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Proceedings Paper

New PMP method with two-frequency grating projection
Author(s): Jie-lin Li
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Paper Abstract

In phase-shift phase-measuring profilometry [1,2], an equivalent wavelength of the system could be defined as = P where p0 is the mean fringe pattern period at the reference plane, and e is the angle between the P. 0 direction of projection and the direction of observation. Increasing of equivalent wavelength leads to slowing down of the fringe phase variation. It would be benefit to phase unwrapping , but in the same time it leads to lower measurement accuracy. Here we present a new method. Considering both the reliability of phase unwrapping and the measurement accuracy of the system, we make two sets of fringes with different frequencies on a single grating pattern. Instead of using N (N=3,4,5 ...) phase steps, 2N phase steps is used. The phases of the two frequencies are calculated separately. It's possible to unwrap the high frequency phase, with reference to the low frequency phase.

Paper Details

Date Published: 1 September 1996
PDF: 2 pages
Proc. SPIE 2778, 17th Congress of the International Commission for Optics: Optics for Science and New Technology, 27786G (1 September 1996); doi: 10.1117/12.2299115
Show Author Affiliations
Jie-lin Li, Sichuan Union Univ. (China)


Published in SPIE Proceedings Vol. 2778:
17th Congress of the International Commission for Optics: Optics for Science and New Technology
Joon-Sung Chang; Jai-Hyung Lee; ChangHee Nam, Editor(s)

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