title: Method for edge detection based on phase jump in a differential interferometer.
abstract: We describe a new method for edge detection that uses polarization mixing in a differential heterodyne interferometer. When one of the focused beams of the interferometer scans across an edge, a phase jump of 180 degrees takes place in the very small region of the edge if certain conditions are satisfied. We call this phenomenon phase jump. The conditions in which phase jump can occur are given. The theoretical analysis shows that the slope of a phase jump is infinite and is not affected by step height, the vibration of the sample, or the intensity variation of the light source. Therefore phase jump can be used as the precise index for edge detection. The experimental results show good agreement with the theoretical analysis.
authors.affiliation: Department of Mechanical Engineering, Hong Kong University of Science and Technology, Hong Kong.
authors.forename: W
authors.initials: W
authors.lastname: Zhou
authors.forename: L
authors.initials: L
authors.lastname: Cai