Patent ID: 7286243

Claim:
A device for measuring the complex reflectance of light reflected off of a sample surface, comprising: means for generating a light beam with a known polarization state; means for focusing the light beam substantially normal onto the surface of the sample such that various rays within the focused light beam create a spread of angles of incidence θ with respect to the sample surface, wherein the focused light beam reflects off of the sample surface; means for producing a relative retardation in phase between parallel and perpendicular polarization states of the light beam; means for generating interference between the parallel and perpendicular polarization states of the reflected light beam; detector means positioned in the path of the reflected light beam having a two dimensional array of detector elements for receiving the reflected light beam and producing intensity signals in response thereto, wherein each of the detector elements corresponds to a unique angle of incidence θ and azimuthal angle φ of the reflected light beam; and a processor means for calculating magnitude and phase values for the reflected light beam by using the intensity signals corresponding to at least one incident angle θ and a plurality of azimuthal angles φ within the at least one incident angle θ sufficient to enable a meaningful Fourier analysis thereof, and for determining a physical characteristic of the sample based on the calculations; wherein the retardation producing means and the interference generating means are stationary and oriented such that the signals from the detector have a first Fourier component that is dependent on azimuthal angle 2 φ and a second Fourier component independent of the first Fourier component that is dependent on azimuthal angle 4 φ.