The pixel count of hologram for a holographic 3D display system increases rapidly with the increase in reconstructed
object size and viewing angle. According to our analysis, for 10 inch reconstructed object size with 5° viewing angle, a
hologram with a pixel count of 378 Million is required. Such a large pixel count is a challenge for both hologram
computation and hologram data transmission. The computation load is analyzed to be a few hundreds of Tflop for the
object with a few million object points, and the hologram data transmission rate required is analyzed to be 22.3 Gbps and
67.0 Gbps for monochrome display and color display using time division multiplexing at 60 Hz, respectively. A
computer cluster with 32.7 Tflops GPU computing ability and 60 Gbps transmission bandwidth was built to meet the
hardware requirements for large-pixel-count hologram computation and transmission. A distributed computation method
was implemented for computing large-pixel-count holograms. Computation time of 5.6 seconds was achieved for 378-
Mpixel hologram containing information of 1.7 M object points. During the playback of holographic video using our
holographic 3D display system, the hologram data was read out from SSDs, transmitted over the high speed network,
and finally launched onto SLMs for reconstruction. A data transmission rate of 31.8 Gbps was achieved, which
corresponded to 378-Mpixel hologram at 84 Hz for monochrome reconstruction and full color reconstruction using space
division multiplexing. The increasing demand for computation power and data transmission rate of large-pixel-count
hologram video displays has been effectively addressed.
We have developed a full-color full-parallax digital 3D holographic display system by using 24 physically tiled SLMs, an optical scan tiling approach and two sets of RGB lasers, which could display 378-Mpixel holograms at 60 Hz, with a displayed image size of 10 inch in diagonal. In this paper, we will review and compare three different holographic display systems developed by our group from various aspects, including SLMs, lasers, optics designs, hologram computation, data transmission, and system synchronization. We will also discuss the bottlenecks and prospects of further development of the system for practical applications.
We present a novel approach that utilizes both physical tiling and optical scan-tiling of high-speed electrically addressed spatial light modulator (SLM) for increasing the pixel count of hologram. Twenty-four SXGA (1280×1080) high-speed ferroelectric liquid crystal on silicon are first physically tiled to form an 8(rows)×3(columns) SLM array. This array is further tiled to form a final hologram with pixel count of 377.5 Megapixels through a 1-axis galvanometric scanning mirror. A large computer-generated hologram is calculated and fed into the individual SLMs according to the predefined sequence. Full-color and full-parallax flickless three-dimensional objects are replayed at a rate of 60 frames per second in a 10-in. display window. The launching of the hologram, laser illumination, and scanning mirror are synchronized and controlled by a field-programmable gate array.
In this paper, a full parallax occlusion algorithm for holographic 3D display is developed and the motion parallax and
dynamic occlusion effect of the reconstructed 3D object is successfully demonstrated. The ray-casting, directional
clustering and vertical angle marking technologies are integrated with coherent ray tracing (CRT) hologram computation
algorithm. By applying the vertical angle marking technology, only a single pass of the entire horizontal viewing angle is
needed to compute full parallax occlusion. The complexity of the algorithm is reduced by about one order compared to
standard occlusion algorithm which considers the entire range of combination of horizontal and vertical viewing angles
for occlusion. Compared to conventional CRT computation which does not consider occlusion effect, the algorithm has
also increased the computation speed to about 350%. The algorithm is able to work with any forms of 3D data. The
optimal horizontal angular resolution has also been identified as 0.007 degree for our system experimentally which
enables the optimization of the algorithm. Various 3D objects with full parallax occlusion effect have been reconstructed
KEYWORDS: Holograms, Holography, Digital holography, Data storage, Computer generated holography, Spatial light modulators, Algorithm development, 3D displays, 3D image processing, 3D optical data storage
Holographic display is a true three-dimensional (3D) display technology presenting all depth cues without using any special
glasses. In this paper, we first introduce a monochrome digital 3D holographic display system developed at Data Storage
Institute (DSI), which is capable of displaying both static and dynamic 3D objects reconstructed from computer-generated
holograms (CGHs). The system can also display 50-Mpixel holograms at 25 Hz refresh rate via a novel hologram tiling
approach, which enables the increase of displayed image size. A futuristic vision for full high-definition (HD) digital 3D
holographic display is then proposed and analyzed. The dynamic reconstruction of full-HD 3D objects from CGHs has been
preliminarily demonstrated. Finally, we introduce the development trends of its enabling technologies such as highperformance
computing, new algorithms, data storage and transmission, spatial light modulator (SLM) and RGB (red, green
and blue) laser sources.
The current limitation in pixel count of a single spatial light modulator (SLM) is one of the technological hurdles that must be overcome to produce a holographic 3-D display with a large image size. A conventional approach is to tile subholograms that are predivided from a reconfigurable computer-generated hologram (CGH) with a high pixel count. We develop a new approach to achieve a 50 Mpixel display by tiling reconstructed subholograms computed from a predivided 3-D object. The tiling is done using a two-axis scanning mirror device with a new tiling sequence. A shutterless system design is also implemented to enable effective tiling of subholograms. A high-speed digital micromirror device (DMD) at 6 kHz with 1920×1080 pixels is utilized to reconstruct the subholograms. Our current system shows the potential to tile up to 120 subholograms, which corresponds to about 240 Mpixels. The approach we demonstrate gives a scalable solution to achieve a gigapixel-level display in the future.