Ring-shaped phosphors in combination with axicon lenses to produce laser-pumped high-intensity white light sources

Abstract

The invention provides a light generating system (1000) comprising a first light generating device (110), a light emitter (1200), a heat conducting element (500) and an axicon-shaped optical element (400); wherein: (A) the first light generating device (110) is configured to generate first device light (111); the first light generating device (110) comprises one or more of a super light emitting diode and a solid state laser; (B) the light emitter (1200) comprises a luminescent material (200) configured to convert at least a portion of the first device light (111) into luminescent material light (201); the luminous body (1200) has an annular shape; (C) the thermally conductive element (500) (a) is configured in thermal contact with at least a portion of the light emitter (1200), and (b) is reflective for one or more of the first device light (111) and the luminescent material light (201); (D) an axicon-shaped optical element (400) comprising a first portion (410) and a second portion (420) and having an optical element length (L); the first portion (410) has a tapered shape, a first length (L1), and includes a first end window (411); the second portion (420) having a cylindrical shape, a second length (L2), and comprising a second end window (422); wherein 0.7 < = L2 / Llt; 1; and (E) the axicon-shaped optical element (400) is configured to (a) receive at least a portion of the first device light (111) via the first portion (410) and provide an annular light beam of the first device light (111) to the light emitter (1200) via the second portion (420), and (b) collect at least a portion of the luminescent material light (201) via the second portion (420) and provide a light beam of the luminescent material light (201) via the first portion (410).

Description

Technical Field

[0001] The invention relates to a light generating system and a light generating device comprising such a light generating system. Background Art

[0002] Solid-state lighting is known in the art. For example, US 7,165,871 B2 describes a lamp for generating light, the lamp comprising a semiconductor light emitting element for emitting light, a fluorescent material disposed away from the semiconductor light emitting element, a first optical member operable to focus the light generated by the semiconductor light emitting element on the fluorescent material, and a second optical member having an optical center at a location where the fluorescent material is disposed, the second optical member operable to emit light from the fluorescent material based on the light focused by the optical member to the outside of the lamp. The lamp is used as a headlamp in a vehicle, and the second optical member emits light from the fluorescent material to the outside of the lamp, so that the second optical member forms at least one of a portion of a cut line defining a boundary between a bright area and a dark area of ​​the headlamp. The document also describes a combination of a laser, a phosphor, and a reflector integrated into a light emitting module for automotive headlight applications. Summary of the invention

[0003] Laser-based light sources have attracted widespread attention due to their potential to produce relatively high flux from a relatively small emitting area. The high brightness of these sources can facilitate miniaturization and more precise control of light distribution using optical devices. It may also be desirable to have a high brightness light source for general lighting applications that can be tuned in a wide range of color spaces / CCTs with good color rendering. In general, in order to achieve color tunability, a combination of several sources with different starting color points may be required (e.g., various sources using different phosphors, different primary colors from direct emitters (e.g., RGB), or a combination of these). In order to create a high brightness color tunable light source, the multiple sources may need to be optically combined with good color mixing without additionally increasing the light collection rate. However, for systems utilizing direct RGB lasers, direct RGB lasers hinder unrealistic master laser wavelength requirements, for example due to the inherent narrow spectral width of the laser line and / or, for example, practical restrictions on certain limited spectral ranges, and the optical combination of multiple sources generally results in a relatively low CRI. In addition, for systems utilizing more than one phosphor converter, the light collection rate tends to increase significantly (such as at least x2 times), which may be undesirable for high brightness applications. Furthermore, prior art systems may require multi-channel drivers and / or additional color mixing. Furthermore, it may be desirable to use commonly available light sources without the need for specialized equipment.

[0004] It would appear desirable to have an illumination device that could be relatively compact and / or provide relatively high intensity. Furthermore, it would appear desirable that the thermal management of such an illumination device is sufficient so that such high light intensity may be possible by using a high intensity pump light source, such as for example a laser.

[0005] Therefore, one aspect of the present invention is to provide an alternative light generating system (and / or a lighting device (including such a light generating system)), which preferably also at least partially eliminates one or more of the above-mentioned disadvantages. The purpose of the present invention may be to overcome or improve at least one of the disadvantages of the prior art, or to provide a useful alternative.

[0006] According to a first aspect, the present invention provides a light generation system (“system”) comprising a first light generation device, a light emitter, a heat conducting element, and an axicon-shaped optical element. In particular, the first light generation device is configured to generate first device light. In a specific embodiment, the first light generation device may include one or more of a superluminescent diode and a solid-state laser. Further, in particular, the light emitter includes a luminescent material that may be configured to convert at least a portion of the first device light into luminescent material light. In a specific embodiment, the light emitter may have an annular shape. In an embodiment, the heat conducting element may be configured to be in thermal contact with at least a portion of the light emitter. In a specific embodiment, the heat conductor may be reflective for one or more of the first device light and the luminescent material light. In a specific embodiment, the axicon-shaped optical element may include a first portion and a second portion and may have an optical element length (L). In a further specific embodiment, the first portion may have a conical shape, may have a first length (L1), and may include a first end window. Also, in a further specific embodiment, the second portion may have a cylindrical shape, may have a second length (L2), and may include a second end window. In particular, in an embodiment, 0.7 ≤ L2 / L < 1 may apply. In a specific embodiment, the axicon-shaped optical element may be configured to receive at least a portion of the first device light via the first portion and provide an annular beam of the first device light to the light emitter via the second portion. In a specific embodiment, the axicon-shaped optical element may also be configured to collect at least a portion of the luminescent material light via the second portion and provide a beam of the luminescent material light via the first portion. Accordingly, the present invention particularly provides a light generation system comprising a first light generation device, a light emitter, a heat conducting element, and an axicon-shaped optical element; wherein: (A) the first light generation device is configured to generate first device light; the first light generation device includes one or more of a superluminescent diode and a solid-state laser; (B) the light emitter includes a luminescent material configured to convert at least a portion of the first device light into luminescent material light; the light emitter has an annular shape; (C) the heat conducting element (a) is configured to be in thermal contact with at least a portion of the light emitter, and (b) is reflective for one or more of the first device light and the luminescent material light; (D) the axicon-shaped optical element includes a first portion and a second portion and has an optical element length (L); the first portion has a conical shape, a first length (L1), and includes a first end window; the second portion has a cylindrical shape, a second length (L2), and includes a second end window; where 0.7 ≤ L2 / L < 1; and (E) the axicon-shaped optical element is configured to: (a) receive at least a portion of the first device light via the first portion and provide an annular beam of the first device light to the light emitter via the second portion, and (b) collect at least a portion of the luminescent material light via the second portion and provide a beam of the luminescent material light via the first portion.

[0007] With such a system it may be possible to provide light with a relatively high intensity. Furthermore, with such a system it may be possible to use a high intensity light source to pump the luminescent material. Moreover, such a system may be relatively compact. In an embodiment, it may also be possible to provide white (system) light with such a system.

[0008] As indicated above, the present invention provides a light generating system comprising a first light generating device, a light emitter, a thermally conductive element and an axicon shaped optical element. These will be described below.

[0009] The light generating device may in particular be configured to generate device light. In particular, the light generating device may comprise a light source. The light source may in particular be configured to generate light source light. In embodiments, the device light may consist essentially of light source light. In other embodiments, the device light may consist essentially of converted light source light. In still other embodiments, the device light may comprise (unconverted) light source light and converted light source light. The light source light may be converted with a luminescent material into luminescent material light and / or with an upconverter into upconverted light (see also below). The term "light generating device" may also refer to a plurality of light generating devices that may provide device light having substantially the same spectral power distribution. In specific embodiments, the term "light generating device" may also refer to a plurality of light generating devices that may provide device light having different spectral power distributions.

[0010] The term "light source" can in principle relate to any light source known in the art. It can be a conventional (tungsten) bulb, a low-pressure mercury lamp, a high-pressure mercury lamp, a fluorescent lamp, an LED (light emitting diode). In a specific embodiment, the light source comprises a solid-state LED light source (such as an LED or a laser diode (or "diode laser")). The term "light source" can also relate to a plurality of light sources, such as 2 to 2000 (solid-state) LED light sources. Therefore, the term LED can also refer to a plurality of LEDs. In addition, the term "light source" can also refer to a so-called chip-on-board (COB) light source in an embodiment. The term "COB" refers in particular to an LED chip in the form of a semiconductor chip, which is neither encapsulated nor connected, but is directly mounted on a substrate such as a PCB. Therefore, a plurality of light-emitting semiconductor light sources can be configured on the same substrate. In an embodiment, a COB is a multi-LED chip configured together as a single lighting module.

[0011] The term "light source" may also refer to a chip scale package (CSP). A CSP may include a single solid-state die on which a layer including a luminescent material is provided. The term "light source" may also refer to a medium power package. A medium power package may include one or more solid-state dies. (One or more) dies may be covered by a layer including a luminescent material. The die size may be equal to or less than 2 mm, such as in the range of, for example, 0.2 mm to 2 mm. Therefore, in an embodiment, the light source includes a solid-state light source. In addition, in a specific embodiment, the light source includes a chip scale package LED. In this article, the term "light source" may also particularly refer to a small solid-state light source, such as having a mini size or a micro size. For example, the light source may include one or more of a mini LED and a micro LED. In particular, in an embodiment, the light source includes a micro LED or "microLED" or "μLED". In this article, the term mini size or mini LED particularly indicates a solid-state light source having a size (such as a die size, particularly a length and a width) selected from a range of 100 μm to 1 mm. In this context, the term μ-size or micro-LED particularly denotes a solid-state light source having dimensions, such as die dimensions, particularly length and width, selected from the range of 100 μm and smaller.

[0012] The light source may have a light escape surface. With reference to conventional light sources such as light bulbs or fluorescent lamps, it may be the outer surface of a glass or quartz housing. For an LED, it may be, for example, an LED die, or, when a resin is applied to an LED die, it may be the outer surface of a resin. In principle, it may also be the end of an optical fiber. The term escape surface particularly relates to that part of the light source where light actually leaves the light source or escapes from the light source. The light source is configured to provide a light beam. The light beam (therefore) escapes from the light exit surface of the light source.

[0013] Likewise, the light generating device may comprise a light escape surface, such as an end window. Furthermore, also, the light generating system may comprise a light escape surface, such as an end window.

[0014] The term "light source" may refer to a semiconductor light emitting device, such as a light emitting diode (LED), a resonant cavity light emitting diode (RCLED), a vertical cavity laser diode (VCSEL), an edge emitting laser, etc. The term "light source" may also refer to an organic light emitting diode (OLED), such as a passive matrix (PMOLED) or an active matrix (AMOLED). In a specific embodiment, the light source includes a solid-state light source (such as an LED or a laser diode). In one embodiment, the light source includes an LED (light emitting diode). The term "light source" or "solid-state light source" may also refer to a superluminescent diode (SLED).

[0015] The term LED may also refer to a plurality of LEDs.

[0016] The term "light source" may also relate to a plurality of (substantially identical (or different)) light sources, such as 2-2000 solid-state light sources. In an embodiment, the light source may comprise one or more micro-optical elements (an array of micro-lenses) located downstream of a single solid-state light source (such as an LED) or downstream of a plurality of solid-state light sources (i.e., for example, shared by a plurality of LEDs). In an embodiment, the light source may comprise an LED with on-chip optics. In an embodiment, the light source comprises a pixelated single LED (with or without optics) (in an embodiment providing on-chip beam steering).

[0017] In an embodiment, the light source may be configured to provide a primary radiation that is used as is, such as, for example, a blue light source like a blue LED, or a green light source such as a green LED, and a red light source such as a red LED. Such LEDs that may not include a luminescent material ("phosphor") may be indicated as direct color LEDs.

