High efficiency polarized light

Abstract

A light generating system for producing system light. Initial laser light having a peak wavelength in a first wavelength range is produced by a laser light source. The initial laser light is received by a first phosphor arrangement configured to at least partially convert this light into first converted light in having a peak wavelength in a different wavelength range. Light from the phosphor arrangement comprising the first converted light is received at a reflective polarizer. The reflective polarizer is configured to split the (first converted) light according to its polarization. First converted light of a first linear polarization is transmitted by the reflective polarizer, whereas first converted light of second linear polarization orthogonal to the first linear polarization is reflected. The reflected (first converted) light of the second linear polarization is subsequently passed twice through an achromatic quarter waveplate to convert this light to the first linear polarization, thereby allowing said light to be transmitted through the reflective polarizer. The light transmitted by the reflective polarizer is combined into an output light beam of the first linear polarization.

Description

[0001] 2024PF80293

[0002] 1

[0003] HIGH EFFICIENCY POLARIZED LIGHT

[0004] FIELD OF THE INVENTION

[0005] The present invention relates to the field of optics, and in particular to systems for producing polarized light.

[0006] BACKGROUND OF THE INVENTION

[0007] Polarized light can be used in various applications such as in stage-lighting, projection-TV, automotive headlights, and in several areas of scientific research. Light can be polarized along a particular direction by passing unpolarized light (or light otherwise polarized along an undesired direction) through a polarizing filter. However, this typically results in a large proportion of the initial light being absorbed by the polarizing filter, e.g., light polarized perpendicular to the polarization direction of the filter. There is thus a desire for methods and systems capable of producing polarized light with higher efficiency.

[0008] SUMMARY OF THE INVENTION

[0009] The invention is defined by the claims.

[0010] According to proposed examples, there is provided a light generating system configured in operation, system light, the light generating system comprising: a first laser light source configured to provide, in operation, first laser light having a first peak emission wavelength, X, in a first wavelength range of from 400 nm to 490 nm; and a first optical arrangement configured to receive the first laser light and output first arrangement light which forms at least part of the system light.

[0011] The first optical arrangement comprises a first phosphor arrangement, a first reflective polarizer, and an achromatic quarter waveplate.

[0012] The first phosphor arrangement comprises a first polarization maintaining phosphor layer configured to receive the first laser light at a first side of the first polarization maintaining phosphor layer, wherein at least part of the received first laser light is converted by the first polarization maintaining phosphor layer into first converted light having a second peak emission wavelength, 2, in a second wavelength range of from 500 nm to 670 nm; and a first specularly reflective metallic mirror arranged at a second side of the first polarization2024PF80293

[0013] 2

[0014] maintaining phosphor layer, opposite the first side, the first specularly reflective metallic mirror being configured to reflect at least part of the first converted light.

[0015] The first reflective polarizer is configured to receive at least part of the first converted light from the first phosphor arrangement, wherein the first reflective polarizer is configured to: transmit first converted light having a first linear polarization direction; and reflect first converted light having a second linear polarization direction which is orthogonal to the first linear polarization direction, wherein the reflected first converted light, having the second linear polarization direction, is directed towards the first phosphor arrangement.

[0016] The achromatic quarter waveplate is arranged between the first phosphor arrangement and the first reflective polarizer, wherein: the first converted light having the second linear polarization direction and reflected by the first reflective polarizer passes through the achromatic quarter waveplate and is subsequently reflected by the first phosphor arrangement and passes through the achromatic quarter waveplate whereby the first converted light having the second linear polarization direction is rotated to form further first converted light having the first linear polarization direction, wherein the further first converted light having the first linear polarization is transmitted through the first reflective polarizer, wherein the first arrangement light comprises the first converted light having the first linear polarization direction and the further first converted light having the first linear polarization direction.

[0017] The present disclosure provides a system for producing high efficiency linearly polarized light. The system comprises an optical arrangement for converting a laser light produced by a laser light source (e.g., a laser) from an initial polarized or unpolarized state to a target (i.e., first) linear polarization. Specifically, the optical arrangement comprises a pair of reflectors / mirrors (i.e., the specularly reflective metallic mirror and the first reflective polarizer) for directing the first laser light within the optical arrangement (i.e., between the two reflectors). The first reflective polarizer acts as a polarizing filter for transmitting light of the target linear polarization. The optical arrangement therefore effectively acts as an optical cavity for trapping light and only transmitting light of the target linear polarization.

[0018] The optical arrangement further comprises an achromatic quarter waveplate positioned between the two reflectors for modifying the polarization of the light. In particular, light reflected by the first reflective polarizer has a polarization direction which is perpendicular to the target polarization. After passing twice through the achromatic quarter waveplate (i.e., due to reflection by the specularly reflective metallic mirror) the polarization2024PF80293

[0019] 3

[0020] of said light is rotated by 90°, thereby changing the polarization direction of the light to the target polarization direction, thus allowing it to be transmitted by the reflective polarizer.

[0021] The proposed system may thus allow for the highly efficient conversion of the initial laser light into the target linear polarization, with light / energy primarily only being lost due to absorption effects. Particularly, use of the achromatic quarter waveplate allows for the polarization of light across a broad wavelength range, simplifying the system and further reducing light losses.

[0022] In some examples, the first optical arrangement may further comprise a first laser light reflector arranged between the first phosphor arrangement and the first reflective polarizer. Specifically, the first laser light reflector may be configured to receive the first laser light from the first laser light source and direct the first light beam towards the first phosphor arrangement.

[0023] For example, the first light beam reflector may comprise a dichroic beam splitter configured to configured to (i) reflect the first laser light and transmit the first converted light, or (ii) transmit the first laser light and reflect the first converted light.

[0024] In some examples, the first optical arrangement may further comprise a lens arranged between the first phosphor arrangement and the achromatic quarter waveplate, wherein: the first laser light from the first laser light source and light reflected by the first reflective polarizer pass through the lens before reaching the first phosphor arrangement, wherein the lens is configured to focus said light onto the first phosphor arrangement; and first converted light and further first converted light from the first phosphor arrangement passes through the lens before reaching the first reflective polarizer, wherein the lens is configured to collimate the first converted light and further first converted light from the first phosphor arrangement towards the first reflective polarizer.

[0025] Additionally, light from the first phosphor arrangement may pass through the lens before reaching the first reflective polarizer. Accordingly, the lens may be configured to collimate the light from the first phosphor arrangement towards the first reflective polarizer. In this way, light emitted and / or reflected by the first phosphor arrangement can be better directed towards the first reflective polarizer.

[0026] In some examples, the first polarization maintaining phosphor layer may comprise a transparent phosphor layer that exhibits a negligible degree of birefringence.

[0027] For example, the first polarization maintaining phosphor layer may comprise a phosphor of the type AsELO^Ce, where A comprises one or more of Y, La, Gd, Tb, and Lu,2024PF80293

[0028] 4

[0029] and B comprises one or more of Al, Ga, In, and Sc. In other words, the first polarization maintaining layer may comprise a garnet phosphor.

[0030] In some examples, the first polarization maintaining phosphor layer may comprise one or more refractive structures arranged at the first side and / or the second side of the first polarization maintaining phosphor layer. For example, the one or more refractive structures may be micro structures etched and / or patterned in / on to the surface(s) of the first polarization maintaining phosphor layer for controlling the transmission of incident light into the first polarization maintaining phosphor layer.

[0031] In some examples, the first specularly reflective metallic mirror may comprise: silver, aluminum, or any combination thereof. More generally, the specularly reflective metallic mirror may comprise any reflective metallic layer that induces a negligible (or at least not a substantial) change in polarization on reflected light. In other words, polarized light incident on the metallic layer maintains its state of polarization after being reflected.

[0032] In some examples, the achromatic quarter waveplate may comprise a combination of crystalline quartz and magnesium fluoride crystals, or a stack of oriented polymeric layers.

[0033] In some examples, the second peak emission wavelength lies in a wavelength range of from 550 nm to 650 nm.

