Non-orthogonal cube corner elements and arrays thereof made by end milling
Assignee3M Innovative Properties Company
InventorsNelson D. SEWALL, Christopher S. GRINDE, Todd A. BALLEN, Kenneth L. SMITH
Life of this patent
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Abstract
A new technique for making cube corner elements that involves end milling is used in the fabrication of cube corner elements having non-orthogonal dihedral angles and dihedral angle errors, and arrays of such cube corner elements. A given optical face of a cube corner element may be a compound face with two constituent faces. In some cases, the constituent faces may be parallel and coplanar such that a given dihedral angle error pertains to the entire optical face, while in other cases, the two constituent faces may not be parallel, and may be associated with different dihedral angle errors.
Claims22
An article comprising a structured surface that extends along a reference plane, the structured surface comprising a first cube corner element and remaining cube corner elements, the first cube corner element having a first, second, and third optical face;
- wherein at least part of the first optical face deviates from orthogonality relative to at least a part of the second optical face by a first angle error whose magnitude is at least 1 minute of arc but no more than 2 degrees;
- and
- wherein the at least part of the first optical face is not coplanar with any optical face, or portion thereof, of any of the remaining cube corner elements that are adjacent to the first cube corner element.
An article comprising a cube corner element defined in a structured surface, the structured surface extending along a reference plane, the cube corner element including a first rounded edge that is inclined relative to the reference plane, the cube corner element also including a first, second, and third optical face, wherein at least part of the first optical face deviates from orthogonality relative to at least part of the second optical face by a first angle error whose magnitude is at least 1 minute of arc but no more than 2 degrees.
14-16. (canceled)
21-32. (canceled)
A method of making a cube corner element, comprising:
- providing a substrate;
- cutting the substrate with a first rotating end mill to form a recess in the substrate, the first recess having a first face;
- and
- further cutting the substrate with a second rotating end mill to enlarge the recess and to form a second face, the second rotating end mill optionally being identical to the first rotating end mill;
- wherein the first and second faces form a compound face of the enlarged recess, the compound face being a first optical face of the cube corner element, the cube corner element also having a second and third optical face;
- and
- wherein the first face deviates from orthogonality relative to at least part of the second optical face by an angle error whose magnitude is at least 1 minute of arc but no more than 2 degrees.
A method of making a cube corner element in a substrate that extends along a reference plane, the method comprising cutting the substrate with at least one rotating end mill along at least one cutting path that is inclined relative to the reference plane, the cutting being carried out such that a first part of a first optical face of the cube corner element deviates from orthogonality relative to a first part of a second optical face of the cube corner element by an angle error whose magnitude is at least 1 minute of arc but no more than 2 degrees.
A method of making a cube corner element in a substrate, comprising forming part of a first optical face of the cube corner element by cutting the substrate with a rotating end mill, the forming being carried out such that the part of the first optical face deviates from orthogonality relative to at least part of a second optical face of the cube corner element by an angle error whose magnitude is at least 1 minute of arc but no more than 2 degrees.
Dependencies are inferred from the claim text.