Underwater Acoustical Holographic Imaging by a Square Array System
All the previous theoretical analyses for acoustical holographic imaging are based on the diffraction integral, but most of the underwater man-made objects show mirror reflection character to acoustical waves. Owing to this character, the angular field of view of the imaging system cannot be fully used and the probability of finding an object will be decreased. A new method “multiple sources projection — holograms overlapping — images piecing together method” is presented in this paper. The mathematical expressions also given. A series of experiments were conducted to test the method and study the ability of acoustical holographic imaging for man-made objects using a 64 X 64 square array system. Cylinders of different sizes were used as underwater targets. Results were accorded with theoretical anticipation. The prospect of the system in underwater viewing is also discussed.
KeywordsReconstructed Image Mirror Reflection Object Wave Holographic Imaging Underwater Imaging
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