| 摘要 |
PROBLEM TO BE SOLVED: To evaluate an objective material over a wide range by intersecting a plurality of energy beams having different frequencies on a specimen to cause interference, detecting a bulk ultrasonic wave produced by scanning interference fringes using a probe light on the specimen without touching the specimen, and then moving the inspection point through relative scanning of the specimen, beam and probe light. SOLUTION: Laser light from a laser light source 13 is split into beams B1, B2 and the beam B1 is subjected to frequency shift through an acoustooptic system 7 and intersected with the beam B2 to cause interference on the surface of a sample 12 thus forming scanning interference fringes. Consequently, a bulk ultrasonic wave is excited in the sample 12 and reflected and diffracted by an internal flaw before appearing on the surface of sample 12. Laser light from laser light source 13 is condensed through an optical system 14 to form a spot on the sample 12 and a reflected light is condensed through an optical system 15 and detected by a photodetector 17 thus detecting deformation on the surface of sample 12. The waveform is inputted to an oscilloscope 21 along with one passed through a BPF 18 and analyzed. The detection point is shifted by scanning any one of the sample 12, beam B1, B2, or spot. |