[0034] Furthermore, the light generating system may additionally comprise either a second laser light source different to the first laser light source configured to provide, in operation, second laser light having a third peak emission wavelength in the first wavelength range; or a first intensity beam splitter configured to receive the first laser light and convert at least some of the first laser light into a second laser light having the first peak emission wavelength.

[0035] The light generating system may also comprise a second optical arrangement configured to receive the second laser light and output second arrangement light which forms at least part of the system light, wherein the polarization and / or the peak emission wavelength of the second arrangement light are different to the polarization and / or at the peak emission wavelength of the first arrangement light.

[0036] The light generating system may comprise one or more output reflectors configured to combine the second arrangement light with the first arrangement light.

[0037] According to the above system, the overall spectral (i.e., color) and polarization characteristics of the system light output by the light generating system can be controlled through tuning the first arrangement light and the second arrangement light. For2024PF80293

[0038] 5

[0039] example, when the first arrangement light and the second arrangement light comprise light of different linear polarizations, the two arrangement lights can be combined to produce a different linear polarization (and also increase the light output). As another example, when the first arrangement light and the second arrangement light comprise light of different colors, the two arrangement lights can be combined to produce an overall different color of light.

[0040] In some examples, the second optical arrangement may comprise a second phosphor arrangement different to the first phosphor arrangement. The second phosphor arrangement comprises: a second polarization maintaining phosphor layer configured to receive the second laser light at a first side of the second polarization maintaining phosphor layer, wherein at least part of the received second laser light is converted by the second polarization maintaining phosphor layer into second converted light having a fourth peak emission wavelength in the second wavelength range different to the second peak emission wavelength; and a second specularly reflective metallic mirror arranged at a second side of the second polarization maintaining phosphor layer, opposite the first side, configured to reflect at least part of the second converted light.

[0041] In this way, the wavelength range of the second arrangement light may be controlled and made different from that of the first arrangement light.

[0042] Additionally, or alternatively, the second optical arrangement may comprise a second reflective polarizer different to the first reflective polarizer, configured to receive at least part of the first converted light or second converted light from the first phosphor arrangement or a second phosphor arrangement, wherein the second reflective polarizer is configured to: transmit first converted light or second converted light having a third linear polarization different to the first linear polarization, wherein the light transmitted by the second reflective polarizer forms the second arrangement light; and reflect first converted light or second converted light having a fourth linear polarization orthogonal to the third linear polarization, wherein the received light reflected by the second reflective polarizer is reflected back towards the first phosphor arrangement or the second phosphor arrangement.

[0043] In some examples, each of the one or more output reflectors may comprise a dichroic beam splitter, a polarizing beam splitter, or any combination thereof.

[0044] Furthermore, the light generating system may comprise a third laser light source different to the first laser light source and the second laser light source configured to produce, in operation, a third laser light having a fifth peak emission wavelength in the first wavelength range; or a second intensity beam splitter configured to receive the first laser2024PF80293

[0045] 6

[0046] light or the second laser light and convert at least some of the first laser light or the second laser light into a third laser light having the first peak emission wavelength or the second peak emission wavelength.

[0047] The light generating system may comprise a third optical arrangement configured to receive the third laser light and output third arrangement light, wherein the polarization and / or the peak emission wavelength of the third arrangement light is different to the polarization and / or the peak emission wavelength of the first arrangement light and the peak emission wavelength of the second arrangement light; and one or more further output reflectors configured to combine the third arrangement light with the first arrangement light and the second arrangement light.

[0048] In accordance with the above examples, the polarized system light output by the light generating system may comprise linearly polarized white light.

[0049] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiment s) described hereinafter.

[0050] BRIEF DESCRIPTION OF THE DRAWINGS

[0051] For a better understanding of the invention, and to show more clearly how it may be carried into effect, reference will now be made, by way of example only, to the accompanying drawings, in which:

[0052] Fig. 1 schematically illustrates a light generating system;

[0053] Fig. 2 schematically illustrates paths of light rays within the light generating system;

[0054] Fig. 3 schematically illustrates an arrangement for the light generating system; Fig. 4 schematically illustrates another light generating system;

[0055] Fig. 5 schematically illustrates yet another light generating system; and Fig. 6 schematically illustrates yet another light generating system.

[0056] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0057] The invention will be described with reference to the Figures.

[0058] It should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the apparatus, systems and methods, are intended for purposes of illustration only and are not intended to limit the scope of the invention. These and other features, aspects, and advantages of the apparatus, systems and methods of the present invention will become better understood from the following2024PF80293

[0059] 7

[0060] description, appended claims, and accompanying drawings. It should be understood that the Figures are merely schematic and are not drawn to scale. It should also be understood that the same reference numerals are used throughout the Figures to indicate the same or similar parts.

[0061] There is herein proposed a light generating system for producing system light . Initial laser light having a peak wavelength in a first wavelength range is produced by a laser light source. The initial laser light is received by a first phosphor arrangement configured to at least partially convert this light into first converted light in having a peak wavelength in a different wavelength range. Light from the phosphor arrangement comprising the first converted light is received at a reflective polarizer. The reflective polarizer is configured to split the (first converted) light according to its polarization. First converted light of a first linear polarization is transmitted by the reflective polarizer, whereas first converted light of second linear polarization orthogonal to the first linear polarization is reflected. The reflected (first converted) light of the second linear polarization is subsequently passed twice through an achromatic quarter waveplate to convert this light to the first linear polarization, thereby allowing said light to be transmitted through the reflective polarizer. The light transmitted by the reflective polarizer is combined into an output light beam of the first linear polarization.

[0062] There is herein proposed a light generating system for outputting polarized light. The light generating system comprises a first laser light source i.e., a first laser) for producing first laser light (beam) having a first peak emission wavelength XI in a first wavelength range. The first wavelength range is from 400 nm to 490 nm. The first laser light is received by a first optical arrangement of the light generating system which is configured to convert (at least some of) the first laser light into first arrangement light.

[0063] More specifically, the first optical arrangement is configured to convert at least some of the first laser light into first converted light having a second peak emission wavelength in a second wavelength range different to the first wavelength range. The second wavelength range is from 500 nm to 670 nm. The first optical arrangement is also configured to control the polarization state of light within the first optical arrangement to only output light of a first linear polarization.

[0064] Figure 1 shows a schematic of a light generating system 100 comprising a first laser light source 105 and a first optical arrangement 110.

[0065] The first laser light source 105 is configured to produce (i.e., output) a first laser light having a first peak emission wavelength in a first wavelength range. In this context, laser light are substantially collimated (i.e., aligned along a particular direction) or at2024PF80293

[0066] 8

[0067] least subtends a limited angle of projection, e.g., less than 45°. In other words, light rays of laser light may share a substantially similar propagation direction.

[0068] Examples of suitable laser light sources for functioning as the first laser light source 105 would be well known to the skilled person, such as a gas laser, a solid-state laser, a laser diode, and so on. In this way, in practice, the first wavelength range may be substantially narrow and / or monochromatic. More generally, the first laser light source may comprise any light source capable of producing a laser beam of coherent light.

[0069] The first laser light has a first peak emission wavelength within the first wavelength range, which is in the range of from 400 nm to 490 nm, corresponding to wavelengths of light that are associated with blue light. In some examples, the first laser light may comprise light that is predominantly (e.g., more than 50% of the first laser light, more than 75% of the first laser light, or more than 90% of the first laser light) within the first wavelength range.

[0070] The first optical arrangement 110 comprises a series of optical elements which (in conjunction) are configured to manipulate the first laser light to produce / output first arrangement light of / in a first (i.e., target) linear polarization. In particular, as will be expanded on later, the first optical arrangement 110 is configured to receive the first laser light from the first laser light source 105 and manipulate the first laser light to produce the first arrangement light, i.e., convert (at least some of) the first laser light into the first arrangement light.

[0071] The first optical arrangement 110 comprises a first phosphor arrangement 120 configured to reflect light incident thereon and / or convert such incident light of the first peak emission wavelength into light having a second peak emission wavelength that lies in a different wavelength range to the first wavelength range, i.e., the second wavelength range.

