OBSERVATION OPTICAL SYSTEM AND OBSERVATION DEVICE HAVING THE SAME

摘要

To provide an observation optical system which can be easily reduced in weight and is capable of maintaining good optical performance even amid a change in environment, and to provide an observation device having the same.SOLUTION: An observation optical system comprises an objective optical system, image inversion means for turning an object image formed by the objective optical system into an erect image, and an ocular optical system for magnifying the erect image, and is designed to be used for observing an object image magnified by the ocular optical system. The objective optical system has a resin lens with positive refractive power made of a resin material, and the image inversion means consists of a resin prism made of a resin material. A rate of change in refractive index of the resin material of the resin lens with temperature (dn1/dt) and a rate of change in refractive index of the resin material of the resin prism with temperature (dn2/dt) are appropriately set within a temperature range of 0 to 40°C.SELECTED DRAWING: Figure 1