COUPLED LIGHT SOURCES

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit under 35 U.S.C. § 119(e)(1) of U.S. Provisional Application No. 62/620,398, filed on January 22, 2018, and of U.S. Provisional Application No. 62/629,676, filed on February 12, 2018, both of which being incorporated by reference herein.

TECHNICAL FIELD

The present disclosure relates to luminaires outputting to the environment continuously shaped light, e.g., a straight, curved or serpentine line of light, by using an optical system which mixes light received from a solid-state light (SSL) source through optical fibers, where the ends of the optical fibers are arranged, at a receiving end of the optical system, in single file along a path which determines the shape of the output light.

BACKGROUND

Light sources are used in a variety of applications, such as providing general illumination and providing light for electronic displays (e.g., LCDs). Historically, incandescent light sources have been widely used for general illumination purposes. Incandescent light sources produce light by heating a filament wire to a high temperature until it glows. The hot filament is protected from oxidation in the air with a glass enclosure that is filled with inert gas or evacuated. Incandescent light sources are gradually being replaced in many applications by other types of electric lights, such as fluorescent lamps, compact fluorescent lamps (CFL), cold cathode fluorescent lamps (CCFL), high-intensity discharge lamps, and solid state light sources, such as light-emitting diodes (LEDs).

SUMMARY

The present disclosure relates to a luminaire including a SSL source, an optical system, and multiple optical fibers which optically couple the SSL source to the optical system. In this manner, light emitted by the SSL source is provided to a receiving end of the optical system at the ends of the multiple optical fibers, which can be disposed in single file along a path, e.g., a straight line or a curved path. The optical system is configured to mix the light provided in this discrete manner along the path, and output the mixed light to the environment as continuous light shaped like the path.

In general, innovative aspects of the technologies described herein can be implemented in a luminaire that includes one or more of the following aspects:

In one aspect, a luminaire includes a light source; N>2 optical fibers each having an input end and an output end, the input ends optically coupled to the light source, the optical fibers configured to guide light received at the input ends to the output ends; and an optical system having a receiving end and an optical extractor extending in a forward direction, the optical system extending sideways from the forward direction along a path and configured to direct light from the receiving end to the optical extractor. The receiving end is coupled with the output ends of the optical fibers along the path to receive light from the optical fibers. Additionally, the optical extractor is configured to output the directed light to the ambient environment.

The foregoing and other embodiments can each optionally include one or more of the following features, alone or in combination. In some implementations, the output ends of the optical fibers can be arranged in single file along the path. In some implementations, a portion of the optical fibers can be bundled along a portion of their lengths between the input ends and the output ends. In some implementations, axes of the output ends of the optical fibers can be arranged in the forward direction and direct light into the optical system along the forward direction. In some implementations, the path can be a straight line. In some implementations, the path can extend in a plane perpendicular to the forward direction. In some implementations, the optical extractor can be displaced from the receiving end. In some implementations, the receiving end of the optical system can be a receiving end of the optical extractor.

In some implementations, the optical extractor can include a redirecting surface configured to reflect some of the directed light. Here, the optical extractor is configured to output the reflected light into the ambient environment in a backward angular range having directions including obtuse angles relative to the forward direction, and to output transmitted light in a forward angular range including acute angles relative to the forward direction.

In some implementations, the optical system can include a light guide extending in a forward direction and configured to guide light from an input end to an output end. Here, the input end of the light guide is optically coupled with the receiving end of the optical system to receive light, and the optical extractor is optically coupled with the output end of the light. In some cases, the optical system can include a coupler extending along the path and having input and output apertures spaced apart in the forward direction. The receiving end of the optical system includes the input apertures where the coupler receives the provided light. The coupler is configured to redirect the provided light, such that the redirected light has a collimated angular range at the output aperture of the coupler. Additionally, the input end of the light guide is connected to the output aperture of the coupler to receive the collimated light.

In some implementations, the optical system can include a coupler extending along the path and having input and output apertures spaced apart in the forward direction. Here, the receiving end of the optical system is the input aperture of the coupler where the coupler receives the provided light. The coupler is configured to condition the provided light, such that the conditioned light provided at the output aperture has an output divergence different from an input divergence of the provided light at the input aperture. Additionally, the input end of the optical extractor is spaced apart from the output aperture of the coupler in the forward direction by a first distance. In some cases, (i) the first distance, (ii) the output divergence and (iii) a width of the input aperture orthogonal to the path and the forward direction are configured such that the optical extractor receives all conditioned light. In some cases, the coupler collimates the provided light such that the output divergence is smaller than the input divergence.

In the previous implementations, the light guide can have a pair of parallel side surfaces. Here, the pair of parallel side surfaces of the light guide are planar. In some implementations, the light source can include one or more light-emitting elements (LEEs). In some cases, the LEEs include laser diodes. In some cases, multiple input ends of the optical fibers receive light from one of the LEEs.

In the previous implementations, the output ends of the optical fibers can be glued, welded, or otherwise immersion, or otherwise optically, coupled to recesses of the receiving end of the optical system. In some cases, the recesses are arranged along the path in a straight, curved or serpentine manner. In some cases, the light source is a first light source and the optical fibers are first optical fibers. In the latter cases, the luminaire can include a second light source; and second optical fibers having respective input and output ends, the input ends optically coupled with the second light source. Here, one or more of the recesses are further optically coupled with the output ends of the second optical fibers. Further, every other recess can be optically coupled only with one of the output ends of the second optical fibers. Furthermore, the first light source and the second light source can be powered independently. Also, the first light source and the second light source are configured to provide light having different spectral power distributions.

In some implementations, the output ends of the optical fibers can be arranged along the path such that a chromaticity of light provided by different subsets of adjacent output ends of the optical fibers is substantially uniform. In some implementations, the output ends can be arranged along the path such that amounts of light provided by different subsets of adjacent output ends of the optical fibers are substantially uniform.

In some implementations, the optical system can include a phosphor and the light source provides pump light configured to pump the phosphor during operation.

In another aspect, a lighting system includes a light source; a luminaire remote from the light source; a bundle of N>2 optical fibers each having an input end and an output end, the optical fibers configured to guide light received at the input ends to the output ends; a first connector configured to optically couple the input ends of the optical fibers with the light source; and a second connector configured to optically couple the output ends of the optical fibers with the luminaire. The luminaire includes (i) an optical system having a receiving end and an optical extractor displaced from the receiving end in a forward direction. The optical system extends sideways from the forward direction along a path and configured to direct light from the receiving end to the optical extractor. The luminaire also includes a receiver configured to interconnect with the second connector and optically couple the receiving end of the optical system with the output ends of the optical fibers. The optical extractor is configured to output light to the ambient environment.

The foregoing and other embodiments can each optionally include one or more of the following features, alone or in combination. In some implementations, the first connecter and the light source can be disassembled and replaced. In some implementations, the second connector and the receiver can be disassembled and replaced.

The details of one or more implementations of the technologies described herein are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages of the disclosed technologies will become apparent from the description, the drawings, and the claims. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1A shows an example of a luminaire that includes a SSL source, multiple optical fibers, and an optical system.

Figures 1B-1D show aspects of the multiple optical fibers of the luminaire from Figure 1 A. Figure 1E is an intensity profile of light output by the luminaire from Figure 1 A.

Figure 2 shows an example of a luminaire that includes a SSL source, multiple optical fibers, and a light guide-based optical system.

Figures 3A-3B show aspects of SSL light sources used in the luminaire from Figure 2.

Figures 4A-4B show aspects of forming discrete virtual light sources arranged in single file at the receiving end of the optical system used in the luminaire from Figure 2.

Figures 5A-5B show aspects of multiplexing the discrete virtual light sources formed as shown in Figure 4 A.

Figures 6A-6D show aspects of the light guide-based optical system used in the luminaire from Figure 2.

Figure 7 shows an example of a luminaire that includes a SSL source, multiple optical fibers, and an optical system with spaced-apart optical components.

Figure 8 shows an example of a luminaire that includes a SSL source, multiple optical fibers, and an optical extractor.

Figure 9 shows aspects of forming discrete virtual light sources arranged in single file at the receiving end of the optical extractor used in the luminaire from Figure 8.

Reference numbers and designations in the various drawings indicate exemplary aspects, implementations of particular features of the present disclosure.

DETAILED DESCRIPTION

The present disclosure relates to luminaires, also referred to as light fixtures, and lighting systems for providing direct and/or indirect illumination. The disclosed luminaires and lighting systems can efficiently transport and distribute light emitted by one or more light sources towards work surfaces and/or towards background regions. The light from the light sources is received at an input end of an optical system via optical fibers and transported to an output end of the optical system. Luminaires according to the present technology output light by extracting the transported light from the output end of the optical system with an optical extractor. The light sources can be or include solid-state light sources (SSL).

