Optical computing

Abstract

Dozens of research workers in more than a hundred leading laboratories of the world are working on creating the foundations for a new field of engineering that promises to have a revolutionary impact on almost every field of science and tecFhnology. Resulting from the introduction of a variety of new techniques and devicesincluding the laser-as well as from the development of new photosensitive and electron-beam recording materials-including thermoplastics, codable films, and mass-storage holographic memories-this new technology, known as optical computing, is based upon mathematical concepts known as coherent or Fourier optics and holography.In terms of future developments and applications, the most dramatic results very likely will emerge from the implementation of real-time image processing in various forms. But the great power of optical computing derives primarily from its newly recognized capability of parallel processing, a natural property of the lens! In a general way, all aspects of this new field can be characterized by established concepts of electric and electronic signal processing and communications.Few applications of holography have had as great an optical computing processes is nothing short of amazing. impact on science and technology as the optical computer,As an example, modern synthetic-aperture radars scan an entirely new class of ultrahigh-speed, extremely highupward of 101 resolvable elements per second, making mass-storage data processors. In one noted application, photographic records (several kilometers long and onethis instrument already has succeeded in increasing the dimensional)-of zone pIates for each of these 10o elements. sharpness of images obtained from the most powerfulThe optical hologram process itself records and utilizes electron microscopes, way beyond the ultimate resolution detail that corresponds to 2000-3000 lines per millicapability of the microscope itself. In other applicationsmeter, equal to upward of 4 X 1010 picture elements in which range from fingerprint/credit-card identification each microscopic plane of a 10-cm-square hologram! to the a posteriori synthesis of large microwave an-The fact of the matter is that no presently known electennas-the optical computer has yielded results that far tronic computer has come even close to optical processing exceed the performance of even the most powerful digital in approximating the natural capacity of the lens to procomputers. * cess images (no more than the operation of the human The information-handling capability of the various brain can~be approximated by any known form of com-

Contrast constancy: deblurring in human vision by spatial frequency channels.

“…1 A). If the deblurring technique is used to give maximum reconstruction of the original, then the noise is also strongly amplified, and the final image is seriously degraded (see Stroke, 1972).…”

Visual control of orientation behaviour in the fly: Part II. Towards the underlying neural interactions

“…They can be selective for some specific feature of the input patterns; they can perform spatial frequency analysis; they underlie a variety of basic computations. An example of their computational possibilities is offered by the field of optical computation, where deblurring, image reconstruction, superresolution and even pattern recognition are implemented by parallel, distributed, linear systems (Stroke, 1972). However, nonlinear interacting networks can reveal a significantly more sophisticated pattern processing.…”

Multiple bandpass filters in image processing

“…In general it is the high-frequency components of the noise which cause most trouble, and these frequencies are the ones which are amplified most by deblurring. 16 To avoid excessive amplification of noise, it is usually necessary to adopt a compromise degree of deblurring, and only compensate those frequency components which are more likely to be due to the target than the noise. The optimal compromise depends critically on the signal/ noise ratio at different frequencies.…”