Patent ID: 7177550
Filing Date: 2007-02-13
Classification: H04B

Abstract:
1. A method for receiving high frequency signals transmitted through free space, comprising: passing one or more optical signals, the one or more optical signals containing data and being composed of radiation of a plurality of differing wavelengths, through a diffractive optical element to form a plurality of signal segments, each signal segment having a different mean wavelength; passing a portion of a beam comprising each of said one or more optical signals through a phase retarder that is provided separately from said diffractive optical element, wherein said portion of said beam passed through the phase retarder comprises an area of the beam that is less than a total area of the beam in cross-section, wherein said phase retarder has an area that is less than an area of said diffractive optical element, wherein a first portion of the optical signal is passed through said phase retarder, wherein the first portion of the optical signal has a different phase than a second portion of the optical signal that is not passed through the phase retarder, and detecting data in each of said plurality of signal segments at or near a different spatial focal point, wherein a portion of said plurality of said detected signal segments has passed through said phase retarder.