mutual interference because the distance between pixels is very close. If only consider about CCD, it is hard to improve the reconstructive image’s quality of objective wave.In this letter, we present a method to realize aperture synthesis in generalized phase shift digital holography which based on the distribution of object wave intensity. It not only improved the resolution of holography system and the reconstructive image’s quality of object wave. The optical experiment results showed that the present method is effective. Further we considered the phase distributed affection to the reconstruction of the original object wavefront and the shortcoming improvement of this method. The optical experiments results also showed that the improved method was effective. In addition, An advanced phase-shifting interferometry approach with a spherical wavefront reference is proposed to improve the quality of the holographic image. Computer simulations and optical experiments show the feasibility and effectiveness of this method.