Convergent Vander- Lugt optical correlator.

<p>O is a monochromatic source light, L1 and L2 are lenses, the scene and the filter planes hold both images to correlate and a CCD camera registers the correlation plane. The Fourier transform of the input image <i>s(x,y)</i> is obtained at the Filter plane where the optical correlation <i>S(u,v)H*(u,v)</i> takes place. The correlation result <i>c(x,y)</i> is captured by the CCD camera.