Study On Three-Dimensional Display Based On Computer Generated Cylindrical Hologram

With people's increasing demands for visual information acquisition,the holographic three-dimensional display technology which can observe the object with naked eyes has attracted more and more researchers' attention.Computer Generated Hologram(CGH)has the advantages of high speed,convenient operations and can reconstruct the virtual objects,has become more and more popular with the scholars.However,the planar holograms can only observe the object in a single angle,it's difficult to realize full perspective reconstruction.Computer Generated Cylindrical Hologram(CGCH)can observe the object in 360°field of view.Therefore,our work studied CGCH which can obtain high quality reconstructed images.The detailed research contents are as follows:(1)In this paper,the Fresnel hologram and the kinoform of the three-dimensional globe model were coded,the reconstructed images of the three-dimensional globe model in different depths were obtained.The experimental results show that the Fresnel hologram or the kinoform can reconstruct the original three-dimensional object in a single angle and different depths.(2)The computer-generated cylindrical hologram system was established.The object and the hologram surface are concentric cylindrical surfaces,which ensures the translation invariance of the system,FFT can be used for fast calculation.Two reconstruction methods were introduced:cylindrical surface reconstruction and plane reconstruction.The conditions of the spatial frequency and sampling interval of the system that should be satisfied ware derived,the impact on the spatial frequency and the transfer function of the system by the radii of cylindrical cross sections and the wavelengths was analyzed by both theory and experiments.Peak Signal to Noise Ratio(PSNR)and Mean Squared Error(MSE)were used for evaluating the quality of the reconstructed images.Under the condition of satisfying the sampling theorem,choosing a larger radius of cylinder section and a smaller wavelength can obtain a clearer reconstructed image.The CGCH for a cylindrical object was coded and the reconstructed images were obtained in different angles.The reconstruction results show that the method studied in this paper can observe the object in 360°field of view through a single CGCH.(3)The tomographic computer-generated cylindrical hologram system was established.The plane tomographic method obtains the information of the object with a single angle and different depths.But in the tomographic computer-generated cylindrical hologram system,the three-dimensional object was sliced into cylindrical cross sections,every cylindrical cross section contains the information of 360°field of view of the object in a specific depth.At the same time,all the cylindrical cross sections and the hologram surface are concentric cylindrical surfaces,so that the tomographic computer-generated cylindrical hologram system retains translation invariance.the CGCH for a three-dimensional earth model was coded and the reconstructed images were obtained in different angles and different depths.The results show that the proposed method can obtain high quality reconstructed images in 360°field of view and different depths of the ordinary three-dimensional objects.