Annular phosphor combined with axicon lens to produce laser-pumped high-intensity white light source

Abstract

The present invention provides a light-generation system (1000) including a first light-generation device (110), a luminescent body (1200), a thermally conductive element (500), and an axicon-like optical element (400), wherein: (A) the first light-generation device (110) is configured to generate first device light (111), the first light-generation device (110) including one or more of a superluminescent diode and a solid-state laser; (B) the luminescent body ( (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 luminescent body (1200) having an annular shape; and (C) a thermally conductive element (500) configured (a) to be in thermal contact with at least a portion of the luminescent body (1200), and (b) to convert at least one of the first device light (111) and the luminescent material light (201). (D) the axicon-like optical element (400) comprises a first portion (410) and a second portion (420) and has an optical element length (L), the first portion (410) having a conical shape, a first length (L1) and comprising a first end window (411), the second portion (420) having a cylindrical shape, a second length (L2) and comprising a second end window (422), where 0.7≦L2 / L<1; (E) the axicon-like optical element (400) comprises: (a) a first portion (410) and a second portion (420) and having an optical element length (L), the first portion (410) having a conical shape, a first length (L1) and comprising a first end window (411), the second portion (420) having a cylindrical shape, a second length (L2) and comprising a second end window (422), where 0.7≦L2 / L<1; A light generating system is provided that is configured to (a) receive at least a portion of a first device light (111) via a portion (410) and provide an annular beam of the first device light (111) to a luminescent body (1200) via a second portion (420), and (b) collect at least a portion of a luminescent material light (201) via the second portion (420) and provide a beam of luminescent material light (201) via the first portion (410).

Description

[Technical Field]

[0001] The present invention relates to a light-generating system and to a light-generating device including such a light-generating system. [Background technology]

[0002] Solid-state lighting is known in the art. For example, US Pat. No. 7,165,871 B2 describes a light-generating lamp including a semiconductor light-emitting element that generates light, a fluorescent material spaced apart from the semiconductor light-emitting element, a first optical element that focuses light generated by the semiconductor light-emitting element onto the fluorescent material, and a second optical element having an optical center at the position where the fluorescent material is located and emitting light from the fluorescent material based on the light focused by the first optical element toward the exterior of the lamp. The lamp is used as a vehicle headlamp, and the second optical element emits light from the fluorescent material toward the exterior of the lamp so as to form at least a portion of a cut line that defines the boundary between the bright and dark areas of the headlamp. This document further describes a combination of a laser, a phosphor, and a reflector integrated into a light-emitting module used for automotive front lights. Summary of the Invention [Problem to be solved by the invention]

[0003] Laser-based light sources have attracted much interest due to their potential to generate relatively high luminous flux from a relatively small emitting area. The high brightness of these light sources may facilitate more precise control of light distribution through optics and miniaturization. Furthermore, it may be desirable to have a high-brightness light source for general lighting applications that is tunable over a wide range of color space / CCT with good color rendering. Typically, to achieve color tunability, a combination of several light sources with different starting color points (e.g., various light sources with different phosphors, different primary colors (e.g., RGB) from direct emitters, or a combination thereof) may be required. To create a high-brightness, color-tunable light source, these multiple light sources may need to be optically combined with good color mixing and without further increase in etendue. However, for systems with direct RGB lasers, optical combination of multiple light sources often results in a relatively low CRI unless there is an unrealistic primary laser wavelength requirement, e.g., due to the inherent narrow spectral width of the laser line and / or due to practical limitations, e.g., to a certain limited spectral range. Furthermore, for systems with two or more phosphor converters, the etendue tends to increase significantly (such as by at least a factor of x2), 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 rather than requiring specialized equipment.

[0004] There appears to be a need for lighting devices that can be relatively compact and / or that can provide relatively high intensities. Furthermore, it appears desirable for such lighting devices to have adequate thermal management so that such high light intensities can be made possible by using high intensity pump light sources, such as lasers. [Means for solving the problem]

[0005] It is therefore an aspect of the present invention to provide an alternative light-generating system (and / or lighting device (including such a light-generating system)), which preferably also at least partially obviates one or more of the above-mentioned disadvantages. The present invention may have the aim of overcoming or ameliorating at least one of the disadvantages of the prior art, or of providing a useful alternative.

[0006] According to a first aspect, the present invention provides a light-generation system ("system") including a first light-generating device, a luminescent body, a thermally conductive element, and an axicon-like optical element. In particular, the first light-generating device is configured to generate first device light. In certain embodiments, the first light-generating device may include one or more of a superluminescent diode and a solid-state laser. Further, in particular, the luminescent body includes a luminescent material that may be configured to convert at least a portion of the first device light into luminescent material light. In certain embodiments, the luminescent body may have an annular shape. In certain embodiments, the thermally conductive element may be configured to be in thermal contact with at least a portion of the luminescent body. In certain embodiments, the thermally conductive element may be reflective to one or more of the first device light and the luminescent material light. In certain embodiments, the axicon-like optical element may include a first portion and a second portion and may have an optical element length (L). In more specific embodiments, the first portion may have a conical shape, a first length (L1), and may include a first end window. Furthermore, in more specific embodiments, the second portion may have a cylindrical shape, a second length (L2), and may include a second end window. In particular, in some embodiments, 0.7≦L2 / L<1 may apply. In certain embodiments, the axicon-like optical element may be configured to receive at least a portion of the first device light through the first portion and to provide an annular beam of the first device light to the luminescent body through the second portion. In certain embodiments, the axicon-like optical element may also be configured to collect at least a portion of the luminescent material light through the second portion and to provide a beam of luminescent material light through the first portion.Therefore, the present invention relates, inter alia, to a light-generation system including a first light-generating device, a luminescent body, a thermally conductive element, and an axicon-like optical element, wherein: (A) the first light-generating device is configured to generate first device light, the first light-generating device comprising one or more of a superluminescent diode and a solid-state laser; (B) the luminescent body comprises a luminescent material configured to convert at least a portion of the first device light into luminescent material light, the luminescent body having an annular shape; and (C) the thermally conductive element is configured (a) to be in thermal contact with at least a portion of the luminescent body, and (b) to convert at least one of the first device light and the luminescent material light into luminescent material light. (D) the axicon-like optical element includes a first portion and a second portion and has an optical element length (L), wherein the first portion is conical, has a first length (L1), and includes a first end window, and the second portion is cylindrical, has a second length (L2), and includes a second end window, wherein 0.7≦L2 / L<1; (E) the axicon-like optical element is configured to (a) receive at least a portion of first device light through the first portion and provide an annular beam of first device light to a luminescent body through the second portion, and (b) collect at least a portion of the luminescent material light through the second portion and provide a beam of luminescent material light through the first portion.

[0007] Such systems may be capable of providing light having a relatively high intensity. Further, such systems may be capable of using a high-intensity light source to pump the luminescent material. Further, such systems may be relatively compact. In some embodiments, such systems may also be capable of providing white (system) light.

[0008] As mentioned above, the present invention provides a light-generating system including a first light-generating device, a luminescent body, a thermally conductive element, and an axicon-like optical element, which are described below.

[0009] The light-generating device may be configured, among other things, to generate device light. In particular, the light-generating device may include a light source. The light source may be configured, among other things, to generate source light. In certain embodiments, the device light may consist essentially of source light. In other embodiments, the device light may consist essentially of converted source light. In still other embodiments, the device light may include (unconverted) source light and converted source light. The source light may be converted to luminescent material light with a luminescent material and / or converted to upconverted light with an upconverter (see also below). The term "light-generating device" may also refer to multiple light-generating devices capable of providing device light having essentially the same spectral power distribution. In certain embodiments, the term "light-generating device" may also refer to multiple light-generating devices capable of providing device light having different spectral power distributions.

[0010] The term "light source" may in principle refer to any light source known in the art. It may be a conventional (tungsten) lamp, a low-pressure mercury lamp, a high-pressure mercury lamp, a fluorescent lamp, or an LED (light-emitting diode). In certain embodiments, the light source includes a solid-state LED light source (such as an LED or a laser diode (or "diode laser")). The term "light source" may also refer to a plurality of light sources, such as 2 to 2000 (solid-state) LED light sources. Thus, the term LED may also refer to a plurality of LEDs. Furthermore, the term "light source" may also refer in certain embodiments to so-called chip-on-board (COB) light sources. The term "COB" particularly refers to an LED chip in the form of a semiconductor chip that is not packaged or connected but is directly mounted on a substrate, such as a PCB. Thus, several light-emitting semiconductor light sources may be configured on the same substrate. In certain embodiments, the 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 die having a layer containing a luminescent material disposed thereon. The term "light source" may also refer to a mid-power package. A mid-power package may include one or more solid die. The die may be covered by a layer containing a luminescent material. The die dimensions may be 2 mm or less, for example, in the range of 0.2 to 2 mm. Thus, in some embodiments, the light source includes a solid-state light source. Furthermore, in certain embodiments, the light source includes a chip scale packaged LED. Here, the term "light source" may also refer to a small solid-state light source, particularly one having a mini or micro size. For example, the light source may include one or more of a mini LED and a micro LED. In particular, in some embodiments, the light source includes a plurality of micro LEDs, "micro LEDs," or "μLEDs." Here, the term mini size or mini LED particularly denotes a solid-state light source having dimensions, e.g., die dimensions, in particular length and width, selected from the range of 100 μm to 1 mm, and here, the term μ size or micro LED particularly denotes a solid-state light source having dimensions, e.g., die dimensions, in particular length and width, selected from the range of 100 μm or less.

