WO2009134573A1

WO2009134573A1 - Light injection coupler and lighting system including the same

Info

Publication number: WO2009134573A1
Application number: PCT/US2009/039061
Authority: WO
Inventors: David J. Lundin; David G. Freier; Kenneth A. Epstein; Scott D. Gullicks
Original assignee: 3M Innovative Properties Company
Priority date: 2008-04-30
Filing date: 2009-04-01
Publication date: 2009-11-05

Abstract

A light injection coupler includes an opaque housing having first, second, and third openings; a conduit extending between the first, second, and third openings, each adapted to engage end portions of engineered polymer light guides while maintaining a cavity therebetween. A cover comprising a light source is affixed to the housing and disposed proximate to and occluding the third opening, the light source being in optical communication with the highly reflective surface. A lighting system that includes the light injection coupler engaging at least one engineered polymer light guide is also disclosed.

Description

LIGHT INJECTION COUPLER AND LIGHTING SYSTEM INCLUDING THE SAME

FIELD

The present disclosure relates generally to light guide-based lighting systems.

BACKGROUND Various lighting elements are known and used in the lighting art. Some lighting elements, referred to hereinafter as "engineered polymer light guides" (abbreviated hereinafter as EPLGs), have light extraction features along their length and comprise a transparent polymeric core and optionally a cladding layer disposed on the transparent polymeric core. Light is injected (that is, enters at an angle less than or equal to the critical angle for internal reflection by the EPLG) into at least one end of an EPLG and extracted by light extraction elements (for example, notches) spaced along the length of the EPLG.

However, the development of EPLGs of lengthy dimensions has been plagued with technical problems such as, for example, managing light intensity decrease of EPLGs with increasing distance. Consequently their use has been largely limited to those applications where relatively short EPLGs can be used.

SUMMARY

In one aspect, the present disclosure provides a light injection coupler comprising: an opaque housing having first, second, and third openings; a conduit extending between the first, second, and third openings, each of the first and second openings being adapted to engage end portions of first and second engineered polymer light guides while maintaining a cavity therebetween, each engineered polymer light guide comprising a respective transparent polymeric core, the end portions of first and second engineered polymer light guides being capable of guiding light in first and second respective longitudinal directions, the conduit having a highly reflective surface adjacent to the cavity and opposite the third opening, and the end portions of first and second engineered polymer light guides each having a respective optically smooth face aligned substantially perpendicularly to its respective longitudinal direction; a cover comprising a light source, the cover being affixed to the housing and disposed proximate to and occluding the third opening, the light source being in optical communication with the highly reflective surface.

Light injection couplers according to the present disclosure are useful in fabrication of lighting systems; for example, in fabrication of a lighting system comprising at least one engineered polymer light guide engaging the first and second openings of a light injection coupler according to the present disclosure. Accordingly, in another aspect the present disclosure provides a light injection coupler comprising: an opaque housing having first, second, and third openings; a conduit extending between the first, second, and third openings; and a cover comprising a light source, the cover being affixed to the housing and disposed proximate to and occluding the third opening, the light source being in optical communication with the highly reflective surface; and at least one engineered polymer light guide comprising first and second end portions engaging the first and second openings of the light injection coupler while maintaining a cavity therebetween, each of the at least one engineered polymer light guide comprising a respective transparent polymeric core, the first and second end portions being capable of guiding light in first and second respective longitudinal directions, the conduit having a highly reflective surface adjacent to the cavity and opposite the third opening, and the first and second end portions each having a respective optically smooth face aligned substantially perpendicularly to its respective longitudinal direction.

In some embodiments, the highly reflective surface is specularly reflective. In some other embodiments, the highly reflective surface is diffusively reflective.

In some embodiments, the highly reflective surface comprises a multilayer optical film (for example, a polymeric multilayer optical film). In some embodiments, the light source comprises at least one light emitting diode. In some embodiments, the opaque housing comprises first and second portions flexibly connected by a hinge, the first and second portions being further fastened one to another by at least one mechanical fastener. In some embodiments, at least one of the first and second openings comprises a respective collar. In some embodiments, a portion of the cover is highly reflective. In some embodiments, the surface of the cavity, exclusive of the first and second end portions of the at least one engineered polymer light guide and the cover, being highly reflective. Advantageously, lighting systems including light injection couplers according to the present disclosure can be conveniently and reliably fabricated in virtually any length while maintaining acceptable aesthetically levels of illumination and appearance, especially when viewed from distances typical of their intended application. Accordingly, they are particularly useful for those applications where lengthy lighting systems are required. Examples of such applications include vehicle trim lighting, architectural lighting, and commercial signage.

