

Optalysys and Optical Computing - _cody
http://scottlocklin.wordpress.com/2014/08/11/optalysys-and-optical-computing/

======
beambot
Incidentally, this notion of optical computing has some interesting roots in
the radar community.

From the Wikipedia page on synthetic aperture radar:
[http://en.wikipedia.org/wiki/Synthetic_aperture_radar](http://en.wikipedia.org/wiki/Synthetic_aperture_radar)

 _Before rapid digital computers were available, the data processing was done
using an optical holography technique. The analog radar data were recorded as
a holographic interference pattern on photographic film at a scale permitting
the film to preserve the signal bandwidths (for example, 1:1,000,000 for a
radar using a 0.6-meter wavelength). Then light using, for example,
0.6-micrometer waves (as from a helium–neon laser) passing through the
hologram could project a terrain image at a scale recordable on another film
at reasonable processor focal distances of around a meter. This worked because
both SAR and phased arrays are fundamentally similar to optical holography,
but using microwaves instead of light waves. The "optical data-processors"
developed for this radar purpose [2][3][4] were the first effective analog
optical computer systems, and were, in fact, devised before the holographic
technique was fully adapted to optical imaging. Because of the different
sources of range and across-range signal structures in the radar signals,
optical data-processors for SAR included not only both spherical and
cylindrical lenses, but sometimes conical ones._

