| Three-dimensional(3D)display technology can provide a stereoscopic vision information for human eyes,which could be widely used in many applications,such as medical treatment,military,and entertainment.Among the various 3D display approaches,holographic 3D display technology is regraded as an ideal true 3D display approach because it can record and reconstruct the whole information of a 3D object,including the amplitude and phase information,and present a natural 3D image with all depth cues for human eyes.However,the traditional optical holography is difficult to satisfy the requirement of real-time dynamic display owing to the limited refreshable rate of the current available holographic recording media.In recent years,with advances in spatial light modulator(SLM)technology and computer science,SLM-based dynamic holographic 3D display technology gradually becomes a research focus in the field of 3D display.Nevertheless,there exist several large gaps of the structure parameters between the current available SLM and the SLM that meet the requirements of holographic video display with high quality due to the current technical conditions,resulting in the limited space bandwidth product of the state-of-the-art SLM,which causes that the satisfactory holographic 3D video display may hardly be achieved by using the current available SLM.Furthermore,3D objects usually have complicated spatial structures and large information volumes so that the huge calculated and refreshable data volume of the hologram could increase the difficulty of real-time dynamic holographic 3D display.For the purpose of dynamic holographic 3D display,a series of research works are developed in this thesis,which surrounding with the existing key problems in SLM-based dynamic holographic 3D display technology.The main research contents and innovations of this thesis are outlined as follows:(1)The mechanism of SLM-based holographic display is systematically investigated.The characteristic parameters of holographic display,including resolution,size and viewing angle,are specifically discussed,and the influences of the structure parameters of the SLM on the characteristic parameters of the holographic reconstructed image are analyzed in detail.In the analysis of resolution,the pixel number,the point spread function(PSF),and the modulation transfer function(MTF)are employed to describe the resolution of the holographic reconstructed image,respectively.In the analysis of size,the reasons why the size of the holographic reconstructed image is severely limited are analyzed in detail,and the mosaic magnification method based on holographic reconstructed images of multiple SLMs is verified,and the expansibility of the method is pointed out.In the analysis of viewing angle,the current typical viewing angle enlargement methods are summarized,where the validity and expansibility of the approach to cicular tiling configuration of multiple SLMs are pointed out.Furthermore,the experimental verification system of holographic display with the enlarged viewing angle based on two SLMs is constructed,and the experimental results indicate that the viewing angle of the obtained holographic reconstructed image using two SLMs is wider than the viewing angle formed by a single SLM.(2)The basic priciples of typical hologram algorithms of 3D objects are introduced in detail.Moreover,the advantages of the tomography method are summarized,and the problem of the expression of the depth information in the tomography method is specifically discussed.In the Fourier holographic display system,multi-plane holographic 3D display is realized by using the programmable zoom lens to express the depth information.Subsequently,a multi-plane optical see-through holographic 3D display system for augmented reality(AR)applications is designed and constructed,and the verification experiment is performed.Furthermore,in order to simplify the optical path of the designed system above,a system optimization method is proposed by employing an off-axis holographic lens as the optical combiner,and the optimized experimental system is also constructed.In the Fresnel holographic display system,tomography Fresnel holograms are calculated and dynamically reconstructed by using the Fresnel diffraction distance to express the depth information.In addition,for the purpose of dual-view 3D display,a dual-view holographic 3D display method and its AR display method based on a zero-oreder nulled grating are proposed,where the zero-oreder nulled grating is theoretically designed and experimentally fabricated.Then the dual-view holographic 3D display system and its AR display system are constructed,and the synthetic hologram for the proposed dual-view holographic 3D display 1s also calculated by using tomography Fresnel diffraction algorithm.The experimental results demonstrate that the effects of dual-view holographic 3D display and its AR display are successfully achieved.(3)A binocular holographic 3D display method and its AR display method based on a single SLM and a grating light-guide plate are proposed,where the grating light-guide plate is theoretically designed and experimentally fabricated.Then the binocular holographic stereoscopic 3D display system and its AR display system are constructed,and the verification experiments are also performed.Subsequently,the cause of the accommodation-convergence conflict in stereoscopic 3D display is specifically analyzed,and the solution of the accommodation-convergence conflict in the binocular holographic stereoscopic 3D display system above is proposed by introducing the hologram generation method of 3D object.Optical experiments demonstate that the binocular holographic 3D images with both the accommodation effect and binocular parallax are successfully presented,which enables observation free of the accommodation-convergence conflict and visual fatigue problem.In addition,a binocular holographic AR 3D display method based on two SLMs is also proposed,and the experimental verification system 1s constructed.Furthermore,the software of a synchronous controlling system for playing holograms in two SLMs simultaneously is writed,and the experimental results prove that the effect of binocular dynamic holographic AR 3D display is successfully realized.(4)A multiview holographic stereoscopic 3D display method based on a single SLM and a directional diffractive device is proposed,where the directional diffractive device is theoretically designed and experimentally fabricated.Then the multiview holographic stereoscopic 3D display system is constructed,and the verification experiment is also performed.The experimental results indicate that the effect of multiview dynamic stereoscopic 3D display without crosstalk is successfully obtained.In addition,a multiview holographic stereoscopic 3D display optimization method is proposed based on multiple SLMs,and the experimental system of the optimized multiview holographic stereoscopic 3D display based on two SLMs is also constructed to verify the validty of the proposed optimization method.The experimental results demonstrate that the effects of full parallax stereoscopic 3D display and horizontal parallax stereoscopic 3D display with improved resolution are successfully achieved so that the effects of multiview holographic stereoscopic 3D display are optimized by using the proposed optimization method.Finally,the key technical indicator in the proposed multi view holographic stereoscopic 3D display method,the image resolution of each displayed view,is analyzed in detail,and the optimization direction of the resolution in the future is also pointed out. |
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