Advantageously, lighting systems according to the present disclosure may be conveniently and reliably fabricated in virtually any length while maintaining acceptable aesthetically levels of illumination and appearance. As used herein:

"opaque" means impenetrable by light, and neither transparent nor translucent;

"opposite the opening" in reference to the highly reflective surface means that at least a portion of the highly reflective surface is opposite the opening, although the highly reflective surface may extend beyond that region; "disposed proximate to and occluding" means covering or disposed within and blocking transmission of light;

"highly reflective surface" means a surface that is at least 70 percent reflective to light; and

"injected into a engineered polymer light guide" means that light enters the engineered polymer light guide at an angle such that it is internally reflected and guided by the engineered polymer light guide;

"light" means visible light;

"longitudinal direction" as applied to a engineered polymer light guide refers to a direction of propagation, which may or may not be linear or planar (for example, in the case of a curved engineered polymer light guide); "optical communication" as applied to two objects means that light can be transmitted from one to the other either directly or indirectly using optical methods (for example, reflection, diffraction, refraction);

"optically smooth" means essentially free of surface features that contribute to light loss through scattering mechanisms;

"substantially perpendicularly" means at an angle of from about 80 degrees to 90 degrees.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective cutaway of an exemplary light system according to the present disclosure;

Fig. 2 is a perspective cutaway view of an exemplary light system according to the present disclosure;

Fig. 3 is an exploded perspective view of an exemplary light injection coupler according to the present disclosure; and

Fig. 4 is a perspective view of an exemplary opaque housing suitable for use in the exemplary light injection coupler shown in Fig. 3.

DETAILED DESCRIPTION Lighting systems according to the present disclosure include, for example, those shown in Figs. 1 and 2.

Referring now to Fig. 1, exemplary lighting system 100 comprises EPLGs 105a, 105b, 105c that are capable of guiding light in respective longitudinal directions 190a, 190b, 190c. EPLGs 105a, 105b, 105c respectively comprise flexible transparent polymeric cores 175a, 175b, 175c having respective optional claddings 180a, 180b, 180c thereon. Lighting system 100 comprises two cavities 120a, 120b situated adjacent respective opaque housings 150a, 150b. Each of cavities 120a, 120b is, respectively, adjacent two optically smooth faces 125a₂, 125bi and 125b₂, 125ci, and highly reflective surfaces HOa, HOb opposite openings 135a, 135b. Optically smooth faces 125a₂, 125bi and 125b₂, 125ci are aligned substantially perpendicularly to respective longitudinal directions 190a, 190b, 190c. EPLG 105 has light extraction elements 185a, 185b, 185c distributed along its length. Covers 130a, 130b, respectively, occlude openings 135a, 135b. Covers 130a, 130b comprise respective light sources 155a, 155b (shown as light emitting diodes (LEDs)). Light sources 155a, 155b are in optical communication with respective highly reflective surfaces 110a, 110b.

Yet another embodiment of an exemplary lighting system is shown in Fig. 2. Referring now to Fig. 2, exemplary lighting system 200 comprises EPLG 205 that is capable of guiding light in longitudinal direction 290. EPLG 205 comprises transparent polymeric core 275 having optional cladding 280 (not shown) thereon. Lighting system 200 comprises cavity 220, situated adjacent transparent or translucent housing 250. Cavity 220 is adjacent two optically smooth faces 225a_ls 225a₂ and highly reflective surface 210 opposite opening 235. Optically smooth faces 225a_ls 225a₂ are aligned substantially perpendicularly to longitudinal direction 290. EPLG 205 has light extraction elements 285 distributed along its length. Cover 230 is proximate to and occludes opening 235. Cover 230 comprises light source 255 (shown as multiple light emitting diodes of different colors), electrically supplied by wires 265, and in optical communication with highly reflective surface 210.

