title: Resolving fringe ambiguities of a wide-field Michelson interferometer using visibility measurements of a noncollimated laser beam.
abstract: An actively stabilized interferometer with a constant optical path difference is a key element in long-term astronomical observation, and resolving interference fringe ambiguities is important to produce high-precision results for the long term. We report a simple and reliable method of resolving fringe ambiguities of a wide-field Michelson interferometer by measuring the interference visibility of a noncollimated single-frequency laser beam. Theoretical analysis shows that the interference visibility is sensitive to a subfringe phase shift, and a wide range of beam arrangements is suitable for real implementation. In an experimental demonstration, a Michelson interferometer has an optical path difference of 7 mm and a converging monitoring beam has a numerical aperture of 0.045 with an incidental angle of 17 degrees. The resolution of visibility measurements corresponds to approximately 1/16 fringe in the interferometer phase shift. The fringe ambiguity-free region is extended over a range of approximately 100 fringes.
authors.affiliation: Department of Astronomy, Bryant Space Science Center, University of Florida, Gainesville, Florida 32611, USA. xwan@astro.ufl.edu
authors.forename: Xiaoke
authors.initials: X
authors.lastname: Wan
authors.forename: Ji
authors.initials: J
authors.lastname: Wang
authors.forename: Jian
authors.initials: J
authors.lastname: Ge