| 摘要 |
<p>The surface of a specimen (2) to be inspected is irradiated with the light of which the intensity varies from a position distant from the material, so that ultrasonic waves are generated in the material to be inspected. A coherent light is also projected onto a fixed surface (8) provided at a given position and onto the surface (40) of said material to be inspected. Vibration generated in the surface (40) of said material (2) due to ultrasonic waves (6b) reflected by defect (7) in the material, is detected in the form of change in phase of the coherent light that is reflected by the surface of the material. The change of difference in phase between the coherent light reflected by said fixed (8) surface and the coherent light reflected by the surface (40) of the material (2) is measured with the lapse of time, in order to detect flaw.</p> |
