Optical correlator

An optical correlator is a device for comparing two signals by utilising the Fourier transforming properties of a lens. It is commonly used in optics for target tracking and identification.

The correlator has an input signal which is multiplied by some filter in the Fourier domain. An example filter is the matched filter which uses the cross correlation of the two signals.

The cross correlation or correlation plane, ${\displaystyle c(x,y)}$ of a 2D signal ${\displaystyle i(x,y)}$ with ${\displaystyle h(x,y)}$ is

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