Fresnel lens array with novel lens element profile

摘要

A Fresnel lens array is provided in which the vertical part of a lens element is replaced by a tilted surface designed to focus impinging light into the focal point of an adjacent lens in the array. Since the new surface forms an angle with the lens plane that is shallower than the vertical step, such a lens element configuration may ease the molding of the lens array in glass type materials. The configuration is not limited to cylindrical arrays, since another array with lens elements perpendicular to the first lens array may be molded on the other side of the lens sheet, resulting in an array of point focusing lenses. Furthermore, by placing mirrors at the edges of the lens array (or at the edge of a single lens thereof) with surfaces perpendicular to the lens plane, the edge light rays may be redirected back to the said focal point(s). In particular, single circular lenses, with lens element cross-sections similar to the one described above and with a vertical mirror at the edge, will also concentrate collimated light to the focal point.

主权项

1. A lens assembly comprising:
a first Fresnel lens comprising a first plurality of circular concentric lens elements, wherein each of said first plurality of circular concentric lens elements has a profile in a plane containing the center point of the lens elements and perpendicular to the plane of the lens elements which includes first and second distinct adjoining portions, wherein either the first or second distinct adjoining portion of each of said first plurality of circular concentric lens elements focuses incident light to one of at least two regions wherein the first portions of the lens elements belong to a first set of lens features and the second portions of the lens elements belong to a second set of lens features wherein the first set of lens features focus light towards a focal point at the optical center of the first Fresnel lens and the second set of lens features focus light radially disposed around the optical center of said first Fresnel lens such that the radially disposed light may be reflected to the focal point at the optical center of the first Fresnel lens by means of an edge mirror.