| 摘要 |
PURPOSE:To improve the positioning precision of a relay lens group by positioning and adjusting a focal point by the optical-axis movement of a compensating lens group. CONSTITUTION:An eccentric pin 37 has a screw part 37 eccentrically with a head part 37a, and the screw part 37b engages the screw hole 36a of a holding frame 36 threadably to allow the head part 37a to rotate. The head part 37a is fitted in a specifying long hole 35c bored in a cam frame 35 in a circumferential direction. When the focal point is positioned and adjusted, the eccentric pin 37 is rotated to displace the head part 37a to or from the screw part 37b. The head part 37a is displaced to or from the cam frame 35 in optical-axis directions while a support frame 36 is guided by a guide long hole 5b and a guide pin 38. The rotation of the eccentric pin 37 is stopped once the focal point is positioned at a specified position over a look at a collimator. The position relation between a variable power lens group II and the compensating lens group III is determined unequivocally and the focal point is positioned and adjusted accurately. |
