A time-integrating optical correlator has been devised in which a digital shift register-LED array combination provides the delay-and-multiply operation usually performed by an acousto-optic cell. The optical subsystem is extremely compact and should be able to operate at bandwidths from D. C. to 100MHz. Delay time range and resolution can be varied over a wide range simply by changing the frequency of the clock driving the shift register.
Fred B. Rotz, Fred B. Rotz,
"Compact,Time-Integrating Optical Correlator With Variable Time Scaling", Proc. SPIE 0241, Real-Time Signal Processing III, (24 December 1980); doi: 10.1117/12.959240; https://doi.org/10.1117/12.959240