Fiber optic illumination system having diffraction grating wavelength selector

• US 6,270,244 B1
• Filed: 11/16/1999
• Issued: 08/07/2001
• Est. Priority Date: 11/16/1999
• Status: Expired due to Fees

• Current Assignee: Light Beam Industries, LLC
• Original Assignee: DN Labs, Inc.
• Inventors: Naum, Daniel
• Primary Examiner(s): O'Shea, Sandra
• Assistant Examiner(s): Negron, Ismael
• Application Number:
  US09/441,038
• Time in Patent Office: 630 Days
• Field of Search: 362/551, 362/552, 362/555, 362/582, 362/583, 362/559, 362/560, 362/293, 362/268, 359/238, 359/245, 359/566, 385/31, 385/37, 385/39, 385/43, 405/47
• US Class Current: 362/583
• CPC Class Codes: G02B 6/0006 Coupling light into the fibre in general G02B6/4298
• CPC Class Codes: G02B 6/0026 Wavelength selective element, sheet or layer, e.g. filter or grating
• CPC Class Codes: G02B 6/0028 Light guide, e.g. taper
• CPC Class Codes: G02B 6/003 Lens or lenticular sheet or layer
• CPC Class Codes: G02B 6/0053 Prismatic sheet or layer; Brightness enhancement element, sheet or layer
• CPC Class Codes: G02B 6/0055 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0063 for extracting light out both the major surfaces of the light guide
• CPC Class Codes: G02B 6/0068 Arrangements of plural sources, e.g. multi-colour light sources
• CPC Class Codes: G02B 6/2931 Diffractive element operating in reflection
• CPC Class Codes: G02B 6/29313 characterised by means for controlling the position or direction of light incident to or leaving the diffractive element, e.g. for varying the wavelength response switching G02B6/35
• CPC Class Codes: G02B 6/4298 coupling with non-coherent light sources and/or radiation detectors, e.g. lamps, incandescent bulbs, scintillation chambers

Abstract

A fiber optic illumination system includes a light source, a waveguide, a primary optical fiber, a diffraction grating wavelength selector, and a secondary optical fiber. One or more lamps and/or solid-state devices may be employed as the light source. The waveguide includes a straight collecting segment, a tapered condensing segment, and a straight homogenizing segment, may be fabricated from fused silica as a single monolithic component, conveys light from the light source to the primary optical fiber by transmission and/or internal reflection, and may be provided with UV and/or IR blocking filter coating(s). The primary optical fiber may be colorless or fluorescent optical fiber. Light transmitted by the primary optical fiber may be divided into its constituent wavelength components by the diffraction grating, and a desired wavelength component may be received by, transmitted by, and emitted from the secondary optical fiber.

Claims

1. A fiber optic illuminator, comprising:

a light source;

a waveguide for collecting the light from the light source and coupling the light into the input end of the primary optical fiber;

a primary optical fiber, having an input end and an output end, for receiving light from the light source at the input end, transmitting the light, and emitting the light at the output end;

a diffraction grating for receiving the light emitted from the output end of the primary optical fiber and diffracting wavelength components of the light; and

a secondary optical fiber, having an input end and an output end, for receiving a selected diffracted wavelength component at the input end, transmitting the selected wavelength component, and emitting the selected wavelength component at the output end,

wherein the waveguide comprises;

a collecting segment having a substantially constant transverse profile along the length thereof;

a homogenizing segment having a substantially constant transverse profile along the length thereof, the homogenizing segment transverse profile being smaller than the collecting segment transverse profile; and

a condensing segment between the collecting segment and the homogenizing segment,

wherein;

an input end of the condensing segment is connected to an output end of the collecting segment;

the input end of the condensing segment has a transverse profile substantially the same as the collecting segment transverse profile;

an output end of the condensing segment is connected to an input end of the homogenizing segment;

the output end of the condensing segment has a transverse profile substantially the same as the homogenizing segment transverse profile; and

a transverse profile of the condensing segment tapers along the length thereof from the input end of the condensing segment to the output end of the condensing segment.