EPLGs generally comprise a transparent polymeric core and an optional cladding. Typically, the transparent polymeric core is bounded by optically smooth surfaces interrupted by one or more light extraction structures that direct light out of the EPLG. They may have any shape that is effective for internal reflection and propagation of light. Examples of suitable shapes and configurations include, for example, rods having round, square, elliptical, D-shaped, or many-sided profiles, and flat sheets or panels. For example, the EPLG may comprise a cylindrical guide (for example, an EPLG designed to emit guided light at one or more points along its length), or a planar EPLG (for example, a sheet or ribbon). Further details concerning EPLGs and methods for their manufacture may be found, for example, in U.S. Pat. Nos. 6,039,553 (Lundin et al); 6,367,941 (Lundin et al.); 6,259,855 (Lundin); 6,367,941 (Lea et al.); and RE40,227 (Cobb, Jr.). EPLGs are also available from commercial sources; for example, as 3M Precision Lighting Elements (PLEs) from 3M Company, St. Paul, MN.

Many suitable transparent polymeric cores are known in the EPLG/optical fiber art. The transparent polymeric core may be made of a material or combination of materials that is sufficiently transparent and internally reflective to effectively propagate light along a longitudinal direction (typically for a distance of at least 10 centimeters, and more typically at least one meter). Examples of suitable polymers include thermoplastic and/or thermoset polymers. The transparent polymeric core may be flexible or rigid, or anything in between, although for many applications flexibility is desirable. Exemplary transparent polymeric cores include: acrylic cores, for example, as described in are described in U.S. Pat. No. 5,898,810 (Devens et al.); and urethane cores, for example, as described in U.S. Pat. No. 6,379,592 (Lundin et al.). The transparent polymeric core typically has a refractive index of at least about 1.45, more typically at least about 1.50 or even at least about 1.55. Methods for forming suitable transparent polymeric cores are known and include, for example, extrusion, molding, and drawing. Alternatively, the transparent polymeric core may be obtained from a commercial source.

Likewise, a wide variety of suitable transparent polymeric cores are known in the EPLG/optical fiber art. Examples of materials useful for the optional cladding include heat shrinkable materials, elastomers (for example, thermoplastic polyolefms, polyamides, polyurethanes, and combinations thereof), and fluoropolymers (for example, polymerization products of tetrafluoroethylene, chlorotrifluoroethylene, hexafluoropropene, vinylidene fluoride, perfluoroalkylvinyl ethers, trifluoroethylene, and combinations thereof). An exemplary useful fluoropolymer includes the polymerization product of tetrafluoroethylene, hexafluoropropene, and vinylidene fluoride.

The optically smooth faces may be any suitable surface, including, for example, a Fresnel window or a polished surface. The optically smooth faces may optionally have a coating (for example, an antireflective coating) thereon.

The optional cladding may be made of a single polymeric layer, or may include a plurality of concentric layers. One exemplary multi-layer cladding includes (a) a first layer comprising a fluoropolymer (for example, the polymerization product of tetrafluoroethylene, hexafluoropropene, and vinylidene fluoride), (b) a second layer surrounding the first layer comprising a thermoplastic polymer (for example, a polyurethane), and (c) a third layer surrounding the second layer comprising a thermoplastic polymer (for example, a polyolefm). In general, the optional cladding, if present, has a refractive index lower than that of the transparent polymeric core on which it is disposed. Typically, the index of refraction of the optional cladding is at least about 0.05 or even at least about 0.10 less than the index of refraction of the transparent polymeric core. Both clad and unclad transparent polymeric cores are suitable for use in the present disclosure. Further details concerning the optional cladding may be found in U.S. Pat. No. 5,898,810 (Devens et al).

The size and shape of the cavity are not critical, although they should generally be selected as to maximize injection of reflected and/or direct light illumination through the optically smooth faces and injected into the EPLG(s) at an angle less than the critical angle of the EPLG.

The highly reflective surface is at least 70 percent reflective, typically at least 80 percent reflective, more typically at least 90 percent reflective, and even more typically at least 95 percent reflective. Various materials may be used to provide the highly reflective surface including, for example, vapor-coated metal (for example, silver, gold, aluminum), electroplated metal, metal salt (for example, barium sulfate) or metal oxide (for example, aluminum oxide, titanium dioxide) films, multilayer optical films (for example, as available under the trade designations "Vikuiti Enhanced Specular Reflector Film" or "Vikuiti Durable Enhanced Specular Reflector Film - Metal" from 3M Company, St. Paul, MN), and combinations thereof.

