Laser-phosphor white light source comprising diffused blue laser light, green filtered LUAG light, red filtered YAG light, and a method of CTT control

Abstract

The invention provides a light generating system (1000) comprising light generating devices (100), a first luminescent material (210), a second luminescent material (220), dichroic mirrors (400), a beam combiner (500), and a diffuser (710), wherein: (A) the diffuser (710) is configured in a light-receiving relationship with a first light generating device (110) and is configured to diffuse first device light (111) received by the diffuser (710) into diffused first device light (711); (C) the first luminescent material (210) is configured in a light-receiving relationship with a second light generating device (120) and is configured to convert second device light (121) into first luminescent material light (211); (D) the second luminescent material (220) is configured in a light-receiving relationship with a third light generating device (130) and is configured to convert the third device light (131) into second luminescent material light (221); (E) the dichroic mirrors (400) comprise (a) a first dichroic beam splitter (410), having a first cut-off wavelength (λC1), configured in a light-receiving relationship with the first luminescent material (210) and is configured (i) to transmit or reflect a first part of the first luminescent material light (211a) having a wavelength selected from the range of <λC1 and (ii) to reflect or transmit a second part of the first luminescent material light (211b) having a wavelength selected from the range of >λC1; and (b) a second dichroic beam splitter (420), having a second cut-off wavelength (λC2); wherein λC1≠λC2, configured in a light-receiving relationship with the second luminescent material (220) and is configured (i) to transmit or reflect a first part of the second luminescent material light (221a) having a wavelength selected from the range of <λC2 and (ii) to reflect or transmit a second part of the second luminescent material light (221b) having a wavelength selected from the range of >λC2; wherein the second dichroic beam splitter (420) is configured to provide the first part of the second luminescent material light (221b) back to the second luminescent material (220); (F) the beam combiner (500) is configured to combine the diffused first device light (711), the first part of the first luminescent material light (211a), and the second part of the second luminescent material light (221a) received by the beam combiner (500) into a beam of system light (1001), wherein the system light (1001) is white light having a correlated color temperature in a range from 2000-9000 K and a CRI of at least 70.

Description

[0001] LASER-PHO SPHOR WHITE LIGHT SOURCE COMPRISING DIFFUSED BLUE LASER

[0002] LIGHT, GREEN FILTERED LUAG LIGHT, RED FILTERED YAG LIGHT, AND A

[0003] METHOD OF CTT CONTROL

[0004] FIELD OF THE INVENTION

[0005] The invention relates to a light generating system. The invention further relates to a lighting device comprising the light generating system.

[0006] BACKGROUND OF THE INVENTION

[0007] Laser-phosphor white light sources are known in the art. For instance, US2019235369A1 describes a system for solid state illumination where light from at least two assisting light sources is added to a phosphor converted light beam. Different amounts of the assisting light can be added at different points in time. The overall brightness and / or the color performance of the system can be enhanced.

[0008] SUMMARY OF THE INVENTION

[0009] High brightness light sources can be used in various applications including spots, stage-lighting, headlamps, home and office lighting, and automotive lighting. For this purpose, laser-phosphor technology can be used, wherein a laser provides laser light and a remote phosphor converts laser light into converted light. A relatively straightforward way to produce white light using lasers is to use (blue) laser light in combination with a (yellow) phosphor to generate phosphor converted light. Laser-phosphor systems may allow generation of high brightness light. In general, the maximum brightness for a laser-phosphor light engine is limited by the components used, the engine volume is large due to the many components, and the system costs are high due to the many dedicated components. Especially, the performance of this technology may be limited as quenching of the phosphor may be required for obtaining high quality light and providing control of the correlated color temperature (CCT) . Hence, it may be desired to improve the performance of laser-phosphor lighting fixtures.

[0010] Hence, it is an aspect of the invention to provide an alternative light generating system, which preferably further at least partly obviates one or more of above-described drawbacks. The present invention may have as object to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.

[0011] According to a first aspect, the invention provides a light generating system configured to provide system light. In embodiments, the light generating system may comprise light generating devices, a first luminescent material, a second luminescent material, dichroic mirrors, a beam combiner, and a diffuser. Each of the light generating devices may, in embodiments, comprise a solid-state light source. Especially, the solid-state light source may be selected from the group comprising a light-emitting diode (such as a e.g. multi -junction stacked LED), a laser diode, and a superluminescent diode. The light generating devices may, in embodiments, comprise a first light generating device configured to generate first device light. Additionally, in embodiments, the light generating devices may comprise a second light generating device configured to generate second device light. Additionally, in embodiments, the light generating devices may comprise a third light generating device configured to generate third device light. Especially, in embodiments, the first device light, the second device light, and the third device light may each have a centroid wavelength individually selected from the wavelength range of 440-490 nm. Further, in embodiments, the diffuser may be configured in a light-receiving relationship with the first light generating device. The diffuser may especially be configured to diffuse (or scatter) (at least part of) the first device light received by the diffuser into diffused first device light. Similarly, in embodiments, the first luminescent material may be configured in a lightreceiving relationship with the second light generating device. The first luminescent material may especially be configured to convert (at least part of) the second device light received by the first luminescent material into first luminescent material light. In embodiments, the first luminescent material light may have a first peak emission wavelength ( i) selected from the wavelength range of 500-540 nm. Analogously, in embodiments, the second luminescent material may be configured in a light-receiving relationship with the third light generating device. The second luminescent material may especially be configured to convert (at least part of) the third device light received by the second luminescent material into second luminescent material light. In embodiments, the second luminescent material light may have a second peak emission wavelength ( 2) selected from the wavelength range of 540-590 nm. Further, in embodiments, the dichroic mirrors may comprise a first dichroic beam splitter. In embodiments, the first dichroic beam splitter may have a first cut-off wavelength ( ci). Additionally, in embodiments, the dichroic mirrors may comprise a second dichroic beam splitter. In embodiments, the second dichroic beam splitter may have a second cut-off wavelength ( ci). Especially, in embodiments, the first cut-off wavelength ( ci) and the second cut-off wavelength ( ci) may be different, i.e., ci ci. Furthermore, in embodiments, the first dichroic beam splitter may be configured in a light-receiving relationship with the first luminescent material. In embodiments, the first dichroic beam splitter may be configured (a) to transmit (at least part of) a first part of the first luminescent material light having a wavelength selected from the range of <Xci and (b) to reflect (at least part of) a second part of first luminescent material light having a wavelength selected from the range of > ci. Additionally or alternatively, in embodiments, the first dichroic beam splitter may be configured (a) to reflect (at least part of) a first part of the first luminescent material light having a wavelength selected from the range of <Xci and (b) to transmit (at least part of) a second part of first luminescent material light having a wavelength selected from the range of > ci. Analogously, in embodiments, the second dichroic beam splitter may be configured in a light-receiving relationship with the second luminescent material. In embodiments, the second dichroic beam splitter may be configured (a) to transmit (at least part of) a first part of the second luminescent material light having a wavelength selected from the range of <Xc2 and (b) to reflect (at least part of) a second part of second luminescent material light having a wavelength selected from the range of >Xc2. Additionally or alternatively, in embodiments, the second dichroic beam splitter may be configured (a) to reflect (at least part of) a first part of the second luminescent material light having a wavelength selected from the range of <><2 and (b) to transmit (at least part of) a second part of second luminescent material light having a wavelength selected from the range of >Xc2. Moreover, in embodiments, the second dichroic beam splitter may be configured to provide (at least part of) the second part of the second luminescent material light (via one or more optical elements) back to the second luminescent material. Further, in embodiments, the beam combiner may be configured in a light-receiving relationship with the diffuser. Additionally or alternatively, in embodiments, the beam combiner may be configured in a light-receiving relationship with the first dichroic beam splitter. Additionally or alternatively, in embodiments, the beam combiner may be configured in a light-receiving relationship with the second dichroic beam splitter. Hence, in embodiments, the beam combiner may be configured to combine the diffused first device light (received by the diffuser), the first part of the first luminescent material light (received by the diffuser), and the first part of the second luminescent material light (received by the diffuser) into a beam of system light. Furthermore, in embodiments, in an operational mode of the light generating system the system light may be white light. Especially, in embodiments, the system light may be white light having a correlated color temperature selected from the range of 2000-9000 K. Additionally or alternatively, in embodiments, the system light may be white light having a color rendering index of at least 70. Hence, in embodiments, the invention provides a light generating system configured to provide system light; the light generating system comprising light generating devices, a first luminescent material, a second luminescent material, dichroic mirrors, a beam combiner, and a diffuser, wherein: (A) each of the light generating devices comprise a solid-state light source selected from the group comprising a light-emitting diode, a laser diode, and a superluminescent diode; wherein the light generating devices comprise a first light generating device configured to generate first device light, a second light generating device configured to generate second device light, and a third light generating device configured to generate third device light; wherein the first device light, the second device light, and the third device light each have a centroid wavelength individually selected from the wavelength range of 440-490 nm; (B) the diffuser is configured in a light-receiving relationship with the first light generating device and is configured to diffuse first device light received by the diffuser into diffused first device light; (C) the first luminescent material is configured in a light-receiving relationship with the second light generating device and is configured to convert second device light received by the first luminescent material into first luminescent material light having a first peak emission wavelength ( I ) selected from the wavelength range of 500-540 nm; (C) the second luminescent material is configured in a light-receiving relationship with the third light generating device and is configured to convert the third device light received by the second luminescent material into second luminescent material light having a second peak emission wavelength (X2) selected from the wavelength range of 540-590 nm; (D) the dichroic mirrors comprise a first dichroic beam splitter having a first cut-off wavelength (Xci), and a second dichroic beam splitter having a second cut-off wavelength (Xci); wherein Xci Xc2; wherein: (a) the first dichroic beam splitter is configured in a light-receiving relationship with the first luminescent material and is configured (i) to transmit a first part of the first luminescent material light having a wavelength selected from the range of <Xci and to reflect a second part of the first luminescent material light having a wavelength selected from the range of >Xci, or (ii) to reflect the first part of the first luminescent material light having a wavelength selected from the range of <Xci and to transmit the second part of the first luminescent material light having a wavelength selected from the range of >Xci; and (b) the second dichroic beam splitter is configured in a lightreceiving relationship with the second luminescent material and is configured (i) to transmit a first part of the second luminescent material light having a wavelength selected from the range of <><2 and to reflect a second part of the second luminescent material light having a wavelength selected from the range of >Xc2, or (ii) to reflect the first part of the second luminescent material light having a wavelength selected from the range of <Xc2 and to transmit the second part of the second luminescent material light having a wavelength selected from the range of >> 2; wherein the second dichroic beam splitter is configured to provide the second part of the second luminescent material light (via one or more optical elements) back to the second luminescent material; (E) the beam combiner is configured in a light-receiving relationship with the diffuser, the first dichroic beam splitter, and the second dichroic beam splitter; wherein the beam combiner is configured to combine the diffused first device light, the first part of the first luminescent material light, and the first part of the second luminescent material light received by the beam combiner into a beam of system light; and (F) in an operational mode of the light generating system the system light is white light having a correlated color temperature selected from the range of 2000-9000 K and a CRI of at least 70.

[0012] With such a system a high power light engine may be provided. Further, such system may allow improved performance regarding thermal and photo quenching. Using the proposed reflection characteristics of the different dichroic mirrors a CRI of about 90 can be obtained with a positive R9 value. An R9 value especially represents the accuracy with which a light source or light generating system can produce red light. Such values may be achieved as embodiments of the invention may provide a laser-phosphor high-brightness high-quality white light source comprising diffused blue laser light, green filtered LuAG light, red filtered converted and reconverted YAG light, and optionally far-red filtered re-reconverted phosphor light, and a method of CCT control. Especially, for such a light generating system the color point may easily be adjusted by the user, based on maximum output power of the laser light sources for any of the color points selected in a predetermined range of white light output color points (e.g. 6000 - 10000 K), while the system may provide relatively efficient collection of all the spectral contributions to the output light, resulting in a high efficiency high brightness white light engine. Further, such a light generating system may provide a light engine configured to make effective use of its light sources. Further, such a system can be easily factory-calibrated with respect to a requested color point.

[0013] Yet, such system may in a safe way provide high power light. The system may be relatively compact. Yet, thermal management of the luminescent material may also be provided with this system. In addition to high optical power, the system may also provide high radiance (or luminance), i.e., a high optical power density of the source. The light generating system (or “system”) may thus comprise light generating devices, a first luminescent material, a second luminescent material, dichroic mirrors, a beam combiner, and a diffuser. Here below, embodiments of the different components of the light generating system will be described in further detail.

[0014] The light generating devices may be configured to generate device light. In embodiments, the light generating devices may comprise (at least) a first light generating device, a second light generating device, and a third light generating device. The first light generating device may, in embodiments, be configured to generate first device light. Therefore, in embodiments, the first light generating device may comprise a first light source configured to generate first light source light. The first light source may be essentially any light source, see also further below. Especially, in embodiments, the (first light source of the) first light generating device may comprise a first solid state light source. Hence, in embodiments, the first light generating device may comprise one or more of a light emitting diode (such as a single-junction light emitting diode or multi-junction light-emitting diode), a laser diode, and a superluminescent diode. The first light generating device may herein also comprise a plurality of first (solid state) light sources. Especially, in specific embodiments, the first light generating device may comprise a first laser bank comprising a plurality of first lasers. A laser bank may comprise a relatively dense assembly of multiple laser diodes on a shared substrate provided with collimating optics, such as collimating lenses comprising one lens per laser diode. The use of laser banks may especially be convenient for projecting a beam of high power laser light onto a luminescent converter without the need for using an inverse beam expander. Further, in embodiments, the first light generating device may especially be configured to generate first device light having a first centroid wavelength (ADI). Especially, in embodiments, the first device light may have a first centroid wavelength (ADI) selected from the wavelength range of 430-490 nm, such as from the range of 440-490 nm, like from the range of 445-475 nm. The term “centroid wavelength”, also indicated as Ac, is known in the art, and refers to the wavelength value where half of the light energy is at shorter and half the energy is at longer wavelengths; the value is stated in nanometers (nm). It is the wavelength that divides the integral of a spectral power distribution into two equal parts as expressed by the formula Ac = S A*I(A) / (S 1(A)), where the summation is over the wavelength range of interest, and 1(A) is the spectral energy density (i.e. the integration of the product of the wavelength and the intensity over the emission band normalized to the integrated intensity). The centroid wavelength may e.g. be determined at operation conditions. Hence, in embodiments, the first device light may be blue light. Analogously to the first light generating device, the second light generating device may, in embodiments, be configured to generate second device light. Therefore, in embodiments, the second light generating device may comprise a second light source configured to generate second light source light. The second light source may be essentially any light source, see also further below. Especially, in embodiments, the (second light source of the) second light generating device may comprise a second solid state light source. Hence, in embodiments, the second light generating device may comprise one or more of a light emitting diode (such as a single-junction light emitting diode or multi -junction light-emitting diode), a laser diode, and a superluminescent diode. The second light generating device may herein also comprise a plurality of second (solid state) light sources. Especially, in specific embodiments, the second light generating device may comprise a second laser bank comprising a plurality of second lasers. Further, in embodiments, the second light generating device may especially be configured to generate second device light having a second centroid wavelength (X©2). Especially, in embodiments, the second device light may have a second centroid wavelength (X©2) selected from the wavelength range of 430-490 nm, such as from the range of 440-490 nm, like from the range of 445-475 nm. Hence, in embodiments, the second device light may be blue light.

