Terry L. Henderson
Appl. Res. Lab., Univ. of Texas at Austin, Austin, TX 78713-8029
The visible portion of a hard-skinned sonar target can be scanned in xyz coordinates by beamforming a planar array, to give a 3-D representation. However, a simple line array running along the x axis can provide a projection view of a target that lies along the z axis, with its upper and lower surfaces being projected semitransparently onto the xz plane, giving a picture analogous to that of a biological specimen viewed with a slide microscope. If the line array is tumbled about the z axis, it will appear that the target is revolving around the z axis. When this tumbling view is presented 14(degrees) out of phase to the left and right eyes, a stereoscopic view of the tumbling target is obtained, with its 3-D form revealed by the brain's innate tomographic signal processing capability. In-water experiments have been conducted for several target shapes. Other means of generating dynamic displays have been developed that are suitable for scanning objects on the seafloor. A videotape of results for several targets has been prepared. Further simplifications of the array structure and processing are possible, with some limitations and weaknesses. [Work supported by ARL:UT IR&D.]