In some implementations, the luminaire includes the light sources. In some implementations, the light sources are remote from the luminaire and in combination are referred to as a lighting system.

Figure 1A illustrates a block diagram of a luminaire/lighting system 100 according to the present technology that includes a SSL source 110, an optical fiber bundle 112, and an optical system 105.

Figure 1B (1C) shows that the optical fiber bundle 112 includes N > 2 optical fibers 1 l4b (1 l4c) and can be implemented as a fiber pipe, bundle or ribbon in which the constituent optical fibers are protected by a sheath 1 l6b (1 l6c) having a circular (flattened) transverse cross-section.

Input and output ends of the optical fibers can be optomechanically coupled with the light source and the optical system for example directly or via respective first and second connectors. In latter implementations, the light source and the optical system have respective receivers configured to suitably couple with the respective first and second connectors. Some implementations have connectors that can be non-destructively detached and replaced. Connectors and receivers are configured to facilitate adequate and reliable alignment of optical apertures of respective input and output ends of the optical fibers with optical apertures of the light source and the optical system. Connectors and receivers may be part of more complex interconnect systems including splitters, switches and so forth which may be configured to control amounts of light distributed via an optical fiber network. Connectors, receivers and/or interconnect systems may be particularly useful in lighting system when coupling luminaires with remote light sources.

Referring again to Figure 1A, the optical system 105 includes an optical extractor 140 which has a receiving end 149. Moreover, the optical extractor 140 is elongated and extends out- of-the-page (e.g., along the y-axis of the Cartesian reference system shown in Figure 1 A) and has a width L. Generally, the width L of the optical extractor 140 can vary as desired. Typically, the width L is in a range from about 1 cm to about 200 cm (e.g., 20 cm or more, 30 cm or more, 40 cm or more, 50 cm or more, 60 cm or more, 70 cm or more, 80 cm or more, 100 cm or more, 125 cm or more, or, 150 cm or more).

Generally, the SSL source can include one or more discrete light sources each of which can be optically coupled with one or more fibers. The SSL light source and the optical system can be coupled via one or more fiber bundles. Multiple luminaires can share one or more SSL light sources.

Figures 1A and 1D show that output ends 118 of the I ^st , ..., j* ... , N ^th optical fibers are unraveled from the optical fiber bundle 112 and arranged, at a receiving end of the optical system 105, in single file along a path extending across the width L. Note that the path, over which the fiber output ends 118 are arranged, can be a straight, curved or serpentine line in the (x,y) plane.

In the example illustrated in Figures 1A and 1D, the fiber output ends 118 are optically coupled with the optical system so that light injection occurs nominally perpendicular to the input aperture of the optical system for all fibers. Generally, such injection can occur at other than normal angles, for example at oblique angles. Furthermore, the injection angles can be different for different fibers. Oblique injection can occur within the y-plane - see coordinate system indicated in Figure 1A. Additionally, the injection direction can be rotated about the z-axis and out of a sectional plane resulting in azimuth and polar angles other than 0 and 90 degrees. Pure oblique lateral injection occurs within the x-plane only. Oblique injection can affect the distribution of light output by the luminaire.

During operation of the luminaire 100, light emitted by the SSL light source 110 is transported through the optical fiber bundle 112 and provided at the fiber output ends 118 to form N discrete virtual light sources along the noted path on the receiving end of the optical system 105. N will generally depend, inter alia , on the width L. As such, more optical fibers will be used in the optical fiber bundle 212, and correspondingly more discrete virtual light sources will be formed at the fiber output ends 118 arranged along the noted path on the receiving end of the optical system 105, for wider luminaires. In some implementations, the optical fiber bundle 112 can include between 2 and 1,000 optical fibers (e.g., to form about 10, about 50, about 100, about 200, about 500 discrete virtual light sources). Generally, the density of discrete virtual light sources (e.g., the number of discrete virtual light sources per unit length) will also depend on the nominal power of the discrete virtual light sources and illuminance desired from the luminaire 100. For example, a relatively high density of discrete virtual light sources can be formed in applications where high illuminance is desired or where low power discrete virtual light sources are formed. In some implementations, the noted path at the receiving end of the optical system 105 has a density of discrete virtual light sources along its length of 0.1 virtual light source per centimeter or more (e.g., 0.2 per centimeter or more, 0.5 per centimeter or more, 1 per centimeter or more, 2 per centimeter or more). The density of discrete virtual light sources may also be based on a desired amount of mixing of light emitted by the N discrete virtual light sources, where the mixing is performed by the optical system 105, as described below.

Moreover, each of the N discrete virtual light sources formed along the noted path on the receiving end of the optical system 105 emits light within a first angular range 115. Such light can have a Lambertian distribution, e.g., relative to the z-axis. Note that the divergence of the first angular range 115 depends, at least in part, on the numerical aperture (NA) of each of the fiber output ends 118. As used herein, providing light in an“angular range” refers to providing light that propagates in one or more prevalent directions in which each has a divergence with respect to the corresponding prevalent direction. In this context, the term “prevalent direction of propagation” refers to a direction along which a portion of an intensity distribution of the propagating light has a maximum. For example, the prevalent direction of propagation associated with the angular range can be an orientation of a lobe of the intensity distribution. (See, e.g., Figure 1E.) Also in this context, the term“divergence” refers to a solid angle outside of which the intensity distribution of the propagating light drops below a predefined fraction of a maximum of the intensity distribution. For example, the divergence associated with the angular range can be the width of the lobe of the intensity distribution. The predefined fraction can be 10%, 5%, 1%, or other values, depending on the lighting application.

The optical system 105 can also include either a light guide 130, or one or more optical couplers 120, or a combination of both. As such, for various implementations of the luminaire 100, e.g., the ones listed in Table 1, the receiving end of the optical system 105 corresponds to a receiving end of an optical system component having the smallest separation, along the luminaire lOO’s optical path, from the SSL source 110.

Table 1

For example, for the first implementation noted in Table 1, the optical system 105 includes a light guide 130 formed from a transparent material. The light guide 130 has a receiving end 13 la and an opposing end 13 lb. A length D of the light guide 130 corresponds to the distance D, measured along a forward direction, e.g., along the z-axis, between the receiving end 13 la and the opposing end 13 lb, and can be 5, 10, 20, 50 or lOOcm, for instance. Additionally, the light guide 130 has side surfaces l32a and l32b that are optically smooth and extend from the receiving end 13 la to the opposing end 13 lb. Although, they can be planar, curved or otherwise shaped, the side surfaces l32a and l32b of the light guide 130 are parallel to each other. A width of the light guide 130, along the y-axis, corresponds to the width L of the optical extractor 140. Note that the light guide 130 is either (i) integrally formed with the optical extractor 140, or (ii) its opposing end 13 lb is glued or welded to the receiving end 149 of the optical extractor 140.

Here, the fiber output ends 118 are glued, welded, or otherwise immersion or otherwise optically coupled to the receiving end 13 la of the light guide 130, and are arranged in single file along the width L of the light guide. As such, the light guide 130 receives the light emitted, in the first angular range 115, by each of the N discrete virtual light sources formed at the fiber output ends 118, and guides the received light in a forward direction, e.g., along the z-axis, from the receiving end 13 la to the opposing end 13 lb. Note that when the divergence of the light emitted in the first angular range 115 and a refractive index n of the light guide 130 satisfy the condition

2Q < the light guided through the light guide propagates through total

internal reflection (TIR) off the side surfaces l32a and l32b.

For certain numerical apertures (NAs) of the fiber output ends 118, the divergence of the first angular range 115 may not be small enough to satisfy the above-noted threshold TIR condition. In such cases, the luminaire 100 can be configured in accordance with the second implementation noted in Table 1. Here, the optical system 105 includes, in addition to the light guide 130, one or more couplers 120, each of which having a receiving end l23a and an opposing end l23b. The one or more couplers 120 are arranged, along the y-axis, over the width L of the light guide 130. Here, the one or more couplers 120 are either (i) integrally formed with the light guide 130, or (ii) their opposing ends l23b are glued or welded to the input end 13 la of the light guide 130. Additionally, the fiber output ends 118 are glued, welded, or otherwise immersion or otherwise optically coupled to the receiving end l23a of the corresponding coupler(s) 120, and are arranged in single file along the cumulative width L of the coupler(s).