A multilayer optical film (for example, a polymeric multiplayer optical film) typically includes individual microlayers having different refractive index characteristics so that some light is reflected at interfaces between adjacent microlayers. The microlayers are sufficiently thin so that light reflected at a plurality of the interfaces undergoes constructive or destructive interference in order to give the multilayer optical film the desired reflective or transmissive properties. For multilayer optical films designed to reflect light at ultraviolet, visible, or near-infrared wavelengths, each microlayer generally has an optical thickness (a physical thickness multiplied by refractive index) of less than about 1 micrometer. However, thicker layers can also be included, such as skin layers at the outer surfaces of the multilayer optical film, or protective boundary layers disposed between the multilayer optical films that separate the coherent groupings of microlayers. Such a multilayer optical film body can also include one or more thick adhesive layers to bond two or more sheets of multilayer optical film in a laminate.

In a simple embodiment, the microlayers can have thicknesses and refractive index values corresponding to a 1/4-wave stack, that is, arranged in optical repeat units or unit cells each having two adjacent microlayers of equal optical thickness (f-ratio = 50%), such optical repeat unit being effective to reflect by constructive interference light whose wavelength λ is twice the overall optical thickness of the optical repeat unit. Thickness gradients along a thickness axis of the film (for example, the z-axis) can be used to provide a widened reflection band. Thickness gradients tailored to sharpen such band edges (at the wavelength transition between high reflection and high transmission) can also be used, as discussed in U.S. Patent 6,157,490 (Wheatley et al). For polymeric multilayer optical films, reflection bands can be designed to have sharpened band edges as well as 'flat top' reflection bands, in which the reflection properties are essentially constant across the wavelength range of application. Other layer arrangements, such as multilayer optical films having 2-microlayer optical repeat units whose f-ratio is different from 50%, or films whose optical repeat units include more than two microlayers, are also contemplated. These alternative optical repeat unit designed can be configured to reduce or to excite certain higher-order reflections; for example, as described in U.S. Pat. Nos. 5,360,659 (Arends et al.) and 5,103,337 (Schrenk et al.).

Exemplary materials that can be used in the fabrication of polymeric multilayer optical films can be found in PCT Publication WO 99/36248 (Neavin et al.). Exemplary two-polymer combinations that provide both adequate refractive index differences and adequate inter-layer adhesion include: (1) for polarizing multilayer optical film made using a process with predominantly uniaxial stretching, PEN/coPEN, PET/coPET, PEN/sPS, PET/sPS, PEN/Eastar, and PET/Eastar, where "PEN" refers to polyethylene naphthalate, "coPEN" refers to a copolymer or blend based upon naphthalenedicarboxylic acid, "PET" refers to polyethylene terephthalate, "coPET" refers to a copolymer or blend based upon terephthalic acid, "sPS" refers to syndiotactic polystyrene and its derivatives, and Eastar is a polyester or copolyester (believed to comprise cyclohexanedimethylene diol units and terephthalate units) commercially available from Eastman Chemical Co., Kingsport, TN; (2) for polarizing multilayer optical film made by manipulating the process conditions of a biaxial stretching process, PEN/coPEN, PEN/PET, PEN/PBT, PEN/PETG and PEN/PETcoPBT, where "PBT" refers to polybutylene terephthalate, "PETG" refers to a copolymer of PET employing a second glycol (usually cyclohexanedimethanol), and "PETcoPBT" refers to a copolyester of terephthalic acid or an ester thereof with a mixture of ethylene glycol and 1 ,4-butanediol; (3) for mirror films (including colored mirror films), PEN/PMMA, coPEN/PMMA, PET/PMMA, PEN/Ecdel, PET/Ecdel, PEN/sPS, PET/sPS, PEN/coPET, PEN/PETG, and PEN/THV, where "PMMA" refers to polymethyl methacrylate, Ecdel is a thermoplastic polyester or copolyester (believed to comprise cyclohexanedicarboxylate units, polytetramethylene ether glycol units, and cyclohexanedimethanol units) commercially available from Eastman Chemical Co., and THV is a fluoropolymer commercially available from 3M Company, St. Paul, MN. Further details of suitable multilayer optical films and related designs and constructions can be found, for example, in U.S. Pat. Nos. 5,882,774 (Jonza et al.), 6,297,906 Bl (Allen et al.); 6,531,230 (Weber et al.); 6,888,675 B2 (Ouderkirk et al.); and in U.S. Pat. Appln. Publ. Nos. 2002/0031676 Al (Jonza et al.) and US 2008/0037127 Al (Weber). The highly reflective surface may have specular or diffuse reflective properties, or it may have reflective properties somewhere in between. While the highly reflective surface is disposed opposite the opening, the highly reflective surface or another reflective surface may be present on the remaining surface of surfaces of the cavity other than the optically smooth faces and the light source. For example the cover, may be partially reflective. Typically, it is desirable to maximize the area and amount of reflectivity of such surfaces in order to increase the amount of reflected light that is injected into the EPLG(s). In one embodiment, the highly reflective surface is present on substantially all of surfaces of the cavity other than the optically smooth faces and the cover.

