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US 4,401,362 AGranted
f-.theta. Lens system
AssigneeOlympus Optical Co., Ltd.
InventorHaruo Maeda
Life of this patent
Estimating the term…
Abstract
An f-.theta. lens system comprising the first lens element which is a positive lens, the second lens element which is a negative lens and the third lens element which is a positive lens. This lens system can be formed as a small lens of a wide angle and has a focusing ability close to the diffraction limit.
Claims6
An f-.theta. lens system consisting of the first lens element which is a positive lens, the second lens element which is a negative lens and the third lens element which is a positive lens and satisfying the following conditions:
- 0.13f.ltoreq.L.ltoreq.0.19f (1)
- 0.9.ltoreq.r.sub.2 /r.sub.3 .ltoreq.1.15 (2)
- -1.65f.ltoreq.f.sub.12 .ltoreq.-0.3f (3)
- wherein the reference symbol f represents a focal length of the entire system, the symbol f.sub.12 represents a composite focal length of the first lens element and second lens element, the symbol L represents an entire length of the lens system and the symbols r.sub.2 and r.sub.3 represent respective radii of curvature of the surface on the light exit side of the first lens element and of the surface on the light entrance side of the second lens element.
1 more element
Dependencies are inferred from the claim text.