Homework 1 - Patent Selection
US Patent 4,188,122: Interferometer
This patent was issued on February 12, 1980 and describes a laser interferometer. That splits a coherent laser beam into a test beam and a reference beam that are orthogonally polarized. The test beam undergoes some sort of distortion (supposedly) and is then reflected back to be recombined with the reference beam. The returning beams are polarization filtered so that they will recombine to form an interferogram based on the distortions of the test beam. A photoelectric sensor measures brightness changes allowing point-by-point phase differences to be calculated electronically, and a contour map of the test beam's wave front can be constructed.
Link to the patent: