Optimized retardation plates for producing eye-safe white laser light

Abstract

The invention provides a light generating system (1000) comprising N light generating devices (110,...), optics (500), M diffuser assemblies (1710,...), and a light exit (1090); wherein: - a first light generating device (110) is configured to generate first device light (111), comprising an emission band having a first emission peak wavelength (λp1); wherein the first device light (111) comprises light having a first linear polarization; a second light generating device (120) is configured to generate second device light (121) comprising an emission band having a second emission peak wavelength (λp2); wherein the second device light (121) comprises light having the first linear polarization; a third light generating device (130) is configured to generate third device light (131), comprising an emission band having a third emission peak wavelength (λp3); and wherein spectral power distributions of the first device light (111), second device light (121), and third device light (131) mutually differ; - a first diffuser assembly (1710) comprises a first polarization converter (711) and a reflective polarization maintaining first diffuser (712); wherein the first polarization converter (711) comprises a ¼λ retarder with a first wavelength λr1m of maximum retardance; wherein λr1m / 4 is selected from the range of (λp1 / 4 + λp2 / 4) / 2 ± 5 nm; the first diffuser assembly (1710) is configured to diffuse at least part of the first device light (111) and at least part of the second device light (121) received by the first diffuser assembly (1710) into first diffused device light (1711) comprising diffused first device light (111) and diffused second device light (121); and the optics (500) are configured such that at least part of the first diffused device light (1711) and the third device light (131) received by the optics (500) are directed to the light exit (1090); - the light generating system (1000) is configured to generate system light (1001); wherein in a first operational mode of the light generating system (1000) the system light (1001) is white light comprising the first diffused device light (1711) and the third device light (131).

Description

[0001] OPTIMIZED RETARDATION PLATES FOR PRODUCING EYE-SAFE WHITE LASER

[0002] LIGHT

[0003] FIELD OF THE INVENTION

[0004] The invention relates to a light generating system as well as to a lighting device comprising such light generating system.

[0005] BACKGROUND OF THE INVENTION

[0006] Light emitting devices comprising a plurality of light sources are known in the art. WO2022 / 143318, for instance, describes a light emitting device, comprising a first light source, a second light source, a dichroic mirror, a wavelength conversion apparatus, a first light path adjusting apparatus or a second light path adjusting apparatus, and a first scattering optical system. WO2022 / 143318 further states: (a) the light mixing effect of emergent light can be improved by using the first scattering optical system, (b) the color temperature of the emergent light of the light emitting device can be freely adjusted by independently adjusting the power of the first light source and the power of the second light source, (c) a laser capable of emitting light of different dominant wavelengths can be used in the second light source to improve the color rendering index of the emergent light of the light emitting device, and (d) light emitted by the first light source in the present invention is all used for exciting the wavelength conversion apparatus.

[0007] SUMMARY OF THE INVENTION

[0008] High brightness light sources can be used in various applications including spots, stage-lighting, headlamps, home and office lighting, and automotive lighting. For this purpose, laser-phosphor technology can be used, wherein a laser provides laser light and a remote phosphor converts laser light into converted light. A relatively straightforward way to produce white light using lasers is to use laser light in combination to generate phosphor converted light. 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. It appears, however, that using high-brightness sources, such as lasers, also may pose a challenge, in view of safety.

[0009] 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.

[0010] According to a first aspect, the invention provides a light generating system (“system”) comprising N light generating devices , optics, M diffuser assemblies , and a light exit. In embodiments, a first light generating device of the N light generating devices may especially be configured to generate first device light, comprising an emission band having a first emission peak wavelength (Xpi). In embodiments, the first light generating device may comprise a first solid state light source. Further, in specific embodiments, the first device light may comprise light having a first linear polarization (selected from s-polarization and p- polarization). Further, in embodiments a second light generating device of the N light generating devices may especially be configured to generate second device light comprising an emission band having a second emission peak wavelength (Xp2). In embodiments, the second light generating device may (also) comprise a second solid state light source. Further, in embodiments the second device light may comprise light (also) having the first linear polarization. Yet, in embodiments a third light generating device of the N light generating devices may be configured to generate third device light, comprising an emission band having a third emission peak wavelength (Xps). Further, in embodiments the third light generating device may comprise a third solid state light source. Especially, in embodiments (the respective) spectral power distributions of the first device light, the second device light, and the third device light may mutually differ. Further, in embodiments the solid state light sources may individually be selected from the group comprising laser diodes, superluminescent diodes, and stacked multi -junction light-emitting diodes. In embodiments, a first diffuser assembly of the M diffuser assemblies may comprise a first polarization converter and a reflective polarization maintaining first diffuser. Especially, in embodiments the first polarization converter may comprise a ’AZ retarder with a first wavelength Aimof maximum retardance. Further, in specific embodiments Aim / 4 may be selected from the range of (Xpi / 4 + Zp2 / 4) / 2 ± 5 nm. Yet, in embodiments N>3 and 1<M<N. Further, in embodiments the optics may be configured such that at least part of the first device light, and at least part of the second device light, received by the optics, may be directed to the first diffuser assembly. Yet, the first diffuser assembly may in embodiments be configured to diffuse at least part of the first device light and at least part of the second device light received by the first diffuser assembly into first diffused device light (comprising diffused first device light and diffused second device light). Yet, in embodiments the optics may (further) be configured such that at least part of the first diffused device light and the third device light received by the optics may be directed to the light exit. Especially, the light generating system may be configured to generate system light. In specific embodiments, in a first operational mode of the light generating system the system light may be white light comprising the first diffused device light and the third device light. Yet, in further specific embodiments the white light may have a correlated color temperature selected from a range of 1800-12000 K, such as 2000-12000 K, and / or a color rendering index of at least 65. Therefore, in specific embodiments the inventions provides a light generating system (“system”) comprising N light generating devices , optics, M diffuser assemblies , and a light exit; wherein: (A) a first light generating device of the N light generating devices , is configured to generate first device light, comprising an emission band having a first emission peak wavelength (Xpi); wherein the first light generating device comprises a first solid state light source; wherein the first device light comprises light having a first linear polarization (selected from s-polarization and p- polarization); (B) a second light generating device of the N light generating devices is configured to generate second device light comprising an emission band having a second emission peak wavelength (kp2); wherein the second light generating device comprises a second solid state light source; wherein the second device light comprises light (also) having the first linear polarization; (C) a third light generating device of the N light generating devices is configured to generate third device light, comprising an emission band having a third emission peak wavelength (^3); wherein the third light generating device comprises a third solid state light source; (D) spectral power distributions of the first device light, second device light, and third device light mutually differ; (E) the solid state light sources are individually selected from the group comprising laser diodes, superluminescent diodes, and stacked multi -junction light-emitting diodes; (F) a first diffuser assembly of the M diffuser assemblies comprises a first polarization converter and a reflective polarization maintaining first diffuser; wherein the first polarization converter comprises a ’AZ retarder with a first wavelength Aim of maximum retardance; wherein Aim / 4 is selected from the range of (Xpi / 4 + kp2 / 4) / 2 ± 5 nm; wherein N>3 and 1<M<N; (G) the optics are configured such that at least part of the first device light, and at least part of the second device light, received by the optics, are directed to the first diffuser assembly; (H) the first diffuser assembly is configured to diffuse at least part of the first device light and at least part of the second device light received by the first diffuser assembly into first diffused device light (comprising diffused first device light and diffused second device light); (I) the optics are (further) configured such that at least part of the first diffused device light and the third device light received by the optics are directed to the light exit; and (J) the light generating system is configured to generate system light; wherein in a first operational mode of the light generating system the system light is white light comprising the first diffused device light and the third device light; wherein the white light has a correlated color temperature selected from a range of 2000- 12000 K and a color rendering index of at least 65.

[0011] With such a system high intensity and color tunability is possible. Also correlated color temperature (CCT) control may be possible. Further, a high color rendering index (CRI) may be possible. The architecture can be relatively simple, relatively compact, and / or have a relatively low number of components. Yet further, the system may be relatively safe as high-intensity light sources may be applied in combination with reflective elements, and may have an improved safety. Further, a modular system may be provided.

[0012] As indicated above, the light generating system may comprise N light generating devices , optics, M diffuser assemblies , and a light exit.

[0013] A light generating device may comprise one or more light sources. The term “light source” may in principle relate to any light source known in the art. In a specific embodiment, the light source comprises a solid state LED light source (such as an LED or laser diode (or “diode laser”)). The term “light source” may also relate to a plurality of light sources, such as 2-2000 (solid state) LED light sources. Hence, the term LED may also refer to a plurality of LEDs. Further, the term “light source” may in embodiments also refer to a so-called chip-on-board (COB) light source. The term “COB” especially refers to LED chips in the form of a semiconductor chip that is neither encased nor connected but directly mounted onto a substrate, such as a PCB. Hence, a plurality of light emitting semiconductor light source may be configured on the same substrate. In embodiments, a COB is a multi LED chip configured together as a single lighting module. The term “light source” may also refer to a chip scaled package (CSP). A CSP may comprise a single solid state die with provided thereon a luminescent material comprising layer. The term “light source” may also refer to a midpower package. A midpower package may comprise one or more solid state die(s). The die(s) may be covered by a luminescent material comprising layer. The die dimensions may be equal to or smaller than 2 mm, such as in the range of e.g. 0.2-2 mm. Hence, in embodiments the light source comprises a solid state light source. Further, in specific embodiments, the light source comprises a chip scale packaged LED. Herein, the term “light source” may also especially refer to a small solid state light source, such as having a mini size or micro size. For instance, the light sources may comprise one or more of mini LEDs and micro LEDs. Especially, in embodiment the light sources comprise micro LEDs or “microLEDs” or “pLEDs”. Herein, the term mini size or mini LED especially indicates to solid state light sources having dimensions, such as die dimension, especially length and width, selected from the range of 100 pm - 1 mm. Herein, the term p size or micro LED especially indicates to solid state light sources having dimensions, such as die dimension, especially length and width, selected from the range of 100 pm and smaller.

[0014] 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.

[0015] The term “light source” may refer to a semiconductor light-emitting device, such as a light emitting diode (LEDs), a laser diode, a resonant cavity light emitting diode (RCLED), a vertical cavity laser diode (VCSELs), an edge emitting laser (EEL), a photonic crystal surface emitting laser (PCSEL), a vertical external cavity surface emitting laser (VECSEL), etc... The term “light source” may also refer to an organic light-emitting diode (OLED), such as a passive-matrix (PMOLED) or an active-matrix (AMOLED). In a specific embodiment, the light source comprises a solid-state light source (such as an LED or laser diode). In an embodiment, the light source comprises an LED (light emitting diode). The terms “light source” or “solid state light source” may also refer to a superluminescent diode (SLED). 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). The term LED may also refer to a plurality of LEDs.

[0016] 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. 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. The luminescent material may in embodiments be comprised by the light source, such as an LED with a luminescent material layer or dome comprising luminescent material. Such LEDs may be indicated as phosphor converted LEDs or PC LEDs (phosphor converted LEDs). In other embodiments, the luminescent material may be configured at some distance (“remote”) from the light source, such as an LED with a luminescent material layer not in physical contact with a die of the LED. Hence, in specific embodiments the light source may be a light source that during operation emits at least light at wavelength selected from the range of 380-470 nm. However, other wavelengths may also be possible. This light may partially be converted by the luminescent material. 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.

[0017] 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, having band widths as known for lasers.

[0018] The term “light source” may (thus) refer to a light generating element as such, like e.g. a solid state light source, or e.g. to a package of the light generating element, such as a solid state light source, and one or more of a luminescent material comprising element and (other) optics, like a lens, a collimator. A light converter element (“converter element” or “converter”) may comprise a luminescent material comprising element. For instance, a solid state light source as such, like a blue LED, is a light source. A combination of a solid state light source (as light generating element) and a light converter element, such as a blue LED and a light converter element, optically coupled to the solid state light source, may also be a light source (but may also be indicated as light generating device). Hence, a white LED is a light source (but may e.g. also be indicated as (white) light generating device). The term “light source” herein may also refer to a light source comprising a solid state light source, such as an LED, a stacked multi -junction light emitting diode, a laser diode or a superluminescent diode. 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. 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.

