Electronics Weekly Electronics Design & Components Tech News
Previously demonstrated privately alongside an optical conference in the US earlier this year, the device was shown to Electronics Weekly at the firm’s St John’s Innovation Centre headquarters.
The projector builds up an image by modulating red, green and blue lasers with an electronically controlled hologram on a small LCD.
Each pixel of the LCD, which is a fast bistable ferroelectric type, is switched to produce either 0 or phase shift for each colour of each frame.
Noise in the image is reduced by projecting multiple copies of each colour in each frame and allowing the viewer’s eye to integrate.
Resulting interference in each sub-frame produces an image which is in focus from just in front of the projector to infinity.
The image actually leaves the modulator with a narrow divergence angle which is broadened by anything up to 115 degrees by a two-lens group.
A considerable amount of number-crunching goes into driving the LCD, using algorithms developed by the firm.
These algorithms allow the image to be: pointed in any direction within its angular limits, and altered in geometry.
For example, imagining the projector like a small camera standing on a desk, the image could be computed for a vertical screen sitting on the desk, or for the desk surface in front of the projector. Both would be neat, rectangular and focused images, and no change in the optical path would be required to switch between the two.
For commercial reasons the firm could not reveal its size roadmap, but predicts its products will eventually be built into phones and PDAs.
What was it like?
Electronics Weekly can confirm that the display as demonstrated produced a vibrant near-A5-sized movie clip in a dimmed room with no apparent display artefacts apart from laser ‘speckles’. “We have a programme on-going to reduce speckling to an acceptable level,” said acting CEO Dr Chris Harris.
Unlike Light Blue’s cigarette-packet-sized monochrome demonstrator, the colour prototype is built on an optical bench that includes three (RGB) lasers and combining optics as well as a spatial light modulator and two lenses to control the size of the final image.
