| 摘要 |
An instrument is described which renders Rayleigh or surface waves visible on a television screen. A flying spot scanner uses a laser beam to scan a substrate horizontally and vertically at standard television rates. The periodic tilting or warping of the surface caused by the passage of an acoustic wave modulates the light reflected from the surface. This modulation is picked up by a photocell, filtered, amplified and heterodyned with a reference signal taken from the sound generator. The resulting difference signal reproduces the surface wave pattern on the television screen, with the waves standing still as if their motion had been arrested by a stroboscope. Normally visible features of the substrate may also be reproduced to serve as background. In a further embodiment, the system is expanded to provide for recording of acoustic holograms. |
