DE102017208469A1 - LIGHT MODULE FOR GENERATING MIXED LIGHT, HEADLAMP AND LIGHT - Google Patents

Abstract

The invention relates to a light module (10) for producing mixed light, in particular white light (32), with a light source unit (12) for emitting a first blue light beam (14a) which is irradiated onto a wavelength conversion element (18) which irradiates the incident light is converted into light having a dominant wavelength in at least one wavelength region different from blue, and radiates as a first converted light beam (14b), the light source unit (12) being configured to radiate a second light beam (16a), and wherein the light module (10 ) is configured such that a portion of a first optical path traversed by the first converted light beam (14b) is superposed with at least a portion of a second optical path traversed by the second light beam (16a, 16b); superimposed part of the first and second optical path an output (30) of the light module (10) provide len. In this case, the light module (10) has a scattering element (28) which is designed to radiate the second light bundle (16a) incident on the scattering element (28) as a second divergent light bundle (16b) in such a way that a radiation characteristic of the second divergent light bundle (16b) ( 16b) in a near field and in a far field within a certain tolerance with a radiation characteristic of the first converted light beam (14b) over.

Description

The invention relates to a light module for generating mixed light, in particular white light, wherein the light module has a light source unit which is designed to emit a first light beam in a first wavelength range and to radiate it to a wavelength conversion element, wherein the wavelength conversion element is designed to converting the wavelength conversion element by the first light beam irradiated light in the first wavelength range into light having a dominant wavelength in at least a second of the first different wavelength range, and to radiate the converted light as a first converted light beam. Furthermore, the light source unit is configured to emit a second light beam in a third wavelength range, wherein the light module is configured such that a first part of a first optical path, which is traversed by the first converted light beam, with at least a first part of a second optical path , which is traversed by the second light beam, is superimposed, and the superimposed first part of the first and second optical paths provide an output of the light module. Furthermore, the invention also relates to a headlamp and a luminaire with such a light module.

The present invention is particularly in the field of LARP (Laser Activated Remote Phosphor) based light sources. Light sources with high luminance in the fields of entertainment and medicine are currently dominated by classic lamps. In the case of headlamps with a small opening angle (the cone of light), discharge lamps are used because high luminances of more than 1000 candelas per square millimeter are required. Currently, light-emitting diodes (LEDs) only achieve luminance levels of up to about 200 candela per square millimeter. As an alternative to discharge lamps, LARP-based light sources are also available, which generate luminous intensities of several 1000 candelas per square millimeter and also enable lifetimes significantly higher than those of discharge lamps.

When using the LARP technology, white light is generally generated by the appropriate superposition of several individual spectral components. Such a LARP light source usually uses a blue laser beam which is irradiated onto a phosphor or a phosphor wheel. Different wavelength conversion elements, for example different phosphors, which convert the irradiated blue laser light into light of other wavelengths may be located on the phosphor wheel in different wheel segments. For example, a phosphor for generating red light, a phosphor for generating yellow light and a phosphor for generating green light can be located on the phosphor wheel in one segment. By rotating the wheel, the respective phosphors are sequentially illuminated by the blue laser light, thereby sequentially providing the various spectral components. Furthermore, on the phosphor wheel in a segment can also be a through hole, which can penetrate the blue laser beam without acting on a phosphor, so that it can be led to a suitable deflection on the same sub-path as the sequentially generated converted spectral components to an output. Thus, in a sequential process, spectral components of converted light are alternated with the direct blue of the laser diodes. The problem here, however, is that for many applications, the sequential color change is undesirable, e.g. for moving light sources, headlamps or lights, so-called moving heads in the entertainment area) or because of problems that arise in connection with the recording by video cameras. This problem can be remedied, for example, by irradiating light from a first laser light source onto a yellow phosphor, which is then superimposed with blue light from a second and separately provided laser light source.

However, in all cases, another problem arises, namely that sufficient beam homogenization of the ultimately combined light beam can not be provided. In the described method, color fringing usually occurs in the near field, in the far field or in the transition region. Furthermore, there is a dependence of the white point on the beam radius. By using methods for beam homogenization, for example by microlens arrays, light mixing rods or the like, these effects can be reduced somewhat, but often can not be reduced to an acceptable level.

It is therefore an object of the present invention to provide a light module for producing mixed light, in particular white light, by means of which mixed light with higher homogeneity is made possible.