2. A fiber optic illuminator as recited in claim 1, wherein the waveguide is fused silica.

3. A fiber optic illuminator as recited in claim 1, further comprising at least one of:

an infrared-reflecting coating applied to at least one of an input end of the collecting segment and an output end of the homogenizing segment; and

an ultra-violet-reflecting coating applied to at least one of the input end of the collecting segment and the output end of the homogenizing segment.

4. A fiber optic illuminator as recited in claim 1, wherein the transverse profile of the collecting segment is substantially rectangular.

5. A fiber optic illuminator as recited in claim 1, wherein the transverse profile of the of the collecting segment is substantially circular.

6. A fiber optic illuminator as recited in claim 1, wherein the collecting segment includes a bend and a flat face for internally reflecting the light, thereby redirecting the light around the bend.

7. A fiber optic illuminator as recited in claim 1, wherein:

the collecting segment is between about 2 mm long and about 150 mm long and between about 3 mm wide and about 100 mm wide;

the condensing segment tapers at an angle between about 0.5° and

about 20°

;

the homogenizing segment is between about 5 mm long and about 100 mm long; and

the transverse profile of the homogenizing segment substantially corresponds to a transverse profile of the input end of the primary optical fiber.

8. A fiber optic illuminator as recited in claim 7, wherein:

the collecting segment is between about 10 mm long and about 100 mm long and between about 5 mm wide and about 50 mm wide;

the condensing segment tapers at an angle between about 2° and

about 12°

; and

the homogenizing segment is between about 20 mm long and about 80 mm long.

9. A fiber optic illuminator as recited in claim 7, wherein the primary optical fiber has a core diameter of between about 1 mm and about 30 mm.

10. A fiber optic illuminator as recited in claim 9, wherein the primary optical fiber has a core diameter of between about 3 mm and about 15 mm.

11. A fiber optic illuminator, comprising:

a solid-state light source;

a primary optical fiber, having an input end and an output end, for receiving light from the light source at the input end, transmitting the light, and emitting the light at the output end;

a diffraction grating for receiving the light emitted from the output end of the primary optical fiber and diffracting wavelength components of the light; and

a secondary optical fiber, having an input end and an output end, for receiving a selected diffracted wavelength component at the input end, transmitting the selected wavelength component, and emitting the selected wavelength component at the output end,

wherein the solid-state light source emits light of a primary color shorter than about 550 nm in wavelength, and the primary optical fiber is doped with at least one fluorescent dye that absorbs the light of the primary color and emits light of a secondary color, the emitted secondary color being emitted from at least one of the output end and sides of the primary optical fiber.

12. A fiber optic illuminator as recited in claim 11, wherein light of the secondary color is produced at the output end of the primary optical fiber.

13. A fiber optic illuminator as recited in claim 11, wherein:

the solid-state light source emits light of a primary color shorter than about 480 nm in wavelength;

the primary optical fiber is doped with a plurality of fluorescent dyes each emitting light of one of a plurality of secondary colors;

at least one of the plurality of fluorescent dyes absorbs the light of the primary color; and

the emitted light of at least two of the primary color and the plurality of secondary colors produces white light at the output end of the primary optical fiber.

14. A fiber optic illuminator, comprising:

a primary optical fiber, having an input end and an output end, for receiving light from a light source at the input end, transmitting the light, and emitting the light at the output end;

a diffraction grating for receiving the light emitted from the output end of the primary optical fiber and diffracting wavelength components of the light; and

a secondary optical fiber, having an input end and an output end, for receiving a selected diffracted wavelength component at the input end, transmitting the selected wavelength component, and emitting the selected wavelength component at the output end,

wherein the diffraction grating may be scanned, thereby changing the wavelength of the diffracted wavelength component transmitted by the secondary optical fiber.