Laser-phosphor engine architecture comprising a geometric beam combiner

Abstract

The invention provides a light generating system (1000) comprising two or more light generating devices (100), a luminescent material (200), a diffuser assembly (700), optics (500), and a light exit (1090), wherein: (A) the two or more light generating devices (100) comprise (i) a first light generating device (110) configured to generate first device light (111) and (ii) a second light generating device (120) configured to generate second device light (121); wherein the first light generating device (110) comprises a first laser bank (1111), wherein the first laser bank (1111) comprises a first array (1110) comprising a plurality of first lasers (1010); wherein the second light generating device (120) comprises a second laser bank (2222), wherein the second laser bank (2222) comprises a second array (2110) comprising a plurality of second lasers (2010); (B) the optics (500) comprise a first beam combiner (1510) and a second beam combiner (1520); (C) the first beam combiner (1510) is configured to direct first device light (111) and second device light (121) in an optical path to another one of the redirection optical elements (1500); wherein the first beam combiner (1510) comprises a geometric beam combiner (GBC1); (D) the optics (500) are configured to direct in a first operational mode of the light generating system (1000) (i) a part of the device light (101), comprising one or more of first device light (111) and second device light (121), in an optical path to the luminescent material (200) via the first beam combiner (1510) and the other one of the redirection optical elements (1500), and (ii) a part of the device light (101) in an optical path to the diffuser assembly (700); (E) the luminescent material (200) is configured to convert at least part of first device light (111) and at least part of second device light (121) received by the luminescent material (200) into luminescent material light (201); (F) the diffuser assembly (700) comprises a diffuser (710); wherein the diffuser (710) is configured to diffuse at least part of the device light (101) received by the diffuser (710) into diffused device light (711); (G) the second beam combiner (1520) is configured to direct luminescent material light (201) and diffused device light (711) towards the light exit (1090); wherein the second beam combiner (1520) comprises a dichroic beam combiner (DBC); (H) the light generating system (1000) is configured to generate in the first operational mode of the light generating system (1000) white system light (1001) comprising at least part of the diffused device light (701) and at least part of the luminescent material light (201).

Description

[0001] Laser-phosphor engine architecture comprising a geometric beam combiner

[0002] FIELD OF THE INVENTION

[0003] The invention relates to a light generating system. The invention further relates to a lighting device comprising the light generating system.

[0004] BACKGROUND OF THE INVENTION

[0005] Lighting fixtures comprising laser diffusion optics are known in the art. US20160223895A1, for instance, describes a light source apparatus and a projection display apparatus including: a laser light source; and a multiplexing reflection mirror having a first surface on which a partial reflection coating having a predetermined reflectance is formed, and a second surface on which a total reflection coating is formed, the first surface and the second surface being opposite to each other and formed in a parallel flat shape. The multiplexing reflection mirror is disposed so as to incline toward an optical path of an emission light from the laser light source such that the emission light is incident from first surface.

[0006] US2021 / 321066A1 discloses a light source device comprising a first light emitting device including a plurality of first solid-state light emitting elements arranged at a regular interval in a two-dimensional array form, and a second light emitting device including a plurality of second solid-state light emitting elements arranged at a regular interval in a two-dimensional array form. A first light combining plate includes a first region and a second region, the first region transmitting first light beams emitted from the plurality of first solid- state light emitting elements of the first light emitting device, the second region reflecting second light beams emitted from the plurality of second solid-state light emitting elements of the second light emitting device. The beam arrangement of (i) the first light beams transmitted through the first light combining plate and (ii) the second light beams reflected by the first light combining plate forms a closest packed array.

[0007] US2022 / 011659A1 discloses a light source apparatus including light sources emitting first and second polarized light, an optical element transmitting one of the polarized light and reflecting the other, a polarization rotator generating polarization rotated light from the first polarized light, a wavelength convertor converting the second polarized light into wavelength converted light, and a controller. The optical element generates emitted light by combining the wavelength converted light and polarization rotated light. The controller acquires respective deterioration amounts of the light sources, and controls, based on respective changes in light emission amounts from the light sources acquired from the deterioration amounts, the light emission amount from at least one of the light sources for making different respective change amounts of the light emission amounts from the light sources, or changing a ratio between respective light emission amounts from the light sources.

[0008] SUMMARY OF THE INVENTION

[0009] Laser-phosphor systems may allow generation of high brightness light and may therefore be used in projection systems, including displays such as cinema projectors and projectors for home, school, and office applications, car front lighting, search lighting, stage lighting, architectural lighting, and special lighting applications. However, such light engine may be capable to generate only a single color point as defined by the luminescent converter. Creation of a product range providing different color points may be difficult as it may require multiple unique components to be designed, qualified, produced, and kept in stock. In other cases, e.g. in RGB LCD-based projection systems, the maximum brightness may be limited by the components used, the engine volume may be large due to the many components, and the system cost may be high due to the many dedicated components. A way to combine pump light and luminescent light may be to use a polarizing beam splitter for the pump light, by which part of the light is reflected to the luminescent material and part is transmitted to a diffuser. However, as the maximum output power of available laser diode banks may be limited and, in addition, the maximum diameter of the (composed) laser beam may have to be limited in view of engine dimensions and cost of the optical components, there may be a need for laser-based light engines comprising multiple laser banks. Engines comprising two or more blue laser banks to provide diffused blue device light and luminescent light generated by exciting a luminescent material with part of the blue device light are known. Such prior-art architectures may depend on multiple polarization-dependent optical components, such as polarizing beam splitters, quarter wave plates, and polarization maintaining reflective diffusers, which may typically be relatively expensive components. Such prior-art architectures typically (also) depend on the application of dichroic beam splitters / combiners which, in particular when steep flanks of the spectral transmission / reflection curves are required and / or when multiple angles of incidence are to be handled, may be relatively expensive components.

[0010] Furthermore, prior art light engines comprising three laser banks may not provide CCT tunable configurations that can be operated at constant power, or at least not without using multiple polarization-dependent optical components.

[0011] 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.

[0012] According to a first aspect, the invention provides a light generating system (“system”) comprising two or more light generating devices, a luminescent material, a diffuser assembly, optics, and a light exit. The two or more light generating devices may be configured to generate device light. In embodiments, the light generating devices may comprise solid state light sources individually selected from the group comprising laser diodes, superluminescent diodes, and stacked multi -junction light-emitting diodes. Moreover, in embodiments, the two or more light generating devices may comprise (i) a first light generating device configured to generate first device light and (ii) a second light generating device configured to generate second device light. Further, in embodiments, the first light generating device may comprise a first laser bank. Especially, in embodiments, the first light generating device (for example the first laser bank) may comprise a first array comprising a plurality of first solid state light sources. In embodiments, (e.g. when the first light generating device comprises the first laser bank) the first solid state light sources may comprise first lasers. Similarly, in embodiments, the second light generating device may comprise a second laser bank. Especially, in embodiments, the second light generating device (for example the second laser bank) may comprise a second array comprising a plurality of second solid state light sources. In embodiments, (e.g. when the second light generating device comprises the second laser bank) the second solid state light sources may comprise second lasers. Furthermore, in embodiments, the optics may comprise redirection optical elements. The redirection optical elements may, in embodiments, comprise a first beam combiner and a second beam combiner. In embodiments, the first beam combiner may be configured to direct first device light received by the first beam combiner and second device light received by the first beam combiner in an optical path to another one of the redirection optical elements. Therefore, in embodiments, the first beam combiner may comprise a geometric beam combiner. In embodiments, the geometric beam combiner may comprise a plate comprising geometric-optical features that correlate to a geometrical distribution of the plurality of first solid state light sources and the plurality of second solid state light sources. Furthermore, in embodiments, the optics may be configured to direct in a first operational mode of the light generating system a part of the device light, comprising one or more of first device light and second device light, in an optical path to the luminescent material via the first beam combiner and the other one of the redirection optical elements. Additionally, in embodiments, the optics may be configured to direct in a first operational mode of the light generating system a part of the device light in an optical path to the diffuser assembly. In embodiments, the luminescent material may be configured to convert at least part of first device light received by the luminescent material and at least part of second device light received by the luminescent material into luminescent material light. Further, in embodiments, the diffuser assembly may comprise a diffuser. In embodiments, the diffuser may be configured to diffuse at least part of the device light (comprising one or more of first device light and second device light) received by the diffuser into diffused device light. Further, in embodiments, the second beam combiner may be configured to direct (yellow-green) luminescent material light received by the second beam combiner and (blue) diffused device light received by the second beam combiner in an optical path towards the light exit. Therefore, in embodiments, the second beam combiner may comprise a dichroic beam combiner. Moreover, in embodiments, the light generating system may be configured to generate in the first operational mode of the light generating system (white) system light comprising at least part of the diffused device light and at least part of the luminescent material light. Especially, in embodiments, the system light may be white light having a correlated color temperature selected from the range of 2000-12000 K, such as 2000-10000 K, and a color rendering index of at least 65. Hence, in embodiments, the invention provides a light generating system comprising two or more light generating devices, a luminescent material, a diffuser assembly, optics, and a light exit, wherein: (A) the two or more light generating devices may be configured to generate device light; wherein the light generating devices may comprise solid state light sources individually selected from the group comprising laser diodes, superluminescent diodes, and stacked multi -junction light-emitting diodes; wherein the two or more light generating devices may comprise (i) a first light generating device configured to generate first device light having a first centroid wavelength (Xci), wherein the first centroid wavelength (Xci) is selected from the wavelength range of 430-490 nm and (ii) a second light generating device configured to generate second device light having a second centroid wavelength (X^), wherein the first centroid wavelength (Xci) is selected from the wavelength range of 430-490 nm; wherein the first light generating device may comprise a first array comprising a (plurality of) first solid state light source(s); wherein the second light generating device may comprise a second array comprising a (plurality of) second solid state light source(s); (B) the optics may comprise redirection optical elements, wherein the redirection optical elements may comprise a first beam combiner and a second beam combiner; (C) the first beam combiner may be configured to direct first device light received by the first beam combiner and second device light received by the first beam combiner in an optical path to another one of the redirection optical elements; wherein the first beam combiner may comprise a geometric beam combiner, wherein the geometric beam combiner may comprise a plate comprising geometric-optical features that correlate to a geometrical distribution of the plurality of first solid state light sources and the plurality of second solid state light sources; (D) the optics may be configured to direct in a first operational mode of the light generating system (i) a part of the device light, comprising one or more of first device light and second device light, in an optical path to the luminescent material via the first beam combiner and the other one of the redirection optical elements, and (ii) a part of the device light in an optical path to the diffuser assembly; (E) the luminescent material may be configured to convert at least part of first device light received by the luminescent material and at least part of second device light received by the luminescent material into luminescent material light; (F) the diffuser assembly may comprise a diffuser; wherein the diffuser may be configured to diffuse at least part of the device light (, comprising one or more of first device light and second device light) received by the diffuser into diffused device light; (G) the second beam combiner may be configured to direct (yellow-green) luminescent material light received by the second beam combiner and (blue) diffused device light received by the second beam combiner in an optical path towards the light exit; wherein the second beam combiner may comprise a dichroic beam combiner; the first light generating device comprises a first laser bank comprising a plurality of first lasers; wherein the second light generating device comprises a second laser bank comprising a plurality of second lasers; and wherein the first array, the second array, and the first beam combiner are spatially arranged in relation to each other such that: the first device light is incident on a first side of the first beam combiner, the second device light is incident on a second side of the first beam combiner, the first device light and the second device light are combined by the first beam combiner to escape from the first beam combiner via the first side, and at least one of the first device light and the second device light undergoes at least one total internal reflection within the first beam combiner; (H) the light generating system may be configured to generate in the first operational mode of the light generating system (white) system light comprising at least part of the diffused device light and at least part of the luminescent material light, wherein the system light may be white light having a correlated color temperature selected from the range of 2000-12000 K and a color rendering index of at least 65.

[0013] Such a light generating system may provide a reduced cost yet high- performing system. The lower cost may be the result of minimization of the number of relatively expensive optical components. Further, the invention may provide system architectures enabling operational modes, which may result in highly efficient use of installed laser diode power. Hence, the light generating system of the invention may provide increased brightness, increased output power within a defined etendue and increased efficiency of the light generating system, resulting in lowest possible cost per unit of optical output power. The light generating system may further provide high color uniformity and the option of color tuneability. Yet further, the light generating system may be relatively eye-safe. In particular, the light generating system may be capable of providing well over 30 klm white light output by using an architecture comprising both polarization-based beam combining and dichroic-based beam combining. Thus, a compact, efficient, more robust, lower cost, and safe optical architecture is proposed. Furthermore, the light generating system may provide high brightness, high flux and high efficiency by using blue laser light for conversion via a luminescent converter material into luminescent light with a center wavelength in the yellowgreen spectral range and combine this with blue laser light and optionally with red laser light into white or colored output light. Such laser-phosphor configurations may be more efficient than configurations using direct green laser light and may provide better color rendering properties and enlarged color gamut areas as well. Hence, amongst others, the invention provides a laser-phosphor engine architecture comprising a geometric beam combiner.

[0014] The light generating system (or “system”) may thus comprise two or more light generating devices, a luminescent element, a diffuser assembly, optics, and a light exit. Here below, embodiments of the different elements of the light generating system will be described in further detail.

[0015] The light generating devices may be configured to generate device light. Therefore, in embodiments, the light generating devices may each comprise a solid-state light source. In embodiments, the two or more light generating devices may comprise (at least) a first light generating device and a second light generating device (and optionally further light generating devices). 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. 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 laser diode, a superluminescent diode, and a stacked multi -junction light-emitting diode (LED). In specific embodiments, the first light generating device may comprise at least two first solid-state light sources, such as e.g. two lasers. The first light generating device may herein, in embodiments, 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. In such embodiments, the first laser bank may comprise a first array comprising a plurality of first solid state light sources. Especially, in embodiments, the first laser bank may comprise a first array comprising a plurality of first lasers. For example, in embodiments, the first array may comprise an n*m array. In such embodiments, n and m may be individually selected from the range of 1-28, such as from the range of 2-20, like from the range of 4-14. Further, in embodiments, the first array may comprise an n*m array wherein for each row m a number of columns rm may be individually selected from the range of 1-28. Hence, in such embodiments, the different rows may comprise differing numbers of solid state light sources (especially lasers). However, in other embodiments, the different rows may comprise essentially the same numbers of solid state light sources (especially lasers). Additionally or alternatively, in embodiments, the first array may comprise an n*m array wherein for each column rm a number of rows m may be individually selected from the range of 1-28. Hence, in such embodiments, the different columns rm may comprise differing numbers of solid state light sources (especially lasers). However, in other embodiments, the different columns rm may comprise essentially the same numbers of solid state light sources (especially lasers). Furthermore, in embodiments, n and m may both be 1, i.e., the first laser bank may comprise a 1*1 array and may thus comprise a single (first solid state light source, especially) first laser. 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 (e.g. arranged in an array of lenses, see also further below). Especially, in embodiments, the laser bank may comprise an assembly of multiple collimating lenses configured correlating (optically and / or spatially) with the assembly of multiple laser diodes. 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. Depending on the desired output beam characteristics, additional beam shaping optics may be needed. Note that an array of solid-state light sources may provide multiple light generating devices, such as a first light generating device and a second light generating device. For instance, a subset of laser diodes of an array of laser diodes may be used as first light generating device, and its device light may at least partially follow another optical path than device light of another subset of laser diodes from that array (of laser diodes). Hence, in embodiments a single laser bank may be applied, of which the light is split in multiple portions, effectively providing multiple light generating devices. In general, this may imply the application of optics, allowing to divide the laser light of multiple subsets of lasers from the same bank into their respective (separate) beams of light that at least partially do not have identical optical paths (in the light generating system). The subsets may comprise one or more of the laser diodes of the laser bank. However, especially a single laser diode may only be comprised by a single subset. Notwithstanding such embodiments, of course also multiple laser banks may be used to provide multiple light generating devices.

[0016] Further, in embodiments, the first light generating device may especially be configured to generate first device light having a first centroid wavelength (Xci). Especially, in embodiments, (at least part of) the first device light may have a first centroid wavelength (Xci) selected from the wavelength range of 400-500 nm, such as from the range of 400-490 nm, like from the range of 430-490 nm. More especially, in embodiments, (at least part of) the first device light may have a first centroid wavelength (Xci) selected from the wavelength range of 440-490 nm, such as from the wavelength range of 450-480 nm, or such as from the wavelength range of 445-460 nm. Hence, in embodiments, the first device light may be blue light. The terms “blue light” or “blue emission”, and similar terms, may especially relate to light having a wavelength in the range of about 440-490 nm (including some violet and cyan hues). However, intensity at shorter wavelengths may also be possible, such as within the wavelength range of 400-440 nm. Especially, in embodiments the device light has a centroid wavelength selected from the blue wavelength range.

[0017] Similarly, in embodiments, the second light generating device may configured to generate second device light. Therefore, in embodiments, the second light generating device may comprise a second light source. 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 laser diode, a superluminescent diode, and a stacked multi -junction light-emitting diode (LED). In specific embodiments, the second light generating device may comprise at least two second solid state light sources, such as e.g., second lasers. 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 (see also above). In such embodiments, the second laser bank may comprise a second array comprising a plurality of second solid state light sources. Especially, in embodiments, the second laser bank may comprise a second array comprising a plurality of second lasers. For example, in embodiments, the second array may comprise an n*m array, as described above in relation to the first laser bank.

[0018] Further, in embodiments, the second light generating device may especially be configured to generate second device light having a second centroid wavelength (X^). Especially, in embodiments, (at least part of) the second device light may have a centroid wavelength (^2) selected from the wavelength range of 400-500 nm, such as from the range of 400-490 nm, like from the range of 430-490 nm. More especially, in embodiments, (at least part of) the second device light may have a second centroid wavelength (X^) selected from the wavelength range of 440-490 nm, such as from the wavelength range of 450-480 nm, or such as from the wavelength range of 445-460 nm. Hence, in embodiments, the second device light may be blue light.

[0019] In embodiments, the first light generating device and the second light generating device may especially be configured to provide first device light and second device light, respectively, to the optics. In embodiments, the optics may comprise redirection optical elements. Herein, a redirection optical element may especially refer to an optical element configured to receive and redirect one or more beams of light.

[0020] In particular, in embodiments, the optics (especially the redirection optical elements) may comprise a first beam combiner and a second beam combiner. Note that, in embodiments, a beam combiner may also have a beam splitting functionality (see also further below). Hence, herein instead of the term “beam combiner” also the term “beam splitter” or “redirection optical element” may be applied.

[0021] The fact that the optics may comprise a first beam combiner and a second beam combiner does not exclude the presence of other optics, and may also include the use of one or more further redirection optical elements (see also below).

[0022] In specific embodiments, the first light generating device and the second light generating device may especially be configured to provide first device light and second device light, respectively, to the first beam combiner. In such embodiments, the first beam combiner may thus (during operation) be configured in a light-receiving relationship with both the first light generating device and the second light generating device. The first beam combiner may thus be configured downstream of both the first light generating device and the second light generating device. 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”.

[0023] Herein, in embodiments, the first beam combiner may comprise a geometric beam combiner. A geometric beam combiner (GBC) may comprise a plate comprising geometric-optical features that may correlate to a geometrical distribution of light sources configured to provide light to the geometric beam combiner. As such, in embodiments, light from part of the light sources (configured to provide light to the GBC) may be reflected by the geometric beam combiner. In other words, light from part of the light sources (configured to provide light to the GBC) may be redirected (by the GBC) in a direction substantially different from the direction of the incident light. Conversely, in embodiments, light from another part of the light sources (configured to provide light to the GBC at a different location on the GBC than the previous part) may be transmitted by the geometric beam combiner. Therefore, in embodiments, at least part of the first beam combiner may comprise a light transmissive, especially a light transparent, material. In other words, light from part of the light sources (configured to provide light to the GBC) may be directed (by the GBC) in a direction substantially equal to the direction of the incident light. Such reflection or transmission of the light may, in embodiments, depend on the geometric-optical design of the geometric beam combiner. Hence, in embodiments, the first beam combiner may provide geometric (or spatial) beam combining functionality as it may combine two incident device light source beams into an output (or combined) beam with an etendue that may be smaller than the sum of the etendues of the two incident device light beams, where the etendue may refer to the smallest outer circumference of a light beam , i.e., independent of their polarization and / or wavelength.

[0024] For example, in embodiments, the light generating system may comprise a first light generating device comprising a single first laser and a second light generating device comprising a single second laser. In such embodiments, the first laser and the second laser may be configured to provide first and second device light, respectively, to the first beam combiner (i.e. the GBC) such that the first and second device light may be incident on different (spatial) locations of the geometric beam combiner. Especially, in such embodiments, the first laser and the second laser may be configured to provide first and second device light, respectively, to the first beam combiner (i.e. the GBC) from orthogonal directions (i.e. an optical axis of the first device light and an optical axis of the second device light incident on the GBC may be orthogonal relative to each other). The first beam combiner (i.e. the GBC) may, in such embodiments, be configured to (i) reflect one of the first device light and the second device light and to (ii) transmit the other one of the first device light and the second device light, such that the first device light and second device light may be combined into the same optical path (propagating from the first beam combiner). Hence, in such embodiments, the optical axis of the first device light and the optical axis of the second device light propagating from the GBC may have the same direction, i.e. may be parallel. Herein, the term “optical axis” (O) may be defined as an imaginary line that defines the path along which light propagates towards or from a respective element. For example, the optical axis of the first device light incident on the geometric beam combiner may be defined as an imaginary line that defines the path along which light propagates (from the first light generating device) to the geometric beam combiner. More especially, the optical axis (O) may coincide with the direction of the light with the highest radiant flux.

