FRESNEL LENS WITH REDUCED DRAFT FACET VISIBILITY

摘要

A curved Fresnel lens is provided. The Fresnel lens includes a grooved surface and a smooth surface. The grooved surface includes a plurality of concentric sloped facets and a plurality of concentric draft facets. Pairs of concentric draft facets and concentric sloped facets form a plurality of concentric grooves in the grooved surface. The concentric sloped facets are configured to focus light toward an eye of a nominal user. At least some of the concentric draft facets are congruent with conical surfaces of respective imaginary light cones that have corresponding vertices that originate from respective focal points, wherein each imaginary light cone extends through the Fresnel lens at an angle based in part on an index of refraction of the Fresnel lens and extends beyond the grooved surface into free space.

主权项

1. A curved Fresnel lens comprising:
a grooved surface and a smooth surface, the grooved surface comprising a plurality of concentric sloped facets and a plurality of concentric draft facets, pairs of concentric draft facets and concentric sloped facets forming a plurality of concentric grooves in the grooved surface, the plurality of concentric sloped facets configured to focus light toward an eye of a nominal user; at least some of the plurality of concentric draft facets being congruent with conical surfaces of respective imaginary light cones that have corresponding vertices that originate from respective focal points, wherein each respective imaginary light cone extends through the Fresnel lens at an angle based in part on an index of refraction of the Fresnel lens and extends beyond the grooved surface into free space.