In this manner, the one or more couplers 120 (i) receive the light emitted, in the first angular range 115, by the N discrete virtual light sources formed at the fiber output ends 118, and (ii) redirect it, in a second angular range 125, to the receiving end 13 la of the light guide 130. The coupler(s) 120 is/are shaped to transform the first angular range 115 into the second angular range 125 via total internal reflection, specular reflection or both. Here, the divergence of the second angular range 125 is smaller than the divergence of the first angular range 115, so the above-noted TIR condition can be satisfied. As such, all the light redirected by the coupler(s) 120 in the second angular range 125 can now be injected into the light guide 130.

Further, for both the first and second implementations noted in Table 1, because the side surfaces l32a, l32b are parallel to each other, a third angular range 135 of the guided light at the opposing end 13 lb of the light guide 130 has at least substantially the same divergence as the angular range 115 (when the light guide 130 receives the light directly from the N discrete virtual light sources formed at the fiber output ends 118) or 125 (when the light guide 130 receives the light directly from the coupler(s) 120) of the light received at the receiving end 13 la.

Note that the length D (along the z-axis), a width L (along the y-axis) and a thickness T (along the x-axis) of the light guide 130 are designed to homogenize the light emitted by the N discrete virtual light sources formed at the fiber output ends 118 as it is guided from the receiving end 13 la to the opposing end 13 lb of the light guide. In this manner, the homogenizing of the provided light - as it is guided through the light guide - causes a change of a discrete profile along the y-axis of the first angular range 115 (when the light guide 130 receives the light directly from the N discrete virtual light sources formed at the fiber output ends 118) or the second angular range 125 (when the light guide 130 receives the light from the coupler(s) 120) to a continuous profile along the y-axis of the third angular range 135 in which the discrete profile is partially or fully blurred.

Additionally, for both the first and second implementations noted in Table 1, the optical extractor 140 outputs the light received from the light guide 130 into the ambient environment, in one or more output angular ranges described in detail below.

As another example, for the third implementation noted in Table 1, the optical system 105 includes the one or more couplers 120 spaced apart from the optical extractor 140 by free space. Each of the couplers 120 has a receiving end 123 a and an opposing end l23b, the latter being separated from the optical extractor 140 by a separation D (along the z-axis). The one or more couplers are arranged, along the y-axis, over a cumulative width L. The fiber output ends 118 are glued, welded, or otherwise immersion or otherwise optically coupled to the receiving end l23a of the corresponding coupler(s) 120, and are arranged in single file along the cumulative width L of the coupler(s). In this manner, the one or more couplers 120 (i) receive the light emitted, in the first angular range 115 at the receiving end l23a, by the N discrete virtual light sources formed at the fiber output ends 118, and (ii) redirect it, in a second angular range 125, to the opposing end l23b. The one or more coupler(s) 120 is/are shaped to transform the first angular range 115 into the second angular range 125, via total internal reflection, specular reflection or both, such that the divergence of the second angular range 125 is smaller than the divergence of the first angular range 115.

Note that the separation D (along the z-axis) between the optical coupler(s) 120 and the optical extractor 140, the width L of the optical extractor 140 (along the y-axis) and a thickness T of the optical extractor 140 (along the x-axis) are designed to homogenize the light emitted by the N discrete virtual light sources formed at the fiber output ends 118 as it is first collimated by the optical coupler(s) 120 and then directed from the optical coupler(s) 120 through free space over the distance D to the optical coupler 140. In this manner, the homogenizing of the collimated light - as it propagates through free space over the distance D from the optical coupler(s) 120 to the optical extractor 140 - causes a change of a discrete profile along the y-axis of the second angular range 125 of the collimated light to a continuous profile along the y-axis of the third angular range 135 in which the discrete profile is partially or fully blurred.

Additionally, for the third implementation noted in Table 1, the optical extractor 140 outputs the light received from the one or more couplers 120 into the ambient environment, in one or more output angular ranges described in detail below.

As yet another example, for the fourth implementation noted in Table 1, the optical system 105 includes only the optical extractor 140. Here, the fiber output ends 118 are glued, welded, or otherwise immersion or otherwise optically coupled to the receiving end 149 of the optical extractor 140, and are arranged in single file along the width L of the optical extractor. In this manner, the optical extractor 140 (i) receives the light emitted, in the first angular range 115 at the receiving end 149, by the N discrete virtual light sources formed at the fiber output ends 118, and (ii) outputs it into the ambient environment, in one or more output angular ranges.

For all the implementations noted in Table 1, the light output by the extractor 140 has a first output angular range 145' that can be substantially continuous along the y-axis and has a first output propagation direction with a component opposite to the forward direction (e.g., antiparallel to the z-axis.) In some implementations, the light output by the extractor 140 has, in addition to the first output angular range 145', a second output angular range 145" that is substantially continuous along the y-axis and has a second output propagation direction with a component opposite to the forward direction (e.g., antiparallel to the z-axis.) In this case, the first output propagation direction and the second output propagation direction have respective components orthogonal to the forward direction that are opposite (antiparallel) to each other (antiparallel and parallel to the x-axis.) In some implementations, the light output by the extractor 140 has, in addition to the first output angular range 145' and the second output angular range 145", a third output angular range 145'" that can be substantially continuous along the y-axis and has a third output propagation direction along the forward direction (e.g., along the z-axis.)

As described above, separating, by the optical fiber bundle 112 with unraveled optical fiber output ends 118, the SSL source 110, with its predetermined optical, thermal, electrical and mechanical constraints, from the optical system 105 responsible for light extraction, facilitates a greater degree of design freedom of the luminaire 100 and allows for an extended optical path of desired shape, e.g., straight, curved or serpentine lines, which can permit a predetermined level of light mixing before light is output from the luminaire 100. As an intermediary technical solution, N discrete virtual light sources are formed at the fiber output ends 118 on the input end of the optical system 105, which is disposed at an arbitrary large (or small) distance from the SSL source 110. Then, as a follow-up solution, the components of the optical system, i.e., the optical extractor 140, the light guide 130, the coupler(s) 120, and various combinations thereof, are arranged and configured to translate and redirect light emitted by the N discrete virtual light sources, formed at the fiber output ends 118, away from the receiving end of the optical system before the light is output into the ambient environment. In this manner, a virtual filament can be configured to provide substantially non-isotropic light emission with respect to planes parallel to an optical axis of the luminaire 100 (for example the z-axis.) In contrast, a typical incandescent filament generally emits substantially isotropically distributed amounts of light. The virtual filament(s) may be viewed as one or more portions of space from which substantial amounts of light appear to emanate.

Figure 1E shows an x-z cross-section of far-field light intensity profile 101 of the luminaire 100 that is elongated along the y-axis (perpendicular to the sectional plane of Figure 1 A). In some implementations, the far-field light intensity profile 101 includes a first output lobe l45a representing light output by the luminaire 100 in the first output angular range 145'. In this case, a propagation direction of the first output angular range 145' is along the about -130° bisector of the first output lobe l45a. A divergence of the first output angular range 145' is represented by a width of the first output lobe l45a.

In some implementations, in addition to the first output lobe l45a, the far-field light intensity profile 101 includes one or more of a second output lobe l45b representing light output by the luminaire 100 in the second output angular range 145", or a third output lobe l45c representing light output by the luminaire 100 in the third output angular range 145'". In this case, a propagation direction of the second output angular range 145" is along the about +130° bisector of the second output lobe l45b, and a propagation direction of the third output angular range 145'" is along the about 0° bisector of the third output lobe l45c. Further in this case, a divergence of the second output angular range 145" (represented by a width of the second output lobe l45b) is about equal to the divergence of the first output angular range 145' and both of the foregoing divergences are smaller than the divergence of the third output angular range 145"' (represented by a width of the third output lobe l45c).

As described in detail below, composition and geometry of at least (i) the couplers 120, (ii) the light guide 130, and (iii) the extractor 140 of the luminaire 100 can affect the far-field light intensity profile 101, e.g., the propagation direction and divergence associated with the first output lobe l45a, and, optionally, of the one or more of the second l45b and l45c output lobes.

Implementations of the luminaire 100 in which the optical system 105 includes, at least, the light guide 130, in addition to the optical extractor 140, is described in detail below. These implementations were referred to as first and second implementations in Table 1.

Figure 2 shows an example of a luminaire 200 that includes a SSL source 210, an optical fiber bundle 212, which has multiple optical fibers, and an optical system 205. Here, the optical system 205 includes a light guide 230 and an optical extractor 240, and optionally, one or more couplers. In the example illustrated here, the luminaire 200 is installed, in a pendant configuration, e.g., such that the optical system 205 hangs from a ceiling panel 290, for instance, to provide direct and indirect illumination to a target area (e.g., a work surface) disposed, in a room, under the optical extractor 240. The indirect illumination is provided in the following manner: the optical extractor 240 outputs light in the angular ranges 145' and 145" in backward directions, towards the ceiling 290, then the ceiling diffusely scatters this light back to the target area under the optical extractor. The direct illumination is provided by the optical extractor 240 as it outputs light in the angular range 145'" in a forward direction, towards the target area.