[0018] However, in other embodiments, the light source may be configured to provide primary radiation, and a portion of the primary radiation is converted into secondary radiation. The secondary radiation may be based on a conversion performed by a luminescent material. Therefore, the secondary radiation may also be indicated as luminescent material radiation. In an embodiment, the luminescent material may be included by a light source, such as an LED having a luminescent material layer or a dome including a luminescent material. Such an LED may be indicated as a phosphor-converted LED or a PC LED (phosphor-converted LED). In other embodiments, the luminescent material may be configured at a certain distance from ("away from") the light source, such as an LED having a luminescent material layer that is not in physical contact with the die of the LED. Therefore, in a specific embodiment, the light source may be a light source that emits at least light at a wavelength selected from the range of 380nm to 470nm during operation. However, other wavelengths may also be possible. The light may be partially converted by the luminescent material.

[0019] In an embodiment, the light generating device may comprise a luminescent material. In an embodiment, the light generating device may comprise a PCLED. In other embodiments, the light generating device may comprise a direct LED (i.e., without phosphor). In an embodiment, the light generating device may comprise a laser device, like a laser diode. In an embodiment, the light generating device may comprise a super luminescent diode. Thus, in a specific embodiment, the light source may be selected from the group of a laser diode and a super luminescent diode. In other embodiments, the light source may comprise an LED.

[0020] The light source may in particular be configured to generate a source light having an optical axis (O) (, beam shape) and a spectral power distribution. In an embodiment, the source light may comprise one or more bands having a bandwidth as known for lasers.

[0021] The term "light source" may (thus) refer to the light generating element itself, like for example a solid-state light source; or for example to the packaging of a light generating element (such as a solid-state light source) and one or more of the following: an element comprising a luminescent material and (other) optics, like lenses, collimators. A light converter element ("converter element" or "converter") may comprise an element comprising a luminescent material. For example, a solid-state light source like a blue LED is itself a light source. A combination of a solid-state light source (as a light generating element) and a light converter element (such as a blue LED and a light converter element) optically coupled to the solid-state light source may also be a light source (but may also be indicated as a light generating device). Thus, a white LED is a light source (but may also be indicated as a (white) light generating device, for example).

[0022] The term "light source" herein may also refer to light sources including solid state light sources, such as LEDs or laser diodes or super luminescent diodes.

[0023] In embodiments, the term "light source" may (therefore) also refer to a light source that is (also) based on conversion of light, such as a light source in combination with a luminescent converter material. Thus, the term "light source" may also refer to a combination of an LED and a luminescent material configured to convert at least a portion of the LED radiation, or a combination of a (diode) laser and a luminescent material configured to convert at least a portion of the (diode) laser radiation.

[0024] In an embodiment, the term "light source" may also refer to a combination of a light source (like an LED) and a filter that may change the spectral power distribution of the light generated by the light source. In particular, the term "light generating device" may be used to address a light source and additional things (optical components), like filters and / or beam shaping elements, etc.

[0025] The phrase "different light sources" or "multiple different light sources" and similar phrases may refer to multiple solid-state light sources selected from at least two different bins in embodiments. Similarly, the phrase "same light source" or "multiple same light sources" and similar phrases may refer to multiple solid-state light sources selected from the same bin in embodiments.

[0026] The terms "solid-state light source" or "solid-state material light source" and similar terms may particularly refer to semiconductor light sources, such as light emitting diodes (LEDs), diode lasers or superluminescent diodes.

[0027] The term "laser light source" particularly refers to a laser. Such a laser may particularly be configured to generate laser light source light having one or more wavelengths in the UV, visible or infrared, particularly having a wavelength selected from the spectral wavelength range 200nm-2000nm, such as 300nm-1500nm. The term "laser" particularly refers to a device that emits light by an optical amplification process based on stimulated emission of electromagnetic radiation.

[0028] In particular, in embodiments, the term "laser" may refer to a solid-state laser. In specific embodiments, the term "laser" or "laser light source" or similar terms refer to a laser diode (or diode laser).

[0029] Thus, in an embodiment, the light source comprises a laser light source. In an embodiment, the term "laser" or "solid-state laser" or "solid-state material laser" may refer to one or more of the following: cerium-doped lithium strontium (or calcium) aluminum fluoride (Ce:LiSAF, Ce:LiCAF), chromium-doped chrysoberyl (alexandrite) laser, chromium ZnSe (Cr:ZnSe) laser, divalent samarium-doped calcium fluoride (Sm:CaF2) laser, Er:YAG laser, erbium-doped and co-doped erbium-ytterbium laser. glass lasers, F center lasers, holmium YAG (Ho:YAG) lasers, Nd:YAG lasers, NdCrYAG lasers, Nd:YCa4O(BO3)3 or Nd:YCOB doped with neodymium, Nd:YVO4 lasers, neodymium glass (Nd:glass) lasers, neodymium YLF (Nd:YLF) solid-state lasers, promethium 147-doped phosphate glass (147Pm 3+ : glass) solid-state laser, ruby ​​laser (Al2O3:Cr 3+ ), Thulium YAG (Tm:YAG) laser, Titanium Sapphire (Ti: Sapphire; Al2O3:Ti 3+ ) lasers, calcium fluoride doped with trivalent uranium (U:CaF2) solid-state lasers, ytterbium-doped glass lasers (rods, plates / chips and optical fibers), ytterbium YAG (Yb:YAG) lasers, Yb2O3 (glass or ceramic) lasers, etc.

[0030] For example, including second and third harmonic generation embodiments, the light source may include one or more of the following: a F-centered laser, a yttrium orthovanadate (Nd:YVO4) laser, a promethium-147-doped phosphate glass (147Pm 3+ : glass), and titanium sapphire (Ti: sapphire; Al2O3:Ti 3+ ) laser. For example, taking into account the second and third harmonic generation, such a light source can be used to generate blue light.

[0031] In an embodiment, the term "laser" or "solid-state laser" or "solid-state material laser" may refer to one or more of the following: semiconductor laser diodes (such as GaN, InGaN, AlGaInP, AlGaAs, InGaAsP), lead salts, vertical cavity surface emitting lasers (VCSEL), quantum cascade lasers, hybrid silicon lasers, etc.

[0032] Lasers can be combined with upconverters to obtain shorter (laser) wavelengths. For example, upconversion can be obtained using some (trivalent) rare earth ions, or upconversion can be obtained using nonlinear crystals. Alternatively, lasers can be combined with downconverters (such as dye lasers) to obtain longer (laser) wavelengths.

[0033] As can be derived from the following, the term "laser light source" may also refer to a plurality of (different or identical) laser light sources. In a specific embodiment, the term "laser light source" may refer to a plurality of (N) (identical) laser light sources. In an embodiment, N=2 or more. In a specific embodiment, N may be at least 5, such as in particular at least 8. In this way, a higher brightness can be obtained. In an embodiment, the laser light sources may be arranged in a laser group (see also above). In an embodiment, the laser group may include a heat sink and / or optical devices, such as a lens for collimating the laser. Therefore, in an embodiment, the lasers in a laser group (or "laser array group") may share the same optical devices.

[0034] The laser light source is configured to generate laser light source light (or "laser"). The light source light may essentially consist of laser light source light. The light source light may also comprise laser light source light of two or more (different or identical) laser light sources. For example, laser light source light of two or more (different or identical) laser light sources may be coupled into a light guide to provide a single light beam comprising laser light source light of two or more (different or identical) laser light sources. In a specific embodiment, the light source light is therefore in particular collimated light source light. In yet a further embodiment, the light source light is in particular (collimated) laser light source light.

[0035] In an embodiment, the laser light source light may comprise one or more bands having a bandwidth as known for lasers. In a specific embodiment, the band(s) may be relatively sharp line(s), such as having a full width at half maximum (FWHM) in the range of less than 20 nm (such as equal to or less than 10 nm) at RT. Thus, the light source light has a spectral power distribution (intensity on an energy scale as a function of wavelength) that may comprise one or more (narrow) bands.

[0036] The beam (of the light source light) may be a focused or collimated beam of the (laser) light source light. The term "focused" may particularly refer to converging to a small spot. The small spot may be at a discrete converter region, or (slightly) upstream thereof or (slightly) downstream thereof. In particular, the focusing and / or collimation may be such that the cross-sectional shape (perpendicular to the optical axis) of the light beam at (at the side) the discrete converter region is substantially not larger than the cross-sectional shape (perpendicular to the optical axis) of the discrete converter region (where the light source light illuminates the discrete converter region). Focusing may be performed using one or more optical devices, such as a (focusing) lens. In particular, two lenses may be applied to focus the laser light source light. Collimation may be performed using one or more (other) optical devices, such as collimating elements, such as lenses and / or parabolic reflectors. In an embodiment, the beam of the (laser) light source light may be relatively highly collimated, such as ≤2° (FWHM) in an embodiment, more particularly ≤1° (FWHM), most particularly ≤0.5° (FWHM). Hence, ≤ 2° (FWHM) can be considered as (highly) collimated source light. Optics can be used to provide (high) collimation (see also above).

[0037] The term "solid-state material laser" and similar terms may refer to: solid-state lasers, such as solid-state lasers based on crystals or glasses doped with ions (such as transition metal ions and / or lanthanide ions); fiber lasers; photonic crystal lasers; semiconductor lasers, such as, for example, vertical cavity surface emitting lasers (VCSELs), etc.

[0038] The term "solid-state light source" and similar terms may particularly refer to semiconductor light sources, such as light emitting diodes (LEDs), diode lasers or super luminescent diodes. Instead of the term "solid-state light source", the term "semiconductor-based light source" may also be applied. Thus, the term "semiconductor-based light source" may, for example, refer to one or more of a light emitting diode (LED), a diode laser and a super luminescent diode.

[0039] Thus, the light generating device may include one or more of a light emitting diode (LED), a diode laser, and a super luminescent diode.

[0040] Superluminescent diodes are known in the art. A superluminescent diode may be indicated as a semiconductor device that may be capable of emitting a broad spectrum of low-coherence light like an LED, while having a brightness on the order of a laser diode.

[0041] For example, US2020192017 indicates that "with current technology, a single SLED can emit with sufficient spectral flatness and sufficient output power in the 800nm-900nm wavelength range, using a bandwidth of, for example, up to 50nm-70nm. In the visible range for display applications, i.e., in the 450nm-650nm wavelength range, with current technology, a single SLED can emit with a bandwidth of up to 10nm-30nm. These emission bandwidths are too small for display or projector applications requiring red (640nm), green (520nm) and blue (450nm) (i.e., RGB) emissions." Furthermore, superluminescent diodes are described, among others, in: “Edge Emitting Laser Diodes and Superluminescent Diodes”, Szymon Stanczyk, Anna Kafar, Dario Schiavon, Stephen Najda, Thomas Slight, Piotr Perlin, book editors: Fabrizio Roccaforte, Mike Leszczynski, first published: August 3, 2020, https: / / doi.org / 10.1002 / 9783527825264.ch9inchapter9.3Superluminescent diodes. The book (and in particular chapter 9.3) is incorporated herein by reference. Among other things, it is indicated that a superluminescent diode (SLD) is an emitter that combines the features of a laser diode and a light emitting diode. SLD emitters utilize stimulated emission, which means that these devices operate at current densities similar to those of laser diodes. The main difference between LDs and SLDs is that in the latter case, the device waveguides can be designed in a special way to prevent the formation of standing waves and the generation of lasing. Moreover, the presence of the waveguide ensures the emission of a high-quality beam with high optical spatial coherence, but the light is characterized by having low temporal coherence at the same time, and "Currently, the most successful designs for nitride SLDs are curved, curved or inclined waveguide geometries and inclined facet geometries, and in all cases, the front end of the waveguide intersects the device facet in an oblique angled manner, as shown in Figure 9.10. The oblique angled waveguides suppress reflections of light from the facets to the waveguide by directing the light outside the lossy unpumped region of the device chip." Thus, an SLD may in particular be a semiconductor light source in which the spontaneously emitted light is amplified by stimulated emission in the active region of the device. This emission is called "superluminescence". Superluminescent diodes combine the high power and brightness of laser diodes with the low coherence of conventional light-emitting diodes. The advantage of the low (temporal) coherence of the source is that the speckle is significantly reduced or invisible and the spectral distribution of the emission is much wider than that of laser diodes, which may be better suited for lighting applications. In particular, the spectral power distribution of a superluminescent diode may be varied by varying the current. In this way, the spectral power distribution may be controlled, see also, for example, Abdullah A. Alatawi et al., Optics Express Vol. 26, Issue 20, pp. 26355-26364, https: / / doi.org / 10.1364 / QE.26.026355 .

[0042] As indicated above, the first light generating device may be particularly configured to generate the first device light. Furthermore, the first light generating device may include one or more of a superluminescent diode and a solid-state laser. Thus, the first light generating device may include a light source selected from one or more of a superluminescent diode and a solid-state laser. The solid-state laser may in particular include a diode laser. In an embodiment, the first device light may have one or more wavelengths in the visible wavelengths (i.e., spectral power at one or more wavelengths in the visible wavelength range). In particular, the first device light may include blue light. More particularly, the first device light may be blue light. However, other options are not excluded herein.

[0043] The terms "visible", "visible light" or "visible emission" and similar terms refer to light having one or more wavelengths in the range of about 380nm-780nm. In this document, UV may particularly refer to wavelengths selected from the range of 190nm-380nm, such as 200nm-380nm. The terms "light" and "radiation" are used interchangeably herein, unless it is clear from the context that the term "light" refers only to visible light. Thus, the terms "light" and "radiation" may refer to UV radiation, visible light and IR radiation. In specific embodiments, in particular for lighting applications, the terms "light" and "radiation" refer to (at least) visible light.

[0044] The term "violet light" or "violet emission" and similar terms may particularly relate to light having a wavelength in the range of about 380nm to 440nm. In a specific embodiment, the violet light may have a centroid wavelength in the range of 380nm to 440nm. The term "blue light" or "blue emission" and similar terms may particularly relate to light having a wavelength in the range of about 440nm to 490nm (including some violet and cyan hues). In a specific embodiment, the blue light may have a centroid wavelength in the range of 440nm to 490nm. The term "green light" or "green emission" and similar terms may particularly relate to light having a wavelength in the range of about 490nm to 560nm. In a specific embodiment, the green light may have a centroid wavelength in the range of 490nm to 560nm. The term "yellow light" or "yellow emission" and similar terms may particularly relate to light having a wavelength in the range of about 560nm to 590nm. In a specific embodiment, yellow light may have a centroid wavelength in the range of 560nm to 590nm. The term "orange light" or "orange emission" and similar terms may particularly relate to light having a wavelength in the range of about 590nm to 620nm. In a specific embodiment, orange light may have a centroid wavelength in the range of 590nm to 620nm. The term "red light" or "red emission" and similar terms may particularly relate to light having a wavelength in the range of about 620nm to 750nm. In a specific embodiment, red light may have a centroid wavelength in the range of 620nm to 750nm. The term "cyan light" or "cyan emission" and similar terms may particularly relate to light having a wavelength in the range of about 490nm to 520nm. In a specific embodiment, cyan light may have a centroid wavelength in the range of 490nm to 520nm. The terms "amber light" or "amber emission" and similar terms may particularly relate to light having a wavelength in the range of about 585nm to 605nm, such as about 590nm to 600nm. In a specific embodiment, the amber light may have a centroid wavelength in the range of 585nm to 605nm. The phrase "light having one or more wavelengths in the wavelength range" and similar phrases may particularly indicate that the indicated light (or radiation) has a spectral power distribution that has at least one or more intensities at these one or more wavelengths in the indicated wavelength range. For example, a blue emitting solid-state light source will have a spectral power distribution that has intensities at one or more wavelengths in the wavelength range of 440nm to 495nm.

[0045] Furthermore, the system may comprise a light emitter.Here in the following, first some general aspects concerning the light emitter are described.

[0046] In particular, the luminescent material is comprised by a luminophore. The luminophore may be a layer, such as a self-supporting layer. The luminophore may also include a luminescent coating on a support (in particular a light-transmitting support in a transmission mode, or a reflective support in a reflection mode). In particular, the luminophore may be substantially self-supporting. In an embodiment, the luminescent material may be provided as a luminophore, such as a luminescent single crystal, a luminescent glass or a luminescent ceramic body. Such a "body" may be indicated as a "converter body" or a "luminophore". In an embodiment, the luminophore may be a luminescent single crystal or a luminescent ceramic body. For example, in an embodiment, a garnet luminescent material including cerium may be provided as a luminescent single crystal or as a luminescent ceramic body. In other embodiments, the luminophore may include a light-transmitting body in which a luminescent material is embedded. For example, the luminophore may include a glass body in which a luminescent material is embedded. Alternatively, such glass may be luminescent. In other embodiments, the luminophore may include a polymer body in which a luminescent material is embedded.

[0047] The luminophore can have any shape. However, in general, the luminophore can include two substantially parallel faces, thereby defining the height (of the luminophore). In addition, the luminophore can include an edge face bridging these two substantially parallel faces. The edge face can be curved in one or two dimensions. The edge face can be planar. The luminophore can have a rectangular or circular cross section, although other cross sections may also be possible, such as, for example, hexagonal, octagonal, etc. Therefore, the luminophore can have a circular cross section, an elliptical cross section, a square or a non-square rectangle. In an embodiment, the luminophore can have an n-sided cross section, where n is at least 3, such as 4 (square or rectangular cross section), 5 (pentagonal cross section), 6 (hexagonal cross section), 8 (octagonal cross section) or more. These two substantially parallel faces can also be indicated as "main faces", because they can particularly provide the maximum external area of ​​the luminophore. Perpendicular to the above cross section can be another cross section, which can be rectangular in an embodiment. Thus, the luminous body can, for example, have a cubic shape, a (non-cubic) cuboid shape, an n-sided prism shape (where n is at least 5, such as a pentagonal prism, a hexagonal prism), and a cylindrical shape. However, other shapes may also be possible. In particular, the luminous body can have a cuboid shape, a cylindrical shape or an n-sided prism shape, where n is 6 or 8.

[0048] In an embodiment, the luminophore (or "body") has a lateral dimension width or length (W1 or L1) or diameter (D) and a thickness or height (H1). In an embodiment, (i) D≥H1 or (ii) and W1≥H1 and / or L1≥H1. The luminophore may be transparent or light scattering. In an embodiment, the luminophore may include a ceramic luminescent material. In a specific embodiment, L1≤10mm, such as in particular L1≤5mm, more in particular L1≤3mm, most in particular L1≤2mm. In a specific embodiment, W1≤10mm, such as in particular W1≤5mm, more in particular W1≤3mm, most in particular W1≤2mm. In a specific embodiment, H1≤10mm, such as in particular H1≤5mm, more in particular H1≤3mm, most in particular H1≤2mm. In a specific embodiment, D≤10mm, such as in particular D≤5mm, more in particular D≤3mm, most in particular D≤2mm. In a specific embodiment, the "body" may have a thickness in the range 50μm-1mm in an embodiment. Furthermore, the "body" may have a lateral dimension (width / diameter) in the range 100 μm-10 mm. In yet other specific embodiments, (i) D>H1 or (ii) W1>H1 and L1>H1. In particular, the lateral dimensions such as length, width and diameter are at least 2 times larger than the height, and at least 5 times larger. In a specific embodiment, the luminous body has a first length L1, a first height H1 and a first width W1, wherein H1≤0.5*L1 and H1≤0.5*W1. In an embodiment, the luminous body may be a (small) tile.

[0049] In an embodiment, the light emitter may include a first face, a second face, and a side face bridging the first face and the second face. The first face and the second face may also be indicated as main faces. In the case of a cylindrical shape, the side face may be a single side face. In the case of a cuboid, the side face may include four facets. In the case of a hexagonal prism, the side face may include six facets.

[0050] In a specific embodiment, the light emitter has a ring shape. Thus, in an embodiment, the light emitter may have a hollow cylindrical shape. The hollow cylinder may have a height, which may be substantially constant over the ring, and the height may be substantially independent of the radius. The ring-shaped light emitter may have an inner radius and an outer radius, thereby defining the width of the hollow cylinder. The width may be substantially the same over the entire light emitter. The inner radius and the outer radius may be greater than the height, such as each being at least twice as large as the height.

[0051] Furthermore, the luminophore may in particular comprise a luminescent material. Here below, some embodiments of luminescent materials are described.

[0052] The term "luminescent material" refers in particular to a material which can convert a first radiation, in particular one or more of UV radiation and blue radiation, into a second radiation. Typically, the first radiation and the second radiation have different spectral power distributions. Therefore, instead of the term "luminescent material", the term "luminescent converter" or "converter" may also be applied. Typically, the second radiation has a spectral power distribution at a larger wavelength than the first radiation, which is the case in so-called down-conversion. However, in a specific embodiment, the second radiation has a spectral power distribution with an intensity at a smaller wavelength than the first radiation, which is the case in so-called up-conversion.

[0053] In an embodiment, a "luminescent material" may particularly refer to a material that can convert radiation into, for example, visible light and / or infrared light. For example, in an embodiment, the luminescent material may be able to convert one or more of UV radiation and blue radiation into visible light. In a specific embodiment, the luminescent material may also convert radiation into infrared radiation (IR). Thus, upon excitation with radiation, the luminescent material emits radiation. Typically, the luminescent material will be a down-converter, i.e. radiation of a smaller wavelength is converted into radiation with a larger wavelength (λ ex <λ em ), but in a specific embodiment the luminescent material may comprise an up-converter luminescent material, ie radiation of a larger wavelength is converted into radiation having a smaller wavelength (λ ex >λ em ).

[0054] In an embodiment, the term "luminescence" may refer to phosphorescence. In an embodiment, the term "luminescence" may also refer to fluorescence. Instead of the term "luminescence", the term "emission" may also be applied. Thus, the terms "first radiation" and "second radiation" may refer to excitation radiation and emission (radiation), respectively. Likewise, the term "luminescent material" may refer to phosphorescence and / or fluorescence in an embodiment.

[0055] The term "luminescent material" may also refer to a variety of different luminescent materials. Examples of possible luminescent materials are indicated below. Therefore, the term "luminescent material" may also refer to a luminescent material composition in a specific embodiment. Instead of the term "luminescent material", the term "phosphor" may also be applied. These terms are known to a person skilled in the art.

[0056] In an embodiment, the luminescent material is selected from garnets and nitrides, in particular garnets and nitrides doped with trivalent cerium or divalent europium, respectively. The term "nitride" may also refer to oxynitrides or nitrogen silicates, etc. Alternatively or additionally, the luminescent material(s) may be selected from silicates, in particular silicates doped with divalent europium.

[0057] In a specific embodiment, the luminescent material comprises type A3B5O 12: Ce, wherein in an embodiment, A comprises one or more of Y, La, Gd, Tb and Lu, in particular (at least) one or more of Y, Gd, Tb and Lu, and wherein in an embodiment, B comprises one or more of Al, Ga, In and Sc. In particular, A may comprise one or more of Y, Gd and Lu, such as in particular one or more of Y and Lu. In particular, B may comprise one or more of Al and Ga, more in particular at least Al, such as substantially all Al. Therefore, a particularly suitable luminescent material is a garnet material comprising cerium. An embodiment of garnet in particular comprises A3B5O 12 Garnet, wherein A comprises at least yttrium or lutetium, and wherein B comprises at least aluminum. Such garnet may be doped with cerium (Ce), praseodymium (Pr) or a combination of cerium and praseodymium; however, in particular with Ce. In particular, B may comprise aluminum (Al); however, in addition to aluminum, B may also partially comprise gallium (Ga) and / or scandium (Sc) and / or indium (In), in particular up to about 20% of B, more in particular up to about 10% of B (i.e., the B ions consist essentially of 90% by mole or more of Al and 10% by mole or less of one or more of Ga, Sc and In); B may in particular comprise up to about 10% of gallium. In another variant, B and O may be at least partially replaced by Si and N. The element A may in particular be selected from the group consisting of yttrium (Y), gadolinium (Gd), terbium (Tb) and lutetium (Lu). Furthermore, Gd and / or Tb may in particular be present in an amount only up to about 20% of A. In a specific embodiment, the garnet luminescent material includes (Y 1-x Lu x )3B5O 12 :Ce, wherein x is equal to or greater than 0 and equal to or less than 1. The term ":Ce" indicates that a portion of the metal ions in the luminescent material (i.e., in garnet: a portion of the "A" ions) are replaced by Ce. 1-x Lu x )3Al5O 12 In the case of Ce, part of Y and / or Lu is replaced by Ce. This is known to those skilled in the art. Ce will generally replace A by no more than 10%; usually, the Ce concentration will be in the range of 0.1% to 4%, especially 0.1% to 2% (relative to A). Assuming 1% Ce and 10% Y, the completely correct chemical formula can be (Y 0.1 Lu 0.89 Ce 0.01 )3Al5O 12 As known to those skilled in the art, Ce in garnet is mostly or exclusively in the trivalent state.

[0058] In an embodiment, the luminescent material (therefore) comprises A3B5O 12, wherein in a specific embodiment, up to 10% of B-O can be replaced by Si-N.

[0059] In a specific embodiment, the luminescent material comprises (Y x1-x2-x3 A’ x2 Ce x3 )3(Al y1-y2 B’ y2 )5O 12 , where x1 + x2 + x3 = 1, where x3 > 0, where 0 < x2 + x3 ≤ 0.2, where y1 + y2 = 1, where 0 ≤ y2 ≤ 0.2, where A’ comprises one or more elements selected from the group consisting of lanthanide elements, and where B’ comprises one or more elements selected from the group consisting of Ga, In, and Sc. In an embodiment, x3 is selected from the range of 0.001 - 0.1. In the present invention, particularly x1 > 0, such as > 0.2, like at least 0.8. Garnets having Y can provide a suitable spectral power distribution.

[0060] In a specific embodiment, up to 10% of B-O can be replaced by Si-N. Here, B in B-O refers to one or more of Al, Ga, In, and Sc (and O refers to oxygen); in a specific embodiment, B-O can refer to A1-O. As indicated above, in a specific embodiment, x3 can be selected from the range of 0.001 - 0.04. Particularly, such a luminescent material can have a suitable spectral distribution (however, see below), have a relatively high efficiency, have a relatively high thermal stability, and allow a high CRI (optionally in combination with the light of other light sources as described herein). Thus, in a specific embodiment, A can be selected from the group consisting of Lu and Gd. Alternatively or additionally, B can include Ga. Thus, in an embodiment, the luminescent material comprises (Y x1-x2-x3 (Lu,Gd) x2 Ce x3 )3(Al y1-y2 Ga y2 )5O 12 , where Lu and / or Gd can be available. Even more particularly, x3 is selected from the range of 0.001 - 0.1, where 0 < x2 + x3 ≤ 0.1, and where 0 ≤ y2 ≤ 0.1. Additionally, in a specific embodiment, up to 1% of B-O can be replaced by Si-N. Here, the percentage refers to moles (as known in the art); also see, for example, EP3149108. In still other specific embodiments, the luminescent material comprises (Y x1-x3 Ce x3 )3Al5O 12 , where x1 + x3 = 1, and where 0 < x3 ≤ 0.2, such as 0.001 - 0.1.

[0061] In a specific embodiment, the light generating device may include only a luminescent material selected from garnet-type luminescent materials including cerium. In a further specific embodiment, the light generating device includes a single type of luminescent material, such as (Y x1-x2-x3 A’ x2 Ce x3 )3(Al y1-y2 B’ y2 )5O 12 . Thus, in a specific embodiment, the light generating device includes a luminescent material, wherein at least 85% by weight, even more particularly at least about 90% by weight, such as even more particularly at least about 95% by weight of the luminescent material includes (Y x1-x2-x3 A’ x2 Ce x3 )3(Al y1-y2 B’ y2 )5O 12 . Here, A’ includes one or more elements selected from the group consisting of lanthanide elements, and B’ includes one or more elements selected from the group consisting of Ga, In, and Sc, where x1 + x2 + x3 = 1, where x3 > 0, where 0 < x2 + x3 ≤ 0.2, where y1 + y2 = 1, where 0 ≤ y2 ≤ 0.2. In particular, x3 is selected from the range of 0.001 - 0.1. Note that in an embodiment, x2 = 0. Alternatively or additionally, in an embodiment, y2 = 0.

[0062] In a specific embodiment, A may particularly include at least Y, and B may particularly include at least Al.

[0063] Alternatively or additionally, the luminescent material may include a luminescent material of type A3Si6N 11 :Ce 3+ , where A includes one or more of Y, La, Gd, Tb, and Lu, such as including one or more of La and Y in an embodiment.

[0064] In an embodiment, the luminescent material may alternatively or additionally include one or more of the following: MS:Eu 2+ and / or M2Si5N8:Eu 2+ and / or MAlSiN3:Eu 2+ and / or Ca2AlSi3O2N5:Eu 2+etc., wherein M includes one or more of Ba, Sr and Ca, and in particular includes at least Sr in embodiments. Therefore, in embodiments, the luminescent material may include one or more materials selected from the group consisting of (Ba,Sr,Ca)S:Eu, (Ba,Sr,Ca)AlSiN3:Eu and (Ba,Sr,Ca)2Si5N8:Eu. In these compounds, europium (Eu) is substantially or exclusively divalent and replaces one or more of the indicated divalent cations. Typically, Eu will not be present in an amount greater than 10% of the cations; its presence will in particular be in the range of about 0.5% to 10%, more particularly in the range of about 0.5% to 5%, relative to the (one or more) cations it replaces. The term ":Eu" indicates that a portion of the metal ion is replaced by Eu (in these embodiments by Eu 2+ For example, assuming that CaAlSiN3:Eu contains 2% Eu, the correct chemical formula would be (Ca 0.98 Eu 0.02 )AlSiN3. Divalent europium will generally replace divalent cations, such as the above-mentioned divalent alkaline earth metal cations, in particular Ca, Sr or Ba. The material (Ba,Sr,Ca)S:Eu can also be indicated as MS:Eu, wherein M is one or more elements selected from the group consisting of barium (Ba), strontium (Sr) and calcium (Ca); in particular, M includes calcium or strontium, or calcium and strontium, more in particular calcium in the compound. Here, Eu is introduced and replaces at least a portion of M (i.e. one or more of Ba, Sr and Ca). In addition, the material (Ba,Sr,Ca)2Si5N8:Eu can also be indicated as M2Si5N8:Eu, wherein M is one or more elements selected from the group consisting of barium (Ba), strontium (Sr) and calcium (Ca); in particular, M includes Sr and / or Ba in the compound. In another specific embodiment, M consists of Sr and / or Ba (excluding the presence of Eu), in particular 50% to 100%, more particularly 50% to 90% Ba and 50% to 0%, in particular 50% to 10% Sr, such as Ba 1.5 Sr 0.5Si5N8:Eu (i.e. 75% Ba; 25% Sr). Here, Eu is introduced and replaces at least a portion of M (i.e. one or more of Ba, Sr and Ca). Similarly, the material (Ba, Sr, Ca)AlSiN3:Eu can also be indicated as MAlSiN3:Eu, wherein M is one or more elements selected from the group consisting of barium (Ba), strontium (Sr) and calcium (Ca); in particular, M in the compound includes calcium or strontium, or calcium and strontium, more particularly calcium. Here, Eu is introduced and replaces at least a portion of M (i.e. one or more of Ba, Sr and Ca). As known to those skilled in the art, Eu in the luminescent materials indicated above is generally or only in a divalent state.

[0065] In an embodiment, the red light emitting material may include one or more materials selected from the group consisting of (Ba, Sr, Ca) S: Eu, (Ba, Sr, Ca) AlSiN3: Eu, and (Ba, Sr, Ca) 2Si5N8: Eu. In these compounds, europium (Eu) is substantially or exclusively divalent, and replaces one or more of the indicated divalent cations. In general, Eu will not be present in an amount greater than 10% of the cations; its presence will be particularly in the range of about 0.5% to 10%, more particularly in the range of about 0.5% to 5%, relative to the (one or more) cations it replaces. The term ": Eu" indicates that a portion of the metal ion is replaced by Eu (in these examples, by Eu). 2+ For example, assuming that there is 2% Eu in CaAlSiN3:Eu, the correct chemical formula would be (Ca 0.98 Eu 0.02 )AlSiN 3. The divalent europium will generally replace a divalent cation, such as the above-mentioned divalent alkaline earth metal cations, in particular Ca, Sr or Ba.

[0066] The material (Ba, Sr, Ca) S: Eu may also be indicated as MS: Eu, wherein M is one or more elements selected from the group consisting of barium (Ba), strontium (Sr) and calcium (Ca); in particular, M comprises calcium or strontium, or calcium and strontium, more particularly calcium in the compound. Here, Eu is introduced and replaces at least a portion of M (i.e., one or more of Ba, Sr and Ca).

[0067] Furthermore, the material (Ba, Sr, Ca) 2 Si 5 N 8 : Eu may also be indicated as M 2 Si 5 N 8 : Eu, wherein M is one or more elements selected from the group consisting of barium (Ba), strontium (Sr) and calcium (Ca); in particular, M comprises Sr and / or Ba in the compound. In a further specific embodiment, M consists of Sr and / or Ba (excluding the presence of Eu), in particular 50% to 100% Ba, more particularly 50% to 90% Ba, and 50% to 0% Sr, in particular 50% to 10% Sr, such as Ba. 1.5 Sr 0.5 Si5N8:Eu (ie, 75% Ba; 25% Sr). Here, Eu is introduced and replaces at least a portion of M (ie, one or more of Ba, Sr and Ca).

[0068] Likewise, the material (Ba, Sr, Ca) AlSiN3:Eu may also be indicated as MAlSiN3:Eu, wherein M is one or more elements selected from the group consisting of barium (Ba), strontium (Sr) and calcium (Ca); in particular, M comprises calcium or strontium, or calcium and strontium, more particularly calcium in the compound. Here, Eu is introduced and replaces at least a portion of M (i.e., one or more of Ba, Sr and Ca).

[0069] As known to those skilled in the art, Eu in the above-mentioned luminescent materials is mostly or only in a divalent state.

[0070] The blue light emitting material may include YSO (Y2SiO5:Ce 3+ ) or similar compounds, or BAM (BaMgAl 10 O 17 :Eu 2+ ) or similar compounds.

[0071] The term "luminescent material" in this context particularly relates to inorganic luminescent materials.

[0072] Alternatively or additionally, other luminescent materials may also be applied. For example, quantum dots and / or organic dyes may be applied and may optionally be embedded in a transmissive matrix (like for example a polymer, like PMMA or polysiloxane, etc.).

