A simple way to synthesize a shift, fully rotational and limited size invariant composite matched spatial filter for a coherent optical correlator is proposed. We use circular harmonic components of the same order of a reference pattern in different sizes as the training images instead of using the whole reference pattern in different orientations and different sizes as is reported by other workers. This saves much labor and time in the synthesis of the filter. In this article, we have synthesized a simple filter containing four second order circular harmonic components of the alphabetic letter `E' in four relative sizes 1, 1.17, 1.33, and 1.5. Results of computer simulation have shown that this filter is shift, fully rotational and limited size invariant over the size range from 1 to 1.5. Computer simulation has also shown that this filter possesses discriminating ability.

Date Published: 30 October 1992
PDF: 9 pages
Proc. SPIE 1812, Optical Computing and Neural Networks, (30 October 1992); doi: 10.1117/12.131215

Published in SPIE Proceedings Vol. 1812:
Optical Computing and Neural Networks
Ken Yuh Hsu; Hua-Kuang Liu, Editor(s)