Stroboscopic Holography for Measuring Mutual Coupling in Sonar Arrays.

摘要

Mutual coupling between elements of active sonar transducer arrays operating under water have not been accurately predicted by array interaction computer programs in the past. Until the advent of holography, there was no feasible way to experimentally measure mutual coupling. This report summarizes the development and field testing of a stroboscopic holographic system that measures the displacement and the phase of the elements in small sonar arrays. These data are derived by using time-average and stroboscopic holograms. The final field testing was performed on two small arrays located at a depth of 100 ft in a 50-ft-diameter steel tank at the Naval Ordnance Laboratory (NOL), Silver Spring, Maryland. Ungated and gated holograms were made to eliminate acoustic reflections from the tank walls.