Research For True Color Reflection Holography By The Combination Of Computer And Optics

Holography is optical wavefront recording and reconstruction technology. As an important kind of three-dimensional display technology, holographic display has been considered as the most promising method and researched as a focus, because it enables people to feel the pefect and realistic three-dimensional images.The holograms of portraits, clouds and other objects can not be designed with traditional optical holography for its low coherent and highly equipment requirements. A novel technique is proposed based on the combination of computer-generated holography and reflection holography, which can overcome the limitation of optical holography. This technique can record real-existing objects and virtual objects, and achieve the reconstruction image by white light illumination.Compared with the monochrome holography, true color holography with the distinct characteristics such as truly reflecting the original object,vivid image and bright color is widely used in art-design,cultural treasures’s saving and exhibition as well as other fields. In this paper, we focus on the reconstruction of color portraits with the combination of Computer-generated holography and reflection holography. In this method,we use a single continuous output laser rather than using plused laser for its security reason to record reflective hologram. Based on the knowledge that the processing condition of reflection hologram has an important effect on optical reconstruction, we control the shrink or swell of emulsion by different chemical processing to change the reconstructed image’s color. This kind of hologram can be optically reconstructed with white light. This thesis is arranged as fellows:Firstly:Simple reviews of holography development,3D display technique are presented. The characteristics of optical reflection holography and Computer-generated holography are analyzed. We classify the hologram by their properties and their merits and drawbacks. The effects on3D display of holography and the trend of3D display technique are also concluded in this section. In addition, we detailed illustrate the basic ideas and method of this paper.Secondly:The basic principles of computer-generated holography, the fundamental algorism of fresnel hologram and the theory of three-primary colors are detailedly introduced.Thirdly:With the combination of computer-generated holography and reflection holography, computer-generated holographical3D display is realized with the reflection holography. A3D scanner is used to obtain3D data of a real-existing object and calculate Fresnel holographic transmission distribution by point cloud algorithm. The Fresnel hologram is outputted by a holographic microfilming system. And, the reconstructed real image H1of the computing hologram is used as the recording object for optical reflection hologram. At last, we analyze the quality of reconstructed image.Some facts which affect color of reconstruction image during the processing of holographic silver halide plate are analyzed. Bsed on a lot of experiments, a method of emulsion contraction which determines the diffraction wavelength of the reflection holography is given. And this technique provides theoretical and technical basis for recording color reflection holography by single-wavelength.Different chemical processing conditions influence the wavelength of reconstructed image according to the emulsion contraction of silver halide plate. We exploit the necessary treatments to get three primary color image by recording numerous reflection holographical gratings.Last:The method to produce true color reflection hologram is seriously stressed. First, we design three monochrome computer-generated Fresnel holograms Hlr Hlg Hlband then three reflection holograms are record respectively by Hlr Hlg and Hlb. Three primary color holograms are obtained with different chemical processing conditions.Finally with the superposition of three primary reflection holograms, we obtained true color reflection hologram of a real portrait.In a conclusion, based on the study of computer-generated holography and reflection holography, we propose a new method to design true color reflection hologram with monochrome holographic plate. Firstly we prove the validity of this method, and then we successfully produce a true color reflection hologram by a large number of experiments. The method we presented enhances the flexibility and practicability of holographic display, which will further broaden application areas of holographic display.