A light generating system

Abstract

A light generating system (1) configured to, in operation, emit system light (2) and comprising at least one first solid state light source (3) configured to, in operation, emit first light source light (4), a first collimating optical element (5) arranged and configured to collimate the first light source light (4) into a beam of first collimated light source light (6), a luminescent element (7) being arranged downstream of the first solid state light source, the luminescent element comprising a first major surface (71) and a second major surface (72) opposite to the first major surface, and a first light redirecting optical element (8) being arranged in front of and centered with respect to the luminescent element (7). The first light redirecting optical element (8) is a specular reflector comprising specularly reflecting surfaces (82-85) configured to receive the beam of the first collimated light source light (6), and redirect it onto the first major surface (71) of the luminescent element (7) such that a first main optical axis (A1) of the beam of the first collimated light source light (6) propagating from the first light redirecting optical element (8) towards the luminescent element (7) forms a first angle (α1) with respect to a normal (B) to the first major surface (71) of the luminescent element (7), wherein the first angle (α1) fulfills 3 degrees ≤ α1 ≤ 15 degrees.

Description

[0001] 2025PF80029

[0002] 1

[0003] A LIGHT GENERATING SYSTEM

[0004] FIELD OF THE INVENTION

[0005] The invention relates to a light generating system configured to, in operation, emit system light. The invention further relates to a lamp or a luminaire comprising such a light generating system.

[0006] As used herein, the term “violet light” is intended to refer to light with a peak wavelength falling within the wavelength interval of 380 nm to 420 nm.

[0007] As used herein, the term “blue light” is intended to refer to light with a peak wavelength falling within the wavelength interval of 420 nm to 490 nm.

[0008] As used herein, the term “green-yellow light” is intended to refer to light with a peak wavelength falling within the wavelength interval of 500 nm to 590 nm.

[0009] As used herein, the term “green light” is intended to refer to light with a peak wavelength falling within the wavelength interval of 500 nm to 550 nm.

[0010] As used herein, the term “yellow light” is intended to refer to light with a peak wavelength falling within the wavelength interval of 550 nm to 590 nm.

[0011] As used herein, the term “yellow-orange light” is intended to refer to light with a peak wavelength falling within the wavelength interval of 550 nm to 600 nm.

[0012] As used herein, the term “red light” is intended to refer to light with a peak wavelength falling within the wavelength interval of 600 nm to 680 nm.

[0013] As used herein, the term “white light” is intended to refer to light with correlated color temperature falling within the color temperature range of 2000 K to 9000 K, preferably in a correlated color temperature range of 2700 K to 6500 K.

[0014] As used herein, the term “cool white light” is intended to refer to light with correlated color temperature falling within the color temperature range of 3500 K to 6500 K.

[0015] As used herein, the term “extreme cool white light” is intended to refer to light with correlated color temperature falling within the color temperature range of 6500 K to 9000 K.

[0016] As used herein, the term “warm white light” is intended to refer to light with correlated color temperature falling within the color temperature range of 2000 K to 3500 K.2025PF80029

[0017] 2

[0018] As used herein, the terms “upstream” and “downstream” are intended to be understood relative to the direction of propagation of light through the light generating system. In other words, when a first component or feature is arranged “downstream” of a second component or feature, it may be understood that the first component or feature is arranged in a light receiving relationship with the second component or feature.

[0019] As used herein, the term “first solid state light source” is intended to refer to any first solid state light source, including LEDs as well as diode lasers, super-luminescent diodes, and multi -junction diodes, comprising one or more LEDs.

[0020] As used herein, the term “major part of X” is intended to denote at least 60 %, at least 80 % or at least 90 % of X, where X for instance may be a type of light propagating in or generated by the light generating system.

[0021] BACKGROUND OF THE INVENTION

[0022] Laser-phosphor technology is used in high-end lighting applications such as automotive headlights, projection, and stage-lighting. Recent advancements have simplified and miniaturized the technology such that it can also be used in other lighting applications such as spotlights and flashlights. While applications such as projectors and stage-lighting need an expensive, complex, and bulky laser-phosphor engine architecture, recent commercially available laser excited phosphor (LEP) flashlights show the engine architecture can be compact, low-cost, safe, and simple.

[0023] US 9,920,902 B2 discloses a laser source which is configured for providing collimated laser beams arranged in a ring-shape for exiting a phosphor. The laser source has laser diodes arranged in a ring-shaped manner around a symmetry axis. Parallel parts of the laser beams form a hollow tube. Further, a light source is described. The light source has a phosphor, an optical element and a light source configured for providing collimated laser beams arranged in a ring-shape for exiting the phosphor. The light source is arranged such that the collimated laser beams are directed opposite to the collimated luminance.

[0024] However, the optical performance, such as color over angle, and / or the functionality of the known light generating systems is too low for general lighting applications. Therefore, it is desired to improve the optical performance, such as color over angle, and / or the functionality of light generating systems configured to, in operation, emit system light.2025PF80029

[0025] 3

[0026] SUMMARY OF THE INVENTION

[0027] It is an object of the present invention to overcome this problem, and to provide a light generating system configured to, in operation, emit system light, the light generating system being provided with one or more of an improved optical performance, such as color over angle, and an improved functionality.

[0028] According to a first aspect of the invention, this and other objects are achieved by means of a light generating system configured to, in operation, emit system light, the light generating system comprising: at least one first solid state light source configured to, in operation, emit first light source light having a first peak emission wavelength, VI , being in a wavelength range of 430 nm to 490 nm, the at least one first solid state light source comprising one or more of a laser diode, a super-luminescent diode, and a stacked multijunction light-emitting diode, a first collimating optical element arranged downstream of the at least one first solid state light source and configured to collimate the first light source light into a beam of first collimated light source light, a luminescent element being arranged downstream of the first solid state light source, the luminescent element comprising a first major surface and a second major surface opposite to the first major surface, and a first light redirecting optical element being arranged in front of and centered with respect to the luminescent element, wherein the first light redirecting optical element is a specular reflector comprising a plurality of specularly reflecting surfaces configured to (i) receive the beam of the first collimated light source light, and (ii) redirect the beam of the first collimated light source light onto the first major surface of the luminescent element such that a first main optical axis, Al, of the beam of the first collimated light source light propagating from the first light redirecting optical element towards the luminescent element forms a first angle, al, with respect to a normal, B, to the first major surface of the luminescent element, wherein the first angle, al, fulfills 3 degrees < al < 15 degrees, wherein the luminescent element is configured to convert a part of the first collimated light source light into first converted light having a second peak emission wavelength, 2, being in a wavelength range of 500 nm to 590 nm, and wherein the luminescent element further is configured to reflect part of the collimated light source light as first reflected light, wherein the light generating system further comprises a first collimator arranged downstream of the luminescent element and configured to collimate the first reflected light and the first converted light, and wherein the system light comprises, in an operational mode, a combination of the first reflected light and the first converted light, and the system light is white light having a correlated color temperature in a range from 2000 K to 9000 K and a color rendering index of at least 65.2025PF80029

[0029] 4

[0030] Thereby, a light generating system configured to, in operation, emit system light and being provided with one or more of an improved optical performance, such as color over angle, and an improved functionality is provided for.

[0031] The first peak emission wavelength, I, may be in a wavelength range of 435 nm to 480 nm, or a wavelength range of 440 nm to 475 nm, or a wavelength range of 445 nm to 470 nm, or a wavelength range of 450 nm to 465 nm.

[0032] The at least one first solid state light source may be a laser bank comprising an array of a plurality of laser diodes.

[0033] The first collimating element may be one or more lenses.

[0034] The second peak emission wavelength, X2, may be in a wavelength range of 510 nm to 580 nm, or a wavelength range of 515 nm to 570 nm, or a wavelength range of 518 nm to 560 nm, or a wavelength range of 520 nm to 550 nm.

[0035] The angle, al, may fulfill 4 degrees < al < 14 degrees or 5 degrees < al < 13 degrees.

[0036] Thereby, a light generating system with one or more of a particularly improved optical performance, such as color over angle, and a particularly improved functionality is provided for.

[0037] The at least one first solid state light source may further be configured to emit second light source light having a third peak emission wavelength, X3, being in a wavelength range of 600 nm to 680 nm.