[0025] In some embodiments, the geometric beam combiner (or geometric beam redirector) may be configured to transmit or reflect light received by the geometric beam combiner in dependence of its angle of incidence relative to a surface normal (Ni) of the geometric beam combiner. Additionally or alternatively, in embodiments, the geometric beam combiner may be configured to transmit or reflect light received by the geometric beam combiner in dependence of its total internal reflection relative to the geometric beam combiner. In particular, the geometric beam combiner may be engineered such that light incident on different spatial locations on the geometric beam combiner may be differently redirected, e.g. transmitted or reflected. Especially, in embodiments, the geometric beam combiner may be engineered such that the transmissive and reflective optical features of the geometric beam redirector may be tailored to the geometries of the light sources in the light generating devices (e.g. the lasers in a laser bank). As such, in embodiments, the geometric beam combiner may be configured to combine device light received from two different optical paths (e.g. first device light and second device light orthogonally provided to the geometric beam redirector) into the same optical path (or direction). Such embodiments may be beneficial as optical power of different light generating devices may be combined without the need for expensive polarization based optical elements and / or differing wavelengths in the device light.

[0026] Hence, in embodiments, the (first beam combiner comprising) the geometric beam combiner (GBC) may comprise a plate comprising geometric-optical features that correlate to a geometrical configuration of the first light generating device and the second light generating device. In specific embodiments, the first light generating device may comprise a first laser bank comprising a plurality of first lasers and the second light generating device may comprise a second laser bank comprising a plurality of second lasers. In such embodiments, the (first beam combiner comprising) the geometric beam combiner (GBC) may comprise a plate comprising geometric-optical features that correlate to a geometrical distribution of the plurality of first lasers and the plurality of second lasers.

[0027] In embodiments, the first array, the second array, (optionally one or more optical elements, such as e.g. lenses or lens arrays,) and the first beam combiner may be spatially arranged in relation to each other such that the first device light may be incident on a first side of the first beam combiner. Additionally or alternatively, in embodiments, the first array, the second array, (optionally one or more optical elements) and the first beam combiner may be spatially arranged in relation to each other such that the second device light may be incident on a second side of the first beam combiner. Yet additionally or alternatively, in embodiments, the first array, the second array, (optionally one or more optical elements) and the first beam combiner may be spatially arranged in relation to each other such that the first device light and the second device light may be combined by the first beam combiner to escape from the first beam combiner via the first side. In such embodiments, at least one of the first device light and the second device light may undergo at least one total internal reflection within the first beam combiner.

[0028] In embodiments, such as indicated above, at least part of the first beam combiner may thus comprise a light (transmissive, especially a light) transparent material. For example, in embodiments, at least part of the first beam combiner may comprise a material selected from the group comprising: a glass material, a polymeric material (like PMMA or PC), and a ceramic material.

[0029] As can be derived from the above, in embodiments, the first beam combiner may be configured to direct first device light (received by the first beam combiner) and second device light (received by the first beam combiner) in a same optical path. Especially, in embodiments, the first beam combiner may be configured to direct first device light (received by the first beam combiner) and second device light (received by the first beam combiner) in an optical path to another one of the redirection optical elements.

[0030] In embodiments, the other one of the redirection optical elements may comprise one or more of a geometry-based redirection optical element (see also above), a polarization-based redirection optical element, a dichroic-based redirection optical element, and a neutral redirection optical element.

[0031] In embodiments via polarization multiplexing, device light from different light generating devices may be combined provided that they differ in (linear) polarization. For instance, s-polarized light and p-polarized light may be combined, or elliptically polarized light comprising relatively more p-polarization than s-polarization, and elliptically polarized light comprising relatively more s-polarization than p-polarization may be combined with a polarization-based redirection optical element (which may also be indicated as polarizing beam combiner or polarizing beam splitter).

[0032] Alternatively (or additionally), in embodiments via dichroic multiplexing, device light from different light generating devices may be combined provided that they differ in spectral power distribution. For instance, device light having different centroid wavelengths may be combined, or device light having (substantially) different spectral power distributions may be combined with a dichroic-based redirection optical element (which may also be indicated as dichroic beam combiner or dichroic beam splitter). In embodiments, the dichroic-based redirection optical element may essentially comprise a spectral filter, such as e.g. a high-pass spectral filter, a low-pass spectral filter, or a combination thereof (also referred to as a band-pass or band-block filter).

[0033] Yet further, in embodiments, the neutral redirection optical element may be configured to transmit or reflect light received by the neutral redirection optical element in dependence of Fresnel reflection of the light received by the neutral redirection optical element, therewith resulting in (two) separate beams. In embodiments, the neutral redirection optical element may especially comprise one or more stacks of dielectric layers configured to tune the beam splitting properties without specific (or intended) spectral or polarization preferences.

[0034] Herein, the optics may especially be configured to, in embodiments, direct in a first operational mode of the light generating system a part of the device light (comprising one or more of first device light and second device light) in an optical path to the luminescent material. The device light (comprising one or more of first device light and second device light) may, in such embodiments, especially be directed in an optical path to the luminescent material via the first beam combiner and the other one of the redirection optical elements. In embodiments, the luminescent material may be configured in the reflective mode. 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 such embodiments, the “other one of the redirection optical elements” as referred to above may especially comprise the second beam combiner. Especially, in such embodiments, the second beam combiner may comprise a (first) dichroic beam combiner (DBC), see also further below. Hence, in embodiments, device light (comprising one or more of first device light and second device light) may be directed in an optical path to the luminescent material via the first beam combiner and the second beam combiner (i.e. the (first) DBC).

[0035] In embodiments, the luminescent material may thus be configured (optionally via one or more further (optical) elements) in a light-receiving relationship with the second beam combiner. In other words, the luminescent material may, in such embodiments, be configured downstream of the second beam combiner. In embodiments, the luminescent material may be configured to convert at least part of the device light received by the luminescent material into luminescent material light. Especially, in embodiments, the luminescent material may be configured to convert at least 60%, such as at least 70%, especially at least 80%, more especially at least 90% of the device light received by the luminescent material into luminescent material light. Further, in embodiments, the luminescent material may be configured to convert at most 100%, such as at most 98%, especially at most 95%, more especially at most 90% of the device light received by the luminescent material into luminescent material light.

[0036] The term “luminescent material” especially refers to a material that can convert first radiati on, (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 downconversion. 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. 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<Xem), 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).

[0037] The term “luminescent material” may also refer to a plurality of different luminescent materials. Examples of possible luminescent materials are indicated below. 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. 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.

[0038] 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.

[0039] 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 AsBsOn 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%. 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.

[0040] Hence, in specific embodiments the luminescent material comprises a luminescent material of the type AsBsOn 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)3B50i2: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-xLux)3A150i2: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)3A150i2. Ce in garnets is substantially or only in the trivalent state, as is known to the person skilled in the art.

[0041] 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. In the present invention, especially xl>0, such as >0.2, like at least 0.8. Garnets with Y may provide suitable spectral power distributions.

[0042] 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-xsCexs^ALOn, wherein xl+x3=l, and wherein 0<x3<0.2, such as 0.001-0.1.

[0043] Alternatively or additionally, the luminescent material may comprise a luminescent material of the type AsSieNiuCe3, wherein A comprises one or more of Y, La, Gd, Tb and Lu, such as in embodiments one or more of La and Y.

[0044] In embodiments, the luminescent material may alternatively or additionally comprise one or more of MS:Eu2+and / or LSisNs Eu2and / or MAlSiHrEu2and / 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)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 CaAlSi Eu, the correct formula could be (Cao.98Euo.o2)AlSiN3. Divalent europium will in general replace divalent cations, such as the above divalent alkaline earth cations, especially Ca, Sr or Ba.

[0045] In embodiments, the luminescent material may comprise a luminescent material of the type M’xM2-2xAX6 doped with tetravalent manganese, wherein M’ comprises an alkaline earth cation, M comprises an alkaline cation, and x is in the range of 0-1, wherein A comprises a tetravalent cation, for instance comprising one or more of silicon and titanium, wherein X comprises a monovalent anion, at least comprising fluorine. A luminescent material of the type M’xM2-2xAX6 doped with tetravalent manganese is amongst others described in WO2013121355A1, which is herein incorporated by reference. Passages from WO2013121355A1 are also copied herein. Herein, M’xM2-2xAX6 doped with tetravalent manganese, may further also shortly be indicated as “phosphor”, i.e. the phrase " phosphor comprising M’xM2-2xAX6 doped with tetravalent manganese" may in an embodiment also be read as M’xM2-2xAX6 doped with tetraval ent manganese phosphor, or (tetraval ent) Mn-doped M’XM2-2XAX6 phosphor, or shortly "phosphor".

[0046] Relevant alkaline cations (M) are sodium (Na), potassium (K) and rubidium (Rb). Optionally, also lithium and / or cesium may be applied. In a preferred embodiment, M comprises at least potassium. In yet another embodiment, M comprises at least rubidium. The phrase “wherein M comprises at least potassium” indicates for instance that of all M cations in a mole M’xM2-2xAX6 , a fraction comprises K+and an optionally remaining fraction comprises one or more other monovalent (alkaline) cations (see also below). In another preferred embodiment, M comprises at least potassium and rubidium. Optionally, the M’XM2- 2xAXe luminescent material has the hexagonal phase. In yet another embodiment, the M’XM2- 2xAXe luminescent material has the cubic phase. Relevant alkaline earth cations (M’) are magnesium (Mg), strontium (Sr), calcium (Ca) and barium (Ba), especially one or more of Sr and Ba. In an embodiment, a combination of different alkaline cations may be applied. In yet another embodiment, a combination of different alkaline earth cations may be applied. In yet another embodiment, a combination of one or more alkaline cations and one or more alkaline earth cations may be applied. For instance, KRbo.sSro^sAXe might be applied. As indicated above, x may be in the range of 0-1, especially x<l. In an embodiment, x=0.

[0047] The term “tetravalent manganese” refers to Mn4+. This is a well-known luminescent ion. In the formula as indicated above, part of the tetravalent cation A (such as Si) is being replaced by manganese. Hence, M’xM2-2xAX6 doped with tetravalent manganese may also be indicated as M’xM2-2xAi-mMnmX6. The mole percentage of manganese, i.e. the percentage it replaces the tetravalent cation A will in general be in the range of 0.1-15 %, especially 1-12 %, i.e. m is in the range of 0.001-0.15, especially in the range of 0.01-0.12.

[0048] In an embodiment, M’xM2-2xAX6 comprises BGSiFe (indicated herein also as KSiF system). As indicated above, in another preferred embodiment, M’xM2-2xAX6 comprises KRbSiFe (herein also indicated as K,Rb system). As indicated above, part of silicon is replaced by manganese (i.e. the formula may also be described as K2Sii-mMnmF6 or KRbSii-mMnmF6, with m as indicated above, or as KRbSiFe:Mn and K2SiFe:Mn, respectively). As manganese replaces part of a host lattice ion and has a specific function, it is also indicated as “dopant” or “activator”. Hence, the hexafluorosilicate is doped or activated with manganese (Mn4+). In specific embodiments, the luminescent material may comprise (K,Rb)2SiFe:Mn4+. Alternatively or additionally, in embodiments the third luminescent material may comprise K2SiFe:Mn4+. Alternatively or additionally, in embodiments the third luminescent material may comprise K2TiFe:Mn4+. In embodiments, the third luminescent material may comprise K2(Si,Ti)Fe:Mn4+. As can be derived from the above, “ Si,Ti” may indicate one or more of Si and Ti.

[0049] Hence, when M (or A) in chemical formulas refer to n different elements, this may imply that the relevant formula may comprise for the M (or A) position in the formula essentially any permutation of the n different elements. For instance, when M=Ba,Sr,Ca or when M comprises one or more of Ba, Sr, Ca or when M refers to Ba,Sr,Ca, i.e. n=3, this may imply that in the formula Ba, Sr, Ca, (BaxSry), (BaxCay), (CaxSry), or (BaxSryCaz), may be available, wherein in general x+y+z=l. Referring to e.g. M’xM2-2xAX6, this may refer to e.g. one or more of K2SiFe:Mn4+and of Rb2SiFe:Mn4+, or (KxRby)2SiFe:Mn4+, etc. Referring to (Ba,Sr,Ca)AlSiN3:Eu, this may imply BaAlSiN3:Eu, SrAlSiN3:Eu, CaAlSiN3:Eu, (BaxSry)AlSiN3:Eu, (BaxCay)AlSiN3:Eu, (CaxSry)AlSiN3:Eu, or (BaxSryCaz)AlSiN3:Eu. Referring to e.g. A3BsOi2:Ce, wherein A in embodiments comprises one or more of Y, La, Gd, Tb and Lu, this may imply Y3BsOi2:Ce, La3BsOi2:Ce, GdBsOn Ce, TbsBsOn Ce, Lu3BsOi2:Ce, but also e.g. (Yx,Gdy)3B50i2:Ce, (Yx,Luy)3B50i2:Ce, (Gdx,Luy)3B50i2:Ce, (Yx,Gdy,Luz)3B50i2:Ce, etc. etc., with hereby only limiting for the sake of economy to unary, binary, and ternary examples, though quaternary and higher examples are not excluded herein. Further, indications like “K,Rb” or Ba,Sr,Ca, and similar indications (see also above), may indicate one or more of such elements. Hence, (K,Rb)2SiFe:Mn4+, may e.g. refer to K2SiFe:Mn4+and of Rb2SiFe:Mn4+, or (KxRby)2SiFe:Mn4+. Also herein in general x+y=l. Hence, when M (or A) may refer to n different elements, with n being at least two, 2n-l permutations may in principle be possible. 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.

[0050] 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.

[0051] The term “luminescent material” herein especially relates to inorganic luminescent materials.

[0052] 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.

[0053] Quantum dots are small crystals of semiconducting material generally having a width or diameter of only a few nanometers. When excited by incident light, a quantum dot emits light of a color determined by the size and material of the crystal. Light of a particular color can therefore be produced by adapting the size of the dots. Most known quantum dots with emission in the visible range are based on cadmium selenide (CdSe) with a shell such as cadmium sulfide (CdS) and zinc sulfide (ZnS). Cadmium free quantum dots such as indium phosphide (InP), and copper indium sulfide (CuInS?) and / or silver indium sulfide (AglnS?) can also be used.

[0054] Instead of quantum dots or in addition to quantum dots, also other quantum confinement structures may be used. The term “quantum confinement structures” should, in the context of the present application, be understood as e.g. quantum wells, quantum dots, quantum rods, tripods, tetrapods, or nano-wires, etcetera.

[0055] In general, the luminescent material may give rise to quite a lot of thermal dissipation. Therefore, in embodiments, this material may preferably be applied onto a rotating wheel, enabling superior thermal spreading and cooling without the need for e.g. active water cooling, and thereby enabling maximum possible irradiance values.

[0056] As mentioned above, in embodiments, the luminescent material may thus be configured in the reflective mode. In alternative embodiments, the luminescent material may be configured in the transmissive mode. 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 such embodiments, the luminescent material may be applied in thermal contact with a thermally conductive element. An element may be considered in “thermal contact” with another element if it can exchange energy through the process of heat. In embodiments, thermal contact can be achieved by physical contact. In embodiments, thermal contact may be achieved via a thermally conductive material, such as a thermally conductive glue (or thermally conductive adhesive). Thermal contact may also be achieved between two elements when the two elements are arranged relative to each other at a distance of equal to or less than about 10 gm, though larger distances, such as up to 100 gm may be possible. The shorter the distance, the better the thermal contact. The distance may be the distanced between two respective surfaces of the respective elements. The distance may be an average distance. When the two elements are configured at a distance from each other, an intermediate material may be configured in between, though in other embodiments, the distance between the two elements may filled with a gas, liquid, or may be vacuum. When an intermediate material is available, the larger the distance, the higher the thermal conductivity may be useful for thermal contact between the two elements. However, the smaller the distance, the lower the thermal conductivity of the intermediate material may be (of course, higher thermal conductive materials may also be used).

[0057] Hence, in embodiments the luminescent material may be configured in thermal contact with a thermally conductive material. For instance, the luminescent material may be configured in thermal contact with a thermally conductive element.

[0058] A thermally conductive element may especially comprise thermally conductive material. A thermally conductive material may especially have a thermal conductivity of at least about 20 W / (m*K), like at least about 30 W / (m*K), such as at least about 100 W / (m*K), like especially at least about 200 W / (m*K). In yet further specific embodiments, a thermally conductive material may especially have a thermal conductivity of at least about 10 W / (m*K). In embodiments, the thermally conductive material may comprise one or more of copper, aluminum, silver, gold, silicon carbide, aluminum nitride, boron nitride, aluminum silicon carbide, beryllium oxide, a silicon carbide composite, aluminum silicon carbide, a copper tungsten alloy, a copper molybdenum carbide, carbon, diamond, and graphite. Alternatively, or additionally, the thermally conductive material may comprise or consist of aluminum oxide. In embodiments, the thermally conductive element may comprise one or more of a heatsink, a heat spreader, and a two-phase cooling device. In yet other embodiments, the thermally conductive element may be configured in thermal contact with one or more of a heatsink, a heat spreader, and a two-phase cooling device, and may e.g. transfer heat to such heatsink, heat spreader, or two-phase cooling device, via another thermally conductive element. Furthermore, in embodiments where the luminescent material is configured in the transmissive mode, a dichroic coating may be applied on the upstream surface of the luminescent material. Additionally or alternatively, in embodiments where the luminescent material is configured in the transmissive mode, a dichroic coating may be configured on a face of a separate transmissive optical component (e.g. a plate such as a glass plate or a ceramic plate) configured upstream of the luminescent material. Especially, in such embodiments, the dichroic coating may be configured to transmit the incident device light and to reflect the luminescent light. Such embodiments may be beneficial as the dichroic coating may help prevent significant loss of luminescent light that may be emitted in the backward direction (i.e. in a direction back to the light generating devices). Furthermore, such embodiments may provide eye-safety protection against failure of the luminescent material (i.e., in case of degradation / cracking of the luminescent material), as device light may be prevented from reaching the output of the light engine by being transmitted by the second beam combiner.

[0059] For further improving the eye-safety of the light generating system, in embodiments, a small-angle reflective diffuser may additionally be applied downstream of the luminescent material. Such embodiments may help ensure intrinsic eye safety for the luminescent material channel, as the luminescent material may be the most vulnerable component upon laser light irradiation due to the significant thermal dissipation that may result from conversion losses.

[0060] Furthermore, in such embodiments where the luminescent material may be configured in the transmissive mode, the “other one of the redirection optical elements” as referred to above may especially comprise a first beam splitter. Hence, in embodiments, the redirection optical elements may comprise a first beam splitter. In embodiments, the first beam splitter may be configured downstream of the first beam combiner. As such, in embodiments, the first beam splitter may be configured in a light-receiving relationship with the first beam combiner, optionally via one or more further (optical) elements (such as e.g. a retarder plate and / or an integrator). However, in alternative embodiments, the first beam splitter may be configured upstream of the first beam combiner, i.e., the first beam combiner may be configured in a light-receiving relationship with the first beam splitter (optionally via one or more further (optical) elements). Moreover, in embodiments, (during operation) the first beam splitter may be configured upstream of both the luminescent material and the diffuser assembly. The first beam splitter may, in embodiments, be configured to direct at least part of the device light received by the first beam splitter in an optical path to the diffuser assembly. Hence, in embodiments, the diffuser assembly may be configured in a light-receiving relationship with the first beam splitter. Additionally, in embodiments, the first beam splitter may be configured to direct at least another part of the device light received by the first beam splitter in an optical path to the luminescent material. Hence, in embodiments, the luminescent material may be configured in a light-receiving relationship with the first beam splitter.

[0061] The first beam splitter may especially be configured to redistribute device light (comprising one or more of first device light, second device light, and optionally further device light) received by the first beam splitter over the luminescent material and the diffuser assembly. Especially, in embodiments, the first beam splitter may comprise a (first) (optionally partially) polarizing beam splitter ((P)PBS), see also above and further below. In such embodiments, the (first, second, and optionally further) device light received by the first beam splitter may comprise (linearly) polarized light (see also further below). Especially, in embodiments, the first beam splitter may thus provide the functionality of polarization-based redistribution of device light over (i) the conversion channel and (ii) the diffusion channel. However, in embodiments, the first beam splitter may have additional functionalities, which will be described in more detail further below. Especially, in embodiments, the polarizing beam splitter may be configured to transmit (first and / or second) device light comprising a first linear polarization, whereas it may be configured to reflect (first and / or second) device light comprising a second linear polarization (different from the first linear polarization). Alternatively, in embodiments, the polarizing beam splitter may be configured to reflect (first and / or second) device light comprising a first linear polarization, whereas it may be configured to transmit (first and / or second) device light comprising a second linear polarization (different from the first linear polarization). The polarization of the device light may, in embodiments, especially be controlled by a polarization control system, see also further below. In specific embodiments, the first beam splitter may comprise a (partially) polarizing beam splitter, wherein device light reaching the polarizing beam splitter may comprise polarized light; and wherein the polarizing beam splitter may be configured (a) to transmit device light (received by the first beam splitter) comprising a first linear polarization and to reflect device light (received by the first beam splitter) comprising a second linear polarization, different from the first linear polarization, or (b) to reflect device light (received by the first beam splitter) comprising a first linear polarization and to transmit device light (received by the first beam splitter) comprising a second linear polarization, different from the first linear polarization. Hence, in embodiments, device light (comprising one or more of first device light, second device light and optionally further device light) may be directed in an optical path to the luminescent material via the first beam combiner and the first beam splitter (i.e. the (first) PBS).

[0062] In embodiments, the luminescent material may thus be configured (optionally via one or more further (optical) elements) in a light-receiving relationship with the first beam splitter (rather than or in addition to the second beam combiner as described above). In other words, the luminescent material may, in such embodiments, be configured downstream of the first beam splitter.

