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Modulation efficiency of double-phase hologram complex light modulation macro-pixels

The modulation efficiency of the double-phase hologram macro-pixel that is designed for complex modulation of light waves is defined and analyzed. The scale-down of the double-phase hologram macro-pixel associated with the construction of complex spatial light modulators is discussed.

Enhancement of the effective viewing window for holographic display with amplitude-only SLM

We propose the effective viewing window enhancement method for a holographic display with an amplitude-only SLM by using algorithmic approach. The basic concept is the superposition principle of holography. The multiple computer generated holograms (CGH) can be displayed on the SLM, and multiple 3D images are reconstructed at different positions within a viewing window simultaneously. In the experiments, we have implemented the holographic display using an amplitude-only SLM, a field lens, and laser light sources. We can observe the holographic 3D image in the frustum formed by the field lens through the viewing window located in the Fourier plane of the hologram. To enhance the effective viewing window, we generate multiple CGHs with an observer’s eye positions, and then overlap them to make the final CGH. Multiple 3D images can be reconstructed in different positions within the theoretical viewing window from the CGH displayed on SLM. This makes the enlargement of viewing zone that can observe the holographic images. The multiple holograms can be also made for enlargement of the viewing window along both horizontal and vertical direction (2D enlargement viewing zone). We confirmed that the experimental results and the simulation based on Rayleigh-Sommerfeld theory match well.

Ultra-slim coherent backlight unit for mobile holographic display

We propose slim coherent backlight unit for a mobile holographic display. This backlight unit consists of glass substrate for waveguide and two surface gratings produced by two-beam interference. The area of backlight illumination is 150 by 85 mm, and the thickness is 0.7 mm, which is thin compared to other conventional coherent backlight units. This backlight unit exhibits a total efficiency of 0.1%, preserving the collimation and a uniformity of 80% over the whole area. The proposed slim coherent backlight can be applied to a mobile holographic display.