Any or all of the covers may be, for example, transparent, translucent, reflective (for example, highly reflective), opaque, or a combination thereof. Typically, the covers, and hence the openings of the corresponding cavities are oriented such that they are away from the view of an observer during the intended use. For example, any or all of the cover(s) may be situated on the same side of the lighting system, although for many applications this may be undesirable unnecessary or even aesthetically unattractive. The cover may be made of any suitable material that such as for example, metal, plastic, fϊberboard, elastomer, or circuit board.

The light extraction structures extracting light from the light guide at desired points along its length, typically with a desired intensity level. Many types of light extraction structures are known including, for example, notches and protrusions. Examples of light extraction structures and details for their fabrication may be found, for example, in U.S. Pat. Nos. 5,432,876 (Appeldorn et al.) and 6,863,428 B2 (Lundin et al.); 6,033,604 (Lundin et al.); 6,039,553 (Lundin et al.); 6,077,462 (Lundin et al.); 6,259,855 (Lundin); 6,367,941 (Lea et al); 6,379,592 (Lundin et al.); 6,623,667 (Lundin); 6,863,428 (Lundin); and 7,052,168 (Epstein et al.).

Optionally, a diffuse reflective layer may also be disposed on the transparent polymeric core and/or optional cladding of EPLGs used in practice of the present disclosure. These may be particularly useful if desiring to achieve a neon or fluorescent lighting appearance. Exemplary diffuse reflective layers are described, for example, in U.S. Pat. No. 6,863,428 B2 (Lundin et al.).

Any light suitable light source may be used; however if compact size is desired, light emitting diodes (that is, LEDs) and/or fiber optics are particularly useful. The light source may comprise multiple distinct light sources, which may be the same or different; for example, corresponding to individual colors (for example, red-blue-green). In the case of fiber optics a plurality of optical fibers may be coupled to a remotely located lamp of sufficient power, in such a way, noise and equipment associated with the lamp may be hidden from view of an observer viewing the lighting system. Lighting systems according to the present disclosure may be used, for example, for: architectural applications (for example, recessed lighting, or in lieu of fluorescent or neon lighting); signage applications (for example, as neon-type signs); and for vehicular lighting (for example, trailer trim lighting, aisle lighting, marine lighting, automobile lighting, and aircraft lighting). For example, the lighting system may be used in automotive applications such as spoilers, along the edges of rear windows, or to follow the curve of a trunk lid, as side markers, emergency flashers, and center high mounted stop lamps.

Lighting systems according to the present disclosure can be made using EPLGs and a light injection coupler(s) according to the present disclosure. Referring now to Fig. 3, exemplary light injection coupler 300 comprises opaque housing 380 having first, second, and third openings (321, 322, 323), and conduit 330 that extends therebetween. Each of the first and second openings 321, 322 has an optional respective collar 351, 352 (not shown), and is adapted to engage at least two end portions 332, 334 of EPLGs 305a, 305b while maintaining a cavity 320 therebetween. End portions 332, 334 are capable of guiding light corresponding longitudinal directions 390a, 390b. Conduit 360 has highly reflective surface 310, provided by optional multilayer optical film 312, adjacent cavity 320 and opposite third opening 323. As shown, optional multilayer optical film 312 is sized and shaped as to conform to dimensions of conduit 360 and openings 321, 322, 323 such that it fits flush against conduit 360. Typically, optional multilayer optical film 312 does not extend beyond any optional collars 351, 352 that are present.

End portions 332, 334 have respective optically smooth faces 325a, 325b aligned substantially perpendicularly to its respective longitudinal direction. Cover 330 comprises a light source 355 (shown here as a light emitting diode (LED)). Cover 330 is affixed to opaque housing 380 by screws 385 and is proximate to and occludes third opening 323 of opaque housing 380. Light source 355, electrically connected to wires 365, is in optical communication with the highly reflective surface 310 such that a major portion of any light emitted from light source 355 is reflected by the highly reflective surface, including any subsequent re-reflection from other surfaces adjacent to the cavity, and injected into first and second end portions 332, 334.