In the example shown in Figure 2, a receiving end 205re of the optical system 205 is recessed into the ceiling 290 through an opening 292. However, note that the use of the optical fiber bundle 212 to“transport” light emitted by the SSL source 210 to the optical system 205, allows for the SSL source 210 to be disposed at an arbitrary separation from a receiving end 205re of the optical system 205. For example, the SSL source 210 can be located at a location of a building that is one or more stories above (or below) the room where the optical system 205 hangs from the ceiling panel 290. As another example, the SSL source 210 can be located nearby, for instance right on the other side of the ceiling panel 290 and adjacent to the receiving end 205re of the optical system 205.

The SSL source 210 includes one or more light emitting elements (LEEs). In general, a LEE, also referred to as a light emitter, is a device that emits radiation in one or more regions of the electromagnetic spectrum from among the visible region, the infrared region and/or the ultraviolet region, when activated. Activation of a LEE can be achieved by applying a potential difference across components of the LEE or passing a current through components of the LEE, for example. A LEE can have monochromatic, quasi-monochromatic, polychromatic or broadband spectral emission characteristics. Examples of LEEs include semiconductor, organic, polymer/polymeric light-emitting diodes, other monochromatic, quasi-monochromatic or other light-emitting elements. In some implementations, a LEE is a specific device that emits the radiation, for example a LED die. In other implementations, the LEE includes a combination of the specific device that emits the radiation (e.g., a LED die) together with a housing or package within which the specific device or devices are placed. Examples of LEEs include also lasers and more specifically semiconductor lasers, such as vertical cavity surface emitting lasers (VCSELs) and edge emitting lasers. Further examples of LEEs include superluminescent diodes and other superluminescent devices.

Figures 3A-3B show aspects of SSL sources that can be used as the SSL source 210 in the luminaire 200. In Figure 3A, an SSL source 2l0a optically is coupled to an optical fiber bundle 212. The optical fiber bundle 212 has a source end 213 and includes N > 2 optical fibers. Input ends 214 of the optical fibers are unraveled and protrude from the source end 213 of the optical fiber bundle 212. The SSL light source 2l0a includes a substrate 202a, N > 2 light emitting elements (LEEs) 204a disposed on the substrate, and focusing optics 206a optically coupled in one-to-one correspondence with the LEEs and in one-to-one correspondence with the fiber input ends 214. The LEEs 204a can be arranged as a one-dimensional or two-dimensional array in the plane of the substrate, and the focusing optics 206a can be configured as a corresponding lens array, e.g., including refractive lenses, gradient-index (GRIN) lenses, or other lenses. Each of the LEEs 204a emits light in an emission angular range, and a corresponding one of the focusing optics 206a receives the emitted light and focuses it onto a corresponding one of the fiber input ends 214. Light provided in this manner at the fiber input ends 214 will be“transported” by the optical fiber bundle 212 to the optical system 205 of the luminaire 200. In some implementations, the LEEs 204a emit light having the same spectrum, while in other implementations, the LEEs 204a emit light having two or more different spectra. In some implementations, the LEEs 204a can be turned ON/OFF, and dimmed, independently from each other. In Figure 3B, an SSL light source 2l0b is optically coupled to an optical fiber bundle 212. The optical fiber bundle 212 has a source end 213 and includes N > 2 optical fibers. Input ends of the optical fibers are disposed at a face of the source end 213 in an arrangement like the ones shown in Figures 1B or 1C. The SSL light source 2l0b includes a substrate 202b, a single LEE 204b disposed on the substrate, and a focusing optic 206b optically coupled with the LEE and with the source end 213 of the optical fiber bundle 212. The focusing optic 206b can be a refractive lens, a GRIN lens, or another lens. The LEE 204b emits light in an emission angular range, and the focusing optic 206b receives the emitted light and collimates it to fill the entire face of the source end 213 with the collimated light. Light provided in this manner at the face of the source end 213 will be inserted in all N of the optical fibers of the optical fiber bundle 212, and will be “transported” by the optical fiber bundle 212 to the optical system 205 of the luminaire 200.

Referring again to Figure 2, the optical fiber bundle 212 has, in addition to the source end 213, a delivery end 217. Output ends 218 of the optical fibers are unraveled and protrude from the delivery end 217 of the optical fiber bundle 212. Moreover, the fiber output ends 218 are arranged in single file along the y-axis at the receiving end 205re of optical system 205. In this manner, light provided by the SSL light source 210 is transported to the optical system 205, over an arbitrary distance, and delivered at the fiber output ends 218 on the receiving edge 205re of the optical system. This method of light delivery results in forming discrete virtual light sources arranged in single file at the receiving end 205re of the optical system 205.

Forming discrete virtual light sources arranged in single file at the receiving end 205re of the optical system 205 corresponding to the first implementation noted in Table 1 is illustrated in Figure 4A. In the implementation illustrated in Figure 4A, the component of the optical system nearest to the delivery end 217 of the optical fiber bundle 212 is the light guide 230, thus, in this implementation, the receiving edge of the optical system is a receiving edge 23 la of the light guide. Here, the receiving edge 23 la of the light guide 230 has a row of recesses 234 (also referred to as openings), each one of the recesses shaped to accommodate a corresponding one of the fiber output ends 218. The recesses 234 are spaced apart from each other, e.g., along the y-axis, based on a desired linear density of the discrete virtual light sources to be formed on the receiving edge 23 la. The fiber output ends 218 are glued, welded, or otherwise immersion or otherwise optically coupled to the recesses 234. As such, light delivered at the fiber output ends 218, from the SSL light source 210, is injected, during operation of the luminaire 200, into the light guide 230 in the first angular range 115 along a forward direction, e.g., along the z-axis.

Forming discrete virtual light sources arranged in single file at the receiving end 205re of the optical system 205 corresponding to the second implementation noted in Table 1 is illustrated in Figure 4B. In the implementation illustrated in Figure 4B, the component of the optical system nearest to the delivery end 217 of the optical fiber bundle 212 is the one or more couplers 220, thus, in this implementation, the receiving edge of the optical system is a receiving edge 223a of the coupler(s). Here, the receiving edge 223a of the coupler(s) has a row of input apertures 224, e.g., corresponding to individual couplers, each one of the input apertures sized to accommodate a corresponding one of the fiber output ends 218. The input apertures 224 are spaced apart from each other, e.g., along the y-axis, based either on a desired linear density of the discrete virtual light sources to be formed on the receiving edge 223a, or on the pitch of the couplers 220. The fiber output ends 218 are glued, welded, or otherwise immersion or otherwise optically coupled to the input apertures 224. As such, light delivered at the fiber output ends 218, from the SSL light source 210, is injected, during operation of the luminaire 200, into the coupler(s) 220 in the first angular range 115 along a forward direction, e.g., along the z-axis. The coupler(s) 220 will redirect the injected light and provide it at the receiving end 23 la of the light guide 230.

Referring to all Figures 3A-3B and 4A-4B, different optical fibers may provide different amounts of light depending on how much light each fiber receives at the respective input end 214, 213 from the LEE(s) 204a, 204b and/or other factors. As such different arrangements of the output ends 218 of the fibers may provide different variations of the average amount of light within the arrangement. For example, the output ends 218 can be arranged to provide a uniform average amount of light over adjacent groups of multiple fiber ends.

The method of light delivery at the receiving edge 205re of the optical system can be modified to multiplex light provided from two or more instances of the SSL light source 210, as illustrated in Figures 5A-5B. In these examples, which corresponds to the first implementation noted in Table 1, the component of the optical system nearest to the delivery end 217 of the optical fiber bundle 212 is the one or more couplers 220. The receiving edge 23 la of the light guide which has a row of recesses 234 has been described above in connection with Figure 4A. In Figures 5A- 5B, light is delivered to the receiving edge 23 la from two SSL light sources 210', 210" through respective optical fiber bundles 212', 212". Here, the SSL light sources 210', 210" are dimmable independently, and/or configured to provide light having different spectra.

In Figure 5A, the fiber output ends 218' of the first optical fiber bundle 212' connected to the first SSL light source 210' are glued, welded, or otherwise immersion or otherwise optically coupled to respective recesses 234, and so are the fiber output ends 218" of the second optical fiber bundle 212" connected to the second SSL light source 210". Since each of the recesses 234 accommodates two fiber output ends 218', 218", the recesses 234 from Figure 5A are sized and shaped appropriately. As such, light delivered from both the first SSL light source 210' and the second SSL light source 210" is injected, during operation of the luminaire 200, into the light guide 230, through each of the recesses 234, in respective instances of the first angular range 115 along a forward direction, e.g., along the z-axis.

