Phase errors in speckle reduced laser fringe projection

S, Rosendahl; E. Hällstig; P. Gren; M. Sjödahl

doi:10.1117/12.869659

13 September 2010 Phase errors in speckle reduced laser fringe projection

S, Rosendahl, E. Hällstig, P. Gren, M. Sjödahl

Proceedings Volume 7387, Speckle 2010: Optical Metrology; 73871E (2010) https://doi.org/10.1117/12.869659
Event: Speckle 2010, 2010, Florianapolis, Brazil

Abstract

When measuring 3D-shape with triangulation and projected interference fringes it is of interest to reduce the phase error in the fringe pattern. A study has been carried out concerning parameters that will affect the phase error and an analytical expression has been derived. It is concluded that the phase error depends on the speckle contrast, C, and the modulation, M, of the fringes and since the phase in this investigation is determined using the spatial carrier method the phase error also depends on the filtering of the Fourier spectrum. To reduce the phase error this work has been focusing on suppressing the speckle contrast. For this the method with a moving aperture is used; a disk with several apertures is rotated in the aperture plane of the camera lens. To verify the derived expression for the phase error and the method to suppress speckles both numerical simulations and experiments have been performed. In the measurements made it was concluded that after an aperture movement of three aperture diameters the speckle contrast and hence the phase error was reduced by 60 %. A phase error of 0.15 radians was obtained in the experiments, thus approximately 1/40 of a fringe period.

Citation Download Citation

S, Rosendahl, E. Hällstig, P. Gren, and M. Sjödahl "Phase errors in speckle reduced laser fringe projection", Proc. SPIE 7387, Speckle 2010: Optical Metrology, 73871E (13 September 2010); https://doi.org/10.1117/12.869659

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