Research On Computer Hologram Algorithm Based On Three-dimensional Display

Compared with traditional holography,computer-generated hologram has great advantages.It owns the characteristic such as simple to prepare,easy to store,capable to calculate virtual objects and so on.Therefore,computer-generated hologram has played an increasingly important role in the field of three-dimensional display with the further development of computer technology.This thesis focuses on the algorithm of calculating holograms of three-dimensional objects.This paper first analyzes the relationship between the sampling rate of the hologram and the reconstructed distance in holography.And based on this,the hologram of multi-plane three-dimensional object and the object with continuous depth changes are calculated by the algorithm based on non-uniform Fourier transform is studied and the numerical simulation was carried out.The feasibility of the method is verified,which is a foundation of the follow-up discussion.Secondly,algorithm of computer-generated hologram from scaled 3D object of arbitrary viewing angle is studied.The spectral relationship between the object and its diffraction wavefront in three-dimensional space is analyzed,and the hologram is generated by the diffraction algorithm based on three-dimensional Fourier spectrum.At the same time,the traditional Fourier transform is replaced by the convolution-based Fourier transform,which breaks the fixed relationship of the sampling rate in the transform.Combining these,the spatial sampling rate can be flexibly adjusted so that 360 ° full-angle objects of different size can be calculated and reconstructed.The hologram has been reconstructed well by both numerical simulations and optical experiments.This makes sense for the research of dynamic three-dimensional display.Finally,the stereoscopic hologram algorithm based on non-uniform sampled wavefront recording plane is also studied.The principles of non-uniform sampling and wavefront recording plane related algorithms are analyzed in detail and are applied to the calculation of stereoscopic hologram.In this way,the application of non-uniform fast Fourier transform(NUFFT)and fast Fourier transform(FFT)in diffraction calculation effectively improves the calculation speed.The single object with certain depth and the scene composed by separated objects have been calculated,respectively.Effective reconstructed results were shown from the holograms.Meanwhile,the images of different perspectives have also been calculated and reconstructed and motion parallax with occlusion effects were observed.