Page 383 - Introduction to Information Optics

368 7. Pattern Recognition with Optics

(o) (b)

Fig. 7.16. Output irradiance obtained with a 3 x 3 replicated JTPS array, (a) Using coherent
readout, (b) Using partial coherent readout.

7.2.2. NONZERO-ORDER JOINT-TRANSFORM DETECTION

The most important aspect of using hybrid optical architecture is the
exploitation of the parallelism of optics and the flexibility of the electronic
computer. JTC is known to be more robust with easy implementation, but the
conventional JTC suffers from poor detection efficiency, particularly for multi-
target and high-background noise environments. These drawbacks are pri-
marily due to the existence of the zero-order spectra. The zero-order spectrum
can be easily removed, however, by simple computer intervention.
Let us look at the JTPS, as obtained from the joint-transform duty cycle as
given by

2
2
q] = \F(p, q)\ + \R(p, q}\ + F(p, q}R*(p, q)
•exp(-2Dc 0p) + F*(p, q)R(p, q) (7.7)