APPARATUS FOR MEASURING THRESHOLD VALUE OF LASER DAMAGE

摘要

PURPOSE:To improve reliability in measurement and to simplify the measurement by detecting the scattered light of emitted laser light from a damaged part. CONSTITUTION:When the intensity of emitted laser light 2 at the position of a sample 6 exceeds a certain value (damage threshold value), a laser damaged part 11 is formed in a sample 6. The laser light 2 is scattered from the damaged part 11. The scattered from the damaged part 11. The scattered light which is a part of the scattering laser light is detected with a photodetector 13. Thus, the degree of the laser damage is measured. As the photodetector 13, a photodiode, a highly planar phototube or the like is used. When the light-source laser device of the laser light 2 is operated in a pulse mode, the peak value of the signal is detected with a storage oscilloscope, a peak detecting circuit or the like in a signal processing circuit 14. In a continuous transmitting operation, a lock-in amplifier or the like is used. Since the scattered light 12 which is increased approximately proportionally with the occurring degree of the damages is detected in this way, the measurement can be performed simply and high sensitively at the initial stage of the damage.