| 摘要 |
PURPOSE:To detect defects on the surface of a sample or just under the surface in a short time in an optoacoustic method by condensing an optical beam to a linear spot on the surface of the sample. CONSTITUTION:A laser optical beam 2 emitted from a laser tube 1 is modulated to an interrupted optical beam by a mechanical chopper 3. This modulated beam 2' is condensed on the surface of a sample 7, which is closed in a sample cell 6 on a stage 10, through a mirror 4 by a cylindrical lens 5. A light-transmissive window 8 consists of, for example, quartz glass. A microphone 9 is buried under the sample 7 in the cell 6. Acoustic waves generated by heat absorption of the modulated optical beam 2' on the surface of the sample 7 are detected by the microphone 9 and are amplified by a lock-in amplifier 11 and are led to a recorder 12. Thus, defects on the surface of the sample 7 or the like are detected in a short time. |
