| 摘要 |
PURPOSE:To hold optical performance without causing a breakdown of a lens due to fluctuations of temperature by using a material which has a coefficient of thermal expansion nearly equal to that of the optical lens of a lens barrel for at least a member which comes into contact with the optical lens. CONSTITUTION:A quartz glass window 2 is provided at the front end part of the outer barrel 1 of a fiber scope, and a holding ring 4 for holding lens groups G1-G4 is fixed in the inner barrel 3 inside of the outer barrel 1 at a prescribed air interval. FUrther, an end surface S of an image fiber 5 is stuck to the inner barrel 3 behind the holding ring coaxially with the optial axis l through a fitting ring. The lens groups G1-G4 are fixed through the holding ring 4, interval rings 7-9, and retaining ring 10, and those members are made of materials having coefficients of thermal expansion nearly equal to those of the lens groups G1- G4. Therefore, none of the lens groups G1-G4 breaks down owing to fluctuations of temperature, and the optical performance is maintained. |