[0038] Thereby, a light generating system with a further improved optical performance, especially in terms of light quality, is provided for.

[0039] The third peak emission wavelength, X3, may be in a wavelength range of 605 nm to 670 nm, or a wavelength range of 610 nm to 660 nm, or a wavelength range of 615 nm to 650 nm, or a wavelength range of 620 nm to 645 nm.

[0040] The light generating system may further comprise at least one second solid state light source configured to, in operation, emit third light source light having a fourth peak emission wavelength, X4, being in a wavelength range from 430 nm to 490 nm, the at least one second solid state light source comprising one or more of a laser diode, a super-luminescent diode, and a stacked multi -junction light-emitting diode, and a second collimating optical element arranged downstream of the at least one second solid state light source and configured to collimate the third light source light into a beam of second collimated light source light, wherein the plurality of specularly reflecting surfaces of the first light redirecting optical element further is configured to (iii) receive the beam of second2025PF80029

[0041] 5

[0042] collimated light source light, and (iv) redirect the beam of second collimated light source light onto the first major surface of the luminescent element such that a second main optical axis, A2, of the beam of second collimated light source light propagating from the first light redirecting optical element towards the luminescent element form a second angle, a2, with respect to a normal, B, to the first major surface of the luminescent element, wherein the second angle, a2, fulfills 3 degrees < a2 < 15 degrees, wherein the beam of first collimated light source light and the beam of second collimated light source light propagate towards the luminescent element from mutually different directions, wherein the luminescent element further is configured to convert a part of the second collimated light source light into second converted light having a fifth peak emission wavelength, 5, being in a wavelength range of 500 nm to 590 nm, and wherein the luminescent element further is configured to reflect part of the second collimated light source light as second reflected light, wherein the first collimator is further configured to collimate the second reflected light and the second converted light, and wherein the system light further comprises, in an operational mode, the second reflected light and the second converted light.

[0043] Thereby, a light generating system with one or more of a further improved optical performance, such as color over angle, and a further improved functionality is provided for.

[0044] The fourth peak emission wavelength, X4, may be in a wavelength range of 435 nm to 480 nm, or a wavelength range of 440 nm to 475 nm, or a wavelength range of 445 nm to 470 nm, or a wavelength range of 450 nm to 465 nm.

[0045] The fifth peak emission wavelength, 5, may be in a wavelength range of 510 nm to 580 nm, or a wavelength range of 515 nm to 570 nm, or a wavelength range of 518 nm to 560 nm, or a wavelength range of 520 nm to 550 nm.

[0046] The angle, a2, may fulfill 4 degrees < al < 14 degrees or 5 degrees < al < 13 degrees.

[0047] Thereby, a light generating system with one or more of a particularly improved optical performance, such as color over angle, and a particularly improved functionality is provided for.

[0048] The first collimated light source light forms a first spot on the first major surface of the luminescent element, and the second collimated light source light forms a second spot on the first major surface of the luminescent element, wherein the first spot and the second spot may form an overlap being at least 70 % defined by the full width at half2025PF80029

[0049] 6

[0050] maximum, FWHM, or measured at the FWHM of the first and second collimated light source light at the fires major surface, respectively.

[0051] Thereby, the first collimated light source light and the second collimated light source light may be combined in a simple manner.

[0052] The first spot and the second spot may form an overlap being at least 75%, or at least 80%, or at least 85%, such as at least 90%, or at least 95%, defined by the full width at half maximum, FWHM, or measured at the FWHM of the first and second collimated light source light at the fires major surface, respectively.

[0053] The beam of first collimated light source light may be reflected by a first specularly reflecting surface of the plurality of specularly reflecting surfaces such that an angle, 1, between the first main optical axis, Al, and the first specularly reflecting surface of the plurality of specularly reflecting surfaces fulfills 48 degrees < 01 < 60 degrees.

[0054] The angle, 01, may fulfil 50 degrees < 01 < 58 degrees, 51 degrees < 01 < 57 degrees, or 52 degrees < 01 < 56 degrees.

[0055] When a second solid state light source is provided, the beam of second collimated light source light may be reflected by a second specularly reflecting surface of the plurality of specularly reflecting surfaces such that an angle, P2, between the second main optical axis, A2, and the second specularly reflecting surface of the plurality of specularly reflecting surfaces fulfills 48 degrees < 02 < 60 degrees, wherein the first specularly reflecting surface is different from the second specularly reflecting surface.

[0056] The angle, P2, may fulfil 50 degrees < 02 < 58 degrees, 51 degrees < 02 < 57 degrees, or 52 degrees < 02 < 56 degrees.

[0057] Thereby, a light generating system with one or more of a further improved optical performance, such as color over angle, and a further improved functionality is provided for.

[0058] The first light redirecting optical element further comprises a base from which the plurality of specularly reflecting surfaces extend, wherein the plurality of specularly reflecting surfaces may form an angle, y, with respect to the base, wherein the angle, y, fulfills 60 degrees < y < 66 degrees.

[0059] The angle, y, may fulfill 61 degrees < y < 66 degrees, or 60 degrees < y < 65 degrees.

[0060] Thereby, a particularly simple first light redirecting optical element is provided for with which a light generating system with one or more of a further improved2025PF80029

[0061] 7

[0062] optical performance, such as color over angle, and a further improved functionality may be obtained.

[0063] The beam of first collimated light source light may be directed to a first specularly reflecting surface of the plurality of specularly reflecting surfaces with a third main optical axis, DI, extending in an angle, 51, with an axis, E, the axis, E, extending perpendicular to the normal, B, to the first major surface of the luminescent element, wherein the angle, 51, fulfills 0 degrees < 51 < 20 degrees, or 0 degrees < 51 < 15 degrees, or 0 degrees < 51 < 10 degrees.

[0064] When a second solid state light source (33) is provided, the beam of second collimated light source light may be directed to a second specularly reflecting surface of the plurality of specularly reflecting surfaces with a fourth main optical axis, D2, extending in an angle, 52, with the axis, E, the axis, E, extending perpendicular to the normal, B, to the first major surface of the luminescent element, wherein the angle, 52, fulfills 0 degrees < 52 < 20 degrees, or 0 degrees < 52 < 15 degrees, or 0 degrees < 52 < 10 degrees.

[0065] Thereby, a light generating system with one or more of a further improved optical performance, such as color over angle, and a further improved functionality is provided for.

[0066] The light generating system may further comprise at least one third solid state light source configured to, in operation, emit fourth light source light having a sixth peak emission wavelength, <6, being in a wavelength range from 430 nm to 490 nm, the at least one third solid state light source comprising one or more of a laser diode, a super-luminescent diode, and a stacked multi -junction light-emitting diode, and a third collimating optical element arranged downstream of the at least one third solid state light source and configured to collimate the fourth light source light into a beam of third collimated light source light, wherein the plurality of specularly reflecting surfaces of the first light redirecting optical element further is configured to (v) receive the beam of third collimated light source light, and (vi) redirect the beam of third collimated light source light onto the first major surface of the luminescent element such that a fifth main optical axis, A3, of the beam of third collimated light source light propagating from the first light redirecting optical element towards the luminescent element form a third angle, a3, with respect to a normal, B, to the first major surface of the luminescent element, wherein the third angle, a3, fulfills 3 degrees < a3 < 15 degrees, wherein the beam of first collimated light source light, the beam of second collimated light source light, and the beam of third collimated light source light propagate towards the luminescent element from mutually different directions, wherein the luminescent2025PF80029

[0067] 8

[0068] element further is configured to convert a part of the beam of third collimated light source light into third converted light having a seventh peak emission wavelength, 7, being in a wavelength range of 500 nm to 590 nm, and wherein the luminescent element further is configured to reflect part of the third collimated light source light as third reflected light, wherein the first collimator further is configured to collimate the third reflected light and the third converted light, and wherein the system light further comprises, in an operational mode, the third reflected light and the third converted light.

[0069] Thereby, a light generating system with one or more of a further improved optical performance, such as color over angle, and a further improved functionality is provided for.

[0070] The sixth peak emission wavelength, Z6, may be in a wavelength range of 435 nm to 480 nm, or a wavelength range of 440 nm to 475 nm, or a wavelength range of 445 nm to 470 nm, or a wavelength range of 450 nm to 465 nm.

