Document Type
Patent
Publication Date
October 2004
Patent Number
6809845
Abstract
The present invention is a phase-imaging technique by digital holography that eliminates the problem of 2π-ambiguity. The technique is based on a combination of two or more digital holograms generated using multiple wavelengths. For a two-wavelength experiment, the phase maps of two digital holograms of different wavelengths are subtracted which yields another phase map whose effective wavelength is inversely proportional to the difference of wavelengths. Using two holograms made with a 633 nm HeNe laser and a 532 nm doubled YAG laser an image was obtained that is a 3D reconstruction of a reflective surface with axial resolution of ˜10 nm over a range of −5 um, without any phase discontinuity over this range. The method can be extended to three wavelengths or more in order to reduce the effect of phase noise further.
Application Number
10/668,080
Recommended Citation
Kim, Myung K.; Gass, James; and Dakoff, Aaron, "Phase imaging using multi-wavelength digital holography" (2004). USF Patents. 767.
https://digitalcommons.usf.edu/usf_patents/767
Assignees
University of South Florida
Filing Date
09/22/2003
Primary/U.S. Class
359/9