[0012] The light source may have a light escape surface. For conventional light sources such as light bulbs or fluorescent lamps, the light escape surface may be the outer surface of the glass or quartz envelope. For LEDs, the light escape surface may for example be the LED die or the outer surface of the resin if the resin is applied to the LED die. In principle, the light escape surface may also be the end of a fiber. The term escape surface particularly relates to the part of the light source where the light actually leaves (escapes) the light source. The light source is configured to provide a light beam. This light beam (thus) escapes from the light source's light exit surface.

[0013] Similarly, the light-generating device may include a light-escape surface, such as an end window.Furthermore, similarly, the light-generating system may include 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), or an edge-emitting laser. The term "light source" may also refer to an organic light-emitting diode (OLED), such as a passive-matrix (PMOLED) or active-matrix (AMOLED). In certain embodiments, the light source comprises a solid-state light source (such as an LED or laser diode). In one embodiment, the light source comprises 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 multiple LEDs.

[0016] The term "light source" may also refer to multiple (essentially identical (or different)) light sources, such as 2 to 2000 solid-state light sources. In some embodiments, the light source may include one or more micro-optical elements (an array of microlenses) downstream of a single solid-state light source, such as an LED, or downstream of multiple solid-state light sources (i.e., shared, for example, by multiple LEDs). In some embodiments, the light source may include an LED with on-chip optics. In some embodiments, the light source includes a pixelated single LED (with or without optics) (which, in some embodiments, provides on-chip beam steering).

[0017] In some embodiments, the light source may be configured to provide primary radiation for use as such, e.g., a blue light source, such as 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, which may not include a luminescent material ("phosphor"), may be referred to as direct color LEDs.

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

[0019] In some embodiments, the light-generating device may include a luminescent material. In some embodiments, the light-generating device may include a PC LED. In other embodiments, the light-generating device may include a direct LED (i.e., no phosphor). In some embodiments, the light-generating device may include a laser device, such as a laser diode. In some embodiments, the light-generating device may include a superluminescent diode. Thus, in certain embodiments, the light source may be selected from the group of laser diodes and superluminescent diodes. In other embodiments, the light source may include an LED.

[0020] The light source may be configured to generate a source light having, among other things, an optical axis (O), a beam shape (), and a spectral power distribution, which in some embodiments may have one or more bands, with bandwidths as known for lasers.

[0021] The term "light source" may thus refer to the light-generating element itself, such as a solid-state light source, or to a package of one or more of a light-generating element, such as a solid-state light source, and an element containing a luminescent material and (other) optics, such as a lens, a collimator, etc. A light-converting element ("converter element" or "converter") may include an element containing a luminescent material. A solid-state light source itself, such as a blue LED, is a light source. A combination of a solid-state light source (as a light-generating element) and a light-converting element optically coupled to the solid-state light source, such as a blue LED and a light-converting element, may also be a light source (but may be referred to as a light-generating device). Thus, a white LED is a light source (but may be referred to as a (white) light-generating device, for example).

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

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

[0024] In some embodiments, the term "light source" may also refer to a combination of a light source, such as an LED, and an optical 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 cover a light source and additional optical components, such as optical filters and / or beam-shaping elements.

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

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

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

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

[0029] Thus, in some embodiments, the light source comprises a laser light source. In some embodiments, the term "laser" or "solid state laser" or "solid state material laser" may be used. The term "cerium-doped lithium strontium (or calcium) aluminum fluoride (Ce:LiSAF, Ce:LiCAF), chromium-doped chrysoberyl (alexandrite) lasers, chromium ZnSe (Cr:ZnSe) lasers, divalent samarium-doped calcium fluoride (Sm:CaF2) lasers, Er:YAG lasers, erbium-doped and erbium-ytterbium co-doped glass lasers, F-center lasers, holmium YAG (Ho:YAG) lasers, Nd:YAG lasers, NdCrYAG lasers, neodymium-doped yttrium calcium oxoborate Nd:YCa4O(BO3)3 or Nd:YCOB, neodymium-doped yttrium orthovanadate (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, trivalent uranium-doped calcium fluoride (U:CaF2) solid-state lasers, ytterbium-doped glass lasers (rod, plate / chip, and fiber), ytterbium YAG (Yb:YAG) lasers, Yb2O3 (glass or ceramics) lasers, etc.

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

[0031] In some embodiments, the terms "laser" or "solid state laser" or "solid state material laser" may refer to one or more of semiconductor laser diodes, such as GaN, InGaN, AlGaInP, AlGaAs, InGaAsP, lead salt, vertical cavity surface emitting laser (VCSEL), quantum cascade laser, hybrid silicon laser, etc.

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

[0033] As can be derived from the following, the term "laser source" may also refer to a plurality of (different or identical) laser sources. In certain embodiments, the term "laser source" may refer to a plurality of N (identical) laser sources. In certain embodiments, N=2 or more. In certain embodiments, N may be at least 5, in particular at least 8. In this way, higher brightness may be obtained. In certain embodiments, the laser sources may be arranged in a laser bank (see also above). A laser bank may, in certain embodiments, include a heat sink and / or optics, e.g., a lens for collimating the laser light. Thus, in certain embodiments, the lasers in a laser bank (or "laser array bank") may share the same optics.

[0034] The laser light source is configured to generate laser source light (or "laser light"). The source light may consist essentially of laser source light. The source light may also include laser source light of two or more (different or the same) laser sources. For example, laser source light of two or more (different or the same) laser sources may be coupled into a light guide to provide a single light beam including the laser source light of the two or more (different or the same) laser sources. Thus, in certain embodiments, the source light is, in particular, collimated source light. In yet other embodiments, the source light is, in particular, (collimated) laser source light.

[0035] The laser source light may, in some embodiments, include one or more bands having a bandwidth as known for lasers. In certain embodiments, the bands may be relatively sharp lines, such as those having a full width half maximum (FWHM) at room temperature (RT) in the range of less than 20 nm, such as 10 nm or less. Thus, the source light has a spectral power distribution (intensity in energy scale as a function of wavelength) that may include one or more (narrow) bands.

[0036] The (source light) beam may be a focused or collimated beam of (laser) source light. The term "focused" may in particular refer to converging to a small spot. This small spot may be at a discrete converter region, or (slightly) upstream or (slightly) downstream of the discrete converter region. In particular, the focusing and / or collimation may be such that the cross-sectional shape (perpendicular to the optical axis) of the beam at a discrete converter region (at the side) is not essentially larger than the cross-sectional shape (perpendicular to the optical axis) of the discrete converter region (where the source light illuminates the discrete converter region). The focusing may be performed with one or more optics, such as a (focusing) lens. In particular, two lenses may be applied to focus laser source light. The collimation may be performed with one or more (other) optics, such as a collimating element, such as a lens and / or a parabolic mirror. In some embodiments, the beam of (laser) source light may be relatively highly collimated, such as in some embodiments ≦2° (FWHM), more particularly ≦1° (FWHM), and most particularly ≦0.5° (FWHM). Thus, ≦2° (FWHM) may be considered as (highly) collimated source light. Optics may be used to provide the (high) collimation (see also above).

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

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

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

[0040] Superluminescent diodes are known in the art and may be described as semiconductor devices that potentially can emit broad-spectrum, low-coherence light like an LED, while having brightness comparable to that of a laser diode.

[0041] US2020192017, for example, indicates that "with current technology, a single SLED can emit light over a bandwidth of, for example, at most 50 to 70 nm in the wavelength range of 800 to 900 nm with sufficient spectral flatness and sufficient power. In the visible range used for display applications, i.e., the wavelength range of 450 to 650 nm, a single SLED can emit light over a bandwidth of at most 10 to 30 nm with current technology. These emission bandwidths are too small for display or projector applications requiring red (640 nm), green (520 nm), and blue (450 nm), i.e., RGB, emission." Furthermore, superluminescent diodes are described, inter alia, in Chapter 9.3, "Superluminescent Diodes," of "Edge Emitting Laser Diodes and Superluminescent Diodes," https: / / doi.org / 10.1002 / 9783527825264.ch9, first published on August 3, 2020, by authors Szymon Stanczyk, Anna Kafar, Dario Schiavon, Stephen Najda, Thomas Slight, and Piotr Perlin, and edited by Fabrizio Roccaforte and Mike Leszczynski. This book, and particularly Chapter 9.3, is incorporated herein by reference. The book, inter alia, describes superluminescent diodes (SLDs) as emitters that combine the characteristics of laser diodes and light-emitting diodes. 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 waveguide may be designed in a special way to prevent the formation of standing waves and lasing. Nevertheless, the presence of the waveguide ensures the emission of a high-quality light beam with high spatial coherence, but the light is simultaneously characterized by low temporal coherence.Currently, the most successful designs for nitride SLDs involve bent, curved, or tilted waveguide geometries and tilted facet geometries. In all cases, the front end of the waveguide meets the device facet at an angle, as shown in Figure 9.10. The tilted waveguide reduces light reflection by redirecting light from the facet into the waveguide and outward into the lossy unpumped area of ​​the device chip. Therefore, SLDs can be used as semiconductor light sources, particularly those in which spontaneous emission is amplified by stimulated emission in the active region of the device. This type of 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 low (temporal) coherence of the light source has the advantage that speckle is significantly reduced or invisible, and the spectral distribution of the emission is much broader than that of laser diodes, potentially making them more suitable for lighting applications. In particular, by changing the current, the spectral power distribution of the superluminescent diode can be changed, and in this way the spectral power distribution can be controlled (see, for example, Abdullah A. Alatawi et al., Optics Express Vol. 26, Issue 20, pp. 26355-26364, https: / / doi.org / 10.1364 / OE.26.026355).