[0073] Quantum dots are small crystals of semiconductor materials, usually with a width or diameter of only a few nanometers. When excited by incident light, quantum dots emit light whose color is determined by the size and material of the crystal. Therefore, light of a specific color can be produced by adjusting the size of the dots. Most known quantum dots with emission in the visible light range are based on cadmium selenide (CdSe) with a shell, such as cadmium sulfide (CdS) and zinc sulfide (ZnS). Quantum dots without cadmium can also be used, such as indium phosphide (InP) and copper indium sulfide (CuInS2) and / or silver indium sulfide (AgInS2). Quantum dots show very narrow emission bands, and therefore they show saturated colors. In addition, the emission color can be easily tuned by adjusting the size of the quantum dots. Any type of quantum dots known in the art can be used in the present invention. However, for environmental safety and concerns, it may be preferred to use quantum dots without cadmium or at least quantum dots with very low cadmium content.

[0074] Instead of or in addition to quantum dots, other quantum confinement structures may also be used. In the context of the present application, the term "quantum confinement structure" should be understood as, for example, quantum wells, quantum dots, quantum rods, tripods, tetrapods or nanowires.

[0075] Organic phosphors may also be used. Examples of suitable organic phosphor materials are organic luminescent materials based on perylene derivatives, such as those manufactured by BASF as Examples of suitable compounds include, but are not limited to Red F305, Orange F240, Yellow F083 and F 170.

[0076] Different luminescent materials may have different spectral power distributions of the respective luminescent material light. Alternatively or additionally, such different luminescent materials may in particular have different color points (or dominant wavelengths).

[0077] As mentioned above, other luminescent materials are also possible. Therefore, in a specific embodiment, the luminescent material is selected from the group of nitrides containing divalent europium, oxynitrides containing divalent europium, silicates containing divalent europium, garnets containing cerium, and quantum structures. The quantum structure may, for example, include quantum dots or quantum rods (or other quantum type particles) (see above). The quantum structure may also include quantum wells. The quantum structure may also include photonic crystals.

[0078] The luminescent material may be particularly configured to convert at least a portion of the first device light into luminescent material light. The luminescent material light may have one or more wavelengths in the visible wavelengths (i.e., spectral power at one or more wavelengths in the visible wavelength range). In particular, the luminescent material light may include one or more of green light, yellow light, orange light, and red light.

[0079] Thus, in particular, the luminaire may be configured in a light receiving relationship with the light generating device. As indicated below, this may in particular be a light receiving relationship via an axicon-shaped optical element.

[0080] The term "light-receiving relationship" or "light-receiving relationship" and similar terms may indicate that during operation of a light source (like a light generating device or a light generating element or a light generating system), an item may receive light from the light source. Therefore, the item may be configured downstream of the light source. Between the light source and the item, an optical device may be configured. The terms "upstream" and "downstream" may particularly relate to the arrangement of an item or feature relative to the propagation of light from a light generating element (here in particular a light generating device), such as in the context of the propagation of light, wherein relative to a first position in the light beam from the light generating element, a second position in the light beam that is closer to the light generating element (than the first position) is "upstream", and a third position in the light beam that is farther away from the light generating element (than the first position) is "downstream". Instead of the term "light generating element", the term "light generating device" may also be applied.

[0081] Here below, the optical relationship between the light emitter and the axicon shaped optical element is further described. However, first some aspects regarding the thermally conductive element are described.

[0082] The heat conducting element may particularly include a heat conducting material. The heat conducting material may particularly have a thermal conductivity of at least about 20 W / (m*K), such as at least about 30 W / (m*K), such as at least about 100 W / (m*K), such as in particular at least about 200 W / (m*K). In other specific embodiments, the heat conducting material may particularly have a thermal conductivity of at least about 10 W / (m*K). In an embodiment, the heat conducting material may include one or more of the following: copper, aluminum, silver, gold, silicon carbide, aluminum nitride, boron nitride, aluminum silicon carbide, beryllium oxide, silicon carbide composite, aluminum silicon carbide, copper tungsten alloy, copper molybdenum carbide, carbon, diamond and graphite. Alternatively, or additionally, the heat conducting material may include aluminum oxide or be composed of aluminum oxide. In an embodiment, the heat conducting element may include one or more of a heat sink, a heat diffuser and a two-phase cooling device. In still other embodiments, the thermally conductive element may be configured to be in thermal contact with one or more of a heat sink, a heat spreader, and a two-phase cooling device, and may transfer heat to such a heat sink, heat spreader, or two-phase cooling device, for example via another thermally conductive element.

[0083] If an element can exchange energy through a thermal process, the element can be considered to be "thermally in contact" with another element. Therefore, the element can be thermally coupled. In an embodiment, thermal contact can be achieved by physical contact. In an embodiment, thermal contact can be achieved via a thermally conductive material, such as a thermally conductive glue (or thermally conductive adhesive). When two elements are arranged at a distance equal to or less than about 10 μm relative to each other, thermal contact can also be achieved between the two elements, although a larger distance (such as up to 100 μm) may be possible. The shorter the distance, the better the thermal contact. In particular, the distance is 10 μm or less, such as 5 μm or less, such as 1 μm or less. The distance can be the distance between two corresponding surfaces of the corresponding elements. The distance can be an average distance. For example, two elements can be in physical contact at one or more (such as multiple) positions, but at one or more (especially multiple) other positions, the elements are not in physical contact. For example, when one or both elements have a rough surface, this may be the case. Therefore, in an embodiment, on average, the distance between the two elements can be 10 μm or less (although a larger average distance may be possible, such as up to 100 μm). In an embodiment, the two surfaces of two elements can be kept at a certain distance using one or more distance retainers. When two elements are in thermal contact, they can be in physical contact or can be configured at a short distance from each other (like a maximum of 10 μm, such as a maximum of 1 mm). When the two elements are configured at a certain distance from each other, an intermediate material can be configured between them, although in other embodiments, the distance between the two elements can be filled with gas, liquid, or can be a vacuum. When an intermediate material is available, the greater the distance, the higher the thermal conductivity can contribute to the thermal contact between the two elements. However, the smaller the distance, the lower the thermal conductivity of the intermediate material can be (of course, a material with higher thermal conductivity can also be used).

[0084] As indicated above, the thermally conductive element can be configured to be in thermal contact with at least a portion of the luminaire. For example, the luminaire can be configured to be in physical contact with the thermally conductive element. Furthermore, the thermally conductive element can be reflective for one or more of the first device light and the luminescent material light, in particular for both.

[0085] In this document, when an element is indicated as being transmissive, this may mean in embodiments that at one or more wavelengths, the portion of radiation that is transmitted may be greater than the portion of radiation that is reflected or absorbed. In this document, when an element is indicated as being reflective, this may mean in embodiments that at one or more wavelengths, the portion of radiation that is reflected may be greater than the portion of radiation that is transmitted or absorbed. The term "transmissive" with respect to light source light may in this document particularly refer to: at least 50%, such as at least 60%, in particular at least 70%, such as at least 80%, in particular at least 90%, such as at least 95%, of the incident light source light passing through the material under vertical illumination. Similarly, the term "reflective" with respect to light source light may in this document refer to: at least 50%, such as at least 60%, in particular at least 70%, such as at least 80%, in particular at least 90%, such as at least 95% of the incident light source light is reflected under vertical illumination. Here, the percentage may refer to a percentage based on Watts.

[0086] As indicated above, the system may also include an axicon-shaped optical element. An axicon-shaped optical element in particular includes a lens. In other words, the system may include a lens having an axicon-shaped shape. Axicon lenses are known in the art and may, for example, be defined as a special type of lens having a conical surface. An axicon lens may in particular be capable of transforming a laser beam into a ring-shaped distribution (see, for example, http: / / wp.optics.arizona.edu / wp- content / uploads / 2016 / 03 / axicon_Protee p.pdf ). In the present text, the term "axicon-shaped" is used to indicate that small deviations from the axicon shape may also exist. For example, the conical shape may be slightly rounded in embodiments instead of being an essentially pure cone (however, the radius of curvature of the surface of such a rounded conical shape should not be too small, for example it should be larger than the (smallest) diameter of the axicon). Furthermore, in the present text, an axicon-shaped optical element may have a relatively large cylindrical portion. The cylindrical portion may be non-tapered or tapered (see also below).

[0087] In an embodiment, the axicon-shaped optical element comprises a first part and a second part. In particular, the axicon-shaped optical element may have an optical axis. The first part may be configured to be rotationally symmetric with respect to the optical axis, and the second part may be configured to be rotationally symmetric with respect to the optical axis. In particular, the axicon-shaped optical element is a monolithic body of a light-transmitting material (such as quartz, glass, sapphire, a polymer material, etc.), which is essentially composed of the first part and the second part. In addition, the axicon-shaped optical element may have an optical element length (L). In particular, the optical element length may be defined as being parallel to the optical axis. If the axicon-shaped optical element comprises a polymer light-transmitting material, such material may, for example, include one or more of polycarbonate (PC), silicone (polysiloxane), polystyrene, polymethyl methacrylate, etc. In particular, the axicon-shaped optical element may be a solid substantially consisting of a light-transmitting material.

[0088] In particular, the first part may have a conical shape. The conical shape may in particular be a cone. Additionally, the conical shape may have a cone angle selected from the range of about 90° - 178°, more particularly at least about 100°, such as selected from the range of about 105° - 125°. Additionally, the first part may have a first length (L1). In particular, the first length may be defined parallel to the optical axis. Moreover, the first part may include a first end window. The term "end window" may refer to the fact that the end window may be configured at one end of the axicon optical element. Additionally, the term may indicate that light may enter and / or exit particularly via this part of the axicon optical element. In particular, the entire surface of the cone may be the end window. However, this does not necessarily mean that the entire end window is used in this way.

[0089] Furthermore, the second part may have a cylindrical shape. Moreover, this part may have a second length (L2). In particular, the second length may be defined parallel to the optical axis. Additionally, the first part may include a second end window. In particular, the second part may be substantially planar. The term "second end window" may refer to the fact that the end window may be configured at the other end of the axicon optical element. Additionally, the term may indicate that light may enter and / or exit particularly via this part of the axicon optical element. In particular, the entire end surface of the cylinder may be the (second) end window. However, this does not necessarily mean that the entire end window is used in this way.

[0090] Regarding the axicon optical element, the first part and the second part (i.e., substantially the entire axicon optical element) may particularly have a circular cross-section (perpendicular to the optical axis). However, other cross-sectional shapes such as hexagonal, octagonal, decagonal, and more polygonal shapes are not excluded herein.

[0091] The optical element length (L) may be defined by the first end window (in particular the vertex) and the second end window. Thus, in particular L = L1 + L2. Additionally, in particular L1 < L2 herein. More particularly, in an embodiment 0.6 ≤ L2 / L < 1, more particularly 0.7 ≤ L2 / L < 1, such as 0.75 ≤ L2 / L ≤ 0.95. Additionally, in a specific embodiment, 0.8 ≤ L2 / L < 1, more particularly 0.8 ≤ L2 / L ≤ 0.95. In an embodiment, L2 / L may be selected from the range of 0.8 - 0.02. In particular, these shapes and dimensions may allow for the dual function of the axicon optical element, as further described below.

[0092] In particular, the axicon-shaped optical element can be used to project light of a light generating device onto a light-emitting body, but can also be used to collect luminescent material light from the light-emitting body and provide a beam of luminescent material light. Therefore, in an embodiment, the first device light enters via the first end window of the axicon-shaped optical element, but the luminescent material light can also escape from the axicon-shaped optical element via this window. Similarly, the first device light can pass through the second end window of the axicon-shaped optical element after propagating through the axicon-shaped optical element (optionally including (total) internal reflection), but the luminescent material light can also enter the axicon-shaped optical element via the second end window (and propagate through the axicon-shaped optical element (optionally including (total) internal reflection), reach the first end window of the axicon-shaped optical element, and escape via the first end window).

[0093] Therefore, in a specific embodiment, the axicon-shaped optical element can be configured to: (a) receive at least a portion of the first device light via the first part (particularly the first end window), and provide a ring-shaped beam of the first device light to the light-emitting body via the second part (particularly the second end window), and (b) collect at least a portion of the luminescent material light via the second part (particularly the second end window), and provide a beam of the luminescent material light via the first part (particularly the first end window).