[0072] More specifically, the first phosphor arrangement 120 comprises a first polarization maintaining phosphor layer 122 configured to receive the first laser light at a first side 121 of the first polarization maintaining phosphor layer 122. The first laser light received at (i.e., incident on) the first side 121 may pass into the first polarization maintaining phosphor layer 122. It is noted that some of the first laser light received at the first side 121 may propagate through the first polarization maintaining phosphor layer 122 to a second side 123 opposite the first side 121.

[0073] The first polarization maintaining phosphor layer is configured to convert at least part of the received first laser light into first converted light having a second peak2024PF80293

[0074] 9

[0075] emission wavelength, 2, in the second wavelength range. The second wavelength range is from 500 nm to 670 nm.

[0076] By way of explanation, while propagating through the first polarization maintaining phosphor layer 122, the first laser light has a finite chance of being converted (by the first polarization maintaining phosphor layer 122) into first converted light having the second peak emission wavelength (which is different to the first peak emission wavelength of the first laser light). More precisely, the received first laser light may be absorbed by the first polarization maintaining phosphor layer 122 and re-emitted as the first converted light.

[0077] To achieve this, the first polarization maintaining phosphor layer 122 may comprise one or more fluorescent materials each configured to absorb light of a respective predefined wavelength range (or more specifically light of a wavelength below a respective predefined wavelength threshold) and subsequently emit light in a further respective predefined wavelength range. In a typical phosphor layer, the further respective predefined wavelength range comprises wavelengths longer than that of the respective predefined wavelength range, i.e., the light emitted by the fluorescent material is of a lower energy than the light absorbed by the fluorescent material.

[0078] For the purposes of the present disclosure, if employed, the one or more fluorescent materials are each configured to absorb the first laser light having the first peak emission wavelength in the first wavelength band and subsequently emit the first converted light having the second peak emission wavelength in the second wavelength band.

[0079] The one or more fluorescent materials may be arranged in the first polarization maintaining phosphor layer 122 as small (e.g., micro or nano) particles suspended in a polarization maintaining (inert) medium, such as a polarization maintaining polymer (e.g., silicone) or a polarization maintaining crystal typically comprising an oxide, nitride, silicate, sulfide and / or selenide compound. A percentage change of light being absorbed by the first polarization maintaining phosphor layer 122 may thus be controlled from the concentration and / or size of fluorescent particles.

[0080] Additionally, the fluorescent particles may themselves be polarization maintaining or (at least) lightly scattering.

[0081] As will become clear later, the first polarization maintaining phosphor layer 122 may preferably comprise a transparent phosphor layer comprising a fluorescent material (or a combination of fluorescent materials) that does / do not exhibit birefringence or that at least exhibits a negligible degree of birefringence, i.e., the polarization state of light passing2024PF80293

[0082] 10

[0083] through the first polarization maintaining phosphor layer 122 is unchanged and / or negligibly affected.

[0084] Suitable examples of fluorescent materials may be a phosphor of the type AsBsOn Ce (i.e. a garnet phosphor), wherein A comprises one or more of Y, La, Gd, Tb and Lu, and wherein B comprises one or more of Al, Ga, In and Sc. These fluorescent materials exhibit the appropriate properties for converted light having the first peak emission wavelength to light having the second peak emission wavelength.

[0085] Other examples of suitable fluorescent materials will be apparent to the skilled person.

[0086] Additionally, the first polarization maintaining phosphor layer 122 may preferably comprise a surface structure that does not lead to multiple reflections, i.e., the first laser light incident on the first side 121 is either reflected by the first side 121 or transmitted into the bulk of the first polarization maintaining phosphor layer 122. For instance, the first polarization maintaining phosphor may comprise one or more refractive structures arranged at the first side 121 and / or the second side 123. The one or more refractive structures may, for example, be etched into or imprinted on the first polarization maintaining phosphor layer. Suitable refractive structures for controlling the reflection and transmission of light by the first polarization maintaining phosphor layer will be apparent to the skilled person.

[0087] According to the present example, the first polarization maintaining phosphor layer 122 is configured to absorb at least a portion (e.g., 50%, 75%, 100%, etc.) of first laser light propagating through the first polarization maintaining phosphor layer 122. Furthermore, following absorption of at least a portion of the first laser light, the first polarization maintaining phosphor layer 122 is configured to emit first converted light having the second peak emission wavelength (in a second wavelength range different to the first wavelength range). The first wavelength range and the second wavelength range do not overlap. In other words, at least a portion of the first laser light is absorbed and converted into first converted light by the first polarization maintaining phosphor layer 122.

[0088] The first phosphor arrangement 120 further comprises a first specularly reflective metallic mirror 124 arranged at / on (i.e., in contact with) the second side 123 of the first polarization maintaining phosphor layer 122. The first specularly reflective metallic mirror 124 is configured to reflect light, particularly (part of) the first converted light and (if relevant the first laser light incident on its surface. In particular, the first specularly reflective metallic mirror 124 is configured to reflect light “specularly”, i.e., in the plane of incidence, the angle of reflection is equal to the angle of incidence.2024PF80293

[0089] 11

[0090] In the present context, light incident on the first specularly reflective metallic mirror 124 refers to both any first laser light that has passed through the first polarization maintaining phosphor layer 122 as well as any first converted light incident thereon.

[0091] As will become clear later, the first specularly reflective metallic mirror 124 may preferably comprise a reflective metallic layer that does not induce a change (or at least induces a negligible change) in polarization on reflected light. For example, unpolarized light reflected by the first specularly reflective metallic mirror 124 may remain unpolarized, and linearly polarized light reflected by the first specularly reflective metallic mirror 124 may maintain its direction of polarization. Suitable examples of reflective metallic layers may include silver (Ag) and aluminum (Al), although other examples will be readily apparent to the skilled person.

[0092] That being said, it is noted that one known effect of a specularly reflective metallic mirror is that (dependent on a frame of an observer), circularly / elliptically polarized light may be observed to change (i.e., switch) its polarization rotation direction (e.g., change from circular left to circular right, or vice versa) following reflection by the first specularly reflective metallic mirror 124.

[0093] The first phosphor arrangement 120 may also comprise a heat sink 126 in thermal contact with the first specularly reflective metallic mirror 124. Specifically, the heat sink 126 may act to draw heat or thermal energy from the first specularly reflective metallic mirror 124 (and possibly the first polarization maintaining phosphor layer 122) and dissipate said heat or thermal energy to the surrounding environment. In particular, the first specularly reflective metallic mirror 124 (and the first polarization maintaining phosphor layer 122) may gain thermal energy, i.e., heat up, from the absorption of any incident first laser light and / or first converted light, which can cause the optical component(s) to increase in temperature. The heat sink 126 may thus help to control the temperature of said optical components and reduce a likelihood and / or prevent said optical components exceeding a safe temperature limit.

[0094] The first optical arrangement 110 is configured to direct the first laser light towards the first phosphor arrangement 120, i.e., towards the first side 121 of the first polarization maintaining phosphor layer 122. To achieve this, the first optical arrangement 110 may comprise one or more reflectors 125 configured to control the propagation direction of the first laser light and direct it towards the first phosphor arrangement 120. For example, the first optical arrangement 110 may comprise a first laser light reflector 125 configured to2024PF80293

[0095] 12

[0096] receive the first laser light (from the laser light source 105) and direct (i.e., reflect) it towards the first phosphor arrangement 120.

[0097] In some examples, the first laser light reflector 125 may comprise a dichroic beam splitter configured to reflect light within a predetermined wavelength range (and transmit light outside the predetermined wavelength range). In such examples, the first laser light reflector 125 may be configured such that the predetermined wavelength range is equal to or entirely includes the first wavelength range of the first laser light. In this way, the first laser light is reflected towards the first phosphor arrangement 120, while the first converted light is transmitted through the first laser light reflector.

