Retroreflective surface

Claim 2

A retroreflector constructed so that diffraction is a dominant factor governing the angular divergence of retroreflected light from perfect retroreflection, said retroreflector consisting essentially of a hexagonal close packed array of contiguous cube corners having windows which are equilateral triangles defined at the intersecting boundaries of respective contiguous cube corners in said array by three sets of continuous parallel lines all oriented in a plane with included angles of 60* between respective lines of each such set at a common point of intersection, said cube corners each having three adjacent faces intersecting at dihedral angles of 90* + OR 2.8 minutes of arc, the respective adjacent lines in each such three sets of parallel boundary lines being all equally spaced apart with normal spacing in the range from 15.5 to 830 microns between adjacent lines of each set, said normal spacing of parallel lines being a value within the defined range selected to produce a desired angular divergence of the retroreflected light due to diffraction, and the faces of said cube corners all being essentially specular mirror surfaces having reflective coefficients of at least 0.6.

Claim 3

A retroreflector defined by claim 1 wherein the defined array of cube corners is defined as cavities in the surface of a thin sheet of plastic resin material.

Claim 4

A retroreflector defined by claim 1 wherein the defined array of cube corners is defined as cavities in a metal surface.

Claim 5

A retroreflector defined by claim 1 wherein the defined array of cube corners are cavities filled with optically transparent solid material.

Claim 6

A retroreflector defined by claim 1 wherein the defined array of cube corners consists of transparent cube corner prisms formed in and projecting from the back of a sheet of transparent sheet material.

Claim 7

A retroreflector defined by claim 5 having the faces of the defined prisms in contact with air and the prisms being retroreflective by total internal reflection.

Claim 8

A retroreflector defined by claim 5 having the outer prism surfaces coated with evaporated metal mirror coating and a protective covering.

Claim 9

A retroreflector defined by claim 1 wherein the defined normal spacing between parallel boundary lines is about 254 microns.

Claim 10

A retroreflector defined by claim 1 wherein the defined specular reflective coefficient of each mirror surface is about 0.9.

Claim 11

A retroreflector defined by claim 1 wherein each cube corner face in the array is cylindrically concave outward between base and apex with radius of curvature less than 400 feet.

Claim 12

A retRoreflector defined by claim 10 wherein the defined radius of curvature is about 200 feet.

Claim 13

A retroreflector defined by claim 3 wherein the front surface of plastic material through which incident and retroreflected light are transmitted and refracted, forms a spherical convex lens surface having radius of curvature less than 400 feet.

Claim 14

A retroreflector defined by claim 12 wherein the defined radius of curvature is about 200 feet.

Claim 15

A retroreflector constructed so that diffraction is a dominant factor governing the angular divergence of retroreflected light from perfect retroreflection, said retroreflector consisting essentially of a hexagonal close packed array of contiguous cube corners having windows which are equilateral triangles defined at the intersecting boundaries of respective contiguous cube corners in said array by three sets of continuous parallel lines all oriented in a plane with included angles of 60* between respective lines of each such set at a common point of intersection, said cube corners each having three adjacent faces intersecting at dihedral angles two of which are 90* + or - 2.8 minutes of arc and the other is 90* + or - 2*, the respective adjacent lines in each such three sets of parallel boundary lines being all equally spaced apart with normal spacing in the range from 3.5 to 250 microns between adjacent lines of each set, said normal spacing of parallel lines being a value within the defined range selected to produce a desired angular divergence of the retroreflected light due to diffraction, and the faces of said cube corners all being essentially specular mirror surfaces having reflective coefficients of at least 0.6.

Claim 16

A retroreflector constructed so that diffraction is a dominant factor governing the angular divergence of retroreflected light from perfect retroreflection, said retroreflector consisting essentially of a hexagonal close packed array of contiguous cube corners having windows which are equilateral triangles defined at the intersecting boundaries of respective contiguous cube corners in said array by three sets of continuous parallel lines all oriented in a plane with included angles of 60* between respective lines of each such set at a common point of intersection, said cube corners each having three adjacent faces intersecting at dihedral angles two of which are 90* + or - 2.8 minutes of arc and the other is 90* + or - 2*, the respective adjacent lines in each such three sets of parallel boundary lines being all equally spaced apart with normal spacing in the range from 3.5 to 250 microns between adjacent lines of each set, said normal spacing of parallel lines being a value within the defined range selected to produce a desired angular divergence of the retroreflected light due to diffraction, and the faces of said cube corners all being essentially specular mirror surfaces having reflective coefficients of at least 0.6.