[0094] As indicated above, this can provide a relatively compact high intensity light source. In particular, in this way, a ring-shaped phosphor combined with an axicon lens can be provided for producing a laser pumped high intensity light source. As further explained below, in a specific embodiment, this can be a laser pumped high intensity white light source.

[0095] Further embodiments will be described below.

[0096] As indicated above, the cylindrical portion may be non-tapered ("untapered") or tapered (see also below). In particular, in an embodiment, the second portion may taper over at least a portion of the second length (L2) in a direction from the first portion to the second end window. Such taper may be particularly useful with regard to the collimation of the light of the luminescent material. Thus, in an embodiment, the minimum diameter of the axicon-shaped optical element may be defined by the second end window. Thus, in an embodiment, the minimum diameter of the second portion may be the same as the maximum diameter of the first portion (non-tapered), or may be smaller (tapered). In particular, the diameter ratio is not less than 0.5. Thus, in an embodiment, the first end window may have a maximum first window radius (R W1 ), the second end window may have a second window radius (R W2 ), wherein in the embodiment R W2 / R W1 = 1 (non-tapered), or in other embodiments R W2 / R W1<1. In a specific embodiment, 0.5≤R W2 / R W1 ≤0.98. In particular, these shapes and dimensions may allow for dual functionality of the axicon-shaped optical element, as also described further below.

[0097] A non-tapered cylinder may have a constant diameter, and a tapered cylinder or cone may have a decreasing or increasing diameter (increasing or decreasing in its height).

[0098] The light generating system can be particularly configured to generate system light. The system light can include at least a portion of the luminescent material light that has escaped from the first end window. This luminescent material light can be in particular non-white light (see also above). For white light applications, it may be desirable to provide one or more light sources that can contribute to the system light and provide white light with a desired correlated color temperature (CCT) and / or a desired color rendering index (CRI). Several technical solutions appear to be possible, such as using a light source that bypasses the optical element and the luminescent material. However, the pump light itself can also be used as a component of the system light. This can be particularly the case when a portion of the first device light is reflected at the light emitter and enters the axicon-shaped optical element again via the second end window. The light emitted from the first end window can then include both a portion of the first device light and the luminescent material light. By selecting the radius of the light emitter and the axicon-shaped optical element, the portion of the first device light that can be reflected only at the thermally conductive element and can substantially not interact with the light emitter can be controlled.

[0099] In an embodiment, in the range of 0%-35%, such as in the range of about 2%-35%, like in the range of 2%-30%, the spectral power of the first device light escaping from the second end window can be reflected at the thermal conductor without any interaction with the light emitter or after being transmitted through the light emitter (i.e., propagating twice the optical path length), and arrive at the second end window again as unconverted and reflected first device light. Here, the percentage refers to the percentage relative to this spectral power in Watts. In an embodiment, up to about 70% (i.e., a maximum of 70% of 35% (35% or 30%, respectively)) of it can have no interaction with the light emitter at all, such as up to about 50%. Therefore, in an embodiment, the light generating system can be configured so that a portion of the first device light escaping from the second end window can be reflected at one or more of the thermally conductive element and the light emitter, enter the axicon-shaped optical element via the second end window after reflection, and escape from the axicon-shaped optical element via the first end window together with at least a portion of the luminescent material light to provide a light beam including the first device light and the luminescent material light. Therefore, the system light can include at least a portion of the first device light and at least a portion of the luminescent material light. In this way, the light generating system can be used to provide white system light, optionally in combination with one or more additional light sources.

[0100] The light escaping from the first end window and the first device light illuminating the first end window may have substantially parallel optical axes. Therefore, in an embodiment, the optical element that guides the first device light into the first part and / or the optical element that guides the luminescent material light away from the optical axis of the axicon-shaped optical element may be relatively small and / or have a dichroic function compared to the light beam of the luminescent material light escaping from the first end window. The former technical solution may be useful when the reflected first device light may also have to propagate together with the luminescent material light and be part of the system light. The latter technical solution may be useful when such a first device light is not desired. A combination of these technical solutions may also be applied. Such an optical device is also indicated as a "first optical device" in this article.

[0101] Thus, in an embodiment, the system may include an optional first optical device. In an embodiment, the first optical device may be configured in an optical path of the first device light between the first light generating device and the first end window. The first optical device may be configured to reflect the first device light so that after reflection it illuminates the first end window with the first device light. In such an embodiment, the first optical device may include a reflector or a dichroic mirror, wherein the latter is transmissive for the luminescent material light and reflective for the first device light. In an alternative embodiment not further discussed herein, the first optical device may include a dichroic mirror, which is reflective for the luminescent material light and transmissive for the first device light.

[0102] In an embodiment, the first end window has a maximum first window circular cross section (A w1 ). In addition, as indicated above, the optional first optical device may include a reflector. In a specific embodiment, the reflector may include a dichroic mirror (reflective for the first device light and transmissive for the luminescent material light) in a specific embodiment. The reflector (such as a dichroic mirror in an embodiment) may have an optical device cross section (A o1 ), the optical device cross section is defined as parallel to the largest first window circular cross section (A w1 ). In particular, A o1 / A w1 ≤0.5. In this way, the light beam of the luminescent material light may not be intercepted too much by the reflector. In an embodiment, 0.01≤A o1 / A w1 ≤0.5. However, other values ​​may also be possible. When the reflector is at a larger distance from the axicon optical element, even values ​​greater than 0.5 may be possible. However, this may be less desirable when a smaller size system is desired.

[0103] It seems useful when the first device light does not completely illuminate the first end window, but only partially surrounds the optical axis of the axicon-shaped optical element. In an embodiment, the first light generating device and the optional first optical device are configured to provide a pump beam with a circular cross section (A) at the first end window. p ) of the first device light beam. In addition, in an embodiment, the first end window has a maximum first window circular cross section (A w1 ). In particular, in embodiment A p / A w1 ≤0.8.

[0104] As indicated above, the light emitter may be configured to be in thermal contact with the thermal conductor (see also further below). In a specific embodiment, the light emitter may also be configured to be in thermal contact with the axicon-shaped optical element. Thus, the following options may essentially exist: (a) the light emitter and the axicon-shaped optical element are not in optical contact and not in thermal contact, (b) they are in thermal contact, but not in optical contact, (c) they are in both thermal and optical contact, but not in physical contact, and (d) they are in thermal contact, optical contact, and physical contact.

[0105] Thermal contact has been described above. When the elements are optically in contact or optically coupled, they may be in physical contact with each other in embodiments, or in other embodiments may be separated from each other by, for example, a (thin) layer of optical material, such as an optical glue or other optically transparent interface material (e.g. having a thickness of less than about 1 mm, preferably less than 100 μm). When no optically transparent interface material is applied, the (average) distance between two elements in optical contact may be, in particular, approximately at most the relevant wavelength, such as the wavelength of the emission maximum. For visible wavelengths, this may be less than 1 μm, such as less than 0.7 μm, and for blue, even smaller. Therefore, when optical coupling is desired, an optically transparent interface material may be applied. In yet other embodiments, when no optically transparent interface material is applied, the average distance between two elements in optical contact may be, in particular, approximately at most the relevant wavelength, such as the wavelength of the emission maximum. Therefore, when optical contact is desired, physical contact may exist. However, even in such an embodiment, there may be a non-zero average distance, but then the non-zero average distance is equal to or below the wavelength of interest, such as about 700 nm, or even below about 470 nm (e.g., taking into account the use of reflected first device light).

[0106] In a specific embodiment, the first distance (d1) between the light emitter and the second end window can be selected from the range of 0-0.1*L. In other specific embodiments, the distance can be at least not greater than 100 μm. In other embodiments, the distance can be not greater than about 0.7 μm, such as not greater than about 0.5 μm. Therefore, in a specific embodiment, the light emitter and the second end window can be configured to be in optical contact (and therefore the distance can be not greater than about 0.7 μm, such as not greater than about 0.5 μm).

[0107] For reasons of efficiency, it appears to be useful when the end window has a diameter (or radius) that is (slightly) larger than the largest diameter (or radius) of the emitter. In particular, the emitter has an outer emitter radius (R Lo ) and the inner radius of the luminous body (R Li In addition, in particular, the second end window has a second window radius (R w2 As will be clear to those skilled in the art, in particular R Lo >R Li In addition, in the embodiment 0.7≤R Lo / R w2 ≤1.05, more particularly 0.80≤R Lo / R w2 ≤1. In particular, in the embodiment 0.85≤R Lo / R w2 ≤1, more particularly 0.85≤R Lo / Rw2 <1, such as 0.85≤R Lo / R w2 ≤0.99.

[0108] In particular, the luminous body may have a first face pointing to the second end window, a side face and a bottom face configured to be farthest from the second end window. In an embodiment, at least the bottom face may be at least partially in thermal contact with the heat-conducting element. More particularly, in an embodiment, the side face and the bottom face may be configured to be in thermal contact with the heat-conducting element. This may be the case, for example, when the heat-conducting element may include a slit in which the luminous body may be at least partially accommodated. Thus, in an embodiment, the heat-conducting element may include an annular slit accommodating at least a portion of the luminous body, wherein in particular the side face and the bottom face may be configured to be in thermal contact with the heat-conducting element. One or both side faces may be in thermal contact over a portion of their height, or may be in thermal contact over the entire height.

[0109] Thus, in a particular embodiment, the thermal conductor may include an annular slit having a shape (and size) corresponding to the annular light emitter.

[0110] In a specific embodiment, the luminescent material may include type A3B5O 12 :Ce, wherein A may include one or more of Y, La, Gd, Tb and Lu, and wherein B may include one or more of Al, Ga, In and Sc (see also further above). In particular, such a luminescent material may be stable at high pump powers. As indicated above, the term "luminescent material" may also refer in embodiments to a combination of two or more different luminescent materials.

[0111] In a specific embodiment, the luminous body may include a ceramic body. Due to the relatively high thermal conductivity, such as, for example, a body including type A3B50 12 Ceramic bodies of luminescent materials containing Ce can be particularly useful in thermal management.

[0112] In a specific embodiment, the first light generating device may include a blue (laser) light emitting diode laser.

[0113] As indicated above, the system light may include luminescent material light, optionally including first device light. It may be desirable that the optical properties of this light are further adjusted and / or (more) controllable in terms of CRI, CCT and color point. For this purpose, one or more further light generating devices (indicated as "second light generating devices") may be applied.

[0114] Such a second light generating device may in particular be neither configured to provide a second light that must propagate through the axicon-shaped optical element nor to interact with (including being transmitted and / or reflected by) a light emitter, although none of these options are excluded herein.

[0115] Furthermore, one or more second light generating devices may be configured to provide a second device light having substantially the same spectral power distribution as the first device light, but such one or more second light generating devices may be configured to bypass their second device light from the light emitter. Such one or more second light generating devices may be used to control the ratio of pump light (particularly blue light) to luminescent material light in the system light. For this purpose, the system may also include a control system (also see further below).

[0116] Alternatively or additionally, one or more (other) second light generating devices may be configured to provide a second device light having a spectral power distribution substantially different from the first device light. Moreover, such one or more (other) second light generating devices may be configured to cause their second device light to bypass the light emitter. Such one or more (other) second light generating devices may be used to control the ratio of second device light to luminescent material light in the system light. For this purpose, the system may also include a control system (also see further below).

[0117] In both ways, CCT, CRI and color point can be further tuned and / or controlled.

