Research For Circular-Viewing Plane Hologram By Combining Computer With Optical Holography

Three dimensional display technology is a new technology that can display3D informa tion of objects.It can not only provide stereo images for enjoying,but also provide guidance for the study of stereo vision and stereo display equipments.Human stereo vision include convergence,regulation,binocular parallax etc.Three dimensional technology include stereo scopic technology,automatic stereoscopic technology,volumetric3D technology,holograph y technology.Holography is the best3D display method for human natutal viewing which can be divided into two processes:recording and reconstructing.Optical holography often involve four steps:exposure,developing,fixing and bleaching.Now digital holography is the main trend of development of holography.It involve digital holographic detection technolo gy which record hologram by CCD then reconstruct it through computer,and computer-gen erated holographic technology which use3D surface measurement technology to obtain ob jects’information,and calculate hologram through computer then print it.Circular-viewing hologram break through the restrictions of traditional holography.It can provide360°reconstructed images, mainly involve cylindrical type,conical type,plane type etc.Cylindrical hologram was firstly proposed,and the computer-generated cylindrical hologram,computer-generated cylindrical rainbow hologram,computer-generated cylindric al rainbow color hologram has received great propress.Circular-viewing plane hologram can not only provide360■reconstructed images but also convenient for moving and carrying.It was firstly proposed by Dian-min WANG and then vigorously developed. While only researchers on abroad made the computer-generated plane circular-viewing rainbow hologram(CGPCRH) by using the synthetic technology.There is no demestic research so far.CGH can realize3D display of virual or dynamic objects.It can be divided into three main steps:3D information acquisition,computer calculation and coding,hologram’s output process.There is Romayn’s phase alternate coding method,modified off-axis reference light coding method etc.Our digital hologram output system can print CGH directly and fast. CGRH imitate the second step of two-step rainbow holography,and greatly reduced computation by separating the variables under the line hologram model.We propose CGPCRH calculation model by replacing narrow strip slit with circular slit.Point cloud method regard the object as a collection of numerous points. We deduce the intensity distrib ution in hologram plane of one point,and discuss the relationship between spatial frequenc y and object’s size.Simulation is carried out to verify the algorithm.To solve the problem th at point cloud method spend too much computation time,the FFT fast algorithm is propose d,including2D picture generation algorithm,stereoscopic circular-viewing hologram calcul ation principle,reconstruction principle.Then we calculate the image points’position and slits’position corresponding to different reconstructive wavelenghs.In order to explain the advantage of stereoscopic FFT method,finally we comparise the computation time of these two methods when point number change.Optical holography has the advantages of high resolution and no size restriction,these are also the shortcomings of CGH.Therefore,optical holography must be used in order to m ake a wide viewing-angle and large size hologram. We analyze holography spatial frequenc y when select different reference light,and choose spherical reference light whose point source located on axis.We calculate every details of imaging process for the purpose of designning optical setup.According to the parameters of CGH,we design the reflective and transmissive type circular-viewing plane hologram,then give the schematic diagram of reconstruction device. At last, we successfully complete the work of optical hologram photo graphy.Existing problems on experiment are analysised and prospect future works that can be carried out.In general,this paper is based on CGH and circular-viewing holography,propose the theory of combining optical holography and CGH to make large side viewing-angle circula r-viewing plane hologram. And verify all the principles through simulation and experiment. This work promote the practical way for3D display,so it has important application value.