Westerman, Hattori, Daniels & Adrian, LLP
Imaging lens
A concave surface is formed on an object side of a plastic lens of a one-piece construction, and a convex surface is formed on an image-point side thereof. The concave and convex surfaces are aspherical. A diffractive optical surface that exerts a chromatic dispersion ability is formed on the convex surface, and conditional expressions (1) 0.45<L/R<0.95 and (2) −0.065<L′(1−n)/R′<0.035n are met, where assuming that a position at which a chief ray and an optical axis intersect is regarded as an apparent stop, L denotes a distance to the apparent stop seen from the apex of the convex surface, L′ denotes a distance to the apparent stop seen from the apex of the concave surface, R denotes a curvature radius of the convex surface, R′ denotes a curvature radius of the concave surface, and n denotes a refractive index of a lens material.
Kantatsu Co., Ltd.
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Shingo Hisanori Kazuo Ichiro
Watanabe Suzuki Matsuoka Kurihara