| Abstrakt: |
Optical fringe patterns characterizing acoustic fields can be photographed by a variety of interferometric, schlieren, and shadow-graphic methods. It is possible to simultaneously determine several independent measures of the acoustic field (such as acoustic pressure and particle velocity) by spatially or temporally differentiating or integrating the optical data since the data are available for an extended region of space and period of time. However, digital processing techniques are required to achieve practical results with the large quantity of data usually involved. In this talk procedures for digitizing, enhancing and compacting data from optical fringe patterns with a solid-state video camera and microprocessor will be demonstrated. Digital image processing approaches which have been implemented on two large computers will be described. Fringe patterns generated from the processed data which correspond to several new measures of acoustic fields will be presented. These techniques will be used to analyze the scattering of sound and shock waves at boundaries. [Research supported by ONR and assisted by Dr. H. Dardy, NRL.] [ABSTRACT FROM AUTHOR] |
