This paper was invited for a special issue on Advances in Pattern Recognition, Techniques, Devices and Algorithms in Optical Engineering. This was EPSRC funded research (GR/L90774/01) and describes the construction of the optical/digital hybrid correlator invented in our group. The complex wavefront modulation method I developed in reference one was implemented within the correlator and the results are analysed. This technique later made it possible to realize difficult to implement filters such as the Wiener filter. The system demonstrates high speed pattern matching. This has been further developed by the IIT (joby@physics.iitd.ernet.in), and Richard Hartman of AOS Inc (hartman@aos-inc.com).