Asymmetric TIR lenses producing off-axis beams
The present invention relates to an improvement of a total internal reflection lens whereby a tilted symmetry axis leads to a net deflection of the output beam away from the surface normal of the exit surface. Linear TIR lenses have a net deflection transverse to their focal strip. Circular TIR lens profiles going beyond 90° are tilted to bring the rim level with the source, the deflected rays exiting the lens to form an off-axis beam.
1. A tilted-beam illumination lens system, comprising:
a smooth upper surface; and
a lower surface comprising a plurality of deflective facets deployed asymmetrically about an axis tilted from the surface normal of said upper surface, said lower-surface facets receiving light from a common focal zone and forming a beam therefrom, said beam propagating upward within the body of said lens along said tilted axis, said beam exiting said upper surface with a net deflection angle relative to said surface normal of said smooth upper surface, said deflective facets comprising both refractive and totally internally reflecting facets.
2. The system of claim 1 wherein said deflection angle is 30° or more.
3. The system of claim 1 wherein positioned within said focal zone are one or more light-emitting diodes.
4. The system of claim 1 wherein said system is for use on a vehicle.
5. The system of claim 1 wherein said smooth upper surface has curvature conformal with that of the surface onto which said system is installed, and said deflective-facets act to counter said curvature to produce substantially parallel rays exiting said upper surface.
6. The system of claim 1 wherein said deflective facets are linear grooves with transverse deflection, and said focal zone is a linear strip.
7. The system of claim 6 wherein said transverse deflection of said plurality of longitudinal facets is the same on both sides of said focal zone.
8. The system of claim 6 wherein said focal strip bears a multiplicity of point sources.
9. The system of claim 8 wherein said external surface comprises a plurality of transverse cylindrical lenses in correspondence with said point sources.
10. The system of claim 9 wherein each of said transverse cylindrical lenses comprises multiple radii of curvature.
11. The system of claim 1 wherein said deflective facets are circular grooves with a central focal zone and a tilted axis of rotational symmetry.
12. The system of claim 11 wherein said circular grooves comprise a TIR lens with rim angle greater than 90°, said tilted axis bringing said rim angle level with said focal zone.
13. A tilted-beam illumination lens, comprising:
a smooth upper surface; and
a lower surface having a first half and a second half, wherein said first half is a converging TIR lens and said second half is a diverging TIR lens, said converging TIR lens and said diverging TIR lens having a plurality of deflective facets, each of said facets having the same output angle such that said first and second halves form a beam substantially off-axis relative to the surface normal of said smooth upper surface.
14. The lens of claim 13 wherein said deflection angle is 30° or more.
15. The lens of claim 13 wherein said lens is for use on a vehicle.
16. The lens of claim 13 wherein said smooth upper surface has a curvature conformal with that of the surface onto which said lens is installed.
17. A tilted-beam Illumination lens, comprising:
a smooth upper surface; and
a lower surface comprising a plurality of deflective facets having a bilaterally symmetric TIR lens profile wherein said TIR lens profile is titled relative to the surface normal of said smooth upper surface; and
a rim angle greater than 90° such that said lens forms a beam substantially off-axis relative to the surface normal of said smooth upper surface.
18. The lens of claim 17 wherein said deflection angle is 30° or more.
19. The lens of claim 17 wherein said lens is for use on a vehicle.
20. The lens of claim 17 wherein said smooth upper surface has a curvature conformal with that of the surface onto which said lens is installed.
21. A method of redirecting radiant energy, comprising the steps of:
situating a lens on a body, wherein said lens has a smooth upper surface and a lower surface having a plurality of deflective facets, wherein said facets are both refractive and totally internally reflecting; and
deploying said plurality of deflective facets asymmetrically about an axis tilted from the surface normal of said upper surface; and
receiving light from a common focal zone; and
forming a beam of light from said lower surface; and
transmitting said beam of light with a net deflection angle relative to said surface normal of said smooth upper surface.
22. The method of claim 21 wherein said body is a vehicle.
23. The method of claim 21 wherein said deflection angle is 30° or more.
24. The method of claim 21 wherein said smooth upper surface has a curvature conformal with that of the surface onto which said lens is installed.