Acoustic Bubble Detection: Acoustic-Optical Imaging Techniques for Decompression Studies.

Abstract : The acoustic-optical imaging process utilizes Bragg diffraction of light by a beam of sound to produce an optical image of an acoustically irradiated object. Inasmuch as many materials which are quite opaque to light are, to varying degrees, transparent to certain acoustic frequencies, the technique offers the possibility of visually examining the internal structure of optically opaque bodies. The imaging of internal features is made possible by the fact that different materials and structures often have different acoustic characteristics, thus causing the sound to be reflected, scattered, absorbed and diffracted. These factors cause perturbations in the acoustic wavefronts which are transformed in the light-sound interaction into a visual image, in real time, which may be observed by eye, photographed by a camera, or processed by other conventional optical methods. In addition to bubble detection, acoustic-optical imaging techniques appear to be applicable to a wide range of diagnostic procedures and methods of medical instrumentation where the ability to observe internal structures is of significance. (Author)