[0063] In alternative embodiments, the first beam splitter may comprise a neutral redirection optical element, such as especially a neutral beam splitter (NBS), see also above and further below. In such embodiments, the first beam splitter may be configured to redistribute device light over the conversion channel and the diffusion channel in dependence of the configuration of the neutral beam splitter (i.e. independently of the polarization and / or wavelength of the device light received by the neutral beam splitter). Especially, in embodiments, the neutral beam splitter may be configured to direct x% of (device) light received by the neutral beam splitter in an optical path to the diffuser assembly. In such embodiments, the neutral beam splitter may further be configured to direct 100-x% of (device) light received by the neutral beam splitter in an optical path to the luminescent material. Hence, in embodiments, the neutral beam splitter may be configured to have a split ratio of x / (100-x). In embodiments, x may be selected from the range of 2-98, such as selected from the range of 20-80, like selected from the range of 30-70. For example, in embodiments, 50% (i.e. x=50) of device light received by the neutral beam splitter (i.e. in embodiments the first beam splitter) may be directed to the diffuser assembly, and 50% (i.e. 100-x=50) of device light received by the neutral beam splitter (i.e. in embodiments the first beam splitter) may be directed to the luminescent material. In general, it may be desired to provide more than 50% of all blue optical power to the luminescent material. Therefore, in embodiments, x may be selected from the range of <50%, such as from the range of <40%, like from the range of <30%. Furthermore, in embodiments, the two or more light generating devices may have different optical powers (e.g. the first light generating device (i.e. first laser bank) and the second light generating device (i.e. second laser bank) may have a different number of lasers. In such embodiments, it may be desirable to select x from the range of >50%, such as from the range of >60%, like from the range of >70%.

[0064] In embodiments, the first beam splitter may thus provide the functionality of polarization and wavelength independent redistribution of device light over (i) the conversion channel and (ii) the diffusion channel. In specific embodiments, the first beam splitter may comprise a neutral beam splitter configured to direct x% of light received by the neutral beam splitter in an optical path to the diffuser assembly and to direct 100-x% of light received by the neutral beam splitter in an optical path to the luminescent material (200), wherein x may be selected from the range of 2-98.

[0065] As described above, in embodiments, the optics may thus be configured to direct a part of the device light in an optical path to the luminescent material. Additionally, in embodiments, the optics may be configured to direct in a first operational mode of the light generating system a part of the device light (comprising one or more of first device light, second device light, and further device light, see also further below) in an optical path to the diffuser assembly.

[0066] In embodiments, the diffuser assembly may comprise (at least) a diffuser. The diffuser may, in embodiments, be configured to diffuse (or scatter) at least part of the device light received by the diffuser. Especially, the diffuser may be configured to diffuse at least 60%, such as at least 70%, especially at least 80%, more especially at least 90% of the device light received by the diffuser into diffused device light. In specific embodiments, the diffuser may be configured to diffuse (or scatter) at least part of the device light, comprising one or more of first device light and second device light, received by the diffuser. However, in alternative embodiments, the diffuser may be configured to diffuse (or scatter) at least part of the device light, comprising further (e.g. third) device light, received by the diffuser. Examples and further embodiments of the diffuser (assembly) will be described in more detail below.

[0067] In an operational mode of the light generating system, the system may thus be configured to generate (e.g. yellow-green) luminescent material light at the luminescent material and (e.g. blue and / or red) diffused device light at the diffuser. In embodiments, the second beam combiner may be configured downstream of both the luminescent material and the diffuser assembly. As such, in embodiments, the second beam combiner may be configured in a light-receiving relationship with both the luminescent material and the diffuser assembly. As described above, in embodiments, the second beam combiner may comprise at least a (first) dichroic beam combiner. Especially, the second beam combiner may be configured to dichroically combine the luminescent material light and the diffused device light (received by the second beam combiner) into a same optical path. Hence, in embodiments, the second beam combiner may be configured to direct the (e.g. yellow-green) luminescent material light received by the second beam combiner and the (e.g. blue and / or red) diffused device light received by the second beam combiner in an optical path towards the light exit.

[0068] The light exit may thus, in embodiments, be configured in a light-receiving relationship with the second beam combiner. As such, in embodiments, the light generating system may thus be configured to generate diffused device light and luminescent material light. Especially, in the first operational mode of the light generating system, the light generating system may be configured to generate system light comprising at least part of the diffused device light and at least part of the luminescent material light. In specific embodiment, the system light may thus be white light.

[0069] The term “white light”, and similar terms, herein, is 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 the table below, the percentage of blue light in white light at different correlated color temperatures (CCT) are shown, for a color rendering index of about 80. The remaining part of the white light is luminescent material light, in the visible light.

[0070] 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. Yet further, 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.

[0071] In embodiments, in an operational mode of the light generating system, the system light may especially be white light having a correlated color temperature selected from the range of 2000-12000 K, like a correlated color temperature selected from the range of 2000-10000. In further embodiments, in an operational mode of the light generating system, the system light may have a correlated color temperature selected from the range of 6000-10000 K, like selected from the range of 6500-8000 K. Additionally or alternatively, in embodiments, in an operational mode of the light generating system, the system light may especially be white light having a color rendering index of at least 60, such as at least 65, like at least 70, especially at least 80, more especially at least 90.

[0072] As described above, in embodiments, the luminescent material may be configured either in the transmissive mode or in the reflective mode. Similarly, in embodiments, the diffuser may be configured either in the transmissive mode or in the reflective mode. In specific embodiments, one of the luminescent material and the diffuser assembly may be configured in the transmissive mode and the other one of the luminescent material and the diffuser assembly may be configured in the reflective mode. Alternatively, in embodiments, the luminescent material and the diffuser assembly may both be configured in the transmissive mode. Yet alternatively, in embodiments, the luminescent material and the diffuser assembly may both be configured in the reflective mode.

[0073] Hence, in specific embodiments, the diffuser may be configured in the reflective mode (i.e. the diffuser may comprise a reflective diffuser). Therefore, in embodiments, the reflective diffuser may be (diffuse) reflective for (one or more of first, second and further) device light. In embodiments, the reflective diffuser may comprise a surface diffuser, a volume diffuser, or a combination of a surface and volume diffuser. The reflective diffuser may, in embodiments, comprise one or more materials selected from the group comprising: a glass with high transmission in the spectral range of the (first and second) device light, a silicone-based material, and a transparent ceramic material such as e.g. sapphire. Especially, in embodiments, the reflective diffuser may comprise one (or more) of: a small angle scattering metallic substrate, a white ceramic reflector, a patterned glassbased substrate with a (deposited metallic or (layered) dielectric) reflective coating, a combination of optical micro-structures with specular reflective elements, a combination of a solid optical body with a diffuse reflector, a combination of a structured surface with a dichroic or thin film deposited reflector, and a combination of a total internal reflector element with additional surface structuring. The reflective diffuser may especially be selected based on preferred system characteristics, such as thermal management, bulkiness, and cost.

[0074] In specific embodiments, the reflective diffuser may comprise a small angle diffuser. Especially, in some embodiments, the reflective diffuser (comprising the small angle diffuser) may be configured to provide an angular spread of diffusion where as a function of a scatter angle 0, the intensity 1(9) of the diffused (or scattered) light may correspond to a function of cosn(9), wherein n may be selected from the range of 10-100, like from the range of 20-100, such as from the range of 30-90. However, in other embodiments (when the diffuser comprises e.g. a top-hat diffuser), the reflective diffuser (comprising the small angle diffuser) may be configured to provide an angular spread of diffusion corresponding to one or more of a top-hat diffusion, or another engineered diffusion. In other words, in embodiments, the reflective diffuser may (comprise a small angle diffuser that may) be configured to redistribute incoming first device light such that the diffused beam (comprising first device light) propagating from the reflective diffuser may have a full width at half maximum (FWHM) selected from the range of 5-60°, such as from the range of 10-50°, like from the range of 10-40°, especially from the range of 12-30°. In the embodiments described here, the FWHM may especially refer to the diffused beam (comprising first device light) and therefore may be the result of both the divergence of the incident beam and the diffusion by the reflective diffuser.

[0075] In embodiments, the diffuser assembly may comprise the reflective diffuser and one or more optical elements, such as e.g. one or more lenses. In specific embodiments, the diffuser assembly may comprise (at least) a (reflective) diffuser, a condenser optical element, and a collecting optical element. Embodiments wherein the diffuser assembly comprises further (optical) elements are herein not excluded. Especially, in embodiments, the diffuser may comprise a reflective diffuser. Additionally or alternatively, in embodiments, the diffuser may comprise a (partially) transmissive diffuser combined with a reflective optical component configured behind (relative to a plane of incidence of) the transmissive diffuser. In such embodiments, the reflective optical component may e.g. comprise a (specular) mirror coating configured on the diffuser and / or a discrete specular mirror configured externally (and not in optical contact) of the diffuser, see also further below.

[0076] In embodiments, the condenser optical element may be configured upstream of the reflective diffuser. As such, in embodiments, the condenser optical element may be configured to receive device light (originating from one or more of the light generating devices) and propagate the device light in an optical path to the diffuser. Therefore, in embodiments, the condenser optical element may be transmissive for (one or more of first, second and further) device light. Especially, in embodiments, the condenser optical element may be configured to condense or focus the device light received by the condenser optical element. The condenser optical element may thus, in embodiments, be configured to provide a focused beam of device light in an optical path to the diffuser.

[0077] The condenser optical element may, in embodiments, comprise a lens. Especially, in embodiments, the condenser optical element may comprise a surface configured to condense an incoming parallel beam of light, such as a lens surface. In embodiments, the condenser optical element may for example comprise one or a curved lens surface, a Fresnel-type lens surface, and a metasurface (i.e., a flat textured surface). Especially, in embodiments, the condenser optical element may comprise an aspherical lens. However, in alternative embodiments (in dependence on desired requirements for the out-put system light), the condenser optical element may also comprise a spherical lens. In embodiments, the condenser optical element may comprise a lens with an optical diameter selected from the range of 15-60 mm, such as from the range of 20-50 mm, like from the range of 25-40 mm. Such embodiments may provide the benefit that the diameter of the condenser optical element may be large enough to accommodate an incoming beam of device light, while not being too bulky so that it may still fit in the light generating system.

[0078] Furthermore, in embodiments, the condenser optical element may comprise a material having low absorption for (at least) the spectral range of the device light. Especially, in embodiments, the condenser optical element may comprise a material having an absorption coefficient selected from the range of <0.01 cm’1for the spectral range of the received device light. More especially, in embodiments, the condenser optical element may comprise a material having an absorption coefficient selected from the range of <0.005 cm’1, such as from the range of <0.01 cm’1, for the spectral range of the received device light.

[0079] The condenser optical element may thus be configured to provide a focused beam of device light in an optical path to the diffuser. Hence, in embodiments, the diffuser may be configured in a light-receiving relationship with the condenser optical element. The diffuser may especially be configured to receive the focused beam of device light (originating from the condenser optical element) and reflect the device light in an optical path to the collecting optical element. Especially, in embodiments, the diffuser may be configured to diffuse and reflect the focused beam of device light received by the diffuser. The diffuser may thus, in embodiments, be configured to provide a diffused beam of device light in an optical path to the collecting optical element. In embodiments, the focused beam of device light (provided by the condenser optical element) may have an optical axis relative to the diffuser. Especially, in embodiments, relative to the diffuser the incident focused beam of device light may have an (incident) optical axis (Oi). Hence, in embodiments, the (incident) optical axis (Oi) may comprise an optical axis of light incident on the diffuser. Conversely, in embodiments, the diffused device light (provided by the diffuser) may have an optical axis relative to the diffuser. Especially, in embodiments, relative to the diffuser the reflected diffused device light may have an (reflection) optical axis (Or). Hence, in embodiments, the (reflection) optical axis (Or) may comprise an optical axis of light reflected from the diffuser. In embodiments, the (incident) optical axis (Oi) and the (reflection) optical axis (Or) may have a mutual angle (P). Especially, in embodiments, the mutual angle (P) may be selected from the range of 70°<P<150°, such as from the range of 80°<P<140°, like from the range of 80°<P<l 10°, especially from the range of 85°<P<100°. In embodiments, the (incident) optical axis (Oi) of the incident focused beam comprising the first device light may correspond to an average angle of incidence of the first device light on (a plane of incidence of) the diffuser. Conversely, the (reflection) optical axis (OR) of the reflected diffused beam comprising the first device light may correspond to an average angle of reflectance of the first device light from (a plane of incidence of) the diffuser. Especially, in embodiments, average angles of incidence and / or reflection may be defined in an incidence plane of the diffuser with relation to the normal of said incidence plane. In specific embodiments, the average angle of incidence (of the first device light on the diffuser) and the average angle of reflection (of the first device light from the diffuser) may be symmetrical around the normal of the plane of incidence. Hence, in such embodiments, the average angles of incidence and reflection may be derived from the value of the mutual angle (P). Hence, in embodiments, the diffuser may be configured in a non-collinear (or non-coaxial) configuration, i.e., the incoming beam of light and the outgoing beam of light may not be collinear. Especially, in embodiments, the incoming beam of light and the outgoing beam of light may be orthogonal relative to each other. In other words, the mutual angle (P) may be 90°, i.e., the (incident) focused beam of device light may be essentially perpendicular to the (reflected) beam of diffused device light. However, a mutual angle (P) of exactly 90° may not be necessary. A smaller or larger mutual angle (P) may be provided in view of the desired architecture or design of the system. In embodiments, the mutual angle (P) may be at least 75, such as at least 85. Such embodiments may be beneficial as such a mutual angle (P) allows for the configuration of the condensing optical element and the collecting optical element at (about) their respective focal distances from the diffuser as measured respectively on the incident optical axis (Oi) and the reflection optical axis (Or). In case of a smaller mutual angle (P), the condensing and collecting optical elements may be limited in size due to the available space, which may lead to a loss of light. In case of larger angles, the condensing and collecting optical elements may be less (or even not at all) limited in size.

[0080] The diffuser may, in embodiments, thus be configured to diffuse (or scatter) (at least the first) device light received by the diffuser. Especially, in such embodiments, the diffuser may comprise a reflective diffuser. Alternatively, in embodiments, the diffuser may comprise a transmissive diffuser combined with a (specular) reflective optical component configured behind (relative to a plane of incidence of) the transmissive diffuser. For example, the transmissive diffuser may comprise optical micro-structures configured to provide (both) transmissive and reflective diffusion of light received by the diffuser. In such embodiments, the reflective optical component may be configured to reflect transmi ssively diffused light that may otherwise be lost. Therefore, the reflective optical component may e.g. comprise a (specular) mirror coating configured on the diffuser and / or a discrete specular mirror configured externally (and not in optical contact) of the diffuser. Hence, in such embodiments, the diffuser may comprise a combination of optical micro-structures with a specular reflective element(s).

[0081] Further, the diffuser may, in embodiments, thus be configured to provide a beam of diffused device light in an optical path to the collecting optical element. Hence, in embodiments, the collecting optical element may thus be configured in a light-receiving relationship with the diffuser. In other words, the collecting optical element may be configured downstream of the diffuser. The collecting optical element may especially be configured to receive (or collect) the diffused device light (originating from the diffuser). In embodiments, the collecting optical element may be configured to collimate the received diffused device light to provide a collimated beam of diffused device light in an optical path to the second beam combiner. Note that, in embodiments, the collimated beam of diffused device light may propagate via one or more further (optical) elements configured in the optical path between the collecting optical element and the second beam combiner.

[0082] In embodiments, the collecting optical element may thus be transmissive for the diffused device light. Especially, in embodiments, the collecting optical element may be configured to collect and collimate the beam of diffused device light received by the collecting optical element. The collecting optical element may thus, in embodiments, be configured to provide a collimated beam of diffused device light in an optical path to the second beam combiner.

[0083] The collecting optical element may, in embodiments, comprise a lens. Especially, in embodiments, the collecting optical element may comprise an aspherical lens. However, in alternative embodiments (in dependence on desired requirements for the out-put system light), the collecting optical element may also comprise a spherical lens. In embodiments, the collecting optical element may comprise a lens with an optical diameter selected from the range of 15-60 mm, such as from the range of 20-50 mm, like from the range of 25-40 mm. Such embodiments may provide the benefit that the diameter of the collecting optical element may be large enough to accommodate an incoming beam of diffused device light propagating from the diffuser, while not being too bulky so that it may still fit in the light generating system.

[0084] Furthermore, in embodiments, the collecting optical element may comprise a material having low absorption for (at least) the spectral range of the device light. Especially, in embodiments, the collecting optical element may comprise a material having an absorption coefficient selected from the range of <0.01 cm’1for the spectral range of the received device light. More especially, in embodiments, the collecting optical element may comprise a material having an absorption coefficient selected from the range of <0.005 cm’1, such as from the range of <0.01 cm’1, for the spectral range of the received device light.

[0085] Note that, in embodiments, the condensing optical element and the collecting optical element may comprise essentially the same type of optical element. However, this may not necessarily be the case.

[0086] In embodiments, the condensing optical element may comprise a single positive lens. A second single positive lens may further be applied for the collecting (or collimating) optical element configured to collect the diffused device light along a path that is different from that of the incident light.

[0087] In some embodiments, the condenser optical element and the collecting optical element may have the same focal length. In alternative embodiments, the condenser optical element and the collecting optical element may have a different focal length. Hence, in embodiments, the condenser optical element may have a condenser focal length. Similarly, in embodiments, the collecting optical element may have a collector focal length. In embodiments, the condenser focal length and the collector focal length may differ by at least 10%, such as by at least 15%, like by at least 20%. Further, in embodiments, the condenser focal length and the collector focal length may differ by at most 150%, like by at most 100%. An advantage thereof may be that a spot size of the focused beam comprising first device light on the diffuser may be set independently of the magnification of imaging optical elements (such as the collecting optical element) configured between the diffuser and the light exit.

[0088] In general, in embodiments, a longer focal length may be preferred for the condenser optical element as the incoming light may have less divergence. Conversely, in embodiments, to collect the reflectively diffused light which may have larger divergence angles, assuming a more or less constant maximum diameter of the incoming and outgoing collimated beams (and respective optical components), a (relatively) shorter focal distance may be preferred. Such embodiments may especially be advantageous in improving system efficiency. Furthermore, in such embodiments and optionally with an additional optical element (such as e.g. a lens) magnification to the system output may be set independently.

[0089] In embodiments, the diffuser, the condenser optical element, and the collecting optical element may be configured such that the diffuser is in the focal plane of both the condenser optical element and the collecting optical element. This may, however, not necessarily be the case. The herein described non-collinear diffuser assembly may allow for more freedom in the choice of optical elements and their respective positions in the light generating system. In embodiments, the condenser lens may be configured to create a spot of first device light on (the surface of) the diffuser. Especially, in embodiments, the condenser lens may be configured to create a spot of first device light being either sharp, i.e., in focus, or vague, i.e., out-of-focus. Furthermore, in embodiments, a non-imaging condenser optical element with an out-of-focus placement of the diffuser may also be applied to reduce hot spots of the device light. The diffuser may, in embodiments, be configured to diffuse the device light, such that the angular distribution may be scrambled, while the spot size may be maintained. Conversely to the condenser optical element, in embodiments, for the collecting optical element applies that it may be configured to re-collimate light received from the diffuser. In embodiments, the collecting optical element may thus be configured to recollimate a spot of diffused device light, which may be in the focal plane of the collector optical element or optionally not in the focal plane. In some embodiments, the collecting optical element may (even) comprise two lenses, such that its focal strength may be improved. Hence, in embodiments, the diffuser may be configured out of a focal plane of one or more of the condenser optical element and the collecting optical element. Such embodiments may enable a wider range of spot sizes on the reflective diffuser and consequently a wider range of beam angles and the final cross-section dimensions of the outgoing diffused beam of first device light. Therewith, good color uniformity in the system light may be achieved.

[0090] In embodiments, the diffuser assembly may thus comprise a non-collinear diffuser assembly, wherein the diffuser may be configured in a reflective mode, such that the optical axis (Oi) of incoming device light and the optical axis (Or) of outgoing diffused device light (relative to the diffuser) may have an orthogonal direction relative to each other.

[0091] Alternatively to the above described, in embodiments, the diffuser may be configured in the transmissive mode, such that the optical axis (Oi) of incoming device light and the optical axis (Or) of outgoing diffused device light (relative to the diffuser) may have a parallel direction relative to each other. In other words, in such embodiments, the diffuser may be configured such that a direction of incoming device light and a direction of outgoing diffused device light (relative to the diffuser) may be parallel or collinear. In such embodiments, the incoming (first, second, and / or further) device light may especially comprise polarized light. Especially, in specific embodiments, the (first, second, and / or further) device light reaching the diffuser assembly may comprise linear polarized light, such as e.g. p-polarized light or s-polarized light.

[0092] The diffuser assembly may further, in embodiments, comprise a polarization converter. Especially, in embodiments, the polarization converter may comprise a birefringent rotator, more especially a X / 4 waveplate (or quarter waveplate). As known from the art, a waveplate or retarder is an optical device that may alter the polarization state of a light wave travelling through it depending on the orientation of the waveplate relative to the propagation direction and the state of polarization of the light wave. A halfwave plate may shift the polarization direction of linear polarized light (especially from s to p or from p to s polarization). Conversely, a quarter-wave plate may convert linear polarized light into elliptically (such as especially circularly) polarized light (and vice versa). Especially, herein, in embodiments, the quarter waveplate may be configured to convert linear polarized light received by the quarter waveplate into elliptical (such as especially circularly) polarized light. Additionally or alternatively, in embodiments, the quarter waveplate may be configured to convert elliptical polarized light (such as especially circularly polarized light) received by the quarter waveplate into linear polarized light. The X / 4 waveplate may especially be configured in an optical path between (relative to the propagation of light through the system) the redirection optical elements and the diffuser. As such, the redirection optical elements (such as e.g. the second beam combiner) may thus be configured to direct (first, second, and / or further) device light received by the redirection optical elements and comprising (either) the first linear polarization or the second linear polarization (optionally via optics) to the polarization converter (i.e. the quarter waveplate). The quarter waveplate may, in embodiments, be configured to convert device light received by the quarter waveplate comprising a linear polarization into device light having a (first) circular polarization. At the diffuser, in embodiments, the device light having the (first) circular polarization may be diffused into (first) diffused device light having a second circular polarization. Therefore, in embodiments, the quarter waveplate may also be configured to convert (first) diffused device light received by the quarter waveplate (via the diffuser) and having the (second) circular polarization into (first) diffused device light comprising a linear polarization. For example, in embodiments, p-polarized device light may be directed by the second beam combiner to the quarter waveplate. In such embodiments, the quarter waveplate may be configured to convert the p-polarized device light into left-handed circularly polarized device light. Further, in such embodiments, the diffuser may be configured to diffuse the left-handed circularly polarized device light received by the diffuser into right-handed circularly polarized diffused device light. The quarter waveplate may then, in embodiments, be configured to convert the right- handed circularly polarized diffused device light received by the quarter waveplate (back) to linear polarized light, especially to s-polarized diffused device light. However, in embodiments, different polarizations and conversions from the example described here may be possible too, such as e.g. starting from s-polarized device light. Hence, in embodiments, the diffuser assembly may comprise an arrangement of a polarization converter and a diffuser.