[0015] Similarly, in embodiments, the third light generating device may be configured to generate third device light. Therefore, in embodiments, the third light generating device may comprise a third light source configured to generate third light source light. The third light source may be essentially any light source, see also further below. Especially, in embodiments, the (third light source of the) third light generating device may comprise a third solid state light source. Hence, in embodiments, the third light generating device may comprise one or more of a light emitting diode (such as a single-junction light emitting diode or multi -junction light-emitting diode), a laser diode, and a superluminescent diode. The third light generating device may herein also comprise a plurality of second (solid state) light sources. Especially, in specific embodiments, the third light generating device may comprise a third laser bank comprising a plurality of third lasers. Further, in embodiments, the third light generating device may especially be configured to generate third device light having a third centroid wavelength (X©3). Especially, in embodiments, the third device light may have a third centroid wavelength (XD3) selected from the wavelength range of 430-490 nm, such as from the range of 440-490 nm, like from the range of 445-475 nm. Hence, in embodiments, the third device light may be blue light. In embodiments, two of, or even all of, the first centroid wavelength (ADI), the second centroid wavelength (ADI), and the third centroid wavelength ( DI) may be essentially the same, i.e., the centroid wavelengths of the first device light, the second device light, and the third device light may mutually differ by zero. However, in other embodiments, two of, or even all of, the first centroid wavelength ( DI), the second centroid wavelength (ADI), and the third centroid wavelength ( DI) may mutually differ. In specific embodiments, the centroid wavelengths of the first device light, the second device light, and the third device light may mutually differ by less than 15 nm, such as by less than 10 nm, like by less than 8 nm, especially by less than 5 nm.

[0016] In an operational mode of the light generating system, the first light generating device may be configured upstream of the diffuser. Especially, in embodiments, the first light generating device may be configured to provide first device light to the diffuser. Hence, in such embodiments, the diffuser may be configured in a light-receiving relationship with the first light generating device. The diffuser may, in embodiments, be configured to diffuse (or scatter) light received by the diffuser. The phrase “... light received by ...”, and similar phrases, such as “device light received by the diffuser” may especially indicate that when the light is actually received by an item, an action may take place. The action may in embodiments be one or more of diffusion, conversion, reflection, and transmission. Further, the action may also include refraction. Furthermore, the phrase “. . . configured in a lightreceiving relationship with . . .”, and similar phrases, such as “element A may be configured in a light-receiving relationship with element B” may especially indicate that light from element B may directly or indirectly (e.g. via one or more optical elements) propagate to (and especially be received by) element A.

[0017] Especially, in embodiments, the diffuser may be configured to diffuse (at least part of) the first device light received by the diffuser into diffused first device light. In embodiments, the diffuser may be configured to diffuse at least 60%, such as at least 70%, like at least 80%, especially at least 90%, more especially at least 95%, including 100% of the first device light received by the diffuser into diffused first device light. Furthermore, in embodiments, the diffuser may be configured to diffuse at most 100%, such as at most 99%, like at most 98%, especially at most 95%, more especially at most 90% of the first device light received by the diffuser into diffused first device light. The diffuser may be configured in the transmissive mode and / or in the reflective mode, see further below.

[0018] The terms “upstream” and “downstream” relate to an arrangement of items or features relative to the propagation of the light from a light generating means (here the especially the light source), wherein relative to a first position within a beam of light from the light generating means, a second position in the beam of light closer to the light generating means is “upstream”, and a third position within the beam of light further away from the light generating means is “downstream”.

[0019] Similarly to the above described, in an operational mode of the light generating system, the second light generating device may be configured upstream of the first luminescent material. Especially, in embodiments, the second light generating device may be configured to provide second device light to the first luminescent material. Hence, in such embodiments, the first luminescent material may be configured in a light-receiving relationship with the second light generating device. The first luminescent material may, in embodiments, be configured to convert light received by the first luminescent material. Especially, in embodiments, the first luminescent material may be configured to convert (at least part of) the second device light received by the first luminescent material into first luminescent material light. In embodiments, the first luminescent material may be configured to convert at least 60%, such as at least 70%, like at least 80%, especially at least 90%, more especially at least 95%, including 100% of the second device light received by the first luminescent material into first luminescent material light. Furthermore, in embodiments, the first luminescent material may be configured to convert at most 100%, such as at most 99%, like at most 98%, especially at most 95%, more especially at most 90% of the second device light received by the first luminescent material into first luminescent material light. Luminescent materials and embodiments comprising such are discussed in more detail (see further below).

[0020] The first luminescent material may be configured in the transmissive mode and / or in the reflective mode. Especially, the luminescent material may be configured in the transmissive mode. In embodiments, when an element is configured in the transmissive mode (or “configured to transmit”) this may indicate that said element may transmit at least 85%, such as at least 90%, like at least 95%, especially at least 98%, including 100% of the light received (and optionally converted) by said element. In the transmissive mode, it may be relatively easy to have light source light admixed in the luminescent material light, which may be useful for generating the desirable spectral power distribution. In the reflective mode, thermal management may be easier, as a substantial part of the luminescent material may be in thermal contact with a thermally conductive element, like a heatsink or heat spreader. In embodiments, when an element is configured in the reflective mode (or “configured to reflect”) this may indicate that said element may reflect at least 85%, such as at least 90%, like at least 95%, especially at least 98%, including 100% of the light received (and optionally converted) by said element.

[0021] In embodiments, the first luminescent material light may have a first peak emission wavelength ( i). Herein the term “peak emission wavelength” may refer to the wavelength where the emission spectrum of the respective element may be reach its maximum. Hence, the first peak emission wavelength ( i) may refer to the wavelength that where the emission spectrum of the first luminescent material may reach its maximum, i.e., may peak. The first peak emission wavelength ( i) may especially be selected from the wavelength range of 490-560 nm, such as from the wavelength range of 500-540 nm, like from the wavelength range of 510-530 nm. Hence, in embodiments, the first luminescent material may be configured to convert blue second device light into green-yellow first luminescent material light.

[0022] As described above, in embodiments, the first light generating device may be configured to provide first device light to the diffuser and the second light generating device may be configured to provide second device light to the first luminescent material. However, in other embodiments, the first light generating device and the second light generating device may be essentially the same light generating device. Hence, in such embodiments, there may be one light generating device configured to provide device light (optionally via one or more optics) to both the diffuser and the first luminescent material, i.e., the diffuser and the first luminescent material may be configured in light-receiving relationships with essentially the same light generating device.

[0023] Analogously, in an operational mode of the light generating system, the third light generating device may be configured upstream of the second luminescent material. Especially, in embodiments, the third light generating device may be configured to provide third device light to the second luminescent material. Hence, in such embodiments, the second luminescent material may be configured in a light-receiving relationship with the third light generating device. The second luminescent material may, in embodiments, be configured to convert light received by the second luminescent material. Especially, in embodiments, the second luminescent material may be configured to convert (at least part of) the third device light received by the second luminescent material into second luminescent material light. In embodiments, the second luminescent material may be configured to convert at least 60%, such as at least 70%, like at least 80%, especially at least 90%, more especially at least 95%, including 100% of the third device light received by the second luminescent material into second luminescent material light. Furthermore, in embodiments, the second luminescent material may be configured to convert at most 100%, such as at most 99%, like at most 98%, especially at most 95%, more especially at most 90% of the third device light received by the second luminescent material into second luminescent material light. The second luminescent material may be configured in the transmissive mode and / or in the reflective mode.

[0024] In embodiments, the second luminescent material light may have a second peak emission wavelength ( 2). The second peak emission wavelength ( 2) may especially be selected from the wavelength range of 540-620 nm, such as from the wavelength range of 540-590 nm, like from the wavelength range of 550-580 nm. Hence, in embodiments, the second luminescent material may be configured to convert blue third device light into yellow-red second luminescent material light.

[0025] Thus, in embodiments, the third light generating device may be configured to provide third device light to the second luminescent material. However, in embodiments, two or more of the first light generating device, the second light generating device, and the third light generating device may be essentially the same light generating device. Hence, in such embodiments, there may be one light generating device configured to provide device light (optionally via one or more optics) to two (or even all) of the diffuser, the first luminescent material, and the second luminescent material, i.e., two (or even all) of the diffuser, the first luminescent material, and the third luminescent material may be configured in light-receiving relationships with essentially the same light generating device.

[0026] As described above, the light generating system further comprises dichroic mirrors. In embodiments, the dichroic mirrors may comprise a first dichroic beam splitter and a second dichroic beam splitter. The first dichroic beam splitter may, in embodiments, have a first cut-off wavelength ( ci). Hence, in embodiments, the first dichroic beam splitter may be configured (i) to reflect or transmit light having a wavelength smaller than (or optionally equal to) the first cut-off wavelength ( ci), and (ii) to transmit of reflect light having a wavelength larger than (or optionally equal to) the first cut-off wavelength ( ci). In specific embodiments, the first cut-off wavelength ( ci) may be selected from the wavelength range of 555-585 nm, such as from the wavelength range of 560-580 nm, like from the wavelength range of 560-570 nm.

[0027] The first dichroic beam splitter may further, in embodiments, be configured downstream of the first luminescent material. As such, in an operational mode of the light generating system, the first dichroic beam splitter may be configured in a light-receiving relationship with the first luminescent material. The first dichroic beam splitter may especially be configured to transmit (at least part of) the first luminescent material light received by the first dichroic beam splitter and to reflect (at least another part) of the first luminescent material light received by the first dichroic beam splitter. In embodiments, the luminescent material light received by the first dichroic beam splitter may comprise a first part and a second part. The first part of the first luminescent material light received by the first dichroic beam splitter may, in embodiments, have a wavelength smaller than (or optionally equal to) the first cut-off wavelength, i.e., < ci. In specific embodiments, the first part of the first luminescent material light may comprise substantially green light. The second part of the first luminescent material light received by the first dichroic beam splitter may, in embodiments, have a wavelength larger than (or optionally equal to) the first cut-off wavelength, i.e., > ci. In specific embodiments, the first part of the first luminescent material light may comprise substantially yellow light. In embodiments, the first dichroic beam splitter may thus be configured (i) to transmit (at least part of) the first part of the first luminescent material light (received by the first dichroic beam splitter and) having a wavelength selected from the range of < ci, and (ii) to reflect (at least part of) the second part of the first luminescent material light (received by the first dichroic beam splitter and) having a wavelength selected from the range of > ci. Alternatively, in embodiments, the first dichroic beam splitter may thus be configured (i) to reflect (at least part of) the first part of the first luminescent material light (received by the first dichroic beam splitter and) having a wavelength selected from the range of < ci, and (ii) to transmit (at least part of) the second part of the first luminescent material light (received by the first dichroic beam splitter and) having a wavelength selected from the range of >Xci. For example, in embodiments, the first cut-off wavelength ( ci) may be 564 nm. Hence, in such embodiments, the first dichroic beam splitter may be configured (i) to transmit (or reflect) first luminescent material light (received by the first dichroic beam splitter and) having a wavelength selected from the wavelength range of <564 nm, and (ii) to reflect (or transmit) first luminescent material light (received by the first dichroic beam splitter and) having a wavelength selected from the wavelength range of >564 nm.

[0028] The first dichroic beam splitter may be configured such that light reflected by the first dichroic beam splitter may not be reflected back to the first luminescent material. However, in alternative embodiments, the first dichroic beam splitter may yet be configured such that light reflected by the first dichroic beam splitter is reflected back to the first luminescent material, see also further below for the second (and third) dichroic beam splitter. Similarly to the first dichroic beam splitter, in embodiments, the second dichroic beam splitter may have a second cut-off wavelength ( ci). Hence, in embodiments, the second dichroic beam splitter may be configured (i) to reflect or transmit light having a wavelength smaller than (or optionally equal to) the second cut-off wavelength ( ci), and (ii) to transmit of reflect light having a wavelength larger than (or optionally equal to) the second cut-off wavelength ( ci). In embodiments, the second cut-off wavelength ( ci) may especially be different from the first cut-off wavelength ( ci), i.e., ci ci. However, this may not necessarily be the case, i.e., in some alternative embodiments, the second cut-off wavelength ( ci) may be essentially the same as the first cut-off wavelength ( ci). In specific embodiments, the second cut-off wavelength ( ci) may be selected from the wavelength range of 560-590 nm, such as from the wavelength range of 565-585 nm, like from the wavelength range of 575-585 nm.

[0029] The second dichroic beam splitter may further, in embodiments, be configured downstream of the second luminescent material. As such, in an operational mode of the light generating system, the second dichroic beam splitter may be configured in a light-receiving relationship with the second luminescent material. The second dichroic beam splitter may especially be configured to transmit (at least part of) the second luminescent material light received by the second dichroic beam splitter and to reflect (at least another part) of the second luminescent material light received by the second dichroic beam splitter. In embodiments, the luminescent material light received by the second dichroic beam splitter may comprise a first part and a second part. The first part of the second luminescent material light received by the second dichroic beam splitter may, in embodiments, have a wavelength smaller than (or optionally equal to) the second cut-off wavelength, i.e., <> 2. In specific embodiments, the first part of the first luminescent material light may comprise substantially red light. The second part of the second luminescent material light received by the second dichroic beam splitter may, in embodiments, have a wavelength larger than (or optionally equal to) the second cut-off wavelength, i.e., >> 2. In specific embodiments, the first part of the first luminescent material light may comprise substantially yellow light. In embodiments, the second dichroic beam splitter may thus be configured (i) to transmit (at least part of) the first part of the second luminescent material light (received by the second dichroic beam splitter and) having a wavelength selected from the range of <> 2, and (ii) to reflect (at least part of) the second part of the second luminescent material light (received by the second dichroic beam splitter and) having a wavelength selected from the range of >> 2. Alternatively, in embodiments, the second dichroic beam splitter may thus be configured (i) to reflect (at least part of) the first part of the second luminescent material light (received by the second dichroic beam splitter and) having a wavelength selected from the range of <> 2, and (ii) to transmit (at least part of) the second part of the second luminescent material light (received by the second dichroic beam splitter and) having a wavelength selected from the range of >> 2. For example, in embodiments, the second cut-off wavelength ( ci) may be 580 nm. Hence, in such embodiments, the second dichroic beam splitter may be configured (i) to transmit (or reflect) second luminescent material light (received by the second dichroic beam splitter and) having a wavelength selected from the wavelength range of <580 nm, and (ii) to reflect (or transmit) second luminescent material light (received by the second dichroic beam splitter and) having a wavelength selected from the wavelength range of >580 nm.