[0098] The first laser light reflector 125 may additionally, or alternatively, comprise a polarizing beam splitter configured to reflect light of a predetermined (linear) polarization (and transmit light of a polarization perpendicular to the predetermined polarization). In such examples, the first laser light reflector 125 may be configured such that the predetermined polarization is the same as the polarization of the first laser light when incident on the first laser light reflector. In some scenarios, the first laser light may be first converted into the predetermined polarization before reaching the first laser light reflector 125, e.g., by passing the first laser light through a polarizing filter (not illustrated in Figure 1) or similar.

[0099] The first optical arrangement 110 further comprises a first reflective polarizer 130 which receives at least part of the first converted light.

[0100] The first reflective polarizer is configured to configured to reflect or transmit any incident light dependent on a polarization state of the incident light. Specifically, the first reflective polarizer 130 is configured to transmit (at least first converted) light of a first linear polarization, i.e., light with a polarization direction aligned along a first direction in a plane of the first reflective polarizer 130. Furthermore, the first reflective polarizer 130 is configured to reflect (at least first converted) light of a second linear polarization perpendicular to the first linear polarization, i.e., light with a polarization direction aligned along a second direction in the plane of the first reflective polarizer 130 perpendicular to the first direction. For example, when the first linear polarization corresponds to a linear vertical polarization direction, vertically polarized light incident on the first reflective polarizer 130 would be fully transmitted, whereas horizontally polarized light incident on the first reflective polarizer 130 would be fully reflected.

[0101] More generally, from a classical point of view, light incident on the first reflective polarizer 130 may be partially transmitted if the light has a component of polarization equal to the first linear polarization, where said polarization component for the2024PF80293

[0102] 13

[0103] light is transmitted. The remainder of the light, corresponding to a polarization component equal to the second linear polarization, is consequently reflected by the first reflective polarizer 130. Conceptually, the first reflective polarizer 130 may thus be thought of as a polarizing beam splitter where light incident on the first reflective polarizer 130 is split into two light rays / beams (i.e., transmitted light and reflected light) each possessing a respective polarization state of the first and second linear polarizations. Thus, unpolarized light incident on the first reflective polarizer is separated into two beams: transmitted light, and reflected light having a polarization orthogonal to the polarization of the transmitted light.

[0104] Particularly, as will be expanded on later, the light transmitted by the first reflective polarizer 130 forms the first arrangement light of the first optical arrangement 110.

[0105] For the proposed light generating system, the first reflective polarizer 130 receives first converted light from the first phosphor arrangement 120. This first converted light includes light directly emitted by the first polarization maintaining phosphor layer 122 and / or light reflected by the first specularly reflective mirror 124.

[0106] Thus, the first converted light produced by the first phosphor arrangement 120 is directed towards the first reflective polarizer. This may be achieved through appropriate positioning of the elements of the first optical arrangement and / or the use of one or more lenses and / or mirrors, e.g., forming part of the first optical arrangement 110, e.g., part of the first phosphor arrangement 120.

[0107] For example, the first optical arrangement 110 may comprise a lens 135 configured to collimate any light (including at least the first converted light) from the first phosphor arrangement 120. More specifically, the lens 135 may receive light from the first phosphor arrangement 120 and refract said light in order to produce an approximately parallel beam of light. Said parallel beam of light may then be directed towards the first reflective polarizer 130.

[0108] Furthermore, light reflected by the first reflective polarizer 130 is redirected towards the first phosphor arrangement 120. Thus, first converted light received from the first phosphor arrangement 120 is subsequently reflected by the first reflective polarizer 130 and directed back towards the first phosphor arrangement 120, forming reflect first converter light.

[0109] As polarizing beam splitters typically cannot reflect light at normal incidence, the first reflective polarizer 130 may comprise (in addition to an initial polarizing beam splitter) one or more mirrors, and / or one or more additional polarized beam splitting elements. Particularly, this combination may allow for the light reflected by the first2024PF80293

[0110] 14

[0111] reflective polarizer 130 to be directed back towards the first phosphor arrangement 120, e.g., by achieving a total reflection angle of approximately 180°, thereby approximately reversing the propagation direction of the reflected light compared to the incident light.

[0112] The first optical arrangement 110 further comprises a first achromatic quarter waveplate 140 arranged between the first phosphor arrangement 120 and the first reflective polarizer 130. The first achromatic quarter waveplate 140 is arranged / configured such that light from the first phosphor arrangement 120 (including the first converted light) and light reflected by the first reflective polarizer 130 (including the reflected first converted light) pass through the first achromatic quarter waveplate 140 before reaching / being received by the opposing optical element.

[0113] The first achromatic quarter waveplate 140 is configured to convert linearly polarized light into circularly or elliptical polarized light (and vice versa) dependent on the angle between the polarization direction of the incident light and a fast axis of the first achromatic quarter waveplate 140. In particular, when passing through the first achromatic quarter waveplate 140, polarization components perpendicular to the fast axis are retarded by 90° in phase compared to polarization components parallel to the fast axis. This thereby induces a rotationally varying polarization direction in incident linearly polarized light, thus converting the linearly polarized light into circularly or elliptical polarized light. This rotationally varying polarization direction can similarly be removed by appropriately passing the light through a further quarter waveplate.

[0114] The first achromatic quarter waveplate 140 is further configured to function independent of the wavelength of the incident light (at least for wavelengths within the visible spectrum), i.e., the polarizations for two light rays of different wavelengths are affected the same when passing through the first achromatic quarter waveplate 140. To achieve this, the first achromatic quarter waveplate 140 may comprise an achromatic birefringent material. A suitable example may include a combination of crystalline quartz and magnesium fluoride crystals, e.g., in an air-spaced design. Alternatively, the first achromatic quarter waveplate may comprise a stack of oriented polymeric layers.

[0115] Figure 2 shows a working example of the light generating system 100 being used to produce a beam of linearly polarized light. Specifically, Figure 2 illustrates an instance (e.g., pulse) of a first laser light 210 at different stages S1-S4 of manipulation to produce a first arrangement light 230 of a first linear polarization. In particular, a number of light rays are displayed in Figure 2 to schematically demonstrate the propagation of light within the light generating system 100.2024PF80293

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[0117] Note, though each stage of Figure 2 shows distinct / separate light rays, it will be understood that in a real -world scenario all light rays may be present simultaneously, e.g., when the first laser light 210 is provided to the first optical arrangement 110 continuously. Examples of this are illustrated for other (similar) light generating systems in Figures 3 to 6, which will be later disclosed.

[0118] At stage SI, the first laser light source 105 produces the (instance / pulse of) first laser light 210 which is received by the first phosphor arrangement 120. More specifically, the first laser light 210 may be directed towards the first laser light reflector 125, which subsequently acts to direct the first laser light 210 towards the first phosphor arrangement 120.

[0119] In the schematic of SI, prior to reaching the first phosphor arrangement 120, the first laser light 210 is illustrated as passing through the first achromatic quarter waveplate 140. Note, in a real scenario, this may not occur and instead the pathway of the first laser light 210 may be controlled such that the first laser light 210 bypasses the first achromatic quarter waveplate 140 in stage SI. More generally, however, in stage SI, the first laser light 210 may typically be unpolarized and thus would be unaffected / unchanged when passing through the first achromatic quarter waveplate 140.

[0120] At stage S2, the first phosphor arrangement 120 receives the first laser light 210, which is converted by the first polarization maintaining phosphor layer 122 into first converted light 220, which may be optionally reflected by the first specularly reflective metallic mirror 124 dependent upon the direction of emission by the first polarization phosphor layer. It will be noted that the first laser light 210 is either partially converted into the first converted light 220, with the remaining first laser light 210 being reflected away from the first phosphor arrangement 120, or is completely converted into the first converted light 220.

