Patent ID: 6813951
Filing Date: 2004-11-09
Classification: G01N

Abstract:
A method for ultrasonic testing of objects comprising:generating ultrasound inside or at the surface of the object; providing a long-pulse laser oscillator for generating an incident beam and comprising a resonant cavity containing a lasing medium; strongly pumping said lasing medium for a sufficient period of time to generate a laser pulse that during an initial period has a strongly fluctuating intensity and during a subsequent quieter period has an intensity with substantially reduced fluctuations; illuminating the surface of the object with said incident beam; collecting light from said incident beam that is scattered or reflected by the surface of the object; demodulating the light scattered or reflected during said subsequent period of said laser pulse; with a frequency tracking demodulator to obtain a signal beam; and detecting said signal beam with a differential detector to compensate for residual intensity fluctuations and obtain a signal representative of the ultrasonic motion.