[0030] The second dichroic beam splitter may, in embodiments, be configured such that light reflected by the second dichroic beam splitter may be reflected back to the second luminescent material. Configuring the second dichroic beam splitter such that light reflected by the second dichroic beam splitter is reflected back to the second luminescent material may be advantageous because said light may be re-converted to increase the amount of second luminescent material light (having a desired wavelength relative to the second cut-off wavelength ( ci)) in the output system light. Thus, in embodiments, the second dichroic beam splitter may be configured to provide (at least part of) the second part of the second luminescent material light (via one or more optical elements) back to the second luminescent material. Hence, the second part of the second luminescent material light is being prevented from propagating through the system and either interfering with or escaping the light generating system, improving safe operation of the light generating system. In such embodiments, the second luminescent material may be configured to re-convert (at least part of) the second part of the second luminescent material light received by the second luminescent material light (such that the contribution of the first part of second luminescent material light may be increased). In specific embodiments, the second dichroic beam splitter may be configured to reflect the second (especially yellow) part of the second luminescent material light back to the second luminescent material such that at least part of the reflected second (yellow) part of the luminescent material light may be re-converted by the second luminescent material into the first (red) part of the second luminescent material light.

[0031] The light generating system may thus, in embodiments, in an operational mode be configured to generate one or more of (blue) diffused first device light, (green) first luminescent material light, and (red) second luminescent material light. The different types of light may be combined into a beam of system light. Therefore, in embodiments, the light generating system may comprise a beam combiner. In embodiments, in an operational mode of the light generating system the beam combiner may be configured downstream of the diffuser, the first dichroic beam splitter, and the second dichroic beam splitter. Hence, in embodiments, the beam combiner may be configured in a light-receiving relationship with (one or more of, especially all of) the diffuser, the first dichroic beam splitter, and the second dichroic beam splitter. The beam combiner may especially be configured to combine (at least) the diffused first device light received by the beam combiner, the first part of the first luminescent material light received by the beam combiner, and the second part of the second luminescent material light received by the beam combiner into a beam of system light.

[0032] The system light may thus, in an operational mode of the light generating system, be white light. Especially, in embodiments, the system light may be white light having a CCT selected from the range of 1000-12000 K, such as from the range of 2000- 9000 K, like from the range of 2500-8000 K, especially from the range of 6500-8000 K. The term “white light”, and similar terms, herein, are known to the person skilled in the art. It may especially relate to light having a correlated color temperature (CCT) between about 1800 K and 20000 K, such as between 2000 and 20000 K, especially 2700-20000 K, for general lighting especially in the range of about 2000-7000 K, such as in the range of 2700 K and 6500 K. In embodiments, e.g. for backlighting purposes, or for other purposes, the correlated color temperature (CCT) may especially be in the range of about 7000 K and 20000 K. Yet further, in embodiments the correlated color temperature (CCT) is especially within about 15 SDCM (standard deviation of color matching) from the BBL (black body locus), especially within about 10 SDCM from the BBL, even more especially within about 5 SDCM from the BBL. In specific embodiments, the correlated color temperature (CCT) may be selected from the range of 6000-12000 K, like selected from the range of 7000-12000 K, like at least 8000 K. Additionally or alternatively, in embodiments, the system light may be white light having a color rendering index (CRI) of at least 65, such as at least 70, like at least 80, especially at least 85. Especially, in embodiments the correlated color temperature (CCT) may be selected from the range of 6000-12000 K, like selected from the range of 7000-12000 K, in combination with a CRI of at least 70.

[0033] In an embodiment, the light source(s) may also provide light source light having a correlated color temperature (CCT) between about 5000 and 20000 K, e.g. direct phosphor converted LEDs (blue light emitting diode with thin layer of phosphor for e.g. obtaining of 10000 K). Hence, in a specific embodiment the light source is configured to provide light source light with a correlated color temperature in the range of 5000-20000 K, even more especially in the range of 6000-20000 K, such as 8000-20000 K. An advantage of the relative high color temperature may be that there may be a relatively high blue component in the light source light.

[0034] As indicated above, the light generating system may comprise a first luminescent material and a second luminescent material (and optionally even a third luminescent material, see also further below). The luminescent material is configured to convert at least part of first radiation (selected from one or more of UV radiation and visible radiation), into luminescent material light. Especially, in embodiments the luminescent material may be configured to convert at least part of blue light (as radiation) into luminescent material light. Especially when blue light is partly converted, the blue light may be used as source of blue light (for the device light) and as excitation light that can be converted by the luminescent material. The first radiation may especially be provided by a (solid state) light source.

[0035] When different luminescent materials are applied, one or more luminescent materials may be configured to convert incident light into one or more of green and yellow luminescent material light, and one or more other luminescent materials may be configured to convert incident light into one or more of orange and red luminescent material light.

[0036] The term “luminescent material” especially refers to a material that can convert first radiation, especially one or more of UV radiation and blue radiation, into second radiation. In general, the first radiation and second radiation have different spectral power distributions. Hence, instead of the term “luminescent material”, also the terms “luminescent converter” or “converter” may be applied. Further, instead of the term “luminescent material” also the term “phosphor” may be applied. These terms are known to the person skilled in the art. In general, the second radiation has a spectral power distribution at larger wavelengths than the first radiation, which is the case in the so-called down-conversion. In specific embodiments, however the second radiation has a spectral power distribution with intensity at smaller wavelengths than the first radiation, which is the case in the so-called up- conversion.

[0037] In embodiments, the “luminescent material” may especially refer to a material that can convert radiation into e.g. visible and / or infrared light. For instance, in embodiments the luminescent material may be able to convert one or more of UV radiation and blue radiation, into visible light. The luminescent material may in specific embodiments also convert radiation into infrared radiation (IR). Hence, upon excitation with radiation, the luminescent material emits radiation. In general, the luminescent material will be a down converter, i.e. radiation of a smaller wavelength is converted into radiation with a larger wavelength (Xex<em), though in specific embodiments the luminescent material may comprise up-converter luminescent material, i.e. radiation of a larger wavelength is converted into radiation with a smaller wavelength (%x>%m).

[0038] In embodiments, the term “luminescence” may refer to phosphorescence. In embodiments, the term “luminescence” may also refer to fluorescence. Instead of the term “luminescence”, also the term “emission” may be applied. Hence, the terms “first radiation” and “second radiation” may refer to excitation radiation and emission (radiation), respectively. Likewise, the term “luminescent material” may in embodiments refer to phosphorescence and / or fluorescence. The term “luminescent material” may also refer to a plurality of different luminescent materials. Examples of possible luminescent materials are indicated below. Hence, the term “luminescent material” may in specific embodiments also refer to a luminescent material composition. The term “luminescent material” herein may also refer to a material comprising a luminescent material, such as a light transmissive host comprising the luminescent material.

[0039] In embodiments, luminescent materials are selected from garnets and nitrides, especially doped with trivalent cerium or divalent europium, respectively. The term “nitride” may also refer to oxynitride or nitridosilicate, etc. Alternatively or additionally, the luminescent material(s) may be selected from silicates, especially doped with divalent europium.

[0040] Especially, the luminescent material is configured to convert at least part of the light source light into luminescent material light, wherein the luminescent material may comprise a (garnet) luminescent material of the type A^B O^ Ce, wherein A comprises one or more of Y, La, Gd, Tb and Lu, and wherein B comprises one or more of Al, Ga, In and Sc. Hence, the luminescent material light may e.g. be green light or yellow light (or in specific embodiments even orange (dependent upon the composition of the garnet and cerium concentration)). However, other embodiments are also possible, see below. In embodiments, 0.05-10% of the A elements comprise Ce, even more especially 0.05-5%, such as 0.1-5%. Especially, embodiments, 0.1-3% of the A elements comprise Ce, such as up to 2%, like selected from the range of 0.1-1.5%, such as at least above 0.5%.

[0041] Especially, a luminescent material comprises conversion material or is a conversion material. The luminescent material may comprise an organic group that converts the light, or a molecule that converts the light, or an inorganic group that converts the light, etc. Such groups (or molecule) may be indicated as converter element. The garnet type material as indicated above, comprises cerium (Ce) as converter element. Cerium comprising garnets are well known in the art.

[0042] Hence, in specific embodiments the luminescent material comprises a luminescent material of the type A^B O^Ce, wherein A in embodiments comprises one or more of Y, La, Gd, Tb and Lu, especially (at least) one or more of Y, Gd, Tb and Lu, and wherein B in embodiments comprises one or more of Al, Ga, In and Sc. Especially, A may comprise one or more of Y, Gd and Lu, such as especially one or more of Y and Lu. Especially, B may comprise one or more of Al and Ga, more especially at least Al, such as essentially entirely Al. Hence, especially suitable luminescent materials are cerium comprising garnet materials. Embodiments of garnets especially include A3B5O12 garnets, wherein A comprises at least yttrium or lutetium and wherein B comprises at least aluminum. Such garnets may be doped with cerium (Ce), with praseodymium (Pr) or a combination of cerium and praseodymium; especially however with Ce. Especially, B comprises aluminum (Al), however, B may also partly comprise gallium (Ga) and / or scandium (Sc) and / or indium (In), especially up to about 20% of Al, more especially up to about 10 % of Al (i.e. the B ions essentially consist of 90 or more mole % of Al and 10 or less mole % of one or more of Ga, Sc and In); B may especially comprise up to about 10% gallium. In another variant, B and O may at least partly be replaced by Si and N. The element A may especially be selected from the group consisting of yttrium (Y), gadolinium (Gd), terbium (Tb) and lutetium (Lu). Further, Gd and / or Tb are especially only present up to an amount of about 20% of A. In a specific embodiment, the garnet luminescent material comprises (Yi-xLux^BsOn Ce, wherein x is equal to or larger than 0 and equal to or smaller than 1. The term “:Ce”, indicates that part of the metal ions (i.e. in the garnets: part of the “A” ions) in the luminescent material is replaced by Ce. For instance, in the case of (Yi-xLuxfALO^Ce, part of Y and / or Lu is replaced by Ce. This is known to the person skilled in the art. Ce will replace A in general for not more than 10%; in general, the Ce concentration will be in the range of 0.1 to 4%, especially 0.1 to 2% (relative to A). Assuming 1% Ce and 10% Y, the full correct formula could be (Yo.iLuo.89Ceo.oi)3Al5Oi2. Ce in garnets is substantially or only in the trivalent state, as is known to the person skilled in the art. In embodiments, the luminescent material (thus) comprises A3B5O12 wherein in specific embodiments at maximum 10% of B-0 may be replaced by Si-N.

[0043] In specific embodiments the luminescent material comprises (YXI-X2- x3A’x2Cex3)3(Alyi.y2B’y2)5Oi2, wherein xl+x2+x3=l, wherein x3>0, wherein 0<x2+x3<0.2, wherein yl+y2=l, wherein 0<y2<0.2, wherein A’ comprises one or more elements selected from the group consisting of lanthanides, and wherein B’ comprises one or more elements selected from the group consisting of Ga, In and Sc. In embodiments, x3 is selected from the range of 0.001-0.1.

[0044] In specific embodiments at maximum 10% of B-0 may be replaced by Si-N. Here, B in B-0 refers to one or more of Al, Ga, In and Sc (and O refers to oxygen); in specific embodiments B-0 may refer to Al-O. As indicated above, in specific embodiments x3 may be selected from the range of 0.001-0.04. Especially, such luminescent materials may have a suitable spectral distribution (see however below), have a relatively high efficiency, have a relatively high thermal stability, and allow a high CRI (optionally in combination with (the) light of other sources of light as described herein). Hence, in specific embodiments A may be selected from the group consisting of Lu and Gd. Alternatively or additionally, B may comprise Ga. Hence, in embodiments the luminescent material comprises (YXI-X2-X3(Lu,Gd)x2CeX3)3(Alyi.y2Gay2)5Oi2, wherein Lu and / or Gd may be available. Even more especially, x3 is selected from the range of 0.001-0.1, wherein 0<x2+x3<0.1, and wherein 0<y2<0.1. Further, in specific embodiments, at maximum 1% of B-0 may be replaced by Si- N. Here, the percentage refers to moles (as known in the art); see e.g. also EP3149108. In yet further specific embodiments, the luminescent material comprises (Yxi-x3CeX3)3A150i2, wherein xl+x3=l, and wherein 0<x3<0.2, such as 0.001-0.1.

[0045] Alternatively or additionally, the luminescent material may comprise a luminescent material of the type A3SieNn:Ce3+, wherein A comprises one or more of Y, La, Gd, Tb and Lu, such as in embodiments one or more of La and Y.

[0046] In specific embodiments, the luminescent material may comprise at least two different luminescent materials configured to provide luminescent material light having different spectral power distributions. As can be derived from the above, the term “different luminescent materials” may refer to luminescent materials that are different, or to two compositions, each including at least one luminescent material in common, but wherein the compositions differ. For instance, a primary luminescent material comprising luminescent materials A and B, and a secondary luminescent material comprising only A or only B, or comprising both A and B, but in a different weight ratio. Such primary luminescent material and secondary luminescent material may have different spectral power distributions of their respective luminescent material light.

[0047] The garnet type luminescent material may also be described with an alternative formula A3B’2C”30i2. Here, A may comprise one or more of (i) rare earth ions, such as one or more selected from Y3+, Lu3+, Gd3+, Tb3+, La3+, and (ii) divalent cations, such as Ca2+. Here, B may comprise one or more of (i) trivalent cations, such as one or more of Al3+, Ga3+, Sc3+, Sb3+, and In3+, and (ii) divalent cations, such as one or more of Mg2+and Mn2+. Here, C may comprise one or more of (i) trivalent cations, such as one or more of Ga3+and Al3+, (ii) divalent cations, such as Mn2+, and (iii) tetravalent cations, such as one or more of Si4+and Ge4+. With such ions, the garnet crystal structure can be maintained. Other substitutions than mentioned may also be possible.

[0048] Eu in the above (and further below) indicated luminescent materials is substantially or only in the divalent state, as is known to the person skilled in the art.

[0049] The term “luminescent material” herein especially relates to inorganic luminescent materials. Alternatively or additionally, also other luminescent materials may be applied. For instance quantum dots and / or organic dyes may be applied and may optionally be embedded in transmissive matrices like e.g. polymers, like PMMA, or polysiloxanes, etc. etc.. Different luminescent materials may have different spectral power distributions of the respective luminescent material light. Alternatively or additionally, such different luminescent materials may especially have different color points (or dominant wavelengths).

[0050] In embodiments, the first luminescent material may especially comprise a luminescent material of the type A3BsOi2:Ce3+, more especially of the type (¥xiiLuxi2A’xi3Cexi4)3B5Oi2. Conversely, in embodiments, the second luminescent material may especially comprise a luminescent material of the type A3BsOi2:Ce3+, more especially of the type (Y^iLu^A’^Ce^^BsOn. In such embodiments, A’ comprises one or more of La, Gd, and Tb, and wherein B comprises one or more of Al, Ga, In, and Sc. Furthermore, in embodiments, for the first luminescent material comprising (YxnLuxi2A’xi3Cexi4)3B50i2 may apply that xn + X12 + X13 + xi4 = 1. Additionally, in embodiments, for the first luminescent material comprising (YxnLuxi2A’xi3Cexi4)3B50i2 may apply that xn + xn> 0. Yet additionally, in embodiments, for the first luminescent material comprising (YxnLuxi2A’xi3Cexi4)3B5Oi2 may apply that 0 < xi3 < 1, and 0.001 < xi4< 0.1. Conversely, in embodiments, for the second luminescent material comprising (YX2iLuX22A’X23CeX24)3B5Oi2 may apply that X21 + X22 + X23 + X24 = 1. Additionally, in embodiments, for the second luminescent material comprising (YX2iLuX22A’X23CeX24)3B5Oi2 may apply that X21 + X22 > 0. Yet additionally, in embodiments, for the second luminescent material comprising (YX2iLuX22A’X23CeX24)3B5Oi2 may apply that 0 < X23 < 1, and 0.001 < X24< 0.1.