In Figure 5B, the fiber output ends 218' of the first optical fiber bundle 212' connected to the first SSL light source 210' are glued, welded, or otherwise immersion or otherwise optically coupled to every other one of the recesses 234, while the fiber output ends 218" of the second optical fiber bundle 212" connected to the second SSL light source 210" glued, welded, or otherwise immersion or otherwise optically coupled to the remaining ones of the recesses 234. As such, during operation of the luminaire 200, light delivered from the first SSL light source 210' is injected into the light guide 230, through every other one of the recesses 234, in a first instance of the first angular range 115, and light delivered from the second SSL light source 210" is injected into the light guide 230, through the remaining ones of the recesses 234, in a second instance of the first angular range 115.

The above techniques for combining and/or multiplexing fiber ends 218', 218" from multiple bundles are used to provide light from different sources to groups of neighboring output ends of different fibers. As a result, color/CCT control can be achieved in implementations employing multiple sources with respectively different color/CCT light and selective activation/dimming during operation.

Moreover, light sources 210, 210', 210" with different visible primary colors (red, green, blue, yellow, etc.) can be used, and/or phosphor converted light from pump sources (e.g., blue or UV or otherwise LEEs 204a, 204b), so white light can be generated, e.g., in the light guide 230, by mixing light from interleaved fibers 218', 218" from different color sources 210', 210". Phosphor can be arranged directly at the source 210, 210', 210", e.g., between the pump sources 204a, 204b and the input end 214 of the fibers, at the in-coupling edge 205re of the optical system 205, and/or elsewhere along the optical path between the source(s) 210, 210', 210" and the optical extractor 240.

Referring again to Figure 2, the optical system 205 can be configured, sized and shaped in numerous ways. Further, the optical system 205 can be fabricated from a variety of materials. Some of these configurations are described below in connection with Figures 6A-6D, in which the optical system 205 is implemented in accordance with the second implementation noted in Table 1

Referring to Figure 6A, in which a Cartesian coordinate system is shown for reference, the optical system 205 includes the optical coupler 220, the light guide 230 and the optical extractor 240. The coupler 220 has a row of input apertures 224 at its receiving edge 223a as described above in connection with Figure 4B. Light delivered at the fiber output ends 218 (only one of which is shown in Figure 6A), e.g., from the SSL light source 210, is injected, during operation of the luminaire 200, into the apertures 224 on the receiving edge 223 a of the coupler 220, in the first angular range 115 along a forward direction, e.g., along the z-axis. Once again, the positive z- direction is referred to as the“forward” direction and the negative z-direction is the“backward” direction. Sections through the optical system 205 parallel to the x-z plane are referred to as the “cross-section” or“cross-sectional plane” of the luminaire module. Also, the optical system 205 extends along the y-direction, so this direction is referred to as the“longitudinal” direction of the optical system. Implementations of the optical system 205 can have a plane of symmetry parallel to the y-z plane, be curved or otherwise shaped. This is referred to as the“symmetry plane” of the optical system.

The light guide 230 has a receiving end 23 la and an opposing end 23 lb. Here, the light guide 230 is coupled to the coupler 220 at the receiving end 23 la and to the optical extractor 240 at the opposing end 23 lb. The coupler 220, the light guide 230, and the optical extractor 240 extend a length L along the y-direction, so that the optical system 205 is an elongated optical system with an elongation of L that may be about parallel to a wall of a room (e.g., a ceiling 290 of the room).

In some implementations, optical coupler 220 includes one or more solid pieces of transparent optical material (e.g., a glass material or a transparent organic plastic, such as polycarbonate or acrylic). Here, the fiber output ends 218 are optically coupled with the optical coupler 220 through respective input apertures 224 (here, indentations) of the one or more solid pieces of transparent optical material, the indentations being distributed along the y-axis. In other implementations, optical coupler 220 includes one or more hollow reflectors. Here, the fiber output ends 218 are optically coupled with the optical coupler 220 through respective input apertures 224 (here, openings) of the one or more hollow reflectors, the openings being distributed along the y- axis.

Each of the pieces of transparent optical material of the optical coupler 220 or each of the hollow reflectors of the optical coupler 220 has surfaces 221 and 222 positioned to reflect light from the N discrete virtual light sources formed at the fiber output ends 118 towards the light guide 230. In general, surfaces 221 and 222 are shaped to collect and at least partially collimate light emitted from by the N discrete virtual light sources formed at the fiber output ends 118. In the x-z cross-sectional plane, surfaces 221 and 222 can be straight or curved. Examples of curved surfaces include surfaces having a constant radius of curvature, parabolic or hyperbolic shapes. In some implementations, surfaces 221 and 222 are coated with a highly reflective material (e.g., a reflective metal, such as aluminum or silver), to provide a highly reflective optical interface. The cross-sectional profile of optical coupler 220 can be uniform along the length L of optical system 205. Alternatively, the cross-sectional profile can vary. For example, surfaces 221 and/or 222 can be curved out of the x-z plane.

The exit aperture of the optical coupler 220 adjacent the receiving edge 23 la of light guide 230 is optically coupled to the receiving edge to facilitate efficient coupling of light from the optical coupler 220 into light guide 230. For example, the surfaces of a solid coupler and a solid light guide can be attached using a material that substantially matches the refractive index of the material forming the optical coupler 220 or light guide 230 or both (e.g., refractive indices across the interface are different by 2% or less.) The optical coupler 220 can be affixed to light guide 230 using an index matching fluid, grease, or adhesive. In some implementations, optical coupler 220 is fused to light guide 230 or they are integrally formed from a single piece of material (e.g., coupler and light guide may be monolithic and may be made of a solid transparent optical material).

The light guide 230 is formed from a piece of transparent material (e.g., glass material such as BK7, fused silica or quartz glass, or a transparent organic plastic, such as polycarbonate or acrylic) that can be the same or different from the material forming optical couplers 220. The light guide 230 extends over a length L in the y-direction, has a uniform thickness T in the x-direction, and a uniform depth (also called length) D in the z-direction. The dimensions D and T are generally selected based on the desired optical properties of the light guide (e.g., which spatial modes are supported) and/or the direct/indirect intensity distribution. During operation, light coupled into the light guide 230 from optical coupler 220 (with an angular range 125) reflects off the planar surfaces of the light guide by TIR and spatially mixes within the light guide. The mixing can help achieve illuminance and/or color uniformity, along the y-axis, at the output end 23 lb of the light guide 230 at optical extractor 240. The depth, D, of light guide 230 can be selected to achieve adequate uniformity at the exit aperture (i.e., at output end 23 lb) of the light guide. In some implementations, D is in a range from about 1 cm to about 20 cm (e.g., 2 cm or more, 4 cm or more, 6 cm or more, 8 cm or more, 10 cm or more, 12 cm or more).

In general, optical couplers 220 are designed to restrict the angular range of light entering the light guide 230 (e.g., to within +/-40 degrees) so that at least a substantial amount of the light (e.g., 95% or more of the light) is optically coupled into spatial modes in the light guide 230 that undergoes TIR at the planar surfaces. Light guide 230 can have a uniform thickness T, which is the distance separating two planar opposing surfaces 232a, 232b of the light guide. Generally, T is sufficiently large so the light guide has an aperture at first (e.g., upper) surface 23 la sufficiently large to approximately match (or exceed) the exit aperture of optical coupler 220. In some implementations, T is in a range from about 0.05 cm to about 2 cm (e.g., about 0.1 cm or more, about 0.2 cm or more, about 0.5 cm or more, about 0.8 cm or more, about 1 cm or more, about 1.5 cm or more). Depending on the implementation, the narrower the light guide the better it may spatially mix light. A narrow light guide also provides a narrow exit aperture. As such light emitted from the light guide can be considered to resemble the light emitted from a one-dimensional linear light source, also referred to as an elongate virtual filament.

While optical coupler 220 and light guide 230 are formed from solid pieces of transparent optical material, hollow structures are also possible. For example, the optical coupler 220 or the light guide 230 or both may be hollow with reflective inner surfaces rather than being solid. As such material cost can be reduced and absorption in the light guide avoided. A number of specular reflective materials may be suitable for this purpose including materials such as 3M Vikuiti™ or Miro IV™ sheet from Alanod Corporation where greater than 90% of the incident light would be efficiently guided to the optical extractor. Optical extractor 240 is also composed of a solid piece of transparent optical material (e.g., a glass material or a transparent organic plastic, such as polycarbonate or acrylic) that can be the same as or different from the material forming light guide 230. In the example implementation shown in Figure 6A, the optical extractor 240 includes redirecting (e.g., flat) surfaces 242 and 244 and curved surfaces 246 and 248. The flat surfaces 242 and 244 represent first and second portions of a redirecting surface 243, while the curved surfaces 246 and 248 represent first and second output surfaces of the optical extractor 240.