[0019] 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.

[0020] 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 laser diode, or a superluminescent diode.

[0021] The term “laser light source” especially refers to a laser. Such laser may especially be configured to generate laser light source light having one or more wavelengths in the UV, visible, or infrared, especially having a wavelength selected from the spectral wavelength range of 200-2000 nm, such as 300-1500 nm. The term “laser” especially refers to a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. Especially, in embodiments the term “laser” may refer to a solid-state laser. In specific embodiments, the terms “laser” or “laser light source”, or similar terms, refer to a laser diode (or diode laser). Hence, in embodiments the light source comprises a laser light source. In embodiments, the terms “laser” or “solid state laser” or “solid state material laser” may refer to one or more of 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.

[0022] A laser may be combined with an upconverter in order to arrive at shorter (laser) wavelengths. For instance, with some (trivalent) 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.

[0023] 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.

[0024] The laser light source may be 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. 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.

[0025] 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).

[0026] The term “solid state material laser”, and similar terms, may refer to a solid state laser like based on a crystalline or glass body dopes 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. 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. Instead of the term “solid state light source” also the term “semiconductor-based 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.

[0027] 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.

[0028] 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.

[0029] In embodiments, laser banks may be applied. Laser banks may also be used to boast the input power. Therefore, in embodiments the system may comprise a plurality of light generating devices configured in a laser bank. A laser bank may comprise a light emitting arrangement comprising an (2D) array of a plurality of laser diodes arranged on a thermally conductive carrier and a (lens array having a) plurality of collimator lenses corresponding to the laser diodes such that each laser diode of the plurality of laser diodes comprises a collimator lens for collimating laser light emitted by the laser diode. The arrangement may comprise a package architecture or a canned architecture. In case of the package architecture a laser diode chip array is arranged on the thermally conductive carrier. A plurality of electrodes may be present for electrically connecting the plurality of laser diodes. The 2D array may e.g. comprise at least 8 laser diodes.

[0030] Especially, the N light generating devices at least comprise a first light generating device, a second light generating device, and a third light generating device. Optionally, the N light generating devices may further comprise a fourth light generating device. Further light generating devices may also be possible, but such embodiments are herein further not described in detail. Note that the term “light generating” device may in embodiments refer to a laser, such as a semiconductor laser (or “laser diode” or “diode laser”), and may in other embodiments refer to a plurality of lasers (such as in a laser bank), like a plurality of semiconductor lasers. Further, especially the light sources of different light generating devices may provide different spectral power distributions. Hence, a laser from one of the light generating devices may differ from a laser from the other light generating devices. Therefore, in embodiments lasers of the first light generating device, lasers of the second light generating device, and lasers of the third light generating device, may mutually differ and may e.g. be selected from different wavelength bins.

[0031] In specific embodiments, each of the solid state light sources may comprise laser diodes, wherein the light generating system may comprise one or more laser banks comprising the solid state light sources . In embodiments, a laser bank may comprise different types of laser diodes. Hence, for two or more different light generating devices, one or more laser banks may be applied. For example, one laser bank may comprise both the first light generating device and the second light generating device. Hence, each of the first, second, third, and optionally fourth, solid state light sources may comprise laser diodes.

[0032] In embodiments, a first light generating device of the N light generating devices may be configured to generate first device light. Especially, the first device light may comprises an emission band having a first emission peak wavelength (Xpi). Especially, in embodiments the first light generating device may comprise a first solid state light source, such as a semiconductor laser. Further, in embodiments the first device light may comprise light having a first linear polarization (selected from s-polarization and p-polarization). Especially, the first emission peak wavelength (Xpi) may be selected from the wavelength range of 380-780 nm, more especially selected from the wavelength range of 400-690 nm.

[0033] Yet, in embodiments a second light generating device of the N light generating devices may be configured to generate second device light. Especially, the second device light may comprise an emission band having a second emission peak wavelength (Xp2). Especially, in embodiments the second light generating device may comprise a second solid state light source, such as a semiconductor laser. Further, in embodiments the second device light may (also) comprise light having the first linear polarization. Especially, the second emission peak wavelength (Xp2) may be selected from the wavelength range of 380-780 nm, more especially selected from the wavelength range of 400-690 nm. Yet, in embodiments a third light generating device of the N light generating devices is configured to generate third device light. Especially, the third device light may comprise an emission band having a third emission peak wavelength (Xps). Especially, in embodiments the third light generating device may comprise a third solid state light source, such as a semiconductor laser. Further, though not necessarily, in embodiments the third device light may (also) comprise light having linear polarization (selected from s-polarization and p-polarization) (see further also below). Especially, the third emission peak wavelength (Xp2) may be selected from the wavelength range of 380-780 nm, more especially selected from the wavelength range of 400-690 nm.

[0034] As indicated above, in embodiments the spectral power distributions of the first device light, second device light, and third device light may mutually differ.

[0035] In embodiments, two spectral power distributions may differ when, comparing normalized spectral power distributions (on wavelength scale), at least one has at maximum 95% overlap with the other one, such as at maximum 90% overlap with the other one, like at maximum 85% overlap with the other one.

[0036] Further, in specific embodiments the solid state light sources may be individually selected from the group comprising laser diodes, superluminescent diodes, and stacked multi -junction light-emitting diodes. In general, the solid state light sources may be selected from the same type of solid state light sources, like all may comprise laser diodes, though this is not necessarily the case. However, also (normal) LEDs may be applied (as solid state light sources).

[0037] Even though two light generating devices may have different spectral power distributions, herein a single diffuser assembly may be used to diffuse light of both of the two different light generating devices.

[0038] When there are three different light generating devices, a first diffuser assembly may be used to diffuse the light of both of the two different light generating devices and a second diffuser assembly may be used to diffuse the light of the other one of the light generating devices.

[0039] When there are four different light generating devices, a first diffuser assembly may be used to diffuse the light of both of the two different light generating devices, and either a second and a third diffuser assembly may be used to diffuse the light of the two other ones of the light generating devices, respectively, or a second diffuser assembly may be used to diffuse the light of both the two other ones of the light generating devices. Therefore, in embodiments a first diffuser assembly of the M diffuser assemblies comprises a first polarization converter and a reflective polarization maintaining first diffuser. Further, especially, in embodiments N>3 and 1<M<N. Further, in embodiments the first polarization converter may comprise a Vkk retarder with a first wavelength Aimof maximum retardance, wherein Aim / 4 is selected from the range of (Xpi / 4 + XP2 / 4) / 2 ± 5 nm, like e.g. (Xpi / 4 + kP2 / 4) / 2 ± 2 nm. In this way, the first diffuser assembly may diffuse the light of two different light generating devices and may be optimized to a kind of average wavelength of the device light of the two different light generating devices. By selected a wavelength of maximum retardance between the peak wavelengths (Xpi and Xp2), retardance for the beams of light from the different types of device light may be more optimized, than when selecting the wavelength of maximum retardance at the peak wavelength of one different device light.

[0040] The light generating system, including the first diffuser assembly, may be configured such that (i) the first device light and the second device light reaching the first polarization converter and comprising (light having) the first polarization are converted by the first polarization converter into elliptically polarized light having a first handedness, (ii) the elliptically polarized light having the first handedness propagates to the reflective polarization maintaining first diffuser, (iii) the reflective polarization maintaining first diffuser converts at least part of the elliptically polarized light having the first handedness into elliptically polarized diffused light having a second handedness, different from the first handedness (iv) the elliptically polarized diffused light having the second handedness propagates to the first polarization converter, and (v) the elliptically polarized diffused light having the second handedness reaching the is converted into the diffused device light having a second linear polarization, different from the first linear polarization. Similarly, this may in embodiments apply to other diffuser assemblies.

[0041] Further, as indicated above, the light generating system may be configured such that the optics are configured such that at least part of the first device light, and at least part of the second device light, received by the optics, are directed to the first diffuser assembly. In this way, diffused first device light and diffused second device light may be provided. Hence, especially the first diffuser assembly may be configured to diffuse at least part of the first device light and at least part of the second device light received by the first diffuser assembly into first diffused device light (comprising diffused first device light and diffused second device light). As will be clear from the above the first diffuser assembly, more especially the reflective polarization maintaining first diffuser, may thus be operated in the reflective mode.

[0042] Herein, a polarization maintaining diffuser may be configured to substantially maintain the polarization of the incident light upon diffusion (and in some embodiments reflection)(even though the handedness may (thus) change). Such embodiments may be beneficial as depolarization at the diffuser may be reduced, therewith improving the efficiency of the contribution of the diffuser arrangement to the system light. For instance, in embodiments, the diffuser may comprise a metal coated surface textured glass substrate mounted on a heat conductive material such as e.g. a metal or a ceramic. In such embodiments, the heat conductive material may be configured to conduct away heat that may be generated in the diffuser due to some absorption of incident device light.

[0043] Further, the optics may be configured such that at least part of the first diffused device light received by the optics is directed to the light exit. To this end, the optics may comprise a primary redirection optics. The primary redirection optics may in embodiments be configured to transmit first device light and second device light, and reflect first diffused device light. In other embodiments, the primary redirection optics may in embodiments be configured to reflect first device light and second device light, and transmit first diffused device light. Hence, especially the optical path of the first device light and second device light reaching the primary redirection optics and the optical path of the first diffused device light emanating from the primary redirection optics may essentially be orthogonal.

[0044] In specific embodiments, the primary redirection optics may be polarization based. Hence, the first device light and second device light reaching the primary redirection optics may comprise the same polarizations, such as both essentially s-polarized or both essentially p-polarized, etc. Hence, the first diffused device light may comprise a linear polarization orthogonal to the linear polarizations of the first device light and second device light. Hence, in embodiments the first device light and second device light may essentially be s-polarized and the first diffused device light may essentially be p-polarized, or the first device light and second device light may essentially be p-polarized and the first diffused device light may essentially be s-polarized.

[0045] Especially, the primary redirection optics may be configured in the optical path of the first device light and second device light propagating from the first redirection optics (see further below) to the first diffuser assembly. Further, the primary redirection optics may be configured upstream of the light exit. Hence, in embodiments the optics may comprise primary redirection optics, configured to (a) transmit first device light and second device light, and reflect first diffused device light, or (b) reflect first device light and second device light 121), and transmit first diffused device light. Further, the primary redirection optics may be polarization based. Especially, the light generating system may be configured such that the first device light and second device light reaching the primary redirection optics comprise the same polarizations. Further, in embodiments the primary redirection optics may be configured in the optical path of the first device light and the second device light propagating from the first redirection optics to the first diffuser assembly. Yet, in embodiments the primary redirection optics may be configured upstream of the light exit.

[0046] Yet further, in embodiments the optics may be configured such that at least part of the first diffused device light and the third device light received by the optics are directed to the light exit. In this way, first diffused device light and the third device light may escape from the light generating system (in an operational mode of the light generating system). Hence, the optics may be configured to combine the first diffused device light and the third device light and direct them to the light exit. As indicated above, in embodiments to this end the optics may comprise the primary redirection optics.

[0047] In embodiments the light generating system may be configured to generate system light; wherein in a first operational mode of the light generating system the system light comprises the first diffused device light and the third device light. More especially, in the in the first operational mode of the light generating system, the system light may be white light comprising the first diffused device light and the third device light. Even more especially, in embodiments the white light may have a correlated color temperature selected from a range of 2000-12000 K and a color rendering index of at least 65 (though other values may also be possible; see also below). In embodiments, the CRI may be at least 70.