[0042] As described above, the first light-generating device may be configured to generate a first device light. Furthermore, the first light-generating device may include one or more of a superluminescent diode and a solid-state laser. Therefore, 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 include a diode laser. In some embodiments, the first device light may have one or more wavelengths in the visible range (i.e., spectral power at one or more wavelengths within 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 approximately 380 to 780 nm. As used herein, UV may particularly refer to wavelengths selected from the range of 190 to 380 nm, such as 200 to 380 nm. As used herein, the terms "light" and "radiation" are used interchangeably 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 certain embodiments, particularly for lighting applications, the terms "light" and "radiation" refer to (at least) visible light.

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

[0045] Additionally, the system may include a luminescent body. In the following, we first describe some general aspects regarding luminescent bodies.

[0046] In particular, the luminescent material is contained in a luminescent body. The luminescent body may be a layer, such as a self-supporting layer. The luminescent body may comprise 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 luminescent body may be essentially self-supporting. In certain embodiments, the luminescent material may be provided as a luminescent body, such as a luminescent single crystal, a luminescent glass, or a luminescent ceramic body. Such a body may be referred to as a "converter body" or a "luminescent body." In certain embodiments, the luminescent body may be a luminescent single crystal or a luminescent ceramic body. For example, in certain embodiments, a cerium-containing garnet luminescent material may be provided as a luminescent single crystal or a luminescent ceramic body. In other embodiments, the luminescent body may comprise a light-transmitting body in which the luminescent material is embedded. For example, the luminescent body may comprise a glass body with a luminescent material embedded in the glass body, or the glass itself may be luminescent, hi other embodiments, the luminescent body may comprise a polymer body with a luminescent material embedded in the polymer body.

[0047] A luminescent body may have any shape. However, in general, a luminescent body may have two essentially parallel faces that define the height of the luminescent body. Furthermore, a luminescent body may have an edge face that bridges the two essentially parallel faces. The edge face may be curved in one or two dimensions. The edge face may be planar. A luminescent body may have a rectangular or circular cross-section, although other cross-sections are also possible, such as a hexagonal or octagonal cross-section. Thus, a luminescent body may have a circular cross-section, an elliptical cross-section, a square cross-section, or a non-square rectangular cross-section. In some embodiments, a luminescent body may have an n-gonal 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. The two essentially parallel faces may be referred to as "main faces," particularly since they may provide the largest external area of ​​the luminescent body. Another cross section perpendicular to the aforementioned cross section may be rectangular in some embodiments. Thus, the luminescent body may have, for example, a cubic shape, a (non-cubic) rectangular parallelepiped shape, an n-gonal prism shape (pentagonal prism, hexagonal prism, etc.) where n is at least 5, and a cylindrical shape. However, other shapes may also be possible. In particular, the luminescent body may have a rectangular parallelepiped shape, a cylindrical shape, or an n-gonal prism shape where n is 6 or 8.

[0048] In certain embodiments, the luminescent body (or "body") has lateral dimensions width or length (W1 or L1) or diameter (D) and thickness or height (H1). In certain embodiments, (i) D≧H1, or (ii) W1≧H1 and / or L1≧H1. The luminescent body may be transparent or light-scattering. In certain embodiments, the luminescent body may comprise a ceramic luminescent material. In certain embodiments, L1≦10 mm, particularly L1≦5 mm, more particularly L1≦3 mm, most particularly L1≦2 mm. In certain embodiments, W1≦5 mm, more particularly W1≦3 mm, most particularly W1≦2 mm, and W1≦10 mm. In certain embodiments, H1≦5 mm, more particularly H1≦3 mm, most particularly H1≦2 mm, and H1≦10 mm. In certain embodiments, D≦10 mm, especially D≦5 mm, more especially D≦3 mm, most especially D≦2 mm. In certain embodiments, the body may have a thickness in the range of 50 μm to 1 mm, in some embodiments. Furthermore, the body may have a lateral dimension (width / diameter) in the range of 100 μm to 10 mm. In even further 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 twice as large as the height, such as at least five times larger. In certain embodiments, the luminescent body has a first length L1, a first height H1 and a first width W1, where H1≦0.5*L1 and H1≦0.5*W1. In certain embodiments, the luminescent body may be a (small) tile.

[0049] In some embodiments, the luminescent body may have a first surface, a second surface, and a side surface connecting the first surface and the second surface. The first surface and the second surface may be referred to as major surfaces. In the case of a cylinder, the side surface may be a single side surface. In the case of a rectangular parallelepiped, the side surface may have four facets. In the case of a hexagonal prism, the side surface may have six facets.

[0050] In certain embodiments, the luminescent body has an annular shape. Thus, in some embodiments, the luminescent body may have a hollow cylindrical shape. The hollow cylinder may have a height, which may be substantially constant across the ring and may be substantially independent of the radius. The annular shaped luminescent body may have an inner radius and an outer radius that define a width of the hollow cylindrical body. The width may be substantially the same across the entire luminescent body. The inner radius and outer radius may be greater than the height, for example, each may be at least twice as large as the height.

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

[0052] The term "luminescent material" particularly refers to a material capable of converting a first radiation, in particular one or more of UV radiation and blue radiation, into a second radiation. Generally, 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 be applied. Generally, the second radiation has a spectral power distribution at a wavelength greater than that of the first radiation, which is the case of so-called down-conversion. However, in certain embodiments, the second radiation has a spectral power distribution with an intensity at a wavelength less than that of the first radiation, which is the case of so-called up-conversion.

[0053] In certain embodiments, "luminescent material" may refer specifically to a material that can convert radiation, for example, into visible light and / or infrared light. For example, in certain embodiments, the luminescent material may be capable of converting one or more of UV radiation and blue radiation into visible light. The luminescent material may also, in certain embodiments, convert radiation into infrared radiation (IR). Thus, when excited with radiation, the luminescent material emits radiation. Generally, luminescent materials are downconverters, i.e., they convert radiation of a smaller wavelength into radiation of a larger wavelength (λ ex <λ em ), however, in certain embodiments, the luminescent material may comprise an upconverter luminescent material, i.e., a material in which radiation of a larger wavelength is converted into radiation having a smaller wavelength (λ ex >λ em ) is converted into radiation with the

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

[0055] The term "luminescent material" may also refer to a number of different luminescent materials. Examples of possible luminescent materials are provided below. Thus, the term "luminescent material" may, in certain embodiments, refer to a luminescent material composition. Instead of the term "luminescent material," the term "phosphor" may be applied. These terms are known to those skilled in the art.

[0056] In certain embodiments, the luminescent material is selected from garnets and nitrides, particularly doped with trivalent cerium or divalent europium, respectively. The term "nitride" may refer to oxynitrides or nitridosilicates, etc. Alternatively or additionally, the luminescent material may be selected from silicates, particularly doped with divalent europium.

[0057] In certain embodiments, the luminescent material is ABO 12 :Ce-type luminescent materials, where A in certain embodiments 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 B in certain embodiments comprises one or more of Al, Ga, In and Sc. In particular, A may comprise one or more of Y, Gd and Lu, in particular one or more of Y and Lu. In particular, B may comprise at least Al, such as one or more of Al and Ga, more particularly essentially only Al. Thus, particularly suitable luminescent materials are cerium-comprising garnet materials. Garnet embodiments are particularly those of A3B5O 12The garnet includes a garnet, where A includes at least yttrium or lutetium, and B includes at least aluminum. Such garnets may be doped with cerium (Ce), praseodymium (Pr), or a combination of cerium and praseodymium, and particularly doped with Ce. In particular, B may include aluminum (Al). In addition to aluminum, B may also partially include gallium (Ga) and / or scandium (Sc) and / or indium (In), particularly up to about 20% of B, more particularly up to about 10% of B (i.e., B ions consist essentially of 90 mol % or more of Al and 10 mol % or less of one or more of Ga, Sc, and In). B may particularly include up to about 10% of gallium. In another variation, B and O may be at least partially replaced by Si and N. The element A may be selected from the group consisting of yttrium (Y), gadolinium (Gd), terbium (Tb), and lutetium (Lu), among others. Furthermore, Gd and / or Tb may be present in an amount up to about 20% of A. In certain embodiments, the garnet luminescent material may be selected from the group consisting of (Y 1-x Lu x )3B5O 12 :Ce, where x is greater than or equal to 0 and less than or equal to 1. The term ":Ce" indicates that some of the metal ions in the luminescent material (i.e., in garnets, some of the "A" ions) are replaced with Ce. For example, (Y 1-x Lu x )3AlO 12 In the case of Ce, a portion of Y and / or Lu is replaced by Ce. This is known to those skilled in the art. Ce replaces A generally at a rate of 10% or less, and the Ce concentration is generally in the range of 0.1 to 4%, particularly 0.1 to 2% (relative to A). Assuming 1% Ce and 10% Y, the completely correct formula is (Y 0.1 Lu 0.89 Ce 0.01 )3AlO 12 The Ce in the garnet is substantially or exclusively in the trivalent state, as known to those skilled in the art.

[0058] In one embodiment, the luminescence material is (thus) A3B5O 12 and, in certain embodiments, up to 10% of the B-O may be replaced by Si-N.

[0059] In certain embodiments, the luminescence material is (Y x1 A' x2 Ce x3 )3(Al y1 B' y2 )5O 12 where x1 + x2 + x3 = 1, x3 > 0, 0 < x2 + x3 ≤ 0.2, y1 + y2 = 1, 0 ≤ y2 ≤ 0.2, A' includes one or more elements selected from the group consisting of lanthanides, and B' includes one or more elements selected from the group consisting of Ga, In, and Sc. In one embodiment, x3 is selected from the range of 0.001 to 0.1. In the present invention, in particular, x1 > 0.2, at least 0.8, x1 > 0. Garnets with Y can provide an appropriate spectral power distribution.