[0051] Furthermore, in embodiments, the first luminescent material may comprise on a molar basis more Lu than the second luminescent material, i.e., X12 > X22. Especially, in embodiments, xn > 1.5*X22, such as xn > 2*X22, especially xn > 3*X22. Further, in embodiments, the second luminescent material may comprise on a molar basis more Y than the first luminescent material, i.e., X21 > xn. Especially, in embodiments, X21 > 1.5*xn, such as X21 > 2*xn, especially X21 > 3*xn. In embodiments, X22 may be equal to zero. Further, in embodiments, xn may be equal to zero. Further yet, in embodiments, one or more of X12, X13, X22 and X23 may be equal to zero. In embodiments, X14 may be equal to X24. Yet, in embodiments, X14 may be different from X24, wherein (both) X14 and X24 may be individually selected from the range of 0.001-0.1. Hence, in specific embodiments, the first luminescent material may comprise a luminescent material of the type (YxiiLuxnA’xBCexu^BsOn and the second luminescent material may comprise a luminescent material of the type (YX2iLux22A’x23Cex24)3B5Oi2, wherein A’ comprises one or more of La, Gd, and Tb, wherein B comprises one or more of Al, Ga, In and Sc; wherein (a) xn + X12 + xi3 + xi4 = 1; xn + xn > 0; 0 < X13 < 1; and 0.001 < xi4< 0.1; (b) X21 + X22 + X23 + X24 = 1; X21 + X22 > 0; 0 < X23 < 1; and 0.001 < X24< 0.1; and (c) xn > X22 and x2i > xn. Such compositions of first luminescent material and second luminescent material may provide a broader spectral power distribution of luminescent material light in the system light, compared to a spectral power distribution of a first luminescent material light and a second luminescent material light provided by a first luminescent material and a second luminescent material comprising essentially the same (or similar) types of luminescent material (e.g., both (YxiiLuxnA’xBCexu^BsOn or both (YX2iLux22A’x23Cex24)3B5Oi2). For instance, in embodiments, the first luminescent material may be configured to provide first luminescent material light, and the second luminescent material may be configured to provide second luminescent material light, wherein (a wavelength range of) a spectral power distribution of the first luminescent material light may overlap (a wavelength range of) a spectral power distribution of the second luminescent material light for < 90%. In specific embodiments, the first luminescent material may comprise Lu3A150i2:Ce3+. Further, in specific embodiments, the second luminescent material may comprise Y3A150i2:Ce3+.

[0052] As described above, in embodiments, at least part of the first luminescent material light may be received by the first dichroic beam splitter. The first dichroic beam splitter may, in embodiments, be configured to provide (at least part of) the first part of the first luminescent material light to the beam combiner. The second part of the first luminescent material light may, in embodiments, not be provided to the beam combiner. Therefore, in some embodiments, the light generating system may comprise a beam dump. In embodiments, the beam dump (or block, or trap) may be configured to absorb a beam of light received by the beam dump. Therefore, in embodiments, the beam dump may comprise a material with relatively strong absorption and relatively low reflectance, such as e.g. a carbon nanotube, anodized aluminum, and / or nickel-phosphate coatings. The beam dump may, in embodiments, be configured downstream of the first dichroic beam splitter, such that the first dichroic beam splitter may be configured to provide (at least part of) the second part of the first luminescent material light received by the first dichroic beam splitter to the beam dump. In embodiments, the first dichroic beam splitter may be configured to provide at least 80%, such as at least 90%, like at least 95%, especially at least 98%, including 100% of the second part of the first luminescent material light received by the first dichroic beam splitter to the beam dump. Hence, in embodiments, the light generating system may comprise a beam dump, wherein the first dichroic beam splitter may be configured to provide (at least part of) the second part of the first luminescent material light to the beam dump. Such embodiments may be beneficial as the beam dump may collect undesired light and prevent it from propagating through the system and either interfering with or escaping the light generating system, improving safe operation of the light generating system. Furthermore, in embodiments, the first dichroic beam splitter may be configured to direct unconverted device light to the beam dump, as luminescent converters such as phosphors generally tend to provide less than 100% conversion of light. Hence, by configuring the first dichroic beam splitter to direct unconverted device light to the beam dump the eye-safety of the light generating system (should one or more components fail) can be improved.

[0053] Additionally or alternatively, in embodiments, the first dichroic beam splitter may be configured to provide (at least part of) the second part of the first luminescent material light received by the first dichroic beam splitter (via one or more optical elements) to the second luminescent material. Hence, in embodiments, the light generating system may comprise one or more optical elements (or “optics”).

[0054] The terms “optics” and “optical elements” may refer to the same items. In embodiments, the one or more optical elements may comprise (specular) reflectors or mirrors. Especially, in embodiments, the optics may also include one or more of mirrors, reflectors, collimators, lenses, prisms, diffusers, phase plates, polarizers, diffractive elements, gratings, dichroics, arrays of one or more of the afore-mentioned, etc. Alternatively or additionally, the term “optics” may refer to a holographic element or a mixing rod. In embodiments, the optics may include one or more of beam expander optics and zoom lens optics. In embodiments, the optics may comprise an integrator, like a “Koehler integrator” (or “Kohler integrator”). In embodiments, at least part of the optical elements may be configured in a light-receiving relationship with the first dichroic beam splitter. Especially, in embodiments, the first dichroic beam splitter may be configured to provide (at least part of) the second part of the first luminescent material light received by the first dichroic beam splitter to the one or more optical elements. The one or more optical elements may then, in embodiments, be configured to guide (such as e.g. direct and / or reflect) (at least part of) the second part of the first luminescent material light to the second luminescent material. As such, in embodiments, the (yellow) second part of the first luminescent material light may be provided to the second luminescent material.

[0055] The second luminescent material may, in embodiments, thus (also) be configured to convert (at least part of) the second part of the first luminescent material light received by the second luminescent material into second luminescent material light. Especially, in embodiments, the second luminescent material may be configured to convert (at least part of) the second part of the first luminescent material light (received by the second luminescent material) in the same or a similar manner as (described above for) the third device light received by the second luminescent material. Hence, in embodiments, the second luminescent material may be configured to convert (at least part of) the (yellow) second part of the first luminescent material light (received by the second luminescent material) into (red) re-converted second luminescent material light. Hence, in embodiments, the light generating system may comprise one or more optical elements, wherein the first dichroic beam splitter may be configured to provide the second part of the first luminescent material light to the one or more optical elements, and wherein the one or more optical elements may be configured to guide the second part of the first luminescent material light to the second luminescent material; wherein the second luminescent material may be configured to convert the second part of the first luminescent material light received by the second luminescent material into second luminescent material light. Such embodiments may be beneficial as the otherwise wasted second part of the first luminescent material light may in such embodiments be used to improve the second luminescent material light output of the second luminescent material, therewith increasing the red contribution in the system light.

[0056] Further, in embodiments, the luminescent materials of the light generating system may comprise a third luminescent material. In embodiments, the third luminescent material may be configured to convert light received by the third luminescent material into third luminescent material light. Especially, in embodiments, the third luminescent material may be configured in a light-receiving relationship with the first dichroic beam splitter. Additionally or alternatively, in embodiments, the third luminescent material may be configured in a light-receiving relationship with the second dichroic beam splitter. As such, in embodiments, the third luminescent material may be configured to convert (at least part of) the second part of the first luminescent material light and / or the second part of the second luminescent material light received by the third luminescent material into third luminescent material light.

[0057] The third luminescent material light may, in embodiments, be combined with the diffused first device light, the first part of the first luminescent material light, and the first part of the second luminescent material light into a beam of system light. Therefore, in embodiments, the dichroic mirrors as described above may also comprise a third dichroic beam splitter. The third dichroic beam splitter may, in embodiments, have a third cut-off wavelength (Xca). Hence, in embodiments, the third dichroic beam splitter may be configured (i) to reflect or transmit light having a wavelength smaller than (or optionally equal to) the third cut-off wavelength (Xca), and (ii) to transmit of reflect light having a wavelength larger than (or optionally equal to) the third cut-off wavelength (Xca). In specific embodiments, the third cut-off wavelength (Xca) may be selected from the wavelength range of 640-710 nm, such as from the wavelength range of 650-700 nm, like from the wavelength range of 675- 700 nm.

[0058] The third dichroic beam splitter may, in embodiments, be configured downstream of the third luminescent material. As such, in an operational mode of the light generating system, the third dichroic beam splitter may be configured in a light-receiving relationship with the third luminescent material. Furthermore, in embodiments, the third dichroic beam splitter may be configured downstream of the first dichroic beam splitter and / or the second dichroic beam splitter. Hence, in such embodiments, the third dichroic beam splitter may be configured (optionally via the one or more optical element) in a lightreceiving relationship with the first dichroic beam splitter and / or the second dichroic beam splitter, respectively. Yet further, in some embodiments, the third dichroic beam splitter may be configured upstream of the beam combiner, i.e., the third dichroic beam splitter may be configured in an optical path between the luminescent materials and the beam combiner. However, in alternative embodiments, the third dichroic beam splitter may (also) be configured downstream of the beam combiner, see also further below.

[0059] In embodiments, the third dichroic beam splitter may be configured (i) to transmit (at least part of) the third luminescent material light received by the third dichroic beam splitter and (ii) to reflect (one or more of) the diffused first device light, the first luminescent material light, and the second luminescent material light received by the third dichroic beam splitter. Alternatively, in embodiments, the third dichroic beam splitter may especially be configured (i) to reflect (at least part of) the third luminescent material light received by the third dichroic beam splitter and (ii) to transmit (one or more of) the diffused first device light, the first luminescent material light, and the second luminescent material light received by the third dichroic beam splitter.

[0060] Furthermore, in embodiments, the beam combiner may be configured in a light-receiving relationship with the third dichroic beam splitter. The beam combiner may especially be configured to combine one or more of the diffused first device light, the first part of the first luminescent material light, the first part of the second luminescent material light, and the third luminescent material light received by the beam combiner into a beam of system (output) light. As such, in embodiments, in an operational mode of the light generating system the system light may thus comprise (at least part of) the third luminescent material light. Hence, in embodiments, the luminescent materials may comprise a third luminescent material; wherein the dichroic mirrors may comprise a third dichroic beam splitter having a third cut-off wavelength (Xo), wherein the third cut-off wavelength (Xo) may be selected from the range of 650-700 nm; wherein the third luminescent material may be configured in a light-receiving relationship with the first dichroic beam splitter and may be configured to convert (at least part of) light received by the third luminescent material into third luminescent material light; and wherein the third dichroic beam splitter may be configured in a light-receiving relationship with the third luminescent material and may be configured (i) to transmit (at least part of) the third luminescent material light and to reflect (one or more of) the diffused first device light, the first luminescent material light and the second luminescent material light, or (ii) to reflect the third luminescent material light and to transmit (one or more of) the diffused first device light, the first luminescent material light and the second luminescent material light; wherein the beam combiner may be configured in a light-receiving relationship with the third dichroic beam splitter; wherein in an operational mode of the light generating system the system light may further comprise (at least part of) the third luminescent material light.

[0061] Such embodiments may be beneficial as the addition of the third luminescent material may improve the spectral power distribution of the white output system light through the introduction of a far-red light contribution (see also further below). Additionally, such embodiments may provide improved tuneability of the CCT of the white system light. In embodiments, the third luminescent material may comprise at least a luminescent material of the type of a divalent europium comprising oxynitride luminescent material or a divalent europium comprising nitride luminescent material. Especially, in embodiments, the third luminescent material may comprise a far-red converting phosphor, such as e.g. a nitride phosphor. Here below some embodiments of such types of luminescent materials are described.

[0062] In embodiments, the luminescent material may comprise one or more of MS:EU2+and / or M2SisN8:Eu2+and / or MAI SiNvEu2-and / or Ca2AlSi3O2Ns:Eu2+, etc., wherein M comprises one or more of Ba, Sr and Ca, especially in embodiments at least Sr. Hence, in embodiments, the 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)2Si5Ns:Eu. In these compounds, europium (Eu) is substantially or only divalent, and replaces one or more of the indicated divalent cations. In general, Eu will not be present in amounts larger than 10% of the cation; its presence will especially be in the range of about 0.5 to 10%, more especially in the range of about 0.5 to 5% relative to the cation(s) it replaces. The term “:Eu”, indicates that part of the metal ions is replaced by Eu (in these examples by Eu2+). For instance, assuming 2% Eu in CaAlSiNvEu, the correct formula could be (Cao.9sEuo.o2)AlSiN3. Divalent europium will in general replace divalent cations, such as the above divalent alkaline earth cations, especially Ca, Sr or Ba. The material (Ba,Sr,Ca)S:Eu can also be indicated as MS:Eu, wherein M is one or more elements selected from the group consisting of barium (Ba), strontium (Sr) and calcium (Ca); especially, M comprises in this compound calcium or strontium, or calcium and strontium, more especially calcium. Here, Eu is introduced and replaces at least part of M (i.e. one or more of Ba, Sr, and Ca). Further, the material (Ba,Sr,Ca)2SisN8:Eu can also be indicated as M2Si5N8:Eu, wherein M is one or more elements selected from the group consisting of barium (Ba), strontium (Sr) and calcium (Ca); especially, M comprises in this compound Sr and / or Ba. In a further specific embodiment, M consists of Sr and / or Ba (not taking into account the presence of Eu), especially 50 to 100%, more especially 50 to 90% Ba and 50 to 0%, especially 50 to 10% Sr, such as Bai. Sro. Si NsEu (i.e. 75 % Ba; 25% Sr). Here, Eu is introduced and replaces at least part of M, i.e. one or more of Ba, Sr, and Ca). Likewise, the material (Ba,Sr,Ca)AlSiN3:Eu can also be indicated as MAlSiNvEu, wherein M is one or more elements selected from the group consisting of barium (Ba), strontium (Sr) and calcium (Ca); especially, M comprises in this compound calcium or strontium, or calcium and strontium, more especially calcium. Here, Eu is introduced and replaces at least part of M (i.e. one or more of Ba, Sr, and Ca). Eu in the above indicated luminescent materials is substantially or only in the divalent state, as is known to the person skilled in the art. Hence, such nitride luminescent materials may also be or comprise converter elements, here especially Eu2+.

[0063] Especially, the luminescent material may be an inorganic luminescent material, such as one or more of the above-described trivalent cerium or divalent europium comprising oxides, oxynitrides, or nitrides.

