| 摘要 |
PURPOSE:To fix a lens frame so that a lens surface is not distorted owing to thermal expansion by providing a stepped or beveled clearance part to the outer peripheral surface of a lens or inner peripheral surface of the lens frame so that an end of the prolongation of one surface of the lens does not abuts on the inner peripheral surface of the lens frame. CONSTITUTION:The lens 10 is arranged in the lens frame and fixed by engaging a pressure ring 13 threadably, and a ring 12 is engaged threadably with the lens frame 11 to press the lens 10 lightly and holds it in this state. Silicone rubber is injected through a silicone rubber injection port 11b to fill a gap A. The silicone rubber solidifies and then the ring 12 is detached from the lens frame, which is fixed by the lens pressure ring 13 and silicone rubber. A step part 10a is provided on the upper end of the prolongation of a lens surface 10 and a beveled part 10c and a projection part 11a are provided on the upper end part of the prolongation of a lens surface 10e. Consequently, the lens surfaces 10d and 10e are prevented from expanding owing the thermal expansion. |