[0071] The seventh peak emission wavelength, 7, may be in a wavelength range of 510 nm to 580 nm, or a wavelength range of 515 nm to 570 nm, or a wavelength range of 518 nm to 560 nm, or a wavelength range of 520 nm to 550 nm.

[0072] The angle, a3, may fulfill 4 degrees < al < 14 degrees or 5 degrees < al < 13 degrees.

[0073] Thereby, a light generating system with one or more of a particularly improved optical performance, such as color over angle, and a particularly improved functionality is provided for.

[0074] The light generating system comprises N solid state light sources, and the plurality of specularly reflecting surfaces comprises M specularly reflecting surfaces, wherein M and N may be chosen such that M > 4 and N > 4, or M > 5 and N > 5, or M > 6 and N > 6.

[0075] Thereby, a light generating system with one or more of an even further improved optical performance, such as color over angle, and an even further improved functionality is provided for.

[0076] The first light redirecting optical element comprises a base from which the plurality of specularly reflecting surfaces extend, the base comprising a length, L, and a width, W, wherein each of the length, L, and the width, W, may be < 7 mm or < 5 mm.

[0077] The first light redirecting optical element comprises a base from which the plurality of specularly reflecting surfaces extend, the base comprising a length, L, and a width, W, wherein each of the length, L, and the width, W, may be less than or equal to 1 / 102025PF80029

[0078] 9

[0079] or 1 / 5 of a diameter, H, of the collimator, or an equivalent to the diameter, H, of the collimator.

[0080] Thereby, a small yet efficient first light redirecting optical element is provided for, which in turn ensures that the influence of the first light redirecting optical element on the light propagating away from the luminescent element, and thus on the device light, is reduced or minimized.

[0081] The first light redirecting optical element may have a volume being smaller than 5 mm x 5 mm x 5 mm, or a volume being smaller than 3 mm x 3 mm x 3 mm.

[0082] The at least one first solid state light source may be arranged at a side of the luminescent element opposite to the first light redirecting optical element and offset to a first side of the luminescent element.

[0083] Where provided, the at least one second solid state light source may be arranged at a side of the luminescent element opposite to the first light redirecting optical element and offset to a second side of the luminescent element. The second side may be different from the first side.

[0084] Where provided, the at least one third solid state light source may be arranged at a side of the luminescent element opposite to the first light redirecting optical element and offset to a third side of the luminescent element. The third side may be different from the first side and the second side.

[0085] A first reflecting element may be arranged downstream of the first collimating element and configured to direct the first collimated light source light to the first light redirecting optical element.

[0086] Where a second light source is provided, a second reflecting element may be arranged downstream of the second collimating element and configured to direct the second collimated light source light to the first light redirecting optical element.

[0087] Where a third light source is provided, a third reflecting element is arranged downstream of the third collimating element and configured to direct the third collimated light source light to the first light redirecting optical element.

[0088] Providing one or more of a first reflecting element, a second reflecting element and a third reflecting element ensures that as little interference between the light propagating towards the luminescent element and the light propagating away from the luminescent element as possible occurs while still enabling achieving the above advantages.

[0089] The at least one first solid state light source may be a canned first solid state light source.2025PF80029

[0090] 10

[0091] Where provided, the at least one second solid state light source may be a canned second solid state light source.

[0092] Where provided, the at least one third solid state light source may be a canned third solid state light source.

[0093] Thereby, a more robust light generating device is provided for since canned solid state light source(s) are better protected against external influences as compared to noncanned solid state light sources.

[0094] The first light redirecting optical element may be V-shaped or pyramidshaped.

[0095] Thereby a simple and efficient first light redirecting optical element is provided for.

[0096] A major part of the first converted light and a major part of the first reflected light does not impinge onto the first light redirecting optical element.

[0097] Where at least one second solid state light source is provided, a major part of the second converted light and a major part of the second reflected light does not impinge onto the first light redirecting optical element.

[0098] Where at least one third solid state light source is provided, a major part of the third converted light and a major part of the third reflected light does not impinge onto the first light redirecting optical element.

[0099] Thereby, the influence of the first light redirecting optical element on the light propagating away from the luminescent element, and thus on the device light, is minimized.

[0100] The first light redirecting optical element may be mounted on a transparent substrate.

[0101] Mounting the first light redirecting optical element on a substrate enables ensuring that the first light redirecting optical element is kept in position in a stable manner without exerting any influence on the plurality of specularly reflecting surfaces of the first light redirecting optical element. Making the substrate transparent ensures that the substrate has little or no influence on the device light.

[0102] The light generating system may further comprise a controller configured to individually control the at least one first solid state light source, where provided, the at least one second solid state light source, and, where provided, the at least one third solid state light source.

[0103] The light generating system may further comprise a sensor configured to sense an operational parameter of the light generating system and to provide the sensed operational2025PF80029

[0104] 11

[0105] parameter to the controller. The controller may then further be configured to individually control the first solid state light source, where provided, the at least one second solid state light source, and, where provided, the at least one third solid state light source, based on the sensed operational parameter.

[0106] Thereby, it becomes possible to adapt the obtained device light to various different applications and to the light requirements thereof. For instance, it becomes possible to control the light generating system to emit either spotlight, for instance for visualizing objects, or flood light, for instance for orientation. It also becomes possible to control the flood-spot light ratio. Furthermore, it becomes possible to control the correlated color temperature, CCT, and the color rendering index, CRI of the device light.

[0107] The light generating system may further comprise at least one beam-dump arranged and configured to absorb (i) first collimated light source light, (ii) where a second solid state light source is provided, second collimated light source light, and (iii), where a third solid state light source is provided, third collimated light source light, which in case the first light redirecting optical element is removed would escape the light generating system.

[0108] The at least one beam dump may be ring shaped.

[0109] Thereby, a light generating system with an increased and improved safety is provided for.

[0110] The light generating system may further comprise an optical element arranged downstream of the collimator, wherein the optical element is a transparent optical element for the first reflected light and the first converted light, where a second solid state light source is provided, for the second reflected light and the second converted light, and where a third solid state light source is provided, for the third reflected light and the third converted light. Alternatively, the optical element may be a diffusing element configured to diffuse the system light.

[0111] Such an optical element serves at least one of two purposes, namely to close off the housing from the surroundings such as to protect the optical components from external influences, and to enhance the light quality of the device light even further.

[0112] The luminescent element may further be configured to reflect and diffuse a part of the first collimated light source light, and, where a second solid state light source is provided, a part of the second collimated light source light, and, where a third solid state light source is provided, a part of the third collimated light source light.

[0113] Thereby, the device light may also be or comprise diffuse light, which in turn enables more homogeneous device light.2025PF80029

[0114] 12

[0115] The first collimated light source light may comprise P light source light beams, wherein the respective main axes of the P light source light beams are mutually parallel, or wherein the respective main axes of the P light source light beams extend in an angle of less than 20 degrees, less than 15 degrees, or less than 10 degrees with the first or second main optical axis, Al or DI, of the first collimated light source light.

[0116] Where at least one second solid state light source is provided, the second collimated light source light may comprise Q light source light beams, wherein the respective main axes of the Q light source light beams are mutually parallel, or wherein the respective main axes of the Q light source light beams extend in an angle of less than 20 degrees, less than 15 degrees, or less than 10 degrees with the third or fourth main optical axis, A2 or D2, of the second collimated light source light.

[0117] Where at least one third solid state light source is provided, the third collimated light source light may comprise R light source light beams, wherein the respective main axes of the R light source light beams are mutually parallel, or wherein the respective main axes of the R light source light beams extend in an angle of less than 20 degrees, less than 15 degrees, or less than 10 degrees with the fourth or a fifth main optical axis, A3 or D3, of the second collimated light source light.

[0118] The invention further relates to a lamp or a luminaire, or a vehicle light, or a projection device, or a search light, or a flashlight, or a stage lighting device comprising a light generating system according to the invention.

[0119] The lamp or the luminaire - or the vehicle light, or the projection device, or the search light, or the stage lighting device - may, thanks to the light generating system, provide system light with an improved brightness and / or an improved color quality.

[0120] The lamp or luminaire may be any type of lamp and luminaire, but particularly a vehicle light, or a projection device, or a search light, or a flashlight, or a stage lighting device.

[0121] It is noted that the invention relates to all possible combinations of features recited in the claims.

