LASER ULTRASONIC MEASURING APPARATUS AND LASER ULTRASONIC MEASURING METHOD

摘要

PURPOSE: A laser ultrasonic measuring apparatus and a laser ultrasonic measuring method thereof are provided to facilitate frequency measurement of plate-ultrasonic wave of zero group velocity with high precision. CONSTITUTION: A laser ultrasonic measuring apparatus comprises an irradiation optical system, a detection optical system, an optical detecting unit, and a signal processing unit(60). The irradiation optical system irradiates pulse laser light on test materials. The detection optical system emits continuous wave laser light on the test material. The optical detecting unit receives the light laser and outputs light intensity variation as electric signals. The signal processing unit receives electric signals outputted from the optical detecting unit and draws out the frequency of the plate-ultrasonic wave of the test materials. The signal processing unit comprises a frequency output unit(61) and a phase transformation ratio output unit(65).