Patent ID: 9028078
Filing Date: 2015-05-12
Classification: G02B

Abstract:
1. A lens apparatus, comprising an optical system comprising a concave lens surface and a convex lens surface adjacent to each other with an air layer therebetween, wherein at least one of the concave lens surface and the convex lens surface comprises an anti-reflection film comprising multiple subwavelength structures at an average pitch of 400 nm or smaller, and wherein the at least one of the concave lens surface and the convex lens surface satisfies the following expressions: provided that: where f represents a focal length of the entire optical system, f 1 represents a focal length of an optical system on an object side with respect to the air layer between the concave lens surface and the convex lens surface, FNo represents an F-number of the entire optical system, h represents an axial conversion beam height on the at least one of the concave lens surface and the convex lens surface having the anti-reflection film formed thereon, R 1 represents a curvature radius of a surface situated on the object side between the concave lens surface and the convex lens surface, and R 2 represents a curvature radius of a surface situated on an image side between the concave lens surface and the convex lens surface.