This object is achieved by a light module having the features according to claim 1. Advantageous embodiments of the invention are the subject of the dependent claims, the description and the figures.

The light module according to the invention for producing mixed light, in particular white light, has a light source unit configured to radiate a first light beam in a first wavelength range and radiate it onto a wavelength conversion element, wherein the wavelength conversion element is adapted to convert the radiated to the wavelength conversion element by the first light beam in the first wavelength range in light, which has a dominant wavelength in at least a second of the first different wavelength range, and to radiate the converted light as a first converted light beam. In this case, the light source unit is further configured to emit a second light bundle in a third wavelength range, the light module being configured such that a first part of a first optical path, which is traversed by the first converted light bundle, with at least a first part of a second optical path , which is traversed by the second light beam, is superimposed, and the superimposed first part of the first and second optical paths provide an output of the light module. Furthermore, the light module has a scattering element, which is arranged in a second different from the first part of the second optical path, and which is adapted to radiate the incident on the scattering element second light beam as a divergent second light beam such that a radiation characteristic of the second divergent light beam in a far field and in a far field within a certain tolerance with a radiation characteristic of the converted light beam matches

The invention is based on the finding that the problem of mixed light homogeneity, and in particular also the white light inhomogeneity, is mainly due to the fact that the blue laser beam and the converted light differ significantly in their emission behavior or their emission characteristic. Both deviations of this emission characteristic in the far field and in the after field on the homogeneity of the ultimately combined light beam have a negative effect. This knowledge makes use of the invention by now the second light beam is irradiated onto a scattering element, by which it is possible that the second light beam is emitted as a divergent second light beam from this scattering element again, with a substantially same radiation characteristic like that of the converted first light bundle. Thus, it is advantageously possible for the combined light finally provided at the output to satisfy at least 90%, in particular at least 95%, certain requirements, for example with respect to color locus and maximum permissible deviation therefrom, of a specific application. This advantageously by the light module mixed light, in particular white light can be generated, which is always usable for any application or application to at least 90%, in particular 95%, as useful light.

In a subsequent combination, which is provided by the superimposition of the respective first parts of the first and second optical path, combined light, in particular white light, with a particularly high light homogeneity in the near and far field can be provided therewith.

The light source unit may include one or more laser light sources, such as laser diodes, for providing the first and second light beams. In general, the light source unit can provide the first and second light bundles simultaneously or temporally sequential. However, it is preferred that the light source unit is designed to provide the first and second light bundles simultaneously and via at least partially separate optical paths, so that the problem of the sequential color change can be advantageously avoided. This makes it possible to simultaneously illuminate the wavelength conversion element with the first light bundle and the scattering element with the second light bundle and accordingly also combine the light beams emitted again by the wavelength conversion element and the scattering element, for example by suitable deflection or combination optics, to form a common light bundle is provided corresponding to the first part of the first and second path. In addition, the second divergent blue light beam and the first converted light beam will still be collimated prior to their combination, for example by collimation optics. Furthermore, it is preferred that the first wavelength range and the third wavelength range are located in the blue, UV and / or violet wavelength range. In particular, the first and third wavelength ranges are preferably in the range between 365 nm and 475 nm. The provision of a first light bundle in such a wavelength range has the great advantage that most of the phosphors, and thus also the wavelength conversion element, are formed as such a phosphor or comprises such a phosphor, can be excited with an excitation radiation in such a wavelength range. The provision of the second light beam in this wavelength range, in particular in the blue wavelength range, has the advantage that blue light is suitable for generating white light, in particular in combination with yellow light, which is why preferably the second wavelength range of the converted light beam is located in the yellow wavelength range. So by a combination of the first converted light beam and the second, preferably blue, and scattered light beam white light Therefore, it is advantageous if the wavelength conversion element has a yellow phosphor or is formed as such, so that the first light beam incident on the wavelength conversion element is converted into light having a dominant wavelength in the yellow spectral range. Thus, advantageously, only a single phosphor, the yellow phosphor, and the combination of the converted yellow light with the second scattered, in particular blue, light beam, produce white light. Alternatively, however, there is also the possibility that the wavelength conversion element has different phosphors which convert the irradiated first light bundle into light having respectively different dominant wavelengths, for example in the red spectral range and in the green spectral range. This also makes it possible to generate white light by superposition with the blue second light beam.

