Optical devices for guiding illumination
Optical devices for guiding illumination are provided each having a body of optical material with staircase or acutely angled ramp structures on its top surface for distributing light inputted from one end of the device from the front exit faces of such structures along certain angular orientations, while at least a substantial portion of the light is totally internally reflected within the body until distributed from such front exit faces. Optical devices are also provided each have a body of optical material having a bottom surface with acutely angled ramp structures and falling structures which alternate with each other, such that light is totally internally reflected within the device until reflected by such ramp structures along the bottom surface to exit the top surface of the device or transmitted through the ramp structures to an adjacent falling structure back into the device. Acutely angled ramp structures may be provided on both top and bottom surfaces of optical devices for distributing light along such top surface. Illumination apparatuses are also provided using such optical devices.
1. An optical device for guiding illumination comprising:
a body with a surface having a plurality of acutely angled ramp structures; and
each of said ramp structures having a front exit face for distributing said light, in which light when inputted at one end of said device is substantially totally internally reflected within said body until substantially distributed from the front exit face of each of said ramp structures, wherein said body has a first end representing said one end for inputting light, and a second end, and said ramp structures extend along a dimension between said first end and said second end representing the axis of the device, in which said ramp structures each have a ramp surface at an acute angle with respect to said axis, and the front exit face of each of said ramp structures represents a surface at an acute angle with respect to the normal of said axis, and wherein:
Θ R represents the angle of the ramp surface with respect to said axis;
Θ EF represents the angle of said front exit face of each of said structures with respect to the normal of said axis;
said body is of material having a refractive index (NA);
R n is a ratio of the refractive index of the material of said body to a refractive index of the medium surrounding said body; and
said angles Θ R and Θ EF are selected in accordance with at least equations:
Θ
EF
≤
arc
sin
[
1
R
n
]
-
arc
sin
[
1
R
n
NA
]
arc
sin
[
R
n
*
sin
(
Θ
EF
)
]
-
Θ
EF
≥
Θ
R
.
2. The device according to claim 1 wherein said light distributed from the front exit face of each of said ramp structures distributes said light over a certain angular range from said body.
3. The device according to claim 1 wherein said light distributed from the front exit face of each of said structures distributes said light over a wide angle from said body.
4. The device according to claim 1 wherein the height of the ramp surface, the angle of the ramp surface, and the angle of the front exit face are the same for each of said ramp structures along said top surface, and wherein the spacing between adjacent ones of said ramp structures are the same along said surface.
5. An optical device for guiding illumination comprising:
a body with a surface having a plurality of acutely angled ramp structures; and
each of said ramp structures having a front exit face for distributing said light, in which light when inputted at one end of said device is substantially totally internally reflected within said body until substantially distributed from the front exit face of each of said ramp structures, wherein said body has a first end representing said one end for inputting light, and a second end, and said ramp structures extend along a dimension between said first end and said second end representing the axis of the device, in which said ramp structures each have a ramp surface at an acute angle with respect to said axis, and the front exit face of each of said ramp structures represents a surface at an acute angle with respect to the normal of said axis, and wherein the height of the ramp surface, the angle of the ramp surfaces, and the angle of the front exit face vary for one or more of said ramp structures along said surface.
6. The device according to claim 5 wherein said body has a input portion between said first one of said ramp structures said one end for inputting light.
7. The device according to claim 5 wherein the spacing between adjacent ones of said ramp structures vary for one or more of said ramp structures along said surface.
8. The device according to claim 5 further comprising a source for light inputted into said one end of said device.
9. The device according to claim 8 wherein said source represents a lamp, a single LED, an LED array, or a fiber optic light source.
10. The device according to claim 8 wherein said source and said device are located in a housing.
11. The device according to claim 10 wherein said housing is mountable on a surface.
12. The device according to claim 8 wherein said device is located in a housing, and said source comprises a fiber optic with an input end external said housing for receiving illumination and an output end extending into said housing for delivering light to said device.
13. The device according to claim 1 wherein said surface represents a first surface, said body comprises multiple portions in which one of said portions has said ramp structures along said first surface, and another of said portions has a second surface with another plurality of acutely angled ramp structures providing illumination along said first surface of said another of said portions.
14. The device according to claim 1 wherein one of more of the height of the ramp surface, the angle of the ramp surfaces, and the angle of the front exit face vary for two or more of said ramp structures along said surface.
15. The device according to claim 1 wherein each of said ramp structures is equal in size along said surface.
16. The device according to claim 1 wherein said body has a first end representing said one end for inputting light and a second end, and at least part of said device tapers in thickness between said first and second ends.
17. The device according to claim 1 further comprising a source for light inputted into said one end of said device.
18. The device according to claim 17 further comprising a housing comprising said source and said device.
19. The device according to claim 18 wherein said housing is mountable on a surface.
20. The device according to claim 1 wherein said body has an input portion between said first one of said ramp structures said one end for inputting light.
21. The device according to claim 20 wherein said input portion is shaped to facilitate transmission of light from said one end to said body having said ramp structures.