PROCEEDINGS ARTICLE | February 10, 2005
Proc. SPIE. 5638, Optical Design and Testing II
KEYWORDS: Diffraction, Beam splitters, Fringe analysis, Phase shift keying, CCD cameras, Projection systems, Objectives, Neodymium, Acoustics, Acousto-optics
A three-dimensional (3D) profilometry based on a dual-acousto-optic fringe projection is reported in this paper. The fringe projector is able to generate fringe patterns with different optical sensitivities and therefore can handle the object surface with complex geometry and topology. It is also qualified for video-rate 3-D profilometry of arbitrary shape objects. By using two acousto-optic deflectors (AODs), the projector can generate a time-series, frequency-varying fringe patterns by use of the AO interaction effect. The two AODs are driven by the radio frequency (RF) signal with the same frequency. Changing the RF frequency leads to the change of the period of fringe patterns and, therefore, different sensitivities. In practice, the changing rate of sesitivity is limited by the frame rate of the detector, e.g. CCD, so it makes a dynamic 3-D profilometry possible. Experimentally, we project a sequence of spatial frequency-varying fringe patterns onto the test object surface. Then, a CCD camera simultaneously acquires the phase-modulated fringe patterns accordingly. With a sequence of phase measurement in a progression of fringe periods, an enhanced scheme for phase unwrapping algorithm is implemented in a recursive manner. The object surface with complex geometry and topology can be reconstructed in this way. Experimental results are also given to validate this approach.
