The present invention for detecting ultasonic displacements includes a
detection laser to generate a first pulsed laser beam to generate the
ultrasonic surface displacements on a surface of the target. A seocond
pulsed laser beam to detect the ultrasonic surface displacements on a
surface of the target. Collection optics to collect phase modulated light
from the first pulsed laser beam either reflected or scattered by the
target. An interferometer which processes the phase modulated light and
generate at least one output signal. A processor that processes the at
least one output signal to obtain data representative of the ultrasonic
surface displacements at the target.