Fresnel lens with aspheric grooves

• US RE35,534 E
• Filed: 04/15/1994
• Issued: 06/17/1997
• Est. Priority Date: 04/10/1986
• Status: Expired due to Term

• Current Assignee: Fresnel Technologies Incorporated (Fresnel Tech Incorporated)
• Original Assignee: Fresnel Technologies Incorporated (Fresnel Tech Incorporated)
• Inventors: Claytor, Richard N.
• Primary Examiner(s): Sugarman, Scott J.
• Application Number:
  US08/228,115
• Time in Patent Office: 1,159 Days
• Field of Search: 359/742, 359/743, 359/708
• US Class Current: 359/742
• CPC Class Codes: G02B 3/08 with discontinuous faces, e.g. Fresnel lens diffractive Fresnel lenses G02B5/1876

Abstract

A Fresnel lens formed of an infrared transmitting material has a grooved surface. The grooves all extend to the same depth, and the distances between successive grooves vary across the lens. In a circular lens, the grooves are concentric, and the distances between grooves nearer the center are longer than the distances between the grooves nearer the circumference. A substantial portion of the grooves have an aspherical surface.

Claims

1. A Fresnel lens formed of a material capable of transmitting infrared energy rays, .Iadd.in the wavelength range from 8 to 14 micrometers, .Iaddend.the lens comprising:

a body, having a grooves surface;

the grooves surface having a plurality of grooves, which extend to the same depth;

the grooves being of different widths; and

a substantial portion of the grooves each individually having a surface formed thereon which is entirely aspherical and differs in contour from the surfaces of the other grooves.

2. A Fresnel lens formed of a material capable of transmitting infrared energy rays, .Iadd.in the wavelength range from 8 to 14 micrometers, .Iaddend.the lens comprising:

a body, having a substantially flat grooved surface;

the grooved surface having a plurality of grooves, each of which extend to the same depth;

the grooves being of different widths; and

a substantial portion of the grooves each individually having a surface formed thereon which is entirely aspherical and differs in contour from the surfaces of the other grooves. .Iadd.3. The Fresnel lens according to claim 1 wherein the material of the lens is a plastic. .Iaddend..Iadd.4. The Fresnel lens according to claim 1 wherein the material of the lens is

3. polyethylene. .Iaddend..Iadd.5. A Fresnel lens, comprising in combination:

A body formed of a polyethylene material capable of transmitting infrared energy rays in the wavelength range from 8 to 14 micrometers, the body having a grooved surface;

the grooved surface having a plurality of grooves which extend to the same depth;

the grooves being of different widths; and

a substantial portion of the grooves each individually having a surface formed thereon which is entirely aspherical and differs in contour from the surface of the other grooves. .Iaddend.