[0121] The first converted light 220 and any reflected (i.e., remaining) first laser light 210 are then directed towards the first reflective polarizer 130, e.g., through reflection from the first specularly reflective metallic mirror 124 and collimation from the lens 135. In particular, prior to reaching the first reflective polarizer 130, the first converted light 220 and the remaining first laser light 210 pass through the first achromatic quarter waveplate 140. Typically, in stage S2, the first converted light 220 and the remaining first laser light 210 are unpolarized (i.e., due to starting with an unpolarized first laser light) and thus are unaffected / unchanged by the first achromatic quarter waveplate 140.2024PF80293

[0122] 16

[0123] At stage S3, the first converted light 220 and the remaining first laser light 210 are received by the first reflective polarizer 130. Subsequently, each of the first converted light 220 and the remaining first laser light 210 are split according to their polarization states. Specifically, components of the first converted light 220 and the remaining first laser light 210 that are of a first linear polarization Pl are transmitted by the first reflective polarizer 130, i.e., pass through the first reflective polarizer 130. Conversely, components of the first converted light 220 and the remaining first laser light 210 that are of a second linear polarization P2 (perpendicular to the first linear polarization Pl) are reflected by the first reflective polarizer 130. In the case of (completely) unpolarized first converted light 220 and remaining first laser light 210, the two light beams are split by 50%, i.e., 50% is transmitted by the first reflective polarizer 130 and 50% is reflected.

[0124] The components of the first converted light 220 and the remaining first laser light 210 transmitted by the first reflective polarizer 130 form a portion of a first arrangement light 230, being light output by the light generating system 100 that is of the first linear polarization Pl. Furthermore, the wavelength range of the first arrangement light 230 (i.e., the range(s) of wavelengths comprised / covered by the first arrangement light 230) comprises the at least second peak emission wavelength (of the first converted light 220 transmitted by the first reflective polarizer 130) and may comprise the first peak emission wavelength (of the remaining first laser light 210 transmitted by the first reflective polarizer 130).

[0125] Accordingly, a perceived color of the first arrangement light 230 may be dependent on the relative combination of light transmitted by the first reflective polarizer 130 having second peak emission wavelength and the first peak emission wavelength. For example, when the first wavelength range covers a blue light range, and the second wavelength range covers a green light range, a yellow light range, and / or a red light range, the first arrangement light 230 may be perceived as white light.

[0126] The components of the first converted light 220 and the remaining first laser light 210 reflected by the first reflective polarizer 130 form a reflected light beam of the second linear polarization P2. Particularly, the reflected light beam is reflected back towards the first phosphor arrangement 120, and includes at least reflected first converted light.

[0127] Prior to reaching the first phosphor arrangement 120, the reflected light beam passes through the first achromatic quarter waveplate 140. Accordingly, as the reflected light beam is linearly polarized (i.e., of the second linear polarization P2) the reflected light beam is converted into circularly or elliptically polarized light, dependent on the orientation between the fast axis of the first achromatic quarter waveplate 140 and the polarization2024PF80293

[0128] 17

[0129] direction of the second linear polarization P2. For simplicity, in the present example, the reflected light beam is depicted as being converted into right-circularly polarized light CR.

[0130] At stage S4, the reflected light beam is received by the first phosphor arrangement 120. In the case where the reflected light beam (partially) comprises a portion of the first laser light 210, said portion may be (at least partially) converted into first converted light by the first polarization maintaining phosphor layer 122. Specifically, said first converted light may be emitted as unpolarized light similar to that emitted in stage S2 and will thus behave according to the previous disclosure. Therefore, to avoid repetition, such light will be ignored in the explanation of stage S4.

[0131] The received reflected light beam passes through the first polarization maintaining phosphor layer 122 and is reflected by the first specularly reflective metallic mirror 124. In this way, the first converted light having the second linear polarization direction is rotated to form further first converted light having the first linear polarization direction

[0132] Particularly, though the first polarization maintaining phosphor layer 122 negligibly affects the polarization of the reflected light beam, the handedness (i.e., polarization rotation direction) of the reflected light beam is reversed from right-circularly polarized CR to left-circularly polarized CL. Furthermore, the reflected light beam is directed towards the first reflective polarizer 130 and passed (again) through the first achromatic quarter waveplate 140.

[0133] From passing through the first achromatic quarter waveplate 140, the reflected light beam is converted from circularly polarized to linearly polarized light. More specifically, due to the change from right-circularly polarized light CR to left-circularly polarized light CL, the linear polarization direction of the reflected light beam is rotated 90° relative to the linear polarization direction of the reflected light beam prior to passing through the first achromatic quarter waveplate 140 in stage S3. Accordingly, this corresponds to the light reflected from the first polarization maintaining phosphor layer being converted to the first linear polarization PL Thus, upon being received by the first reflective polarizer 130, the reflected light is transmitted by the first reflective polarizer 130 and contributes towards the first arrangement light 230.

[0134] Through stages SI to S4, it can be seen how the first optical arrangement 110 may convert the first laser light 210 into the first arrangement light 230 of the first linear polarization PL In particular, the first optical arrangement 110 may effectively act as an2024PF80293

[0135] 18

[0136] optical cavity that confines light (e.g., the first laser light and the first converted light) and only emits light once it is of (or otherwise converted to) the first linear polarization Pl.

[0137] Furthermore, when preferably configured, the light generating system 100 may only lose light / energy due to absorption by one or more optical elements of the light generating system 100, e.g., where said light is converted into thermal energy. Particularly, when preferably configured, the efficiency of the light generating system 100 (i.e., the percentage of the first laser light 210 as produced by the first laser light source 105 that is converted into the first arrangement light 230) may be greater than 90%.

[0138] In the examples of Figures 1 and 2, the first laser light reflector 125 is depicted as being positioned between the first phosphor arrangement 120 and the first reflective polarizer 130. Furthermore, in stages S2 to S4, light rays are depicted as passing through the first laser light reflector 125 and being unaffected. Note, in a real scenario or alternative variants, this may not occur and instead the light rays may be directed to bypass the first laser light reflector 125, i.e., only the first laser light 210 as produced by the first laser light source 105 may encounter (i.e., intercept) the first laser light reflector 125.

[0139] In some examples, the first laser light reflector 125 may be configured such that the light rays in stages S2 to S4 are unaffected (or at least minimally affected) when passing through the first laser light reflector 125. For example, in cases where the first laser light 210 is entirely converted into the first converted light 220 in stage S2, the first laser light reflector 125 may be configured to only reflect (and thus only affect) the first laser light 210. For instance, the first laser light reflector 125 may be a dichroic beam splitter that is configured to only reflect light in the first wavelength range. Thus, first converted light 220 having the second peak emission wavelength in a second wavelength range different to the first wavelength range may be unaffected by the first laser light reflector 125, i.e., allowed to transmit through the first laser light reflector 125.

[0140] As a further example, the first laser light reflector 125 may be configured to only reflect light received in a specific direction, e.g., the direction facing the first laser light source 105. Accordingly, the light rays in stages S2 to S4 may be incident on the first laser light reflector 125 in a different direction that permits the light rays to be transmitted through the first laser light reflector 125.

[0141] Figure 3 shows an example of another light generating system 300 comprising the first laser light source 105 and the first optical arrangement 110.

[0142] Figure 4 shows an example of another light generating system 400. The light generating system 400 comprises the first laser light source 105 and the first optical2024PF80293

[0143] 19

[0144] arrangement 110 as previously disclosed. The light generating system 400 further comprises a first intensity beam splitter 405 and a second optical arrangement 410.

[0145] The first intensity beam splitter 405 is configured to receive the first laser light 210 and direct at least some of the first laser light 210 towards the first optical arrangement 110, and direct at least some of the first laser light 210 towards the second optical arrangement 410. In other words, the first intensity beam splitter 405 is configured to split the first laser light 210 into two light beams that are each directed towards a respective optical arrangement. In the present context, the first laser light 210 (prior to being split) and the two split beams all have the first peak emission wavelength in the first wavelength range.

[0146] Part of the laser light beam 210 transmitted by the beam splitter 405 directed towards the second optical arrangement 410 forms second laser light 510 . In this instance, the third peak emission wavelength is the same as the first peak emission wavelength, and the third wavelength band is the same as the first wavelength band. Thus, for this example, the second laser light has the first peak emission wavelength.