[0093] Further, in embodiments, the diffuser may comprise a static diffuser. Alternatively, in embodiments, the diffuser may comprise a dynamic diffuser, such as e.g. a rotating wheel comprising a reflective diffuser track.

[0094] Furthermore, in such embodiments, the diffuser assembly may comprise condensing and collecting (or collimating) optical elements. In embodiments, the condensing and collecting optical elements may be located in an optical path between the collinear reflective diffuser and at least one of the light generating devices (such as e.g. between the diffuser and the polarization converter). In such embodiments, the condensing and collecting (or collimating) optical elements may comprise one or more positive lenses. As it may be advantageous to create a virtual diffused device light source with dimensions that are comparable to the luminescent material light, it may be preferred to apply a set of two, or possibly three positive condenser lenses to enable a large effective numerical aperture just as used in a reflective mode luminescent material configuration. For transmission efficiency as well as survival of the lenses, the induced stresses due to absorption of light may need to be limited. For this, in embodiments, a very low absorption glass with e.g. an internal transmission of at least 99.7% through 10 mm material may be applied. Hence, in embodiments, suitable glass materials may be selected from the group comprising: N-BK7, N-BK7HT, H-K9L, or H-K9LGT. Especially, in embodiments, the condenser and / or collecting optical elements may comprise fused silica (FS).

[0095] As described above, in embodiments, the second beam combiner may be configured downstream of both the luminescent material and the diffuser assembly, and may therefore comprise at least a (first) dichroic beam combiner. Additionally, in embodiments such as described here, the second beam combiner may further comprise a (partially) polarizing beam splitter ((P)PBS). Especially, the second beam combiner may be configured to split the device light (received by the second beam combiner) and the diffused device light (received by the second beam combiner) into a different optical path, based on their respective polarizations. Hence, in embodiments, the second beam combiner may be configured to (at least partially) (i) transmit the (first and / or second, and optionally further device light, such as e.g. blue and / or red) device light received by the second beam combiner and comprising one of the first linear polarization and the second linear polarization and (ii) to reflect the (first and / or second, and optionally further device light, such as e.g. blue and / or red) diffused device light received by the second beam combiner and comprising the other one of the first linear polarization and the second linear polarization in an optical path towards the light exit. Alternatively, in embodiments, the second beam combiner may be configured to (at least partially) (i) reflect the (first and / or second, and optionally further device light, such as e.g. blue and / or red) device light received by the second beam combiner and comprising one of the first linear polarization and the second linear polarization and (ii) to transmit the (first and / or second, and optionally further device light, such as e.g. blue and / or red) diffused device light received by the second beam combiner and comprising the other one of the first linear polarization and the second linear polarization in an optical path towards the light exit.

[0096] The second beam combiner may, in embodiments, be configured to reflect X% and to transmit 1-X% of (diffused) device light comprising (either) the first (or the second) linear polarization. In such embodiments, X may be selected from the range of 0-100%, such as from the range of 20-80%, like from the range of 30-70%.

[0097] Furthermore, in embodiments, the second beam combiner may comprise the polarizing beam splitter with additional spectral requirements relative to the luminescent material. Especially, in embodiments, the luminescent material may have a luminescent material centroid wavelength ( imc). In embodiments, the luminescent material centroid wavelength ( imc) may be selected from the wavelength range of 500-780 nm, such as from the wavelength range of 520-750 nm, like from the wavelength range of 550-700 nm. In such embodiments, the second beam combiner may thus comprise additional spectral requirements to allow luminescent material light received from the luminescent material to propagate via the second beam combiner to the light exit.

[0098] For example, in embodiments (especially where the first linear polarization may be p-polarization), the second beam combiner may be configured to transmit (first and / or second) device light comprising the first linear polarization (e.g. p-polarization in an optical path to the diffuser assembly. In such embodiments, the second beam combiner may further be configured to reflect (first and / or second) device light comprising the second linear polarization (e.g. s-polarization, i.e., different from the first linear polarization) in an optical path to the luminescent material. Further, in such embodiments, the second beam combiner may further be configured to transmit luminescent material light having the luminescent material centroid wavelength ( imc) in an optical path to the light exit. Yet further, in such embodiments, the second beam combiner may be configured to reflect diffused device light (comprising the second linear polarization) in an optical path to the light exit.

[0099] In an alternative example, in embodiments (especially where the first linear polarization may be s-polarization), the second beam combiner may be configured to reflect (first and / or second) device light comprising the first linear polarization (e.g. s-polarization in an optical path to the diffuser assembly. In such embodiments, the second beam combiner may further be configured to transmit (first and / or second) device light comprising the second linear polarization (e.g. p-polarization, i.e., different from the first linear polarization) in an optical path to the luminescent material. Further, in such embodiments, the second beam combiner may further be configured to reflect luminescent material light having the luminescent material centroid wavelength ( imc) in an optical path to the light exit. Yet further, in such embodiments, the second beam combiner may be configured to transmit diffused device light (comprising the second linear polarization) in an optical path to the light exit. Hence, in specific embodiments, the diffuser may be configured in the reflective mode, wherein an optical axis (Oi) of incoming device light and an optical axis (Or) of outgoing diffused device light (i) (relative to the diffuser) may have a parallel direction relative to each other, and (ii) the incoming device light may comprise polarized light; wherein the diffuser assembly may comprise a quarter waveplate configured in an optical path between at least one of the redirection optical elements and the diffuser, wherein the quarter waveplate may be configured to convert linear polarized light received by the quarter waveplate into elliptical polarized light and to convert elliptical polarized light received by the quarter waveplate into linear polarized light; and wherein the second beam combiner may further comprise a (partially) polarizing beam splitter (PBS), wherein the second beam combiner may be configured to (at least partially): (A) (i) transmit (first and / or second) device light comprising a first linear polarization in an optical path to the diffuser assembly, (ii) reflect (first and / or second) device light comprising a second linear polarization in an optical path to the luminescent material, and (iii) transmit luminescent material light having a luminescent material centroid wavelength ( imc) in an optical path to the light exit, wherein the luminescent material centroid wavelength ( imc) may be selected from the wavelength range of 500-780 nm; or (B) (i) reflect (first and / or second) device light comprising a first linear polarization in an optical path to the diffuser assembly, (ii) transmit (first and / or second) device light comprising a second linear polarization in an optical path to the luminescent material, and (iii) reflect luminescent material light having a luminescent material centroid wavelength ( imc) in an optical path to the light exit, wherein the luminescent material centroid wavelength ( imc) is selected from the wavelength range of 500-780 nm.

[0100] As demonstrated here, light may propagate through the light generating system in a variety of different ways depending on the choice of optical components and light characteristics. The above described embodiments provide different varieties of light propagation through the system through the selection of optical properties of the second beam combiner. In embodiments, further varieties of light propagation through the system may be provided through the selection of optical properties of the first beam splitter (as described above), and / or through the use of a third light generating device. Here below, such embodiments are described in further detail.

[0101] In some embodiments, the device light of the first and second light generating devices may both (essentially fully) be provided in an optical path to the luminescent material, such that the optical power provided to the luminescent material may be improved. In such embodiments, the two or more light generating devices may comprise further light generating devices configured to provide device light in an optical path to the diffuser assembly. Especially, in embodiments, the light generating system (especially the two or more light generating devices) may therefore further comprise a third light generating device. The third light generating device may, in embodiments, be configured to generate third device light. Therefore, in embodiments, the third light generating device may comprise a third light source. 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 laser diode, a superluminescent diode, and a stacked multi -junction light-emitting diode (LED). The third light generating device may herein also comprise a plurality of third (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.

[0102] Further, in embodiments, the third light generating device may especially be configured to generate third device light having a third centroid wavelength (Acs). Especially, in embodiments, (at least part of) the third device light may have a third centroid wavelength (Acs) selected from the wavelength range of 400-500 nm, such as from the range of 400-490 nm, like from the range of 430-490 nm. More especially, in embodiments, (at least part of) the third device light may have a third centroid wavelength (Acs) selected from the wavelength range of 440-490 nm, such as from the wavelength range of 450-480 nm, or such as from the wavelength range of 445-460 nm. Hence, in embodiments, (at least part of) the third device light may be blue light.

[0103] In embodiments, the third light generating device may especially be configured to provide third device light in an optical path (via the optics) to the diffuser assembly. The third light generating device may especially provide additional optical power to the light generating system, therewith improving the brightness and flux of the system light.

[0104] Embodiments as described herein may thus provide the benefits of improving brightness, flux, spectral power distribution, and tuneability of the CCT of the system light, as the fraction of device light in the diffuser channel versus the luminescent material channel may be controlled. Therefore, in embodiments, the light generating system may further comprise a control system. The control system may especially be configured to control one or more of a correlated color temperature, a color rendering index, a spectral power distribution, and a radiant flux of the system light. In embodiments, the control system may e.g. control said characteristics of the system light by controlling (the power of) one or more of the light generating devices.

[0105] In specific embodiments, the control system may be configured to control one or more of the spectral power distribution and the radiant flux of the system light, 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 spectral power distribution and the radiant flux of the system light, 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, 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>200 K, like CCT2-CCTl>400 K, like at least 500 K, such as CCT2-CCTl>600 K, especially CCT2- CCTl>800 K. Especially, in embodiments, CCT2-CCTl>1000 K, more especially CCT2- CCTl>1500 K. Further, in embodiments, CCT2-CCT1 may be at most 5000K, such as at most 3000K, like at most 2500K.

[0106] Additionally or alternatively, in embodiments, the control system may e.g. control optical characteristics of the system light by controlling the polarization of device light in the light generating system (e.g. through the use of a polarizing beam splitter as described above).

[0107] In some embodiments, as described above, device light reaching one or more of the redirection optical elements (such as e.g. the first (polarizing) beam splitter) may need to comprise polarized light. Especially, in embodiments, device light reaching one or more of the redirection optical elements (such as e.g. the first (polarizing) beam splitter) may comprise linear polarized light. The term “linear polarized light” (or “linearly polarized light”) may herein refer to light having (electric field) oscillations predominantly aligned in a single plane. Hence, it is not excluded that some oscillations occur outside of the single plane, such as in a plane perpendicular thereto. For instance, in embodiments, the linear polarized light may have at least 80% of (electric field) oscillations in a single plane, such as at least 90%, especially at least 95%, such as at least 99%, including 100%. The linearly polarized light may, in embodiments, also comprise elliptically polarized light with a large ratio of perpendicular polarization components, such as a ratio > 4, especially > 6, such as > 10, especially > 20. As known in the art, linear polarized light may be generated by optical elements of solid state lasers, e.g., desired filters, laser cavity dimensional and / or structural characteristics, and / or intracavity elements. The linear polarizations s-polarized and p- polarized may be considered complementary polarizations (or orthogonal polarizations).

[0108] Furthermore, in such embodiments, the light generating system may further comprise a polarization control system. The polarization control system may, in embodiments be configured to provide, in an optical path to the second beam combiner (and / or to the first beam splitter), an adjustable contribution of (a) (one or more of first, second, third, and further) device light comprising a first linear polarization and (b) (one or more of first, second, third, and further) device light comprising a second linear polarization different from the first linear polarization. Therefore, in embodiments, the polarization control system may comprise one or more of a retarder element (like a retarder plate) and a moving element.

[0109] The retarder element may, in embodiments, be configured in an optical path between the first beam combiner and the second beam combiner. Alternatively, in embodiments, the retarder element may be configured in an optical path between (i) the first light generating device and the first beam combiner or (ii) the second light generating device and the first beam combiner. Yet alternatively, in embodiments, the retarder element may be configured in an optical path between the third light generating device and the first beam splitter. Similarly, in embodiments, the retarder element may be configured in an optical path between the second (or first) light generating device and the first beam splitter. Yet alternatively, in embodiments, the retarder element may be configured in an optical path between the first beam combiner and the first beam splitter. Yet alternatively, in embodiments, the retarder element may be configured in an optical path between the third light generating device and a further redirection optical element (such as a second geometric beam combiner, see also further below). In any case, in embodiments, the retarder element may be configured to dictate the polarization of light propagating from the retarder element. Especially, in embodiments, the retarder element may be configured to change the polarization of device light received by the retarder element in dependence of the orientation of the retarder element. Therefore, in embodiments, the retarder element may comprise one or more of a birefringent rotator such as a X / 2 waveplate or a X / 4 waveplate, a liquid crystal polarization rotator, a Faraday rotator, a Fresnel rhomb, and a diffractive waveplate. Especially, in embodiments, the retarder element may comprise a X / 2 waveplate. However, in embodiments, other types of birefringent rotators (such as e.g. a X / 4 waveplate) may herein not be excluded. Hence, in embodiments, the retarder element may comprise a retarder plate. In embodiments, the control system may be configured to control the polarization control system. As such, in embodiments, the control system may be configured to control rotation of the retarder element. By changing the orientation of the retarder element relative to an optical axis of the device light received by the retarder element, the polarization of said device light may change.

[0110] The moving element may, in embodiments, be configured to (move, especially) rotate the first light generating device and / or the second light generating device, such as especially the first light generating device, or such as especially the second light generating device, or both. Additionally or alternatively, in embodiments, the moving element may be configured to rotate one or more of the other light generating devices. Therefore, in embodiments, the moving element may e.g. comprise an actuator. In embodiments, the control system may be configured to control the polarization control system. As such, in embodiments, the control system may be configured to control (movement, especially) rotation of the light generating device(s) by controlling the moving element. By changing the orientation of the light generating devices relative to downstream configured optics (such as e.g. the first beam splitter), the polarization of said device light propagating to the receiving optics (such as propagating to the first beam splitter) may change.

[0111] Note that, in embodiments, the orientations of the retarder element and / or the light generating devices as described above may also be factory set and fixated by a fixating means (such as e.g. a screw). Hence, in specific embodiments, the light generating system may further comprise further a polarization control system, wherein the polarization control system may be configured to provide, in an optical path to the second beam combiner, an adjustable contribution of (a) device light comprising a first linear polarization and (b) device light comprising a second linear polarization different from the first linear polarization; wherein the polarization control system may comprise one or more of (A) a retarder element configured to control a polarization of device light received by the retarder element, wherein the control system may be configured to control rotation of the retarder element; and (B) a moving element configured to move one or more of the first light generating device, the second light generating device, and the first beam combiner, wherein the control system may be configured to control the moving element.

[0112] 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.

[0113] 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.

[0114] 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.

[0115] 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.

[0116] 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).

[0117] 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.

[0118] 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.

[0119] In any case, in embodiments, the light generating system may comprise optics configured such that the diffused device light and the luminescent material light may be provided to the light exit. The term “optics” may especially refer to (one or more) optical elements. Hence, the terms “optics” and “optical elements” may refer to the same items. The optics may 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. See further above for examples of optics. In embodiments, the optics may comprise an integrator, like a “Koehler integrator” (or “Kohler integrator”).

[0120] Further, in embodiments, as the system light may thus comprise a combination of diffused device light and luminescent material light, it may be desired to integrate (or angularly re-distribute) the different types of light, such that homogeneity of the system light may be improved. Therefore, in embodiments, the light generating system may further comprise a(t least one) optical integrator. Especially, in embodiments, the optics may comprise one or more optical integrators. Herein, an optical integrator may refer to an optical element configured to homogenize light received by the optical integrator (, i.e., to provide a more uniform beam of light than the beam of light that was incident on the optical integrator). The optical integrator may herein especially be configured transmissive for the device light. Additionally, in embodiments, the optical integrator may further be configured transmissive for the luminescent material light.

[0121] In embodiments, the one or more optical integrators may comprise a material (individually) selected from the group comprising: a glass material (having a high transmission in the device light spectral range), a silicone-based material, a transparent ceramic material (such as e.g. sapphire), and a polymeric material. For example, in embodiments, the optical integrator may comprise (etched) fused silica. In another example, in embodiments, the optical integrator may comprise a(n engineered) substrate comprising a sol-gel coating. Especially, in embodiments, the optical integrators may be individually selected from the group comprising: a small-angle diffuser, a transmissive volume diffuser, a transmissive surface diffuser, a reflective surface diffuser, a transmissive or reflective diffractive optical element, an engineered diffuser (such as a flat-top, or top-hat diffuser), a gaussian(-like) diffuser, a transmissive holographic optical element, a single multi lens array, a double multi lens array such as a fly-eye lens array pair, and an integrating polygonal light pipe.

[0122] In embodiments, at least one optical integrator may be configured in an optical path between (at least one of) the two or more light generating devices and the diffuser (assembly). In embodiments, at least one optical integrator may thus be configured downstream of (at least one of) the two or more light generating devices and upstream of the diffuser (assembly). Hence, in such embodiments, the transmissive integrator element may be configured in a light-receiving relationship with (at least one of) the two or more light generating devices. The optical integrator may especially be configured to (transmit and) angularly re-distribute the device light received by the optical integrator, such that a smallangle redistributed beam comprising the device light may be provided. In embodiments, the optical integrator may be configured to provide a small-angle redistributed beam comprising the device light (received by the optical integrator) in an optical path to the diffuser (assembly). In turn, the diffuser (assembly)may thus be configured in a light-receiving relationship with the optical integrator. Such embodiments may be beneficial as the optical integrator may allow control of the size of the beam of light propagating from the optical integrator through the system. Furthermore, the optical integrator may provide a more uniformly distributed beam of light propagating from the optical integrator through the system, which may improve efficiency of the light generating system. As the device light emitted from the light generating devices (e.g. laser banks) may, in embodiments, comprise multiple narrow laser beams, each of said individual laser beam may represent a hot spot in the beam of device light. Focusing of such a beam of device light on e.g. a luminescent converter may exceed the maximum tolerable local irradiance and may result in damage to the luminescent material. Therefore, some homogenizing optics may be applied for each beam of device light to remove or reduce the hot spots. Hence, angular re-distribution of light such as described above may not only be beneficial to the diffuser assembly, but also to the conversion channel (i.e. luminescent material pathway) of the light generating system. Therefore, in embodiments, the light generating system may (also) comprise an optical integrator configured in an optical path between (at least one of) the two or more light generating devices and the luminescent material. For example, in embodiments, the optical integrator may be configured between the first light generating device and the redirection optical elements. In another example, the optical integrator may be configured between the redirection optical elements and the luminescent material. In some embodiments, the optical integrator of the diffuser assembly and the optical integrator of the converter channel may be essentially the same optical integrator. However, in other embodiments, the optical integrator of the diffuser assembly and the optical integrator of the converter channel may be separate (or distinct) optical components.

[0123] Furthermore, in embodiments, the light generating system may comprise additional optical integrators. For example, in embodiments, the light generating system may comprise an optical integrator configured downstream of both the diffuser assembly and the luminescent material and upstream of the light exit. Hence, in such embodiments, the optical integrator may be configured to integrate (or angularly and / or spatially re-distribute) the diffused device light and the luminescent material light received by the optical integrator into homogenized system light.

[0124] In embodiments, the (one or more) optical integrator(s) may comprise a smallangle diffuser. Small-angle diffusers may have a dual functionality: a) define a spot diameter of light incident on the e.g. the reflective diffuser or the luminescent material, and b) reduce hot spots in the projected spot on e.g. the reflective diffuser or the luminescent material. Especially, in embodiments, the optical integrator may (comprise a small angle diffuser that may) be configured to re-distribute incoming (device) light such that the light may have a controlled (angular and / or spatial) re-distribution. Especially, in embodiments, the smallangle diffuser may be configured to re-distribute incoming (device) light such that the light may have a FWHM selected from the range of 1-50°, such as from the range of 2-40°, like from the range of 3-30°, especially from the range of 5-20°. In embodiments, the optical integrator may thus comprise a small angle diffuser configured to re-distribute incoming device light, such that device light propagating from the optical integrator may have a FWHM selected from the range of 1-50°. Similarly, in embodiments, other transmissive integrator elements comprised by the light generating system may comprise small-angle diffusers as described here.

[0125] Furthermore, in embodiments, the optical integrator may comprise a top-hat diffuser. Especially, in such embodiments, the top-hat diffuser may be configured to provide an angular distribution (of light) with a half-width-half-maximum (HWHM) selected from the range of 1-15°, such as from the range of 1-10°, like from the range of 2-8°, such as from the range of 3-6°, like e.g. a HWHM of 5°.

[0126] In some applications, it may be desired to provide a light generating system that may be set to a variety of different CCTs. Therefore, in embodiments, the light generating system may further comprise a red light contribution to the system light.