[0048] In specific embodiments, the first light generating device may comprises at least 4 or at least 8 or at least 12 first laser diodes, and / or the second light generating device may comprises at least 4 or at least 8 or at least 12 second laser diodes, and / or the third light generating device may comprises at least 4 or at least 8 or at least 12 third laser diodes. However, also more than 12 laser diodes may be applied, like at least 16. In embodiments, for each of the N light generating devices may apply that they comprise at least four, more especially at least 8, yet even more especially at least 12, such as at least 16 laser diodes Several options are possible, for instance the first diffuser assembly may be used to diffuse (a) different types of blue light, (b) blue and green light, (c) different types of green light, (d) green and yellow light, (e) different types of yellow light, (f) yellow and orange light, (g) different types of orange light, (h) orange and red light, or (i) different types of red light. When the second diffuser assembly is applied, the same options may apply, though the diffuser assemblies will especially diffuse different combinations of light types (see also below).

[0049] Here below, it is further especially referred to the peak wavelengths of the device light. Different peak wavelengths may especially imply different spectral power distributions.

[0050] In embodiments, the first emission peak wavelength (Xpi), the second emission peak wavelength (Xp2), and third emission peak wavelength (Xp3), are selected from the wavelength ranges of 400-490 nm, 490-590 nm, and 590-690 nm, wherein at least two of the first emission peak wavelength (Xpi), the second emission peak wavelength (Xp2), and third emission peak wavelength (Xp3), are in different wavelength ranges and differ at least 10 nm, such as at least 20 nm. Hence, in specific embodiments a diffuser assembly may be configured to diffuse different types of light but having the same peak wavelength is herein not excluded. Further, in embodiments a diffuser assembly may be configured to diffuse different types of light having different peak wavelengths, but selected from the same wavelength range. Yet, in (other) embodiments, a diffuser assembly may be configured to diffuse different types of light having different peak wavelengths, selected from different wavelength ranges (selected from of 400-490 nm, 490-590 nm, and 590-690 nm).

[0051] Hence, in embodiments at least one of the following may apply: (a) two of the first emission peak wavelength (Xpi), the second emission peak wavelength (Xp2), and third emission peak wavelength (Xp3), are both selected from the wavelength range of 400-490 nm; (b) two of the first emission peak wavelength (Xpi), the second emission peak wavelength (Xp2), and third emission peak wavelength (Xp3), are both selected from the wavelength range of 490-590 nm; (c) two of the first emission peak wavelength (Xpi), the second emission peak wavelength (Xp2), and third emission peak wavelength (Xp3), are both selected from the wavelength range of 590-690 nm; and (d) all three of the first emission peak wavelength (Xpi), the second emission peak wavelength (Xp2), and third emission peak wavelength (Xp3), are each selected from a different wavelength range (selected from 400-490 nm, 490-590 nm, and 590-690 nm).

[0052] When two of the first emission peak wavelength (Xpi), the second emission peak wavelength (Xp2), and third emission peak wavelength (Xp3), are both selected from the wavelength range of 400-490 nm, the third one will be selected from the wavelength ranges of 490-590 nm and 590-690 nm. Further, the third one may differ at least 10 nm, like at least 20 nm (or at least 30 nm, or even more), with each of the other two. Further, in such embodiments the two peak wavelengths selected from the wavelength range of 400-490 nm may have the same or may have different peak wavelengths. In specific embodiments, they may differ at least 10 nm from each other, like at least 20 nm.

[0053] Likewise, when two of the first emission peak wavelength (Xpi), the second emission peak wavelength (Xp2), and third emission peak wavelength (Xp3), are both selected from the wavelength range of 490-590 nm, the third one will be selected from the wavelength ranges of 400-490 nm and 590-690 nm. Further, the third one may differ at least 10 nm, like at least 20 nm (or at least 30 nm, or even more), with each of the other two. Further, in such embodiments the two peak wavelengths selected from the wavelength range of 490-590 nm may have the same or may have different peak wavelengths. In specific embodiments, they may differ at least 10 nm from each other, like at least 20 nm.

[0054] Yet, likewise when two of the first emission peak wavelength (Xpi), the second emission peak wavelength (Xp2), and third emission peak wavelength (Xp3), are both selected from the wavelength range of 590-690 nm the third one will be selected from the wavelength ranges of 400-490 nm and 490-590 nm. Further, the third one may differ at least 10 nm, like at least 20 nm (or at least 30 nm, or even more), with each of the other two. Further, in such embodiments the two peak wavelengths selected from the wavelength range of 590-690 nm may have the same or may have different peak wavelengths. In specific embodiments, they may differ at least 10 nm from each other, like at least 20 nm.

[0055] When all three of the first emission peak wavelength (Xpi), the second emission peak wavelength (Xp2), and third emission peak wavelength (Xp3), are each selected from a different wavelength range selected from 400-490 nm, 490-590 nm, and 590-690 nm), the peak wavelengths may mutually differ at least 10 nm, such as at least about 20 nm, though at least one set of two different peak wavelengths may differ at most 100 nm, such as at most 90 nm.

[0056] In specific embodiments, the first emission peak wavelength (Xpi) and the second emission peak wavelength (Xp2) may (thus) both be selected from the wavelength range of 400-490 nm. Especially, in such embodiments |Xpi-kp2|> 10 nm. Alternatively, in specific embodiments the first emission peak wavelength (Xpi) may be selected from the wavelength range of 400-490 nm and wherein the second emission peak wavelength (Xp2) is selected from the wavelength range of 490-590 nm (or vice versa). Also in such embodiments in such embodiments |Xpi-kp2|> 10 nm may apply. In such embodiments, beams of blue light may be diffused (and combined). In (other) embodiments, the first emission peak wavelength (Xpi) may be selected from the wavelength range of 490-590 nm and the second emission peak wavelength (Xp2) may be selected from the wavelength range of 590- 690 nm (or vice versa). Also in such embodiments in such embodiments |Xpi-kp2|> 10 nm may apply. In such embodiments, beams of green-yellow light and orange-red light may be diffused (and combined). However, |Zpi-kp2|> 20 nm may apply. In specific embodiments, |kpi-kp2|> 30 nm, or even |Zpi-kp2|> 40 nm, may apply. Especially, however, |Zpi-kp2|< 90 nm, such as |Xpi-kp2|< 80 nm.

[0057] 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 or mirrors, reflectors, collimators, lenses, prisms, diffusers, phase plates, polarizers, diffractive elements, gratings, dichroics, arrays of one or more of the aforementioned, 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”). The dichroic beam splitters and / or polarizing beam splitters described herein may also be applied as beam combiners, as different types of light may (also) be combined via such beam splitters.

[0058] As indicated above, in embodiments the optics may comprise a first redirection optics selected from the group of polarization based redirection optics and dichroic based redirection optics. Especially, the first redirection optics may be configured to combine the first device light and the second device light and direct (it) to the first diffuser assembly. Hence, in embodiments the first redirection optics may comprise dichroic based redirection optics, wherein the first redirection optics may be configured to combine the first device light and the second device light and direct the combined first device light and the second device light to the first diffuser assembly.

[0059] Hence, 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 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 polarizing beam combiner (which may also be indicated as polarizing beam splitter). 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 peak wavelengths may be combined, or device light having (substantially) different spectra power distributions may be combined with a dichroic beam combiner (which may also be indicated as dichroic beam splitter).

[0060] The fact that the optics may comprise a first redirection optics does not exclude the presence of other optics, such as mentioned above, and may also include the use of one or more further redirection optics (see also below).

[0061] Especially, the first redirection optics may be a dichroic beam combiner (or dichroic beam splitter). The first redirection optics may in embodiments be configured to transmit first device light and reflect second device light. In other embodiments, the first redirection optics may in embodiments be configured to reflect first device light and transmit second device light. Hence, especially (a) the optical path of one of the first device light and second device light reaching the first redirection optics and (b) the optical path of the combined beam of first device light and second device light emanating from the first redirection optics may essentially be orthogonal. Further, (c) the optical path of the other one of the first device light and second device light reaching the first redirection optics and (d) the optical path of the combined beam of first device light and second device light emanating from the first redirection optics may essentially be parallel. Therefore, in embodiments the optical paths of the first device light and the second device light reaching the first redirection optics may essentially be orthogonal relative to each other.

[0062] Hence, the first device light and second device light reaching the first redirection optics may especially comprise different spectral power distributions, such as different emission peak wavelengths. As can be derived from the above, the first redirection optics may be configured in the optical path of the first device light and second device light propagating from the first light generating device and second light generating device to the first diffuser assembly, more especially in embodiments in the optical path of the first device light and second device light propagating from the first light generating device and second light generating device, via the primary redirection optics, to the first diffuser assembly.

[0063] Note that the terms first, second, and third, as can also be derived from the below, are not necessarily correlated to colors or wavelength values. Hence, for example, the second peak wavelength can be smaller than, the same as, or larger than, the first peak wavelength; the same applies to other peak wavelength combinations. As indicated above, the first light generating device, the second light generating device, and the third light generating device, and the optional fourth light generating device, may all comprise solid state light sources, like diode laser. In a first line of embodiments, one or more, especially, one or two, more especially only one, of these light generating devices may also comprise a luminescent material, which is configured to convert light source comprised by such light generating device. In a second line of embodiments, at least two, more especially all three, and when a fourth light generating device is available, all four light generating devices may be direct solid state light sources, of which the light may end up in the system light escaping from the system, without conversion by a luminescent material.

[0064] The term “luminescent material” especially refers to a material that can convert first radiation, especially one or more of UV radiation and blue radiation, into second radiation. In general, the first radiation and second radiation have different spectral power distributions. Hence, instead of the term “luminescent material”, also the terms “luminescent converter” or “converter” may be applied. In embodiments, the term “luminescence” may refer to phosphorescence. In embodiments, the term “luminescence” may also refer to fluorescence. Instead of the term “luminescence”, also the term “emission” may be applied. Hence, the terms “first radiation” and “second radiation” may refer to excitation radiation and emission (radiation), respectively. Likewise, the term “luminescent material” may in embodiments refer to phosphorescence and / or fluorescence. The term “luminescent material” may also refer to a plurality of different luminescent materials. Examples of possible luminescent materials are indicated below. Hence, the term “luminescent material” may in specific embodiments also refer to a luminescent material composition. Instead of the term “luminescent material” also the term “phosphor” may be applied. These terms are known to the person skilled in the art.

[0065] 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.

[0066] 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 may comprise aluminum (Al); however, in addition to aluminum, B may also partly comprise gallium (Ga) and / or scandium (Sc) and / or indium (In), especially up to about 20% of B, more especially up to about 10 % of B (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.

[0067] In embodiments, the luminescent material may alternatively or additionally comprise one or more of MS:Eu2+and / or LSisN^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 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.

[0068] 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".

[0069] 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.

[0070] 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.

[0071] In an embodiment, M’xM2-2xAX6 comprises K^SiFe (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.

[0072] 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.. 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 (CuInS2) and / or silver indium sulfide (AgInS2) can also be used. Quantum dots show very narrow emission band and thus they show saturated colors. Furthermore the emission color can easily be tuned by adapting the size of the quantum dots. Any type of quantum dot known in the art may be used in the present invention. However, it may be preferred for reasons of environmental safety and concern to use cadmium-free quantum dots or at least quantum dots having a very low cadmium content. 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 nanowires, etcetera. For instance, the device light of the first light generating device and second light generating device may be combined into first diffused device light, wherein these light generating devices do not comprise a luminescent material, and wherein the third light generating device comprises a luminescent material, such that the third device light may comprise luminescent material light. Optionally, such luminescent material light may be diffused via a second diffuser assembly.

[0073] Hence, in embodiments the third solid state light source may be configured to generate third light source light, wherein the third light generating device comprises a luminescent material, wherein the luminescent material is configured to convert at least part of the third light source light into luminescent material light, wherein the third device light comprises the luminescent material light. Especially, the third solid state light source may comprise a diode laser, and the luminescent material may thus convert at least part of the laser light of the diode laser (such as at least about 20% of the laser light). In embodiments, the luminescent material may be configured in physical contact with the third solid state light source, may be dispersed in a light transmissive material in physical contact with the third solid state light source, or may be configured remote from the third solid state light source.

