Patent ID: 8941932
Filing Date: 2015-01-27
Classification: G02B

Abstract:
1. A Fresnel lens comprising an incident surface that is flat, and a prism-forming surface that has a plurality of prisms, the prism-forming surface being provided on a side of the Fresnel lens opposite to the incident surface, wherein: each of the prisms has a converging surface that is located on a side away from an optical axis of the Fresnel lens; when a distance away from the optical axis in a radial direction of the Fresnel lens is defined as r, and predetermined values R1, R2, and R3 in the radial direction are set so as to satisfy R1<R2<R3, in a range of 0≦r<R1, a relationship θ in a range of R1≦r<R2, a relationship f(R1)≦θ where θ