Long time readers may remember the 3D volumetric display developed by LightSpace Technologies (Latvia). The company never found a solid market for its product and went out of business. But now, they are back with a new and more promising variant...
How It Works
The LightSpace volumetric display is based on a single-chip DLP engine in a rear-projection monitor configuration. To create a volume of images, they assemble a series of addressable screens like a loaf of bread. They call these multi-planar optical elements (MOE) as they can be quickly changed from a transparent mode to a scattering mode allowing the image to become visible. If these "slices" are shown fast enough, a volume of images is visible to the eye.
In previous versions of this display, the MOEs were composed of a single cell of Polymer Dispersed Liquid Crystal (PDLC) material. But according to LightSpace Technologies CEO Ilmars Osmanis, the new MOEs do not use PDLC, but a new LC formulation.
The company has three display models. The second generation x1405 is available for ordering today with the x1406 available soon. The third generation x1500 is in development and should be ready by early Autumn. The table below shows the specs for the x1405 and the x1500. The x1406 is apparently similar to the x1405 except smaller, lighter and less expensive.
Bandwidth is Key
Clearly, bandwidth is an issue with a volumetric display. This is a single-chip engine, so it must run faster to create color images, and there are multiple image planes. Conventional DLP imager chip sets cannot power this type of display, which is why TI created their Discovery spatial light modulator device, which has much faster addressing capabilities. They apparently no longer use this name, so LightSpace uses the DLP 7000 DMD chip set for the x1405/1406 series, which supports 32K binary frames per second. As noted in the table, this has XGA resolution. The x1500 increases the resolution on the spatial light modulator to 2560x1600.
Currently, the color image is only 5-bits per color with a screen update rate of 20 Hz. Osmanis says that they buffer the incoming data at 60-70 Hz, but the data distributed to the display is limited by the interface bandwidth (DP 1.2), resulting in the 20Hz refresh rate. Osmanis says this won't get any better with the x1500 as the data rate will grow from 15 Gbps to 60 Gbps.
From 20 fps to 100 fps
While the company is moving to a quad DP1.4 interface which should offer an 8X increase in bandwidth (total of 129.6 Gbps), efficiently threading the data over these four pipeline won't be that efficient, so better to be conservative here. In addition, the frame rate will be limited by how fast the MOE elements can be addressed, so 20 fps is the top end for color image for now. However, if grayscale only images are displayed, the company has the option to offer 12 bps at around 50 fps or 5-8 bps at around 100 fps.
LightSpace echnologies has offices in Latvia, Twinsburg (OH,USA), and San Jose (CA,USA).