The 3D Reconstruction Of Digital Holography By Method Of Phase-shifting

Digital holography is a mix of optical holography, computer technology and electronic imaging technology. Based on the theory of optical holography, digital holography utilizes CCD array which is used for the recording medium to record holograms and fulfills the numerical reconstruction of the original object by computer which implements full numerical recording, storing and reconstructing process in real time. Digital holography can obtain phase and amplitude of the object at the same time which is a big advantage compared to other techniques. So it has many applications in optical measurement,image recognition and encryption,microscopy and so on.Introducing phase-shifting technology to digital holography can reconstruct original object image directly. It removes the influence of the conjugated image and zero-order diffracted image, increases the pixel numbers of the reconstructed image, and improves the quality of the reconstructed image. So it has more applications in many fields.This paper is concentrated on the theoretical and experimental studies on the phase-shifting digital holography. The main tasks are as follows:(1) Firstly the holography are summarized, then the history,development and application of digital holography are expounded. The principle of digital holography is introduced, and in-line step is compared with off-line setup in detail.(2) Secondly, The development and the main applications of phase-shifting digital holography are summarized. And the fundamental theory of phase-shifting digital holography and some most commonly used phase-shifting algorithms of eliminating the conjugate image and the zero-order image are introduced in detail. Besides, the experimental setup of phase-shifting digital holography is described.(3) Because phase-shifting digital holography is highly demanding for the precision of the phase-shifting device, the more phase shifts are operated, the greater errors may be resulted in. So the single phase-shifting digital holography is studied and the optical setup is completed to reconstruct the 2D object and the 3D micro-scale reflected object.(4) The influence of different phase-shifting angles of reference wave in recording on the quality of the reconstructed image is investigated. Reasons resulting in the errors are analysed theoretically, and an iterative method is used to eliminate the phase-shifting error by calculating a sum the of amplitude deviation of the reconstructed image. The phase-shifting error could be eliminated by finding the phase-shifting angle when the sum of the amplitude deviation is the least and the effectiveness of the used method is verified.