| 摘要 |
PROBLEM TO BE SOLVED: To dispense with highly accurate adjustment inevitable to an interferometer and to enable even an unskilled person to easily handle an apparatus. SOLUTION: The laser beam 151 emitted from a laser beam source 11 is incident on the surface of an object 30 to be inspected at a predetermined angle θand reflected by the mirror surface of the specimen 30 at the angle equal to the incident angle to become reflected beam 152 . The reflected beam 152 is applied to the surface of a PSD 12 to be converted to an electrical signal and, when ultrasonic waves propagate along the surface of the specimen, the surface of the specimen is displaced and the normal line direction of the surface thereof a changed. Herein, if the beam diameter of laser beam 151 is made sufficiently smaller than the wavelength λ of ultrasonic waves propagation along the surface of the specimen, even if the incident beam 151 is incident on the same point, the incident angle and reflected angle thereof change and the reflecting direction of the reflected beam 152 changes and, therefore, ultrasonic waves can be detected as a change of the position of the spot on the PSD. |