[0118] The device light from one or more second light generating devices can be mixed with the luminescent material light (and optional (unconverted) first device light) using a beam combiner. Therefore, in a specific embodiment, the light generating system may also include a beam combiner and a second light generating device. The second light generating device may be configured to generate a second device light. The beam combiner may be configured to combine the first luminescent material light, the optional first device light, and the second device light downstream of the first end window. In a specific embodiment, the second light generating device may be configured to generate a second device light having a second spectral power distribution that is different from the first spectral power distribution of the first device light. In particular, in an embodiment, the second device light may have an intensity in the orange-red wavelength range (i.e., in the wavelength range of 590nm-750nm).

[0119] In a specific embodiment, in an operable mode of the light generating system, the system light may be white light. The white light may be based on one or more of the first device light and the second device light and the luminescent material light.

[0120] The term "white light" and similar terms herein are known to the person skilled in the art. It may particularly relate to light having a correlated color temperature (CCT) between about 1800K and 20000K, such as between 2000K and 20000K, in particular 2700K to 20000K, for general lighting, in particular in the range of about 2000K to 7000K, such as in the range of 2700K to 6500K. In an embodiment, for example for backlighting purposes or for other purposes, the correlated color temperature (CCT) may in particular be in the range of about 7000K to 20000K. And further, in an embodiment, the correlated color temperature (CCT) is in particular within about 15SDCM (color matching standard deviation) from the BBL (black body locus), in particular within about 10SDCM from the BBL, even more in particular within about 5SDCM from the BBL.

[0121] In a specific embodiment, the correlated color temperature (CCT) may be selected from the range of 6000 K to 12000 K, such as from the range of 7000 K to 12000 K, such as at least 8000 K. And further, in an embodiment, in combination with a CRI of at least 70, the correlated color temperature (CCT) may be selected from the range of 6000 K to 12000 K, such as from the range of 7000 K to 12000 K.

[0122] As indicated above, in a specific embodiment, the system may also include a control system (or the system may be functionally coupled to a control system). The control system may be configured to control the system light, more particularly its optical properties. The control system may control the system light by controlling one or more first light generating devices and one or more second light generating devices.

[0123] The term "control" and similar terms refer at least in particular to the behavior of determining an element or the operation of a regulatory element. Therefore, "control" and similar terms herein may, for example, refer to the application of behavior (determining the behavior of an element or the operation of a regulatory element) to an element, such as, for example, measuring, displaying, actuating, opening, moving, changing temperature, etc. In addition, the term "control" and similar terms may additionally include monitoring. Therefore, the term "control" and similar terms may include applying behavior to an element, and also include applying behavior to an element and monitoring the element. The control of an element may be accomplished using a control system, which may also be indicated as a "controller". The control system and the element may therefore be functionally coupled at least temporarily or permanently. The element may include a control system. In an embodiment, the control system and the element may not be physically coupled. Control may be accomplished via wired and / or wireless control. The term "control system" may also refer to a plurality of different control systems, which are particularly functionally coupled, and wherein, for example, one control system may be a master control system, and one or more other control systems may be slave control systems. The control system may include a user interface or may be functionally coupled to a user interface.

[0124] The control system may also be configured to receive and execute instructions from a remote control. In an embodiment, the control system may be controlled via an application (App) on a device, such as a portable device, such as a smart phone or I-phone, a tablet, etc. Therefore, the device is not necessarily coupled to the lighting system, but may be (temporarily) functionally coupled to the lighting system.

[0125] Thus, in an embodiment, the control system may (also) be configured to be controlled by an application on a remote device. In such an embodiment, the control system of the lighting system may be a slave control system or a control in slave mode. For example, the lighting system may be identified with a code, which code is in particular a unique code of the respective lighting system. The control system of the lighting system may be configured to be controlled by an external control system, which accesses the lighting system based on knowledge of the (unique) code (entered via a user interface with an optical sensor (e.g. a QR code reader)). The lighting system may also comprise means for communicating with other systems or devices, such as based on Bluetooth, Thread, WIFI, LiFi, ZigBee, BLE or WiMAX or another wireless technology.

[0126] A system or device or apparatus may perform actions in a "mode" or "operating mode" or "operable mode". The term "operable mode" may also be indicated as a "control mode". Similarly, in a method, actions or phases or steps may be performed in a "mode" or "operating mode" or "operable mode". This does not exclude that a system or device or apparatus may also be adapted to provide another control mode, or a plurality of other control modes. Similarly, this may not exclude that one or more other modes may be performed before and / or after the execution of the mode.

[0127] However, in an embodiment, a control system adapted to provide at least a control mode may be available. If other modes are available, the selection of such modes may in particular be performed via a user interface, but other options (such as performing modes depending on sensor signals or (time) schemes) are also possible. In an embodiment, an operating mode may also refer to a system or device or apparatus that can only be operated in a single operating mode (i.e. "on", without further tunability).

[0128] Therefore, in an embodiment, the control system may perform control according to one or more of an input signal of a user interface, a sensor signal (of a sensor) and a timer. The term "timer" may refer to a clock and / or a predetermined time scheme.

[0129] For example, the light generating system may be part of or may be applied in an office lighting system, a home application system, a shop lighting system, a household lighting system, an accent lighting system, a spotlighting system, a theatre lighting system, a fibre optic application system, a projection system, a self-lighting display system, a pixelated display system, a segmented display system, a warning sign system, a medical lighting application system, an indicator sign system, a decorative lighting system, a portable system, a motor vehicle application, a (outdoor) road lighting system, a city lighting system, a greenhouse lighting system, horticultural lighting, digital projection or LCD backlighting. The light generating system (or luminaire) may be part of or may be applied in, for example, an optical communication system or a disinfection system.

[0130] In yet another aspect, the present invention also provides a lamp or a lamp fixture comprising a light generating system as defined herein. The lamp fixture may also include a housing, an optical element, a shutter, etc. ... The lamp or lamp fixture may also include a housing surrounding the light generating system. The lamp or lamp fixture may include a light window or a housing opening in the housing, through which the system light may escape from the housing. In yet another aspect, the present invention also provides a projection device comprising a light generating system as defined herein. In particular, a projection device or "projector" or "image projector" may be an optical device that projects an image (or moving image) onto a surface such as, for example, a projection screen. The projection device may include one or more light generating systems such as described herein. Therefore, in one aspect, the present invention also provides a light generating device selected from the group of lamps, lamps, projector devices, disinfection devices, photochemical reactors, and optical wireless communication devices, the light generating device including a light generating system as defined herein. The light generating device may include a housing or a carrier configured to accommodate or support one or more elements of the light generating system. For example, in an embodiment, the light generating device may include a housing or carrier configured to accommodate or support one or more of: one or more first light generating devices, an axicon-shaped optical element, a thermally conductive element, and optionally one or more second light generating devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0131] Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference numerals indicate corresponding parts and in which:

[0132] Figures 1a to 1d schematically depict some embodiments and aspects; and

[0133] Figure 2 Some application embodiments are schematically depicted.

[0134] Schematic diagrams are not necessarily to scale. DETAILED DESCRIPTION

[0135] 1 a to 1 d schematically depict embodiments and aspects regarding (an embodiment of) a light generating system 1000 comprising a first light generating device 110 , a light emitter 1200 , a thermally conductive element 500 and an axicon-shaped optical element 400 .

[0136] The first light generating device 110 may be configured to generate a first device light 111. The first light generating device 110 may include one or more of a superluminescent diode and a solid-state laser.

[0137] The luminaire 1200 may include a luminescent material 200 configured to convert at least a portion of the first device light 111 into luminescent material light 201. The luminaire 1200 may have a ring shape (see also Fig. 1 b).

[0138] The thermally conductive element 500 may optionally include an annular slit 510 that accommodates at least a portion of the luminaire 1200. The thermally conductive element 500 may be reflective to one or more of the first device light 111 and the luminescent material light 201.

[0139] Axicon-shaped optical element 400 may include a first portion 410 and a second portion 420, and have an optical element length L. First portion 410 may have a conical shape, a first length L1, and may include a first end window 411. Second portion 420 may have a cylindrical shape, a second length L2, and may include a second end window 422. In an embodiment, 0.7≤L2 / L<1.

[0140] The axicon-shaped optical element 400 may be configured to: (a) receive at least a portion of the first device light 111 via the first window portion 410, and provide a ring-shaped beam of the first device light 111 to the light-emitting body 1200 via the second window portion 420, and (b) collect at least a portion of the luminescent material light 201 via the second window portion 420, and provide a beam of the luminescent material light 201 via the first window portion 410.

[0141] In an embodiment, the second portion 420 may be tapered over at least a portion of the second length L2 in a direction from the first portion 410 to the second end window 422 .

[0142] The first end window 411 may have a maximum first window radius (Rw1), and the second end window 422 may have a second window radius (R w2 ). In the embodiment, 0.5≤R W2 / R W1 ≤0.98. In addition, in the embodiment, 0.8≤L2 / L<1.

[0143] The light generating system 1000 can be configured so that a portion of the first device light 111 escaping from the second end window 422 can be reflected at one or more of the thermal conductive element 500 and the light emitting body 1200, enter the axicon-shaped optical element 400 via the second end window 422 after reflection, and escape from the axicon-shaped optical element 400 via the first end window 411 together with at least a portion of the luminescent material light 201 to provide a light beam including the first device light 111 and the luminescent material light 201.

[0144] The first end window 411 may have a maximum first window circular cross section A w1The optional first optical device 610 may include a reflector 611, such as a dichroic mirror 612 in a specific embodiment. The optional first optical device may have an optical device cross section A o1 , optical device cross section A o1 is defined as parallel to the circular cross section A of the pump beam p and the maximum first window circular cross section A w1 In an embodiment, A o1 / A w1 ≤0.5.

[0145] In an embodiment, the first light generating device 110 and the optional first optical device 610 may be configured to provide a pump beam having a circular cross section A at the first end window 411. p In addition, the first end window 411 may have a maximum first window circular cross section A w1 In an embodiment, A p / A w1 ≤0.8.

[0146] In a specific embodiment, the first distance d1 between the illuminator 1200 and the second end window 422 may be selected from the range of 0-0.1*L. In Fig. 1a, d1 is substantially zero, while in Fig. 1c, an embodiment in which d1 is not zero is schematically depicted.

[0147] In a specific embodiment, and referring to, for example, Figures 1a and 1c, the luminaire 1200 and the second end window 422 can be configured to be in optical contact.

[0148] 1a to 1d, the light emitter 1200 may have an outer light emitter radius R Lo and the inner radius R of the luminous body Li The second end window 422 may have a second window radius R W2 In particular, R Lo >R Li In addition, in a specific embodiment, 0.85≤R Lo / R w2 <1.

[0149] The luminaire 1200 may have a first face 1201 pointing toward the second end window 422, a side face 1202, and a bottom face 1203 configured to be farthest from the second end window 422. In a specific embodiment, the bottom face 1203 and optionally the side face 1202 may be configured to be in thermal contact with the thermally conductive element 500.

[0150] In an embodiment, the thermally conductive element 500 may be selected from the group consisting of a heat sink, a heat spreader, and a two-phase cooling device.

[0151] In an embodiment, the luminescent material 200 may include type A3B5O 12 : Ce, wherein A may include one or more of Y, La, Gd, Tb and Lu, and wherein B may include one or more of Al, Ga, In and Sc. In a specific embodiment, the luminous body 1200 may include a ceramic body.

[0152] In an embodiment, the first light generating device 110 may include a blue (laser) light emitting diode laser.

[0153] In an embodiment, the light generating system 1000 may further include a beam combiner 620 and a second light generating device 120. The second light generating device 120 may be configured to generate a second device light 121 having a second spectral power distribution different from the first spectral power distribution of the first device light 111, or the spectral power distribution may be substantially the same. In a specific embodiment, the second spectral power distribution is different from the first spectral power distribution of the first device light 111, and in particular, the second device light 121 has an intensity in the orange-red wavelength range. The beam combiner 620 may be configured to combine the first luminescent material light 201 and the second device light 121 (and optionally the first device light 111) downstream of the first end window 411. The light generating system 1000 may be configured to generate a system light 1001, which includes at least a portion of the following: the combined first luminescent material light 201, the first device light 111, and the second device light 121.