[0074] As indicated above, a second diffuser assembly may be applied to diffuse the third device light, whether or not this third device light comprises luminescent material. Hence, in further embodiments the light generating system may comprise a second diffuser assembly, wherein the second diffuser assembly comprises a second diffuser. Especially, the optics may be configured such that at least part of the third device light, received by the optics, is directed to the second diffuser assembly. Further, especially the second diffuser assembly may be configured to diffuse at least part of the third device light received by the second diffuser assembly (1720) into second diffused device light. Hence, the second diffused device light may comprise diffused third device light. This second diffused device light may thus in embodiments comprise (further diffused) luminescent material light. Yet, in embodiments, as elucidated below, the second diffused device light may also comprise diffused fourth device light. Further, in embodiments the optics may (further) be configured such that at least part of the second diffused device light received by the optics may be directed to the light exit. Hence, in embodiments, in the first operational mode of the light generating system the system light may comprise the first diffused device light and the second diffused device light (with the latter comprising third device light).

[0075] Hence, the light generating system, including the second diffuser assembly, may be configured such that (i) the third device light and optionally the fourth device light reaching the second polarization converter and comprising a first linear polarization are converted by the second polarization converter into elliptically polarized light having a first handedness, (ii) the elliptically polarized light having the first handedness propagates to the reflective polarization maintaining first diffuser, (iii) the reflective polarization maintaining first diffuser converts at least part of the elliptically polarized light having the first handedness into elliptically polarized diffused light having a second handedness, different from the first handedness (iv) the elliptically polarized diffused light having the second handedness propagates to the second polarization converter, and (v) the elliptically polarized diffused light having the second handedness reaching the second polarization converter is converted into the second diffused device light comprising (light having) a second linear polarization, different from the first linear polarization.

[0076] In embodiments, the optics may comprise a secondary redirection optics. The secondary redirection optics may in embodiments be configured to transmit third device light (and optionally fourth device light), and reflect second diffused device light. In other embodiments, the secondary redirection optics may in embodiments be configured to reflect third device light (and optionally fourth device light), and transmit second diffused device light. Hence, especially the optical path of the third device light (and optionally fourth device light) reaching the secondary redirection optics and the optical path of the second diffused device light emanating from the secondary redirection optics may essentially be orthogonal.

[0077] In specific embodiments, the secondary redirection optics may be polarization based. Hence, the third device light and optionally fourth device light reaching the secondary redirection optics may comprise the same polarizations, such as both essentially s-polarized or both essentially p-polarized, etc.

[0078] Hence, assuming the use of both third device light and fourth device light, the second diffused device light may comprise a linear polarization orthogonal to the linear polarizations of the third device light and fourth device light. Hence, in embodiments the third device light and fourth device light may essentially be s-polarized and the second diffused device light may essentially be p-polarized, or the third device light and fourth device light may essentially be p-polarized and the second diffused device light may essentially be s-polarized. In the absence of fourth device light, but applying the second diffuser assembly, in embodiments the third device light may essentially be s-polarized and the second diffused device light may essentially be p-polarized, or the third device light may essentially be p-polarized and the second diffused device light may essentially be s-polarized. Especially, the secondary redirection optics may be configured in the optical path of the third device light (and optionally fourth device light) propagating from the third device light (and optionally fourth device light) to the second diffuser assembly. Further, the secondary redirection optics may be configured upstream of the light exit (and upstream of the primary redirection optics).

[0079] In specific embodiments, the secondary redirection optics may be configured upstream of the primary redirection optics. This may imply that the secondary redirection optics and the primary redirection optics are configured such that second diffused device light and first diffused device light emanate away from the primary redirection optics along essentially the same optical path to the light exit.

[0080] Hence, in embodiments the optics may comprise secondary redirection optics, configured to (a) transmit third device light and fourth device light, and reflect second diffused device light, or (b) reflect third device light and fourth device light 141), and transmit second diffused device light. In embodiments, the secondary redirection optics may be polarization based. Especially, in embodiments the light generating system may be configured such that the third device light and fourth device light reaching the secondary redirection optics may comprise the same polarizations. Further, in embodiments the secondary redirection optics may be configured in the optical path of the third device light and the fourth device light propagating from the second redirection optics to the second diffuser assembly. Yet, in embodiments the secondary redirection optics may be configured upstream of the light exit. Also in embodiments the secondary redirection optics may be configured downstream of the primary redirection optics.

[0081] Note that when a fourth light generating device is available, it may be chosen to either combine the third device light and fourth device light and have it diffused by the second diffuser assembly, or to direct the third device light to the second diffuser assembly and the fourth device light to a third diffuser assembly.

[0082] Hence, the light generating system, including the third diffuser assembly, may be configured such that (i) the fourth device light reaching a third polarization converter and comprising a first linear polarization is converted by the third polarization converter into elliptically polarized light having a first handedness, (ii) the elliptically polarized light having the first handedness propagates to a reflective polarization maintaining third diffuser, (iii) the reflective polarization maintaining third diffuser converts at least part of the elliptically polarized light having the first handedness into elliptically polarized diffused light having a second handedness, different from the first handedness, (iv) the elliptically polarized diffused light having the second handedness propagates to the third polarization converter, and (v) the elliptically polarized diffused light having the second handedness reaching the third polarization converter is converted into the third diffused device light comprising (light having) a second linear polarization, different from the first linear polarization.

[0083] Note that the first linear polarization of the first device light reaching the primary redirection optics and the first linear polarization of the second device light reaching the primary redirection optics may especially be the same linear polarization. Likewise, the third linear polarization of the third device light reaching the secondary redirection optics and the third linear polarization of the fourth device light reaching the secondary redirection optics may especially be the same linear polarization. However, first and third are only indications to distinguish. Hence, they may differ, they may be the same. In the present invention, the first device light and second device light may thus comprise s-polarized light, or essentially consist of s-polarized light, or may thus comprise p-polarized light, or essentially consist of p-polarized light. For the third device light, the polarization may be chosen independent of the polarization of the first device light and second device light, and may thus comprise s-polarized light, or essentially consist of s-polarized light, or may thus comprise p-polarized light, or essentially consist of p-polarized light. Likewise, this may apply to the optional fourth device light, when not combined with the third device light. However, when combined with the third device light, the linear polarization of the third device light reaching the secondary redirection optics and the linear polarization of the fourth device light reaching the secondary redirection optics may especially be the same linear polarization (but may be the same or different from the linear polarization of the first device light and the second device light).

[0084] As indicated above, in embodiments the system light may be white light. In specific embodiments, the third emission peak wavelength (Xp3) may differ at least 10 nm, such as at least about 20 nm, from the first emission peak wavelength (Xpi) and may differ with at least 10 nm, such as at least about 20 nm, from the second emission peak wavelength (kp2). Would the third device light comprise emission from a luminescent material (based on conversion of the third device light), a peak from the emission from the luminescent material may be selected as third emission peak wavelength (Xps).

[0085] As will be clear from the above the second diffuser assembly, more especially the reflective polarization maintaining second diffuser, may thus be operated in the reflective mode. As indicated above, the third light generating device may also be a direct solid state light source, without a luminescent material to convert at least part of the third light source light.

[0086] In embodiments, the third solid state light source may be configured to generate third light source light, wherein at least 80% of the spectral power of the third device light in the visible wavelength range consists of third light source light, more especially at least 90%, like at least 95%, such as 100%. Further, in embodiments the second diffuser assembly may (thus) comprises a second polarization converter, wherein the second diffuser comprises a reflective polarization maintaining second diffuser. Especially, in such embodiments the third device light may comprise light having a third linear polarization (selected from s-polarization and p-polarization).

[0087] Especially, the second polarization converter and / or the second diffuser may in embodiments wherein essentially only third device light is received be optimized for the peak wavelength of the third device light (be it third device light comprising luminescent material light or be it third device light essentially consisting of direct solid state light source light).

[0088] However, in embodiments the light generating system may also comprise a fourth light generating device. The device light thereof may optionally be diffused as well. This can be done via a separate diffuser assembly, or could be done via the (optional) second diffuser assembly, which could in embodiments imply the generation of second diffused device light comprising diffused third device light and diffused fourth device light.

[0089] Hence, in embodiments the light generating system may (further) comprise a fourth light generating device, wherein the fourth light generating device of the N light generating devices may be is configured to generate fourth device light, comprising an emission band having a fourth emission peak wavelength (Xp4). Especially, the fourth light generating device may comprise a fourth solid state light source.

[0090] The fourth solid state light source(s) may be selected from the group comprising laser diodes, superluminescent diodes, and stacked multi -junction light-emitting diodes. However, also (normal) LEDs may be applied. In specific embodiments, the fourth solid state light source(s) may comprise laser diodes, wherein the light generating system may comprise one or more laser banks comprising the fourth solid state light sources.

[0091] In specific embodiments, the third emission peak wavelength (Xp3) and the fourth emission peak wavelength (Xp4) may be the same. In other specific embodiments, the third emission peak wavelength (Xps) and the fourth emission peak wavelength (Xp4) may be different. Especially, the spectral power distributions of the third device light and fourth device light may be different. Especially, the fourth emission peak wavelength (Xp4) differs from both the first emission peak wavelength (Xpi) and the fourth emission peak wavelength (Xp4). In embodiments, |Xpi-kp4|> 5 nm, |Zp2-kp4|> 5 nm, more especially |Xpi-kp4|> 10 nm, |Xp2- kp4|> 10 nm, even more especially |Xpi-kp4|> 20 nm, |Zp2-kp4|> 20 nm. In more specific embodiments, |Xpi-kp3|> 5 nm, |Zp2-kp3|> 5 nm, |Xpi-kp4|> 5 nm, |Zp2-kp4|> 5 nm, and |Xp3-kp4|> 5 nm, may apply, more especially, |Xpi-Xp3|> 10 nm, |Zp2-kp3|> 10 nm, |Zpi-kp4|> 10 nm, |Zp2-kp4|> 10 nm, and |Xp3-kp4|> 10 nm, may apply, |Xpi-Xp3|> 20 nm, |Zp2-kp3|> 20 nm, |Zpi-kp4|> 20 nm, |kp2-kp4|> 20 nm, and |Xp3-kp4|> 10 nm, may apply, such as like all may mutually differ at least 20 nm.

[0092] When using the second diffuser assembly, in embodiments both the third light generating device and the fourth light generating device may not comprise a luminescent material, and the third device light may comprise linearly polarized light and the fourth device light may comprise linearly polarized light. In such embodiments, via polarization multiplexing or via dichroic multiplexing, device light from different light generating devices may be combined provided that they differ in spectral power distribution.

[0093] However, when using the second diffuser assembly, and in (other) embodiments one (or both) of the third light generating device and the fourth light generating device may comprise a luminescent material, via dichroic multiplexing, device light from different light generating devices may be combined provided that they differ in spectral power distribution. Polarization multiplexing may also be possible, but may imply further measures, as the luminescent material light may essentially be non-polarized.

[0094] Especially, the second redirection optics may be a dichroic beam combiner (or dichroic beam splitter). The second redirection optics may in embodiments be configured to transmit third device light and reflect fourth device light. In other embodiments, the second redirection optics may in embodiments be configured to reflect third device light and transmit fourth device light. Hence, especially (a) the optical path of one of the third device light and fourth device light reaching the second redirection optics and (b) the optical path of the combined beam of third device light and fourth device light emanating from the second redirection optics may essentially be orthogonal. Further, (c) the optical path of the other one of the third device light and fourth device light reaching the second redirection optics and (d) the optical path of the combined beam of third device light and fourth device light emanating from the second redirection optics may essentially be parallel. Therefore, in embodiments the optical paths of the third device light and the fourth device light reaching the second redirection optics may essentially be orthogonal relative to each other. Hence, the third device light and fourth device light reaching the second redirection optics may especially comprise different spectral power distributions, such as different emission peak wavelengths. As can be derived from the above, the second redirection optics may be configured in the optical path of the third device light and fourth device light propagating from the first light generating device and second light generating device to the second diffuser assembly, more especially in embodiments in the optical path of the third device light and fourth device light propagating from the third light generating device and fourth light generating device, via the secondary redirection optics, to the second diffuser assembly.