The opaque housing may be made of any suitably opaque material such as, for example: metal; wood; colored thermoset resin (for example, epoxies, melamine- formaldehyde resins, or phenolics); colored thermoplastic (for example, polyesters, polyamides, polyolefms, styrenic polymers (for example, polystyrene, ABS plastic)), and combinations thereof. In one exemplary embodiment, shown in Fig. 4, opaque housing 480 comprises first and second portions 410, 412 flexibly connected by hinge 420. When assembled, first and second portions 410, 412 are fastened one to another by a mechanical fastener shown as snap clips 430. Other suitable mechanical fasteners include rivets, screws, clamps, clips, and combinations thereof.

The disclosures of all patents and publications cited hereinabove are incorporated herein by reference in their entirety.

Various modifications and alterations of this invention may be made by those skilled in the art without departing from the scope and spirit of this invention, and it should be understood that this invention is not to be unduly limited to the illustrative embodiments set forth herein.

Claims

What is claimed is:

1. A light injection coupler comprising: an opaque housing having first, second, and third openings; a conduit extending between the first, second, and third openings, each of the first and second openings being adapted to engage end portions of first and second engineered polymer light guides while maintaining a cavity therebetween, each engineered polymer light guide comprising a respective transparent polymeric core, the end portions of first and second engineered polymer light guides being capable of guiding light in first and second respective longitudinal directions, the conduit having a highly reflective surface adjacent to the cavity and opposite the third opening, and the end portions of first and second engineered polymer light guides each having a respective optically smooth face aligned substantially perpendicularly to its respective longitudinal direction; and a cover comprising a light source, the cover being affixed to the housing and disposed proximate to and occluding the third opening, the light source being in optical communication with the highly reflective surface.

2. The light injection coupler of claim 1, the highly reflective surface being specularly reflective.

3. The light injection coupler of claim 1, the highly reflective surface being diffusively reflective.

4. The light injection coupler of any one of claim 1 to claim 3, the highly reflective surface comprising a multilayer optical film.

5. The light injection coupler of any one of claim 1 to claim 4, the light source comprising at least one light emitting diode.

6. The light injection coupler of any one of claim 1 to claim 5, the opaque housing comprising first and second portions flexibly connected by a hinge, and the first and second portions being further fastened one to another by at least one mechanical fastener.

7. The light injection coupler of any one of claim 1 to claim 6, at least one of the first and second openings comprising a respective collar.

8. The light injection coupler of any one of claim 1 to claim 7, a portion of the cover being highly reflective.

9. The light injection coupler of any one of claim 1 to claim 8, the surface of the cavity, exclusive of the first and second end portions of the at least one engineered polymer light guide and the cover, being highly reflective.

10. A lighting system comprising: a light injection coupler comprising: an opaque housing having first, second, and third openings; a conduit extending between the first, second, and third openings; and a cover comprising a light source, the cover being affixed to the housing and disposed proximate to and occluding the third opening, the light source being in optical communication with the highly reflective surface; and at least one engineered polymer light guide comprising first and second end portions engaging the first and second openings of the light injection coupler while maintaining a cavity therebetween, each of the at least one engineered polymer light guide comprising a respective transparent polymeric core, the first and second end portions being capable of guiding light in first and second respective longitudinal directions, the conduit having a highly reflective surface adjacent to the cavity and opposite the third opening, and the first and second end portions each having a respective optically smooth face aligned substantially perpendicularly to its respective longitudinal direction.

11. The light injection coupler of claim 10, the highly reflective surface being specularly reflective.

12. The light injection coupler of claim 10, the highly reflective surface being diffusively reflective.

13. The light injection coupler of any one of claim 10 to claim 12, the highly reflective surface comprising a multilayer optical film.

14. The light injection coupler of any one of claim 10 to claim 13, the light source comprising at least one light emitting diode.

15. The light injection coupler of any one of claim 10 to claim 14, the opaque housing comprising first and second portions flexibly connected by a hinge, and the first and second portions being further fastened one to another by at least one mechanical fastener.

16. The light injection coupler of any one of claim 10 to claim 15, at least one of the first and second openings comprising a respective collar.

17. The light injection coupler of any one of claim 10 to claim 16, a portion of the cover being highly reflective.

18. The light injection coupler of any one of claim 10 to claim 17, the surface of the cavity, exclusive of the first and second end portions of the at least one engineered polymer light guide and the cover, being highly reflective.