[0064] In embodiments, a 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)2SisN8:Eu. In these compounds, europium (Eu) is substantially or only divalent, and replaces one or more of the indicated divalent cations. In general, Eu will not be present in amounts larger than 10% of the cation; its presence will especially be in the range of about 0.5 to 10%, more especially in the range of about 0.5 to 5% relative to the cation(s) it replaces. The term “:Eu”, indicates that part of the metal ions is replaced by Eu (in these examples by Eu2+). For instance, assuming 2% Eu in CaAlSiNvEu, the correct formula could be (Cao.9sEuo.o2)AlSiN3. Divalent europium will in general replace divalent cations, such as the above divalent alkaline earth cations, especially Ca, Sr or Ba.

[0065] The material (Ba,Sr,Ca)S:Eu can also be indicated as MS:Eu, wherein M is one or more elements selected from the group consisting of barium (Ba), strontium (Sr) and calcium (Ca); especially, M comprises in this compound calcium or strontium, or calcium and strontium, more especially calcium. Here, Eu is introduced and replaces at least part of M (i.e. one or more of Ba, Sr, and Ca).

[0066] Further, the material (Ba,Sr,Ca)2SisN8:Eu can also be indicated as NESis Eu, wherein M is one or more elements selected from the group consisting of barium (Ba), strontium (Sr) and calcium (Ca); especially, M comprises in this compound Sr and / or Ba. In a further specific embodiment, M consists of Sr and / or Ba (not taking into account the presence of Eu), especially 50 to 100%, more especially 50 to 90% Ba and 50 to 0%, especially 50 to 10% Sr, such as Bai.sSro.sSis Eu (i.e. 75 % Ba; 25% Sr). Here, Eu is introduced and replaces at least part of M, i.e. one or more of Ba, Sr, and Ca).

[0067] Likewise, the material (Ba,Sr,Ca)AlSiN3:Eu can also be indicated as MAlSiNvEu, wherein M is one or more elements selected from the group consisting of barium (Ba), strontium (Sr) and calcium (Ca); especially, M comprises in this compound calcium or strontium, or calcium and strontium, more especially calcium. Here, Eu is introduced and replaces at least part of M (i.e. one or more of Ba, Sr, and Ca). As described above, in embodiments, the light generating system may comprise one or more optical elements. In embodiments, at least part of the optical elements may especially be configured in a light-receiving relationship with the first dichroic beam splitter. Especially, in embodiments, the first dichroic beam splitter may be configured to provide (at least part of) the second part of the first luminescent material light received by the first dichroic beam splitter to the one or more optical elements. The one or more optical elements may then, in embodiments, be configured to guide (such as e.g. direct and / or reflect) (at least part of) the second part of the first luminescent material light to the third luminescent material. As such, in embodiments, the (yellow) second part of the first luminescent material light may be provided to the third luminescent material.

[0068] The third luminescent material may, in embodiments, thus (also) be configured to convert (at least part of) the second part of the first luminescent material light received by the third luminescent material into third luminescent material light. Especially, in embodiments, the third luminescent material may be configured to convert at least 60%, such as at least 70%, like at least 80%, especially at least 90%, more especially at least 95%, including 100% of the second part of the first luminescent material light received by the third luminescent material into third luminescent material light. Furthermore, in embodiments, the first luminescent material may be configured to convert at most 100%, such as at most 99%, like at most 98%, especially at most 95%, more especially at most 90% of the second part of the first luminescent material light received by the third luminescent material into third luminescent material light. Hence, in embodiments, the third luminescent material may be configured to convert (at least part of) the (yellow) second part of the first luminescent material light (received by the third luminescent material) into (red) re-converted third luminescent material light. Hence, in embodiments, the light generating system may comprise one or more optical elements, wherein the first dichroic beam splitter may be configured to provide the second part of the first luminescent material light to the one or more optical elements, and wherein the one or more optical elements may be configured to guide the second part of the first luminescent material light to the third luminescent material; wherein the third luminescent material may be configured to convert the second part of the first luminescent material light received by the third luminescent material into third luminescent material light. Such embodiments may be beneficial as the otherwise wasted second part of the first luminescent material light may in such embodiments be used to improve the third luminescent material light output of the third luminescent material, therewith improving the (far-)red contribution in the system light. As described above, the second luminescent material may provide second luminescent material light to the second dichroic beam splitter, which may be configured to reflect back a part (especially the second part) of the second luminescent material light to the second luminescent material. In a similar way, in embodiments, the dichroic mirrors may comprise a fourth dichroic beam splitter configured in a light-receiving relationship with the third luminescent material. The fourth dichroic beam splitter may thus, in such embodiments, be configured between the third luminescent material and the beam combiner. In embodiments, the fourth dichroic beam splitter may have a fourth cut-off wavelength ( c4). Hence, in embodiments, the fourth dichroic beam splitter may be configured (i) to reflect or transmit light having a wavelength smaller than (or optionally equal to) the fourth cut-off wavelength ( c4), and (ii) to transmit of reflect light having a wavelength larger than (or optionally equal to) the fourth cut-off wavelength ( c4). In embodiments, the fourth cut-off wavelength ( c4) may especially be different from the first cut-off wavelength ( ci), i.e., c4 ci. Additionally or alternatively, in embodiments, the fourth cut-off wavelength ( c4) may especially be different from the second cut-off wavelength ( ci), i.e., Xc4^kc2. However, this may not necessarily be the case, i.e., in some alternative embodiments, the fourth cut-off wavelength ( c4) may be essentially the same as the first cut-off wavelength ( ci) and / or the second cut-off wavelength ( ci). In specific embodiments, the fourth cut-off wavelength ( c4) may be selected from the wavelength range of 640-700 nm, such as from the wavelength range of 650-680 nm, like from the wavelength range of 650-660 nm.

[0069] The fourth dichroic beam splitter may further, in embodiments, be configured downstream of the third luminescent material. As such, in an operational mode of the light generating system, the fourth dichroic beam splitter may be configured in a light-receiving relationship with the third luminescent material. The fourth dichroic beam splitter may especially be configured to transmit (at least part of) the third luminescent material light received by the fourth dichroic beam splitter and to reflect (at least another part) of the third luminescent material light received by the fourth dichroic beam splitter. In embodiments, the luminescent material light received by the fourth dichroic beam splitter may comprise a first part and a second part. The first part of the third luminescent material light received by the fourth dichroic beam splitter may, in embodiments, have a wavelength smaller than (or optionally equal to) the fourth cut-off wavelength, i.e., <Xc4. The second part of the third luminescent material light received by the fourth dichroic beam splitter may, in embodiments, have a wavelength larger (or optionally equal to) than the fourth cut-off wavelength, i.e., >Xc4. In embodiments, the fourth dichroic beam splitter may thus be configured (i) to transmit (at least part of) the first part of the third luminescent material light (received by the fourth dichroic beam splitter and) having a wavelength selected from the range of <Xc4, and (ii) to reflect (at least part of) the second part of the third luminescent material light (received by the fourth dichroic beam splitter and) having a wavelength selected from the range of >Xc4. Alternatively, in embodiments, the fourth dichroic beam splitter may thus be configured (i) to reflect (at least part of) the first part of the third luminescent material light (received by the fourth dichroic beam splitter and) having a wavelength selected from the range of <Xc4, and (ii) to transmit (at least part of) the second part of the third luminescent material light (received by the fourth dichroic beam splitter and) having a wavelength selected from the range of >Xc4.

[0070] The fourth dichroic beam splitter may, in embodiments, be configured such that light reflected by the fourth dichroic beam splitter may be reflected back to the third luminescent material. Configuring the fourth dichroic beam splitter such that light reflected by the fourth dichroic beam splitter is reflected back to the third luminescent material may be advantageous because said light may be re-converted to increase the amount of third luminescent material light (having a desired wavelength relative to the fourth cut-off wavelength ( c4)) in the output system light. Thus, in embodiments, the fourth dichroic beam splitter may be configured to provide (at least part of) the second part of the third luminescent material light (via one or more optical elements) back to the third luminescent material. In such embodiments, the third luminescent material may be configured to re-convert (at least part of) the second part of the third luminescent material light received by the third luminescent material (such that the contribution of the first part of third luminescent material light may be increased). In specific embodiments, the fourth dichroic beam splitter may be configured to reflect the second part of the third luminescent material light back to the second luminescent material such that at least part of the reflected second (far-red) part of the luminescent material light may be re-converted by the third luminescent material into the first (far-red) part of the third luminescent material light. Hence, in embodiments, the dichroic mirrors may comprise a fourth dichroic beam splitter having a fourth cut-off wavelength ( c4), wherein the fourth cut-off wavelength ( c4) may be selected from the range of 650-660 nm; wherein the fourth dichroic beam splitter may be configured in a light-receiving relationship with the third luminescent material, and wherein the third dichroic beam splitter may be configured in a light-receiving relationship with the fourth dichroic beam splitter; wherein the fourth dichroic beam splitter may be configured (i) to transmit a first part of the third luminescent material light having a wavelength selected from <Zc4 and to reflect a second part of the third luminescent material light having a wavelength selected from >><4, or (ii) to reflect a first part of the third luminescent material light having a wavelength selected from <Xc4 and to transmit a second part of the third luminescent material light having a wavelength selected from >Xc4; and wherein the fourth dichroic beam splitter may be configured to provide the second part of the third luminescent material light back to the third luminescent material.

[0071] Such embodiments may be beneficial as the contribution of the first part of third luminescent material light (having the desired optimal wavelength range) relative to the contribution of the second part of third luminescent material light (having the less desired or less optimal wavelength range) may be increased, therewith improving the (far-)red contribution to the spectral power distribution of the system light.

[0072] The light generating system comprises, as described above, components such as luminescent materials and a diffuser. Such components may, in embodiments, be (individually) operated in the reflective mode and / or in the transmissive mode, see also further above. Herein, in embodiments, one or more of the diffuser, the first luminescent material, the second luminescent material, (and optionally the third luminescent material) may especially be configured in the reflective mode.

[0073] In embodiments where a luminescent material is configured in the reflective mode it may be advantageous to configure the luminescent material on a rotating element, such as e.g. a phosphor wheel, a phosphor disc or a rotating rod. The luminescent material may especially be comprised by a luminescent body. The luminescent body may be a layer, like a self-supporting layer. The luminescent body may also be a coating. The luminescent body may also comprise a luminescent coating on a support (especially a light transmissive support in the transmissive mode). Especially, the luminescent body may essentially be self- supporting. In embodiments, the luminescent material may be provided as luminescent body, such as a luminescent single crystal, a luminescent glass, or a luminescent ceramic body. Such body may be indicated as “converter body” or “luminescent body”. For instance, in embodiments a cerium comprising garnet luminescent material may be provided as a luminescent single crystal or as a luminescent ceramic body. In other embodiments, the luminescent body may comprise a light transmissive body, wherein the luminescent material is embedded. For instance, the luminescent body may comprise a glass body, with luminescent material embedded therein. Or, the glass as such may be luminescent. In other embodiments, the luminescent body may comprise a polymeric body, with luminescent material embedded therein. In specific embodiments, the luminescent body comprises a ceramic body comprising the luminescent material. Ceramic bodies are known in the art. Alternatively, the luminescent body comprises single crystal. In yet further specific embodiments, different types of luminescent bodies may be applied. Hence, the body may especially be selected from single crystalline bodies and ceramic bodies.

[0074] In embodiments, the luminescent body (or “body”) may have lateral dimensions width or length (W or L) or diameter (D) and a thickness or height (H). In embodiments, (i) D>H or (ii) and W>H and / or L>H. In specific embodiments, L, D, W, and H may be individually selected from the range of <10 mm, such as especially from the range of <5mm, more especially from the range of <3 mm, most especially from the range of <2 mm. Especially, the lateral dimensions like length, width, and diameter are at least 2 times, like at least 5 times, larger than the height.

[0075] The luminescent body may have any shape. In general, however, the luminescent body may comprise two essentially parallel faces, defining a height (of the luminescent body). Further, the luminescent body may comprise an edge face, bridging the two essentially parallel faces. The edge face may be curved in one or two dimensions. The edge face may be planar. The two essentially parallel faces may also be indicated as “main faces”, as they may especially provide the largest external area of the luminescent body. In embodiments, the luminescent body may e.g. have a cubic shape, a (non-cubic) cuboid shape, an n-gonal prism shape with n being at least 5 (such as pentagonal prism, hexagonal prism), and a cylindrical shape. Other shapes, however, may also be possible. Especially, the luminescent body may have a cuboid shape, a cylindrical shape, or a (regular) n-gonal prism shape wherein n is 6 or 8. In the case of a cylindrical shape, the edge face may be a single edge face. In the case of a cuboid, the edge face may comprise four facets. In the case of a hexagonal prism the edge face may comprise six facets.

[0076] Further, in embodiments, when the diffuser may be configured in the reflective mode, the first device light may comprise linearly polarized light, such as e.g. p-polarized light and / or s-polarized light. Additionally, in such embodiments, the beam combiner may comprise a polarizing beam splitter. The polarizing beam splitter may, in embodiments, be configured (i) to reflect one of first linearly polarized light and second linearly polarized light received by the polarizing beam splitter and (ii) to transmit the other one of first linearly polarized light and second linearly polarized light received by the polarizing beam splitter. Yet additionally, in such embodiments, the light generating system may comprise a X / 4 waveplate configured between the beam combiner and the diffuser. The 4 waveplate may, in embodiments, be configured (i) to convert first linearly polarized light received by the X / 4 waveplate into first circularly polarized light and (ii) to convert second circularly polarized light received by the X / 4 waveplate into second linearly polarized light. Yet additionally, in such embodiments, the diffuser may comprise a polarization maintaining diffuser. As such, a typical propagation of light via the diffuser to the beam combiner may be as follows: (i) first linearly polarized device light (from the first light generating device) may be provided to the X / 4 waveplate, (ii) the X / 4 waveplate may convert the first linearly polarized device light into first circularly polarized light and provide it to the diffuser, (iii) the first circularly polarized light may be diffused and reflected by the (polarization maintaining) diffuser such that diffused second circularly polarized light may propagate back to the X / 4 waveplate, (iv) the X / 4 waveplate may convert the diffused second circularly polarized light into diffused second linearly polarized device light, and (v) the polarizing beam splitter (comprised by the beam combiner) may combine the diffused second linearly polarized device light with the one or more types of luminescent material light.

[0077] In specific embodiments, (all of) the diffuser, the first luminescent material, the second luminescent material, (and optionally the third luminescent material) may be configured in the reflective mode.

[0078] Referring back to the light generating devices, as indicated above, the light generating system comprises a light generating device comprising a light source and may especially be configured to generate device light. In embodiments, the device light may essentially consist of the device light. In other embodiments, the device light may essentially consist of converted light source light. In yet other embodiments, the device light may comprise (unconverted) light source light and converted light source light. Light source light may be converted with a luminescent material into luminescent material light and / or with an upconverter into upconverted light (see also below). The term “light generating device” may also refer to a plurality of light generating devices which may provide device light having essentially the same spectral power distributions. In specific embodiments, the term “light generating device” may also refer to a plurality of light generating devices which may provide device light having different spectral power distributions.