However, the light module can not only be used for generating white light, but in the same way for the production of light of any color with a particularly high homogeneity. For this purpose, therefore, for example, the second wavelength range can be settled by suitable choice of the phosphor for the wavelength conversion element in other spectral ranges, for example in the red or green spectral range. Also, a plurality of wavelength conversion elements associated with different spectral regions may be provided. Likewise, according to the second light beam can be provided as light in spectral regions other than blue.

Regardless, i. In particular, for the generation of white light, the first and the third wavelength range may be the same, but also different from each other. For example, the first wavelength range may be in the range of 440 nm to 460 nm, and the third wavelength range may be in the range of 455 to 470 nm.

According to an advantageous embodiment of the invention, the emission characteristic of the first converted light beam is a first radiation distribution and the radiation characteristic of the second divergent light beam is a second radiation distribution. In particular, a radiation distribution in the near field means the location dependence of the irradiance, and in the far field the angular dependence of the light intensity , In this case, furthermore, the irradiance is defined as the luminous flux per area, while the luminous intensity is defined as the luminous flux per solid angle. Thus, the radiation distribution thus gives the distribution of the radiation as a function of a spatial coordinate, i. So either depending on a location coordinate or an angle to. Consequently, it is thus advantageously made possible by the scattering of the second light bundle at the scattering element that the emitted and scattered second light bundle has substantially the same light distribution as the converted first light bundle. Thus, the second light beam emitted by the scattering element can advantageously be provided with substantially the same angular dependence of the far field intensity and substantially the same spatial dependence of the near field irradiance as the converted first light beam emitted by the wavelength conversion element.

Furthermore, the first converted light beam as well as the scattered second light beam can also be emitted at substantially the same emission angles from the wavelength conversion element or from the scattering element, and also the source quantities, i. the areas from which the first converted light beam and the scattered second light beam are radiated may be substantially the same. In other words, the scattering element and the wavelength conversion element may be formed in coordination with each other so that the first converted light beam emitted from the wavelength conversion element is radiated from a first region of the wavelength conversion element at one time, and the light emitted from the scattering element at a time from a second region the scattering element is emitted, wherein a size of the second region differs from the size of the first region by less than a certain tolerance. The magnitudes of the respective first and second regions in this case define the source quantities of the converted light beam emitted by the wavelength conversion element and of the divergent second blue light beam emitted by the scattering element.

Thus, by substantially the same radiation distributions in the near field and in the far field for the divergent second light bundle, substantially the same emission angles and a substantially same source size can be achieved as for the converted first light bundle, which, as described, ultimately leads to a particularly high color homogeneity provided combined light beam leads.

According to a further advantageous embodiment of the invention, the emission characteristics of the second divergent light beam and of the converted light beam coincide within the specific tolerance such that the sum of all magnitude deviations of the normalized first radiation distribution from the normalized second radiation distribution is less than 10%, in particular less than 5%. , more preferably less than 1%, the average of the total radiation resulting from the respective normalized first and second radiation distributions. If the normalized first radiation distribution is denoted P _{1, n} (R) and the normalized second radiation distribution P _{2, n} (R), then this relationship can also be expressed as follows: $$\frac{{\displaystyle {\int }_{Rmin}^{Rmax}\left|{\text{P}}_{\mathrm{1,}\text{n}}\left(R\right)-{\text{P}}_{\mathrm{2,}\text{n}}\left(R\right)\right|dR}}{\frac{1}{2}{\displaystyle {\int }_{Rmin}^{Rmax}\left(\left({\text{P}}_{\mathrm{1,}\text{n}}\left(R\right)+{\text{P}}_{\mathrm{2,}\text{n}}(R\right)\right)dR}}\le 0.1insb,\mathrm{0.05,}insb\mathrm{.0,01.}$$

R here denotes the space coordinate. In the near field, the spatial coordinate denotes a location coordinate, for example x or y, in particular perpendicular to a main propagation direction of the respective light bundle, which then runs, for example, in the z-direction, in which case x, y refer to a Cartesian coordinate system. The integral limits Rmin, Rmax then designate -∞ and + ∞. In the far field, the space coordinate denotes an angle, for example α, with respect to the main propagation direction of the respective light bundles. The integral limits Rmin, Rmax then designate -90 ° and + 90 ° in this case.

Furthermore, the radiation distribution P _{1, n} (R), P _{2, n} (R) are normalized such that the respective maxima of the two distributions match in their value. For example, the maxima of the radiation distributions P _{1, n} (R), P _{2, n} (R) can be normalized to 1.

