| 摘要 |
PURPOSE:To provide the title detection device which can detect the focus position of the laser beam of high energy especially with good accuracy by composing so as to project the laser beam passing through a pass and cut means intermittently on an optical detector. CONSTITUTION:In the above detection device the light beam 12 diameter attains to the minimum at its focus F position and the amount passing through the pass and cut means of the light beam 12 to move in the direction along the optical axis of the light beam 12 attains to the maximum at the time when said pass and cut means is located at the focus F position. The light passing thru said pass and cut means is then caught by an optical detector 9 and the position in the moving direction of the pass and cut means at the time is detected by a position detector 2. The focus F position of the light beam 12 is then detected granting that the focus F of the light beam 12 is located at the position equivalent to the detection result of the detector 2 of the time when the light amount caught by said detector 2 attains to the maximum. As a result, the focus position can be detected with good accuracy even in the light beam of high energy without damaging the optical detector by the energy of the light beam. |
