Multiview holographic 3D dynamic display by combining a nano-grating patterned phase plate and LCD

Limited by the refreshable data volume of commercial spatial light modulator (SLM), electronic holography can hardly provide satisfactory 3D live video. Here we propose a holography based multiview 3D display by separating the phase information of a lightfield from the amplitude information. In this paper, the phase information was recorded by a 5.5-inch 4-view phase plate with a full coverage of pixelated nano-grating arrays. Because only amplitude information need to be updated, the refreshing data volume in a 3D video display was significantly reduced. A 5.5 inch TFT-LCD with a pixel size of 95 μm was used to modulate the amplitude information of a lightfield at a rate of 20 frames per second. To avoid crosstalk between viewing points, the spatial frequency and orientation of each nano-grating in the phase plate was fine tuned. As a result, the transmission light converged to the viewing points. The angular divergence was measured to be 1.02 degrees (FWHM) by average, slightly larger than the diffraction limit of 0.94 degrees. By refreshing the LCD, a series of animated sequential 3D images were dynamically presented at 4 viewing points. The resolution of each view was 640 × 360. Images for each viewing point were well separated and no ghost images were observed. The resolution of the image and the refreshing rate in the 3D dynamic display can be easily improved by employing another SLM. The recoded 3D videos showed the great potential of the proposed holographic 3D display to be used in mobile electronics.