title: Interferometry using binary holograms without high order diffraction effects.
abstract: We describe a technique for a phase-stepping interferometer based on programmable binary phase holograms, particularly useful for optical testing of aspheric or free-form surfaces. It is well-known that binary holograms can be used to generate reference surfaces for interferometry, but a major problem is that cross talk from higher diffraction orders and aliasing can reduce the fidelity of the system. Here, we propose a new encoding technique which improves the accuracy of the technique and demonstrate its implementation using a binary liquid crystal spatial light modulator.
authors.affiliation: Department of Physics, Indian Institute of Technology Guwahati, Guwahati-39, Assam, India. brboruah@iitg.ernet.in
authors.forename: Bosanta R
authors.initials: BR
authors.lastname: Boruah
authors.forename: Gordon D
authors.initials: GD
authors.lastname: Love
authors.forename: Mark A A
authors.initials: MA
authors.lastname: Neil