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US 4,789,219 AGranted
Gradient index retroreflector
AssigneeThe United States of America as represented by the United States Department of Energy
InventorClyde B. Layne
Life of this patent
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Abstract
A retroreflector is formed of a graded index lens with a reflective coating at one end. The lens has a length of an odd multiple of a quarter period thereof. Hexagonally shaped graded index lenses may be closely packed in an array to form a retroreflecting surface.
Claims14
A retroreflective device comprising:
- graded index lens means having opposed first and second planar surfaces,
- said first surface arranged for receiving a beam of irradiation in any arbitrary direction,
- said graded index lens means variably refracting said irradiation transversely during substantially axial passage to said second surface,
- reflecting means covering entirely said second surface for reflecting said refracted irradiation through said lens means to exit said lens means at said first surface in a direction substantially parallel to said arbitrary direction.
1 more element
A retroreflective assembly comprising:
- an array formed of a plurality of graded index lens means, each of said means comprising a gradient index rod with opposed first and second surfaces for receiving rays of electromagnetic radiation at the respective first surfaces thereof in any arbitrary direction relative to a normal of said first surfaces and for variably refracting said rays transversely during substantially axial passage to said second surface thereof,
- reflecting means entirely covering the respective second surfaces for reflecting said rays through said respective lens means substantially axially towards said respective first surfaces to subject said rays to further variable transverse refraction and to cause said rays to exit said lens means at said first surfaces in a direction substantially parallel to said arbitrary direction.
A method of retroreflecting a ray comprising the steps of:
- (a) impinging said ray in any arbitrary direction on a first planar surface of a graded refraction index lens means,
- (b) passing said ray substantially axially through said graded refraction index lens means towards a second planar surface thereof, said second surface being entirely covered by a reflective coating,
- (c) reflecting said ray at said second surface,
- (d) passing said reflected ray substantially axially through said graded refraction index lens means towards said first surface thereof, and
- (e) exiting said ray from said graded refraction index lens means at said first surface in an exit direction substantially parallel to said arbitrary direction.
2 more elements
Dependencies are inferred from the claim text.