[0127] Therefore, in embodiments, the light generating system (especially the two or more light generating devices) may comprise a fourth light generating device. The fourth light generating device may, in embodiments, be configured to generate fourth device light. Therefore, in embodiments, the fourth light generating device may comprise a fourth light source. The fourth light source may be essentially any light source, see also further below. Especially, in embodiments, the (fourth light source of the) fourth light generating device may comprise a fourth solid state light source. Hence, in embodiments, the fourth light generating device may comprise one or more of a laser diode, a superluminescent diode, and a stacked multi -junction light-emitting diode (LED). The fourth light generating device may herein also comprise a plurality of fourth (solid state) light sources. Especially, in specific embodiments, the fourth light generating device may comprise a fourth laser bank comprising a plurality of fourth lasers.

[0128] Further, in embodiments, the fourth light generating device may especially be configured to generate fourth device light having a fourth centroid wavelength (X^). Especially, in embodiments, (at least part of) the fourth device light may have a fourth centroid wavelength (X^) selected from the wavelength range of 600-780 nm, such as from the range of 600-750 nm, like from the range of 620-700 nm. Hence, in embodiments, (at least part of) the fourth device light may be red light. Thanks to the addition of a red light generating device, the luminescent material may be chosen to have a luminescent color point that results in a suitable “phosphor load line” connecting the color points of the device light and the luminescent light in the output (white or colored) light to achieve improved color rendering and / or improved luminescent conversion (e.g. minimization of droop) and / or improved gamut area (e.g. using lower wavelength luminescent green emission). As a consequence, a largely improved range of CCT values may be achieved, and even a large range of color points that are all located on the black body locus (BBL) may be realized.

[0129] The fourth light generating device may, in embodiments, be configured to provide fourth device light (optionally via the optics) to the diffuser assembly. Especially, in embodiments, the one or more redirection optical elements (such as e.g. a dichroic or geometric beam redirector) may be configured to combine the fourth device light into a same optical path with (at least the first and second) diffused device light to the diffuser assembly. In some embodiments, for example, the redirection optical elements may comprise a third beam combiner configured to redirect (e.g. combine) blue (first, second, third, and / or further device light) and red (fourth) device light received by the third beam combiner into a same optical path to the diffuser assembly. In such embodiments, the third beam combiner may especially comprise a second dichroic beam combiner. Especially, in some embodiments, the third beam combiner may be configured to transmit light having a wavelength below a cutoff wavelength (e.g. transmit blue device light) and to reflect light having a wavelength above a cut-off wavelength (e.g. reflect red device light). In other embodiments, the third beam combiner may be configured to reflect light having a wavelength below a cut-off wavelength (e.g. reflect blue device light) and to transmit light having a wavelength above a cut-off wavelength (e.g. transmit red device light). Hence, in embodiments, the fourth device light may be provided to the diffuser assembly (optionally via the third beam combiner). Hence, as such, the diffuser assembly may be configured in a light-receiving relationship (optionally via the optics) with the fourth light generating device.

[0130] In embodiments, the diffuser assembly may thus be configured to diffuse not only blue device light, but also red device light. Especially, in embodiments, the diffuser assembly may be configured to provide diffused device light as described above but comprising both (diffused) first and / or second (and optionally third or even fifth) device light and (diffused) fourth device light.

[0131] During operation, in embodiments, different types of light (especially comprising different wavelengths) may therefore propagate through the light generating system. As described above, the redirection optical elements may be configured to redirect the different types of light e.g. based on polarization, wavelength, and spatial orientation. Especially, in embodiments, the first beam splitter may be configured to provide polarization- based redistribution of device light over the conversion channel and the diffusion channel. Furthermore, in embodiments, the first beam splitter may also be configured to provide dichroic separation of the optical paths of at least two spectrally different types of light, one of which comprising (at least) device light and the other of which comprising (at least) luminescent material light. Yet further, in embodiments, the first beam splitter may also be configured to provide dichroic separation and / or combination of the optical paths of at least two spectrally different types of device light, one of which comprising blue (e.g. one or more of the first, second, third, and fifth) device light and the other of which comprising red (e.g. the fourth) device light. Therefore, in embodiments, the first beam splitter may comprise a polarizing beam splitter with additional spectral requirements (and may therefore be indicated with PBS,DBC). Such embodiments may e.g. be enabled in an integrated component comprising different dielectric layers (e.g. comprising separate dielectric layers configured in or on a substrate or comprising a single integrated layer (comprising a stack of dielectric layers) configured in or on a substrate). For example, in embodiments, the first beam splitter (e.g. an integrated component with the second beam combiner) may split the incident (blue) device light over optical paths to the luminescent material and the diffuser, and may further be configured to (re-)direct the luminescent material light (i.e., may be configured transmissive or reflective for luminescent material light). Additionally, in such embodiments, the first beam splitter may also be configured to combine the luminescent material light and the diffused device light into a same optical path to the light exit. Hence, in such embodiments, the first beam splitter may be configured to transmit diffused device light received by the first beam splitter and to reflect luminescent material light received by the first beam splitter. Alternatively, in such embodiments, the first beam splitter may be configured to reflect diffused device light received by the first beam splitter and to transmit luminescent material light received by the first beam splitter. In embodiments, the first beam splitter may thus also have some dichroic beam combining properties (e.g. comprising a combination of a low-pass filter with a polarizing beam splitter).

[0132] In an operational mode of the light generating system, in embodiments, the light generating system may therefore be configured to generate white system light comprising at least part of the luminescent material light and at least part of the diffused device light. Hence, in specific embodiments, the two or more light generating devices may comprise a fourth light generating device configured to generate fourth device light having a fourth centroid wavelength (X^), wherein (for at least part of) the fourth device light) the fourth centroid wavelength (X^) may be selected from the wavelength range of 600-780 nm; wherein the redirection optical elements may be configured to direct the fourth device light in an optical path to the diffuser assembly; wherein the diffuser may be configured to diffuse at least part of the device light, comprising fourth device light and one or more of first device light and second device light, received by the diffuser, into diffused device light.

[0133] In embodiments, instead of the third beam combiner, a fourth beam combiner may be configured to redirect the (red) fourth device light received by the fourth beam combiner into a same optical path to the diffuser assembly. Hence, in embodiments, the redirection optical elements may comprise a fourth beam combiner. Especially, in such embodiments, the fourth beam combiner may comprise a second geometric beam combiner. The second geometric beam combiner may be a similar geometric beam combiner as described above. Especially, in embodiments, the second geometric beam combiner (GBC2) may comprise a plate comprising geometric-optical features that may correlate to a geometrical distribution of light sources configured to provide light to the second geometric beam combiner. As such, in embodiments, light from part of the light sources (configured to provide light to the GBC2) may be reflected by the second geometric beam combiner, whereas light from another part of the light sources (configured to provide light to the GBC2 at a different location on the GBC2 than the previous part) may be transmitted by the second geometric beam combiner. Such reflection or transmission of the light may, in embodiments, depend on the geometric-optical design of the geometric beam combiner. Furthermore, in embodiments, at least part of the fourth beam combiner may comprise a light transmissive, especially a light transparent, material. Especially, at least part of the first beam combiner may thus comprise a light (transmissive, especially a light) transparent material. For example, in embodiments, at least part of the first beam combiner may comprise a material selected from the group comprising: a glass material, a polymeric material, and a ceramic material.

[0134] Especially, in embodiments, the light generating system may comprise a third light generating device comprising a single third laser and a fourth light generating device comprising a single fourth laser. In such embodiments, the third laser and the fourth laser may be configured to provide third and fourth device light, respectively, to the fourth beam combiner (i.e. the second GBC2) such that the third and fourth device light may be incident on different (spatial) locations of the second geometric beam combiner. Especially, in such embodiments, the third laser and the fourth laser may be configured to provide third and fourth device light, respectively, to the fourth beam combiner (i.e. the second GBC2) from orthogonal directions (i.e. an optical axis of the third device light and an optical axis of the fourth device light incident on the second GBC2 may be orthogonal relative to each other). The fourth beam combiner (i.e. the second GBC2) may, in such embodiments, be configured to (i) reflect one of the third device light and the fourth device light and to (ii) transmit the other one of the third device light and the fourth device light, such that the third device light and fourth device light may be combined into the same optical path (propagating from the fourth beam combiner).

[0135] Note that, in embodiments, the third device light received by the fourth beam combiner may not necessarily propagate all the way to the diffuser assembly. For example, in embodiments, the first beam splitter may be configured in an optical path between the fourth beam combiner and both the luminescent material and the diffuser assembly. In such embodiments, the first beam splitter may be configured in a light-receiving relationship with the fourth beam combiner (i.e. may be configured to receive both the third and fourth device light). However, in such embodiments, the first beam splitter may be configured to transmit or reflect (essentially all of) the third device light to the luminescent material and to reflect or transmit (essentially all of) the fourth device light to the diffuser assembly (i.e. the first beam splitter may comprise a dichroic (or wavelength-)based redirection optical element. Such embodiments may especially be applicable when, e.g., the first light generating device and / or the second light generating device are configured to provide (blue) device light to the diffuser assembly, such that the desired blue power in the system light may be provided (without needing to diffuse the third device light as well).

[0136] Hence, in specific embodiments, the two or more light generating devices may comprise the third light generating device and the fourth light generating device, wherein the redirection optical elements may comprise a fourth beam combiner, wherein the fourth beam combiner may be configured to direct third device light received by the fourth beam combiner and fourth device light received by the fourth beam combiner in an optical path to the diffuser assembly, optionally a first (polarizing) beam splitter; and wherein the fourth beam combiner may comprise a second geometric beam combiner (GBC2) comprising a plate comprising geometric-optical features that correlate to a geometrical configuration of the third light generating device and the fourth light generating device.

[0137] Yet further, in embodiments, the light generating system (especially the two or more light generating devices) may comprise a fifth light generating device. The fifth light generating device may, in embodiments, be configured to generate fifth device light. Therefore, in embodiments, the fifth light generating device may comprise a fifth light source. The fifth light source may be essentially any light source, see also further below. Especially, in embodiments, the (fifth light source of the) fifth light generating device may comprise a fifth solid state light source. Hence, in embodiments, the fifth light generating device may comprise one or more of a laser diode, a superluminescent diode, and a stacked multi -junction light-emitting diode (LED). The fifth light generating device may herein also comprise a plurality of fifth (solid state) light sources. Especially, in specific embodiments, the fifth light generating device may comprise a fifth laser bank comprising a plurality of fifth lasers.

[0138] Further, in embodiments, the fifth light generating device may especially be configured to generate fifth device light having a fifth centroid wavelength (Acs). Especially, in embodiments, (at least part of) the fifth device light may have a fifth centroid wavelength (Acs) selected from the wavelength range of 400-500 nm, such as from the range of 400-490 nm, like from the range of 430-490 nm. More especially, in embodiments, (at least part of) the fifth device light may have a fifth centroid wavelength (Acs) selected from the wavelength range of 440-490 nm, such as from the wavelength range of 450-480 nm, or such as from the wavelength range of 445-460 nm. Hence, in embodiments, (at least part of) the fifth device light may be blue light.

[0139] In embodiments, the fifth light generating device may especially be configured to provide fifth device light in an optical path (via the optics) to the luminescent material. The fifth light generating device may especially provide additional optical power to the light generating system, therewith improving the brightness and flux of the system light.

[0140] As described herein, the light generating system may thus comprise two or more light generating devices, such as two or more of the first light generating device, the second light generating device, the third light generating device, the fourth light generating device, and the fifth light generating device. In specific embodiments, at least one of the two or more light generating devices may comprise a bi-color light generating device. Herein, a bi-color light generating device may refer to a light generating device comprising at least two light sources (preferably laser) emitting at substantially different characteristic wavelengths. For example, in embodiments, at least one of the two or more light generating devices may comprise a laser bank comprising a first subset of lasers and a second subset of lasers. In such embodiments, the first subset of lasers may be configured to provide light source light (especially laser light) having a (primary) centroid wavelength selected from the blue wavelength range (e.g. 430-490 nm), whereas the second subset of lasers may be configured to provide light source light (especially laser light) having a (secondary) centroid wavelength selected from the red wavelength range (e.g. 600-780 nm). Hence, in embodiments, at least one of the two or more light generating devices may comprise at least two types of solid state light sources having different peak wavelengths. Especially, in such embodiments, their respective peak wavelengths may differ by at least 5 nm, such as at least 10 nm, like at least 20 nm, especially at least 50 nm.

[0141] For example, in embodiments, the first light generating device may comprise a plurality of (solid state) light sources (e.g. lasers) configured to provide light source light having the same peak wavelength in the blue wavelength range. In such embodiments, the first device light may have the first centroid wavelength (Xci) selected from the wavelength range of 430-490 nm. Alternatively, in embodiments, the first light generating device may comprise a plurality of (solid state) light sources (e.g. lasers), wherein a first subset may be configured to provide light source light having a (primary) first centroid wavelength (Xci) in the blue wavelength range, whereas a second subset may have a (secondary) first centroid wavelength (Xci) in the red wavelength range. In such embodiments, at least part of the first device light (especially the first device light provided by the first subset of light sources) may have a primary first centroid wavelength (Xci) selected from the wavelength range of 430-490 nm, whereas the other part of the device light (especially the first device light provided by the second subset of light sources) may have a secondary first centroid wavelength (Xci) selected from the wavelength range of 600-780 nm. Similar embodiments may also apply for the other (e.g. the second, third, fourth, and / or fifth) light generating devices. Furthermore, in such embodiments, the first subset of (solid state) light sources (e.g. lasers) and the second subset of (solid state) light sources (e.g. lasers) may be individually controllable. For example, in embodiments, the first subset of (solid state) light sources may be operating while the second subset of (solid state) light sources may be turned off, or vice versa.

[0142] 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.

[0143] 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. 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.

[0144] As indicated above, the light generating system comprises a light generating device. A light generating device may especially be configured to generate device light. Especially, the light generating device may comprise a light source. The light source may especially configured to generate light source 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.

[0145] The term “light source” may in principle relate to any light source known in the art. The term “light source” may also relate to a plurality of light sources, such as 2-2000 (solid state) LED light sources.

[0146] The light source may have a light escape surface. 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.

[0147] 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.

[0148] 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. 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. In embodiments, the light source may comprise one or more micro-optical elements (array of micro lenses) downstream of a single solid-state light source, such as an LED, or downstream of a plurality of solid-state light sources (i.e. e.g. shared by multiple LEDs). In embodiments, the light source may comprise an LED with on-chip optics. In embodiments, the light source comprises pixelated single LEDs (with or without optics) (offering in embodiments on-chip beam steering).

[0149] 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.

[0150] In other embodiments, however, the light source may be configured to provide primary radiation and part of the primary radiation is converted into secondary radiation. Secondary radiation may be based on conversion by a luminescent material. The secondary radiation may therefore also be indicated as luminescent material radiation.

[0151] 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.

[0152] 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.

[0153] 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).

[0154] The term “light source” herein may also refer to a light source comprising a solid state light source, such as an LED or a laser diode or a superluminescent diode.

[0155] 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. Hence, the term “light source” may also refer to a combination of an LED with a luminescent material configured to convert at least part of the LED radiation, or to a combination of a (diode) laser with a luminescent material configured to convert at least part of the (diode) laser radiation.

[0156] 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.

[0157] 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.

[0158] The term “solid state light source”, or “solid state material light source”, and similar terms, may especially refer to semiconductor light sources, such as a light emitting diode (LED), a diode laser, or a superluminescent diode.

[0159] 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.

[0160] 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 (CrZnSe) 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, trival ent 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.

[0161] 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.

[0162] 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.

[0163] A laser may be combined with an upconverter in order to arrive at shorter (laser) wavelengths. For instance, with some (trival ent) rare earth ions upconversion may be obtained or with non-linear crystals upconversion can be obtained. Alternatively, a laser can be combined with a downconverter, such as a dye laser, to arrive at longer (laser) wavelengths.

[0164] 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.

[0165] The laser light source is configured to generate laser light source light (or “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. For instance, the laser light source light of two or more (different or identical) laser light sources may be coupled into a light guide, to provide a single beam of light comprising the laser light source light of the two or more (different or identical) laser light sources. In specific embodiments, the light source light is thus especially collimated light source light. In yet further embodiments, the light source light is especially (collimated) laser light source light.

[0166] 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.

[0167] 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). 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.

[0168] The term “solid state light source”, and similar terms, may especially refer to semiconductor light sources, such as a light emitting diode (LED), a laser diode, or a superluminescent diode.

[0169] Instead of the term “solid state light source” also the term “semiconductorbased light source” may be applied. Hence, the term “semiconductor-based light source” may e.g. refer to one or more of a light emitting diode (LED), a laser diode, and a superluminescent diode. Hence, the light generating device may comprise one or more of a light emitting diode (LED), a laser diode, and a superluminescent diode.

[0170] 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.

[0171] A laser diode (or diode laser) may be a semiconductor device substantially similar to a light-emitting diode in which a diode pumped directly with electrical current can create lasing conditions at the diode's junction. This is known to a person skilled in the art.

[0172] 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. Especially, a superluminescent diode may be a semiconductor light source, where the spontaneous emission light is amplified by stimulated emission in the active region of the device. Such emission is called “super luminescence”. Superluminescent diodes combine the high power and brightness of laser diodes with the low coherence of conventional lightemitting 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. 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. Hence, in embodiments, the solid state light source may comprise a superluminescent diode. 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.

[0173] 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. 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 stage lighting device, an (entertainment) moving head lighting device, a spot light, a search light, 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 luminescent material, the diffuser assembly, and the optics.

[0174] 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.

[0175] 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).

[0176] 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). The term “centroid wavelength”, also indicated as c, 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 Ze = X A* 1(A) / (S I( 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.

[0177] BRIEF DESCRIPTION OF THE DRAWINGS

[0178] 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:

[0179] Figs. 1-8 schematically depict some embodiments of the light generating system.

[0180] Fig. 9 further schematically depicts some aspects of the invention.

[0181] Fig. 10 schematically depicts some applications of the light generating system in lighting devices.

[0182] The schematic drawings are not necessarily to scale.

[0183] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0184] Figs. 1 schematically depicts a light generating system 1000 comprising two or more light generating devices 100, a luminescent material 200, a diffuser assembly 700, optics 500, and a light exit 1090.

[0185] In embodiments, the two or more light generating devices 100 may be configured to generate device light 101. Especially, the light generating devices 100 may comprise solid state light sources 10,20 individually selected from the group comprising laser diodes, superluminescent diodes, and stacked multi -junction light-emitting diodes. In further embodiments, the two or more light generating devices 100 may comprise (i) a first light generating device 110 configured to generate first device light 111 and (ii) a second light generating device 120 configured to generate second device light 121. In embodiments, the first device light 111 may have a first centroid wavelength (Xci). Especially, in embodiments, the first centroid wavelength (Xci) may be selected from the wavelength range of 430-490 nm. Similarly, in embodiments, the second device light 121 may have a second centroid wavelength (X^). Especially, in embodiments, the second centroid wavelength (^2) may be selected from the wavelength range of 430-490 nm.

[0186] Further, in embodiments, in embodiments, the first light generating device 110 may comprise a first laser bank 1111. Especially, the first laser bank 1111 may comprise a first array 1110 (see Fig. 9) comprising a plurality of first solid state light sources 10. In embodiments, the first solid state light sources 10 may comprise first lasers 1010. Similarly, in embodiments, the second light generating device 120 may comprise a second laser bank 2222. In further embodiments, the second laser bank 2222 may comprise a second array 2110 (see Fig. 9) comprising a plurality of second solid state light sources 20. Especially, the second solid state light sources 20 may comprise second lasers 2010. However, in alternative embodiments, at least one of the two or more light generating devices 100 may comprise at least two types of solid state light sources 10,20. . . having different centroid wavelengths. For example, in embodiments, the first light generating device 111 (especially first laser bank 1111) may comprise a first array 1110 (see Fig. 9) comprising a plurality of first solid state light sources 10 configured to generate blue light source light (such as having a wavelength selected from 430-490 nm) and a plurality of third solid state light sources 30 configured to generate red light source light (such as having a wavelength selected from 600-780 nm). Especially, in embodiments, their respective centroid wavelengths may differ by at least 10 nm. Hence, in such embodiments, the first device light may have a centroid wavelength comprising a weighted average of a centroid wavelength of the plurality of first solid state light sources 10 and a centroid wavelength of the plurality of third solid state light sources 30.

[0187] Furthermore, in embodiments, the optics 500 may comprise redirection optical elements 1500. In embodiments, the redirection optical elements 1500 may comprise a first beam combiner 1510 and a second beam combiner 1520. The first beam combiner 1510 may, in embodiments, be configured to direct first device light 111 received by the first beam combiner 1510 and second device light 121 received by the first beam combiner 1510 in an optical path to another one of the redirection optical elements 1500. For example, as depicted here in Fig. 1, the first beam combiner 1510 may be configured to direct first device light 111 received by the first beam combiner 1510 and second device light 121 received by the first beam combiner 1510 in an optical path to the second beam combiner 1520. Alternative examples are illustrated further below.

[0188] In embodiments, the first beam combiner 1510 may comprise a geometric beam combiner GBC1. Especially, in embodiments, the geometric beam combiner GBC1 may comprise a plate comprising geometric-optical features 1513 that correlate to a geometrical (configuration or especially geometrical) distribution of the plurality of first solid state light sources 10 and the plurality of second solid state light sources 20.

[0189] The optics 500 may, in embodiments, be configured to direct, in a first operational mode of the light generating system 1000, a part of the device light 101 comprising one or more of first device light 111 and second device light 121, in an optical path to the luminescent material 200 via the first beam combiner 1510 and the other one of the redirection optical elements 1500. Additionally, in embodiments, the optics 500 may be configured to direct, in the first operational mode of the light generating system 1000, a part of the device light 101 in an optical path to the diffuser assembly 700.

[0190] In embodiments, the luminescent material 200 may be configured to convert at least part of first device light 111 received by the luminescent material 200 and at least part of second device light 121 received by the luminescent material 200 into luminescent material light 201.

[0191] Moreover, in embodiments, the diffuser assembly 700 may comprise a diffuser 710. In embodiments, the diffuser 710 may be configured to diffuse at least part of the device light 101 (comprising one or more of first device light 111, second device light 121, and third device light 131, see also further below) received by the diffuser 710 into diffused device light 711.

