The present invention provides a method to detect and generate ultrasonic
displacements at a remote target for ultrasonic inspection. This method
involves generating an ultrasonic wave at a first location on an upper
surface of the remote target. This ultrasonic wave is reflected from
interior surfaces within the remote target wherein the reflected
ultrasonic wave produces ultrasonic displacement at a second location on
the upper surface of the remote target. A detection laser beam is
generated and directed to the second location on the upper surface of the
remote target. Here, the detection laser beam is scattered by the
ultrasonic displacements to produce phase-modulated light. This
phase-modulated light is collected and processed to obtain data
representative of the ultrasonic surface displacements. Further, these
ultrasonic displacements, when processed, will yield inspection
information associated with the interior of the remote target.