Surfaces 242 and 244 are coated with a reflective material (e.g., a highly reflective metal such as aluminum or silver) over which a protective coating may be disposed. For example, the material forming such a coating may reflect about 95% or more of light incident thereon at appropriate (e.g., visible) wavelengths. Here, surfaces 242 and 244 provide a highly reflective optical interface for light having the angular range 125 entering an input end of the optical extractor 249 from light guide 230. As another example, the surfaces 242 and 244 include portions that are transparent to the light entering at the input end 249 of the optical extractor 240. Here, these portions can be uncoated regions (e.g., partially silvered regions) or discontinuities (e.g., slots, slits, apertures) of the surfaces 242 and 244. As such, some light is transmitted in the forward direction (along the z-axis) through surfaces 242 and 244 of the optical extractor 240 in an output angular range 145"'. In some cases, the light transmitted in the output angular range is refracted. In this way, the redirecting surface 243 acts as a beam splitter rather than a mirror, and transmits in the output angular range 145"' a desired portion of incident light, while reflecting the remaining light in angular ranges 138 and 138'.

In the x-z cross-sectional plane, the lines corresponding to surfaces 242 and 244 have the same length and form an apex or vertex 241, e.g. a v-shape that meets at the apex 241. In general, an included angle (e.g., the smallest included angle between the surfaces 244 and 242) of the redirecting surfaces 242, 244 can vary as desired. For example, in some implementations, the included angle can be relatively small (e.g., from 30° to 60°). In certain implementations, the included angle is in a range from 60° to 120° (e.g., about 90°). The included angle can also be relatively large (e.g., in a range from 120° to 150° or more). In the example implementation shown in Figure 6A, the output surfaces 246, 248 of the optical extractor 240 are curved with a constant radius of curvature that is the same for both. In an aspect, the output surfaces 246, 248 may have optical power (e.g., may focus or defocus light.) Accordingly, optical system 205 has a plane of symmetry intersecting apex 241 parallel to the y-z plane.

The surface of optical extractor 240 adjacent to the lower edge 23 lb of light guide 230 is optically coupled to the input end 249 of the optical extractor. For example, optical extractor 240 can be affixed to light guide 230 using an index matching fluid, grease, or adhesive. In some implementations, optical extractor 240 is fused to light guide 230 or they are integrally formed from a single piece of material.

The emission spectrum of the luminaire 200 corresponds to the emission spectrum of the LEEs 204a/204b. However, in some implementations, a wavelength-conversion material may be positioned in the luminaire module, for example remote from the LEEs, so that the wavelength spectrum of the luminaire 200 is dependent both on the emission spectrum of the LEEs and the composition of the wavelength-conversion material. In general, a wavelength-conversion material can be placed proximate the LEEs 204a/204b, but also in a variety of different locations in optical system 205. For example, a wavelength-conversion material may be disposed adjacent to the redirecting surfaces 242 and 244 of optical extractor 240, on the exit surfaces 246 and 248 of optical extractor 240, and/or at other locations. The layer of wavelength-conversion material (e.g., phosphor) may be attached to light guide 230 held in place via a suitable support structure (not illustrated), disposed within the extractor (also not illustrated) or otherwise arranged, for example.

Wavelength-conversion material that is disposed within the extractor 240 may be configured as a shell or other object and disposed within a notional area that is circumscribed between R/n and R*(l+n ² ) ^{( 1/2)} , where R is the radius of curvature of the light-exit surfaces (246 and 248 in Figure 6A) of the extractor 240 and n is the index of refraction of the portion of the extractor that is opposite of the wavelength-conversion material as viewed from the reflective surfaces (242 and 244 in Figure 6A). The support structure may be a transparent self-supporting structure. The wavelength-conversion material diffuses light as it converts the wavelengths, provides mixing of the light and can help uniformly illuminate a surface of the ambient environment.

During operation, light exiting light guide 230 through end 23 lb impinges on the reflective interfaces at portions of the redirecting surface 242 and 244 and is reflected outwardly towards output surfaces 246 and 248, respectively, away from the symmetry plane of the luminaire module. The first portion of the redirecting surface 242 provides light having an angular distribution 138 towards the output surface 246, the second portion of the redirecting surface 244 provides light having an angular distribution 138' towards the output surface 246. The light exits optical extractor through output surfaces 246 and 248. In general, the output surfaces 246 and 248 have optical power, to redirect the light exiting the optical extractor 240 in angular ranges 145" and 145', respectively. For example, optical extractor 240 may be configured to emit light upwards (i.e., towards the plane intersecting the receiving edge 223 a and parallel to the x-y plane), downwards (i.e., away from that plane) or both upwards and downwards. In general, the direction of light exiting the luminaire module through surfaces 246 and 248 depends on the divergence of the light exiting light guide 230 and the orientation of surfaces 242 and 244.

Surfaces 242 and 244 may be oriented so that little or no light from light guide 230 is output by optical extractor 240 in certain directions. In implementations where the optical system 205 is attached to a ceiling 290 of a room (e.g., the forward direction is towards the floor), such configurations can help avoid glare and an appearance of non-uniform illuminance.

In general, the light intensity distribution provided by luminaire 200 reflects the symmetry of the optical system 205’ s structure about the y-z plane. For example, referring to Figure 1E, light output in angular range 145' corresponds to the first output lobe l45a of the far-field light intensity distribution 101, light output in angular range 145" corresponds to the second output lobe l45b of the far-field light intensity distribution 101 and light output (leaked) in angular range 145'" corresponds to the third output lobe l45c of the far-field light intensity distribution 101. In general, an intensity profile corresponding to optical system 205 will depend on the configuration of the optical coupler 220, the light guide 230 and the optical extractor 240. For instance, the interplay between the shape of the optical coupler 220, the shape of the redirecting surface 243 of the optical extractor 240 and the shapes of the output surfaces 246, 248 of the optical extractor 240 can be used to control the angular width and prevalent direction (orientation) of the output first l45a and second l45b lobes in the far-field light intensity profile 101. Additionally, a ratio of an amount of light in the combination of first l45a and second l45b output lobes and light in the third output lobe l45c is controlled by reflectivity and transmissivity of the redirecting surfaces 242 and 244. For example, for a reflectivity of 90% and transmissivity of 10% of the redirecting surfaces 242, 244, 45% of light can be output in the output angular range 145' corresponding to the first output lobe l42a, 45% light can be output in the output angular range 145" corresponding to the second output lobe l42b, and 10% of light can be output in the output angular range 145"' corresponding to the third output lobe l42c.

In some implementations, the orientation of the output lobes l45a, l45b can be adjusted based on the included angle of the v-shaped groove 241 formed by the portions of the redirecting surface 242 and 244. For example, a first included angle results in a far-field light intensity distribution 101 with output lobes l45a, l45b located at relatively smaller angles compared to output lobes l45a, l45b of the far-field light intensity distribution 101 that results for a second included angle larger than the first angle. In this manner, light can be extracted from the optical system 205 in a more forward direction for the smaller of two included angles formed by the portions 242, 244 of the redirecting surface 243.

Furthermore, while surfaces 242 and 244 are depicted as planar surfaces, other shapes are also possible. For example, these surfaces can be curved or faceted. Curved redirecting surfaces 242 and 244 can be used to narrow or widen the output lobes 145 a, l45b. Depending of the divergence of the angular range 125 of the light that is received at the input end 249 of the optical extractor, concave reflective surfaces 242, 244 can narrow the lobes l45a, l45b output by the optical extractor 240 (and illustrated in Figure 1E), while convex reflective surfaces 242, 244 can widen the lobes l45a, l45b output by the optical extractor 240. As such, suitably configured redirecting surfaces 242, 244 may introduce convergence or divergence into the light. Such surfaces can have a constant radius of curvature, can be parabolic, hyperbolic, or have some other curvature.

In general, the geometry of the elements can be established using a variety of methods. For example, the geometry can be established empirically. Alternatively, or additionally, the geometry can be established using optical simulation software, such as Lighttools™, Tracepro™, FRED™ or Zemax™, for example.