[0192] Further, in embodiments, the second beam combiner 1520 may be configured to direct luminescent material light 201 received by the second beam combiner 1520 and diffused device light 711 received by the second beam combiner 1520 in an optical path towards the light exit 1090. Especially, the second beam combiner 1520 may comprise a dichroic beam combiner DBC.

[0193] Hence, in embodiments, the light generating system 1000 may be configured to generate, in the first operational mode of the light generating system 1000, system light 1001 comprising at least part of the diffused device light 701 and at least part of the luminescent material light 201. Especially, in embodiments, the system light 1001 may be white light having a correlated color temperature selected from the range of 2000-12000 K and a color rendering index of at least 65.

[0194] In 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 and the radiant flux of the system light 1001. Further, in embodiments, the light generating system 1000 may comprise a polarization control system 600. In embodiments, the polarization control system 600 may be configured to provide, in an optical path to the second beam combiner 1520 (and / or to the first beam splitter 1505), an adjustable contribution of (a) device light 101 comprising a first linear polarization and (b) device light 101 comprising a second linear polarization different from the first linear polarization. Therefore, in embodiments, the polarization control system 600 may comprise a retarder element 610 configured to control a polarization of device light 101 received by the retarder element 610. The retarder element 610 may especially be configured downstream of at least one of the light generating devices 100 and upstream of the second beam combiner (and / or upstream of the first beam splitter 1505). For example, in embodiments, the retarder element 610 may comprise e.g. a (X / 2) waveplate or a Faraday rotator. Furthermore, in embodiments, the control system 300 may be configured to control rotation of the retarder element 610. Additionally or alternatively, in embodiments, the polarization control system 600 may comprise a moving element 620 configured to move (such as especially rotate) one or more of the first light generating device 110, the second light generating device 120, (the third light generating device 130,) and the first beam combiner 1510. Furthermore, in embodiments, the control system 300 may be configured to control the moving element 620.

[0195] Yet further, in some embodiments, the redirection optical elements 1500 may comprise a first beam splitter 1505 configured to direct at least part of the device light 101 received by the first beam splitter 1505 in an optical path to the diffuser assembly 700 and to direct at least another part of the device light 101 received by the first beam splitter 1505 in an optical path to the luminescent material 200. Hence, in embodiments, the diffuser assembly 700 may be configured in a light-receiving relationship with the first beam splitter 1505. As depicted here in Fig. 1, in embodiments, the first beam splitter 1505 may be configured together with the second beam combiner 1520 (e.g. as two separate components, or as an integrated component comprising different dielectric layers). In this embodiment, the first beam splitter 1505 may be configured to direct at least part of the first and second device light 111,121 received by the first beam splitter 1505 in an optical path to the diffuser assembly 700 and to direct at least another part of the first and second device light 111,121 received by the first beam splitter 1505 in an optical path to the luminescent material 200.

[0196] Fig. 1 thus schematically depicts a first basic configuration of the light generating system 1000 comprising only a single geometric beam combiner GBC1 (i.e. the first beam combiner 1510) and a single polarizing beam splitter PBS (i.e., the second beam combiner 1520, which may especially comprise the first (polarizing) beam splitter 1505) with additional spectral requirements, therefore in the figure indicated as PBS,DBC, as beam splitting / combining components. In this configuration, the (typically blue) light from the first light generating device 110 and the second light generating device 120 may be combined via the GBC1 while both the first device light 111 and the second device light 121 may have the same (linear) polarization. The combined beam comprising the first device light 111 and the second device light 121 may be directed via an optical integrator 570 and a retarder element 610 (here a birefringent rotator) to the second beam combiner 1520 (here especially a polarizing beam splitter PBS) that redistributes the device light 101,111,121 over a luminescent conversion channel (i.e. in an optical path to the luminescent material 200) and a diffusion channel (i.e. in an optical path to diffuser 710). In particular, the PBS may split the incident (blue) device light 101,111,121 over the luminescent material 200 and the diffuser 710, and needs to be transmissive for luminescent light 201. The PBS subsequently may also combine the luminescent material light 201 and the diffused device light 711 and may direct the thus generated system light 1001 to the light exit 1090. The ratio of the redistribution over the two channels may be determined by the orientation of the retarder element 610, which may in turn be controlled by the control system 300. The device light 101,111,121 directed into the luminescent conversion channel may be condensed onto the luminescent material 200 which may be configured to operate in a reflective mode. The luminescent material light 201 may be separated from the incident device light 101,111,121 path via the PBS, which may thus also have some dichroic beam combining properties (e.g. a high-pass PBS component, transmitting luminescent material light 201, hence the indication PBS,DBC in the figure), and projected to the light exit 1090. The device light 101,111,121 directed into the diffusion channel may pass through a quarter wave plate 720 (QWP or X / 4 plate) which may turn the linear polarization into circular polarization and may subsequently condense and project the circularly polarized device light 101,111,121 onto the diffuser 710 (here configured to operate in a reflective mode). The reflectively diffused device light 711 may be collected and collimated by the same lenses 560 that condensed the device light 101,111,121 onto the diffuser 710. After again passing through the quarter wave plate 720, the circularly polarized diffused device light 711 may be transformed into linearly polarized diffused device light 711, but this time with the polarization direction orthogonal to that of the device light 101,111,121 that exited from the PBS. To enable this, the reflective diffuser 710 may have substantially polarization maintaining diffusion properties. The PBS may then split the reflectively diffused device light 711 from the optical path of the device light 101,111,121 and may project the diffused device light 711 to the light exit 1090. Hence, the PBS may thereby combine the luminescent light 201 and the reflectively-diffused device light 711 into combined (white) system light 1001.

[0197] As described above, in embodiments, the optics 500 may thus comprise one or more optical integrators 570. The optical integrators may be configured to reduce hot spots in the light received by the optical integrators 570. Therefore, in embodiments, at least one optical integrator 570 may be configured in an optical path between (at least one of) the two or more light generating devices 100 and the luminescent material 200. Additionally, in embodiments, at least one optical integrator 570 may be configured in an optical path between (at least one of) the two or more light generating devices 100 and the diffuser assembly 700. As depicted in Fig. 1, in embodiments, a single optical integrator 570 may be configured between (i) the two or more light generating devices 100 and (ii) both the luminescent material 200 and the diffuser assembly 700. Yet additionally, in embodiments, at least one optical integrator 570 may be configured in an optical path between the redirection optical elements 1500 and the light exit 1090.

[0198] Reference 1250 may further refer to a (support, such as especially a) heat sink. Furthermore, as described above, the diffuser 710 may be configured in the reflective mode. Moreover, in embodiments as depicted here, an optical axis Oi of incoming device light 101 and an optical axis Orof outgoing diffused device light 711 (relative to the diffuser 710) may have a parallel direction relative to each other. Furthermore, in such embodiments, the incoming device light 101 may comprise polarized light. Moreover, in such embodiments, the diffuser assembly 700 may comprise a quarter waveplate 720 configured in an optical path between (i) at least one of the redirection optical elements 1500 and (ii) the diffuser 710. Especially, the quarter waveplate 720 may be configured to convert linear polarized light received by the quarter waveplate 720 into elliptical polarized light and to convert elliptical polarized light received by the quarter waveplate 720 into linear polarized light. Moreover, in such embodiments, the second beam combiner 1520 may further comprise a (partially) polarizing beam splitter (PBS).

[0199] Especially, in embodiments, the second beam combiner 1520 may be configured to (at least partially) transmit (first and / or second) device light 101 comprising a first linear polarization in an optical path to the diffuser assembly 700. Additionally, in such embodiments, the second beam combiner 1520 may be configured to (at least partially) reflect (first and / or second) device light 101 comprising a second linear polarization in an optical path to the luminescent material 200. Yet additionally, in such embodiments, the second beam combiner 1520 may be configured to (at least partially) transmit luminescent material light 201 having a luminescent material centroid wavelength ( imc) in an optical path to the light exit 1090. Especially, the luminescent material centroid wavelength ( imc) may be selected from the wavelength range of 500-780 nm.

[0200] Alternatively, in embodiments, reflect (first and / or second) device light 101 comprising a first linear polarization in an optical path to the diffuser assembly 700. Additionally, in such embodiments, the second beam combiner 1520 may be configured to (at least partially) transmit (first and / or second) device light 101 comprising a second linear polarization in an optical path to the luminescent material 200. Yet additionally, in such embodiments, the second beam combiner 1520 may be configured to (at least partially) reflect luminescent material light 201 having a luminescent material centroid wavelength ( imc) in an optical path to the light exit 1090. Especially, the luminescent material centroid wavelength ( imc) may be selected from the wavelength range of 500-780 nm. Hence, in embodiments, the second beam combiner 1520 may comprise a polarizing beam splitter PBS with further spectral requirement (i.e. a dichroic beam combiner function) such that it may combine (blue) diffused device light 711 with (e.g. yellow) luminescent material light 201 (i.e., the second beam combiner 1520 may comprise a combined PBS,DBC).

[0201] Yet alternatively, in embodiments when the diffuser 710 may be configured in the reflective mode, an optical axis Oi of incoming device light 101 and an optical axis Orof outgoing diffused device light 711 (relative to the diffuser 710) may have a mutual angle p. In such embodiments, the mutual angle P may be selected from the range of 80°<p<140°. In specific embodiments, the optical axis Oi of incoming device light 101 and the optical axis Orof outgoing diffused device light 711 (relative to the diffuser 710) may have an orthogonal direction relative to each other. In other words, in such embodiments, the diffuser assembly 700 may comprise a non-collinear (reflective) diffuser assembly 700.

[0202] For example, Fig. 2 schematically depicts a second basic configuration of the light generating system 1000 comprising only a single geometric beam combiner GBC1 (i.e. the first beam combiner 1510) and a single dichroic beam combiner DBC (i.e. the second beam combiner 1520) as beam splitting / combining components. Here, no polarizing components are used at all. Again, the first device light 111 and the second device light 121 may be combined via the GBC1, and this combined device light 101,111,121 may be projected via an integrator 570 onto the second beam combiner 1520. All this device light 101,111,121 may be directed via condenser lenses 560 to the luminescent material 200. The luminescent material light 201 may be collected and collimated via the same lenses 560 and projected (back again) towards the second beam combiner 1520. As the reflection and transmission properties of the second beam combiner 1520 (especially the DBC) may be opposite for the luminescent material light 201 and the (diffused) device light 101,(711) now the second beam combiner 1520 may separate the luminescent material light 201 from the optical path of the device light 101,111,121 that was used to excite the luminescent material

[0203] 200, and the luminescent material light 201 may accordingly be projected (and condensed) to the light exit 1090.

[0204] In such embodiments, similarly to the embodiment depicted in Fig. 1, the light generating system 1000 may comprise the first beam splitter 1505 configured to direct at least part of the (first and second) device light 101 (, 111,121) received by the first beam splitter 1505 in an optical path to the diffuser assembly 700 and to direct at least another part of the (first and second) device light 101(111,121) received by the first beam splitter 1505 in an optical path to the luminescent material 200. Alternatively, in embodiments, such as depicted here in Fig. 2, the two or more light generating devices 100 (of the light generating system 1000) may comprise a third light generating device 130 configured to generate third device light 131. Especially, in embodiments, the third device light 131 may have a third centroid wavelength (Acs) selected from the wavelength range of 430-490 nm. Especially, in such embodiments, the diffuser assembly 700 may be configured in a light-receiving relationship with the third light generating device 130 (and optionally additionally the first beam splitter 1505, such as e.g. depicted in Fig. 4).

[0205] As depicted in Fig. 2, the second beam combiner 1520 may especially be configured to transmit (blue) device light 101 (,711) and to reflect luminescent material light

[0206] 201. Conversely, in embodiments (not depicted), the light generating system 1000 may be the same as depicted in Fig. 2, but with the second beam combiner 1520 being configured to reflect (blue) device light 101 (,711) and to transmit luminescent material light 201. Such an embodiment may particularly be interesting as it may enable a configuration with all light generating devices conveniently located in a single plane. As such, the configuration may enable a single heat sink configuration for (all of) the light generating devices 100. Such configuration may allow for compact fixtures.

[0207] Hence, in embodiments as depicted in Fig. 2, the third light generating device 130 may be used to provide diffused device light 711 to the light exit 1090. For that, the output beam (i.e. the third device light 131) of the third device light source 130 may be projected and condensed onto the (reflective) diffuser 710. The reflectively diffused device light 711 may subsequently be collected and collimated, and projected towards the second beam combiner 1520. Thanks to the use of a non-collinear reflective diffuser 710, the direction of the optical axis of the reflectively diffused device light 711 and the direction of the optical axis of the incident device light 101,131 may be different, by which the diffused light 711 may be separated from the optical path of the device light 101,131 that was incident on the reflective diffuser 710. Via the second beam combiner 1520 (especially the DBC) the reflectively diffused device light 711 may be combined with the luminescent material light 201 and projected to the light exit 1090. In such embodiments, there may not be any polarization requirements to the reflective diffuser 710 or transmissive integrator 570 (e.g. small-angle transmissive diffuser) components, nor to the DBC, nor to the device light sources 100. A consequence may, however, be that color point tuning may need to be realized by changing the output power ratio of the third light generating device 130 to the first and / or second light generating devices (110 + 120), and for different output CCT values there are different maximum total engine powers.

[0208] Furthermore, in embodiments, as described above the light generating system may comprise the first beam splitter 1505. Conversely to the above described, in embodiments, the first beam splitter 1505 may comprise a neutral beam splitter (NBS). Especially, in embodiments, the neutral beam splitter (NBS) may be configured to direct x% of light received by the neutral beam splitter (NBS) in an optical path to the diffuser assembly 700 and to direct 100-x% of light received by the neutral beam splitter (NBS) in an optical path to the luminescent material 200. Moreover, in embodiments, x may be selected from the range of 2-98(, especially from the range of 5-50). An embodiment comprising the neutral beam splitter (NBS) may be depicted in Fig. 3.

[0209] Fig. 3 thus schematically depicts a third basic configuration of the light generating system 1000 comprising a single geometric beam combiner GBC1 (i.e., the first beam combiner 1510), a single dichroic beam combiner DBC (i.e., the second beam combiner 1520), and a single neutral beam splitter NBS (i.e. the first beam splitter 1505) as beam splitting / combining components. The NBS does not have specific polarization or dichroic requirements but just splits off a certain part of the incoming (here especially second) device light 101,121 into a separate optical path. In this way a system 1000 with two light sources 100,110,120 can be realized that still can be designed to operate at full light source powers for a specific targeted CCT in the available CCT range without the need of using polarization optics. The application of a neutral beam splitter NBS may be advantageous especially in those cases where there may be no adjustability of the ratio of device light 101 used for diffusion and device light 101 used for luminescent conversion (other than changing the output powers of the respective light sources). By using an NBS with a specific distribution ratio of the incoming light over the two outgoing beams, or a ratio that approximated a desired value, maximum utilization can be made of the installed laser diodes.

[0210] Yet alternatively, in embodiments, the first beam splitter may comprise a (partially) polarizing beam splitter (P)PBS. Especially, in embodiments, device light 101 reaching the (partially) polarizing beam splitter (P)PBS may comprise polarized light. Furthermore, in embodiments, the (partially) polarizing beam splitter (P)PBS may be configured to transmit (first and / or second) device light 101 comprising a first linear polarization and to reflect (first and / or second) device light 101 comprising a second linear polarization, different from the first linear polarization. Alternatively, in embodiments, the (partially) polarizing beam splitter (P)PBS may be configured to reflect (first and / or second) device light 101 comprising a first linear polarization and to transmit (first and / or second) device light 101 comprising a second linear polarization, different from the first linear polarization.

[0211] Fig. 4 thus schematically depicts a fourth basic configuration of the light generating system 1000 comprising a single geometric beam combiner GBC1 (i.e. the first beam combiner 1510), a single dichroic beam combiner DBC (i.e. the second beam combiner 1520), and a single polarizing beam splitter PBS (i.e. the first beam splitter 1505) as beam splitting / combining components. In this configuration, the first device light 111 and the second device light 111,121 may be combined via the GBC1. A (partially) polarizing beam splitter (P)PBS may be used to redistribute the combination of the first and second device light 111,121 and third device light 131 from a third light source 130 over the conversion channel and the diffusion channel. The reflectively diffused device light 711 and the luminescent material light 201 (from the luminescent material 200 operating in a reflective mode) may be combined via the second beam combiner 1520 and projected to the light exit 1090. Thanks to an adjustable polarization setting arrangement (polarization control system 600), in this case implemented in the form of a retarder element 610 especially a birefringent rotator, such as a half-wave plate), the ratio of device light 101 directed into the diffusion channel and directed into the conversion channel may be changed, by which the CCT of the system light 1001 of the light generating system 1000 may be adapted.

[0212] Further, in embodiments, the two or more light generating devices 100 may comprise a fifth light generating device 150. In embodiments, the fifth light generating device 150 may be configured to generate fifth device light 151 having a fifth centroid wavelength (Acs). Especially, in embodiments, the fifth centroid wavelength (Acs) may be selected from the wavelength range of 430-490 nm. In further embodiments, the redirection optical elements 1500 may further comprise a fifth beam combiner 1550. Especially, in embodiments, the fifth beam combiner 1550 may comprise a polarizing beam combiner PBC. In embodiments, the fifth beam combiner 1550 may be configured to direct the fifth device light 151 in an optical path to the luminescent material 200. Especially, in embodiments as depicted, the fifth beam combiner 1550 may be configured in a light-receiving relationship with both the first device light 111 and the fifth device light 151. As such, in embodiments, the fifth beam combiner 1550 may be configured to combine first device light 111 received by the fifth beam combiner 1550 and fifth device light 151 received by the fifth beam combiner 1550 into a same optical path to the luminescent material 200 (in some embodiments via the second beam combiner 1520). In embodiments, the luminescent material 200 may be configured to convert at least part of the device light 101,111,151 received by the luminescent material 200 into luminescent material light 201.

[0213] Hence, in some embodiments such as depicted in Fig. 5, the light generating system 1000 may comprise a single geometric beam combiner GBC1 (i.e. the first beam combiner 1510), a single polarizing beam combiner PBC (i.e. the fifth beam combiner 1550) and a single dichroic beam combiner DBC (i.e. the second beam combiner 1520) as beam splitter / combiner components. Additionally, in such embodiments, a fifth light generating device 150 may be introduced (i.e. a total of four light generating devices 100 may be used). For equal maximum power device light sources, 25% of the device light optical power may be available for the diffusion channel, which may be close to the ideal value when targeting a light engine output CCT of ca 7500 K. In addition, with the configuration as shown in Figure 5 a much preferred lay-out can be realized with all heat dissipating components at one side enabling a single heat sink architecture and the output beam perpendicular to this basic plane of heat sinking pointing away from the heat sink plane while being well centered with the mechanical central axis perpendicular to the heat sinking plane. Such embodiments (i.e. without polarization tunability) may also in the below tables be referred to as non-depicted example 9. Furthermore, in embodiments such as depicted in Fig. 5, the above mentioned conditions for non-depicted example 9 may apply with the further addition of the first beam splitter 1505 and the polarization control system 600. In such embodiments, the first beam splitter 1505 may especially comprise a polarizing beam splitter PBS. The embodiment as presented in Figure 5 shows much similarity with non-depicted example 9, but offers CCT tunability thanks to the addition of a further PBS (i.e. the first beam splitter 1505) and a retarder element 610, here especially configured downstream of the second light generating device.

[0214] In embodiments as depicted in Fig. 1-5 (and Fig. 7 and 8 see below), the luminescent material 200 and the diffuser assembly 700 may be both configured in the reflective mode. Alternatively, in embodiments, one of the luminescent material 200 and the diffuser assembly 700 may be configured in the transmissive mode and the other one of the luminescent material 200 and the diffuser assembly 700 may be configured in the reflective mode.

[0215] For example, an embodiment where the luminescent material 200 may be configured in the transmissive mode is schematically depicted in Fig. 6. In such embodiments, the light generating system 1000 may, e.g., comprise three (blue) light generating devices 100,110,120,150, a single geometric beam combiner GBC1 (i.e. the first beam combiner 1510), a single polarizing beam splitter PBS (i.e. the first beam splitter 1505), a single dichroic beam combiner DBC (i.e. the second beam combiner 1520), a retarder element 610 to enable adjustable redistribution of device light 101,111,121 over the conversion and the diffusion channel, and further a transmissive luminescent material 200 and a (here especially non-collinear) reflective diffuser assembly 700. The luminescent material may, in embodiments, further be configured in an arrangement, such that a low-pass dichroic filter 250 may be configured upstream of the luminescent material 200. In such embodiments, the low-pass dichroic filter 250may be configured to transmit the (blue) device light 101,111,121,151 and may be configured to reflect the luminescent material light 201. In such embodiments, the reflector 550 configured downstream of the luminescent material 200 may especially comprise a small-angle reflective diffuser, such that the engine may be intrinsically robust against safety risks associated with failure of the luminescent material.

[0216] Yet alternatively, in embodiments, the luminescent material 200 and the diffuser assembly 700 may be both configured in the transmissive mode. Such embodiments may also in the below tables be represented by non-depicted example 7. Especially, in such embodiments, the light generating system 1000 may e.g. comprise three (blue) light generating devices 100, a single geometric beam combiner GBC1 (i.e. the first beam combiner 1510), a single polarizing beam splitter PBS (i.e. the first beam splitter 1505), a single dichroic beam combiner DBC (i.e. the second beam combiner 1520), a retarder element 610 configured to enable adjustable redistribution of device light 101 over the conversion and the diffusion channel, and further a transmissive luminescent material 200 and a transmissive diffuser assembly 700. The luminescent material 200 may, in such embodiments, additionally comprise a low-pass dichroic filter 250 configured upstream of the luminescent material 200, which may transmit the (blue) device light 101 and reflect the luminescent material light 201. Furthermore, in such embodiments, the reflector 550 configured downstream of the luminescent material 200 may especially comprise a smallangle reflective diffuser.

