| 摘要 |
PURPOSE:To obtain a compact and bright reflecting and refracting lens with a wide angle of fields by arranging a submirror equipped with a back reflecting surface in the object side, a positive lens, a positive lens, a main mirror, and a negative lens group in order from the object side and satisfying prescribed conditions. CONSTITUTION:A lens L1 turning its convex side toward the object side, a main mirror M1 equipped with a refracting surface and a back reflecting surface both of which turning their concave sides toward the object side respectively, a positive lens L2 cemented with the central part of L1 in the image side and turning its convex side toward the image side, a submirror M2 with both concave sides which is cemented with the central part of L1 in the object side and equipped with a back reflecting surface in the object side, and a negative lens group located near the central opening part of the M1 are arranged and the conditions of formulas (1)-(8) are satisfied. Where, TL is the axial length from the reflector of M2 to the surface of an image, TD is the axial length from the reflector of M2 to the final refracting surface, R1-R6 are curvature radiuses of refracting surfaces or reflecting surfaces arranged successively from the object side, fm is a composite focal distance of L1, L2 and M2, and fk and f are focal distances of the negative lens group and the whole system. Thus, a compact and bright reflecting and dioptric lens with a wide angle of fields can be obtained. |
