In effect, each image transmitted through the stack using a collimated incident beam was modulated by the phase plate, with the nanogratings re-directing the emergent beam to the four viewing points as initially computed. In principle, the same concept could be applied with many more views (sub-pixels) all fixed as nanogratings whose periods and orientations are carefully computed once for all to generate a fixed number of views. Here the phase plate acts optically as a computational shortcut for all subsequent views that could be computer-generated (only with the light modulation information needed to drive the LCD display).
The researchers measured an angular divergence of only 1.02 degrees on average, slightly larger than the diffraction limit of 0.94 degrees. In their experiments, the researchers used a green collimated laser as their light source and were able to display real-time 3D video without ghost image or crosstalk. In the same paper, the researchers also reported 64-view 3D static images with 50º of field of view (FOV) by only using a binary mask.
They expect to be able to increase the resolution of the stereoscopic images and the refreshing rate through the use of a higher performance spatial light modulator. As future work, the researchers also envisage the use of collimated illumination through a waveguide (which could more easily transfer to mobile integration), and the integration of RGB colour filters to achieve full colour holographic video.
Visit SVG Optronics at www.svgoptronics.com
Visit Soochow University at https://eng.suda.edu.cn