title: Focus detection criterion for refocusing in multi-wavelength digital holography.
abstract: The majority of focus detection criteria reported is based on amplitude contrast. Due to phase wrapping, phase contrast was previously reported unsuitable for focus finding tasks. By taking the advantage of multi-wavelength digital holography, we propose a new focus detection criterion based on phase contrast. Experimental results are presented to prove the feasibility of the developed criterion. Possible applications of the developed technology include inspecting machined surfaces in the auto industry.
authors.affiliation: Department of Mechanical Engineering, University of Michigan—Ann Arbor, 1210 HH Dow, 2300 Hayward Street, Ann Arbor, Michigan 48109, USA. xulium@umich.edu
authors.forename: Li
authors.initials: L
authors.lastname: Xu
authors.forename: Mike
authors.initials: M
authors.lastname: Mater
authors.forename: Jun
authors.initials: J
authors.lastname: Ni