[0147] The first intensity beam splitter 405 may thus equivalently be described as being configured to convert at least some of the first laser light 210 into the second laser light 510 having the first peak emission wavelength. Accordingly, the second laser light 510 is provided to the second optical arrangement 410 and the unconverted first laser light 210 is provided to the first optical arrangement 110.

[0148] In some examples, the second laser light 510 and the unconverted first laser light 210 may be of equal intensity, i.e., each comprising half of the intensity of the initial first laser light 210.

[0149] The second optical arrangement 410 is configured to receive the second laser light 510 and convert (at least some of) the second laser light 510 into a second arrangement light 530 that is linearly polarized. In particular, the second arrangement light 530 differs from the first arrangement light 230 in terms of its polarization and / or its peak emission wavelength, i.e., the second arrangement light 530 is of a different linear polarization and / or has a different peak emission wavelength to that of the first arrangement light 230. To achieve this, the second optical arrangement 410 may comprise either of (or both of) a second phosphor arrangement 420 different to the first phosphor arrangement 120 and / or a second orientation of reflective polarizer 430 different to the first reflective polarizer 130.

[0150] The second phosphor arrangement 420 comprises a second polarization maintaining phosphor layer 422 (different to the first polarization maintaining phosphor layer 122) configured to receive the second laser light 510 at a first side of the second phosphor2024PF80293

[0151] 20

[0152] arrangement 420. For example, the second optical arrangement 410 may comprise a second laser light reflector 425 for directing the second laser light 510 (as received from the first intensity beam splitter 405) towards the first side of the second polarization maintaining phosphor layer 422.

[0153] The second polarization maintaining phosphor layer 422 is configured to convert at least some of the received second laser light 510 into second converted light 520 having a fourth peak emission wavelength in the second wavelength range. Additionally, the fourth peak emission wavelength is different to the first / third peak emission wavelength of the second laser light.

[0154] In some examples, the fourth peak emission wavelength is different to the second peak emission wavelength. For example, the second polarization maintaining phosphor layer 422 may comprise one or more different fluorescent materials to that of the first polarization maintaining phosphor layer 122, each configured to emit light having a different peak emission wavelength to the second peak emission wavelength (i.e., following absorption of the second laser light 510).

[0155] The second phosphor arrangement 420 further comprises a second specularly reflective metallic mirror 424 arranged at a second side of the second polarization maintaining phosphor layer 422 (i.e., opposite the first side). The second specularly reflective metallic mirror 424 is configured to reflect incident light, e.g., any of the second laser light 510 that has passed through the second polarization maintaining phosphor layer 422 and / or any of the second converted light 520 emitted by the second polarization maintaining phosphor layer 422 towards the second specularly reflective metallic mirror 424.

[0156] The second reflective polarizer 430 is configured to transmit incident light of a third linear polarization that is different to the first linear polarization and reflect light of a fourth linear polarization perpendicular to the third linear polarization. More generally, when incident on the second reflective polarizer 430, components of light that are of the third linear polarization are transmitted by the second reflective polarizer 430, whereas components of light that are of the fourth linear polarization are reflected by the second reflective polarizer 430. The second reflective polarizer 430 may thus split incident light into two light beams each of a respective polarization of the third and fourth linear polarizations.

[0157] Light of the third linear polarization transmitted by the second reflective polarizer 430 may contribute towards (i.e., form a portion of) the second arrangement light 530.2024PF80293

[0158] 21

[0159] In the example of Figure 4, the second optical arrangement 410 comprises both the second phosphor arrangement 420 and the second reflective polarizer 430.

[0160] Particularly, in this example, the second reflective polarizer 430 is configured to receive light from the second phosphor arrangement 420, i.e., the second converted light 520 emitted by the second transparent phosphor layer 422 and / or the second laser light 510 reflected by the second specularly reflective metallic mirror 424. In this regard, the second optical arrangement 410 may comprise a second lens 435 for collimating light (including at least the second converted light) received from the second phosphor arrangement 420 and directing it towards the second reflective polarizer 430.

[0161] The second optical arrangement 410 may also comprise a second achromatic quarter waveplate 440 for controlling the polarization of light in the second optical arrangement 410. More specifically, the second achromatic quarter waveplate 440 may be used in much the same way as the first achromatic quarter waveplate 140 to convert light reflected by the second reflective polarizer 430 from the fourth linear polarization to the third linear polarization, i.e., by utilizing reflection from the second specularly reflective metallic mirror 424. Said converted light may then be transmitted by the second reflective polarizer 430 to contribute towards the second arrangement light 530.

[0162] As an alternative, the second optical arrangement 410 may instead use or be partially formed from the first achromatic quarter waveplate 140 to convert light from the fourth linear polarization to the third linear polarization. More specifically, each of the first optical arrangement 110 and the second optical arrangement 410 may comprise a respective portion of the first achromatic quarter waveplate 140, e.g., a first portion and a second portion, respectively. Accordingly, light in the first optical arrangement 110 may pass through the first portion of the first achromatic quarter waveplate 140, and light in the second optical arrangement 410 may pass through the second portion of the first achromatic quarter waveplate 140.

[0163] According to the present example, the second arrangement light 530 is different from the first arrangement light 230 both in terms of its polarization and peak emission wavelength(s). Specifically, the second arrangement light 530 is of the third linear polarization, whereas the first arrangement light 230 is of the first linear polarization.

[0164] Additionally, the peak emission wavelength(s) of the second arrangement light 530 comprise(s) the third peak emission wavelength (and possibly the first peak emission wavelength), whereas the peak emission wavelength of the first arrangement light 2302024PF80293

[0165] 22

[0166] comprises the second peak emission wavelength (and possibly the first peak emission wavelength).

[0167] In another example, however, the second arrangement light 530 may be of the same polarization as that of the first arrangement light 230, i.e., the first linear polarization. In other words, the second arrangement light 530 may differ from the first arrangement light only in terms of its peak emission wavelength. Such an example may correspond to the second optical arrangement 410 comprising the second phosphor arrangement 420 and a reflective polarizer similar to (or the same as) the first reflective polarizer 130. Thus, the second optical arrangement 410 may not comprise the second reflective polarizer 430.

[0168] As another option, the second optical arrangement 410 may instead use the first reflective polarizer 130 for outputting second arrangement light 530 of the first linear polarization. In such an example, light from the second phosphor arrangement 420 may be provided to the first reflective polarizer 130.

[0169] More specifically, each of the first optical arrangement 110 and the second optical arrangement 410 may comprise a respective portion of the first reflective polarizer 130, e.g., a first portion and a second portion, respectively. Accordingly, light in the first optical arrangement 110 may be incident on the first portion of the first reflective polarizer 130, and light in the second optical arrangement 410 may be incident on the second portion of the first reflective polarizer 130.

[0170] In another example, the second arrangement light 530 may have the same peak emission wavelength(s) as the first arrangement light 230 but be of a different polarization, i.e., the fourth peak emission wavelength is may be the same (or substantially the same) as the second peak emission wavelength. Such an example may correspond to the second optical arrangement 410 comprising the second reflective polarizer 430 and a phosphor arrangement similar to (or the same as) the first phosphor arrangement 120. Thus, the second optical arrangement 410 need not comprise a separate second phosphor arrangement 420.

[0171] As another option, the second optical arrangement 410 may instead use the first phosphor arrangement 120 for (partially) converting the second laser light 510 into light having the at least one first converted peak emission wavelength. In such an example, the second reflective polarizer 430 may receive light from the first phosphor arrangement 120.

[0172] More specifically, each of the first optical arrangement 110 and the second optical arrangement 410 may comprise a respective portion of the first phosphor arrangement 120, e.g., a first portion and a second portion, respectively. Accordingly, light in the first optical arrangement 110 may be incident on the first portion of the first phosphor2024PF80293

[0173] 23

[0174] arrangement 120, and light in the second optical arrangement 410 may be incident on the second portion of the first optical arrangement 110.