[0095] Hence, in embodiments the fourth device light may comprise light (also) having the third linear polarization. Further, especially the second polarization converter may comprise a ’AZ retarder with a second wavelength A.r2m of maximum retardance. Especially, in embodiments A.r2m / 4 is selected from the range of (kps / 4 + kP4 / 4) / 2 ± 5 nm, like A.r2m / 4 is selected from the range of (kps / 4 + A.P4 / 4) / 2 ± 2 nm. Further, in embodiments the second diffuser assembly may be configured to diffuse (at least part of the third device light (see above) and) the fourth device light received by the second diffuser assembly into the second diffused device light comprising the diffused third device light and diffused fourth device light. As can be derived from the above, by selected a wavelength of maximum retardance between the peak wavelengths (A.P3 and Zp4), retardance for the beams of light from the different types of device light may be more optimized, than when selecting the wavelength of maximum retardance at the peak wavelength of one different device light.

[0096] In embodiments, the third device light and the fourth device light reaching the second polarization converter and having a third linear polarization may be converted by the second polarization converter into elliptically polarized light having a third handedness, (ii) the elliptically polarized light having the third handedness propagates to the second reflective polarization maintaining second diffuser, (iii) the reflective polarization maintaining second diffuser converts at least part of the elliptically polarized light having the third handedness into elliptically polarized diffused light having a fourth handedness, different from the third handedness (iv) the elliptically polarized diffused light having the fourth handedness propagates to the second polarization converter, and (v) the elliptically polarized diffused light having the fourth handedness reaching the second polarization converter is converted into the second diffused device light having a fourth linear polarization, different from the third linear polarization. Hence, the first device light may comprise light having a first linear polarization, especially defined relative to the primary redirection optics, and the second device light may comprise light also having the first linear polarization (especially also defined relative to the primary redirection optics). This first linear polarization may be s- polarization or p-polarization. Hence, the combined first and second device light propagating from the primary redirection optics to the first diffuser assembly (especially its first polarization converter) may also comprise light having the first linear polarization. The first handedness of the combined first and second device light propagating from the first polarization converter to the reflective polarization maintaining first diffuser may be left elliptically polarized, and the second handedness of the first diffused device light propagating from the polarization maintaining first diffuser to the first polarization converter may be right elliptically polarized, or the first handedness of the combined first and second device light propagating from the first polarization converter to the reflective polarization maintaining first diffuser may be right elliptically polarized, and the second handedness of the first diffused device light propagating from the polarization maintaining first diffuser to the first polarization converter may be left elliptically polarized. The first diffused device light emanating from the primary redirection optics, in a direction of the light exit, may comprise light having a second polarization, orthogonal to the first polarization of the light comprised by the first device light and second device light propagating to the primary redirection optics. Hence, would the first device light and the second device light comprise s-polarized light, the first diffused device light emanating from the primary redirection optics may comprise p- polarized light (and vice versa).

[0097] Similarly, this may apply to the embodiments of (i) third light generating device and second diffuser assembly, (ii) third light generating device and second diffuser assembly, and fourth light generating device and third diffuser assembly, or (iii) (i) third light generating device and fourth light generating device and second diffuser assembly (downstream of both the third light generating device and fourth light generating device). For the sake of completeness, the latter is further described in more detail.

[0098] Hence, the third device light may comprise light having a third linear polarization, especially defined relative to the secondary redirection optics, and the fourth device light may comprise light also having the third linear polarization (especially also defined relative to the secondary redirection optics). This third linear polarization may be s- polarization or p-polarization. Hence, the combined third and fourth device light propagating from the secondary redirection optics to the second diffuser assembly (especially its second polarization converter) may also comprise light having the third linear polarization. The third handedness of the combined third and fourth device light propagating from the second polarization converter to the reflective polarization maintaining second diffuser may be left elliptically polarized, and the fourth handedness of the second diffused device light propagating from the polarization maintaining second diffuser to the second polarization converter may be right elliptically polarized, or the third handedness of the combined third and fourth device light propagating from the second polarization converter to the reflective polarization maintaining second diffuser may be right elliptically polarized, and the fourth handedness of the second diffused device light propagating from the polarization maintaining second diffuser to the second polarization converter may be left elliptically polarized. The second diffused device light emanating from the secondary redirection optics, in a direction of the light exit, may comprise light having a fourth polarization, orthogonal to the third polarization of the light comprised by the third device light and fourth device light propagating to the secondary redirection optics. Hence, would the third device light and the fourth device light comprise s-polarized light, the second diffused device light emanating from the secondary redirection optics may comprise p-polarized light (and vice versa).

[0099] In embodiments, the device light of first device light and second device light may comprise light having a polarization orthogonal to the device light of the third light generating device and optional fourth light generating device. Hence, in embodiments the first device light and second device light comprise s-polarized light, especially may essentially consist of s-polarized light, and the third device light and optional fourth device light may comprise p-polarized light, especially may essentially consist of p-polarized light. Alternatively, in embodiments the first device light and second device light comprise p- polarized light, especially may essentially consist of p-polarized light, and the third device light and optional fourth device light may comprise s-polarized light, especially may essentially consist of s-polarized light. In this way, the first diffused device light and second diffused device light may orthogonally propagate to the primary redirection optics, and be combined in a single optical path to the light exit. Other solutions, however, may also be possible, such as the use of a combined polarization beam splitter and dichroic beam splitter, wherein the polarization beam splitter may e.g. only be applied for specific wavelengths.

[0100] Further, the optics may be configured such that at least part of the fourth device light, received by the optics, is directed to the second diffuser assembly. To this end, the optics may comprise the above discussed second redirection optics. Hence, as indicated above, the optics may (further) comprise second redirection optics selected from the group of polarization based redirection optics and dichroic based redirection optics. Further, the second redirection optics may be configured to combine the third device light and the fourth device light and direct (it) to the second diffuser assembly. As indicated above, especially the second redirection optics may comprise a dichroic beam combiner (or dichroic beam splitter).

[0101] Here below, some further specific embodiments are described. Hence, in embodiments the second redirection optics may comprises dichroic based redirection optics. Further, the second redirection optics may be configured to combine the third device light and the fourth device light and direct combined third device light and the fourth device light to the second diffuser assembly.

[0102] In embodiments, the first emission peak wavelength (Xpi) and the second emission peak wavelength (Xp2) may both be selected from the wavelength range of 400-560 nm. Further, especially |Xpi-kp2|> 10 nm may apply. Further, in embodiments, the third emission peak wavelength (Xp3) and the fourth emission peak wavelength (Xp4) may both be selected from the wavelength range of 560-750 nm. Especially, |Xp3-kp4|> 10 nm may apply. Especially, in embodiments (also) |Xpi-kp3|> 10 nm, |Zpi-kp4|> 10 nm,|kp2-kp3|> 10 nm, and |kp2-kp4|> 10 nm may apply. In other embodiments, one or more of, especially all of the following may apply: |Xpi-kp2|> 20 nm, |Zpi-kp3|> 20 nm, |Zpi-kp4|> 20 nm,|kp2-kp3|> 20 nm, and |kp2-kp4|> 20 nm. In specific embodiments, |Xp3-kp4|> 30 nm, or even |Zp3-kp4|> 40 nm, may apply. Especially, however, |Zp3-kp4|< 90 nm, such as |Xp3-kp4|< 80 nm.

[0103] The first light generating device may comprise a first solid state light source. The first solid state light source may be configured to generate first light source light. Especially, the first device light may essentially consist (especially at least 95%) of the first light source light. As can be derived from the above, the first light generating device may comprise a plurality of first solid state light sources, like a plurality of laser diodes (configured in a laser bank). The first device light may essentially consist (especially at least 95%) of the (laser) light of the laser diodes.

[0104] The second light generating device may comprise a second solid state light source. The second solid state light source may be configured to generate second light source light. Especially, the second device light may essentially consist (especially at least 95%) of the second light source light. As can be derived from the above, the second light generating device may comprise a plurality of second solid state light sources, like a plurality of laser diodes (configured in a laser bank). The second device light may essentially consist (especially at least 95%) of the (laser) light of the laser diodes.

[0105] The third light generating device may comprise a third solid state light source. The third solid state light source may be configured to generate third light source light. Especially, the third device light may essentially consist (especially at least 95%) of the third light source light. As can be derived from the above, the third light generating device may comprise a plurality of third solid state light sources, like a plurality of laser diodes (configured in a laser bank). The third device light may essentially consist (especially at least 95%) of the (laser) light of the laser diodes. Note, however, that in other embodiments the third light generating device may comprise a luminescent material. In such embodiments, the device light may comprise luminescent material light and optionally third light source light.

[0106] The fourth light generating device may comprise a fourth solid state light source. The fourth solid state light source may be configured to generate fourth light source light. Especially, the fourth device light may essentially consist (especially at least 95%) of the fourth light source light. As can be derived from the above, the fourth light generating device may comprise a plurality of fourth solid state light sources, like a plurality of laser diodes (configured in a laser bank). The fourth device light may essentially consist (especially at least 95%) of the (laser) light of the laser diodes. It is not excluded that the fourth light generating device may also comprise a luminescent material (see also the embodiments of the third light generating device); however, such embodiments are herein not further described.

[0107] Further, in embodiments the primary redirection optics may be configured to combine orthogonal beams of first diffused device light and second diffused device light. Hence, the primary redirection optics may be configured to directed first diffused device light and second diffused device light, received by the primary redirection optics, to the light exit.

[0108] Further, in embodiments the primary redirection optics may be configured to combine orthogonal beams of (a) first diffused device light and (b) colinear beams of (bl) second diffused device light and (b2) third diffused device light.

[0109] Hence, the primary redirection optics may be configured to directed first diffused device light and second diffused device light and optionally third diffused device light, received by the primary redirection optics, to the light exit.

[0110] Further, in specific embodiments, in the first operational mode of the light generating system the system light may be white light having a correlated color temperature selected from the range of 2000-9000 K and a color rendering index of at least 65, such as at least 70. However, with the present invention also CRTs of at least 80 may be achieved.

[0111] Further, in embodiments the light generating system may comprise a control system configured to control a spectral power distribution of the system light by (individually) controlling the N light generating devices.

[0112] 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. 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 “violet light” or “violet emission”, and similar terms, may especially relate to light having a wavelength in the range of about 380-440 nm. In specific embodiments, the violet light may have a centroid wavelength in the 380-440 nm range. 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). In specific embodiments, the blue light may have a centroid wavelength in the 440-490 nm range. The terms “green light” or “green emission”, and similar terms, may especially relate to light having a wavelength in the range of about 490-560 nm. In specific embodiments, the green light may have a centroid wavelength in the 490-560 nm range. The terms “yellow light” or “yellow emission”, and similar terms, may especially relate to light having a wavelength in the range of about 560-590 nm. In specific embodiments, the yellow light may have a centroid wavelength in the 560-590 nm range. The terms “orange light” or “orange emission”, and similar terms, may especially relate to light having a wavelength in the range of about 590-620 nm. In specific embodiments, the orange light may have a centroid wavelength in the 590-620 nm range. The terms “red light” or “red emission”, and similar terms, may especially relate to light having a wavelength in the range of about 620-750 nm. In specific embodiments, the red light may have a centroid wavelength in the 620-750 nm range. The terms “cyan light” or “cyan emission”, and similar terms, especially relate to light having a wavelength in the range of about 490-520 nm. In specific embodiments, the cyan light may have a centroid wavelength in the 490-520 nm range. The terms “amber light” or “amber emission”, and similar terms, may especially relate to light having a wavelength in the range of about 585-605 nm, such as about 590-600 nm. In specific embodiments, the amber light may have a centroid wavelength in the 585-605 nm range. 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. The term “green-yellow light” may refer to light having a wavelength in the range of about 490-590 nm. In specific embodiments, the “green-yellow light” light may have a centroid wavelength in the 490-590 nm range. The term “orange-red light” may refer to light having a wavelength in the range of about 590-750 nm. In specific embodiments, the “orange-red light” light may have a centroid wavelength in the 590-750 nm range, more especially selected from the 590- 690 nm wavelength range.

