Optical EngineeringHolographic lenses for performing complete Fourier transformations
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A quadratic-phase holographic lens can give a Fourier transform that is multiplied by an undesired parasitic phase, caused by the off-axis configuration. We show that it is possible to significantly reduce the parasitic phase by controlling the recording and readout geometries of the holographic lens so as to allow complete Fourier transformation. As a practical example we incorporate such a holographic lens into a conventional coherent light correlator, and show how to optimize the correlation peaks even when the illumination wavelength of the correlator differs from that used when recording the holographic lens and the filter.