[0079] The term “light source” may in principle relate to any light source known in the art. In a specific embodiment, the light source comprises a solid state LED light source (such as an LED or laser diode (or “diode laser”)). The term “light source” may also relate to a plurality of (essentially identical (or different)) light sources, such as 2-2000 solid state light sources. The light source may have a light escape surface. For LED’s it may for instance be the LED die, or when a resin is applied to the LED die, the outer surface of the resin. In principle, it may also be the terminal end of a fiber. The term escape surface especially relates to that part of the light source, where the light actually leaves or escapes from the light source. The light source is configured to provide a beam of light. This beam of light (thus) escapes from the light exit surface of the light source. Likewise, a light generating device may comprise a light escape surface, such as an end window. Further, likewise a light generating system may comprise a light escape surface, such as an end window.

[0080] A position where system light escapes from the light generating system may also be indicated as light exit. This may be a light transmissive window or an opening (in the system). The light transmissive window may in embodiments be provided by an optical component.

[0081] The term “light source” may refer to a semiconductor light-emitting device, such as a light emitting diode (LEDs), a resonant cavity light emitting diode (RCLED), a vertical cavity laser diode (VCSELs), an edge emitting laser, etc... The terms “light source” or “solid state light source” may also refer to a superluminescent diode (SLED).

[0082] In embodiments, the light source may be configured to provide primary radiation, which is used as such, such as e.g. a blue light source, like a blue LED, or a green light source, such as a green LED, and a red light source, such as a red LED. Such LEDs, which may not comprise a luminescent material (“phosphor”) may be indicated as direct color LEDs.

[0083] In embodiments, the light generating device may comprise a luminescent material. In embodiments, the light generating device may comprise a PC LED. In other embodiments, the light generating device may comprise a direct LED (i.e. no phosphor). In embodiments, the light generating device may comprise a laser device, like a laser diode. In embodiments, the light generating device may comprise a superluminescent diode. Hence, in specific embodiments, the light source may be selected from the group of laser diodes and superluminescent diodes. In other embodiments, the light source may comprise an LED.

[0084] The light source may especially be configured to generate light source light having an optical axis (O), (a beam shape,) and a spectral power distribution. The light source light may in embodiments comprise one or more bands, e.g. having band widths as known for lasers.

[0085] The term “light source” may (thus) refer to a light generating element as such, like e.g. a solid state light source, or e.g. to a package of the light generating element, such as a solid state light source, and one or more of a luminescent material comprising element and (other) optics, like a lens, a collimator. A light converter element (“converter element” or “converter”) may comprise a luminescent material comprising element. For instance, a solid state light source as such, like a blue LED, is a light source. A combination of a solid state light source (as light generating element) and a light converter element, such as a blue LED and a light converter element, optically coupled to the solid state light source, may also be a light source (but may also be indicated as light generating device). Hence, a white LED is a light source (but may e.g. also be indicated as (white) light generating device). The term “light source” may (thus) in embodiments also refer to a light source that is (also) based on conversion of light, such as a light source in combination with a luminescent converter material.

[0086] The terms “light source”, “solid state light source”, or “solid state material light source”, and similar terms, herein may especially refer to a semiconductor light source comprising a solid state light source, such as an LED or a laser diode or a superluminescent diode.

[0087] In embodiments, the term “light source” may also refer to a combination of a light source, like an LED, and an optical filter, which may change the spectral power distribution of the light generated by the light source. Especially, the term “light generating device” may be used to address a light source and further (optical components), like an optical filter and / or a beam shaping element, etc.

[0088] The phrases “different light sources” or “a plurality of different light sources”, and similar phrases, may in embodiments refer to a plurality of solid-state light sources selected from at least two different bins. Likewise, the phrases “identical light sources” or “a plurality of same light sources”, and similar phrases, may in embodiments refer to a plurality of solid-state light sources selected from the same bin.

[0089] The term “laser light source” especially refers to a laser. Such laser may especially be configured to generate laser light source light having one or more wavelengths in the UV, visible, or infrared, especially having a wavelength selected from the spectral wavelength range of 200-2000 nm, such as 300-1500 nm. The term “laser” especially refers to a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. Especially, in embodiments the term “laser” may refer to a solid-state laser. In specific embodiments, the terms “laser” or “laser light source”, or similar terms, refer to a laser diode (or diode laser). Hence, in embodiments the light source comprises a laser light source. In embodiments, the terms “laser” or “solid state laser” or “solid state material laser” may refer to one or more of cerium doped lithium strontium (or calcium) aluminum fluoride (Ce:LiSAF, Ce:LiCAF), chromium doped chrysoberyl (alexandrite) laser, chromium ZnSe (Cr:ZnSe) laser, divalent samarium doped calcium fluoride (Sm:CaF2) laser, Er: YAG laser, erbium doped and erbium-ytterbium codoped glass lasers, F-Center laser, holmium YAG (Ho:YAG) laser, Nd:YAG laser, NdCrYAG laser, neodymium doped yttrium calcium oxoborate Nd: YCa4O(BO3)3 or Nd:YCOB, neodymium doped yttrium orthovanadate (Nd:YVO4) laser, neodymium glass (Nd:glass) laser, neodymium YLF (Nd:YLF) solid-state laser, promethium 147 doped phosphate glass (147Pm3+:glass) solid-state laser, ruby laser (AhO3:Cr3+), thulium YAG (Tm:YAG) laser, titanium sapphire (Ti:sapphire; AhO3:Ti3+) laser, trivalent uranium doped calcium fluoride (U:CaF2) solid-state laser, Ytterbium doped glass laser (rod, plate / chip, and fiber), Ytterbium YAG (Yb:YAG) laser, Yb2O3 (glass or ceramics) laser, etc.

[0090] For instance, including second and third harmonic generation embodiments, the light source may comprise one or more of an F center laser, an yttrium orthovanadate (Nd:YVO4) laser, a promethium 147 doped phosphate glass (147Pm3+:glass), and a titanium sapphire (Ti:sapphire; AhO3:Ti3+) laser. For instance, considering second and third harmonic generation, such light sources may be used to generated blue light.

[0091] In embodiments, the terms “laser” or “solid state laser” or “solid state material laser” may refer to one or more of a semiconductor laser diodes, such as GaN, InGaN, AlGalnP, AlGaAs, InGaAsP, lead salt, vertical cavity surface emitting laser (VCSEL), quantum cascade laser, hybrid silicon laser, etc.

[0092] As can be derived from the below, the term “laser light source” may also refer to a plurality of (different or identical) laser light sources. In specific embodiments, the term “laser light source” may refer to a plurality N of (identical) laser light sources. In embodiments, N=2, or more. In specific embodiments, N may be at least 5, such as especially at least 8. In this way, a higher brightness may be obtained. In embodiments, laser light sources may be arranged in a laser bank (see also above). The laser bank may in embodiments comprise heat sinking and / or optics e.g. a lens to collimate the laser light. Hence, in embodiments lasers in a laser bank (or “laser array bank”) may share the same optics.

[0093] The laser light source is configured to generate laser light source light (or

[0094] “laser light”). The light source light may essentially consist of the laser light source light. The light source light may also comprise laser light source light of two or more (different or identical) laser light sources. In specific embodiments, the light source light is especially (collimated) laser light source light.

[0095] The laser light source light may in embodiments comprise one or more bands, having band widths as known for lasers. In specific embodiments, the band(s) may be relatively sharp line(s), such as having full width half maximum (FWHM) in the range of less than 20 nm at RT, such as equal to or less than 10 nm. Hence, the light source light has a spectral power distribution (intensity on an energy scale as function of the wavelength) which may comprise one or more (narrow) bands.

[0096] The beams (of light source light) may be focused or collimated beams of (laser) light source light. The term “focused” may especially refer to converging to a small spot. This small spot may be at the discrete converter region, or (slightly) upstream thereof or (slightly) downstream thereof. Especially, focusing and / or collimation may be such that the cross-sectional shape (perpendicular to the optical axis) of the beam at the discrete converter region (at the side face) is essentially not larger than the cross-section shape (perpendicular to the optical axis) of the discrete converter region (where the light source light irradiates the discrete converter region). Focusing may be executed with one or more optics, like (focusing) lenses. Especially, two lenses may be applied to focus the laser light source light. Collimation may be executed with one or more (other) optics, like collimation elements, such as lenses and / or parabolic mirrors. In embodiments, the beam of (laser) light source light may be relatively highly collimated, such as in embodiments <2° (FWHM), more especially <1° (FWHM), most especially <0.5° (FWHM). Hence, <2° (FWHM) may be considered (highly) collimated light source light. Optics may be used to provide (high) collimation (see also above).

[0097] The term “solid state material laser”, and similar terms, may refer to a solid state laser like based on a crystalline or glass body doped with ions, like transition metal ions and / or lanthanide ions, to a fiber laser, to a photonic crystal laser, to a semiconductor laser, such as e.g. a vertical cavity surface-emitting laser (VCSEL), etc.

[0098] A light-emitting diode (LED) is especially a semiconductor light source that emits light when current flows through it. Electrons in the semiconductor may recombine with electron holes, releasing energy in the form of photons. The color of the light (corresponding to the energy of the photons) may be determined by the energy required for electrons to cross the band gap of the semiconductor. Superluminescent diodes are known in the art. A superluminescent diode may be indicated as a semiconductor device which may be able to emit low-coherence light of a broad spectrum like an LED, while having a brightness in the order of a laser diode. Superluminescent diodes may combine the high power and brightness of laser diodes with the low coherence of conventional light-emitting diodes. The low (temporal) coherence of the source has advantages that the speckle is significantly reduced or not visible, and the spectral distribution of emission is much broader compared to laser diodes, which can be better suited for lighting applications. For instance, in further specific embodiments, the solid state light source may comprise a GaN-based superluminescent diode, or an InGaN-based superluminescent diode, or an AlGaN-based superluminescent diode.

[0099] The light generating system may be part of or may be applied in e.g. office lighting systems, household application systems, shop lighting systems, home lighting systems, accent lighting systems, spot lighting systems, theater lighting systems, fiber-optics application systems, projection systems, self-lit display systems, pixelated display systems, segmented display systems, warning sign systems, medical lighting application systems, indicator sign systems, decorative lighting systems, portable systems, automotive applications, (outdoor) road lighting systems, urban lighting systems, green house lighting systems, horticulture lighting, digital projection, or LCD backlighting. The light generating system (or luminaire) may be part of or may be applied in e.g. optical communication systems or disinfection systems.

[0100] The terms “visible”, “visible light” or “visible emission” and similar terms refer to light having one or more wavelengths in the range of about 380-780 nm. Herein, UV may especially refer to a wavelength selected from the range of 190-380 nm, such as 200-380 nm. Herein, IR (infrared) may especially refer to radiation having a wavelength selected from the range of 780-3000 nm, such as 780-2000 nm, e.g. a wavelength up to about 1500 nm, like a wavelength of at least 900 nm, though in specific embodiments other wavelengths may also be possible.

[0101] The terms “light” and “radiation” are herein interchangeably used, unless clear from the context that the term “light” only refers to visible light. The terms “light” and “radiation” may thus refer to UV radiation, visible light, and IR radiation. In specific embodiments, especially for lighting applications, the terms “light” and “radiation” refer to (at least) visible light.

[0102] The terms “blue light” or “blue emission” especially relates to light having a wavelength in the range of about 440-495 nm (including some violet and cyan hues). The terms “green light” or “green emission” especially relate to light having a wavelength in the range of about 495-570 nm. The terms “yellow light” or “yellow emission” especially relate to light having a wavelength in the range of about 570-590 nm. The terms “orange light” or “orange emission” especially relate to light having a wavelength in the range of about 590- 620 nm. The terms “red light” or “red emission” especially relate to light having a wavelength in the range of about 620-780 nm. The phrase “light having one or more wavelengths in a wavelength range” and similar phrases may especially indicate that the indicated light (or radiation) has a spectral power distribution with at least intensity or intensities at these one or more wavelengths in the indicate wavelength range. For instance, a blue emitting solid state light source will have a spectral power distribution with intensities at one or more wavelengths in the 440-495 nm wavelength range.

[0103] The light generating system may further comprise a control system. The control system may, in embodiments, be configured to control the spectral power distribution (and radiant flux) of the system light. Additionally or alternatively, in embodiments, the control system may be configured to control the correlated color temperature (CCT) of the system light. Additionally or alternatively, in embodiments, the control system may be configured to control the color rendering index (CRI) of the system light. The control system may do so by controlling one or more of the light generating devices comprised by the light generating system. Especially, in embodiments, the control system may be configured to control one or more of the first light generating device, the second light generating device, and the third light generating device. In some embodiments, the control system may especially be configured to individually control two or more of the first light generating device, the second light generating device, and the third light generating device. The system may be configured to control one or more of the first light generating device, the second light generating device, and the third light generating device, such that in a first operational mode the system light may have a first correlated color temperature (CCT1). Additionally or alternatively, in embodiments, the control system may be configured to control one or more of the first light generating device, the second light generating device, and the third light generating device, such that in a second operational mode the system light may have a second correlated color temperature (CCT2). Especially, in embodiment, the control system may be configured to individually control the light generating devices, such that the CCT may be altered from CCT1 in the first operational mode to CCT2 in the second operational mode, and vice versa. Further, in embodiments, CCT2-CCTl>250 K, like CCT2-CCTl>500 K, such as CCT2-CCTl>750 K, like, CCT2-CCTl>1000 K, especially CCT2-CCTl>1500 K. In embodiments, CCT2-CCT1 may be at most 5000K, such as at most 3000K, like at most 2500K. Hence, in embodiments, the light generating system may comprise a control system, wherein the control system may be configured to control one or more of the spectral power distribution, the correlated color temperature, and the color rendering index of the system light, wherein the control system may be configured to (individually) control (one or more of) the first light generating device, the second light generating device, and the third light generating device, such that: (i) in a first operational mode the system light has a first correlated color temperature (CCT1), and (ii) in a second operational mode the system light has a second correlated color temperature (CCT2); and wherein CCT2-CCTl>500K.

[0104] The term “controlling” and similar terms especially refer at least to determining the behavior or supervising the running of an element. Hence, herein “controlling” and similar terms may e.g. refer to imposing behavior to the element (determining the behavior or supervising the running of an element), etc., such as e.g. measuring, displaying, actuating, opening, shifting, changing temperature, etc.. Beyond that, the term “controlling” and similar terms may additionally include monitoring. Hence, the term “controlling” and similar terms may include imposing behavior on an element and also imposing behavior on an element and monitoring the element. The controlling of the element can be done with a control system, which may also be indicated as “controller”. The control system and the element may thus at least temporarily, or permanently, functionally be coupled. The element may comprise the control system. In embodiments, the control system and element may not be physically coupled. Control can be done via wired and / or wireless control. The term “control system” may also refer to a plurality of different control systems, which especially are functionally coupled, and of which e.g. one control system may be a master control system and one or more others may be slave control systems. A control system may comprise or may be functionally coupled to a user interface.

