Satoshi Ogura

Development of an ultrasonic inspection system using array transducers

Abstract A new ultrasonic inspection system was developed to obtain ultrasonic images of defects. This system adopts an electronic beam control method using array transducers. The beam control modes are a compound scanning mode and a linear scanning mode. Both modes are performed by timing control of ultrasonic wave transmission and reception at each transducer element. In the focal beam, the refraction of the ultrasonic wave at the boundary between water and metal in immersion testing is utilized to improve the lateral resolution of the ultrasonic beam. In steel, the improvement is a maximum of 25% for focal lengths from 5 to 35 mm as compared to lateral resolution not utilizing refraction. This system successfully imaged two side drilled holes in a steel block.

Output power stabilization of a XeCl excimer laser by HCl gas injection

A laser output power control system which has an ability to realize high stability of the laser output power in long-term operation is proposed for high-power rare-gas halide excimer lasers. The system has a function of maintaining laser gas conditions, mainly the halogen gas concentration, constant against the gas degradation in the laser tube. As a result the laser output power is stabilized at near maximum available power. The system has been applied to a 20-W UV-preionozed XeCl excimer laser and the laser output power has been stabilized for 8 hours successfully with a fluctuation less than +/- 2% at 20 W.