[0217] Further, in embodiments, the two or more light generating devices 100 may comprise a fourth light generating device 140. In embodiments, the fourth light generating device 140 may be configured to generate fourth device light 141 having a fourth centroid wavelength (X^). Especially, in embodiments, the fourth centroid wavelength (X^) may be selected from the wavelength range of 600-780 nm (i.e. red device light). Further, in such embodiments, the redirection optical elements 1500 may be configured to direct the fourth device light 141 in an optical path to the diffuser assembly 700. Therefore, in embodiments such as depicted in Fig. 7, the redirection optical elements 1500 may optionally comprise a third beam combiner 1530. Especially, in such embodiments, the third beam combiner 1530 may comprise a second dichroic beam combiner DBC2. Hence, as depicted in Fig. 7, in embodiments, the diffuser 710 may be configured to diffuse at least part of the device light 101 comprising (at least part of) the fourth device light 140 and (at least part of) one or more of first device light 111 and second device light 121, received by the diffuser 710 into diffused device light 711.

[0218] In other words, in such embodiments, again a single geometric beam combiner GBC1 (i.e. the first beam combiner 1510) and a single polarizing beam splitter PBS (i.e. the first beam splitter 1505) are used, but now the light from two blue light generating devices 100,110,120 and one red light generating device 100,140 may be combined using an additional second dichroic beam combiner DBC2 (i.e. the third beam combiner 1530). The blue device light 101,111,121 from the first light generating device 110 and the second light generating device 120 may be combined via the GBC, and subsequently the additional DBC2 may blend-in the red fourth device light 141. The further redistribution of device light 101 over the diffusion and conversion channel may be similar (or even identical) to that in the previous embodiments. Hence, in embodiments, the light generating system may comprise two “blue” light generating devices 100,110,120 and one “red” light generating device 100,140, wherein redistribution of the blue device light may be realized via the PBS,DBC (i.e. the second beam combiner 1520) component. As depicted here, in embodiments, the PBS,DBC (i.e. the second beam combiner 1520) component may be transmissive for luminescent material light 201 outside of the device light 101 spectral bands. Alternatively, in embodiments (not depicted), the PBS,DBC (i.e. the second beam combiner 1520) component may be reflective for luminescent material light 201 outside of the device light 101 spectral bands.

[0219] Hence, in embodiments, the two or more light generating devices 100 may comprise the third light generating device 130. Additionally or alternatively, in embodiments, the two or more light generating devices 100 may comprise the fourth light generating device 140. Especially, as depicted in Fig. 8, the two or more light generating devices 100 may comprise both the third light generating device 130 and the fourth light generating device 140. Furthermore, in such embodiments, the redirection optical elements 1500 may comprise a fourth beam combiner 1540. In embodiments, the fourth beam combiner 1540 may be configured to direct third device light 131 received by the fourth beam combiner 1540 and fourth device light 141 received by the fourth beam combiner 1540 in an optical path to the diffuser assembly 700, optionally via another one of the redirection optical elements 1500 (e.g. as depicted here via the first beam splitter 1505). Especially, in embodiments, the fourth beam combiner 1540 may comprise a second geometric beam combiner GBC2. In embodiments, the second geometric beam combiner GBC2 may comprise a plate comprising geometric-optical features 1513 that may correlate to a geometrical configuration of the third light generating device 130 and the fourth light generating device 140.

[0220] In other words, in embodiments as depicted in Fig. 8, the light generating system 1000 may comprise again three blue light generating devices 100,110,120,130, one red light generating device 100,140, two geometric beam combiners GBC1,GBC2 (i.e. the first beam combiner 1510 and the fourth beam combiner 1540, respectively), one (partially) polarizing beam splitter (P)PBS (i.e. the first beam splitter 1505), one dichroic beam combiner DBC (i.e. the second beam combiner 1520), and a non-collinear reflective diffuser assembly 700. Thanks to the latter, the PBS may be used to redistribute blue device light 101,111,121,131 over the luminescent conversion channel and the diffusion channel, thereby enabling color point tuning by polarization adjustment of one or more of the different types of (blue) device light 101,111,121,131. Furthermore, in these embodiments, the DBC may especially comprise a combination of a band reflection filter for the spectral range between the two (blue and red) device light wavelengths and a low-pass spectral reflection filter that reflects at wavelengths above the red device light.

[0221] The different configurations as depicted in Fig. 1-8 and their specific attributes are summarized in the below table 1 :

[0222] Herein the phrase “system tunable at constant power” may refer to whether the light generating system of that example may enable tunability while all respective light generating devices may be operated at a constant power (in contrast, one could increase the output power of one light generating device and decrease the output power of another, keeping the total power constant, while changing the spectrum of the system output light). Furthermore, the phrase “fraction of blue light used for diffusion (at full power)” may refer to fractions in embodiments where all respective blue light providing light generating devices may have essentially the same nominal (or maximum) output power. Multiple configurations other than the ones depicted in Fig. 1-8 may be possible based on addition of one or more further beam splitting / combining components 1500, one or more further light generating devices 100, one or more further device light 101 wavelengths, two or more different types of light sources 10,20 in one or more of the light generating devices 100, transmissive operational mode of the luminescent material 200, transmissive operational mode of the diffuser assembly 700, or addition of one or more further luminescent materials 200. All these further embodiments may be possible based on application of the principles used in the four basic configurations (described above) and in the general system characterization as described above. Several of the different possible configurations are summarized in the below table 2 as non-depicted examples: Continued table 2:

[0223] Herein, “refl.” may be short for reflective, and “transm.” may be short for transmissive. Further, herein the term “mechanical” for the type of polarization-based tuning may especially refer to tuning realized by mechanical movement, especially rotation, of at least one light generating device (or assembly of light generating devices and optionally further optical elements). Hence, mechanical may refer to rotation of the light sources, whereas the term “retarder plate” for the type of polarization-based tuning may especially refer to rotation of the retarder plate relative to the (polarizations of the) incident beams of device light. Furthermore, herein the letter Z in the terms “1+Z” and “1-Z” may refer to a respective power of the first subset of lasers (configured to provide light source light (especially laser light) having a centroid wavelength selected from the blue wavelength range (e.g. 430-490 nm)) of one of the light generating devices.

[0224] Here below, the different non-depicted examples (which were not yet discussed above) will be briefly discussed as well.

[0225] For non-depicted example 1 may apply that: only a single geometric beam combiner GBC1 (i.e. the first beam combiner 1510) and a combined element comprising a single polarizing beam splitter PBS (i.e. the first beam splitter 1505) and a single dichroic beam combiner DBC (i.e. the second beam combiner (1520) may be used as beam splitting / combining elements. In such embodiments, color point tuning of the systems output light may be enabled by rotation of a retarder element 610 configured either (i) between the first beam combiner 1510 and the second beam combiner 1520 (i.e. the combined PBS / DBC), or (ii) between the first light generating device 110 or the second light generating device 120 and the first beam combiner 1510. These different locations of the retarder element 610 may result in different tuning ranges for the output color point. In the first embodiment (embodiment i, which may be identical to the embodiment of Fig. 1), the retarder element 610 may act on the output of both light generating devices 110,120, while in the second embodiment (embodiment ii) the retarder element 610 may act only on the output of a single light generating device 100.

[0226] Furthermore, in embodiments, the functionality of the second beam combiner 1520 (DBC) may be inverted. Hence, instead of being transmissive for the luminescent material light 201, in some embodiments, the second beam combiner 1520 (DBC) may be reflective for the luminescent material light 201. In such embodiments, the second beam combiner 1520 (DBC) can be realized as a combination of a pure PBS for blue device light 101 and a pure DBC for luminescent material light 201 versus blue device light 101. This may be convenient as with this configuration the spectral requirements to the PBS coating may be relaxed, i.e., the PBS layer / coating may only need to redistribute the blue device light 101 over the two channels based on the polarization of the incoming device light 101, while the spectral properties at other wavelengths than those of the blue device light 101 may not be relevant for the PBS layer / coating, and the additional DBC layer / coating may only need to be reflective for luminescent material light 201 and transmissive for blue device light 101(,711). For non-depicted example 2 may apply that: polarization tuning may be realized by mechanical means, i.e., by rotation of one or more of the light generating devices 100,110,120 around the optical axis of the outgoing beam of device light 101,111,121. In such embodiments, no (relative expensive) retarder plate may be required to adjust the CCT of the output light (i.e., without the need to adjust any of the light generating device output powers). Hence, such embodiments may provide a variant of the light generating system

[0227] 1000 of Fig. 1, but with mechanical color point tuning, through adjustable rotation of an assembly of the first light generating device 110 and the second light generating device 120 (e.g. configured on a rotatable platform controllably by the moving element 620.

[0228] For non-depicted example 3 may apply that: the polarization direction of one or more of the light generating devices 100 (e.g. only the first light generating device 110 or only the second light generating device 120, or both) may be adjustable by rotation of said light generating device 100 around its optical axis. Hence, such embodiments may provide a variant of the light generating system 1000 of non-depicted example 1, but with mechanical color point tuning.

[0229] As described above for Fig. 3, in embodiments, a purely dichroic beam splitter / combiner may be used to combine the diffused blue device light 711 and the luminescent light 201 in a light generating system 1000 comprising the two light generating devices 100 and a minimized polarization optics count. As a consequence, these embodiments may not be tunable (at constant light generating device power settings) in their output color point (note that, herein, “tunable” may refer adjustability of the system light

[0230] 1001 CCT without the need to adjust one or more of the output powers of the light generating devices 100). In the embodiment depicted in Fig. 3, polarizing components have been eliminated by applying a non-collinear reflective diffuser 710. Conversely, such as in nondepicted example 4, a collinear reflective diffuser 710 may be applied that may still require a single polarizing beam splitter PBS (i.e. the first beam splitter 1505) and a quarter waveplate 720 to maximize the system efficiency.

[0231] Conversely to the above described, in embodiments, also tunable light generating systems 1000 (alternatively to the ones depicted in Figs. 1-8) may be provided, especially comprising three (blue) light generating devices 100, and a combination of a single geometric beam combiner GBC1 (i.e. the first beam combiner 1510), a single dichroic beam combiner DBC (i.e. the second beam combiner 1520) and a single polarizing beam splitter PBS (i.e. the first beam splitter 1505). For example, in non-depicted example 5 no output CCT tunability may be enabled (at constant light generating device power setting). In this example a “conventional” collinear reflective diffuser assembly 700 and a “conventional” reflective luminescent material 200 may be used. The first device light 111 and the second device light 121 may be combined via GBC1 and may be used to excite the luminescent material 200. The third device light 131 may be provided to (only) the diffuser assembly700 to provide the diffused device light 711. Tuning of the output color point may, in such an example, only be possible by adjustment of the relative output power of the third light generating device 130 relative to the output power of the first light generating device 110 and the second light generating device 120.

[0232] Alternatively, in embodiments, the system light 1001 color point may be adjustable for a fixed setting of the light generating device output powers. With the same number and type of beam splitter / combiner elements as described for non-depicted example 5, this may be enabled by applying the non-collinear reflective diffuser 710. Such embodiments may be encompassed by non-depicted example 6 (and Fig. 4). Especially, in such embodiments, the light generating system 1000 may comprise a (partially) polarizing beam splitter (P)PBS (i.e. the first beam splitter 1505) that may be configured to redistribute device light 101 into the non-collinear reflective diffuser channel and a luminescent conversion channel. Subsequently, the diffused device light 711 and the luminescent material light 201 may be combined via the DBC (i.e. the second beam combiner 1520). Hence, in such embodiments, GBC1 may be configured to combine the first device light 111 and the second device light 121 and provide said device light 101,111,121 to the (P)PBS, which may divide the device light 101,111,121 over the luminescent conversion channel and the diffusion channel. In parallel, the third device light 131 may be projected, along a different input optical path, onto the PBS as well and may be fed into the diffusion channel, the luminescent conversion channel, or both channels. In such embodiments, adjustability may be realized by setting the polarization direction of the output light of one or two of the light generating devices 100,110,120,130, e.g. by using a retarder element 610. Such a retarder element 610 may, in embodiments, be configured in an optical path between the GBC1 and the (P)PBs. Available blue device light power fractions FC and FD for respectively the conversion and the diffusion channel may be expressed (for such embodiments) as: Fc =(X(PI+P2)+YP3) / (PI+P2+P3)

[0233] FD=1-FC where Pi may be the output power of device light source LSi, wherein i = 1, 2, or 3, X may be determined by the orientation of the retarder element 610 and may have a value selected between 0 < X < 1, and Y may be determined by the (P)PBS characteristics with a value selected between 0 < Y < 1.

[0234] Conversely, in embodiments, the retarder element 610 may be configured in an optical path between the third light generating device 130 and the (P)PBS. As a consequence, the system light 1001 color point tuning range of the two different embodiments may, at least potentially, be different. Available blue device light power fractions FC and FD for respectively the conversion and the diffusion channel may be expressed (for such embodiments) as:

[0235] Fc =(Y(PI+P2)+XP3) / (PI+P2+P3)

[0236] FD=1-FC where again X may be determined by the orientation of the retarder element 610 and may have a value selected from 0 < X < 1, and Y may be determined by the (P)PBS characteristics with a value selected from 0 < Y < 1.

[0237] For non-depicted example 8 may apply that: the light generating system 1000 may comprise three (blue) light generating devices, one geometric beam combiner GBC1 (i.e. the first beam combiner 1510) and two polarizing beam splitters PBS’s (i.e. the first beam splitter 1505 and a second polarizing beam splitter), and one dichroic beam combiner DBC (i.e. the second beam combiner 1520) as beam splitting / combining components. In some embodiments, the first beam splitter 1505 may be configured downstream of the GBC1. In other embodiments, the first beam splitter 1505 may be configured upstream of the GBC1. In both embodiments, the first beam splitter 1505 may be used to redistribute device light 101 over the conversion channel and the diffusion channel, while the second polarizing beam splitter may be used to split the collinearly diffuse reflected device light 711 from the optical path of the device light 101 incident on the diffuser 710. Color point tunability along the phosphor load line may be enabled by a retarder element 610 configured downstream of one or more of the light generating devices 100 and upstream of the first beam splitter 1505.

[0238] For non-depicted example 10 may apply that: the light generating system 1000 may comprise a second geometric beam combiner GBC2 (i.e. the fourth beam combiner 1540). Especially, in such an embodiment, the system 1000 may comprise a CCT-tunable configuration comprising two geometric beam combiners GBC1,GBC2 (i.e. the first and fourth beam combiner 1510,1540), two polarizing beam splitters PBS’s (i.e. the first beam splitter 1505 and a second polarizing beam splitter), and four (blue) light generating devices 100,110,120,130,150. Color point tunability along the phosphor load line may be enabled by the retarder element 610. In such embodiments, the first, second, and fifth device light 111,121,151 may be used for luminescent conversion, while the third device light 131 may be distributed over the luminescent channel and the diffusion channel. This means that for equal -power device light sources 0-25% of the (blue) device light 101 may be available for the diffusion channel. By relocation of the retarder element 610, this percentage may be changed. For example, with the retarder element 610 located downstream of the fifth light generating device 150 and upstream of the GBC1, and with the third light generating device 130 emitting p-polarized light, the fraction of (blue) device light 101 available for the diffusion channel may become 25-50%. Alternatively, the retarder element 610 may be located downstream of the GBC1 and upstream of the first beam splitter 1505, resulting (assuming equal polarization of the third and fifth device light 131,151) in 0-50% of the device light 101 may be available for the diffusion channel.

[0239] As described above, in embodiments, (such as in non-depicted example 11) the light generating system 1000 may comprise one or more light generating devices 100 comprising a first subset of solid state light sources 10 (e.g. lasers) configured to provide light source light having a first wavelength, and a second subset of solid state light sources 20 (e.g. lasers) configured to provide light source light having a second wavelength, different from the first wavelength. For example, in embodiments, the light generating system 1000 may comprise the first light generating device 110, the second light generating device 120, a single geometric beam combiner GBC1 (i.e. the first beam combiner 1510), a single PBS (i.e. the first beam splitter 1505), wherein the first light generating device 110 may comprise a subset of lasers configured to generate blue device light 101,111 and a second subset of lasers configured to generate red device light 101,111, while the second light generating device may be configured to (only) generate blue device light 101,121. The two red and blue device light contributions to the system light 1001 may both be diffused by the diffuser assembly 700. In such embodiments, the first beam splitter 1505 may also have reflectance / transmittance requirements in spectral ranges outside that of the blue device light 101, therefore it may also be indicated as PBS,DBC (i.e. a combined second beam combiner 1520 and first beam splitter 1505) component. The device light 101 from both light sources may be combined via the GBC1 and projected to the first beam splitter 1505. The first beam splitter 1505 may further have additional spectral requirements in the luminescent spectral range in case of a beam splitting / combining component that may be transmissive for a substantial part of the luminescent material light 201. In such embodiments, the first beam splitter 1505 may additionally need to be provided with a narrow-band reflective filter to reflect the red device light 101. In case of a beam splitting / combining component ((e.g. a combined second beam combiner 1520 and first beam splitter 1505 component, also referred to as 1505,1520, DBC, PBS) that may be reflective for a substantial part of the luminescent material light 201 (especially in the spectral bands comprising the (blue and / or red, especially red) device light 101), the first beam splitter 1505 may be designed such that it may be reflective for s-polarized (blue and / or red, especially at least red) device light 101 and transmissive for p-polarized (blue and red) device light 101. An additional filter then may be applied that may transmit blue and red device light 101 and may reflect all luminescent material light 201 outside of the spectral bands of the (blue and red) device light 101. Tuning of the output CCT may be enabled by the retarder element 610 located downstream of the second light generating device 120 (and upstream of the GBC1).

[0240] In comparison to the embodiment depicted in Fig. 7 (comprising the second dichroic beam combiner DBC2, i.e., the third beam combiner 1530), the GBC1 (i.e. the first beam combiner 1510) may be configured downstream of the second dichroic beam combiner DBC2 (i.e., the third beam combiner 1530), rather than upstream. Hence, in such embodiments, the second device light 121 may be combined via the GBC1 with the dichroically combined output of the (blue) first device light 111 and the (red) fourth device light 141. This combined device light 111,121,141 may subsequently be projected to the PBS, DBC (i.e. the combined second beam combiner 1520 and first beam splitter 1505) component where the blue device light 101,111,121 may be redistributed over the conversion and the diffusion channel.

[0241] For non-depicted example 12 may apply that: the light generating system 1000 may comprise two blue light generating devices 100,110,120 and one red light generating device 100,140, with a single geometric beam combiner GBC1 (i.e. the first beam combiner 1510) and two polarizing beam splitters PBS’s (i.e. the first beam splitter 1505 and a second polarizing beam splitter) as beam splitting / combining elements. In such embodiments, the single GBC1 may be configured to combine the first device light 111 and the second device light 121, the PBS, DBC (i.e. the combined second beam combiner 1520 and first beam splitter 1505) component may be configured to redistribute the blue (first and second) device light 101,111,121 over the conversion and diffusion channels, and a second combined PBS, DBC (i.e. a combined second dichroic beam combiner DBC2 with the fifth beam combiner 1550) may be configured to redirect luminescent material light 201, and diffused blue (i.e. first and / or second) and / or red (i.e. fourth) device light 71 lin an optical path towards the light exit 1090. The light output color point may be tunable along the luminescent converter “load line” via the orientation of a retarder element 610. For non-depicted example 13 may apply that: the light generating system 1000 may comprise three blue light generating device 100,110,120,130 and one red light generating device 100,140, a single geometric beam combiner GBC1 (i.e. the first beam combiner 1510), and two dichroic beam combiners DBC,DBC2 (i.e. the second and third beam combiners 1520,1530). In such embodiments, the first beam combiner 1510 may be configured to combine the first device light 111 and the second device light 121, whereas the third beam combiner 1530) (i.e. DBC2), may be configured to combine the third device light 131 and the fourth device light 141. Furthermore, in such embodiments, the second beam combiner 1520 (i.e. DBC) may be configured to combine the diffused device light 711 with the luminescent material light 201 into the system light 1001. Color point tuneability may, in such embodiments, only be possible by adaptation of the output power of one or more of the light generating devices 100. Such embodiments, may provide an extremely compact and low-cost light generating system 1000 with enlarged color gamut and both relatively high output power and relatively high brightness.

[0242] The non-depicted example 13 (not comprising any polarization optics) may require the use of a non-collinear reflective diffuser assembly 700. Conversely, in embodiments, a collinear reflective diffuser assembly 700 may be applied. Hence, such may be the case for non-depicted example 14. Especially, for non-depicted example 14 may apply that: the light generating system may comprise three blue light generating devices 100,110,120,130, one red light generating device 100,140, a reflective luminescent material 200, a collinear reflective diffuser assembly 700, a single geometric beam combiner GBC1 (i.e. the first beam combiner 1510) that may be configured to combine the first and second device light 111,121, a second dichroic beam combiner DBC2 (i.e. the third beam combiner 1530) that may be configured to combine the third and fourth device light 131,141, a dichroic beam combiner DBC (i.e. the second beam combiner 1520) that may be configured to combine the diffused device light 711 with the luminescent material light 201 into the system light 1001, and the first beam splitter 1505 that may be configured to redirect the diffused device light 711 from the optical path of the incident device light 101 towards the light exit 1090 via the third beam combiner 1530. In such embodiments, color point tuneability may only be possible by adaptation of the output power of one or more of the light generating devices 100.

