| 摘要 |
PROBLEM TO BE SOLVED: To obtain excellent visibility by constituting an ocular of two lenses being a single lens and making the two lenses have appropriate shape satisfying a specified conditional expression. SOLUTION: The ocular is constituted of a roof mirror 5 having reflection surfaces orthogonal to each other and reflecting emitted light from the emitting surface 4d of a prism 4 on the respective reflection surfaces so as to reverse the right and the left of an image and guiding the reflected light downward or lower obliquely backward, a 1st lens 6 having positive refractive power, a plane reflection mirror 7 reflecting a light beam reflected by the mirror 5 and guided through the lens part 6 backward (observation side), and a 2nd lens part 8 having negative refractive power. When the radii of curvature of the lens surfaces of the lens part 6 on a focusing screen side and on an observation side are respectively defined as R1a and R1b, and the radii of curvature of the lens surfaces of the lens part 8 on the focusing screen side and on the observation side are respectively defined as R2a and R2b, the condition shown by the expression is satisfied.
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