In general, optical system 205 can be designed to output light into different output angular ranges 145", 145' from those shown in Figure 6A. In some implementations, optical systems can output light into lobes l45a, l45b that have a different divergence or propagation direction than those shown in Figure 1E. For example, in general, the output lobes l45a, l45b can have a width of up to about 90° (e.g., 80° or less, 70° or less, 60° or less, 50° or less, 40° or less, 30° or less, 20° or less). In general, the direction in which the output lobes l45a, l45b are oriented can also differ from the directions shown in Figure 1E. The“direction” refers to the direction at which a lobe is brightest. In Figure 1E, for example, the output lobes l45a, l45b are oriented at approx. -130° and approximately +130°. In general, output lobes l45a, l45b can be directed more towards the horizontal (e.g., at an angle in the ranges from -90° to -135°, such as at approx. -90°, approx. - 100°, approx. -110°, approx. -120°, approx. -130°, and from +90° to +135°, such as at approx. +90°, approx. +100°, approx. +110°, approx. +120°, approx. +130°.

Luminaires can include other features useful for tailoring the intensity profile. For example, in some implementations, luminaires can include an optically diffuse material that can diffuse light in a controlled manner to aid homogenizing the luminaire module’s intensity profile. For example, surfaces 242 and 244 of the optical extractor 240 can be roughened or a diffusely reflecting material, rather than a specular reflective material, can be coated on these surfaces. Accordingly, the optical interfaces at surfaces 242 and 244 can diffusely reflect light, scattering light into broader lobes than would be provided by similar structures utilizing specular reflection at these interfaces. In some implementations these surfaces can include structure that facilitates various intensity distributions. For example, surfaces 242 and 244 can each have multiple planar facets at differing orientations. Accordingly, each facet will reflect light into different directions. In some implementations, surfaces 242 and 244 can have structure thereon (e.g., structural features that scatter or diffract light).

Surfaces 246 and 248 need not be surfaces having a constant radius of curvature. For example, surfaces 246 and 248 can include portions having differing curvature and/or can have structure thereon (e.g., structural features that scatter or diffract light). In certain implementations, a light scattering material can be disposed on surfaces 246 and 248 of optical extractor 240.

In some implementations, optical extractor 240 is structured so that a negligible amount (e.g., less than 1%) of the light propagating within at least one plane (e.g., the x-z cross-sectional plane) that is reflected by surface 242 or 244 experiences TIR at light-exit surface 246 or 248. For certain spherical or cylindrical structures, a so-called Weierstrass condition can avoid TIR. A Weierstrass condition is described for a circular structure (i.e., a cross section through a cylinder or sphere) having a surface of radius R and a concentric notional circle having a radius R/n, where n is the refractive index of the optical extractor. Any light ray that passes through the notional circle within the cross-sectional plane is incident on the surface of the circular optical extractor and has an angle of incidence less than the critical angle and will exit the circular optical extractor without experiencing TIR. Light rays propagating within spherical optical extractor in the plane but not emanating from within the notional surface can impinge on the surface of radius R at the critical angle or greater angles of incidence. Accordingly, such light may be subject to TIR and won’t exit the circular optical extractor. Furthermore, rays of p-polarized light that pass through a notional space circumscribed by an area with a radius of curvature that is smaller than R/(l+n ² ) ^{( 1/2)} , which is smaller than R/n, will be subject to small Fresnel reflection at the surface of radius R when exiting the circular optical extractor. This condition may be referred to as Brewster geometry. Implementations may be configured accordingly.

Referring again to Figure 6A, in some implementations, all or part of surfaces 242 and 244 may be located within a notional Weierstrass surface defined by surfaces 246 and 248. For example, the portions of surfaces 242 and 244 that receive light exiting light guide 230 through end 23 lb can reside within this surface so that light within the x-z plane reflected from surfaces 242 and 244 exits through surfaces 246 and 248, respectively, without experiencing TIR.

In the example implementations described above in connection with Figure 6A, the light guide-based optical system 205 is configured to output light into output angular ranges 145" and 145'. In other implementations, the light guide-based optical system 205 is modified to output light into a single output angular range 145'. In Figure 6B, such light guide-based optical system configured to output light on a single side of the light guide is referred to as a single-sided optical system and is denoted 205*. The single-sided optical system 205* is elongated along the y-axis like the optical system 205 shown in Figure 6A. Also like the optical system 205, the single-sided optical system 205* includes an optical coupler 220 having a receiving end 223a optically coupled to fiber output ends 118 of the optical fiber bundle 212, where the fiber output ends 118 are arranged in a row along the y-axis. Light delivered from the SSL source 210 at the fiber output ends 118 results in N discrete virtual light sources, each of which emits light in a first angular range 115 along the z-axis into the optical coupler 220. The optical couplers 220 are shaped to redirect the light emitted by the N discrete virtual light sources formed at the fiber output ends 118 in the first angular range 115 into a second angular range 125 that has a divergence smaller than the divergence of the first angular range at least in the x-z cross-section. Also, the single-sided optical system 205* includes a light guide 230 to guide the light redirected by the optical couplers 220 in the second angular range 125 from a first end of the light guide to a second end of the light guide. Additionally, the single-sided optical system 205* includes a single-sided extractor (denoted 240') to receive the light guided by the light guide 230. The single-sided extractor 240' includes a redirecting surface 244 to redirect the light received from the light guide 230 into a third angular range 138', like described for optical system 205 with reference to Figure 6A, and an output surface 248 to output the light redirected by the redirecting surface 244 in the third angular range 138' into a fourth angular range 145'.

A light intensity profile of the single-sided optical system 205* is represented in Figure 1E as a single output lobe l45a. The single output lobe l45a corresponds to light output by the single- sided optical system 205* in the fourth angular range 145'.

Other open and closed shapes of the optical system 205 are possible. Figures 6C and 6D show a perspective view and a bottom view, respectively, of an optical system 205" for which the light guide 230" has two opposing side surfaces 232a, 232b that form a closed cylinder shell of thickness T. In the example illustrated in Figures 6C and 6D, the x-y cross-section of the cylinder shell formed by the opposing side surfaces 232a, 232b is oval. In other cases, the x-y cross-section of the cylinder shell can be circular or can have other shapes. Some implementations of the example optical system 205" may include a specular reflective coating on the side surface 232a of the light guide 230". The optical system 205" includes an optical coupler 220 having a receiving end 223 a optically coupled to fiber output ends 118 of the optical fiber bundle 212, where the fiber output ends 118 are arranged on an elliptical path of length L (in the x-y plane) determined by the curved shape of the side surfaces 232a, 232b of the light guide 230". Light delivered from the SSL source 210 at the fiber output ends 118 results in N discrete virtual light sources, each of which emits light in a first angular range 115 along the z-axis into the optical coupler 220. The optical couplers 220 are shaped to redirect the light emitted in the first angular range 115, by the N discrete virtual light sources formed at the fiber output ends 118, into a second angular range 125 that has a divergence smaller than the divergence of the first angular range at least in the x-z cross-section.

For T = 0.05D, 0.1D or 0.2D, for instance, light from the N discrete virtual light sources formed at the fiber output ends 118 - distributed along the elliptical path of length L - that is edge- coupled into the light guide 230" through the receiving edge 223a of the optical coupler 220 can efficiently mix and become uniform (quasi-continuous) along such an elliptical path by the time it propagates to optical extractor 240.

A luminaire 200 can use optical systems 205, 205* or 205" that have light guides, e.g., 230 and 230", to guide light, from each’s input end 23 la over a distance D along the forward direction to its output end 23 lb, via TIR off its side surfaces 232a and 232b. An implementation of the luminaire 100 in which the optical system 105 does not include a light guide, instead its optical extractor 140 is separated by a distance D from its coupler 120 over free space, is described in detail below. This implementation was referred to as the third implementation in Table 1.

Figure 7 shows an example of a luminaire 700 that includes a SSL source 210, an optical fiber bundle 212, which has multiple optical fibers, and an optical system 705. Here, the optical system 705 includes one or more couplers 220 and an optical extractor 743 spaced apart from each other over free space. A separation D > 0 between the optical extractor 240 and the coupler(s) 220 is established/maintained by side frames 782a, 782b. In the example illustrated here, the luminaire 700 is installed, in a pendant configuration, e.g., such that the optical system 705 hangs from a ceiling panel 790, for instance, to provide direct and indirect illumination to a target area (e.g., a work surface) disposed, in a room, under the optical extractor 743. The indirect illumination is provided in the following manner: the optical extractor 743 reflects light in the angular ranges 145' and 145" in backward directions, towards the ceiling 790, then the ceiling diffusely scatters this light back to the target area under the optical extractor. The direct illumination is provided by the optical extractor 743 as it transmits light in the angular range 145"' in a forward direction, towards the target area.

In the example shown in Figure 7, a receiving end 223a of the coupler(s) 220 is recessed into the ceiling 790 through an opening 792. However, note that the use of the optical fiber bundle 212 to“transport” light emitted by the SSL source 210 to the optical system 705, allows for the SSL source 210 to be disposed at an arbitrary separation from the receiving end 223a. For example, the SSL source 210 can be located at a location of a building that is one or more stories above (or below) the room where the optical system 705 hangs from the ceiling panel 790. As another example, the SSL source 210 can be located nearby, for instance right on the other side of the ceiling panel 790 and adjacent to the receiving end 223a.

