| 摘要 |
PURPOSE:To contrive miniaturization and light weight and to simplify the constitution of an eyepiece by allowing a prism group to have not only a roof surface but also two reflection planes and constituting them so that optical paths do not intersect. CONSTITUTION:A prism group 14 including a roof surface 11 consists of a roof prism 10 and a triangular prism 13, and light is reflected on the roof surface 11, a plane 15, and a plane 6 in order from the object side. Positional relations among respective reflection surfaces are so determined that light is made incident on reflection surfaces from opposite sides, namely, the lift, the right, and the left of normals of respective reflection surfaces, and optical paths do not intersect in the prism group 14 including the roof surface 11. An angle theta of incidence of light on the roof edge is set to the range of 15 deg.-45 deg. to shorten the optical path length required for reflection on the roof surface. Thus, the roof prism part itself is made small-sized and light-weight and the lens constitution of the eyepiece is simplified.
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