[0175] In accordance with the previous examples, the light generating system 400 may also comprise one or more output reflectors 490 for combining the first arrangement light 230 and the second arrangement light 530, e.g., through constructive interference. For example, as shown in Figure 4, the one or more output reflectors 490 may be configured to control the propagation direction of the second arrangement light 530 (e.g., from one or more reflections) in order to combine it with the first arrangement light 230, e.g., by directing the second arrangement light 530 on to the path of the first arrangement light 230.

[0176] Each of the one or more output reflectors 490 may comprise any of a dichroic beam splitter and / or a polarizing beam splitter. Accordingly, the one or more output reflectors may be tuned to (only) reflect the second arrangement light 530 and (conversely) transmit the first arrangement light 230. For example, when the peak emission wavelength(s) of the second arrangement light 530 is / are different to that of the first arrangement light 230, the one or more output reflectors 490 may only reflect light in having the peak emission wavelength(s) of the second arrangement light 530. Thus, the first arrangement light 230 may be transmitted by the one or more output reflectors 490 (as depicted in Figure 4) allowing the first arrangement light 230 and the second arrangement light 530 to be combined.

[0177] Through combining the first arrangement light 230 and the second arrangement light 530, the overall light output by the light generating system 400 (i.e., the system light) may be modified, e.g., compared to just outputting either the first arrangement light 230 or the second arrangement light 530. For example, the first arrangement light 230 and the second arrangement light 530 may be combined to achieve a different overall linear polarization.

[0178] Additionally, or alternatively, the first arrangement light 230 and the second arrangement light 530 may be combined to achieve a different overall perceived color of light. For example, the combination of the first arrangement light 230 and the second arrangement light 530 may provide white light.

[0179] Figure 5 shows an example of another light generating system 500 comprising the first laser light source 105, the first optical arrangement 110, the second optical arrangement 410, and the one or more output reflectors 490. In particular, the light generating system 500 differs from the light generating system 400 of Figure 4 in terms of not comprising the first intensity beam splitter 405 and instead comprising a second laser light source 505.2024PF80293

[0180] 24

[0181] The second laser light source 505 is different to the first laser light source 105 and is configured to produce the second laser light 510. Thus, rather than producing the second laser light 510 from the first laser light 210, the example of Figure 5 comprises producing the second laser light 510 directly from another laser light source. Accordingly, the produced second laser light 510 may have a third peak emission wavelength (different to the first peak emission wavelength). The third peak emission wavelength may also be in the first wavelength range.

[0182] In accordance with the example of Figure 5, the second transparent phosphor layer 422 may be configured to absorb (at least some of) the second laser light 510 having the third peak emission wavelength. Subsequently, the second transparent phosphor layer 422 may be configured to emit second converted light 520 having the fourth converted peak emission wavelength different to the third peak emission wavelength (and possibly the first peak emission wavelength).

[0183] Figure 6 shows an example of another light generating system 600 comprising the first laser light source 105, the second laser light source 505, the first optical arrangement 110, the second optical arrangement 410, and the one or more output reflectors 490. The light generating system 600 further comprises a third laser light source 605 and a third optical arrangement 610.

[0184] The third laser light source 605 is different to the first laser light source 105 and the second laser light source 505 and is configured to produce a third laser light 710 separate to the first laser light 210 and the second laser light 510. Particularly, the produced third laser light 710 may have a fifth peak emission wavelength different to the first peak emission wavelength and / or the third peak emission wavelength. The fifth peak emission wavelength may be in the first wavelength range.

[0185] In an alternative example, rather than comprising the third laser light source 605, the light generating system 600 may comprise a second intensity beam splitter configured to receive either the first laser light 210 or the second laser light 510 and convert at least some of the received light beam into the third laser light 710. Accordingly, in such examples, the third laser light 710 may have either the first peak emission wavelength or the third peak emission wavelength depending on the peak emission wavelength of the received light beam.

[0186] The third optical arrangement 610 is configured to receive (at least some of) the third laser light 710 and output third arrangement light 730 of a linear polarization having a sixth peak emission wavelength (e.g., in the second wavelength range). In particular, the2024PF80293

[0187] 25

[0188] third arrangement light 730 may differ from the first arrangement light 230 and the second arrangement light 530 in terms of its polarization and / or its peak emission wavelength(s), i.e., the third arrangement light 730 is of a different linear polarization and / or has at least one different peak emission wavelength to that of the first arrangement light 230 and the second arrangement light 530.

[0189] According to the example of Figure 6, the third optical arrangement 610 comprises a third laser 605 passing through third polarizing beam splitter, polarisation maintaining diffusor 620 comprising metallic layer and a third quarter waveplate 640 (different to the first 140 and second 440 achromatic quarter waveplates). In particular, light received by the third optical arrangement 610 passes through the third quarter waveplate 640 to reach the polarisation maintaining diffusor 620, where it is reflected and directed through the third quarter waveplate 640 for a second time. The third optical arrangement 610 may also comprise a third lens 635 for collimating light prior to reaching (and following reflection by) the polarisation maintaining diffusor 620 comprising a metallic layer.

[0190] Reflected laser light from polarisation maintaining diffusor becomes diffused laser light (730) and upon going through the quarter lambda element linear polarisation direction of laser light becomes rotated by 90 degrees with respect to initial linear polarisation direction and become third arrangement light. Diffused light has a light intensity distribution which is different than the intensity distribution of laser light before it is reflected by a polarisation maintaining diffusor. Light intensity distribution of laser light upon reflection from the diffusor 620 may become a Lambertian light distribution.

[0191] Third arrangement light 730 reach the polarisation beam splitter and get combined with first arrangement light 230 and second arrangement light 530 to produce system light.

[0192] Thus, the third laser light 710 may be partially converted to a light beam of a fifth linear polarization by the polarized beam splitter 690, which forms a portion of the third arrangement light 730. The remaining (or unconverted) third laser light 710 of a sixth linear polarization may then be received by the third optical arrangement 610 and converted to the fifth linear polarization. The light output by the third optical arrangement 610 may then be added to the third arrangement light 730, e.g., using the polarized beam splitter 690.

[0193] The polarized beam splitter 690 may from part of (or otherwise be comprised by) one or more further output reflectors 690 configured to combine the third arrangement light 730 with the first arrangement light 230 and the second arrangement light 530, e.g., as depicted in Figure 6. In particular, the one or more further output reflectors 690 may be2024PF80293

[0194] 26

[0195] configured to only reflect the third arrangement light 730 (e.g., by only being sensitive to the wavelength range of the third arrangement light 730) and transmit the first arrangement light 230 and the second arrangement light 530.

[0196] The third arrangement light 730 may possess a different polarization and / or a different peak emission wavelength to that of the first arrangement light 230 and the second arrangement light 530. For example, when the fifth linear polarization is different to the first linear polarization and the third linear polarization, the third arrangement light 730 will be of a different polarization to that of the first arrangement light 230 and the second arrangement light 530. Furthermore, when the sixth peak emission wavelength is (at least) different to the second peak emission wavelength and the fourth emission wavelength (and possibly the first peak emission wavelength and the third peak emission wavelength) the third arrangement light 730 may have a different peak emission wavelength to that of the first arrangement light 230 and the second arrangement light 530.

[0197] Through combining the first arrangement light 230, the second arrangement light 530, and the third arrangement light 730, the overall light output by the light generating system 600 may be modified, e.g., compared to just outputting either the first arrangement light 230, the second arrangement light 530, or the third arrangement light 730. For example, the first arrangement light 230, the second arrangement light 530, and the third arrangement light 730 light may be combined to achieve a different overall linear polarization.

[0198] Additionally, or alternatively, the first arrangement light 230, the second arrangement light 530, and the third arrangement light 730 may be combined to achieve a different overall perceived color of light. For example, the combination of the first arrangement light 230, the second arrangement light 530, and the third arrangement light 730 may provide white light. This may correspond to an example where: the first laser light 210, the second laser light 510, and the third laser light 710 all comprise blue light, the first laser light 210 may be fully converted to first converted light comprising red light, the second laser light 510 may be fully converted to second converted light comprising yellow green light, and the third laser light may be fully converted to third converted light comprising green light.