[0060] In certain embodiments, up to 10% of the B-O may 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), and in certain embodiments, B-O may refer to Al-O. As described above, in certain embodiments, x3 may be selected from the range of 0.001 to  0.04. In particular, such luminescence materials have an appropriate spectral distribution (see below), have relatively high efficiency, have relatively high thermal stability, and can enable a high CRI (optionally in combination with the light of other light sources as described herein). Thus, in certain embodiments, A may be selected from the group consisting of Lu and Gd. Alternatively or additionally, B may include Ga. Thus, in one embodiment, the luminescence material is (Y x1 (Lu,Gd) x2 Ce x3 )3(Al y1 Ga y2 )5O12 comprising, and Lu and / or Gd may be available. Even more particularly, x3 is selected from the range of 0.001 to 0.1, 0 < x2 + x3 ≦ 0.1, and 0 ≦ y2 ≦ 0.1. Further, in certain embodiments, up to 1% of B-O may be replaced by Si-N. Here, the percentage refers to moles (as is known in the art), for example, see also EP3149108. In even further particular embodiments, the luminescence material is (Y x1 Ce x3 )3Al5O 12 comprising, x1 + x3 = 1, 0 < x3 ≦ 0.2, and is 0.001 to 0.1, etc.

[0061] In certain embodiments, the light generating device may only comprise a luminescence material selected from the type of garnet containing cerium. In even further particular embodiments, the light generating device comprises a single type of luminescence material such as (Y x1 A' x2 Ce x3 )3(Al y1 B' y2 )5O<00​​​​​​​​​​​​​​

[0062] In certain embodiments, A may, among other things, include at least Y, and B may, among other things, include at least Al.

[0063] Alternatively or additionally, the luminescent material is A3Si6N 11 :Ce 3+ The present invention may include luminescent materials of the type A, where A includes one or more of Y, La, Gd, Tb, and Lu, such as one or more of La and Y in some embodiments.

[0064] In certain embodiments, the luminescent material may alternatively or additionally be MS:Eu 2+ and / or M2Si5N8:Eu 2+ and / or MAlSiN3:Eu 2+ and / or Ca2AlSi3O2N5:Eu 2+ etc., where M includes one or more of Ba, Sr, and Ca, particularly in certain embodiments, at least Sr. Thus, in certain 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, replacing one or more of the indicated divalent cations. Generally, Eu is not present in an amount greater than 10% of the cations, and the presence of Eu is particularly in the range of about 0.5-10%, more particularly in the range of about 0.5-5%, relative to the cation it replaces. The term ":Eu" indicates that a portion of the metal ions is Eu (in these examples, Eu 2+ For example, if we assume 2% Eu in CaAlSiN3:Eu, the correct formula is (Ca 0.98 EU 0.02)AlSiN3. Divalent europium generally replaces divalent cations, such as the divalent alkaline earth cations mentioned above, particularly Ca, Sr, or Ba. The material (Ba,Sr,Ca)S:Eu can also be denoted as MS:Eu, where 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 particularly calcium, in this compound. Here, Eu is introduced to replace at least a portion of M (i.e., one or more of Ba, Sr, and Ca). Furthermore, the material (Ba,Sr,Ca)2Si5N8:Eu can also be denoted as M2Si5N8:Eu, where 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 this compound. In a further particular embodiment, M consists of Sr and / or Ba (not taking into account the presence of Eu), Ba 1.5 Sr 0.5 Such materials include Si5N8:Eu (i.e., 75% Ba; 25% Sr), particularly consisting of 50-100%, more particularly 50-90% Ba, and 50-0%, particularly 50-10% Sr, where Eu is introduced to replace 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 represented as MAlSiN3:Eu, where M is one or more elements selected from the group consisting of barium (Ba), strontium (Sr), and calcium (Ca), and particularly M includes calcium or strontium, or calcium and strontium, more particularly calcium, in this compound. Where Eu is introduced to replace at least a portion of M (i.e., one or more of Ba, Sr, and Ca). The Eu in the above luminescent materials is substantially or exclusively in a divalent state, as known to those skilled in the art.

[0065] In certain embodiments, the red luminescent material may comprise 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, replacing one or more of the indicated divalent cations. Generally, Eu is not present in an amount greater than 10% of the cations, and the presence of Eu is particularly in the range of about 0.5-10%, more particularly in the range of about 0.5-5%, relative to the cations it replaces. The term ":Eu" indicates that a portion of the metal ions are Eu (in these examples, Eu 2+ For example, if we assume 2% Eu in CaAlSiN3:Eu, the correct formula is (Ca 0.98 EU 0.02 )AlSiN3. Divalent europium generally replaces a divalent cation, such as the divalent alkaline earth cations mentioned above, particularly Ca, Sr, or Ba.

[0066] The material (Ba,Sr,Ca)S:Eu can also be designated as MS:Eu, where M is one or more elements selected from the group consisting of barium (Ba), strontium (Sr) and calcium (Ca), and in particular M in this compound comprises calcium or strontium, or calcium and strontium, more particularly calcium, where Eu is introduced to replace at least a portion of M (i.e., one or more of Ba, Sr and Ca).

[0067] Furthermore, the material (Ba,Sr,Ca)2Si5N8:Eu can also be designated as M2Si5N8:Eu, where M is one or more elements selected from the group consisting of barium (Ba), strontium (Sr) and calcium (Ca), and in particular, M in this compound comprises Sr and / or Ba. In a further particular embodiment, M consists of Sr and / or Ba (not taking into account the presence of Eu), and Ba 1.5 Sr 0.5Particularly consisting of 50-100%, more particularly 50-90% Ba, and 50-0%, particularly 50-10% Sr, such as Si5N8:Eu (i.e., 75% Ba; 25% Sr), where Eu is introduced to replace at least a portion of M (i.e., one or more of Ba, Sr, and Ca).

[0068] Similarly, the material (Ba,Sr,Ca)AlSiN3:Eu can also be designated as MAlSiN3:Eu, where M is one or more elements selected from the group consisting of barium (Ba), strontium (Sr) and calcium (Ca), and in particular M in this compound comprises calcium or strontium, or calcium and strontium, more particularly calcium, where Eu is introduced to replace at least a portion of M (i.e., one or more of Ba, Sr and Ca).

[0069] The Eu in the above luminescent materials is substantially or exclusively in a divalent state, as known to those skilled in the art.

[0070] The blue luminescent material is YSO (Y2SiO5:Ce 3+ ), or similar compounds, or BAM (BaMgAl 10 O 17 :EU 2+ ), or a similar compound.

[0071] The term "luminescent material" as used herein particularly relates to inorganic luminescent materials.

[0072] Alternatively or additionally, other luminescent materials may be applied, for example quantum dots and / or organic dyes, optionally embedded in a transparent matrix, for example a polymer, such as PMMA or polysiloxane.

[0073] Quantum dots are small crystals of semiconductor materials, typically with a width or diameter of only a few nanometers. When excited by incident light, quantum dots emit light of a color determined by the size and material of the crystal. Therefore, by adjusting the size of the dot, light of a specific color can be generated. Most known quantum dots that emit in the visible range are based on cadmium selenide (CdSe) with a shell such as cadmium sulfide (CdS) and zinc sulfide (ZnS). Cadmium-free quantum dots such as indium phosphide (InP) and copper indium sulfide (CuInS2) and / or silver indium sulfide (AgInS2) can also be used. Quantum dots exhibit very narrow emission bands, thus allowing them to exhibit saturated colors. Furthermore, the emission color can be easily tuned by adjusting the size of the quantum dot. Any type of quantum dot known in the art may be used in the present invention. However, for reasons of safety and environmental concerns, it may be preferable to use cadmium-free quantum dots, or at least quantum dots with very low cadmium content.

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

[0075] Organic phosphors can also be used. Examples of suitable organic phosphor materials are organic luminescent materials based on perylene derivatives, such as the compounds sold by BASF under the name Lumogen®. Examples of suitable compounds include, but are not limited to, Lumogen® Red F305, Lumogen® Orange F240, Lumogen® Yellow F083, and Lumogen® F170.

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

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

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

[0079] Thus, the luminescent body may in particular be configured to be in a light-receiving relationship with the light-generating device, which may in particular be in a light-receiving relationship via an axicon-like optical element, as will be shown below.

[0080] The terms "light-receiving relationship" or "light receiving relationship" and similar terms may indicate that an item may receive light from a light source (such as a light-generating device or element or light-generating system) during operation of the light source. Thus, an item may be configured downstream of the light source. Optics may be configured between the light source and the item. The terms "upstream" and "downstream", such as in the context of light propagation, may particularly relate to the location of an item or feature with respect to the propagation of light from a light-generating element (here, particularly a light-generating device), such that with respect 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 (compared to the first position) is "upstream", and a third position in the light beam that is farther away from the light-generating element (compared to the first position) is "downstream". Instead of the term "light-generating element", the term "light-generating means" may be applied.

[0081] The optical relationship between the luminescent body and the axicon-like optical element is further described below, but first some aspects regarding the thermally conductive element are described.

