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Patent Searching and Data

Document Type and Number:
Japanese Patent JP3427461
Kind Code:

PURPOSE: To obtain the image re-formation optical system which has superior optical performance although the overall length is short and the constitution is relatively simple by providing a front and a rear group which are composed of 1st-3rd lens groups and specifying their lens elements.
CONSTITUTION: Light from a primary image I1 formed in the front group G1 is passed through the front group G1 and rear group G2 to form a secondary image I2 which is specific times as large as the primary image In. The front group G1 consists of a plano-convex positive lens element L1 which is convex to an objective optical system, a biconcave negative lens element L2 which has a large-curvature concave surface on the side of the secondary image I2, and a biconvex positive lens element L3 which has a large-curvature convex surface on the side of the secondary image I2. The rear group G2 has the cemented lens element composed of a meniscus negative lens element L4 and a biconvex positive lens element L5 and a biconvex positive lens element L6. Thus, the front group G1 has the positive, negative, positive refracting power arrangement, so the front principal point of the front group G1 is positioned on the side of the secondary image I2 and the rear principal point is positioned on the object optical system side. Consequently, the overall length of the group G1 can be shortened.

Ouchi, Yumiko
Application Number:
Publication Date:
May 16, 2003
Filing Date:
February 18, 1994
Export Citation:
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International Classes:
G02B9/60; G02B25/00; (IPC1-7): G02B9/60