Commenting on the University of Colorado at Boulder’s announcement of its bit-serial optical computer (CI No 2,085), Professor Desmond Smith, who leads the Scottish Collaborative Initiative in Optoelectronic Sciences, SCIOS, (CI No 1,860) told Computergram that using optical fibre to create the computer’s memory is indeed a worthy and new development. But the Colorado University machine is not the only ever optical computer to have been built – Professor Smith and his researchers, and their counterparts at AT&T Co’s Bell Laboratories have all produced their own, and indeed work is continuing in Scotland on fourth and fifth generation models. Colorado’s method takes advantage of the fixed speed of light, which means that timings and delays can be set precisely by measuring out the lengths of fibre optic loops precisely. Professor Smith’s team uses a free space digital optics approach where two dimensional optical signals are used to transmit images without using optical fibres. This the same method that Colorado is intending to use in its proposed palm-top version which it says, will have millions of switches interconnected through free space using mirrors instead of fibres. The Scottish researchers, meantime, have produced Optical Cellular Logic Image Processors, OCLIPS for short, capable of 32 by 32 parallelism and are working on high speed data transmission: on GHz, Gbps to Tbps routes. Work is also progressing on interconnection of optical circuits, which relies on holograms to re-route optical signals.