[0082] The thermally conductive element may include, among other things, a thermally conductive material. The thermally conductive material may have, among other things, 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), particularly at least about 200 W / (m*K). In even more specific embodiments, the thermally conductive material may have, among other things, a thermal conductivity of at least about 10 W / (m*K). In certain embodiments, the thermally conductive material may include one or more of 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 thermally conductive material may include or consist of aluminum oxide. In some embodiments, the thermally conductive element may include one or more of a heat sink, a heat spreader, and a two-phase cooling device. In yet 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] An element may be considered to be in "thermal contact" with another element if the elements can exchange energy through a thermal process. Thus, the elements may be thermally coupled. In some embodiments, thermal contact can be achieved by physical contact. In some embodiments, thermal contact may be achieved through a thermally conductive material, such as a thermally conductive adhesive (or thermally conductive pressure-sensitive adhesive). Thermal contact may also be achieved between two elements when the two elements are disposed at a distance of about 10 μm or less relative to each other, although greater distances, 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 may be the distance between two respective surfaces of each element. The distance may be an average distance. For example, two elements may be in physical contact at one or more locations, such as multiple locations, but the elements may not be in physical contact at one or more, particularly multiple, other locations. For example, this may be the case if one or both elements have a rough surface. Thus, in some embodiments, the distance between two elements may be, on average, 10 μm or less (although larger average distances, such as up to 100 μm, are possible). In some embodiments, the two surfaces of two elements may be kept at a distance by one or more distance holders. When two elements are in thermal contact, they may be in physical contact or may be spaced apart from each other by a short distance, such as up to 10 μm, or up to 1 mm. When two elements are spaced apart from each other, an intermediate material may be disposed between them, although in other embodiments, the distance between the two elements may be filled with a gas, liquid, or vacuum. If an intermediate material is available, the greater the distance, the higher the thermal conductivity available for thermal contact between the two elements. However, the smaller the distance, the lower the thermal conductivity of the intermediate material may be (although a material with higher thermal conductivity may be used).

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

[0085] When an element is referred to herein as being transmissive, this may mean, in some embodiments, that the portion of radiation transmitted may be greater than the portion of radiation reflected or absorbed at one or more wavelengths. When an element is referred to herein as being reflective, this may mean, in some embodiments, that the portion of radiation reflected may be greater than the portion of radiation transmitted or absorbed at one or more wavelengths. As used herein, the term "transmissive" with respect to source light may refer to at least 50% of the incident source light passing through the material, particularly under normal illumination, such as at least 60%, particularly at least 70%, for example at least 80%, particularly at least 90%, for example at least 95%. Similarly, as used herein, the term "reflective" with respect to source light may refer to at least 50% of the incident source light being reflected, particularly under normal illumination, such as at least 60%, particularly at least 70%, for example at least 80%, particularly at least 90%, for example at least 95%. Here, percentages may refer to percentages based on watts.

[0086] As mentioned above, the system may further include an axicon-like optical element. The axicon-like optical element may include, among other things, a lens. In other words, the system may include a lens having an axicon-like shape. Axicon lenses are known in the art and can be defined, for example, as a special type of lens having a conical surface. Axicon lenses may be able to convert a laser beam into a ring-shaped distribution, among other things. (See, for example, http: / / wp.optics.arizona.edu / wp-content / uploads / 2016 / 03 / axicon_Proteep.pdf.) In this specification, the term axicon-like is used to indicate that small deviations from the axicon shape are possible. For example, the conical shape may, in some embodiments, be a bit rounded rather than essentially a pure cone (however, the radius of curvature of the surface of such a rounded conical shape should not be too small, e.g., larger than the (smallest) diameter of the axicon). Furthermore, in this specification, an axicon-like optical element may have a relatively large cylindrical part, which may be non-tapered or tapered (see also below).

[0087] In certain embodiments, the axicon-like optical element includes a first portion and a second portion. In particular, the axicon-like optical element may have an optical axis. The first portion may be configured rotationally symmetrically about the optical axis, and the second portion may be configured rotationally symmetrically about the optical axis. In particular, the axicon-like optical element is a monolithic body of optically transparent material, such as quartz, glass, sapphire, or a polymer material, essentially consisting of the first portion and the second portion. Furthermore, the axicon-like optical element may have an optical element length (L). In particular, this optical element length may be defined parallel to the optical axis. When the axicon-like optical element includes a polymer optically transparent material, such material may include, for example, one or more of polycarbonate (PC), silicone (polysiloxane), polystyrene, polymethyl methacrylate, etc. In particular, the axicon-like optical element may be a solid body essentially consisting of the optically transparent material.

[0088] In particular, the first portion may have a conical shape. The conical shape may, in particular, be a cone. Furthermore, the conical shape may have a conical angle selected from the range of approximately 90 to 178 degrees, such as selected from the range of approximately 105 to 125 degrees, more particularly at least approximately 100 degrees. Furthermore, the first portion may have a first length (L1). In particular, this first length may be defined parallel to the optical axis. Furthermore, the first portion may include a first end window. The term "end window" may refer to the fact that this end window may be configured at one end of the axicon-like optical element. Furthermore, this term may indicate that light may enter and / or exit particularly through that portion of the axicon-like 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 manner.

[0089] Furthermore, the second portion may have a cylindrical shape. Further, this portion may have a second length (L2). In particular, this second length may be defined parallel to the optical axis. Further, the second portion may include a second end window. In particular, this second portion may be essentially planar. The term "second end window" may refer to the fact that this end window can be configured at the other end of the axicon-like optical element. Further, this term may indicate that light can enter and / or escape particularly through this portion of the axicon-like optical element. In particular, the entire end surface of the cylinder may be the (second) end window. That said, this does not necessarily mean that the entire end window is used as such.

[0090] Regarding the axicon-like optical element, the first portion and the second portion, i.e., essentially the entire axicon-like 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 higher polygonal shapes are not excluded in this specification.

[0091] The optical element length (L) may be defined by the first end window, particularly the apex, and the second end window. Thus, in particular, L = L1 + L2. Further, in this specification, particularly L1 < L2. More particularly, in certain embodiments, 0.6 ≦ L2 / L < 1, more particularly 0.7 ≦ L2 / L < 1, for example 0.75 ≦ L2 / L ≦ 0.95. Further, in certain specific embodiments, 0.8 ≦ L2 / L < 1, more particularly 0.8 ≦ L2 / L ≦ 0.95. In certain embodiments, L2 / L may be selected from the range of 0.8 to 0.02. In particular, these shapes and dimensions may enable the dual function of the axicon-like optical element, as will be further described below.

[0092] In particular, an axicon-like optical element may be used to project light of a light-generating device onto a luminescent body, but may also be used to collect luminescent material light from the luminescent body and provide a beam of luminescent material light. Thus, in some embodiments, first device light enters through a first end window of the axicon-like optical element, but the luminescent material light may also exit the axicon-like optical element through this window. Similarly, first device light may propagate through the axicon-like optical element, optionally including (total) internal reflection, through a second end window of the axicon-like optical element, but the luminescent material light may also enter the axicon-like optical element through this second end window (and propagate through the axicon-like optical element, optionally including (total) internal reflection, back to the first end window of the axicon-like optical element and exit through this first end window).

[0093] Thus, in certain embodiments, the axicon-like optical element may be configured to (a) receive at least a portion of the first device light through a first portion (particularly a first end window) and provide an annular beam of the first device light to the luminescent body through a second portion (particularly a second end window), and (b) collect at least a portion of the luminescent material light through the second portion (particularly a second end window) and provide a beam of luminescent material light through the first portion (particularly a first end window).

[0094] As mentioned above, this can provide a relatively compact high-intensity light source. In particular, in this way, an annular phosphor can be provided in combination with an axicon lens to produce a laser-pumped high-intensity light source. As will be made clearer below, in certain embodiments, this can be a laser-pumped high-intensity white light source.

[0095] Further embodiments are described below.

[0096] As mentioned above, the cylinder portion may be non-tapered ("untapered") or tapered (see also below). In particular, in certain embodiments, the second portion may be tapered over at least part of the second length (L2) in the direction from the first portion to the second end window. This tapering may be useful, in particular, from the perspective of collimating the luminescent material light. Therefore, the minimum diameter of the axicon-like optical element may, in certain embodiments, be defined by the second end window. Thus, the minimum diameter of the second portion may, in certain embodiments, be the same as the maximum diameter of the first portion (non-tapered) or may be smaller (tapered). In particular, the ratio of the diameters is not less than 0.5. Therefore, in certain embodiments, the first end window may be smaller than the maximum first window radius (R w1 ), and the second end window may have a second window radius (R W2 ), and in some embodiments, R W2 / R W1 = 1 (non-tapered), or in other embodiments, R W2 / R W1 <1. In certain embodiments, 0.5≦R W2 / R W1 ≦0.98. In particular, these shapes and dimensions may enable the dual function of the axicon-like optical element, as further described below.

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

[0098] The light-generating system may be configured to generate system light. The system light may include at least a portion of the luminescent material light that escapes through the first end window. Such luminescent material light may 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 contribute to the system light and can provide white light with a desired correlated color temperature (CCT) and / or color rendering index (CRI). Several solutions appear possible, such as using a light source that bypasses the optical element and the luminescent material. However, the pump light itself may also be used as a component of the system light. This may be the case, in particular, when a portion of the first device light is reflected by the luminescent body and re-enters the axicon-like optical element through the second end window. In this case, the light exiting the first end window may include both the luminescent material light and a portion of the first device light. By selecting the radii of the axicon-like optical element and the luminescent body, the portion of the first device light that is reflected only by the thermally conductive element and may have essentially no interaction with the luminescent body may be controlled.

[0099] In some embodiments, about 2-35%, such as 2-30%, of the spectral power of the first device light escaping the second end window may be reflected by the thermally conductive material without interacting with the luminescent material or after transmitting through the luminescent material (i.e., propagating twice the optical path length), and reach the second end window again as unconverted reflected first device light. Here, percentage refers to the percentage of spectral power in watts. In some embodiments, up to about 70% of that (i.e., up to 70% of 35% (or 30%, respectively)), such as up to about 50%, may not interact with the luminescent material at all. Thus, in certain embodiments, the light-generation system may be configured such that a portion of the first device light escaping through the second end window is reflected off one or more of the thermally conductive element and the luminescent body, enters the axicon-like optical element through the second end window after reflection, and exits the axicon-like optical element through the first end window along with at least a portion of the luminescent material light, thereby providing a light beam comprising the first device light and the luminescent material light. Thus, the system light may comprise at least a portion of the first device light and at least a portion of the luminescent material light. In this manner, white system light may be provided by the light-generation system, optionally in combination with one or more additional light sources.

