Patent ID: 7312875
Filing Date: 2007-12-25
Classification: G03H

Abstract:
1. A method of obtaining a differential-phase spatially-heterodyned hologram at a beat wavelength defined by a first wavelength and a second wavelength, comprising: digitally recording a first spatially-heterodyned hologram at the first wavelength, the first spatially-heterodyned hologram including spatial heterodyne fringes for Fourier analysis; and substantially simultaneously digitally recording a second spatially-heterodyned hologram at the second wavelength that is different from the first wavelength, the second spatially-heterodyned hologram including spatial heterodyne fringes for Fourier analysis; then Fourier analyzing the recorded first spatially-heterodyned hologram by shifting a first original origin of the recorded first spatially-heterodyned hologram including spatial heterodyne fringes in Fourier space to sit on top of a spatial-heterodyne carrier frequency defined as a first angle between a first reference beam and a first object beam; Fourier analyzing the recorded second spatially-heterodyned hologram by shifting a second original origin of the recorded second spatially-heterodyned hologram including spatial heterodyne fringes in Fourier space to sit on top of a spatial-heterodyne carrier frequency defined as a second angle between a second reference beam and a second object beam, the first angle and the second angle not substantially equal; applying a first digital filter to cut off signals around the first original origin and performing an inverse Fourier transform on the result; applying a second digital filter to cut off signals around the second original origin and performing an inverse Fourier transform on the result; and then determining a difference between a filtered analyzed recorded first spatially heterodyne hologram phase and a filtered analyzed recorded second spatially-heterodyned hologram phase.