Amplitude encoded phase-only filters for optical correlators
AssigneeThe United States of America as represented by the Secretary of the Air Force
InventorJoseph L. Horner
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Abstract
Method allows a first phase-only optical correlator filter function to be written on an amplitude modulating device such as a spatial light modulator (SLM) by applying a bias term to the phase only filter function great enough to obtain a second amplitude encoded filter function, for use with a more economical amplitude responsive SLM.
Claims19
Method of modifying and utilizing a continuous phase-only filter, suitable for use in the Fourier Transform plane of an optical correlator, to enable said filter to be written on a pure amplitude responsive writing device comprising the step of:
- adding a bias term K2 to a first filter function H.sub.AP (u,v)=K.phi.(u,v), said bias term having a value great enough to obtain a second amplitude encoded filter function H.sub.AP =K[k2+.phi.(u,v)]where all phase angles are positive real numbers or zero and K is a linear sealing factor.
Method of producing an amplitude encoded binary phase-only filter which may be recorded upon a pure amplitude writing device comprising the steps of
- (a) binarizing a first phase only filter H(u,v)=exp[-j .phi.(u,v)];
- and
- (b) adding a bias to said first phase only filter, said bias having a value great enough to produce a second amplitude encoded filter having elements of real non-negative numbers, thus enabling said second filter to be written on a pure amplitude responsive writing device.
Dependencies are inferred from the claim text.