[0100] The light escaping the first end window and the first device light illuminating the first end window may have essentially parallel optical axes. Therefore, the optical element directing the first device light to the first portion and / or the optical element directing the luminescent material light away from the optical axis of the axicon-like optical element may, in some embodiments, be relatively small compared to the beam of luminescent material light escaping the first end window and / or may have a dichroic function. The former solution may be useful when reflected first device light also propagates along with the luminescent material light and should become part of the system light. The latter solution may be useful when such first device light is undesirable. A combination of solutions may also be applied. Such optics are also referred to herein as "first optics."

[0101] Thus, in some embodiments, the system may include optional first optics. In some embodiments, the first optics may be configured in the optical path of the first device light between the first light-generating device and the first end window. The first optics may be configured to reflect the first device light such that the first device light illuminates the first end window after reflection. In such embodiments, the first optics may include a reflector or a dichroic mirror, the latter being transmissive to the luminescent material light and reflective to the first device light. Although not further described herein, in alternative embodiments, the first optics may include a dichroic mirror that is reflective to the luminescent material light and transmissive to the first device light.

[0102] In one embodiment, the first end window has a maximum first window circular cross section (A w1) . Further, as noted above, the optional first optics may include a reflector. In certain embodiments, the reflector may include a dichroic mirror (reflective to the first device light and transmissive to the luminescent material light). In some embodiments, the reflector, such as a dichroic mirror, has a maximum first window circular cross section (A w1 ) is defined parallel to the optical cross section (A o1 ) In particular, A o1 / A w1 ≦0.5. In this way, the beam of luminescent material light is not too blocked by the reflector. In some embodiments, 0.01≦A o1 / A w1 ≦0.5. However, other values ​​may be possible. Values ​​greater than 0.5 may also be possible if the reflector is at a significant distance from the axicon-like optical element. However, this may be less desirable if a smaller system size is desired.

[0103] It appears to be useful if the first device light does not completely illuminate the first end window, but only a portion around the optical axis of the axicon-like optical element. In certain embodiments, the first light-generating device and optional first optics generate a pump beam circular cross section (A) at the first end window. p ) and in some embodiments, the first end window is configured to provide a beam of first device light having a maximum first window circular cross section (A w1 In particular, in one embodiment, A p / A w1 ≦0.8.

[0104] As mentioned above, the luminescent body may be configured to be in thermal contact with the thermally conductive body (see further below). In certain embodiments, the luminescent body may also be configured to be in thermal contact with the axicon-like optical element. Thus, basically, the following options are possible: (a) the luminescent body and the axicon-like optical element are not in optical contact and are not in thermal contact; (b) the luminescent body and the axicon-like optical element are in thermal contact but not optical contact; (c) the luminescent body and the axicon-like optical element are in thermal contact and optical contact but are not in physical contact; (d) the luminescent body and the axicon-like optical element are in thermal contact, optical contact and physical contact.

[0105] Thermal contact has been discussed above. When elements are in optical contact or optically coupled, they may be in physical contact with each other in some embodiments, or may be separated from each other by a (thin) layer of optical material, such as an optical adhesive, or other optically transparent interface material, e.g., having a thickness of less than about 1 mm, preferably less than 100 μm, in other embodiments. If an optically transparent interface material is not used, the (average) distance between two elements in optical contact may be on the order of a 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 wavelengths, it may be even smaller. Thus, if optical coupling is desired, an optically transparent interface material may be used. In yet other embodiments, if an optically transparent interface material is not used, the average distance between two elements in optical contact may be on the order of a relevant wavelength, such as the wavelength of the emission maximum. Thus, if optical contact is desired, there may be physical contact. However, even in such embodiments, there may be a non-zero average distance, but in that case, the average distance may be less than the wavelength of interest, such as about 700 nm, or (e.g., in terms of the use of reflected first device light) about 470 nm or less.

[0106] In certain embodiments, a first distance (d1) between the luminescent body and the second end window may be selected from the range of 0 to 0.1*L. In even more particular embodiments, the distance may be at least no greater than 100 μm. In even further embodiments, the distance may be no greater than about 0.7 μm, such as no greater than about 0.5 μm. Thus, in certain embodiments, the luminescent body and the second end window may be configured to be in optical contact (thus, the distance may be no greater than about 0.7 μm, such as no greater than about 0.5 μm).

[0107] For efficiency reasons, it appears useful if the end window has a diameter (or radius) that is (slightly) larger than the maximum diameter (or radius) of the luminescent body. In particular, the luminescent body is positioned such that the diameter (or radius) of the end window is (slightly) larger than the maximum diameter (or radius) of the luminescent body outer radius (r lo ) and the inner radius of the luminescent body (r li ). In particular, the second end window has a second window radius (R W2 As will be apparent to those skilled in the art, in particular, R lo >r li Furthermore, in some embodiments, 0.7≦r lo / R W2 ≦1.05, more particularly, 0.80≦r lo / R W2 ≦1. Furthermore, in some embodiments, 0.85≦r lo / R W2 <1, more particularly, 0.85≦r lo / R W2 <1, e.g., 0.85≦r lo / R W2 ≦0.99.

[0108] In particular, the luminescent body may have a first surface facing the second end window, a side surface, and a bottom surface configured furthest from the second end window. In some embodiments, at least the bottom surface may be in at least partial thermal contact with the thermally conductive element. More particularly, in some embodiments, the side surface and the bottom surface may be configured to be in thermal contact with the thermally conductive element. For example, this may be the case when the thermally conductive element includes a slit in which the luminescent body may be at least partially hosted. Thus, in some embodiments, the thermally conductive element may include an annular slit that hosts at least a portion of the luminescent body, and in particular, the side surface and the bottom surface may be configured to be in thermal contact with the thermally conductive element. One or both side surfaces may be in thermal contact over a portion of their height, or over the entire height.

[0109] Thus, in certain embodiments, the thermally conductive body may include an annular slit having a shape (and dimensions) corresponding to the annular luminescent body.

[0110] In certain embodiments, the luminescent material is ABO 12 :Ce-type luminescent materials, where A may include one or more of Y, La, Gd, Tb and Lu, and B may include one or more of Al, Ga, In and Sc (see also further above). In particular, such luminescent materials may be stable at high pumping powers. As mentioned above, the term "luminescent material" may also refer in some embodiments to a combination of two or more different luminescent materials.

[0111] In certain embodiments, the luminescent body may comprise a ceramic body, such as ABO. 12 Ceramic bodies, such as those containing :Ce-type luminescent materials, can be particularly useful in terms of thermal management due to their relatively high thermal conductivity.

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

[0113] As mentioned above, the system light may include luminescent material light, optionally including first device light. It may be desirable for the optical properties of such light to be further adapted and / or more controllable in terms of CRI, CCT, and color point. To that end, one or more further light-generating devices (denoted as "second light-generating device") may be applied.

[0114] Such a second light-generating device may not be configured to provide second light that must propagate through an axicon-like optical element, nor may it be configured to interact (including be transmitted and / or reflected) by the luminescent body, although neither of these options are excluded herein.

[0115] Furthermore, one or more second light-generating devices may be configured to provide second device light having essentially the same spectral power distribution as the first device light, but such one or more second light-generating devices may be configured to bypass the luminescent body with the second device light. 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 (see further below).

[0116] Alternatively or additionally, one or more (other) second light-generating devices may be configured to provide second device light having a spectral power distribution substantially different from that of the first device light. Such one or more (other) second light-generating devices may also be configured to bypass the luminescent body with their second device light. 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 (see further below).

[0117] Either way, the CCT, CRI, and color point can be further adjusted and / or controlled.

[0118] Device light from one or more second light-generating devices may be combined into the luminescent material light (and optionally the (unconverted) first device light) using a beam combiner. Thus, in certain embodiments, the light-generation system may further include a beam combiner and a second light-generating device. The second light-generating device may be configured to generate second device light. The beam combiner may be configured to combine the first luminescent material light downstream of the first end window, the optional first device light, and the second device light. In certain embodiments, the second light-generating device may be configured to generate 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 certain embodiments, the second device light may have an intensity within the orange-red wavelength range (i.e., a wavelength range of 590-750 nm).

[0119] In certain embodiments, in an operating mode of the light-generating system, the system light may be white light, which may be based on the luminescent material light and one or more of the first device light and the second device light.

[0120] The term "white light" and similar terms used herein are known to those skilled in the art. White light may refer to light having a correlated color temperature (CCT), particularly between about 2000K and 20000K, particularly between about 1800K and 20000K, such as 2700K to 20000K, and for general illumination, particularly within the range of about 2000K to 7000K, such as within the range of 2700K to 6500K. In some embodiments, for example, for backlighting purposes or other purposes, the correlated color temperature (CCT) may be particularly within the range of about 7000K to 20000K. Furthermore, in some embodiments, the correlated color temperature (CCT) is particularly within about 15 SDCM (standard deviation of color matching) of the black body locus (BBL), particularly within about 10 SDCM of the BBL, and even more particularly within about 5 SDCM of the BBL.

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

[0122] As mentioned above, in certain embodiments, the system may further include (or be operatively 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 "controlling" and similar terms particularly refer to at least determining the behavior of an element or supervising the execution of an element. Thus, in this specification, "controlling" and similar terms may refer to imposing a behavior on an element (determining the behavior of an element or supervising the execution of an element), such as measuring, indicating, activating, opening, shifting, changing temperature, etc. Additionally, the term "controlling" and similar terms may also include monitoring. Thus, the term "controlling" and similar terms may include imposing a behavior on an element, as well as imposing a behavior on an element and monitoring an element. Control of an element can be performed using a control system, which may also be referred to as a "controller." Thus, the control system and the element can be functionally coupled, at least temporarily or permanently. An element may include a control system, although in some embodiments, the control system and the element may not be physically coupled. Control can be performed via wired and / or wireless control. The term "control system" may also refer to a number of different control systems, particularly those that are functionally coupled, where, for example, one control system may be a master control system and one or more other control systems may be slave control systems. A control system may include a user interface or be functionally coupled to a user interface.