[0122] BRIEF DESCRIPTION OF THE DRAWINGS

[0123] This and other aspects of the present invention will now be described in more detail, with reference to the appended drawings showing embodiment(s) of the invention.

[0124] Fig. 1 shows a schematical side view of a light generating system according to the invention seen from a first angle of view and comprising a first solid state light source, a2025PF80029

[0125] 13

[0126] first collimating optical element, a luminescent element, and a first light redirecting optical element.

[0127] Fig. 2 shows a schematical side view of another light generating system according to the invention and seen from the first angle of view.

[0128] Fig. 3 shows a schematical side view of the light generating system according to Fig. 2 and seen from a second angle of view being perpendicular to the first angle of view.

[0129] Fig. 4 schematically shows collimated light source light incident on the luminescent element of a light generating system according to Fig. 1 or 2.

[0130] Fig. 5 schematically shows collimated light source light incident on the luminescent element of a light generating system according to Fig. 2 or 3.

[0131] Fig. 6 schematically shows collimated light source light incident on the luminescent element of a light generating system according to Fig. 2.

[0132] Fig. 7 schematically shows collimated light source light incident on the luminescent element of a light generating system according to Fig. 2.

[0133] Fig. 8 schematically shows an exemplary first light redirecting optical element of a light generating system according to the invention.

[0134] Fig. 9 shows a graph illustrating the reflectance from the surface of an exemplary luminescent element comprising a luminescent material being a Yttrium Aluminum Garnet (YAG) phosphor as a function of the angle of incidence for light of two different polarizations.

[0135] Fig. 10 shows a graph illustrating the intensity of (i) the reflected light when the light is incident at an angle of 10 degrees and 20 degrees, respectively, to the surface of an exemplary luminescent element comprising a luminescent material being a Yttrium Aluminum Garnet (YAG) phosphor, and (ii) the phosphor light emitted from the same luminescent element, as a function of the angle of incidence.

[0136] Fig. 11 shows a graph of the intensity in arbitrary units as a function of the wavelength of emission (Em; solid line) and excitation (Ex; dashed line), respectively, for a YAG phosphor.

[0137] Fig. 12 shows a schematical side view of a lamp comprising a light generating system according to the invention.

[0138] Fig. 13 shows a schematical side view of a luminaire comprising a lamp and a light generating system according to the invention.

[0139] As illustrated in the figures, the sizes of layers and regions are exaggerated for illustrative purposes and, thus, are provided to illustrate the general structures of2025PF80029

[0140] 14

[0141] embodiments of the present invention. Like reference numerals refer to like elements throughout.

[0142] DETAILED DESCRIPTION

[0143] The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which currently preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness, and fully convey the scope of the invention to the skilled person.

[0144] Fig. 1 shows a schematical side view of a light generating system 1 according to the invention. Generally, and irrespective of the embodiment, the light generating system 1 comprises a first solid state light source 3, a first collimating optical element 5, a luminescent element 7, and a first light redirecting optical element 8. The light generating system 1 is configured to, in operation, emit system light 2.

[0145] The first solid state light source 3 is configured to, in operation, emit first light source light 4. The first light source light 4 comprises a first peak emission wavelength, I, being in a wavelength range of 430 nm to 490 nm. The first solid state light source 3 comprises one or more of a laser diode, a super-luminescent diode, and a stacked multijunction light-emitting diode. It is feasible that more than one first solid state light source 3 may be provided. The first solid state light source 3 may further be configured to emit second light source light 4’ having a third peak emission wavelength, X3, being in a wavelength range of 600 nm to 680 nm. The first solid state light source 3 may be a canned first solid state light source.

[0146] The first collimating optical element 5 is arranged downstream of the first solid state light source 3. The first collimating optical element 5 is configured to collimate the first light source light 4 and optionally 4’ into a beam of first collimated light source light 6. The first collimating optical element 5 may for instance be a lens or a lens system, e.g., a plurality of lenses.

[0147] The luminescent element 7 is arranged downstream of the first solid state light source 3. The luminescent element 7 comprises a first major surface 71 and a second major surface 72 opposite to the first major surface. The luminescent element 7 is arranged and configured to receive the collimated light source light 6. The luminescent element 7 is configured to convert a part of the first collimated light source light 6 into first converted2025PF80029

[0148] 15

[0149] light 10. The first converted light 10 comprises a second peak emission wavelength, X2, being in a wavelength range of 500 nm to 590 nm. The luminescent element 7 is further configured to reflect a part of the collimated light source light 6 as first reflected light 6’. A major part of the first converted light 10 and a major part of the first reflected light 6’, such as at least 60 %, at least 80 % or at least 90 % of the first converted light 10 and the first reflected light 6’, respectively, does not impinge onto the first light redirecting optical element 8. The luminescent element 7 may further optionally be configured to reflect and diffuse a part of the first collimated light source light 6, such as to provide first reflected and diffused light 6’.

[0150] The luminescent element 7 may be arranged on a substrate 11, cf. Figs. 4-7. The substrate 11 may be a heat sink configured to lead heat away from the luminescent element 7. Also, a housing 22 (cf. Fig. 1) of the luminescent element 1 may be configured to form a heat sink such as to further improve the cooling of the luminescent element 7 and / or such as to lead away heat from and thus cool the first solid state light source 3.

[0151] The first light redirecting optical element 8 is arranged in front of and centered with respect to the luminescent element 7. The first light redirecting optical element 8 is a specular reflector. The first light redirecting optical element 8 comprises a plurality of specularly reflecting surfaces 82-85. The first light redirecting optical element 8 is configured to, at a surface of the plurality of specularly reflecting surfaces 82-85, receive the beam of the first collimated light source light 6. The first light redirecting optical element 8 is further configured to redirect the beam of first collimated light source light 6 onto the first major surface 71 of the luminescent element 7 such that a first main optical axis Al of the beam of first collimated light source light 6 propagating from the first light redirecting optical element 8 towards the luminescent element 7 forms a first angle al with respect to a normal B to the first major surface 71 of the luminescent element 7 - cf. Fig. 4. The first angle al may fulfill 3 degrees < al < 15 degrees.

[0152] Referring to Fig. 6, the beam of first collimated light source light 6 is reflected by a first specularly reflecting surface 82 of the plurality of specularly reflecting surfaces 82-85 such that an angle P 1 is formed between the first main optical axis Al and the first specularly reflecting surface 82 of the plurality of specularly reflecting surfaces 82-85. The angle pi fulfills 48 degrees < pi < 60 degrees.

[0153] Referring still to Fig. 6, the first light redirecting optical element 8 further comprises a base 81. The plurality of specularly reflecting surfaces 82-85 extend from the base 81. The plurality of specularly reflecting surfaces 82-85 form an angle y with respect to the base 81. The angle y fulfills 60 degrees < y < 66 degrees.2025PF80029

[0154] 16

[0155] Referring now to Fig. 7, the beam of first collimated light source light 6 is directed to the first specularly reflecting surface 82 of the plurality of specularly reflecting surfaces 82-85 with a third main optical axis DI extending in an angle 51 with an axis E extending perpendicular to the normal B to the first major surface 71 of the luminescent element 7. The angle 51 fulfills 0 degrees < 51 < 20 degrees, or 0 degrees < 51 < 15 degrees, or 0 degrees < 51 < 10 degrees.

[0156] It is noted that in principle only one of the above-described conditions relating to the angle y and the angle 51, respectively, need to be fulfilled.

[0157] The system light 2 thus comprises, in an operational mode, a combination of the first reflected light 6’ and the first converted light 10. The system light is white light having a correlated color temperature in a range from 2000 K to 9000 K and a color rendering index of at least 65.

[0158] The light generating system 1 further comprises a first collimator 12. The first collimator 12 is arranged downstream of the luminescent element 7. The first collimator 12 is configured to collimate the first reflected light 6’ and the first converted light 10. In other words, the first collimator 12 is configured to collimate the system light 2.

[0159] The first solid state light source 3 may as shown in Fig. 1 be arranged behind and to a first side 16 of the luminescent element 7. The first solid state light source 3 and the first light redirecting element 8 may be arranged at mutually opposite sides of the luminescent element 7. The first solid state light source 3 may be arranged offset to the first side 16 of the luminescent element 7.

