Page 370 - Introduction to Information Optics

Chapter 7 Pattern Recognition with Optics

FRANCIS T. S. Yu
PENNSYLVANIA STATE UNIVERSITY

The roots of optical pattern recognition can be traced back to Abbe's work*
in the 1870s, when he developed a method that led to the discovery of spatial
filtering to improve the resolution of microscopes. However, optical pattern
recognition was not actually appreciated until the complex spatial filtering
f
work of Vander Lugt in the 1960s. Since then, techniques, architectures, and
algorithms have been developed to construct efficient optical systems for
pattern recognition.
Basically, however, there are two approaches in the optical implementation
of pattern recognition the correlation approach and the neural net approach.
In the correlation approach, there are two frequently used architectures: the
Vander Lugt correlator (VLC) and the joint-transform correlator (JTC),
discussed briefly in Chapter 2. In this chapter, we address some of the basic
architectures, techniques, and algorithms that have been applied to pattern
recognition. The pros and cons of each approach will be discussed. Because of
recent technical advances in interface devices (such as electronically address-
able SLMs, nonlinear optical devices, etc.), new philosophies and new algo-
rithms have been developed for the design of better pattern recognition
systems.

* Reference I.
** Reference 2.
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