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EP-4739943-A1 - HIGH FLUX LASER PHOSPHOR ENGINE WITH PARTIAL POLARIZATION BEAM SPLITTER AND TUNABLE COLOR POINT

EP4739943A1EP 4739943 A1EP4739943 A1EP 4739943A1EP-4739943-A1

Abstract

The invention provides a light generating system comprising one or more light generating devices, a luminescent material, a diffuser element, a polarization changing element, central optics, and a control system, wherein: (A) the one or more light generating devices are configured to generate device light; wherein the one or more light generating devices comprise light sources selected from a laser diode and a superluminescent diode; wherein the device light received by the central optics comprises a controllable polarization; (B) the luminescent material is configured to convert at least part of the device light received by the luminescent material into luminescent material light; (C) the diffuser element is configured to diffuse at least part of the device light received by the diffuser element thereby providing diffused device light while maintaining at least part of the polarization; (D) the polarization changing element is configured in an optical path of the device light between the central optics and the diffuser element; (E) the central optics comprises (i) a central optics polarizing beam splitter, and (ii) a central optics dichroic beam splitter; wherein the central optics are configured to transmit and/or reflect device light, diffused device light, and luminescent material light, received by the central optics in dependence of one or more of their polarizations and their spectral power distributions; (F) the control system is configured to control the polarization of the device light received by the central optics; (G) the light generating system is configured to provide system light comprising one or more of diffused device light and luminescent material light; and wherein the light generating system is configured such that in a first operational mode of the light generating system (a) at least part of the device light irradiates the luminescent material via the central optics, and the luminescent material light escapes from the light generating system via the central optics, and (b) at least part of the device light irradiates the diffuser element via the central optics, and at least part of the diffused device light escapes from the light generating system via the central optics.

Inventors

  • HOELEN, Christoph, Gerard, August
  • CORNELISSEN, HUGO, JOHAN
  • VDOVIN, Olexandr, Valentynovych

Assignees

  • Signify Holding B.V.

Dates

Publication Date
20260513
Application Date
20240620

Claims (15)