The SSL source 210 used as part of the luminaire 700 has been described above in connection with Figures 2 and 3A-3B. The optical fiber bundle 212 is connected to (i) the SSL source 210 as described above in connection with Figures 3A-3B, and (ii) the receiving end 223a of the coupler(s) 220 as described above in connection with Figure 4B. Since the coupler(s) 220 and the optical extractor 743 of the optical system 705 are elongated along the y-axis, the fiber output ends 218 are arranged on the receiving end 223a of the coupler(s) 220 in a single file row along the y-axis. Light delivered from the SSL source 210 at the fiber output ends 118 results in N discrete virtual light sources, each of which emits light in a first angular range 115 along a forward direction, e.g., along the z-axis, into the optical coupler 220. The coupler(s) 220 will redirect the light, which has been emitted by the N discrete virtual light sources, towards the optical extractor 743, such that the redirected light is in a second angular range 125 having a smaller divergence than the first angular range 115, at least in the x-z cross-section.

Note that the optical extractor 743 of the optical system 705 has been simplified relative to the optical extractor 240 of the optical system 205. Here, the optical extractor 743 is simply a redirecting surface to extract - to the ambient environment - the light provided by the optical coupler(s) 220. Here, the optical extractor 743 is spaced apart from an exit aperture of the optical coupler(s) 220 by a distance D and includes two reflecting surfaces arranged to form a v-groove with an apex pointing toward the optical coupler(s) 220. The distance D is selected based on a divergence of the second angular range 125 and of a transverse dimension T (along the x-axis) of the optical extractor 743, such that all light provided by the optical coupler(s) 220 in the second angular range 125 impinges on the optical extractor 743. In this manner, a first portion of the optical extractor 743 redirects some of the light received from the optical coupler(s) 220 into a third angular range 145' and another portion of the optical extractor 743 redirects the remaining light received from the optical coupler(s) 220 into a fourth angular range 145". In some cases, the optical extractor 743 is semitransparent. In this manner, a fraction of the light received from the optical coupler(s) 220 in angular range 125 is transmitted (leaks) through the optical extractor 743 in a fifth angular range 145"'. A prevalent propagation direction for the fifth angular range 145'" is in the forward direction (along the z-axis.) A light intensity profile of the optical system 705 can be represented similar to the one shown in FIG. 1E as first l45a and second l45b output lobes, and optionally as an additional third output lobe l45c.

Note that for both luminaires 200, 700, their respective optical systems 205, 705 “translated” the light emitted by the N discrete virtual light sources from an output aperture of the coupler(s) 220 to the receiving end of the respective optical extractors 240, 743 over a non-zero distance D > 0. An implementation of the luminaire 100 in which the optical system 105 includes only an optical extractor 140 is described in detail below. This implementation was referred to as the fourth implementation in Table 1.

Figure 8 shows an example of a luminaire 800 that includes a SSL source 210, an optical fiber bundle 212, which has multiple optical fibers, and an optical extractor 840. Here, the optical system only an optical extractor 840. In the example illustrated in Figure 8, the luminaire 800 is installed, in a pendant configuration, e.g., such that the optical extractor 840 hangs from a ceiling panel 890. A separation D > 0 between a receiving edge 849 of the optical extractor 840 and the ceiling 890 is established/maintained by side frames 882a, 882b. In this manner, the luminaire 800 suitably provides direct and indirect illumination to a target area (e.g., a work surface) disposed, in a room, under the optical extractor 840. The indirect illumination is provided in the following manner: the optical extractor 840 outputs light in the angular ranges 145' and 145" in backward directions, towards the ceiling 890, then the ceiling diffusely scatters this light back to the target area under the optical extractor. The direct illumination is provided by the optical extractor 840 as it outputs light in the angular range 145"' in a forward direction, towards the target area.

In the example shown in Figure 8, an opening 892 in the ceiling 890 can be equipped with a fiber-separator frame 881 configured to hold optical fibers, which have been unraveled from the output end 217 of the optical fiber bundle 212, in a suitable arrangement. Since the optical extractor 840 is elongated along the y-axis, the optical fibers can be held by the fiber-separator frame 881 in a single file row along the y-axis. In this manner, output ends 218 of the unraveled optical fibers of the optical fiber bundle 212 reach the receiving edge 849 of the optical extractor 840 arranged along a single file row along the y-axis. Note that the use of the optical fiber bundle 212 to “transport” light emitted by the SSL source 210 to the optical extractor 840, allows for the SSL source 210 to be disposed at an arbitrary separation from the optical extractor of the luminaire 800. For example, the SSL source 210 can be located at a location of a building that is one or more stories above (or below) the room where the optical extractor 840 hangs from the ceiling panel 890. As another example, the SSL source 210 can be located nearby, for instance right on the other side of the ceiling panel 890 and adjacent to the fiber-separator frame 881.

The SSL source 210 used as part of the luminaire 800 has been described above in connection with Figures 2 and 3A-3B. The optical fiber bundle 212 is connected to (i) the SSL source 210, as described above in connection with Figures 3A-3B, and (ii) the optical extractor 840. In this manner, light provided by the SSL light source 210 is transported to the optical extractor 840, over an arbitrary distance, and delivered at the fiber output ends 218 on the receiving edge 849 of the optical extractor. This method of light delivery results in forming discrete virtual light sources arranged in single file at the receiving edge 849 of the optical extractor 840. Figure 9 shows aspects of forming discrete virtual light sources arranged in single file at the receiving end 849 of the optical extractor 840 used in the luminaire 800. The receiving edge 849 of the optical extractor 840 has a row of recesses 844 (also referred to as openings), each one of the recesses shaped to accommodate a corresponding one of the fiber output ends 218. The recesses 844 are spaced apart from each other, e.g., along the y-axis, based on a desired linear density of the discrete virtual light sources to be formed on the receiving edge 849. The fiber output ends 218 are glued, welded, or otherwise immersion or otherwise optically coupled to the recesses 844. As such, light delivered at the fiber output ends 218, from the SSL light source 210, is injected, during operation of the luminaire 800, into the optical extractor 840 in the first angular range 115 along a forward direction, e.g., along the z-axis.

Referring now to both Figures 8 and 9, the optical extractor 840 is shaped like the optical extractor 240 described above in connection with Figures 2 and 6A. In this manner, a portion of the light injected into the optical extractor 840 at the fiber output ends 218 is reflected by the redirecting surface 243 and transmitted through the curved output surfaces 246, 248 into first and second output angular ranges 145', 145", respectively. Additionally, a remaining portion of the light injected into the optical extractor 840 at the fiber output ends 218 is transmitted through the redirecting surface 243 into a third output angular range 145"'. A light intensity profile of the optical extractor 840 can be represented similar to the one shown in FIG. 1E in which the first output lobe l45a corresponding to the first output angular range 145', the second output lobe l45b corresponding to the second output angular range 145", and the third output lobe l45c corresponding to the third output angular range 145'".

In conclusion, to drive miniaturization of optical systems 105 independent of the size of the light sources (LEDs chips, packages dies, lasers, generally LEEs, etc.), light sources 110 can be optically coupled to optical fiber bundles 112 at a source end of the bundle. The individual optical fibers at a delivery end of the bundle can be unraveled into suitable arrangements to fit the shape of a desired input aperture of an in-coupling subsystem 120, light guide 130 or directly with an extractor optic 140, for example. Distance of light sources 110 from a receiving end of the optical system 105 can be fairly arbitrary. Furthermore, the instant technology provides a way to effectively optically distribute light provided via a wide input aperture to multiple narrow exit apertures. For example, LED packages with light-emitting faces measuring several millimeters across can be effectively optically edge-coupled via unraveled fiber bundles with optical systems having input apertures that are only a small fraction of the extension of such an LED package.

The preceding figures and accompanying description illustrate example methods, systems and devices for illumination. It will be understood that these methods, systems, and devices are for illustration purposes only and that the described or similar techniques may be performed at any appropriate time, including concurrently, individually, or in combination. In addition, many of the steps in these processes may take place simultaneously, concurrently, and/or in different orders than as shown. Moreover, the described methods/devices may use additional steps/parts, fewer steps/parts, and/or different steps/parts, as long as the methods/devices remain appropriate.

In other words, although this disclosure has been described in terms of certain aspects or implementations and generally associated methods, alterations and permutations of these aspects or implementations will be apparent to those skilled in the art. Accordingly, the above description of example implementations does not define or constrain this disclosure. Further implementations are described in the following claims.