[0154] In an operational mode of the light generating system 1000 , the system light 1001 may be white light.

[0155] Figure 2An embodiment of a luminaire 2 comprising a light generating system 1000 as described above is schematically depicted. Reference numeral 301 indicates a user interface, which may be functionally coupled with a control system 300, which is comprised by or functionally coupled to the light generating system 1000. FIG. 3 further schematically depicts an embodiment of a lamp 1 comprising a light generating system 1000. Reference numeral 3 indicates a projector device or a projector system, which may be used, for example, to project an image at a wall, which may also comprise the light generating system 1000. Thus, FIG. 3 schematically depicts an embodiment of a lighting device 1200, which is selected from the group of a lamp 1, a luminaire 2, a projector device 3, a disinfection device, a photochemical reactor and an optical wireless communication device, which comprises a light generating system 1000 as described herein. In an embodiment, such a lighting device may be a lamp 1, a luminaire 2, a projector device 3, a disinfection device or an optical wireless communication device. The lighting device light escaping from the lighting device 1200 is indicated with reference numeral 1201. The lighting device light 1201 may essentially consist of the system light 1001 and may therefore be the system light 1001 in a specific embodiment. Reference numeral 1300 refers to a space, such as a room. Reference numeral 1305 refers to the floor and reference numeral 1310 refers to the ceiling; reference numeral 1307 refers to the wall.

[0156] In an embodiment, in one configuration, the phosphor disk is attached to a reflective heat sink, and heat is removed through the back and sides of the phosphor tile.When such a disk is illuminated by a pump laser, a hot spot forms in the center of the disk, which limits the achievable power density.

[0157] In particular, it is proposed herein to use a ring-shaped phosphor to increase the contact area with the heat sink and thus prevent overheating of the phosphor by cooling the phosphor not only from the top and bottom surfaces but also from the sides. The ring-shaped phosphor can be illuminated with a ring-shaped pump beam created using an axicon optical element. The emitted light is then collected using the same axicon.

[0158] In the simulations performed, there was a small air gap between the axicon and the phosphor. However, the axicon could also be placed directly on top of the phosphor surface for additional cooling and to reduce reflections.

[0159] The axicon can be composed of a tapered cylindrical rod with a conical top surface. With a specific value of the cone top angle, the hollow ring-shaped pump beam can effectively illuminate the ring phosphor. It is proposed in this paper to use the same axicon optical element to collect the converted light as well as the unconverted blue pump light. The tapered shape is expected to provide mixing and "pre-collimation" of the converted phosphor light and the reflected blue light.

[0160] In particular, a small dichroic mirror is used to couple blue pump light into the axicon, although a small reflector may also be applied. A portion of the blue pump light may be reflected from the phosphor and from the portion of the heat sink that may not be covered by the phosphor. The blue reflection of the heat sink may be designed to give a good white balance of the total output.

[0161] Referring to FIG. 1d , it can be seen that light can be efficiently guided onto the phosphor.

[0162] Based on modeling, it can be concluded that the axicon that projects a ring-shaped blue light pattern onto the phosphor collects the light emitted by the axicon phosphor and produces a circular light beam.

[0163] In Table 1 below, some of the results for various axicon-phosphor combinations are presented. It can be seen that as expected, as the phosphor area increases, the FWHM also increases:

[0164]

[0165] The term "plurality" refers to two or more.

[0166] Those skilled in the art will understand the terms "substantially" or "essentially" and similar terms herein. The terms "substantially" or "essentially" may also include embodiments with "all", "completely", "all", etc. Therefore, in embodiments, the adjectives substantially or substantially may also be removed. Where applicable, the term "substantially" or the term "essentially" may also relate to 90% or higher, such as 95% or higher, in particular 99% or higher, even more in particular 99.5% or higher, including 100%.

[0167] The term "comprising" also includes embodiments wherein the term "comprising" means "consisting of.

[0168] The term "and / or" particularly relates to one or more of the items mentioned before and after "and / or". For example, the phrase "item 1 and / or item 2" and similar phrases may relate to one or more of item 1 and item 2. The term "comprising" may refer to "consisting of" in one embodiment, but may also refer to "including at least the specified species and optionally one or more other species" in another embodiment.

[0169] In addition, the terms first, second, third, etc. in the specification and claims are used to distinguish similar elements and not necessarily to describe a sequential or chronological order. It should be understood that the terms so used are interchangeable under appropriate circumstances, and that the embodiments of the invention described herein are capable of operation in other sequences than those described or illustrated herein.

[0170] Among other things, an apparatus, device or system may be described herein during operation. It will be clear to one skilled in the art that the present invention is not limited to methods of operation, or apparatus, devices or systems in operation.

[0171] It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims.

[0172] In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

[0173] The use of the verb "comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. Unless the context clearly requires otherwise, throughout the specification and claims, the words "comprises," "comprising," etc. should be interpreted in an inclusive sense, rather than an exclusive or exhaustive sense; that is, in the sense of "including but not limited to."

[0174] The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

[0175] The invention can be implemented by means of hardware comprising several distinct elements and by means of a suitably programmed computer. In an apparatus claim, or a device claim or a system claim, several means are enumerated, several of which may be embodied by the same item of hardware. The simple fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. In a further aspect, the invention (therefore) provides a software product which, when run on a computer, is capable of implementing (one or more embodiments of) the method as described herein.

[0176] The present invention also provides a control system that can control a device, apparatus or system, or can perform a method or process described herein. Still further, the present invention also provides a computer program product that, when functionally coupled to a device, apparatus or system or run on a computer included in the device, apparatus or system, controls one or more controllable elements of such a device, apparatus or system.

[0177] The present invention also applies to a device, an apparatus or a system comprising one or more of the characterizing features described in the specification and / or shown in the drawings. The present invention also relates to a method or a process comprising one or more of the characterizing features described in the specification and / or shown in the drawings.

[0178] The various aspects discussed in this patent can be combined to provide additional advantages. In addition, those skilled in the art will appreciate that the embodiments can be combined, and more than two embodiments can also be combined. In addition, some of the features can form the basis of one or more divisional applications.

Claims

1. A light generation system (1000) comprising a first light generation device (110), a light emitter (1200), a heat conducting element (500), and an axicon optical element (400); wherein: The first light generation device (110) is configured to generate first device light (111); the first light generation device (110) includes one or more of a superluminescent diode and a solid state laser; The light emitter (1200) includes a luminescent material (200) configured to convert at least a portion of the first device light (111) into luminescent material light (201); the light emitter (1200) has an annular shape; The heat conducting element (500) is (a) configured to be in thermal contact with at least a portion of the light emitter (1200), and (b) reflective to one or more of the first device light (111) and the luminescent material light (201); The axicon optical element (400) includes a first portion (410) and a second portion (420), and has an optical element length (L); the first portion (410) has a conical shape, a first length (L1), and includes a first end window (411); the second portion (420) has a cylindrical shape, a second length (L2), and includes a second end window (422); where 0.7 ≤ L2 / L < 1; and The axicon optical element (400) is configured to: (a) receive at least a portion of the first device light (111) via the first portion (410) and provide an annular beam of the first device light (111) to the light emitter (1200) via the second portion (420), and (b) collect at least a portion of the luminescent material light (201) via the second portion (420) and provide a beam of the luminescent material light (201) via the first portion (410).

2. The light generation system (1000) according to claim 1, wherein the second portion (420) tapers over at least a portion of the second length (L2) in a direction from the first portion (410) to the second end window (422).

3. The light generating system (1000) according to claim 2, wherein the first end window (411) has a maximum first window radius (R W1 ), wherein the second end window (422) has a second window radius (R W2 ), where 0.5≤R W2 / R W1 ≤0.98; and 0.8≤L2 / L <l。 4. The light generation system (1000) according to any one of the preceding claims, wherein the light generation system (1000) is configured such that a portion of the first device light (111) escaping from the second end window (422) is reflected at one or more of the heat conducting element (500) and the light emitter (1200), and after reflection enters the axicon optical element (400) via the second end window (422) and exits the axicon optical element (400) via the first end window (411) together with at least a portion of the luminescent material light (201) to provide a beam including the first device light (111) and the luminescent material light (201).

5. The light generating system (1000) according to any one of the preceding claims, further comprising a first optical device (610); wherein the first end window (411) has a maximum first window circular cross section (A w1 ); wherein the first optical device (610) includes a dichroic mirror (612) having an optical device cross section (A o1 ), the optical device cross section (A o1 ) is defined as being parallel to the largest first window circular cross section (A w1 ), where A o1 / A w1 ≤0.

5.

6. The light generating system (1000) according to claim 5, wherein the first light generating device (110) and the first optical device (610) are configured to provide a pump beam having a circular cross section (A) at the first end window (411). p ) of a first device light (111); wherein the first end window (411) has a maximum first window circular cross-section (A) as defined in claim 5 w1 ), where A p / A w1 ≤0.

8.

7. The light generating system (1000) according to any of the preceding claims, wherein a first distance (d1) between the light emitter (1200) and the second end window (422) is selected from the range of 0-0.1*L.

8. The light generating system (1000) according to any one of the preceding claims, wherein the light emitter (1200) and the second end window (422) are configured to be in optical contact, wherein the light emitter (1200) has an outer light emitter radius (R Lo ) and the inner radius of the luminous body (R Li ), wherein the second end window (422) has a second window radius (R w2 ), where R Lo >R Li , and where 0.85≤R Lo / R W2 <1.

9. A light generating system (1000) according to any one of the preceding claims, wherein the thermally conductive element (500)(a) comprises an annular slit (510) for accommodating at least a portion of the light emitting body (1200), wherein the light emitting body (1200) has a first surface (1201) pointing toward the second end window (422), a side surface (1202), and a bottom surface (1203) configured to be farthest from the second end window (422), wherein the side surface (1202) and the bottom surface (1203) are configured to be in thermal contact with the thermally conductive element (500).

10. The light generating system (1000) according to any of the preceding claims, wherein the thermally conductive element (500) is selected from the group consisting of a heat sink, a heat spreader and a two-phase cooling device.

11. The light generating system (1000) according to any one of the preceding claims, wherein the luminescent material (200) comprises a luminescent material of type A3B50. 12 :Ce light-emitting material, wherein A includes one or more of Y, La, Gd, Tb and Lu, and wherein B includes one or more of Al, Ga, In and Sc.

12. The light generating system (1000) according to any of the preceding claims, wherein the light emitting body (1200) comprises a ceramic body.

13. The light generating system (1000) according to any of the preceding claims, wherein the first light generating device (110) comprises a blue light emitting diode laser.

14. The light generating system (1000) according to any one of the preceding claims, further comprising a beam combiner (620) and a second light generating device (120), wherein the second light generating device (120) is configured to generate a second device light (121), the second device light having a second spectral power distribution different from the first spectral power distribution of the first device light (111); wherein the second device light (121) has an intensity in the orange-red wavelength range; wherein the beam combiner (620) is configured to combine the second device light (121) and the first luminescent material light (201) downstream of the first end window (411); wherein the light generating system (1000) is configured to generate system light (1001), the system light comprising at least a portion of: the combined first luminescent material light (201), the first device light (111) and the second device light (121); wherein in an operable mode of the light generating system (1000), the system light (1001) is white light.

15. A lighting device (1200) selected from the group of a lamp (1), a lamp fixture (2), a projector device (3), a disinfection device, a photochemical reactor and an optical wireless communication device, the lighting device (1200) comprising a light generating system (1000) according to any one of the preceding claims.

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