| 摘要 |
An interferometer, that simultaneously employs two phase-quadrature reference beams of coherent light which interfere with a signal beam of coherent light reflected from a spot of a displaceable signal mirror insonified by an ultrasonic wave, permits an output signal to be derived which is proportional to the sum of the squares of the ultrasonic frequency component of the interference between the signal beam and each respective one of the reference beams. This output signal is inherently substantially proportional to the intensity of the ultrasonic wave then insonifying the spot of the signal mirror and independent of random phase drift and environmental vibrations in the interferometer. The interferometric technique of the present invention, which permits the ultrasonic wave to be in the form of pulse bursts of only a few cycles so that the output signal can be range-gated, is suitable for use in an ultrasonic-wave measurement and image display system. |
