Patent ID: 9574738
Date: 2017-02-21
CPC Classifications: F21V,G02B

Claim:
1. A lens comprising: a light incident surface configured to receive light emitted from a light emitting element; and a light output surface opposite to the light incident surface and configured to radiate the light received from the light emitting element; wherein in a coordinate system, the light incident surface satisfies a formula (1): c 1 is a curvature of the light incident surface, r 1 is a distance from the center of the lens to a joint point between the light input surface and a radius which is substantially perpendicular to the central axis of the lens, u 1 is a normalized radius of the light incident surface, a m represents the aspheric coefficient, Q m is a polynomial of order m and represents that the sum of a m is equal to the sum of the root mean square of the slope of the light incident surface; wherein the light output surface satisfies a formula (2): c 2 is a curvature of the light output surface, r 2 is a distance from the center of the lens to a joint point between the light output surface and a radius which is substantially perpendicular to the central axis OO′, u 2 is a normalized radius of the light output surface, a m represents the aspheric coefficient, and Q m is a polynomial of order m and represents that the sum of a m is equal to the sum of the root mean square of the slope of the light output surface.