The Multi-resolution Three-dimensional Digital Imaging Based On Dual Acousto-optic Deflectors

The 3-D sensing is one of the core techniques in 3-D digital imaging and modeling. We are now carrying out a research project supported by National Natural Science Foundation of China grant 60275012, partly supported by the Natural Science Foundation of Guangdong Province (grant 031804), Natural Science Research Grant of Higher Education of Gaungdong province (No. 04Z010) and the Science & Technology Bureau of Shenzhen (grant 200341). The following contributions have been made:1,A three-dimensional profilometry based on a dual-acousto-optic fringe projection is systematically investigated and discussed in this article. In this approach, the first-order beams diffracted from two acousto-optic deflectors (AODs) with each other to form a spatial carrier that is used to encode the depth information from 3-D object surface. A direct digital synthesizer (DDS) is utilized to control two AODs to generate sequentially spatial carriers with different spatial frequencies. The AO technique for producing interference patterns provides significant benefits, such as high precision, full field and dynamic programmable ability.2,A new approach for phase reconstruction based on spatial and temporal phase unwrapping is presented with piece-wise functions by taking both temporal and spatial factors into account during the process of phase reconstruction. This leads to the effective phase reconstruction even under the situation that the number of fringes is not exact the integer exponential of power 2, which is an essential restriction imposed on previous temporal phase unwrapping algorithm. Our approach eliminates the problem of phase ambiguity at the boundaries of phase jump corresponding to the wrapped phase map and therefore provides a more efficient solution to the phase reconstruction of 3D object surfaces with complex geometric and topologic shapes or to a scene with isolated objects.3,By taking advantage of such kind of 3-D imaging system, lots of experiments have been done, especially for some objects with complex geometric and topologic shapes or scenes with isolated objects. The experimental results demonstrate the effectiveness of this 3-D imaging system and the new phase reconstruction approach.