[0243] For non-depicted example 15 may apply that: the light generating system 1000 may comprise three blue light generating device 100,110,120,130 and one red light generating device 100,140, a single geometric beam combiner GBC1 (i.e. the first beam combiner 1510), a single (partially) polarizing beam splitter (P)PBS (i.e. the first beam splitter 1505), and two dichroic beam combiners DBC,DBC2 (i.e. the second and third beam combiners 1520,1530). Further, such embodiments may comprise a non-collinear reflective diffuser assembly 700 and a reflective luminescent material 200. As such, in embodiments, the system 1000 may be CCT-tunable again by polarization setting such as enabled by addition of a retarder element 610. In embodiments, the first beam combiner 1510 may be configured to combine the first device light 111 and the second device light 121, the first beam splitter 1505 may be configured to redistribute blue device light over the diffusion channel and the luminescent conversion channel, the third beam combiner 1530 may be configured to combine the fourth device light 141 with the redistributed (by the first beam splitter 1505,(P)PBS) device light 101 from the first, second, and / or third light generating devices 100,110,120,130 into the diffusion channel, and the second beam combiner 1520 may be configured to combine the diffused device light 711 with the luminescent material light 20 into the system light 1001. Color point tuneability may again be enabled by adaptation of the orientation (e.g. rotation) of a retarder element 610, here especially located downstream of third light generating device 130 and upstream of the (P)PBS. Furthermore, in such embodiments, the first device light 111 and the second device light 121 may be chosen to have any polarization that complies, in combination with the (P)PBS characteristics, in a requested fixed redistribution of this device light 101 over the conversion channel and the diffusion channel. In general, this may preferably be chosen to be s-polarized light, as most blue device light 101 may be needed for the conversion channel.

[0244] For non-depicted example 16 may apply that: the light generating system 1000 may comprise three blue light generating devices 100,110,120,130 and one red light generating device 100,140. Furthermore, in such embodiments, the light generating system 1000 may comprise a non-collinear reflective diffuser assembly 700, two geometric beam combiners GBC1,GBC2 (i.e. the first and fourth beam combiners 1510,1540) and only a single dichroic beam combiner DBC (i.e. the second beam combiner 1520) as beam splitter / combiner components. In such embodiments, the DBC may be configured transmissive for (a substantial portion of) luminescent material light 201. Especially, in such embodiments, the DBC may be configured transmissive in the spectral range of the luminescent material light 201 except of the narrow spectral bands of the (red and blue) device light 101, therefore it may comprise e.g. a dual narrow band spectral reflection filter (or e.g. a narrow-band red reflection filter combined with a long-pass dichroic filter having a cut-off wavelength selected between wavelengths of the blue device light and the luminescent material light). However, in alternative embodiments, the DBC may be configured reflective for (a substantial portion of) luminescent material light 201. Especially, in such embodiments, the DBC may be configured reflective in the spectral range of the luminescent material light 201 except of the narrow spectral bands of the (red and blue) device light 101, therefore it may comprise a combination of a band reflection filter for the spectral range between the two device light wavelengths and a low-pass spectral reflection filter that reflects at wavelengths above the red device light 101. Moreover, in such embodiments as described for non-depicted example 16, color point tuneability may only be possible by adaptation of the output power of one or more of the light generating devices 100,110,120,130,140.

[0245] For non-depicted example 17 may apply that: the light generating system 1000 may comprise three blue light generating devices 100,110,120,130, one red light generating device 100,140, two geometric beam combiners GBC1,GBC2 (i.e. the first and fourth beam combiner 1510,1540), one PBS (i.e. the first beam splitter 1505), and one dichroic beam combiner DBC (i.e. the second beam combiner 1520) as beam splitting / combining components, a reflective luminescent material 200 and a collinear reflective diffuser assembly 700. In such an example, the first beam combiner 1510,GBCl may be configured to combine first device light 111 and second device light 121 and provide said combined device light 101, 111, 121 to the luminescent material 200 (via the second beam combiner 1520, DBC). Conversely, in such an example, the fourth beam combiner 1540,GBC2 may be configured to combine third device light 131 and fourth device light 141 and provide said combined device light 101,131,141 to the diffuser assembly 1700 (via the first beam splitter 1505, PBS). For engines based on a collinear reflective diffuser arrangement, the PBS may be required to separate the diffused device light 711 from the incident non-diffused device light 101. As a consequence, no output light color point tuning by polarization adaptation for one or more of the blue device light output beams may be possible. Furthermore, in such embodiments, the DBC may be reflective in the spectral range of the luminescent material light 200 except of the narrow spectral bands of the (red and blue) device light 101, therefore it may be a combination of a band reflection filter for the spectral range between the two device light wavelengths and a low-pass spectral reflection filter that reflects at wavelengths above the red device light 101. Color point tunability may, in such embodiments, only be possible by adaptation of the output power of one or more of the light generating devices 100. For non-depicted example 18 may apply that: the light generating system 1000 may comprise three blue light generating devices 100,110,120,130, one red light generating device 100,140, two geometric beam combiners GBC1,GBC2 (i.e. the first and fourth beam combiner 1510,1540) and two PBS’s (i.e. the first beam splitter 1505 and a second polarizing beam splitter) as beam splitting / combining components, a reflective luminescent material 200 and a collinear reflective diffuser assembly 700. In such an example, the first beam combiner 1510, GBC1 may be configured to combine first device light 111 and second device light 121 and provide said combined device light 101,111,121 to the luminescent material 200 (via the second beam combiner 1520,DBC and the first beam splitter 1505, PBS). Conversely, in such an example, the fourth beam combiner 1540,GBC2 may be configured to combine third device light 131 and fourth device light 141 and provide (at least part of) said combined device light 101,131,141 to the diffuser assembly 700 (via the second polarizing beam splitter) (and optionally provide at least part of the third device light 131 to the diffuser assembly 700). Thanks to the addition of the second PBS, the output CCT may be made tunable by adaptation of the polarization of the device light 101 from one or more of the blue light generating devices 100,110,120,130. In particular, both PBS’s may have additional spectral requirements on reflectance and / or transmittance outside of the spectral band of the blue device light 101. In embodiments, the first PBS may be configured to redistribute the blue device light 101 (especially the third device light 131) over the luminescent conversion channel and the diffusion channel, but may also reflect s-polarized red device light 101,141, transmit p-polarized red device light 101,140, and transmit luminescent material light 201 in the spectral range between the red and blue device light 101 and at wavelengths longer than that of the red device light 101. Color point tunability by adaptation of the polarization in the blue (third) device light 101,(131) may be enabled by the addition of the retarder element 610.

[0246] For non-depicted example 19 may apply that: the (complex) combination of requirements to the PBS in the previous embodiment that may redistribute the blue device light 101 over the diffusion channel and the conversion channel may be simplified by adding a spectral transmittance / reflectance filter component without polarization splitting requirements to take care of the combination of diffused device light 711 and luminescent material light 201. Hence, in embodiments, the light generating system 1000 may comprise three blue light generating devices 100,110,120,130, one red light generating device 100,140, a collinear reflective diffuser assembly 700, a reflective luminescent material 200, two geometric beam combiners GBC1,GBC2 (i.e. the first and fourth beam combiners 1510,1540), two PBS’s (i.e. the first beam splitter 1505 and a second polarizing beam splitter) and one DBC (i.e. the second beam combiner 1520). Both PBS’s may have requirements on reflectance and / or transmittance for both device light wavelengths, but not for any other wavelength. The first PBS 1505 may be configured to redistribute the blue device light 101 (e.g. one or more of the first, second, and third device light 111,121,131) over the luminescent conversion channel and the diffusion channel and also transmit the red device light 101 into the diffusion channel. The second PBS may split the diffused red and blue device light 711 from the optical path of the incident non-diffused red and blue device light 101. The DBC may be a spectral band reflection filter reflecting luminescent material light 201 having a wavelength between the red and blue device light bands and in addition may reflect luminescent material light 201 at wavelengths longer than that of the red device light spectral band. Color point tuneability by adaptation of the polarization in the blue (third) device light 101(, 131) may be enabled by the addition of the retarder element 610.

[0247] Fig. 9 further schematically depicts some embodiments of the first beam combiner 1510, especially the geometric beam combiner GBC(l). In embodiments, as described above, the first light generating device 110 (, especially the first laser bank 111,) may comprise a first array 1110 (comprising first lasers 1010 and optics, such as e.g. an array of collimating lenses). Similarly, in embodiments, the second light generating device 120 (, especially the second laser bank 2222,) may comprise a second array 2110 (comprising second lasers 2010). In embodiments, the first array 1110, the second array 2110, (optionally one or more optical elements, such as e.g. the array of collimating lenses described above) and the first beam combiner 1510 may be spatially arranged in relation to each other such that the first device light 111 may be incident on a first side 1511 of the first beam combiner 1510. Additionally, in embodiments, the first array 1110, the second array 2110, (optionally one or more optical elements) and the first beam combiner 1510 may be spatially arranged in relation to each other such that the second device light 121 may be incident on a second side 1512 of the first beam combiner 1510. Furthermore, in embodiments, the first array 1110, the second array 2110, (optionally one or more optical elements) and the first beam combiner 1510 may be spatially arranged in relation to each other such that the first device light 111 and the second device light 121 may be combined by the first beam combiner 1510 to escape from the first beam combiner 1510 via the first side 1511. Further, in embodiments, at least one of the first device light 111 and the second device light 121 may undergo at least one total internal reflection within the first beam combiner 1510. Hence, in embodiments, the first beam combiner 1510 may be configured to combine the first device light 111 and the second device light 121 into a same optical path based on a spatial location on the first beam combiner 1510 where the respective device light 101 may be incident.

[0248] As depicted in Fig. 9, the first light generating device 110 may comprise a first laser bank 1111 comprising a (plurality of) first laser(s) 1010 and the second light generating device 120 may comprise a second laser bank 2222 comprising a (plurality of) second laser(s) 2010. Although not explicitly indicated, one or more of the light generating devices 100 in the embodiments of the previous figures 1-8 may similarly comprise laser banks comprising a (plurality of) laser(s). Furthermore, as described above, in embodiments, the first array 1110 and / or the second array 2110 may comprise an n*m array. In embodiments where n and / or m (of the first array 1110 and / or the second array 2110) comprises >1, the respective array may extend in a direction perpendicular to the figure (i.e., perpendicular to the 2D plane of the figure( / paper)).

[0249] Fig. 10 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. Fig. 10 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. 10 schematically depicts embodiments of a lighting device 1200 selected from the group of a lamp 1, a luminaire 2, a projector device 3, a stage lighting device, a search light, 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.

[0250] 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%. The term “comprise” also includes embodiments wherein the term “comprises” means “consists of’. 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". 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”. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

[0251] 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.

[0252] 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.

[0253] 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.

[0254] In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

[0255] 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.

[0256] 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.

[0257] 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.

[0258] 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) comprising two or more light generating devices (100), a luminescent material (200), a diffuser assembly (700), optics (500), and a light exit (1090), wherein: the two or more light generating devices (100) are configured to generate device light (101); wherein the light generating devices (100) comprise solid state light sources (10,20) individually selected from the group comprising laser diodes, superluminescent diodes, and stacked multi -junction light-emitting diodes; wherein the two or more light generating devices (100) comprise (i) a first light generating device (110), configured to generate first device light (111) having a first centroid wavelength (Xci), wherein the first centroid wavelength (Xci) is selected from the wavelength range of 430-490 nm, and (ii) a second light generating device (120), configured to generate second device light (121) having a second centroid wavelength (X^), wherein the second centroid wavelength (^2) is selected from the wavelength range of 430-490 nm; wherein the first light generating device (110) comprises a first array (1110) comprising a plurality of first solid state light sources (10); wherein the second light generating device (120) comprises a second array (2110) comprising a plurality of second solid state light sources (20); the optics (500) comprise redirection optical elements (1500), wherein the redirection optical elements (1500) comprise a first beam combiner (1510) and a second beam combiner (1520); the first beam combiner (1510) is configured to direct first device light (111) received by the first beam combiner (1510) and second device light (121) received by the first beam combiner (1510) in an optical path to another one of the redirection optical elements (1500); wherein the first beam combiner (1510) comprises a geometric beam combiner (GBC1), wherein the geometric beam combiner (GBC1) comprises a plate comprising geometric-optical features (1513) that correlate to a geometrical distribution of the plurality of first solid state light sources (10) and the plurality of second solid state light sources (20); the optics (500) are configured to direct in a first operational mode of the light generating system (1000) (i) a part of the device light (101), comprising one or more of firstdevice light (111) and second device light (121), in an optical path to the luminescent material (200) via the first beam combiner (1510) and the other one of the redirection optical elements (1500), and (ii) a part of the device light (101) in an optical path to the diffuser assembly (700); the luminescent material (200) is configured to convert at least part of first device light (111) received by the luminescent material (200) and at least part of second device light (121) received by the luminescent material (200) into luminescent material light (201); the diffuser assembly (700) comprises a diffuser (710); wherein the diffuser (710) is configured to diffuse at least part of the device light (101) received by the diffuser (710) into diffused device light (711); the second beam combiner (1520) is configured to direct luminescent material light (201) received by the second beam combiner (1520) and diffused device light (711) received by the second beam combiner (1520) in an optical path towards the light exit (1090); wherein the second beam combiner (1520) comprises a dichroic beam combiner (DBC); the first light generating device (110) comprises a first laser bank (1111) comprising a plurality of first lasers (1010); wherein the second light generating device (120) comprises a second laser bank (2222) comprising a plurality of second lasers (2010); and wherein the first array (1110), the second array (2110), and the first beam combiner (1510) are spatially arranged in relation to each other such that: the first device light (111) is incident on a first side (1511) of the first beam combiner (1510); the second device light (121) is incident on a second side (1512) of the first beam combiner (1510); the first device light (111) and the second device light (121) are combined by the first beam combiner (1510) to escape from the first beam combiner (1510) via the first side (1511); at least one of the first device light (111) and the second device light (121) undergoes at least one total internal reflection within the first beam combiner (1510); and wherein: the light generating system (1000) is configured to generate in the first operational mode of the light generating system (1000) system light (1001) comprising at least part of the diffused device light (701) and at least part of the luminescent material light(201), wherein the system light (1001) is white light having a correlated color temperature selected from the range of 2000-12000 K and a color rendering index of at least 65.

2. The light generating system (1000) according to claim 1, wherein the first beam combiner comprises a light transparent material selected from the group comprising a glass material, a polymeric material and a ceramic material.

3. The light generating system (1000) according to any one of the preceding claims, wherein one of the following applies: one of the luminescent material (200) and the diffuser assembly (700) is configured in the transmissive mode and the other one of the luminescent material (200) and the diffuser assembly (700) is configured in the reflective mode; the luminescent material (200) and the diffuser assembly (700) are both configured in the transmissive mode; and the luminescent material (200) and the diffuser assembly (700) are both configured in the reflective mode.

4. The light generating system (1000) according to any one of the preceding claims, wherein the diffuser (710) is configured in the reflective mode, wherein an optical axis (Oi) of incoming device light (101) and an optical axis (Or) of outgoing diffused device light (711) have a mutual angle (P), wherein the mutual angle (P) is selected from the range of 80°<p<140°.

5. The light generating system (1000) according to any one of the preceding claims 1-3, wherein the diffuser (710) is configured in the reflective mode, wherein (i) an optical axis (Oi) of incoming device light (101) and an optical axis (Or) of outgoing diffused device light (711) have a parallel direction relative to each other, and (ii) the incoming device light (101) comprises polarized light; wherein the diffuser assembly (700) comprises a quarter waveplate (720) configured in an optical path between at least one of the redirection optical elements (1500) and the diffuser (710); wherein the quarter waveplate (720) is configured to convert linear polarized light received by the quarter waveplate (720) into elliptical polarized light and to convert elliptical polarized light received by the quarter waveplate (720) into linear polarized light; and wherein the second beam combiner (1520)further comprises a polarizing beam splitter (PBS), wherein the second beam combiner (1520) is configured to:(i) transmit device light (101) comprising a first linear polarization in an optical path to the diffuser assembly (700), (ii) reflect device light (101) comprising a second linear polarization in an optical path to the luminescent material (200), and (iii) transmit luminescent material light (201) having a luminescent material centroid wavelength ( imc) in an optical path to the light exit (1090), wherein the luminescent material centroid wavelength ( imc) is selected from the wavelength range of 500-780 nm; or(i) reflect device light (101) comprising a first linear polarization in an optical path to the diffuser assembly (700), (ii) transmit device light (101) comprising a second linear polarization in an optical path to the luminescent material (200), and (iii) reflect luminescent material light (201) having a luminescent material centroid wavelength ( imc) in an optical path to the light exit (1090), wherein the luminescent material centroid wavelength ( imc) is selected from the wavelength range of 500-780 nm.

6. The light generating system (1000) according to any one of the preceding claims, wherein the redirection optical elements (1500) comprise a first beam splitter (1505) configured to direct at least part of the device light (101) received by the first beam splitter (1505) in an optical path to the diffuser assembly (700) and to direct at least another part of the device light (101) received by the first beam splitter (1505) in an optical path to the luminescent material (200); wherein the diffuser assembly (700) is configured in a lightreceiving relationship with the first beam splitter (1505).

7. The light generating system (1000) according to claim 6, wherein the first beam splitter (1505) comprises one of: a neutral beam splitter (NBS) configured to direct x% of light received by the neutral beam splitter (NBS) in an optical path to the diffuser assembly (700) and to direct 100-x% of light received by the neutral beam splitter (NBS) in an optical path to the luminescent material (200), wherein x is selected from the range of 2-98; a polarizing beam splitter (PBS), wherein device light (101) reaching the polarizing beam splitter (PBS) comprises polarized light; and wherein the polarizing beam splitter (PBS) is configured (a) to transmit device light (101) comprising a first linear polarization and to reflect device light (101) comprising a second linear polarization, different from the first linear polarization, or (b) to reflect device light (101) comprising afirst linear polarization and to transmit device light (101) comprising a second linear polarization, different from the first linear polarization.

8. 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 and the radiant flux of the system light (1001), such that: (i) in a primary first operational mode the system light (1001) has a first correlated color temperature (CCT1), and (ii) in a secondary first operational mode the system light (1001) has a second correlated color temperature (CCT2); and wherein CCT2-CCTl>500K.

9. The light generating system (1000) according to claim 8, further comprising a polarization control system (600), wherein the polarization control system (600) is configured to provide, in an optical path to the second beam combiner (1520), an adjustable contribution of (a) device light (101) comprising a first linear polarization and (b) device light (101) comprising a second linear polarization different from the first linear polarization; wherein the polarization control system (600) comprises one or more of a retarder element (610) configured to control a polarization of device light (101) received by the retarder element (610), wherein the control system (300) is configured to control rotation of the retarder element (610); a moving element (620) configured to move one or more of the first light generating device (110), the second light generating device (120), and the first beam combiner (1510), wherein the control system (300) is configured to control the moving element (620).

10. The light generating system (1000) according to any one of the preceding claims, wherein one or more of the following applies: the two or more light generating devices (100) comprise a third light generating device (130) configured to generate third device light (131) having a third centroid wavelength (Acs), wherein the third centroid wavelength (Acs) is selected from the wavelength range of 430-490 nm; wherein the diffuser assembly (700) is configured in a light-receiving relationship with the third light generating device (130); the two or more light generating devices (100) comprise a fourth light generating device (140) configured to generate fourth device light (141) having a fourthcentroid wavelength (X^), wherein the fourth centroid wavelength ( 4) is selected from the wavelength range of 600-780 nm; wherein the redirection optical elements (1500) are configured to direct the fourth device light (141) in an optical path to the diffuser assembly (700); wherein the diffuser (710) is configured to diffuse at least part of the device light (101), comprising fourth device light (140) and one or more of first device light (111) and second device light (121), received by the diffuser (710) into diffused device light (711); and the two or more light generating devices (100) comprise a fifth light generating device (150) configured to generate fifth device light (151) having a fifth centroid wavelength (Acs), wherein the fifth centroid wavelength (Acs) is selected from the wavelength range of 430-490 nm; wherein the polarizing beam splitter (PBS) as defined in claim 7 is configured in a light-receiving relationship with the fifth device light (151).

11. The light generating system (1000) according to claim 10, wherein the two or more light generating devices (100) comprise the third light generating device (130) and the fourth light generating device (140), wherein the redirection optical elements (1500) comprise a fourth beam combiner (1540), wherein the fourth beam combiner (1540) is configured to direct third device light (131) received by the fourth beam combiner (1540) and fourth device light (141) received by the fourth beam combiner (1540) in an optical path to the diffuser assembly (700), optionally via the first beam splitter (1505) as defined in claim 6; and wherein the fourth beam combiner (1540) comprises a second geometric beam combiner (GBC2) comprising a plate comprising geometric-optical features (1513) that correlate to a geometrical configuration of the third light generating device (130) and the fourth light generating device (140).

12. The light generating system (1000) according to any one of the preceding claims, wherein the optics (500) comprise one or more optical integrators (570), wherein the optical integrators (570) are individually selected from the group comprising: a small-angle diffuser, a transmissive volume diffuser, a transmissive surface diffuser, a reflective surface diffuser, a transmissive or reflective diffractive optical element, a transmissive holographic optical element, a single multi lens array, a double multi lens array such as a fly-eye lens array pair, and an integrating polygonal light pipe; and wherein (i) at least one optical integrator (570) is configured in an optical path between the two or more light generating devices (100) and the luminescent material (200), and (ii) at least one optical integrator (570)is configured in an optical path between the two or more light generating devices (100) and the diffuser assembly (700).

13. The light generating system (1000) according to any one of the preceding claims, wherein at least one of the two or more light generating devices (100) comprises at least two types of solid state light sources (10) having different centroid wavelengths, wherein their respective centroid wavelengths differ by at least 10 nm.

14. The light generating system (1000) according to any one of the preceding claims, wherein the first device light (111) has a first centroid wavelength (Xci), wherein the first centroid wavelength (Xci) is selected from the wavelength range of 450-480 nm; wherein the second device light (121) has a second centroid wavelength (X^), wherein the second centroid wavelength (^2) is selected from the wavelength range of 450-480 nm.

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

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