and included in the simulation to verify the belief that its effect is

negligible. More simulation runs on a wide variety of images would

better determine the interaction of image parameters with hologram

performance.

 Optical processors will provide low cost and high speed pattern

 recognition for specific tasks.68 It must be noted, however, that

 Vander Lugt-type optical pattern recognizers are very limited in their

 application. The correlation process is hard-wired into the optical

 computer and the pattern recognition algorithm cannot be modified.

 This is in contrast to the slower digital processors which are

 software-controlled to perform a wide variety of image functions. The

 Vander Lugt correlator will fill a near-term need for a cheap

 processor of moderate performance in a controlled environment. This

 works well for machine vision application where the in-class and out-

 of-class patterns are well known. Performance of such a hard-wired

 system drops when the target is in a hostile environment.

 The next generation of optical processors must be able to adapt

and learn. Such a device must support a wide variety of algorithms at

a speed compatible with the application. Future research in this area

should address the need for optical processors which not only perform

Fourier transforms and correlation, but many other functions as well.

This could be accomplished using real-time spatial light modulators as

holographic elements. The hologram might perform as a holographic

lens for Fourier transforming or it might perform a coordinate

transform depending on the command of a digital, high level, image

understanding algorithm. Such a flexible processor should prove

successful for the next generation of pattern or target recognizers.