| 摘要 |
A lens comprises an incident curved surface and an exit curved surface opposite to the incident curved surface. The incident curved surface and the exit curved surface are configured such that light emitted from a light emitting diode (LED) light source enters the lens through the incident curved surface and incident on the exit curved surface, and is refracted by the exit curved surface. The position of a point on the exit curved surface is represented by z=z0−√{square root over (r2−(x2+y2))}+ax2+by2+cx2y2, where x, y and z are respective coordinates along X, Y and Z axes, and parameters a, b, c, r and z0 are numbers determining the shape of the exit curved surface. The Z axis coincides with an optical axis of the lens. |