[0105] The control system may also be configured to receive and execute instructions from a remote control. In embodiments, the control system may be controlled via an App on a device, such as a portable device, like a Smartphone or I-phone, a tablet, etc.. The device is thus not necessarily coupled to the lighting system, but may be (temporarily) functionally coupled to the lighting system.

[0106] Hence, in embodiments the control system may (also) be 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 control in a slave mode. For instance, the lighting system may be identifiable with a code, especially a unique code for the respective lighting system. The control system of the lighting system may be configured to be controlled by an external control system which has access to the lighting system on the basis of knowledge (input by a user interface of with an optical sensor (e.g. QR code reader) of the (unique) code. The lighting system may also comprise means for communicating with other systems or devices, such as on the basis of Bluetooth, Thread, WIFI, LiFi, ZigBee, BLE or WiMAX, or another wireless technology.

[0107] The system, or apparatus, or device may execute an action in a “mode” or “operation mode” or “mode of operation” or “operational mode”. The term “operational mode may also be indicated as “controlling mode”. Likewise, in a method an action or stage, or step may be executed 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 also be adapted for providing another controlling mode, or a plurality of other controlling modes. Likewise, this may not exclude that before executing the mode and / or after executing the mode one or more other modes may be executed.

[0108] However, in embodiments a control system may be available, that is adapted to provide at least the controlling mode. Would other modes be available, the choice of such modes may especially be executed via a user interface, though other options, like executing a mode in dependence of a sensor signal or a (time) scheme, may also be possible. The operation mode may in embodiments also refer to a system, or apparatus, or device, that can only operate in a single operation mode (i.e. “on”, without further tunability).

[0109] Hence, in embodiments, the control system may control in dependence of one or more of an input signal of a user interface, a sensor signal (of a sensor), and a timer. The term “timer” may refer to a clock and / or a predetermined time scheme. Especially, in embodiments, the control system may be configured to control the spectral power distribution of the system light in dependence of one or more of an input signal of a user interface, a sensor signal (of a sensor), and a timer. For example, in embodiments, a sensor may be configured functionally (such as communicatively) coupled with the control system.

[0110] In yet a further aspect, the invention also provides a lamp or a luminaire comprising the light generating system as defined herein. The luminaire may further comprise a housing, optical elements, louvres, etc. The lamp or luminaire may further comprise a housing enclosing the light generating system. The lamp or luminaire may comprise a light window in the housing or a housing opening, through which the system light may escape from the housing. In yet a further aspect, the invention also provides a projection device comprising the light generating system as defined herein. Especially, a projection device or “projector” or “image projector” may be an optical device that projects an image (or moving images) onto a surface, such as e.g. a projection screen. The projection device may include one or more light generating systems such as described herein. Hence, in an aspect the invention also provides a lighting 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 the light generating system as defined herein. The lighting device may comprise a housing or a carrier, configured to house or support, one or more elements of the light generating system. For instance, in embodiments the lighting device may comprise a housing or a carrier, configured to house or support one or more of the light generating devices, the (first, second, and optionally third) luminescent materials, the dichroic mirrors, the beam combiner, the diffuser and the control system.

[0111] Instead of the terms “lighting device” or “lighting system”, and similar terms, also the terms “light generating device” or “light generating system”, (and similar terms), may be applied. A lighting device or a lighting system may be configured to generate device light (or “lighting device light”) or system light (“or lighting system light”). As indicated above, the terms light and radiation may interchangeably be used.

[0112] The lighting device may comprise a light source. The device light may in embodiments comprise one or more of light source light and converted light source light (such as luminescent material light). The lighting system may comprise a light source. The system light may in embodiments comprise one or more of light source light and converted light source light (such as luminescent material light).

[0113] BRIEF DESCRIPTION OF THE DRAWINGS

[0114] Embodiments of the 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:

[0115] Fig. 1, 2, 3A-B, and 4 schematically depict some embodiments of the light generating system.

[0116] Fig. 5 schematically depicts some applications of the light generating system in lighting devices.

[0117] The schematic drawings are not necessarily to scale.

[0118] DETAILED DESCRIPTION OF THE EMBODIMENTS Fig. 1 schematically depicts a light generating system 1000 configured to provide system light 1001. As depicted, the light generating system 1000 may comprise light generating devices 100 configured to generate device light 101, luminescent materials 200, dichroic mirrors 400, a beam combiner 500, and a diffuser 710.

[0119] In embodiments, the light generating devices 100 may comprise a first light generating device 110 configured to generate first device light 111. Especially, in embodiments, the first light generating device 110 may comprise a first laser bank comprising a plurality of first lasers 10 configured to generate first light source light 11. Further, in embodiments, the light generating devices 100 may comprise a second light generating device 120 configured to generate second device light 121. Especially, the second light generating device 120 may comprise a second laser bank comprising a plurality of second lasers 20 configured to generate second light source light 21. Further, in embodiments, the light generating devices 100 may comprise a third light generating device 130 configured to generate third device light 131. Especially, the third light generating device 130 may comprise a third laser bank comprising a plurality of third lasers 30 configured to generate third light source light 31.

[0120] Moreover, in embodiments, the diffuser 710 may be configured in a lightreceiving relationship with the first light generating device 110 and may be configured to diffuse (at least part of) first device light 111 received by the diffuser 710 into diffused first device light 711.

[0121] The luminescent materials 200 may, in embodiments, comprise a first luminescent material 210, a second luminescent material 220, and optionally a third luminescent material 230 (see Figs. 3A-B). Especially, in embodiments, the light generating system may comprise a first luminescent element 1200 comprising the first luminescent material 210, a second luminescent element 2200 comprising the second luminescent material 220, and optionally a third luminescent element 3200 comprising the third luminescent material 230. The luminescent materials 200 may especially be configured to convert light received by the luminescent material 200 into luminescent material light 201.

[0122] Especially, in embodiments, the first luminescent material 210 may be configured in a light-receiving relationship with the second light generating device 120. The first luminescent material 210 may especially be configured to (at least part of) convert second device light 121 received by the first luminescent material 210 into first luminescent material light 211 having a first peak emission wavelength ( i) selected from the wavelength range of 500-540 nm. Similarly, in embodiments, the second luminescent material 220 may be configured in a light-receiving relationship with the third light generating device 130. The second luminescent material 220 may especially be configured to convert (at least part of) the third device light 131 received by the second luminescent material 220 into second luminescent material light 221 having a second peak emission wavelength ( ) selected from the wavelength range of 540-590 nm.

[0123] As depicted, in embodiments, the dichroic mirrors 400 may comprise a first dichroic beam splitter 410 and a second dichroic beam splitter 420. In embodiments, the first dichroic beam splitter 410 may have a first cut-off wavelength ( ci). In specific embodiments, the first cut-off wavelength ( ci) may be selected from the range of 560-580 nm.

[0124] In embodiments, the first dichroic beam splitter 410 may be configured in a light-receiving relationship with the first luminescent material 210. In embodiments, the first dichroic beam splitter 410 may especially be configured (i) to transmit (as depicted here) or reflect (not depicted) (at least part of) a first part of the first luminescent material light 211a having a wavelength selected from the range of <> i and (ii) to reflect (as depicted here) or transmit (not depicted) (at least part of)a second part of the first luminescent material light 211b having a wavelength selected from the range of > ci.

[0125] In some embodiments, the light generating system 1000 may comprise a beam dump 600. Especially, in such embodiments, the first dichroic beam splitter 410 may be configured to provide (at least part of) the second part of the first luminescent material light 21 lb to the beam dump 600. However, this may not necessarily be the case, see e.g. Figs. 2- 4. Reference 570 may herein refer to optics, especially to a (condensing) lens.

[0126] Similarly, in embodiments, the second dichroic beam splitter 420 may have a second cut-off wavelength ( ci). Especially, ci ci. Moreover, in specific embodiments, the second cut-off wavelength ( ci) may be selected from the range of 565-585 nm.

[0127] In embodiments, the second dichroic beam splitter 420 may be configured in a light-receiving relationship with the second luminescent material 220. In embodiments, the second dichroic beam splitter 420 may especially be configured (i) to transmit (as depicted here) or reflect (not depicted) (at least part of) a first part of the second luminescent material light 221a having a wavelength selected from the range of <><2 and (ii) to reflect (as depicted here) or transmit (not depicted) (at least part of) a second part of the second luminescent material light 221b having a wavelength selected from the range of >Xc2. Furthermore, in embodiments, the second dichroic beam splitter 420 may be configured to provide (at least part of) the second part of the second luminescent material light 221b (via one or more lenses 570) back to the second luminescent material 220.

[0128] The beam combiner 500 may, in embodiments, be configured in a lightreceiving relationship with the diffuser 710, the first dichroic beam splitter 410, and the second dichroic beam splitter 420. Hence, in embodiments, the beam combiner 500 may be configured to combine (one or more of) the diffused first device light 711, the first part of the first luminescent material light 211a, and the second part of the second luminescent material light 221a received by the beam combiner 500 into a beam of system light 1001.

[0129] Moreover, in embodiments, in an operational mode of the light generating system 1000 the system light 1001 may be white light having a correlated color temperature in a range from 2000-9000 K and a CRI of at least 70.

[0130] In yet further embodiments, the light generating system 1000 may further comprise a control system 300. In embodiments, the control system 300 may be configured to control one or more of the spectral power distribution, the correlated color temperature, and the color rendering index of the system light 1001. Especially, in embodiments, the control system 300 may be configured to (individually) control (one or more of) the first light generating device 110, the second light generating device 120, and the third light generating device 130.

[0131] Fig. 2 schematically depicts the light generating system 1000, without a beam dump 600. Here, in embodiments, the light generating system 1000 may (instead) comprise one or more optical elements 550, such as e.g. reflectors and / or light guides. In such embodiments, the first dichroic beam splitter 410 may be configured to provide (at least part of) the second part of the first luminescent material light 21 lb to the one or more optical elements 550. Subsequently, in embodiments, the one or more optical elements 550 may be configured to guide (at least part of) the second part of the first luminescent material light 21 lb to the second luminescent material 220. In such embodiments, the second luminescent material 220 may be configured to convert (at least part of) the second part of the first luminescent material light 211b received by the second luminescent material 220 into second luminescent material light 221. Note that, in embodiments, the optical elements 550 may (also) be configured to guide light to one or more other elements. For example, as depicted in Fig. 3B, an optical element 550 may be configured to guide third luminescent material light 231 to the third dichroic beam splitter 430 (see also below), whereas another optical element 550 may be configured to guide first luminescent material light 211 (here via a fifth dichroic beam splitter 450) to the third dichroic beam splitter 430.

[0132] Figs. 3 schematically depict embodiments of the light generating system 1000 wherein the luminescent materials 200 may comprise a third luminescent material 230. Furthermore, as depicted here, the dichroic mirrors 400 may comprise a third dichroic beam splitter 430 having a third cut-off wavelength ( cs). Especially, in embodiments, the third cut-off wavelength ( cs) may be selected from the range of 650-700 nm.

[0133] In embodiments such as depicted in Fig. 3B, the third luminescent material

[0134] 230 may be configured in a light-receiving relationship with the first dichroic beam splitter 410 (, and optionally the second dichroic beam splitter 420, see Fig. 3B). The third luminescent material 230 may especially be configured to convert (at least part of) light received by the third luminescent material 230 into third luminescent material light 231. Furthermore, in embodiments, the third dichroic beam splitter 430 may be configured in a light-receiving relationship with the third luminescent material 230. As such, in embodiments, the third dichroic beam splitter 430 may be configured (i) to reflect (as depicted here) or transmit (not depicted) (at least part of) the third luminescent material light

[0135] 231 and (ii) to transmit (as depicted here) or reflect (not depicted) (one or more of) the diffused first device light 711, the first luminescent material light 211 and the second luminescent material light 221.

[0136] Furthermore, in embodiments, the beam combiner 500 may be configured in a light-receiving relationship with the third dichroic beam splitter 430. The beam combiner 500 may, in embodiments, especially be configured such that in an operational mode of the light generating system 1000 the system light 1001 may further comprise (at least part of) the third luminescent material light 231.

[0137] Herein, reference 580 may refer to optics, especially to integrators.

[0138] As depicted in Fig. 3 A, in embodiments, the light generating system 1000 may comprise one or more optical elements 550, such as e.g. reflectors. Here, the third luminescent material light 231 may comprise a first part of third luminescent material light 231a having a wavelength selected from the range of <Xc3, and a second part of third luminescent material light 23 lb having a wavelength selected from the range of >Xc3. In such embodiments, the first dichroic beam splitter 410 may be configured to provide (at least part of) the second part of the first luminescent material light 21 lb to the one or more optical elements 550. Subsequently, in embodiments, the one or more optical elements 550 may be configured to guide (at least part of) the second part of the first luminescent material light 211b to the third luminescent material 230. In embodiments, the third luminescent material 230 may be configured to convert (at least part of) the second part of the first luminescent material light 211b received by the third luminescent material 230 into third luminescent material light 231.

[0139] Fig. 3 A further schematically depicts an embodiment where the light generating system 1000 comprises a fourth dichroic beam splitter 440. The fourth dichroic beam splitter 440 may have a fourth cut-off wavelength ( c4). In embodiments, the fourth cut-off wavelength ( c4) may be selected from the range of 650-660 nm. The fourth dichroic beam splitter 440 may, in embodiments, be configured in a light-receiving relationship with the third luminescent material 230. Further, in embodiments, the third dichroic beam splitter 430 may be configured in a light-receiving relationship with the fourth dichroic beam splitter 440. In embodiments, the fourth dichroic beam splitter 440 may especially be configured (i) to transmit (as depicted here) or reflect (not depicted) a first part of the third luminescent material light 231a having a wavelength selected from <Xc4 and (ii) to reflect (as depicted here) or transmit (not depicted) a second part of the third luminescent material light 23 lb having a wavelength selected from >Xc4. Moreover, in embodiments, the fourth dichroic beam splitter 440 may be configured to provide the second part of the third luminescent material light 23 lb back to the third luminescent material 230.

[0140] In the aforementioned figures the diffuser 710, the first luminescent material 210, the second luminescent material 220, and even the third luminescent material 230 are all configured in the transmissive mode. However, this may not always be the case. For example, as depicted in Fig. 3B, the diffuser 710 may be configured in the reflective mode. In such embodiments, when the diffuser 710 may be configured in the reflective mode, the first device light 111 may especially comprise linearly polarized light. Therefore, in such embodiments, the beam combiner 500 may comprise a polarizing beam splitter 505. Especially, in embodiments, the polarizing beam splitter 505 may be configured (i) to reflect one of first linearly polarized light and second linearly polarized light received by the polarizing beam splitter 505 and (ii) to transmit the other one of first linearly polarized light and second linearly polarized light received by the polarizing beam splitter 505. Furthermore, in embodiments when the diffuser 710 may be configured in the reflective mode, the light generating system 1000 may further comprise a X / 4 waveplate 720 configured between the beam combiner 500 and the diffuser 710. In embodiments, the X / 4 waveplate 720 may be configured (i) to convert first linearly polarized (device) light into first circularly polarized (device) light, and (ii) to convert second circularly polarized (diffused device) light into second linearly polarized (diffused device) light. Hence, in such embodiments, the diffuser 710 may comprise a polarization maintaining diffuser, such that first circularly polarized device light 111 received by the diffuser 710 may be diffused into second circularly polarized diffused device light 711.