[0124] The control system may also be configured to receive and execute commands from a remote control. In some embodiments, the control system may be controlled via an app on a device, such as a portable device, such as a smartphone or iPhone, tablet, etc. Thus, the device may be (temporarily) functionally coupled to the lighting system, although not necessarily coupled to the lighting system.

[0125] Thus, in some embodiments, the control system may be (also) configured to be controlled by an app on a remote device. In such embodiments, the control system of the lighting system may be a slave control system or may be controlled in slave mode. For example, the lighting systems may be identifiable by a code, in particular a unique code for each lighting system. The control system of the lighting system may be configured to be controlled by an external control system that accesses the lighting system based on knowledge entered by a user interface comprising an optical sensor of the (unique) code (e.g., a QR code reader). The lighting system may also include 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 apparatus, or device may perform an action in a "mode" or "operation mode" or "mode of operation" or "operational mode". The term "operation mode" may also be indicated as a "controlling mode". Similarly, in a method, an action, or a phase, or a step may be performed in a "mode" or "operation mode" or "mode of operation" or "operational mode". This does not exclude that the system, or apparatus, or device may be adapted to provide another control mode or multiple other control modes. Likewise, this does not exclude that one or more other modes may be performed before and / or after performing a mode.

[0127] However, in some embodiments, a control system may be available that is adapted to provide at least the control mode. If other modes are available, the selection of such modes may be performed particularly via a user interface, although other options are possible, such as implementing the mode depending on a sensor signal or a (time) scheme. Operational mode may also refer in some embodiments to a system, apparatus, or device that can only operate in a single operational mode (i.e., "on" and without further adjustability).

[0128] Thus, in some embodiments, the control system may depend on one or more of a user interface input signal, a sensor signal (of a sensor), and a timer, where the term "timer" may refer to a clock and / or a predetermined timing scheme.

[0129] The light-generating system may be part of or used in, for example, an office lighting system, a household application system, a store lighting system, a home lighting system, an accent lighting system, a spot lighting system, a theatrical lighting system, a fiber optic application system, a projection system, a self-lit 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, an automotive application, an (outdoor) road lighting system, an urban lighting system, a greenhouse lighting system, horticultural lighting, digital projection, or LCD backlighting, etc. The light-generating system (or luminaire) may be part of or used in, for example, an optical communication system or a disinfection system.

[0130] In yet a further aspect, the present invention also provides a lamp or luminaire comprising a light-generating system as defined herein. The luminaire may further comprise a housing, optical elements, louvers, etc. The lamp or luminaire may further comprise a housing enclosing the light-generating system. The lamp or luminaire may have a light window or housing opening in the housing, and the system light may escape from the housing through the light window or housing opening. In yet a further 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 a projection screen. The projection device may comprise one or more light-generating systems as described herein. Thus, in an aspect, the present invention also provides a light-generating device selected from the group of a lamp, a luminaire, a projector device, a disinfection device, a photochemical reactor, and an optical wireless communication device, the light-generating device comprising a light-generating system as defined herein. The light-generating device may include a housing configured to accommodate or a carrier configured to support one or more elements of the light-generating system. For example, in some embodiments, the light-generating device may include a housing configured to accommodate or a carrier configured to support one or more of the one or more first light-generating devices, the axicon-like optical element, the thermally conductive element, and optionally one or more second light-generating devices. [Brief explanation of the drawings]

[0131] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which the drawings are not necessarily to scale. [Figure 1]1a-1d illustrate some embodiments and aspects in a schematic manner. [Figure 2] FIG. 2 illustrates a schematic diagram of some application embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0132] 1a-1d show a schematic representation of an embodiment of a light-generation system 1000 and related aspects of the light-generation system 1000, including a first light-generation device 110, a luminescent body 1200, a thermally conductive element 500, and an axicon-like optical element 400.

[0133] The first light-generating device 110 may be configured to generate first device light 111. The first light-generating device 110 may include one or more of a superluminescent diode and a solid-state laser.

[0134] The luminescent body 1200 may comprise a luminescent material 200 configured to convert at least a portion of the first device light 111 into luminescent material light 201. The luminescent body 1200 may have an annular shape (see also FIG. 1b).

[0135] Thermally conductive element 500 may optionally include an annular slit 510 that receives at least a portion of luminescent body 1200. Thermally conductive element 500 may be reflective to one or more of first device light 111 and luminescent material light 201.

[0136] The axicon-like optical element 400 may include a first portion 410 and a second portion 420 and may have an optical element length L. The first portion 410 may have a conical shape, a first length L1, and may include a first end window 411. The second portion 420 may have a cylindrical shape, a second length L2, and may include a second end window 422. In some embodiments, 0.7≦L2 / L<1.

[0137] The axicon-like optical element 400 may be configured to (a) receive at least a portion of the first device light 111 through the first window portion 410 and provide an annular beam of the first device light 111 to the luminescent body 1200 through the second window portion 420, and (b) collect at least a portion of the luminescent material light 201 through the second window portion 420 and provide a beam of luminescent material light 201 through the first window portion 410.

[0138] In some embodiments, the second portion 420 may taper over at least a portion of the second length L2 in a direction from the first portion 410 to the second end window 422.

[0139] The first end window 411 has a maximum first window radius (R w1 ), and the second end window 422 may have a second window radius (R W2 In some embodiments, 0.5≦R W2 / R W1 ≦0.98. Furthermore, in some embodiments, 0.8≦L2 / L<1.

[0140] The light generation system 1000 may be configured such that a portion of the first device light 111 escaping through the second end window 422 is reflected by one or more of the thermally conductive element 500 and the luminescent body 1200, enters the axicon-like optical element 400 through the second end window 422 after reflection, and, together with at least a portion of the luminescent material light 202, escapes the axicon-like optical element 400 through the first end window 411 to provide a light beam comprising the first device light 111 and the luminescent material light 201.

[0141] The first end window 411 has a maximum first window circular cross section A w1 The optional first optics 610 may include a reflector 611, such as a dichroic mirror 612 in certain embodiments. The optional first optics may reflect the pump beam circular cross section A p and the maximum first window circular cross section A w1The optical cross section A is defined parallel to o1 In some embodiments, A o1 / A w1 ≦0.5.

[0142] In an embodiment, the first light-generating device 110 and optional first optics 610 provide a pump beam with a circular cross section A at the first end window 411. p Further, the first end window 411 may be configured to provide a beam of first device light 111 having a maximum first window circular cross section A w1 In some embodiments, A p / A w1 ≦0.8.

[0143] In certain embodiments, the first distance d1 between the luminescent body 1200 and the second end window 422 may be selected from the range of 0 to 0.1*L. In Figure 1a, d1 is essentially zero, while Figure 1c schematically depicts an embodiment in which d1 is non-zero.

[0144] In certain embodiments, for example, with reference to Figures 1a and 1c, the luminescent body 1200 and the second end window 422 may be configured to be in optical contact.

[0145] 1a-1d, the luminescent body 1200 has an outer luminescent body radius r lo and the inner radius of the luminescent body r li The second end window 422 may have a second window radius R W2 In particular, r lo >r li Furthermore, in certain embodiments, 0.85≦r Lo / R W2 <1.

[0146] The luminescent body 1200 may have a first face 1201 facing the second end window 422, a side face 1202, and a bottom face 1203 configured furthest from the second end window 422. In certain embodiments, the bottom face 1203, and optionally the side face 1202 as well, may be configured to be in thermal contact with the thermally conductive element 500.

[0147] In some embodiments, the thermally conductive element 500 may be selected from the group including a heat sink, a heat spreader, and a two-phase cooling device.

[0148] In one embodiment, luminescent material 200 is ABO 12 :Ce type luminescent material, A may include one or more of Y, La, Gd, Tb, and Lu, and B may include one or more of Al, Ga, In, and Sc. In certain embodiments, luminescent body 1200 may include a ceramic body.

[0149] In some embodiments, the first light-generating device 110 may include a blue (laser) light emitting diode laser.

[0150] In some embodiments, the light-generation system 1000 may further include a beam combiner 620 and a second light-generation device 120. The second light-generation device 120 may be configured to generate a second device light 121 having a second spectral power distribution that is different from the first spectral power distribution of the first device light 111, or the spectral power distributions may be essentially the same. In certain embodiments, the second device light 121 has an intensity in the orange-to-red wavelength range that is different from the first spectral power distribution of the first device light 111. The beam combiner 620 may be configured to combine the first luminescent material light 201 downstream of the first end window 411 with the second device light 121 (and, optionally, with the first device light 111). The light-generating system 1000 may be configured to generate a system light 1001 that includes at least a portion of the combined first luminescent material light 201 , the first device light 111 , and the second device light 121 .

[0151] In an operational mode of the light-producing system 1000, the system light 1001 may be white light.

