Research On Computer Generated Hologram Near Eye Display Using LCOS

In recent years,near eye display has been widely used in various fields,especially in the field of military and consumer.For example,Google Corporation's Google glass,Facebook Oculus,Microsoft's Hololens and Magic Leap,without exception,to show the world that near eye display has great application prospect.The reason is that the near eye display provides the traditional display device does not have the real-time interaction with the real environment,gives the user a new visual experience.However,the traditional near eye display optical system frequently use holographic gratings,waveguides,free-form surfaces,refraction and reflection components,etc.,increasing the complexity of the system.Holographic displays as a simple structure of true three-dimensional display technology,has great prospects in the near-eye display.But the traditional holographic technology cannot be independent of the dynamic display,such as holographic grating as a light splitting element.In recent years,with the improvement of processing technology,the performance parameters of LCOS are getting higher and higher,and the quality of display based on LCOS is better and better,So J.-S.Chen,Xinzhu Sang et al proposed a near eye display scheme based on computer generated hologram(CGH).Based on the previous research of CGH near eye display technology,in this paper,the basic structure of LCOS,the principle of LCOS phase modulation,the scalar diffraction theory and the design method of diffractive optical elements are briefly analyzed,and the process of making and reproducing the computer-generated hologram is analyzed.Secondly,the LCOS imaging theory and phase characteristics are analyzed,and the digital raster is used to remove the zero order bright spot after the reconstructed image is shifted.According to the different phase modulation of LCOS with different wavelength,this paper proposes a wavelength division multiplexing color CGH algorithm.In order to provide a portable near eye display device,a scheme for dynamic display of single diffractive optical elements is proposed.Thirdly,a new holographic acceleration algorithm is proposed,the hologram can be obtained by only one Fourier transform,after adding the convergent light and the random phase distribution on the target surface,and the shot noise can be effectively reduced.In order to enlarge the field angle and effectively filter out the multi-order diffracted light and the zero-order bright spot,A CGH near-eye display system based on LCOS with reference 4f system is designed.In order to verify the rationality of the design system,the experimental system is set up and the experimental results are analyzed.At the end of this paper,we present the problems encountered in the CGH near-eye display technology and predict possible improvements.