[0160] An optional first reflecting element 9 may be arranged downstream of the first collimating element 5. The first reflecting element 9 is configured to direct the beam of first collimated light source light 6 to the first light redirecting optical element 8.

[0161] The light generating system 1 further comprises an optional controller 20. The controller 20 is configured to control the first solid state light source 3. The light generating system 1 further comprises an optional sensor 21. The sensor 21 is configured to sense an operational parameter of the light generating system 1 and to provide the sensed operational parameter to the controller 20. The controller 20 may then further be configured to receive the sensed operational parameter from the sensor 21 and use the received sensed operational parameter for controlling the first solid state light source 3.

[0162] The light generating system 1 further comprises at least one optional beamdump 15, cf. Fig. 6. The beam dump 15 is arranged and configured to absorb first collimated light source light 6. The beam dump 15 may thereby absorb first collimated light source light2025PF80029

[0163] 17

[0164] 6, which in case the first light redirecting optical element 8 is removed would escape the light generating system 1. The beam dump 15 may be ring shaped.

[0165] The light generating system 1 may further comprise an optional optical element 13 arranged downstream of the collimator 12. The optical element 13 is a transparent optical element for the first reflected light 6’ and the first converted light 10.

[0166] Fig. 2 shows a schematical side view of another light generating system 100 according to the invention and seen from the first angle of view. Fig. 3 shows the light generating system 100 seen from a second angle of view perpendicular to the first angle of view. The light generating system 100 differs from the light generating system 1 described above and shown in Fig. 1 in virtue of the following features.

[0167] The light generating system 100 further comprises a second solid state light source 33. The second solid state light source 33 is configured to, in operation, emit third light source light 34. The third light source light 34 comprises a fourth peak emission wavelength, X4, being in a wavelength range from 430 nm to 490 nm. The second solid state light source 33 comprises one or more of a laser diode, a super-luminescent diode, and a stacked multi -junction light-emitting diode. It is feasible that more than one second solid state light source 33 may be provided. The second solid state light source 33 may further be configured to emit further second light source light having a further peak emission wavelength, , being in a wavelength range of 600 nm to 680 nm. The second solid state light source 33 may be a canned second solid state light source.

[0168] A second collimating optical element 35 is arranged downstream of the second solid state light source 33. The second collimating optical element 35 is configured to collimate the third light source light 34 into a beam of second collimated light source light 36.

[0169] The first light redirecting optical element 8 is further configured to, at a surface of the plurality of specularly reflecting surfaces 82-85, receive the beam of second collimated light source light 36, and redirect the beam of second collimated light source light 36 onto the first major surface 71 of the luminescent element 7 such that a second main optical axis A2 of the beam of second collimated light source light 36 propagating from the first light redirecting optical element 8 towards the luminescent element 7 form a second angle a2 with respect to a normal B to the first major surface 71 of the luminescent element 7 - cf. Fig. 4. The second angle a2 may fulfill 3 degrees < a2 < 15 degrees. The beam of first collimated light source light 6 and the beam of second collimated light source light 36 propagate towards the luminescent element 7 from mutually different directions.2025PF80029

[0170] 18

[0171] Referring to Fig. 6, the beam of second collimated light source light 36 is reflected by a second specularly reflecting surface 83 of the plurality of specularly reflecting surfaces 82-85 such that an angle P2 is formed between the second main optical axis A2 and the second specularly reflecting surface 83 of the plurality of specularly reflecting surfaces 82-85. The angle P2 fulfills 48 degrees < P2 < 60 degrees. The first specularly reflecting surface 82 reflecting the beam of first collimated light source light 6 is different from the second specularly reflecting surface 83.

[0172] Referring to Fig. 7, the beam of second collimated light source light 36 is directed to the second specularly reflecting surface 83 of the plurality of specularly reflecting surfaces 82-85 with a fourth main optical axis D2 extending in an angle 52 with the axis E extending perpendicular to the normal B to the first major surface 71 of the luminescent element 7. The angle 52 fulfills 0 degrees < 52 < 20 degrees, or 0 degrees < 52 < 15 degrees, or 0 degrees < 52 < 10 degrees.

[0173] It is noted that in principle only one of the above-described conditions relating to the angle y and the angle 52, respectively, need to be fulfilled.

[0174] The luminescent element 7 is further configured to convert a part of the second collimated light source light 36 into second converted light 38. The second converted light 38 comprises a fifth peak emission wavelength, 5, being in a wavelength range of 500 nm to 590 nm. The luminescent element 7 is further configured to reflect a part of the second collimated light source light 36 as second reflected light 36’. A major part of the second converted light 38 and a major part of the second reflected light 36’, such as at least 60 %, at least 80 % or at least 90 % of the second converted light 38 and the second reflected light 36’, respectively, does not impinge onto the first light redirecting optical element 8.

[0175] The system light 2 thus further comprises, in an operational mode, the second reflected light 36’ and the second converted light 38. The first collimator 12 is further configured to collimate the second reflected light 36’ and the second converted light 38.

[0176] The first collimated light source light 6 forms a first spot on the first major surface 71 of the luminescent element 7. The second collimated light source light 36 forms a second spot on the first major surface 71 of the luminescent element 7. The first spot and the second spot form an overlap being at least 70 % defined by FWHM.

[0177] Referring now specifically to Fig. 3, the light generating system 100 further comprises an optional third solid state light source 43. The third solid state light source 43 is configured to, in operation, emit fourth light source light 44. The fourth light source light 44 comprises a sixth peak emission wavelength, Z6, being in a wavelength range from 430 nm to2025PF80029

[0178] 19

[0179] 490 nm. The third solid state light source 44 comprises one or more of a laser diode, a super-luminescent diode, and a stacked multi -junction light-emitting diode. It is feasible that more than one third solid state light source 43 may be provided. The third solid state light source 43 may further be configured to emit further fourth light source light having a further peak emission wavelength, , being in a wavelength range of 600 nm to 680 nm. The third solid state light source 43 may be a canned third solid state light source.

[0180] An optional third collimating optical element 45 is arranged downstream of the at least one third solid state light source 43. The third collimating optical element 45 is configured to collimate the fourth light source light 44 into a beam of third collimated light source light 46.

[0181] The first light redirecting optical element 8 is further configured to, at a surface of the plurality of specularly reflecting surfaces 82-85, receive the beam of third collimated light source light 46. The first light redirecting optical element 8 is further configured to redirect the beam of third collimated light source light 46 onto the first major surface 71 of the luminescent element 7 such that a third main optical axis A3 of the beam of third collimated light source light 46 propagating from the first light redirecting optical element 8 towards the luminescent element 7 form a third angle a3 with respect to a normal B to the first major surface 71 of the luminescent element - cf. Fig. 5. The third angle a3 fulfills 3 degrees < a3 < 15 degrees.

[0182] The beam of third collimated light source light 46 is reflected by a third specularly reflecting surface 84 of the plurality of specularly reflecting surfaces 82-85 such that an angle P3 is formed between a main optical axis of the beam of third collimated light source light 46 and the third specularly reflecting surface 84 of the plurality of specularly reflecting surfaces 82-85. The angle P3 fulfills 48 degrees < P3 < 60 degrees. The angle, P3, may alternatively fulfil 50 degrees < P3 < 58 degrees, 51 degrees < P3 < 57 degrees, or 52 degrees < P3 < 56 degrees. The first specularly reflecting surface 82 and the second specularly reflective surface 83 are different from the third specularly reflecting surface 84.

[0183] The beam of third collimated light source light 46 is directed to the third specularly reflecting surface 84 of the plurality of specularly reflecting surfaces 82-85 with a main optical axis of the beam of third collimated light source light 46 extending in an angle 53 with the axis E extending perpendicular to the normal B to the first major surface 71 of the luminescent element 7. The angle 53 fulfills 0 degrees < 53 < 20 degrees, or 0 degrees < 53 < 15 degrees, or 0 degrees < 53 < 10 degrees.2025PF80029

[0184] 20

[0185] The beam of first collimated light source light 6, the beam of second collimated light source light 36, and the beam of third collimated light source light 46 propagate towards the luminescent element 7 from mutually different directions.