[0152] FIG. 2 schematically illustrates an embodiment of a lighting fixture 2 including a light-generating system 1000 as described above. Reference number 301 indicates a user interface that may be included in the light-generating system 1000 or that may be functionally coupled to a control system 300 that is functionally coupled to the light-generating system 1000. FIG. 2 also schematically illustrates an embodiment of a lamp 1 including the light-generating system 1000. Reference number 3 indicates a projector device or projector system that may be used to project an image onto a wall or the like, and that may also include the light-generating system 1000. Accordingly, FIG. 2 schematically illustrates an embodiment of an illumination device 1200 selected from the group of a lamp 1, a lighting fixture 2, a projector device 3, a disinfection device, a photochemical reactor, and an optical wireless communication device, the illumination device 1200 including the light-generating system 1000 as described herein. In an embodiment, such an illumination device may be a lamp 1, a lighting fixture 2, a projector device 3, a disinfection device, or an optical wireless communication device. Illumination device light escaping illumination device 1200 is shown at 1201. Illumination device light 1201 may consist essentially of, and thus in certain embodiments may be, system light 1001. Reference numeral 1300 refers to a space, such as a room. Reference numeral 1305 refers to the floor, reference numeral 1310 refers to the ceiling, and reference numeral 1307 refers to the walls.

[0153] In some embodiments, the phosphor disk is attached to a reflective heat sink, allowing heat to be removed through the back and sides of the phosphor tile. When such a disk is illuminated by a pump laser, a hot spot occurs in the center of the disk, limiting the achievable power density.

[0154] In particular, it is proposed herein to use an annular-shaped phosphor to increase the contact area with the heat sink, thus preventing overheating of the phosphor by cooling it from the sides as well as the top and bottom. The annular phosphor can be illuminated with an annular pump beam created using an axicon optical element. The same axicon is then used to collect the emitted light.

[0155] In the simulations performed, there is a small air gap between the axicon and the phosphor, however, it is also possible to place the axicon directly on top of the phosphor surface for additional cooling and reduced reflections.

[0156] The axicon may consist of a tapered cylindrical rod with a conical top surface. A specific value of the cone's apex angle allows a hollow, ring-shaped pump beam to effectively illuminate the annular phosphor. It is proposed herein to use the same axicon optical element to collect the converted light and 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.

[0157] In particular, the blue pump light is coupled into the axicon using a small dichroic mirror, although a small reflector may also be applied. Part of the blue pump light can be reflected from the phosphor and from parts of the heat sink that may not be covered by the phosphor. The blue reflection of the heat sink can be designed so that the total output is well white balanced.

[0158] Referring to FIG. 1d, it can be seen that light can be efficiently directed into the phosphor.

[0159] Based on modeling, it can be concluded that an axicon projecting an annular blue light pattern onto a phosphor will collect the light emitted by the axicon phosphor and create a circular beam.

[0160] Table 1 below presents some results for different Axicon and Phosphor combinations. It can be seen that as the phosphor area increases, so does the FWHM: TIFF0007746632000002.tif61166

[0161] The term "plurality" refers to two or more.

[0162] The terms "substantially" or "essentially" used herein will be understood by those skilled in the art. The terms "substantially" or "essentially" may also include embodiments with "entirely," "completely," "all," etc. Thus, in embodiments, the adjective "substantially" or "essentially" may be omitted. Where applicable, the terms "substantially" or "essentially" may also relate to 90% or more, including 100%, such as 95% or more, particularly 99% or more, and more particularly 99.5% or more.

[0163] The term "comprise" also includes embodiments in which the term "comprise" means "consists of."

[0164] The term "and / or" specifically refers 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 refer to one or more of items 1 and 2. The term "comprising" may, in one embodiment, refer to "consisting of," but in another embodiment may also refer to "including at least the defined species, and optionally one or more other species."

[0165] Furthermore, terms such as first, second, third, etc. in the specification and claims are used to distinguish between similar elements and not necessarily to describe a sequential or chronological order. The terms so used are interchangeable under appropriate circumstances, with the understanding that the embodiments of the invention described herein are capable of operating in other sequences than those described or illustrated herein.

[0166] Devices, apparatus, or systems are described herein, inter alia, in operation. As will be apparent to those skilled in the art, the present invention is not limited to methods of operation or devices, apparatus, or systems in operation.

[0167] It should be noted that the above-described embodiments are illustrative rather than limiting of the present invention, and that those skilled in the art can design many alternative embodiments without departing from the scope of the appended claims.

[0168] In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

[0169] Use of the verb "to comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. Unless the context clearly indicates otherwise, throughout the specification and claims, the words "comprise", "comprising", and the like should be interpreted in their inclusive sense, i.e., "including, but not limited to", rather than their exclusive or exhaustive sense.

[0170] The singular reference of an element does not exclude the presence of a plurality of such elements.

[0171] The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In a device, apparatus, or system claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain means are recited in mutually different dependent claims does not indicate that a combination of these means cannot be used to advantage. In yet another aspect, the invention thus provides a software product which, when run on a computer, is capable of implementing (one or more embodiments of) the method as described herein.

[0172] The present invention also provides a control system that can control a device, apparatus, or system or that can perform the methods or processes described herein. Still further, the present invention also provides a computer program product that, when executed on a computer operatively coupled to or included in a device, apparatus, or system, controls one or more controllable elements of such device, apparatus, or system.

[0173] The present invention further applies to a device, apparatus or system comprising one or more of the features described in the present specification and / or shown in the accompanying drawings. The present invention further relates to a method or process comprising one or more of the features described in the present specification and / or shown in the accompanying drawings.

[0174] The various aspects discussed in this patent may be combined to provide additional advantages. Moreover, those skilled in the art will appreciate that embodiments may be combined, and that three or more embodiments may be combined. Furthermore, some of the features may form the basis for one or more divisional applications.

Claims

1. 1. A light-generating system comprising a first light-generating device, a luminescent body, a thermally conductive element, and an axicon-like optical element, the first light-generating device is configured to generate first device light, the first light-generating device including one or more of a superluminescent diode and a solid-state laser; the luminescent body includes a luminescent material configured to convert at least a portion of the first device light to luminescent material light, the luminescent body having an annular shape; the thermally conductive element is (a) configured to be in thermal contact with at least a portion of the luminescent body; and (b) is reflective to one or more of the first device light and the luminescent material light; the axicon-like optical element includes a first portion and a second portion and has an optical element length (L), the first portion having a conical shape, a first length (L1), and including a first end window, and the second portion having a cylindrical shape, a second length (L2), and including a second end window, wherein 0.7≦L2 / L<1; the axicon-like optical element (a) receives at least a portion of the first device light through the first portion and provides an annular beam of first device light to the luminescent body through the second portion, and (b) collects at least a portion of the luminescent material light through the second portion and provides a beam of luminescent material light through the first portion. The light generating system is configured to:

2. 10. The light production system of claim 1, wherein the second portion tapers over at least a portion of the second length in a direction from the first portion to the second end window.

3. The first end window has a maximum first window radius (R ｗ１ ), and the second end window has a second window radius (R Ｗ２ ) and 0.5≦R Ｗ２ / R Ｗ１ 3. The light-generating system of claim 2, wherein L / L is ≦0.98 and 0.8≦L / L<1.

4. 3. The light-generation system of claim 1, configured such that a portion of the first device light escaping through the second end window is reflected off one or more of the thermally conductive element and the luminescent body, enters the axicon-like optical element through the second end window after reflection, and escapes the axicon-like optical element through the first end window together with at least a portion of the luminescent material light, to provide a light beam comprising first device light and luminescent material light.

5. The light production system further includes first optics, the first end window having a maximum first window circular cross section (A ｗ１ ), and the first optics has the largest first window circular cross section (A ｗ１ ) is defined parallel to the optical cross section (A ｏ１ ), and A ｏ１ / A ｗ１ 3. The light-generating system of claim 1 or 2, wherein ≦0.

5.

6. The first light-generating device and the first optics are configured to generate a pump beam circular cross section (A ｐ ) and the first end window is configured to provide a beam of first device light having a maximum first window circular cross section (A ｗ１ ) and A ｐ / A ｗ１ 6. The light-generating system of claim 5, wherein ≦0.

8.

7. 3. The light generation system of claim 1, wherein a first distance between the luminescent body and the second end window is selected from the range of 0 to 0.1*L.

8. The luminescent body and the second end window are configured to be in optical contact, and the luminescent body has a luminescent body outer radius (R Ｌｏ ) and the luminescent body inner radius (R Ｌｉ ), and the second end window has a second window radius (R Ｗ２ ) and R Ｌｏ >R Ｌｉ and 0.85≦R Ｌｏ / R Ｗ２ 3. The light-generating system of claim 1 or 2, wherein <1.

9. 3. The light generation system of claim 1, wherein the thermally conductive element includes an annular slit that receives at least a portion of the luminescent body, the luminescent body having a first surface facing the second end window, a side surface, and a bottom surface configured furthest from the second end window, the side surface and the bottom surface configured to be in thermal contact with the thermally conductive element.

10. The light generation system of claim 1 or 2, wherein the thermally conductive element is selected from the group comprising a heat sink, a heat spreader, and a two-phase cooling device.

11. The luminescent material is A ３ B ５ O １２ 3. The light generating system of claim 1 or 2, comprising a luminescent material of the Ce type, wherein A comprises one or more of Y, La, Gd, Tb and Lu, and B comprises one or more of Al, Ga, In and Sc.

12. The light-generating system of claim 1 or 2, wherein the luminescent body comprises a ceramic body.

13. 3. The light-generating system of claim 1 or 2, wherein the first light-generating device comprises a blue light-emitting diode laser.

14. 3. The light-generation system of claim 1, further comprising: a beam combiner; and a second light-generation device configured to generate second device light having a second spectral power distribution different from the first spectral power distribution of the first device light, the second device light having an intensity in an orange to red wavelength range; the beam combiner configured to combine the first luminescent material light downstream of the first end window with the second device light; and the light-generation system configured to generate system light including at least a portion of the combined first luminescent material light, first device light, and second device light, wherein in an operation mode of the light-generation system, the system light is white light.

15. 10. An illumination device selected from the group of a lamp, a luminaire, a projector device, a disinfection device, a photochemical reactor, and an optical wireless communication device, comprising a light-generating system according to claim 1 or 2.

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