Three-dimensional Objects In Digital Holography And Its Application

Digital holography is a novel optical branch compound of conventional optic holography and computer technology. Besides the advantages of conventional holography, it avoids the wet chemic process and obtains the object wave field easily through calculation. 3D object digital holography can record and reconstruct the amplitude and phase of 3D object, which is especially good for the analysis and measurement of the object surface topography and is attracting the attention of researchers around the world.The quality of the reconstructed image directly calculated from the recorded hologram is unsatisfactory because of the presence of the zero-order diffraction and the speckle noise. This paper focuses on the various methods for improving the quality of the reconstructed images in order to put them into practical usage. The methods presented in this paper include the off-axis recording method to separate the object images, the mean method to suppress the zero-order diffraction, the phase-shift method to eliminate the zero-order diffraction and the conjugated image, the wavelet analysis method to eliminate the zero-order diffraction and reduce the speckle noise, the contracted weighted mean filter to enhances the contrast and exquisiteness of the reconstructed images, the curvelet method to reduce the speckle noise and protect more edge information, the fusion method to reduce the speckle noise. Every method is deduced from theory analysis and proved by satisfactory experimental results.This paper explores the application of 3D object digital holography through two ways which are digital holographic interferometry and 3D object pattern recognition. In digital holographic interferometry, we can accurately measure the slight deformation of the object by calculating the change of the phase information recorded by digital holograms. In 3D object pattern recognition, the rotation tolerant three-dimensional object pattern recognition was achieved by constructing nonlinear filter based on the information extracting from reconstructed images.In this paper, all the researches for 3D object digital holography is carried out by single exposure method. For recording hologram only once, it is convenient for applications on the real time image processing fields.