Computational Holography

A research group at Kansai University is doing research on computer-synthesized holograms.Computer-generated holograms are one type of holography. But as opposed to ordinary holography, where actual objects are photographed, this technology utilizes exactly the same techniques as CG, to create 3D images of virtual objects using light."One key point about this technology is that, to create an object as CG, it's necessary to calculate what happens to the light from an object. This takes a very long time. We use a machine with about 100 GB of memory, and the calculation takes 2-3 days. The images produced are extremely large - much bigger than Super HiVision, which is 8K x 4K. For example, these images are 64K x 64 K, or 128K x 64K, which is huge. They're produced by engraving with a pixel pitch of one micron."One effective way of manufacturing computer-generated holograms is the photo-mask technique. A micro-pattern is formed on quartz glass coated with a chrome film, and when light hits it, the pattern diffracts the light, forming a 3D reproduction that gives a strong impression of depth."This is the material we're currently making. The base is a glass plate. These are actually the same as the photomasks used to make ICs. The glass plate is coated with a chrome film. We form a pattern by using an ultra-fine processing machine to remove the chrome in pixel-sized pieces. The pattern has one-micron pitch, so it isn't visible to the human eye. But this plate is engraved with a pattern that's been calculated to produce an image when it reflects light."Currently, these holograms are small, and they only have one color. But from now on, the team wants to improve them further, and make them vividly colored.This system will be exhibited at SIGGRAPH 2010, in Los Angeles, from July 25.

Matsushima, Kyoji; Nakamura, Masaki; Nakahara, Sumio; Kanaya, Ichiroh: Computational Holography: Real 3D by Fast Wave-Field Rendering in Ultra-High Resolution; Proc. ACM Siggraph, 2010.