[0186] The luminescent element 7 is further configured to convert a part of the beam of third collimated light source light 46 into third converted light 48. The third converted light 48 comprises a seventh peak emission wavelength, 7, being in a wavelength range of 500 nm to 590 nm. The luminescent element 7 is further configured to reflect part of the third collimated light source light 46 as third reflected light 46’. A major part of the third converted light 48 and a major part of the third reflected light 46’, such as at least 60 %, at least 80 % or at least 90 % of the third converted light 48 and the third reflected light 46’, respectively, does not impinge onto the first light redirecting optical element 8.

[0187] The luminescent element 7 may further optionally be configured to reflect and diffuse a part of the first collimated light source light 6, a part of the second collimated light source light 36, and, where a third solid state light source is provided, a part of the third collimated light source light 46. Thereby, first reflected and diffused light 6’, second reflected and diffused light 36’, and third reflected and diffused light 46’ may be provided.

[0188] The system light 2 thus further comprises, in an operational mode, the third reflected light 46’ and the third converted light 48. The first collimator 12 is further configured to collimate the third reflected light 46’ and the third converted light 48.

[0189] The luminescent element 7 may be arranged on a substrate 11, cf. Figs. 4-7. The substrate 11 may be a heat sink configured to lead heat away from the luminescent element 7. Also, a housing 22 (cf. Fig. 2) of the luminescent element 100 may be configured to form a heat sink such as to further improve the cooling of the luminescent element 7 and / or such as to lead away heat from and thus cool the first solid state light source 3, the second solid state light source 33 and, where provided, the third solid state light source 43.

[0190] The at least one second solid state light source 33 may, as illustrated in Fig. 2, be arranged behind and to a second side 17 of the luminescent element 7. The second solid state light source 33 and the first light redirecting element 8 may be arranged at mutually opposite sides of the luminescent element 7. The second solid state light source 33 may be arranged offset to the second side 17 of the luminescent element 7.

[0191] An optional second reflecting element 39 is arranged downstream of the second collimating element 35. The second reflecting element 39 is configured to direct the beam of second collimated light source light 36 to the first light redirecting optical element 8.2025PF80029

[0192] 21

[0193] Likewise, and as illustrated in Fig. 3, the at least one third solid state light source 43 may be arranged behind and to a third side 18 of the luminescent element 7. The third solid state light source 43 and the first light redirecting element 8 may be arranged at mutually opposite sides of the luminescent element 7. The third solid state light source 43 may be arranged offset to the third side 18 of the luminescent element 7. The first side 16, the second side 17 and the third side 18 are mutually different sides.

[0194] An optional third reflecting element 49 is arranged downstream of the third collimating element 45. The third reflecting element 49 is configured to direct the third collimated light source light 46 to the first light redirecting optical element 8.

[0195] The light generating system 100 further comprises an optional controller 20. The controller 20 is configured to individually control the first solid state light source 3, the second solid state light source 33, and the third solid state light source 43. The light generating system 100 further comprises an optional sensor 21. The sensor 21 is configured to sense an operational parameter of the light generating system 1, and to provide the sensed operational parameter to the controller 20. The controller 20 may then further be configured to receive the sensed operational parameter from the sensor 21 and use the received sensed operational parameter for controlling the first solid state light source 3, the second solid state light source 33, and the third solid state light source 43.

[0196] The light generating system 100 further comprises two or three optional beamdumps 15, cf. Fig. 6. The beam dumps 15 are arranged and configured to absorb first collimated light source light 6, second collimated light source light 36, and, where a third solid state light source 43 is provided, third collimated light source light 46, respectively. Thereby, the beam dumps 15 may absorb first collimated light source light 6, second collimated light source light 36, and, where a third solid state light source 43 is provided, third collimated light source light 46, respectively, which in case the first light redirecting optical element 8 is removed would escape the light generating system 100. At least one of the beam dumps 15 may be ring shaped.

[0197] The light generating system 100 may further comprise an optional optical element 13 arranged downstream of the collimator 12. The optical element 13 is a transparent optical element for the first reflected light 6’ and the first converted light 10, for the second reflected light 36’ and the second converted light 38, and, where a third solid state light source 43 is provided, for the third reflected light 46’ and the third converted light 48.

[0198] Put in more general terms, the light generating system 1, 100 may comprise N solid state light sources 3, 33, 43, and the plurality of specularly reflecting surfaces 82-85 of2025PF80029

[0199] 22

[0200] the first light redirecting element 8 may comprise M specularly reflecting surfaces. As described above N is 1, 2 or 3, while M may be 1, 2, 3 or above 3. It is also feasible that M and N may be chosen to fulfill M > 4 and N > 4, or M > 5 and N > 5, or M > 6 and N > 6.

[0201] Referring now to Fig. 8, a perspective view of an exemplary first light redirecting element 8 is shown. The first light redirecting optical element 8 comprises a base 81 and a plurality of specularly reflecting surfaces 82-85. The plurality of specularly reflecting surfaces 82-85 extend from the base 81. The base 81 comprises a length L and a width W. The length L may be chosen to be smaller than or equal to 7 mm. The width W may be chosen to be smaller than or equal. Alternatively, or additionally, the first collimator 12 comprises a diameter H, cf. Fig. 7. Each of the length L and the width W of the base 81 may be chosen to be less than or equal to 1 / 10 of the diameter H of the collimator 12.

[0202] The first light redirecting optical element 8 is mounted on an optional transparent substrate 14. The first light redirecting optical element 8 may be V-shaped or, as shown in Fig. 8, pyramid-shaped.

[0203] Referring now to Figs. 9 and 10, simulations on a light generating system 1, 100 according to the invention are shown.

[0204] Fig. 9 illustrates the reflectance from the first major surface 71 of an exemplary luminescent element 7 comprising a luminescent material being a Yttrium Aluminum Garnet (YAG) phosphor as a function of the angle of incidence for light of two different polarizations, namely p polarization and s polarization, as well as for an average of the two polarization directions. It may be seen that for angles up to 20 degrees p polarized light and s polarized light are reflected to the same extent. For angles above 20 degrees the magnitude of the average reflection increases. It may further be seen that the surface reflection becomes dependent on the polarization direction and also the direction of the angle of the incident light beam. For example, if the first light redirecting optical element 8, which directs the light towards the luminescent element 7, has a conical shape, reflected (blue) light from the luminescent element 7 will not be symmetric. Therefore, the incident angular range of up to 20 degrees has shown to be optimal for keeping the surface reflection to a minimum and also independent of the polarization direction.

[0205] Fig. 10 shows a graph illustrating the intensity of (i) the light reflected from the luminescent element 7 when the light is incident at an angle of 10 degrees (dashed line) and 20 degrees (solid line), respectively, to the first major surface 71 of an exemplary luminescent element 7 comprising a luminescent material being a Yttrium Aluminum Garnet (YAG) phosphor, and (ii) the phosphor light emitted from the same luminescent element 72025PF80029

[0206] 23

[0207] (dot-dashed line), as a function of the angle of incidence. As may be seen the intensity of the reflected light shows a Lambertian intensity distribution. This also includes (blue) light reflected from the bulk of the luminescent element 7. It may also be seen that when the reflected (blue) which was incident to the surface at angles of 10 and 20 degrees, respectively, is added to the Lambertian emission, this light remains in the interval of -20 degrees to 20 degrees. Light from small angles is necessary for obtaining highly collimated white light.

[0208] Referring now to Fig. 11, different suitable phosphors for a light generating system 1, 100 according to the invention will be described.

[0209] Garnet class

[0210] Generally, garnet class phosphors are suitable for use as a luminescent material for the luminescent element 7. Garnet class phosphors are luminescent materials of the type AsBsO 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.

[0211] 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 is2025PF80029

[0212] 24

[0213] 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.

[0214] Fig. 11 shows a graph of the intensity in arbitrary units as a function of the wavelength of emission (Em; solid line) and excitation (Ex; dashed line), respectively, for another suitable garnet class phosphor, namely a Yttrium Aluminum Garnet (YAG) phosphor. YAG phosphors are efficient and suitable for creating a high correlated color temperature (CCT). YAG phosphors exhibit absorption peaks at 450 nm, and dominant emission wavelengths range from 540 nm - 560 nm. YAG phosphors can be effectively excited by a 450 nm blue LED chip with an emission peak wavelength in the 540 nm - 560 nm range. YAG phosphors are mainly used for increasing luminous efficiency. By adding a small amount of a YAG yellow phosphor to an Ra80 LED, the luminous flux will increase dramatically. YAG phosphors are particularly suitable for use as a luminescent material for the luminescent element 7.