Claim 17

A retroreflector constructed so that diffraction is a dominant factor governing the angular divergence of retroreflected light from perfect retroreflection, said retroreflector consisting essentially of a hexagonal close packed array of contiguous cube corners having windows which are equilateral triangles defined at the intersecting boundaries of respective contiguous cube corners in said array by three sets of continuous parallel lines all oriented in a plane with included angles of 60* between respective lines of each such set at a common point of intersection, said cube corners each having three adjacent faces intersecting at dihedral angles one of which is 90* + or - 2.8 minutes of arc and the other two are 90* + or -2.0*, the respective adjacent lines in each such three sets of parallel boundary lines being all equally spaced apart with normal spacing in the range from 3.5 to 250 microns between adjacent lines of each set, said normal spacing of parallel lines being a value within the defined range selected to produce a desired angular divergence of the retroreflected light due to diffraction, and the faces of said cube corners all being essentially specular mirror surfaces having reflective coefficients of at least 0.6.

Claim 18

A retroreflector constructed so that diffraction is a dominant factor governing the angular divergence of retroreflected light from perfect retroreflection, said retroreflector consisting essentially of a hexagonal close packed array of contiguous cube corners having windows which are equilateral triangles defined at the intersecting boundaries of respective contiguous cube corners in said array by three sets of continuous parallel lines all oriented in a plane with included angles of 60* between respective lines of each such set at a common point of intersection, said cube corners each having three adjacent faces intersecting at dihedral angles one of which is 90* + or - 2.8 minutes of arc and the other two are 90* + or -2.0*, the respective adjacent lines in each such three sets of parallel boundary lines being all equally spaced apart with normal spacing in the range from 3.5 to 250 microns between adjacent lines of each set, said normal spacing of parallel lines being a value within the defined range selected to produce a desired angular divergence of the retroreflected light due to diffraction, and the faces of said cube corners all being essentially specular mirror surfaces having reflective coefficients of at least 0.6.

Claim 19

A retroreflector constructed so that diffraction is a dominant factor governing the angular divergence of retroreflected light from perfect retroreflection, said retroreflector consisting essentially of a hexagonal close packed array of contiguous cube corners having windows which are equilateral triangles defined at the intersecting boundaries of respective contiguous cube corners in said array by three sets of continuous parallel lines all oriented in a plane with included angles of 60* between respective lines of each such set at a common point of intersection, said cube corners each having three adjacent faces intersecting at dihedral angles of 90* + or -2*, the respective adjacent lines in each such three sets of parallel boundary lines being all equally spaced apart with normal spacing in the range from 3.5 to 250 microns between adjacent lines of each set, said normal spacing of parallel lines being a value within the defiNed range selected to produce a desired angular divergence of the retroreflected light due to diffraction, and the faces of said cube corners all being essentially specular mirror surfaces having reflective coefficients of at least 0.6.

Claim 20

A retroreflector constructed so that diffraction is a dominant factor governing the angular divergence of retroreflected light from perfect retroreflection, said retroreflector consisting essentially of a hexagonal close packed array of contiguous cube corners having windows which are equilateral triangles defined at the intersecting boundaries of respective contiguous cube corners in said array by three sets of continuous parallel lines all oriented in a plane with included angles of 60* between respective lines of each such set at a common point of intersection, said cube corners each having three adjacent faces intersecting at dihedral angles of 90* + or -2*, the respective adjacent lines in each such three sets of parallel boundary lines being all equally spaced apart with normal spacing in the range from 3.5 to 250 microns between adjacent lines of each set, said normal spacing of parallel lines being a value within the defiNed range selected to produce a desired angular divergence of the retroreflected light due to diffraction, and the faces of said cube corners all being essentially specular mirror surfaces having reflective coefficients of at least 0.6.