| 摘要 |
PURPOSE:To correct and absorb variation in the refractive index and shape alteration of a plastic lens due to temperature variation and to widen the in-use temperature range of an optical system which uses the plastic lens, by providing the plastic lens with a deformation absorbing member and displacing an adjustment frame by a bimetal. CONSTITUTION:The lens 10 is fixed to the adjustment frame 20, which is fixed to the bimetal 31, so this adjustment frame 20 is moved to a preset focus movement correction position through an adjustment frame flange part 17 by the force of variation in the curvature of the bimetal with temperature; the adjustment frame 20 stops where the optical axis-directional force of the bimetal 31 balances with the force of an elastic body 32, and consequently the air gap between both lenses 10 and 15 is displaced to correct focus movement caused by the variation in the refractive index of the lens 10 with temperature. |