  1. 1. A light generating system (1000) comprising one or more light generating devices (100), a luminescent material (200), a diffuser element (710), a polarization changing element (810), central optics (900), and a control system (300), wherein: the one or more light generating devices (100) are configured to generate device light (101); wherein the one or more light generating devices (100) comprise light sources (10) selected from a laser diode and a superluminescent diode; wherein the device light (101) received by the central optics (900) comprises a controllable polarization; the luminescent material (200) is configured to convert at least part of the device light (101) received by the luminescent material (200) into luminescent material light (201); the diffuser element (710) is configured to diffuse at least part of the device light (101) received by the diffuser element (710) thereby providing diffused device light (711) while maintaining at least part of the polarization; the polarization changing element (810) is configured in an optical path of the device light (101) between the central optics (900) and the diffuser element (710); the central optics (900) comprises (i) a central optics polarizing beam splitter (910), and (ii) a central optics dichroic beam splitter (920); wherein the central optics (900) are configured to transmit and/or reflect device light (101), diffused device light (711), and luminescent material light (201), received by the central optics (900) in dependence of one or more of their polarizations and their spectral power distributions; the control system (300) is configured to control the polarization of the device light (101) received by the central optics (900); the light generating system (1000) is configured to provide system light (1001) comprising one or more of diffused device light (711) and luminescent material light (201); and wherein the light generating system (1000) is configured such that in a first operational mode of the light generating system (1000) (a) at least part of the device light (101) irradiates the luminescent material (200) via the central optics (900), and the luminescent material light (201) escapes from the light generating system (1000) via the central optics (900), and (b) at least part of the device light (101) irradiates the diffuser element (710) via the central optics (900), and at least part of the diffused device light (711) escapes from the light generating system (1000) via the central optics (900); and wherein one of the following applies: (i) the central optics polarizing beam splitter (910) is configured to (a) reflect x% of device light (101) having s polarization, (b) reflect y% of device light (101) having p polarization, and (c) transmit z% of device light (101) having p polarization, wherein x is selected from the range of at least 85%, wherein y is selected from the range of 25-85%, and wherein z is selected from the range of 15-75%; (ii) the central optics polarizing beam splitter (910) is configured to (a) reflect x% of device light (101) having s polarization, (b) reflect y% of device light (101) having p polarization, and (c) transmit z% of device light (101) having p polarization, wherein x is selected from the range of 15-75%, wherein y is selected from the range of at most 15%, and wherein z is selected from the range of at least 85%.
  2. 2. The light generating system (1000) according to claim 1, wherein the central optics polarizing beam splitter (910) is configured (al) to transmit and/or reflect at least part of the device light (101) and (a2) to transmit and/or reflect at least part of the diffused device light (711); and wherein the central optics dichroic beam splitter (920) is configured (bl) to transmit or reflect at least part of the device light (101), (b2) to transmit or reflect at least part of the diffused device light (711), and (b3) to reflect or transmit at least part of the luminescent material light (201) ; and wherein the polarization changing element (810) comprises a /4 waveplate.
  3. 3. The light generating system (1000) according to any one of the preceding claims, wherein the device light (101) has a wavelength selected from the blue wavelength range; wherein the luminescent material light (201) has a wavelength selected from the green-red wavelength range; wherein the system light (1001) in the first operational mode is white light; and wherein in the first operational mode the system light (1001) comprises for at least 90% diffused device light (711) and luminescent material light (201).
  4. 4. The light generating system (1000) according to any one of the preceding claims, further comprising a polarization control element (610) configured to control polarization of the device light (101); wherein the polarization control element (610) comprises a rotatable birefringent rotator; wherein the birefringent rotator comprises a X/2 waveplate; wherein the control system (300) is configured to control the polarization control element (610).
  5. 5. The light generating system (1000) according to any one of the preceding claims, wherein the one or more light generating devices comprise two different types of light generating devices (100), differing in the type of polarization of the device light (101) they generate; wherein the light generating system (1000) further comprises a first polarizing beam splitter (525), wherein the first polarizing beam splitter (525) is configured downstream of the two different types of light generating devices (100) and upstream of the central optics (900); and wherein the first polarizing beam splitter (525) is configured to transmit or reflect at least part of the p-polarized light, and to reflect or transmit at least part of the s-polarized light; and wherein the control system (300) is configured to control radiant fluxes of the device light (101) of the two different types of light generating devices (100).
  6. 6. The light generating system (1000) according to any one of the preceding claims, wherein the one or more light generating devices comprise two different types of light generating devices (100), differing in a spectral power distribution of the device light (101) they generate; wherein the light generating system (1000) further comprises a first dichroic beam splitter (515), wherein the first dichroic beam splitter (515) is configured downstream of the two different types of light generating devices (100) and upstream of the central optics (900); wherein the first dichroic beam splitter (515) is configured (a) to transmit or reflect at least part of the device light (101) of a first type, and (b) to reflect or transmit at least part of the device light (101) of a second type; wherein the control system (300) is configured to control radiant fluxes of the device light (101) of the two different types of light generating devices (100).
  7. 7. The light generating system (1000) according to any one of the preceding claims, wherein one of the following applies: (i) the central optics dichroic beam splitter (920) is configured (a) to transmit at least 80% of the device light (101) received by the central optics dichroic beam splitter (920), (b) to reflect at least 80% of the luminescent material light (201) received by the central optics dichroic beam splitter (920); and (c) to transmit at least 80% of the diffused device light (711), received by the central optics dichroic beam splitter (920); (ii) the central optics dichroic beam splitter (920) is configured (a) to reflect at least 80% of the device light (101) received by the central optics dichroic beam splitter (920), (b) to transmit at least 80% of the luminescent material light (201) received by the central optics dichroic beam splitter (920); and (c) to reflect at least 80% of the diffused device light (711), received by the central optics dichroic beam splitter (920).
  8. 8. The light generating system (1000) according to any one of the preceding claims, wherein the central optics polarizing beam splitter (910) is configured to (a) reflect x% of device light (101) having s polarization, (b) reflect y% of device light (101) having p polarization, and (c) transmit z% of device light (101) having p polarization, wherein x is selected from the range of at least 95%, wherein y is selected from the range of 50-85%, and wherein z is selected from the range of 15-50%.
  9. 9. The light generating system (1000) according to any one of the preceding claims, wherein the central optics polarizing beam splitter (910) is configured to (a) reflect x% of device light (101) having s polarization, (b) reflect y% of device light (101) having p polarization, and (c) transmit z% of device light (101) having p polarization, wherein x is selected from the range of 15-50%, wherein y is selected from the range of at most 5%, and wherein z is selected from the range of at least 95%.
  10. 10. The light generating system (1000) according to any one of the preceding claims, wherein the luminescent material (200) is configured in thermal contact with a thermally conductive material; wherein the light generating system (1000) comprises a plurality of light generating devices (100) configured to generate the device light (101), wherein two or more of the light generating devices (100) comprise laser light sources configured in a laser bank; wherein the light generating system (1000) further comprises one or more of integrating optics, collimation optics, and homogenization optics; wherein the luminescent material (200) at least comprises a luminescent material of the type AsBsOnT'e. 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; and wherein the device light (101) comprises blue device light (101).
  11. 11. The light generating system (1000) according to any one of the preceding claims, wherein the central optics (900) comprises (i) a single optical component having polarizing beam splitting functionality and dichroic beam splitting functionality, or (ii) two optical components, one having polarizing beam splitting functionality and one having dichroic beam splitting functionality.
  12. 12. The light generating system (1000) according to any one of the preceding claims, comprising a rotatable element (1200), wherein the rotatable element (1200) comprises the luminescent material (200); wherein during operation of the light generating system (1000) in the first operational mode the rotatable element (1200) rotates, such that over time different parts of the luminescent material (200) are irradiated by the device light (101).
  13. 13. The light generating system (1000) according to any one of the preceding claims, wherein the control system (300) is configured to control a spectral power distribution of the system light (1001) by controlling the polarization of the device light (101).
  14. 14. The light generating system (1000) according to claim 13, wherein the control system (300) is configured to control a correlated color temperature of the system light (1001) in dependence of one or more of a user interface, a sensor signal, and a timer; and wherein the control system (300) is configured to control in the first operational mode the correlated color temperature of the system light (1001) between 1800-8000 K.
  15. 15. A lighting device (1200) selected from the group of a lamp (1), a luminaire (2), a projector device (3), a headlamp, a photochemical reactor, and an optical wireless communication device, comprising the light generating system (1000) according to any one of the preceding claims.