[0113] In specific embodiments, colors, or color points of a first type of light and a second type of light may be different when the respective color points of the first type of light and the second type of light differ with at least 0.01 for u’ and / or with at least 0.01 for v’, even more especially at least 0.02 for u’ and / or with at least 0.02 for v’. In yet more specific embodiments, the respective color points of first type of light and the second type of light may differ with at least 0.03 for u’ and / or with at least 0.03 for v’. Here, u’ and v’ are color coordinates of the light in the CIE 1976 UCS (uniform chromaticity scale) diagram. Spectral power distributions of different sources of light having centroid wavelengths differing least 10 nm, such as at least 20 nm, or even at least 30 nm may be considered different spectral power distributions, e.g. different colors. In general, the differences in centroid wavelengths will not be larger than about 400 nm, such as not more than 350 nm. In other specific embodiments, colors or color points of a first type of light and a second type of light may be essentially the same when the respective color points of the first type of light and the second type of light differ with at maximum 0.03 for u’ and / or with at maximum 0.03 for v’, even more especially at maximum 0.02 for u’ and / or with at maximum 0.02 for v’. In yet more specific embodiments, the respective color points of first type of light and the second type of light may differ with at maximum 0.01 for u’ and / or with at maximum 0.01 for v’. Here, u’ and v’ are color coordinate of the light in the CIE 1976 UCS (uniform chromaticity scale) diagram. The color points indicated with u’,v’ may especially refer to the CIE 1976 color points (see ISO CIE 11664-5: Colorimetry - Part5: CIE 1976 L*u*v* color space and u', v' uniform chromaticity scale diagram). Further, in embodiment a spectral power distribution of the system light may be controllable. Therefore, in embodiments the (optional) control system may be configured to control the first light generating devices, the second light generating devices, the third light generating devices and the optional fourth light generating devices. In specific embodiments, the control system may be configured to control one or more of a color point, correlated color temperature, and color rendering index of the system light.

[0114] 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 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.

[0115] 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.

[0116] 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. 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.

[0117] 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.

[0118] 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, which can only operate in a single operation mode (i.e. “on”, without further tunability).

[0119] 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. Hence, the reflective diffuser element may in embodiments be configured to reflect and diffuse at least part of linearly polarized device light received by the diffuser element while especially maintaining at least part of the direction of linearly polarized of device light. Hence, the diffused device light generated by (and propagating from) the diffuser element may have substantially the same, such as exactly the same, direction of polarization as the linearly polarized device light incident on the diffuser element. However, in the case of elliptically polarized light, the reflective diffuser element may in embodiments be configured to reflect and diffuse at least part of the device light received by the diffuser element while especially changing a direction of elliptically polarized device light. Hence, the diffused device light generated by (and propagating from) the diffuser element may at least still partially be elliptically polarized, but having a different direction from the elliptically polarized device light incident on the diffuser element. Especially, the diffuser element may comprise a specular metal reflector comprising a diffuser. The diffuser element may also comprise a diffusers with a metallic coating.

[0120] Especially, the polarization changing element may be configured to change s- polarized light or p-polarized light to elliptically (especially circularly) polarized light having a first handedness (e.g. right-handed or left-handed polarization). The diffuser element may subsequently, in embodiments, change the direction of the circularly polarized light, but the elliptically (especially circularly) polarized light may essentially stay circularly polarized light, but now having a second handedness (e.g. left-handed or right-handed polarization). At least part of the diffused light, having circular polarization, will subsequently propagate from the diffuser element (back) to the polarization changing element, where it will be converted to (diffused) p-polarized light and / or (diffused) s-polarized light, respectively. Therefore, in some embodiments, the polarization changing element may comprise a X / 4 waveplate; wherein the polarization changing element is especially configured in an optical path of the device light between the central optics and the diffuser element. In this way, p-polarized light can be converted in diffused s-polarized light, and s-polarized light can be converted in diffused p-polarized light. Hence, in specific embodiments, the polarization changing element comprises a X / 4 waveplate. Especially, the polarization changing element may be an element that induces a 90° phase shift between the two orthogonal linear polarization components (s and p) of the light. The most common way is to use birefringent material (birefringent rotators), such as a quarter- wave plate. An alternative may be to use the Faraday effect, in which case the phase shift is caused by an applied magnetic field (Faraday rotators). Another alternative may be to use any component or set of components resulting in an up to 180° relative phase shift of one polarization versus the other polarization. In embodiments, such phase shift may be the result of any one of birefringent, electro-optical, thermo-optical, magneto-optical or any other principle known in the art. Hence, the device light may first pass the polarization changing element, whereby the polarization of the device light is changed, then at the polarization maintaining diffuser the device light is diffused, but polarization may essentially be maintained, and subsequently the diffused device light may pass again the polarization changing element, whereby again the polarization is changed. In this way, relatively collimated light having a s or p polarization may be converted in to diffused light having p or s polarization.

[0121] 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”.

[0122] In embodiments, the system may comprise a light exit, like an end window or an (other) optical element, or an opening, from which the system light may escape to the external of the system. The system may comprise a housing, comprising such light exit. The housing may at least partly enclose one or more light generating devices and one or more (other) optical elements. The system light may escape from the light exit. Optics, such as e.g. described above, may be applied to provide an optical path to the light exit and / or to beam shape the system light.

[0123] 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.

[0124] 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 disinfection device, a photochemical reactor, and an optical wireless communication device, comprising the light generating system as defined herein. In specific embodiments, the lighting device may be selected from the group of a lamp, a luminaire, a projector device, an automotive lighting device, stage-lighting device, (or any other lighting device), comprising the light generating system. 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 first light generating devices and second light generating devices, etc.

[0125] 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 Ac = 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.

[0126] BRIEF DESCRIPTION OF THE DRAWINGS

[0127] 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:

[0128] Figs. 1 A-1D schematically depict some aspects of the light generating system; Fig. 2A, B and C shows some spectral power distributions; and Fig. 3 schematically depicts some applications. The schematic drawings are not necessarily to scale.

[0129] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0130] Referring to e.g. Figs. 1 A-1D, in embodiments, the invention may provide a light generating system 1000 comprising N light generating devices 110,..., optics 500, M diffuser assemblies 1710,..., and a light exit 1090. Especially, a first light generating device

[0131] 110 of the N light generating devices 110,..., may be configured to generate first device light 111, comprising an emission band having a first emission peak wavelength Xpi. The first light generating device 110 may comprise a first solid state light source 10. The first device light

[0132] 111 may comprise light having a first linear polarization (selected from s-polarization and p- polarization). Further, especially a second light generating device 120 of the N light generating devices 110,... may be configured to generate second device light 121 comprising an emission band having a second emission peak wavelength Zp2. The second light generating device 120 may comprise a second solid state light source 2. The second device light 121 may comprise light (also) having the first linear polarization. Yet further, especially a third light generating device 130 of the N light generating devices 110,... may be configured to generate third device light 131, comprising an emission band having a third emission peak wavelength Zp3. The third light generating device 110 may comprise a third solid state light source 30.

[0133] A spectral power distributions of the first device light 111, second device light 121, and third device light 131 may mutually differ. Especially, in embodiments the solid state light sources 10,20,30,... may be individually selected from the group comprising laser diodes, superluminescent diodes, and stacked multi -junction light-emitting diodes, though (normal) LEDs may also be selected.

[0134] In embodiments, a first diffuser assembly 1710 of the M diffuser assemblies 1710,... may comprise a first polarization converter 711 and a reflective polarization maintaining first diffuser 712. The first polarization converter 711 may comprise a ’ / retarder with a first wavelength Aim of maximum retardance. Especially, Aim / 4 may selected from the range of (Xpi / 4 + Xp2 / 4) / 2 ± 5 nm. In embodiments, N>3 and 1<M<N, such as 1<M<N.

[0135] Further, in embodiments the optics 500 may be configured such that at least part of the first device light 111, and at least part of the second device light 121, received by the optics 500, are directed to the first diffuser assembly 1710. Especially, the first diffuser assembly 1710 may be configured to diffuse at least part of the first device light 111 and at least part of the second device light 121 received by the first diffuser assembly 1710 into first diffused device light 1711 (comprising diffused first device light 111 and diffused second device light 121).

[0136] Yet, in embodiments the optics 500 may (further) be configured such that at least part of the first diffused device light 1711 and the third device light 131 received by the optics 500 are directed to the light exit 1090.

[0137] Especially, the light generating system 1000 may be configured to generate system light 1001. In embodiments, in a first operational mode of the light generating system 1000 the system light 1001 may white light comprising the first diffused device light 1711 and the third device light 131. Further, in embodiments the white light has a correlated color temperature selected from a range of 2000-12000 K and a color rendering index of at least 65.

[0138] Further, in embodiments, the first emission peak wavelength Xpi, the second emission peak wavelength kP2, and third emission peak wavelength Zp3, are selected from the wavelength ranges of 400-490 nm, 490-590 nm, and 590-690 nm, wherein at least two of the first emission peak wavelength Xpi, the second emission peak wavelength kP2, and third emission peak wavelength A.P3, are in different wavelength ranges and differ at least 10 nm. Alternatively or additionally, in embodiments at least one of the following applies: (A) two of the first emission peak wavelength Xpi, the second emission peak wavelength kP2, and third emission peak wavelength A.P3, are both selected from the wavelength range of 400-490 nm; (B) two of the first emission peak wavelength Xpi, the second emission peak wavelength kP2, and third emission peak wavelength A.P3, are both selected from the wavelength range of 490- 590 nm; (C) two of the first emission peak wavelength Xpi, the second emission peak wavelength kP2, and third emission peak wavelength Zp3, are both selected from the wavelength range of 590-690 nm; and (D) all three of the first emission peak wavelength Xpi, the second emission peak wavelength kP2, and third emission peak wavelength Zp3, are each selected from a different wavelength range.

[0139] In embodiments, the first emission peak wavelength Xpi and the second emission peak wavelength A.P2 are both selected from the wavelength range of 400-490 nm, and wherein |Zpi-kp2|> 10 nm, or the first emission peak wavelength Xpi may selected from the wavelength range of 400-490 nm and wherein the second emission peak wavelength kP2 may selected from the wavelength range of 490-590 nm (or vice versa). Figs. 2A-2C could e.g. be the result of the latter embodiment. In (other) embodiments, the first emission peak wavelength (Xpi) may selected from the wavelength range of 490-590 nm and wherein the second emission peak wavelength Zp2 may selected from the wavelength range of 590-690 nm (or vice versa). Figs. 2A-2C could (alternatively) e.g. be the result of the latter embodiment.

[0140] Hence, in embodiments i the first emission peak wavelength Xpi and the second emission peak wavelength A.P2 are both selected from the wavelength range of 400- 490 nm, and |Xpi-kp2|> 20 nm; or ii the first emission peak wavelength Xpi may selected from the wavelength range of 400-490 nm and wherein the second emission peak wavelength A.P2 may selected from the wavelength range of 490-590 nm, and Xpi-Xp2|> 20 nm; or the first emission peak wavelength Xpi and the second emission peak wavelength kP2 are both selected from the wavelength range of 490-590 nm, and |Xpi-kp2|> 20 nm.