[0141] Yet further, in embodiments, it may be desired to provide a safety element configured to prevent luminescent material light 201 from propagating back to the light generating devices 100. For example, in embodiments as depicted in Fig. 3B, a dichroic green-light reflector 415 may be configured between the first light generating device 110 and the first luminescent material 210. Similarly, in embodiments, as depicted in Fig. 3B, a dichroic red-light reflector 425 may be configured between the second light generating device 120 and the second luminescent material 220. Additionally or alternatively, in embodiments, the safety element may comprise a (metallic) plate comprising a pinhole, such that the (relatively narrow beam of) first and / or second device light 111,121 may pass through, but the (relatively wide beam of) first and / or second luminescent material light 211,221 may be substantially blocked.

[0142] Hence, in embodiments, one or more of the diffuser 710, the first luminescent material 210, the second luminescent material 220, (and optionally the third luminescent material 230) may be configured in the reflective mode.

[0143] In specific embodiments, such as depicted in Fig. 4, all of the diffuser 710, the first luminescent material 210, the second luminescent material 220, (and optionally the third luminescent material 230) may be configured in the reflective mode. In such embodiments, it may be desired to configured the luminescent materials 200 onto (or embedded into) a rotating element 750, such as e.g. a phosphor wheel or a phosphor disc. Furthermore, as depicted in Figs. 3B and 4, in embodiments, the light generating system 1000, especially the dichroic mirrors 400, may comprise a fifth dichroic beam splitter 450. The fifth dichroic beam splitter 450 may, in embodiments, be configured to combine the (first part of the) first luminescent material light 211 and the (first part of the) second luminescent material light 221 into a same optical path towards the third dichroic beam splitter 430 (as depicted in Fig. 3B) or to the beam combiner 500 (as depicted in Fig 4). Therefore, in embodiments, the fifth dichroic beam splitter 450 may be configured (i) to substantially transmit the (first part of the) first luminescent material light 211, and (ii) to substantially reflect the (first part of the) second luminescent material light 221. Alternatively, in embodiments (not depicted), the fifth dichroic beam splitter 450 may be configured (i) to substantially reflect the (first part of the) first luminescent material light 211, and (ii) to substantially transmit the (first part of the) second luminescent material light 221.

[0144] Fig. 5 schematically depicts an embodiment of a luminaire 2 comprising the light generating system 1000 as described above. Reference 301 indicates a user interface which may be functionally coupled with the control system 300 comprised by or functionally coupled to the light generating system 1000. In embodiments, the control system 300 may be configured to control the spectral power distribution of the system light 1001 in dependence of one or more of an input signal of the user interface 301, a sensor signal, and a timer. Fig. 5 also schematically depicts an embodiment of lamp 1 comprising the light generating system 1000. Reference 3 indicates a projector device or projector system, which may be used to project images, such as at a wall, which may also comprise the light generating system 1000. Hence, Fig. 5 schematically depicts embodiments of a lighting device 1200 selected from the group of a lamp 1, a luminaire 2, a projector device 3, a disinfection device, a photochemical reactor, and an optical wireless communication device, comprising the light generating system 1000 as described herein. In embodiments, such lighting device may be a lamp 1, a luminaire 2, a projector device 3, a disinfection device, or an optical wireless communication device. Lighting device light escaping from the lighting device 1200 is indicated with reference 1201. Lighting device light 1201 may essentially consist of system light 1001, and may in specific embodiments thus be system light 1001. Reference 1300 refers to a space, such as a room. Reference 1305 refers to a floor and reference 1310 to a ceiling; reference 1307 refers to a wall.

[0145] The term “plurality” refers to two or more. The terms “substantially” or “essentially” herein, and similar terms, will be understood by the person skilled in the art. The terms “substantially” or “essentially” may also include embodiments with “entirely”, “completely”, “all”, etc. Hence, in embodiments the adjective substantially or essentially may also be removed. Where applicable, the term “substantially” or the term “essentially” may also relate to 90% or higher, such as 95% or higher, especially 99% or higher, even more especially 99.5% or higher, including 100%.

[0146] The term “comprise” also includes embodiments wherein the term “comprises” means “consists of’. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

[0147] The term “and / or” especially relates to one or more of the items mentioned before and after “and / or”. For instance, a phrase “item 1 and / or item 2” and similar phrases may relate to one or more of item 1 and item 2. The term "comprising" may in an embodiment refer to "consisting of but may in another embodiment also refer to "containing at least the defined species and optionally one or more other species".

[0148] Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

[0149] The devices, apparatus, or systems may herein amongst others be described during operation. As will be clear to the person skilled in the art, the invention is not limited to methods of operation, or devices, apparatus, or systems in operation.

[0150] It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

[0151] 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 requires otherwise, throughout the description and the claims, the words “comprise”, “comprising”, and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”.

[0152] The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In a device claim, or an apparatus claim, or a 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 measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. In yet a further aspect, the invention (thus) provides a software product, which, when running on a computer is capable of bringing about (one or more embodiments of) the method as described herein.

[0153] The invention also provides a control system that may control the device, apparatus, or system, or that may execute the herein described method or process. Yet further, the invention also provides a computer program product, when running on a computer which is functionally coupled to or comprised by the device, apparatus, or system, controls one or more controllable elements of such device, apparatus, or system. The invention further applies to a device, apparatus, or system comprising one or more of the characterizing features described in the description and / or shown in the attached drawings. The invention further pertains to a method or process comprising one or more of the characterizing features described in the description and / or shown in the attached drawings.

[0154] The various aspects discussed in this patent can be combined in order to provide additional advantages. Further, the person skilled in the art will understand that embodiments can be combined, and that also more than two embodiments can be combined. Furthermore, some of the features can form the basis for one or more divisional applications.

Claims

CLAIMS:

1. A light generating system (1000) configured to provide system light (1001); the light generating system (1000) comprising light generating devices (100), a first luminescent material (210), a second luminescent material (220), dichroic mirrors (400), a beam combiner (500), and a diffuser (710), wherein: each of the light generating devices (100) comprise a solid-state light source selected from the group comprising a light-emitting diode, a laser diode, and a superluminescent diode; wherein the light generating devices (100) comprise a first light generating device (110) configured to generate first device light (111), a second light generating device (120) configured to generate second device light (121), and a third light generating device (130) configured to generate third device light (131); wherein the first device light (111), the second device light (121), and the third device light (131) each have a centroid wavelength individually selected from the wavelength range of 440-490 nm; the diffuser (710) is configured in a light-receiving relationship with the first light generating device (110) and is configured to diffuse first device light (111) received by the diffuser (710) into diffused first device light (711); the first luminescent material (210) is configured in a light-receiving relationship with the second light generating device (120) and is configured to convert second device light (121) received by the first luminescent material (210) into first luminescent material light (211) having a first peak emission wavelength ( i) selected from the wavelength range of 500-540 nm; the second luminescent material (220) is configured in a light-receiving relationship with the third light generating device (130) and is configured to convert the third device light (131) received by the second luminescent material (220) into second luminescent material light (221) having a second peak emission wavelength ( 2) selected from the wavelength range of 540-590 nm; the dichroic mirrors (400) comprise a first dichroic beam splitter (410) having a first cut-off wavelength ( ci), and a second dichroic beam splitter (420) having a second cut-off wavelength ( ci); wherein ci ci; wherein:- the first dichroic beam splitter (410) is configured in a light-receiving relationship with the first luminescent material (210) and is configured (i) to transmit a first part of the first luminescent material light (211a) having a wavelength selected from the range of <Xci and to reflect a second part of the first luminescent material light (211b) having a wavelength selected from the range of > ci, or (ii) to reflect the first part of the first luminescent material light (211a) having a wavelength selected from the range of <Xci and to transmit the second part of the first luminescent material light (211b) having a wavelength selected from the range of > ci; and- the second dichroic beam splitter (420) is configured in a light-receiving relationship with the second luminescent material (220) and is configured (i) to transmit a first part of the second luminescent material light (221a) having a wavelength selected from the range of <><2 and to reflect a second part of the second luminescent material light (221b) having a wavelength selected from the range of >> 2, or (ii) to reflect the first part of the second luminescent material light (221a) having a wavelength selected from the range of <Xc2 and to transmit the second part of the second luminescent material light (221b) having a wavelength selected from the range of >> 2; wherein the second dichroic beam splitter (420) is configured to provide the second part of the second luminescent material light (221b) back to the second luminescent material (220); the beam combiner (500) is configured in a light-receiving relationship with the diffuser (710), the first dichroic beam splitter (410), and the second dichroic beam splitter (420); wherein the beam combiner (500) is configured to combine the diffused first device light (711), the first part of the first luminescent material light (211a), and the first part of the second luminescent material light (221a) received by the beam combiner (500) into a beam of system light (1001);(i) the light generating system (1000) further comprises a beam dump (600), wherein the first dichroic beam splitter (410) is configured to provide at least 90 % of the second part of the first luminescent material light (211b) to the beam dump (600), or wherein (ii) the light generating system (1000) further comprises one or more optical elements (550), wherein the first dichroic beam splitter (410) is configured to provide the second part of the first luminescent material light (211b) to the one or more optical elements (550), wherein the one or more optical elements (550) are configured to guide the second part of the first luminescent material light (211b) to the second luminescent material (220), and wherein the second luminescent material (220) is configured to convert the second part of the firstluminescent material light (211b) received by the second luminescent material (220) into second luminescent material light (221; and in an operational mode of the light generating system (1000) the system light (1001) is white light having a correlated color temperature selected from the range of 2000- 9000 K and a CRI of at least 70.

2. The light generating system (1000) according to claim 1, wherein the first cutoff wavelength ( ci) is selected from the range of 560-580 nm.

3. The light generating system (1000) according to claim 1, wherein the second cut-off wavelength ( ci) is selected from the range of 565-585 nm.

4. The light generating system (1000) according to any one of the preceding claims, the first luminescent material (210) comprises a luminescent material of the type (¥xiiLuxi2A’xi3Cexi4)3B5Oi2 and wherein the second luminescent material (220) comprises a luminescent material of the type (Y^iLu^A’^Ce^^BsOn, wherein A’ comprises one or more of La, Gd, and Tb, and wherein B comprises one or more of Al, Ga, In and Sc; whereinXu + X12 + X13 +xu = 1; Xu + xn> 0; 0 < X13 < 1; and 0.001 < xi4< 0.1; X21 + X22 + X23 + X24=1; X21 + X22> 0; 0 < X23 < 1; and 0.001 < X24 < 0.1; and xn > X22 and X21 > Xu.

5. The light generating system (1000) according to any one of the preceding claims, wherein the first dichroic beam splitter (410) is configured to provide at least 98 % of the second part of the first luminescent material light (211b) to the beam dump (600).

6. The light generating system (1000) according to any one of the preceding claims, wherein a spectral power distribution of the first luminescent material light overlaps a spectral power distribution of the second luminescent material light for 90 % or less.

7. The light generating system (1000) according to any one of the preceding claims, wherein the light generating system (1000) further comprises a third luminescent material (230); wherein the dichroic mirrors (400) comprise a third dichroic beam splitter (430) having a third cut-off wavelength ( c3), wherein the third cut-off wavelength ( c3) is selected from the range of 650-700 nm; wherein the third luminescent material (230) isconfigured in a light-receiving relationship with the first dichroic beam splitter (410) and is configured to convert light received by the third luminescent material (230) into third luminescent material light (231); and wherein the third dichroic beam splitter (430) is configured in a light-receiving relationship with the third luminescent material (230) and is configured (i) to transmit the third luminescent material light (231) and to reflect the diffused first device light (711), the first luminescent material light (211) and the second luminescent material light (221), or (ii) to reflect the third luminescent material light (231) and to transmit the diffused first device light (711), the first luminescent material light (211) and the second luminescent material light (221); wherein the beam combiner (500) is configured in a lightreceiving relationship with the third dichroic beam splitter (430); wherein in an operational mode of the light generating system (1000) the system light (1001) further comprises the third luminescent material light (231).

8. The light generating system (1000) according to claim 7, wherein the light generating system (1000) comprises one or more optical elements (550), wherein the first dichroic beam splitter (410) is configured to provide the second part of the first luminescent material light (211b) to the one or more optical elements (550), and wherein the one or more optical elements (550) are configured to guide the second part of the first luminescent material light (211b) to the third luminescent material (230); wherein the third luminescent material (230) is configured to convert the second part of the first luminescent material light (211b) received by the third luminescent material (230) into third luminescent material light (231).

9. The light generating system (1000) according to any one of the preceding claims 7-8, wherein the dichroic mirrors (400) comprise a fourth dichroic beam splitter (440) having a fourth cut-off wavelength ( c4), wherein the fourth cut-off wavelength ( c4) is selected from the range of 650-660 nm; wherein the fourth dichroic beam splitter (440) is configured in a light-receiving relationship with the third luminescent material (230), and wherein the third dichroic beam splitter (430) is configured in a light-receiving relationship with the fourth dichroic beam splitter (440); wherein the fourth dichroic beam splitter (440) is configured (i) to transmit a first part of the third luminescent material light (231a) having a wavelength selected from <Xc4 and to reflect a second part of the third luminescent material light (23 lb) having a wavelength selected from >Xc4, or (ii) to reflect a first part of the third luminescent material light (231a) having a wavelength selected from <Xc4 and to transmit asecond part of the third luminescent material light (23 lb) having a wavelength selected from >Xc4; and wherein the fourth dichroic beam splitter (440) is configured to provide the second part of the third luminescent material light (23 lb) back to the third luminescent material (230).

10. The light generating system (1000) according to any one of the preceding claims 7-9, wherein third luminescent material (230) comprises at least a luminescent material of the type of a divalent europium comprising oxynitride luminescent material or a divalent europium comprising nitride luminescent material.

11. The light generating system (1000) according to any one of the preceding claims, wherein the first light generating device (110) comprises a first laser bank comprising a plurality of first lasers (10), wherein the second light generating device (120) comprises a second laser bank comprising a plurality of second lasers (20), and wherein the third light generating device (130) comprises a third laser bank comprising a plurality of third lasers (30).

12. The light generating system (1000) according to any one of the preceding claims, wherein the diffuser (710), the first luminescent material (210), and the second luminescent material (220) are configured in the reflective mode.

13. The light generating system (1000) according to any one of the preceding claims, further comprising a control system (300), wherein the control system (300) is configured to control one or more of the spectral power distribution, the correlated color temperature, and the color rendering index of the system light (1001), wherein the control system (300) is configured to control the first light generating device (110), the second light generating device (120), and the third light generating device (130), such that: (i) in a first operational mode the system light (1001) has a first correlated color temperature (CCT1), and (ii) in a second operational mode the system light (1001) has a second correlated color temperature (CCT2); and wherein CCT2-CCTl>500K.

14. The light generating system (1000) according to claim 13, wherein the control system (300) is configured to control the spectral power distribution of the system light(1001) in dependence of one or more of an input signal of a user interface, a sensor signal, and a timer.

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

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