Description

HIGH FLUX LASER PHOSPHOR ENGINE WITH PARTIAL POLARIZATION BEAM SPLITTER AND TUNABLE COLOR POINT FIELD OF THE INVENTION The invention relates to a light generating system. The invention further relates to a lighting device comprising the light generating system. BACKGROUND OF THE INVENTION Laser-phosphor based stage lighting engines are known in the art. For instance, WO2022143318 describes a light emitting device, comprising a first light source, a second light source, a dichroic mirror, a wavelength conversion apparatus, a first light path adjusting apparatus or a second light path adjusting apparatus, and a first scattering optical system. The light mixing effect of emergent light can be improved by using the first scattering optical system. Light emitted by the first light source is all used for exciting the wavelength conversion apparatus. SUMMARY OF THE INVENTION High brightness light sources can be used in various applications including spots, stage-lighting, headlamps, home and office lighting, and automotive lighting. For this purpose, laser-phosphor technology can be used, wherein a laser provides laser light and a remote phosphor converts laser light into converted light. A relatively straightforward way to produce white light using lasers is to use laser light in combination to generate phosphor converted light. Laser-phosphor systems may allow generation of high brightness light and may therefore be used in projection systems, including displays such as cinema projectors and projectors for home, school, and office applications, car front lighting, search lighting, stage lighting, architectural lighting, and special lighting applications. However, such light engine may be capable to generate only a single color point as defined by the luminescent converter. Creation of a product range providing different color points may be difficult as it may require multiple unique components to be designed, qualified, produced, and kept in stock. In other cases, e.g. in RGB LCD-based projection systems, the maximum brightness may be limited by the components used, the engine volume may be large due to the many components, and the system cost may be high due to the many dedicated components. A way to combine pump light and luminescent light may be to use a polarizing beam splitter for the pump light, by which part of the light is reflected to the luminescent material and part is transmitted to a diffuser. However, in general the diffused light may to a large degree be depolarized, which may result in relatively high losses of diffused blue light at the beam combiner where it is combined with the luminescent light into white output light. It may be possible for example to use a white light engine comprising a polarizing beam splitter configured to reflect (almost) all of s-polarized light and to transmit (almost) all of p-polarized light. In particular, such light generating systems may include a partially polarizing beam splitter with e.g. 20% transmission of the p-polarized light. Using such a partially polarizing beam splitter may provide a system with limited loss of light, however, it may also have a limited luminous flux as well as a fixed color point. It may be desirable to provide a light engine that can be easily factory calibrated with respect to requested color point and/or of which the color point can be easily adjusted by the user, while providing highly efficient collection of all the spectral contributions to the output light, resulting in a high efficiency high brightness white light engine. Hence, it is an aspect of the invention to provide an alternative light generating system, which preferably further at least partly obviates one or more of above-described drawbacks. The present invention may have as object to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative. According to a first aspect, the invention provides a light generating system (“system”) comprising one or more light generating devices, a luminescent material, a diffuser element, a polarization changing element, central optics, and a control system. In embodiments, the one or more light generating devices may be configured to generate device light. Especially, in embodiments, the one or more light generating devices may comprise light sources selected from a laser diode and a superluminescent diode. Further, in embodiments, the device light received by the central optics may comprise a controllable polarization. The luminescent material may, in embodiments, be configured to convert at least part of the device light received by the luminescent material into luminescent material light. Further, in embodiments, the diffuser element may be configured to diffuse at least part of the device light received by the diffuser element. Hence, in embodiments, the diffuser element may thereby provide diffused device light. The diffuser element may especially do so while maintaining at l