[0141] Referring to Fig. 1 A (and 1c), the system 1000 may comprise secondary redirection optics 540 configured to transmit third device light, and reflect second diffused device light 1721. In other embodiments, the secondary redirection optics 540 may be configured to reflect third device light, and transmit second diffused device light 1721. Hence, especially the optical path of the third device light reaching the secondary redirection optics 540 and the optical path of the second diffused device light 1721 emanating from the secondary redirection optics 540 may essentially be orthogonal. See further also below.

[0142] Referring again to Figs. 1 A-1D, the optics 500 may comprise in embodiments a first redirection optics 505 selected from the group of polarization based redirection optics and dichroic based redirection optics. In embodiments, the first redirection optics 505 may be configured to combine the first device light 111 and the second device light 121 and direct (it) to the first diffuser assembly 1710. Hence, the first redirection optics 505 may be configured to direct the combined first device light 111 and the second device light 121 to the first diffuser assembly 1710.

[0143] In specific embodiments, the third solid state light source 30 may be configured to generate third light source light 31, wherein the third light generating device 130 may comprise a luminescent material 200. In embodiments, the luminescent material 200 may be configured to convert at least part of the third light source light 31 into luminescent material light 201, wherein the third device light 131 may comprise the luminescent material light 201. Fig. 2B could e.g. be the result of the latter embodiment.

[0144] Referring again to Figs. 1 A-1D, the light generating system 1000 may, further comprise a second diffuser assembly 1720. The second diffuser assembly 1720 may comprise a second diffuser 722. In specific embodiments, the third emission peak wavelength kP3 differs with at least 10 nm from the first emission peak wavelength Xpi and differs with at least 10 nm from the second emission peak wavelength Zp2. In specific embodiments, the third emission peak wavelength A.P3 may differ with at least 20 nm from the first emission peak wavelength Xpi and may differ with at least 20 nm from the second emission peak wavelength kP2.

[0145] Further, in embodiments the optics 500 may be configured such that at least part of the third device light 131, received by the optics 500, may directed to the second diffuser assembly 1720. Especially, in embodiments the second diffuser assembly 1720 may be configured to diffuse at least part of the third device light 131 received by the second diffuser assembly 1720 into second diffused device light 1721 comprising diffused third device light 131. Yet, in embodiments the optics 500 may further be configured such that at least part of the second diffused device light 1721 received by the optics 500 may directed to the light exit 1090. Yet, as can be derived from the above, in embodiments in the first operational mode of the light generating system 1000 the system light 1001 may white light comprising the first diffused device light 1711 and the second diffused device light 1721 (comprising third device light 131).

[0146] In (alternative) embodiments, the third solid state light source 30 may be configured to generate third light source light 31, wherein especially at least 80% of the spectral power of the third device light 131 in the visible wavelength range consists of third light source light 31. Yet, in embodiments the second diffuser assembly 1720 may comprise a second polarization converter 721. The second diffuser 722 may comprise a reflective polarization maintaining second diffuser. Further, in embodiments the third device light 131 may comprise light having a third linear polarization (selected from s-polarization and p- polarization). Fig. 2A and 2C could e.g. be the result of these embodiments.

[0147] With reference to Figs. 1C-1D, the light generating system 1000 may further comprise a fourth light generating device 140. Especially, the fourth light generating device 140 of the N light generating devices 110,..., may be configured to generate fourth device light 141. The device light 141 may comprise an emission band having a fourth emission peak wavelength Zp4. Fig. 2C could e.g. be the result of these embodiments.

[0148] In embodiments, (see e.g. also Fig. 2C), the fourth light generating device 140 may comprise a fourth solid state light source 40, wherein |Zpi-kp3|> 5 nm, |kP2-P31> 5 nm, |kpi-kp4|> 5 nm, |Zp2-kp4|> 5 nm, and |Xp3-kp4|> 5 nm, applies.

[0149] Referring to especially Fig. ID, in embodiments the fourth device light 141 may comprise light also having the third linear polarization and the second polarization converter 721 may comprise a Vkk retarder with a second wavelength Xr2m of maximum retardance. Especially, in embodiments A.r2m / 4 may selected from the range of (Xps / 4 + Xp4 / 4) / 2 ± 5 nm. Further, the optics 500 may be configured such that at least part of the fourth device light 141, received by the optics 500, may directed to the second diffuser assembly 1720. Especially, in embodiments the second diffuser assembly 1720 may be configured to diffuse (at least part of the third device light 131 and) the fourth device light 131 received by the second diffuser assembly 1720 into the second diffused device light 1721 comprising the diffused third device light 131 and diffused fourth device light 141.

[0150] Referring to Fig. ID, the optics 500 may further comprise second redirection optics 510 selected from the group of polarization based redirection optics and dichroic based redirection optics. In embodiments, the second redirection optics 510 may be configured to combine the third device light 131 and the fourth device light 141 and direct (it) to the second diffuser assembly 1720. Hence, the second redirection optics 510 may be configured to combine the third device light 131 and the fourth device light 141 and direct combined third device light 131 and the fourth device light 141 to the second diffuser assembly 1720.

[0151] Yet, in embodiments, the first emission peak wavelength Xpi and the second emission peak wavelength kP2 are both selected from the wavelength range of 400-560 nm, and wherein |Zpi-kp2|> 10 nm. Especially, in embodiments the third emission peak wavelength Zp3 and the fourth emission peak wavelength kP4 are both selected from the wavelength range of 560-750 nm, and wherein |Zp3-kp4|> 10 nm. For instance, in embodiments |Xpi-kp3|> 10 nm, |kpi-kp4|> 10 nm,|kp2-kp3|> 10 nm, and |Xp2-kp4|> 10 nm. Fig. 2C could e.g. be the result of these embodiments.

[0152] Hence, in embodiments |Xpi-Xp31> 20 nm, |Zp2-kp3|> 20 nm, |Zpi-kp4|> 20 nm, |kp2-kp4|> 20 nm, and |Xp3-kp4|> 20 nm, may apply. Yet further, |Zpi-kp2|> 20 nm may apply.

[0153] Further, in embodiments each of the solid state light sources 10,20,30,... comprise laser diodes; wherein the light generating system 1000 may comprise one or more laser banks 5 comprising the solid state light sources 10,20,30,.... Referring to Fig. ID, the system 1000 may comprise up to four laser banks 5, comprising the solid state light sources 10,20,30,40.

[0154] Hence, (each of) the laser banks 5 may comprise a light emitting arrangement comprising a 2D array of a plurality of laser diodes arranged on a thermally conductive carrier and a lens array having a plurality of collimator lenses corresponding to the laser diodes such that each laser diode of the plurality of laser diodes may comprise a collimator lens for collimating laser light emitted by the laser diode. Here, by way of example only 2 laser diodes or two arrays of laser diodes are schematically depicted.

[0155] Referring to Figs. 1 A-1D, in embodiments the optics 500 may (further) comprise primary redirection optics 535, configured to a transmit first device light 111 and second device light 121, and reflect first diffused device light 1711, or b reflect first device light 111 and second device light 121, and transmit first diffused device light 1711; wherein the primary redirection optics 535 are polarization based; wherein the light generating system 1000 may be configured such that the first device light 111 and second device light 121 reaching the primary redirection optics 535 comprise the same polarizations; wherein the primary redirection optics 535 may be configured in the optical path of the first device light 111 and the second device light 121 propagating from the first redirection optics 505 to the first diffuser assembly 1710, and wherein the primary redirection optics 535 may be configured upstream of the light exit 1090.

[0156] Yet, referring to Figs. 1 A-1D, in embodiments the optics 500 may (further) comprise secondary redirection optics 540, configured to (a) transmit third device light 131 and optionally fourth device light 141, and reflect second diffused device light 1721, or (b) reflect third device light 131 and optionally fourth device light 141, and transmit second diffused device light 1721; wherein the secondary redirection optics 540 are polarization based; wherein the secondary redirection optics 540 may be configured in the optical path of the third device light 131 and optionally the fourth device light 141 propagating from the second redirection optics 510 to the second diffuser assembly 1720, and wherein the secondary redirection optics 540 may be configured upstream of the light exit 1090, and downstream of the primary redirection optics 535. Further, in embodiments, the light generating system 1000 may be configured such that the third device light 131 and fourth device light 141 reaching the secondary redirection optics 540 comprise the same polarizations, when both the third device light 131 and fourth device light 141 are available.

[0157] Note that when both the third device light 131 and fourth device light 141 are available (see e.g. Fig. 1C), but are not combined via the second redirection optics 510, the optics 500 may comprise (A) secondary redirection optics 540, configured to (a) transmit third device light 131, and reflect second diffused device light 1721, or (b) reflect third device light 131, and transmit second diffused device light 1721, wherein the secondary redirection optics 540 are polarization based; wherein the secondary redirection optics 540 may be configured in the optical path of the third device light 131 propagating from third light generating device 130 to the second diffuser assembly 1720, and wherein the secondary redirection optics 540 may be configured upstream of the light exit 1090, and upstream of the primary redirection optics 535, and (B) tertiary redirection optics 545, configured to (a) transmit fourth device light 141, and reflect third diffused device light 1731, or (b) reflect fourth device light 141, and transmit third diffused device light 1731 (comprising diffused fourth device light); wherein the tertiary redirection optics 545 are polarization based; wherein the tertiary redirection optics 545 may be configured in the optical path of the fourth device light 141 propagating from third light generating device (130) to a third diffuser assembly 1730, and wherein the tertiary redirection optics 545 may be configured upstream of the light exit 1090, and upstream of the secondary redirection optics 540 (which may be configured upstream of the primary redirection optics 535).

[0158] Referring to Figs. 1 A-1D, in embodiments of the light generating system, in the first operational mode of the light generating system 1000 the system light 1001 may white light having a correlated color temperature selected from the range of 2000-9000 K and a color rendering index of at least 65. Further in embodiments the light generating system 1000 further may comprise a control system 300 configured to control a spectral power distribution of the system light 1001 by (individually) controlling the N light generating devices 110,120,130 and optionally also the fourth light generating device 140.

[0159] Referring to Figs. 1 A-1D, in embodiments the system 1000 may comprise an arrangement A2 (of elements), comprising two light generating devices, dichroics based redirection optics to combine the device light of the two light generating devices, a polarization redirection optics configured to split the optical path of the device light of the two light generating devices and the diffused device light, diffused by the diffuser assembly, also comprised by the arrangement A2. In addition, the system may comprise such second arrangement A2 (Fig. Id) or one or more arrangements Al, which may individually comprise a single light generating devices, a polarization redirection optics configured to split the optical path of the device light of the light generating device and the diffused device light, diffused by the diffuser assembly, also comprised by the arrangement Al. In the schematically depicted embodiment of Fig. 1A, a single arrangement Al may comprised by the system 1000, and the schematically depicted embodiment of Fig. 1C, a two arrangements Al may be comprised by the system 1000. The light exit 1090 may be shared by all arrangements (though depicted within the dashed box of (one of the) arrangement(s) A2.

[0160] Fig. 2A shows an emission spectrum of a three-laser based system, wherein the device light of the two different types of laser may be diffused via a first diffuser assembly 1710, and the device light of a third type of lasers may be diffused via a second diffuser assembly 1720.

[0161] Fig. 2B shows an emission spectrum of a three-laser based system, wherein the device light of the two different types of laser may be diffused via a first diffuser assembly 1710, and wherein the laser light of a third type of lasers may at least partly converted by a luminescent material 200 (see the broad emission band as example). The third device light may be not diffused by a second diffuser assembly 1720, see Fig. IB, or may (further) be diffused via a second diffuser assembly, see Fig. 1 A. Note that the third type of laser of which in this embodiment the light may at least partly converted, may differ from the first or the second type of lasers, or may be the same as one of them.

[0162] Fig. 2C shows an emission spectrum of a four-laser based system, wherein the device light of the two different types of laser may be diffused via a first diffuser assembly 1710, and wherein either the device light of a third type of lasers may be diffused via a second diffuser assembly 1720, the device light of a fourth type of laser may be diffused via a third diffuser assembly 1730 (see Fig. 1C), or the device light of a third type of lasers and the fourth type of lasers may be diffused via the second diffuser assembly 1720 (see Fig. ID).

