A New Liquid-Surface-Relief Method of Acoustic Image Conversion

The liquid-surface-relief method of acoustic image conversion is one of the two earliest methods to be devised for the real-time visualization of ultrasonic images (the other being the electron-beam scanning tube of Sokolov). It is certainly the most easily demonstrated. In the early versions1 demonstrated by Topler and Sokolov, an ultrasonic image field focused onto the liquid surface causes the surface to elevate at each point until equilibrium is established by the restoring forces of surface tension and gravity. The relief pattern formed in this way is an analog of the pattern of acoustic intensity incident at the surface. The deformed fluid surface serves as an optical “phase-object,” and a visible representation of the ultrasonic image is produced by reflecting light from or refracting it through the surface and subsequently forming an image of the deformation pattern, using one of several phase-contrast imaging techniques.