[0199] Variations to the disclosed embodiments can be understood and effected by those skilled in the art 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.2024PF80293

[0200] 27

[0201] 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.

[0202] If the term "adapted to" is used in the claims or description, it is noted the term "adapted to" is intended to be equivalent to the term "configured to". If the term "arrangement" is used in the claims or description, it is noted the term "arrangement" is intended to be equivalent to the term "system", and vice versa.

[0203] Any reference signs in the claims should not be construed as limiting the scope.

Claims

2024PF8029328CLAIMS:

1. A light generating system (100, 300, 400, 500, 600) configured to provide, in operation, system light, the light generating system comprising:a first laser light source (105) configured to provide, in operation, first laser light (210) having a first peak emission wavelength, I, in a first wavelength range of from 400 nm to 490 nm; anda first optical arrangement (110) configured to receive the first laser light and output first arrangement light (230) which forms at least part of the system light, wherein the first optical arrangement comprises:a first phosphor arrangement (120) comprising:a first polarization maintaining phosphor layer (122) configured to receive the first laser light at a first side (121) of the first polarization maintaining phosphor layer, wherein at least part of the received first laser light is converted by the first polarization maintaining phosphor layer into first converted light (220) having a second peak emission wavelength, X2, in a second wavelength range of from 500 nm to 670 nm; anda first specularly reflective metallic mirror (124) arranged at a second side (123) of the first polarization maintaining phosphor layer, opposite the first side, the first secularly reflective metallic mirror being configured to reflect at least part of the first converted light;a first reflective polarizer (130) configured to receive at least part of the first converted light from the first phosphor arrangement, wherein the first reflective polarizer is configured to:transmit first converted light having a first linear polarization direction; andreflect first converted light having a second linear polarization direction which is orthogonal to the first linear polarization direction, wherein the reflected first converted light, having the second linear polarization direction, is directed towards the first phosphor arrangement; and2024PF8029329an achromatic quarter waveplate (140) arranged between the first phosphor arrangement and the first reflective polarizer, wherein:the first converted light having the second linear polarization direction and reflected by the first reflective polarizer passes through the achromatic quarter waveplate and is subsequently reflected by the first phosphor arrangement and passes through the achromatic quarter waveplate whereby the first converted light having the second linear polarization direction is rotated to form further first converted reflected light having the first linear polarization direction,wherein the further first converted reflected light having the first linear polarization is transmitted through the first reflective polarizer,wherein the first arrangement light comprises the first converted light having the first linear polarization direction and the further first converted reflected light having the first linear polarization direction.

2. The light generating system of claim 1, wherein the first optical arrangement further comprises a first laser light reflector (125) arranged between the first phosphor arrangement and the first reflective polarizer, wherein the first laser light reflector is configured to receive the first laser light from the first laser light source and direct the first laser light towards the first phosphor arrangement.

3. The light generating system of claim 2, wherein the first laser light reflector comprises a dichroic beam splitter configured to (i) reflect the first laser light and transmit the first converted light, or (ii) transmit the first laser light and reflect the first converted light.

4. The light generating system of any one of the preceding claims, wherein the first optical arrangement further comprises a lens (135) arranged between the first phosphor arrangement and the achromatic quarter waveplate (140), wherein:the first laser light from the first laser light source and light reflected by the first reflective polarizer pass through the lens before reaching the first phosphor arrangement, wherein the lens is configured to focus said light onto the first phosphor arrangement; and first converted light and further first converted light from the first phosphor arrangement passes through the lens before reaching the first reflective polarizer, wherein the2024PF8029330lens is configured to collimate the first converted light and further first converted light from the first phosphor arrangement towards the first reflective polarizer.

5. The light generating system of any one of the preceding claims, wherein the first polarization maintaining phosphor layer comprises a transparent phosphor layer.

6. The light generating system according to any one of the preceding claims, wherein the first polarization maintaining phosphor layer comprises a phosphor of the type A3B5O i2:Ce, wherein:A comprises one or more of Y, La, Gd, Tb and Lu; andB comprises one or more of Al, Ga, In and Sc.

7. The light generating system of any one of the preceding claims, wherein the first polarization maintaining phosphor layer comprises one or more refractive structures arranged at the first side and / or the second side of the first polarization maintaining phosphor layer.

8. The light generating system of any one of the preceding claims, wherein the first specularly reflective metallic mirror comprises: silver, aluminum, or any combination thereof.

9. The light generating system of any one of the preceding claims, wherein the achromatic quarter waveplate comprises a combination of crystalline quartz and magnesium fluoride crystals, or a stack of oriented polymeric layers.

10. The light generating system of any one of the preceding claims, wherein the achromatic quarter waveplate is achromatic in a wavelength range from 550 - 650 nm.

11. The light generating system of any one of the preceding claims, further comprising:a second laser light source (505) different to the first laser light source for producing a second laser light (510) having a second laser emission wavelength.a first laser light intensity beam splitter (405) configured to receive the first laser light and directed it to first polarisation maintaining phosphor and convert at2024PF8029331least some of the first laser light into first arrangement light (230) having the first peak emission wavelength; and transmit part of the laser light to a second optical arrangement a second optical arrangement (410) configured to receive the transmitted first laser light 510 and redirect it via a second reflector (425) to second phosphor and convert it to second arrangement light (490) which forms at least part of the system light, wherein the polarization and / or the peak emission wavelength of the second arrangement light are different to the polarization and at the peak emission wavelength of the first arrangement light; andone or more output polarizing reflectors or polarizing beam splitter (490) configured to combine the second arrangement light (530) with the first arrangement light (230).

12. The light generating system of claim 11, wherein the second optical arrangement comprises a second phosphor arrangement (420) different to the first phosphor arrangement, wherein the second phosphor arrangement comprises:a second polarization maintaining phosphor layer (422) configured to receive the second laser light at a first side of the second polarization maintaining phosphor layer, wherein at least part of the received second laser light is converted by the second polarization maintaining phosphor layer into second converted light (520) having at least one second converted a fourth peak emission wavelength in the second wavelength range different to the at least one first converted peak emission wavelength; anda second a second reflective polarizer (430) is configured to transmit second converted light with a second polarization and reflect second converted light with a first polarizationan achromatic quarter wave plate (440) is configured to change the polarisation of reflected second converted light with a first polarisation direction after getting reflected by secularly reflective metallic mirror (424) to second converted light with a second polarizationwherein second converted light with second polarisation forms the second arrangement light.

13. The light generating system of any one of claims 11 or 12, wherein the second optical arrangement comprises a second reflective polarizer (430), different to the first reflective polarizer, configured to receive at least part of the first converted light or second2024PF8029332converted light from the first phosphor arrangement or a second phosphor arrangement, wherein the second reflective polarizer is configured to:transmit first converted light or second converted light having a third linear polarization different to the first linear polarization, wherein the light transmitted by the second reflective polarizer forms the second arrangement light; andreflect first converted light or second converted light having a fourth linear polarization orthogonal to the third linear polarization, wherein the received light reflected by the second reflective polarizer is reflected towards the first phosphor arrangement or the second phosphor arrangement.

14. The light generating system of any one of claims 11 to 13, wherein each of the one or more output reflectors comprises: a dichroic beam splitter, a polarizing beam splitter, or any combination thereof.

15. The light generating system of any one of claims 11 to 14, further comprising:either:a third laser light source (605) different to the first laser light source and the second laser light source configured to produce, in operation, a third laser light (710) having a fifth peak emission wavelength in the first wavelength range; ora second intensity beam splitter configured to receive the first laser light or the second laser light and convert at least some of the first laser light or the second laser light into a third laser light having the first peak emission wavelength or the second peak emission wavelength;a third optical arrangement (610) configured to receive the third laser light and output third arrangement light (730), wherein the polarization and / or angular intensity distribution of the third arrangement light is different to the polarization and / or the angular intensity distribution of the third laser lightone or more further output reflectors (690) configured to combine the third arrangement light with the first arrangement light and the second arrangement light.

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