[0163] Fig. 3 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. 3 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. 3 schematically depicts embodiments of a lighting device 1200 selected from the group of a lamp 1, a luminaire 2, a projector device 3, a disinfection device, a photochemical reactor, and an optical wireless communication device, comprising the light generating system 1000 as described herein. In embodiments, such lighting device may be a lamp 1, a luminaire 2, a projector device 3, a disinfection device, or an optical wireless communication device. Lighting device light escaping from the lighting device 1200 is indicated with reference 1201. Lighting device light 1201 may essentially consist of system light 1001, and may in specific embodiments thus be system light 1001. Reference 1300 refers to a space, such as a room. Reference 1305 refers to a floor and reference 1310 to a ceiling; reference 1307 refers to a wall.

[0164] 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. 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. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

[0165] 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.

[0166] 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. The invention also provides a control system that may control the device, apparatus, or system, or that may execute the herein described method or process. Yet further, the invention also provides a computer program product, when running on a computer which is functionally coupled to or comprised by the device, apparatus, or system, controls one or more controllable elements of such device, apparatus, or system. The invention further applies to a device, apparatus, or system comprising one or more of the characterizing features described in the description and / or shown in the attached drawings. The invention further pertains to a method or process comprising one or more of the characterizing features described in the description and / or shown in the attached drawings. 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.

[0167] 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.

[0168] Furthermore, some of the features can form the basis for one or more divisional applications.

Claims

CLAIMS:

1. A light generating system (1000) comprising N light generating devices(110,...), optics (500), M diffuser assemblies (1710,...), and a light exit (1090); wherein: a first light generating device (110) of the N light generating devices (110,...) is configured to generate first device light (111), comprising an emission band having a first emission peak wavelength (Xpi); wherein the first light generating device (110) comprises a first solid state light source (10); wherein the first device light (111) comprises light having a first linear polarization; a second light generating device (120) of the N light generating devices (110,...) is configured to generate second device light (121) comprising an emission band having a second emission peak wavelength (kp2); wherein the second light generating device(120) comprises a second solid state light source (20); wherein the second device light (121) comprises light having the first linear polarization; a third light generating device (130) of the N light generating devices (110,...) is configured to generate third device light (131), comprising an emission band having a third emission peak wavelength (^3); wherein the third light generating device (110) comprises a third solid state light source (30); spectral power distributions of the first device light (111), second device light(121), and third device light (131) mutually differ; the solid state light sources (10,20,30,...) are individually selected from the group comprising laser diodes, superluminescent diodes, and stacked multi -junction lightemitting diodes; a first diffuser assembly (1710) of the M diffuser assemblies (1710,...) comprises a first polarization converter (711) and a reflective polarization maintaining first diffuser (712); wherein the first polarization converter (711) comprises a ’ / retarder with a first wavelength A.ri mof maximum retardance; wherein L-im / 4 is selected from the range of (Xpi / 4 + Zp2 / 4) / 2 ± 5 nm; wherein N>3 and 1<M<N; the optics (500) are configured such that at least part of the first device light (111), and at least part of the second device light (121), received by the optics (500), are directed to the first diffuser assembly (1710);the first diffuser assembly (1710) is configured to diffuse at least part of the first device light (111) and at least part of the second device light (121) received by the first diffuser assembly (1710) into first diffused device light (1711) comprising diffused first device light (111) and diffused second device light (121); the optics (500) are configured such that at least part of the first diffused device light (1711) and the third device light (131) received by the optics (500) are directed to the light exit (1090); the light generating system (1000) is configured to generate system light (1001); wherein in a first operational mode of the light generating system (1000) the system light (1001) is white light comprising the first diffused device light (1711) and the third device light (131); wherein the white light has a correlated color temperature selected from a 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 emission peak wavelength (Xpi), the second emission peak wavelength (Xp2), and third emission peak wavelength (Xp3), are selected from the wavelength ranges of 400-490 nm, 490-590 nm, and 590-690 nm, wherein at least two of the first emission peak wavelength (Xpi), the second emission peak wavelength (Xp2), and third emission peak wavelength (Xp3), are in different wavelength ranges and differ at least 20 nm.

3. The light generating system (1000) according to claim 2, wherein at least one of the following applies: two of the first emission peak wavelength (Xpi), the second emission peak wavelength (Xp2), and third emission peak wavelength (Xp3), are both selected from the wavelength range of 400-490 nm; two of the first emission peak wavelength (Xpi), the second emission peak wavelength (Xp2), and third emission peak wavelength (Xp3), are both selected from the wavelength range of 490-590 nm; two of the first emission peak wavelength (Xpi), the second emission peak wavelength (Xp2), and third emission peak wavelength (Xp3), are both selected from the wavelength range of 590-690 nm; and all three of the first emission peak wavelength (Xpi), the second emission peak wavelength (Xp2), and third emission peak wavelength (Xp3), are each selected from a different wavelength range.

4. The light generating system (1000) according to any one of the preceding claims 1-3, wherein: (i) the first emission peak wavelength (Xpi) and the second emission peak wavelength (Xp2) are both selected from the wavelength range of 400-490 nm, and |Xpi- kp2|> 20 nm; or (ii) the first emission peak wavelength (Xpi) is selected from the wavelength range of 400-490 nm and wherein the second emission peak wavelength (Xp2) is selected from the wavelength range of 490-590 nm, and Xpi-kp2|> 20 nm; or the first emission peak wavelength (Xpi) and the second emission peak wavelength (Xp2) are both selected from the wavelength range of 490-590 nm, and |Xpi-kp2|> 20 nm.

5. The light generating system (1000) according to any one of the preceding claims 1-3, wherein: (i) the first emission peak wavelength (Xpi) is selected from the wavelength range of 490-590 nm and wherein the second emission peak wavelength (Xp2) is selected from the wavelength range of 590-690 nm and pi-Xp2|> 20 nm; or (i) the first emission peak wavelength (Xpi) and the second emission peak wavelength (Xp2) are both selected from the wavelength range of 590-690 nm, and |Xpi-Xp2|> 20 nm.

6. The light generating system (1000) according to any one of the preceding claims, wherein the optics (500) comprise: a first redirection optics (505) comprise dichroic based redirection optics; wherein the first redirection optics (505) is configured to combine the first device light (111) and the second device light (121) and direct the combined first device light (111) and the second device light (121) to the first diffuser assembly (1710); and primary redirection optics (535), configured to (a) transmit first device light (111) and second device light (121), and reflect first diffused device light (1711), or (b) reflect first device light (111) and second device light 121), and transmit first diffused device light (1711); wherein the primary redirection optics (535) are polarization based; wherein the light generating system (1000) is configured such that the first device light (111) and second device light (121) reaching the primary redirection optics (535) comprise the same polarizations; wherein the primary redirection optics (535) is configured in the optical path of the first device light (111) and the second device light (121) propagating from the first redirection optics (505) to the first diffuser assembly (1710), and wherein the primary redirection optics (535) is configured upstream of the light exit (1090).

7. The light generating system (1000) according to any one of the preceding claims, comprising a second diffuser assembly (1720); wherein the second diffuser assembly (1720) comprises a second diffuser (722); wherein: the third emission peak wavelength (Xp3) differs with at least 20 nm from the first emission peak wavelength (Xpi) and differs with at least 20 nm from the second emission peak wavelength (kp2); the optics (500) are configured such that at least part of the third device light (131), received by the optics (500), is directed to the second diffuser assembly (1720); the second diffuser assembly (1720) is configured to diffuse at least part of the third device light (131) received by the second diffuser assembly (1720) into second diffused device light (1721) comprising diffused third device light (131); the optics (500) are configured such that at least part of the second diffused device light (1721) received by the optics (500) is directed to the light exit (1090); and in the first operational mode of the light generating system (1000) the system light (1001) is white light comprising the first diffused device light (1711) and the second diffused device light (1721).

8. The light generating system (1000) according to claim 7, wherein: the third solid state light source (30) is configured to generate third light source light (31); and wherein at least 80% of the spectral power of the third device light (131) in the visible wavelength range consists of third light source light (31); and the second diffuser assembly (1720) comprises a second polarization converter (721); wherein the second diffuser (722) comprises a reflective polarization maintaining second diffuser; and wherein the third device light (131) comprises light having a third linear polarization.

9. The light generating system (1000) according to any one of the preceding claims, comprising a fourth light generating device (140); wherein the fourth light generating device (140) of the N light generating devices (110,...), is configured to generate fourth device light (141), comprising an emission band having a fourth emission peak wavelength (Xp4); wherein the fourth light generating device (140) comprises a fourth solid state light source (40); wherein |Zpi-kp3|> 20 nm, |Zp2-kp3|> 20 nm, |Zpi-kp4|> 20 nm, |Zp2-kp4|> 20 nm, and |kp3-kp4|> 20 nm, applies.

10. The light generating system (1000) according to claims 8-9, wherein: the fourth device light (141) comprises light having the third linear polarization; the second polarization converter (721) comprises a ’ / retarder with a second wavelength A.r2m of maximum retardance; wherein A.r2m / 4 is selected from the range of (Xps / 4 + Xp4 / 4) / 2 ± 5 nm; the optics (500) are configured such that at least part of the fourth device light (141), received by the optics (500), is directed to the second diffuser assembly (1720); and the second diffuser assembly (1720) is configured to diffuse at least part of the third device light (131) and the fourth device light (131) received by the second diffuser assembly (1720) into the second diffused device light (1721) comprising the diffused third device light (131) and diffused fourth device light (141).

11. The light generating system (1000) according to any one of the preceding claims 9-10, wherein the optics (500) comprise: second redirection optics (510) comprises dichroic based redirection optics; wherein the second redirection optics (510) is configured to combine the third device light (131) and the fourth device light (141) and direct combined third device light (131) and the fourth device light (141) to the second diffuser assembly (1720); and secondary redirection optics (540), configured to (a) transmit third device light (131) and fourth device light (141), and reflect second diffused device light (1721), or (b) reflect third device light (131) and second device light (121), and transmit second diffused device light (1721); wherein the secondary redirection optics (540) are polarization based; wherein the light generating system (1000) is configured such that the third device light (131) and fourth device light (141) reaching the secondary redirection optics (540) comprise the same polarizations; wherein the secondary redirection optics (540) is configured in the optical path of the third device light (131) and the fourth device light (141) propagating from the second redirection optics (510) to the second diffuser assembly (1720), and wherein the secondary redirection optics (540) is configured upstream of the light exit (1090), and downstream of the primary redirection optics (535).

12. The light generating system (1000) according to any one of the preceding claims 9-11, wherein the first emission peak wavelength (Xpi) and the second emission peak wavelength (Xp2) are both selected from the wavelength range of 400-560 nm, and wherein| Xpi-Xp2|> 20 nm; wherein the third emission peak wavelength (Xps) and the fourth emission peak wavelength (Xp4) are both selected from the wavelength range of 560-750 nm, and wherein |Zp3-kp4|> 20 nm.

13. The light generating system (1000) according to any one of the preceding claims, wherein each of the first, second, third, and optionally fourth solid state light sources (10,20,30,...) comprise laser diodes; wherein the light generating system (1000) comprises one or more laser banks (5), wherein the laser banks (5) comprise a light emitting arrangement comprising a 2D array of a plurality of laser diodes arranged on a thermally conductive carrier and a lens array having a plurality of collimator lenses corresponding to the laser diodes such that each laser diode of the plurality of laser diodes comprises a collimator lens for collimating laser light emitted by the laser diode.

14. The light generating system (1000) according to any one of the preceding claims, wherein in the first operational mode of the light generating system (1000) the system light (1001) is white light having a correlated color temperature selected from the range of 2000-9000 K and a color rendering index of at least 70; wherein the light generating system (1000) further comprises a control system (300) configured to control a spectral power distribution of the system light (1001) by individually controlling the N light generating devices (110,...).

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

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