[0215] Another suitable garnet class phosphor is a Lutetium Aluminum Garnet (LuAG) phosphor. LuAG phosphors offer performance comparable to YAG phosphors. LuAG phosphors may have dominant emission wavelengths ranging from 520 nm to 540 nm. LuAG phosphors are generally used in conjunction with red phosphors for high CRI full spectrum coverage. LuAG phosphors can be effectively excited by a 450 nm blue LED with an emission peak wavelength in the 510-540 nm range. Combined with nitride red phosphor, a high CRI spectrum with Ra above 95 can be achieved. LuAG phosphors are particularly suitable for use as a luminescent material for the luminescent element 7.

[0216] Fig. 12 shows an exemplary lamp 300 comprising a light generating system 1, 100 according to any embodiment of the invention. In the embodiment shown, the light generating system 1, 100 comprises a substantially straight light generating system. The light generating system of such a lamp may in other embodiments be a light generating system with another shape, such as, but not limited to, spiral-shaped, helix-shaped, meandering, twisted, flat and combinations thereof.

[0217] The lamp 300 further comprises a driver or controller 305 configured for controlling the solid state light sources 3, 33, 43 of the light generating system 1, 100. The controller 305 is configured to power the solid state light sources 3, 33, 43 via electrical circuitry (not visible on the figures) of the light generating system 1, 100. The light2025PF80029

[0218] 25

[0219] generating system 1, 100 may also comprise a controller 20, which may or may not be separate from the controller 305. In other words, the controller 305 and the controller 20 of the light generating system 1, 100 may be integrated into one and the same driver or controller, or they may be mutually separate units.

[0220] The lamp 300 further comprises an envelope 301 at least partially enveloping the at least one light generating system 1, 100. The lamp 300 further comprises a cap 303. As shown in Fig. 12, the controller 305 is arranged within the envelope 301. When comprising a cap 303, the controller 305 may also be arranged inside the cap 303 such that it is hidden from view. The lamp 300 further comprises threading 302 for connection to a socket, and a terminal 304 for connection to a source of electrical energy.

[0221] The envelope 301 of the lamp 300 may further and optionally be provided with a coating (not shown), such as a reflective coating, covering at least a part of the envelope 301.

[0222] Turning finally to Fig. 13, an exemplary luminaire in the form of a projector 400 is shown. The projector 400 comprises a light generating system 1, 100 according to any embodiment of the invention. The light generating system 1, 100 is as shown in Fig. 13 provided within a lamp 300 in the form of a light bulb.

[0223] As is also mentioned above, the light bulb further comprises a transparent envelope (cf. transparent envelope 301 of lamp 300) at least partially enveloping the at least one light generating system 1, 100. The transparent envelope may be shaped in any feasible shape, for example such as to resemble the shape of any one of a standard light bulb, a globe light bulb, a candlelight bulb, a customized light bulb and even a spiral light bulb. The transparent envelope may comprise a luminescent material. The transparent envelope may be a glass envelope.

[0224] The projector 400 further comprises a socket 401 for connecting the lamp 300, and thereby the light generating system 1, 100, to the projector 400. The socket 401 is adapted to cooperate with the base 303 of the lamp 300. The socket 401 may comprise a threading adapted to cooperate with the threading 302 of the lamp 300. The socket 401 may comprise a terminal adapted to cooperate with the terminal 304 of the lamp 300. The projector 400 further comprises a reflector or screen 403.

[0225] The projector 400 may further comprise a driver 402 configured for controlling the light generating system 1, 100. The driver 402 may or may not be the same unit as the controller 305 described above. In other words, the driver 402 and the controller 305 may be integrated into one and the same driver or controller, or they may be mutually2025PF80029

[0226] 26

[0227] separate units. Alternatively, or additionally, the light generating system 1, 100 may also comprise a controller 20, which may or may not be separate from one or both of the driver 402 and the controller 305.

[0228] As shown in Fig. 13, the driver 402 is arranged on a reflector or screen 403 of the projector 400. The driver may also be arranged within or incorporated into the reflector or screen 403. The projector 400 further comprises an electrical wiring 404 for connection to a source of electricity, such as a mains.

[0229] It is noted that the projector 400 shown in Fig. 13 is only one example of a luminaire according to the invention. Any suitable type of luminaire may be envisaged, such as but not limited to, vehicle lights, search lights, stage lighting devices, luminaires for display applications, such as LED displays, LCD displays and OLED displays, a standing luminaire, a wall hung luminaire, a chandelier, a reading luminaire, an outdoor luminaire, and a table luminaire.

[0230] The person skilled in the art realizes that the present invention by no means is limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims.

[0231] Additionally, variations to the disclosed embodiments can be understood and effected by the skilled person in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage.

Claims

2025PF8002927CLAIMS:

1. A light generating system (1) configured to, in operation, emit system light (2), the light generating system comprising:at least one first solid state light source (3) configured to, in operation, emit first light source light (4) having a first peak emission wavelength, I, being in a wavelength range of 430 nm to 490 nm, the at least one first solid state light source comprising one or more of a laser diode, a super-luminescent diode, and a stacked multi -junction light-emitting diode,a first collimating optical element (5) arranged downstream of the at least one first solid state light source (3) and configured to collimate the first light source light (4) into a beam of first collimated light source light (6),a luminescent element (7) being arranged downstream of the first solid state light source, the luminescent element comprising a first major surface (71) and a second major surface (72) opposite to the first major surface, anda first light redirecting optical element (8) being arranged in front of and centered with respect to the luminescent element; whereinthe first light redirecting optical element (8) is a specular reflector comprising a plurality of specularly reflecting surfaces (82-85) configured to (i) receive the beam of the first collimated light source light (6), and (ii) redirect the beam of the first collimated light source light (6) onto the first major surface (71) of the luminescent element (7) such that a first main optical axis (Al) of the beam of the first collimated light source light (6) propagating from the first light redirecting optical element (8) towards the luminescent element (7) forms a first angle (al) with respect to a normal (B) to the first major surface (71) of the luminescent element, wherein the first angle (al) fulfills 3 degrees < al < 15 degrees; whereinthe luminescent element (7) is configured to convert a part of the first collimated light source light (6) into first converted light (10) having a second peak emission wavelength, X2, being in a wavelength range of 500 nm to 590 nm, and wherein the luminescent element further is configured to reflect part of the collimated light source light (6) as first reflected light (6’); wherein2025PF8002928the light generating system further comprises a first collimator (12) arranged downstream of the luminescent element (7) and configured to collimate the first reflected light (6’) and the first converted light (10); and whereinthe system light (2) comprises, in an operational mode, a combination of the first reflected light (6’) and the first converted light (10), and the system light is white light having a correlated color temperature in a range from 2000 K to 9000 K and a color rendering index of at least 65.

2. A light generating system according to claim 1, wherein the at least one first solid state light source (3) further is configured to emit second light source light (4’) having a third peak emission wavelength, 3, being in a wavelength range of 600 nm to 680 nm.

3. A light generating system according to any one of the above claims, further comprising at least one second solid state light source (33) configured to, in operation, emit third light source light (34) having a fourth peak emission wavelength, X4, being in a wavelength range from 430 nm to 490 nm, the at least one second solid state light source comprising one or more of a laser diode, a super-luminescent diode, and a stacked multijunction light-emitting diode, anda second collimating optical element (35) arranged downstream of the at least one second solid state light source (33) and configured to collimate the third light source light (34) into a beam of second collimated light source light (36); whereinthe plurality of specularly reflecting surfaces (82-85) of the first light redirecting optical element (8) further is configured to (iii) receive the beam of second collimated light source light (36), and (iv) redirect the beam of second collimated light source light (36) onto the first major surface (71) of the luminescent element (7) such that a second main optical axis (A2) of the beam of second collimated light source light (36) propagating from the first light redirecting optical element (8) towards the luminescent element (7) form a second angle (a2) with respect to a normal (B) to the first major surface (71) of the luminescent element, wherein the second angle (a2) fulfills 3 degrees < a2 < 15 degrees; whereinthe beam of first collimated light source light (6) and the beam of second collimated light source light (36) propagate towards the luminescent element (7) from mutually different directions; wherein2025PF8002929the luminescent element (7) further is configured to convert a part of the second collimated light source light (36) into second converted light (38) having a fifth peak emission wavelength, 5, being in a wavelength range of 500 nm to 590 nm, and wherein the luminescent element further is configured to reflect part of the second collimated light source light (36) as second reflected light (36’); whereinthe first collimator (12) is further configured to collimate the second reflected light (36’) and the second converted light (38); and whereinthe system light (2) further comprises, in an operational mode, the second reflected light (36’) and the second converted light (38).

