LED light source for fiber optic cable

• US 20110085348A1
• Filed: 10/13/2009
• Published: 04/14/2011
• Est. Priority Date: 10/13/2009
• Status: Abandoned Application

• Current Assignee: Fiberoptics Technology, Inc.
• Original Assignee: Fiberoptics Technology, Inc.
• Inventors: Dobson, Paul J.
• Application Number:
  US12/587,757
• Publication Number:
  US 20110085348A1
• Time in Patent Office: Days
• US Class Current: 362/551
• CPC Class Codes: G02B 6/0008 the light being emitted at the end of the fibre
• CPC Class Codes: G02B 6/4298 coupling with non-coherent light sources and/or radiation detectors, e.g. lamps, incandescent bulbs, scintillation chambers
• CPC Class Codes: G02B 6/43 Arrangements comprising a plurality of opto-electronic elements and associated optical interconnections

Abstract

A high efficiency fiber optic illuminator comprises a light emitting device with wide angular light distribution, such as an LED, and an outwardly tapered fiber optic waveguide rod with a large calculated numerical aperture, preferably equal to or greater than 0.7 and a ratio of the output diameter to the input diameter of between 1.4:1 and 2.2:1. The smaller, input end of the tapered rod is supported close to the light emitting surface so as to collect the maximum amount of energy. The input end is capable of accepting light at very high angles of incidence, and reducing those angles of incidence so that when the light exits the larger, output end the light may be accepted by standard fiber optic devices with typical numerical aperture values ranging between 0.4 and 0.7.

Claims

1. A high efficiency fiber optic illuminator comprising a light emitting source and an elongated fiber optic waveguide having an input end confronting the source and an output end to be mated with a fiber optic device, wherein the waveguide tapers outwardly between the input end and the output end.

2. The illuminator of claim 1, wherein the waveguide has a circular cross section over its entire length.

3. The illuminator of claim 2, wherein the waveguide has a length L from the input end E1 to the output end E2, the taper begins from a minimum diameter D1 at the input end E1 and increases to a maximum diameter D2 at a position P along the length.

4. The illuminator of claim 3, wherein position P is at the output end E2.

5. The illuminator of claim 3, wherein position P is between the input end E1 and the output end E2, and the waveguide has a uniform diameter D2 between position P and the output end E2.

6. The illuminator of claim 1, wherein the waveguide comprises an optically conductive core having a core index of refraction N1 and an optically reflective cladding having a cladding index of refraction N2 that is lower than the core index of refraction.

7. The illuminator of claim 6, wherein the cladding is a layer of solid material integrally connected to and completely surrounding the core.

8. The illuminator of claim 6, wherein the cladding is a gaseous material surrounding and in intimate contact with the core.

9. The illuminator of claim 1, wherein the light emitting source is a light emitting diode (LED).

10. The illuminator of claim 9, wherein

the waveguide has a circular cross section over its entire length L, between the input end E1 and the output end E2;

the taper begins from a minimum diameter D1 defining an area A1 at the input end E1 and increases to a maximum diameter D2 toward the output end E2 such that D2 defines a maximum area A2;

the LED has a flat, light emitting surface having an area S; and

the area A1 of the input end of the waveguide confronts the area S of the light emitting surface.

11. The illuminator of claim 10, wherein the light emitting surface includes a glass cover and the input end E1 of the waveguide is supported perpendicularly to and in spaced relation within 0.030 inch from the glass cover.

12. The illuminator of claim 1, wherein

the waveguide comprises an optically conductive core having a core index of refraction N1 and an optically reflective cladding having a cladding index of refraction N2 that is less than the core index of refraction;

the waveguide has a circular cross section over its entire length L, from the input end E1 to the output end E2;

the taper begins from a minimum diameter D1 defining an area A1 at the input end E1 and increases to a maximum diameter D2 toward the outlet end E2 such that D2 defines a maximum area A2; and

the numerical aperture of the waveguide is at least about 0.7, calculated as the square root of the difference (N1²−

N2²).

13. The illuminator of claim 12, wherein the ratio D2/D1 lies between about 1.4 and 2.2.

14. The illuminator of claim 3, wherein a plurality of substantially identical LED light sources are arrayed in a closely spaced pattern and a respective plurality of said waveguides are arrayed with their input ends in a corresponding closely spaced pattern confronting the light sources.

15. The illuminator of claim 5, wherein

a plurality of substantially identical LED light sources are arrayed in a closely spaced pattern and a respective plurality of said waveguides are arrayed with their input ends in a corresponding closely spaced pattern confronting the light sources;

and

the uniform diameter portion of diameter D2 between position P and the output end E2 of each waveguide is in line contact with the uniform diameter portion of another waveguide.

16. The illuminator of claim 15, wherein

each waveguide comprises an optically conductive core having a core index of refraction N1 and an optically reflective cladding having a cladding index of refraction N2 that is less than the core index of refraction;

each waveguide has a circular cross section over its entire length L, from the input end E1 to the output end E2;

the taper begins from a minimum diameter D1 defining an area A1 at the input end E1 and increases to a maximum diameter D2 toward the outlet end E2 such that D2 defines a maximum area A2; and

the numerical aperture of the waveguide is at least about 0.7, calculated as the square root of the difference (N1²−

N2²).

17. The illuminator of claim 16, wherein the ratio D2/D1 lies between about 1.4 and 2.2.

18. The illuminator of claim 17, wherein

the illuminator has a base with six LED chips surrounding a central LED chip and a respective six waveguides surrounding a central waveguide;

the input ends E1 of the waveguides are fixtured in spaced relation from the respective LED'"'"'s; and

the uniform diameter end portions of all the waveguides have longitudinal line contact with at least two adjacent waveguides.

19. The illuminator of claim 12, wherein

the light source is an LED having a glass cover and the input end E1 of the waveguide is supported perpendicularly to and in spaced relation within the range of about 0.005 to 0.010 inch from the glass cover;

the numerical aperture of the waveguide is at least 0.8; and

the ratio D2/D1 lies between about 1.4 and 2.2.

20. The illuminator of claim 19, including an optic device at the output end E2 of the waveguide having a numerical aperture in the range of 0.4 to 0.7.

21. The illuminator of claim 1, wherein

the waveguide comprises an optically conductive core having a core index of refraction N1 and an optically reflective cladding having a cladding index of refraction N2 that is less than the core index of refraction;

the waveguide has a uniformly shaped cross section over its entire length L, from the input end E1 to the output end E2;

the taper begins from a minimum area A1 at the input end E1 and increases to a maximum area A2 at or adjacent to the output end E2; and

the numerical aperture of the waveguide is at least 0.8, calculated as the square root of the difference (N1²−

N2²).