title: High-precision three-dimensional shape reconstruction via digital refocusing in multi-wavelength digital holography.
abstract: Three-dimensional (3D) shape reconstructions and metrology measurements are often limited by depth-of-field constraints. Current focus-detection-based techniques are insufficient to profile out-of-focus 3D objects with high axial accuracy. Extended-focus imaging (EFI) techniques can improve the range and precision of such measurements. By incorporating digital refocusing with multiwavelength interferometry, a holographic imaging solution is presented in this paper to accurately measure 3D objects over a large depth range. Accuracy and repeatability of the proposed EFI technique are validated by digital simulations and refocusing experiments. A reconstruction example demonstrates the feasibility of high-precision 3D measurements of objects deeper than the system's classical depth of field.
authors.affiliation: Department of Mechanical Engineering, University of Michigan-Ann Arbor, Ann Arbor, Michigan 48109-2136, USA. xulium@umich.edu
authors.forename: Li
authors.initials: L
authors.lastname: Xu
authors.forename: Carl C
authors.initials: CC
authors.lastname: Aleksoff
authors.forename: Jun
authors.initials: J
authors.lastname: Ni