4. A light generating system according to claim 3, wherein the first collimated light source light (6) forms a first spot on the first major surface (71) of the luminescent element (7), wherein the second collimated light source light (36) forms a second spot on the first major surface (71) of the luminescent element (7), and wherein the first spot and the second spot form an overlap being at least 70 % defined by full width of half maximum, FWHM.

5. A light generating system according to any one of the above claims, wherein the beam of first collimated light source light (6) is reflected by a first specularly reflecting surface of the plurality of specularly reflecting surfaces (82-85) such that an angle (P 1) between the first main optical axis (Al) and the first specularly reflecting surface of the plurality of specularly reflecting surfaces (82-85) fulfills 48 degrees < pi < 60 degrees; wherein,when the second solid state light source (33) is provided, the beam of second collimated light source light (36) is reflected by a second specularly reflecting surface of the plurality of specularly reflecting surfaces (82-85) such that an angle (P2) between the second main optical axis (A2) and the second specularly reflecting surface of the plurality of specularly reflecting surfaces (82-85) fulfills 48 degrees < P2 < 60 degrees; and wherein the first specularly reflecting surface being different from the second specularly reflecting surface.

6. A light generating system according to any one of the above claims, wherein the first light redirecting optical element (8) further comprises a base (81) from which the plurality of specularly reflecting surfaces (82-85) extend, and wherein the plurality of2025PF8002930specularly reflecting surfaces (82-85) form an angle (y) with respect to the base (81), wherein the angle (y) fulfills 60 degrees < y < 66 degrees.

7. A light generating system according to any one of the above claims, wherein the beam of first collimated light source light (6) is directed to a first specularly reflecting surface of the plurality of specularly reflecting surfaces (82-85) with a third main optical axis (DI) extending in an angle (51) with an axis (E), the axis (E) extending perpendicular to the normal (B) to the first major surface (71) of the luminescent element, wherein the angle (51) fulfills 0 degrees < 51 < 20 degrees, or 0 degrees < 51 < 15 degrees, or 0 degrees < 51 < 10 degrees, and wherein,when the second solid state light source (33) is provided, the beam of second collimated light source light (36) is directed to a second specularly reflecting surface of the plurality of specularly reflecting surfaces (82-85) with a fourth main optical axis (D2) extending in an angle (52) with the axis (E), the axis (E) extending perpendicular to the normal (B) to the first major surface (71) of the luminescent element, wherein the angle (52) fulfills 0 degrees < 52 < 20 degrees, or 0 degrees < 52 < 15 degrees, or 0 degrees < 52 < 10 degrees.

8. A light generating system according to any one of the above claims, further comprising at least one third solid state light source (43) configured to, in operation, emit fourth light source light (44) having a sixth peak emission wavelength, <6, being in a wavelength range from 430 nm to 490 nm, the at least one third solid state light source comprising one or more of a laser diode, a super-luminescent diode, and a stacked multijunction light-emitting diode, anda third collimating optical element (45) arranged downstream of the at least one third solid state light source (43) and configured to collimate the fourth light source light (44) into a beam of third collimated light source light (46); whereinthe plurality of specularly reflecting surfaces (82-85) of the first light redirecting optical element (8) further is configured to (v) receive the beam of third collimated light source light (46), and (vi) redirect the beam of third collimated light source light (46) onto the first major surface (71) of the luminescent element (7) such that a fifth main optical axis (A3) of the beam of third collimated light source light (46) propagating from the first light redirecting optical element (8) towards the luminescent element (7) form a2025PF8002931third angle (a3) with respect to a normal (B) to the first major surface (71) of the luminescent element, wherein the third angle (a3) fulfills 3 degrees < a3 < 15 degrees; whereinthe beam of first collimated light source light (6), the beam of second collimated light source light (36), and the beam of third collimated light source light (46) propagate towards the luminescent element (7) from mutually different directions; wherein the luminescent element (7) further is configured to convert a part of the beam of third collimated light source light (46) into third converted light (48) having a seventh peak emission wavelength, 7, being in a wavelength range of 500 nm to 590 nm, and wherein the luminescent element further is configured to reflect part of the third collimated light source light (46) as third reflected light (46’); whereinthe first collimator (12) further is configured to collimate the third reflected light (46’) and the third converted light (48); and whereinthe system light (2) further comprises, in an operational mode, the third reflected light (46’) and the third converted light (48).

9. A light generating system according to any one of the above claims, wherein the light generating system (1) comprises N solid state light sources (3, 33, 43), wherein the plurality of specularly reflecting surfaces (82-85) comprises M specularly reflecting surfaces, and wherein M > 4 and N > 4, or M > 5 and N > 5, or M > 6 and N > 6.

10. A light generating system according to any one of the above claims, wherein the first light redirecting optical element (8) comprises a base (81) from which the plurality of specularly reflecting surfaces (82-85) extend, the base (81) comprising a length (L) and a width (W), whereineach of the length (L) and the width (W) is < 7 mm, and wherein each of the length (L) and the width (W) is less than or equal to 1 / 10 of a diameter (H) of the collimator (12).

11. A light generating system according to any one of the above claims, wherein one or more of the following applies:the at least one first solid state light source (3) is arranged at a side of the luminescent element (7) opposite to the first light redirecting optical element (8) and offset to a first side (16) of the luminescent element (7),2025PF8002932where provided, the at least one second solid state light source (33) is arranged at a side of the luminescent element (7) opposite to the first light redirecting optical element (8) and offset to a second side (17) of the luminescent element,where provided, the at least one third solid state light source (43) is arranged at a side of the luminescent element (7) opposite to the first light redirecting optical element (8) and offset to a third side (18) of the luminescent element,a first reflecting element (9) is arranged downstream of the first collimating element (5) and configured to direct the first collimated light source light (6) to the first light redirecting optical element (8),where a second light source (33) is provided, a second reflecting element (39) is arranged downstream of the second collimating element (35) and configured to direct the second collimated light source light (36) to the first light redirecting optical element (8), and where a third light source (43) is provided, a third reflecting element (49) is arranged downstream of the third collimating element (45) and configured to direct the third collimated light source light (46) to the first light redirecting optical element (8).

12. A light generating system according to any one of the above claims, wherein the following applies:the first light redirecting optical element (8) is V-shaped or pyramid-shaped, anda major part of the first converted light (10) and a major part of the first reflected light (6’) does not impinge onto the first light redirecting optical element (8), where at least one second solid state light source (33) is provided, a major part of the second converted light (38) and a major part of the second reflected light (36’) does not impinge onto the first light redirecting optical element (8), and where at least one third solid state light source (43) is provided, a major part of the third converted light (48) and a major part of the third reflected light (46’) does not impinge onto the first light redirecting optical element (8).

13. A light generating system according to any one of the above claims, and further comprising a controller (20) configured to individually control the at least one first solid state light source (3), where provided, the at least one second solid state light source (33), and, where provided, the at least one third solid state light source (43), and optionally a sensor (21) configured to sense an operational parameter of the light generating system (1) and to provide the sensed operational parameter to the controller (20) for controlling the first2025PF8002933solid state light source (3), where provided, the at least one second solid state light source (33), and, where provided, the at least one third solid state light source (43).

14. A light generating system according to any one of the above claims, and further comprising at least one beam-dump (15) arranged and configured to absorb first collimated light source light (6), where a second solid state light source (33) is provided, second collimated light source light (36), and, where a third solid state light source (43) is provided, third collimated light source light (46), which in case the first light redirecting optical element (8) is removed would escape the light generating system (1).

15. A lamp or a luminaire, a vehicle light, projection device, a search light, or a stage lighting device comprising a light generating system (1) according to any one of the above claims.

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