| 摘要 |
PURPOSE:To precisely and rapidly detect the position of the center of the optical axis by passing a laser beam through an optical path duct filled with a gas capable of easily absorbing laser light, and obtaining the caused gas temp. change from the propagation delay time of an ultrasonic wave. CONSTITUTION:A laser beam 1 is passed through the optical path duct 2 filled with the gas such as the gaseous halogen and CO2 capable of easily absorbing laser light. At this time, the ultrasonic wave emitted from an ultrasonic transmitter 12 is received by a receiver 9, and the propagation delay time of the ultrasonic wave is obtained by the output of an R-S flip flop 13. The position of the center of the optical axis of the beam 1 is obtained from the propagation delay time. By this method, the position is precisely and rapidly detected on a non-contact basis. |