The term of the specific tolerance, as well as the term "essentially the same" used previously and subsequently, should preferably be understood in the sense of the above definition.

In order to achieve radiation characteristics which correspond to the type with respect to the first converted light beam and the scattered second light beam, numerous advantageous training possibilities of the scattering element come into consideration. Particularly good results can be achieved in particular by the embodiments of the scattering element described below.

According to an advantageous embodiment of the invention, the scattering element is designed so that the incident on the scattering element second light beam undergoes an elastic scattering process. As a result, it is advantageously possible for the second light bundle emitted by the scattering element and thus divergent to achieve the substantially same emission characteristic as for the first converted light bundle. Another great advantage of such an elastic scattering process is that the coherence properties of the blue laser light are also partially destroyed, which in turn allows speckle effects to be reduced.

In a further advantageous embodiment of the invention, the scattering element comprises as a material titanium dioxide and / or alumina and / or barium sulfate. These materials are advantageously capable of generating a similar radiation behavior as a phosphor, but without converting the wavelength. In addition, these materials are particularly temperature resistant, so they are also suitable for very high light outputs, as they can be provided by the light source unit.

In a further advantageous embodiment of the invention, the scattering element comprises as a material yttrium aluminum garnet. Yttrium aluminum garnet is suitable as a scattering element, since it is optically transparent in the blue spectral range and at the same time has a high refractive index.

The scattering materials mentioned, namely titanium dioxide, aluminum oxide, barium sulfate and yttrium aluminum garnet can be used individually or in combination. Furthermore, the scattering particles may be applied directly to a substrate or embedded in a suitable binding material.

In addition, due to the suitable choice of material composition, in particular of the already mentioned materials, layer thickness and possibly also used binding material, such as silicone, particularly well matched radiation characteristics can be provided, thereby optimizing the system, ie the radiation behavior of the second scattered light beam be adapted to the radiation behavior of the converted first light beam. Likewise, the source size of the second light beam emitted by the scattering element can be adapted to one another in an adapted manner to the source size of the first converted light beam emitted by the wavelength conversion element by the suitable choice of material composition and layer thickness. The size of the source in the case of light conversion by means of a phosphor results on the one hand by the size and distribution of the pump light, that is, the light beam irradiated on the phosphor, on the phosphor, and on the other by the spot broadening in the phosphor. This is to be understood as the effect that the radiating surface is larger than the surface of the blue excitation beam on the phosphor surface. By a suitable choice of the parameters described above, ie material or material composition and layer thicknesses, so advantageously for the scattered second light beam, the same source size, and the same radiation distribution in the near field and in the far field as be achieved for the converted first beam.

As an alternative to providing the scattering element with the materials described above, the scattering element may also be formed with a blue phosphor which converts the irradiated second light bundle into light of a different wavelength. The converted light can thus have a different wavelength than the irradiated second light beam. The irradiated second light bundle may, for example, be in a blue wavelength range and be converted by the blue phosphor into another blue wavelength range. However, the irradiated second light beam can also be, for example, in the UV range and be converted by the blue phosphor into light in a blue wavelength range. This also makes it possible to adapt the emission characteristic in the near field and far field of the emitted second light bundle to that of the converted first light bundle emitted by the wavelength conversion element.

According to a further advantageous embodiment of the invention, the light source unit is arranged such that a radiation power or a luminous flux of the first light beam is independent of a radiation power or a luminous flux of the second light beam adjustable and / or the radiation power or the luminous flux of the second light beam regardless of the radiation power or adjustable to the luminous flux of the first light beam. This can be done, for example, by providing the first light beam and the second light beam respectively by separate laser light sources. Furthermore, at least one of these laser light sources is adjustable in relation to the radiant power radiated by them or the luminous flux. By means of two different laser light sources for providing the first and second light bundles, it is advantageously made possible to vary the power ratio in both channels and thus to provide, for example, an active chromaticity control of the ultimately combined light.

In a further advantageous embodiment of the invention, the light module is set up in such a way that the second light bundle is irradiated onto the scattering element in an irradiation direction, the scattering element being set up in such a way that a main emission direction of the second divergent light bundle emitted by the scattering element is opposite to the direction of irradiation. The second light beam is thus reflected after passing through the scattering element and passes through this again. This may be accomplished, for example, by a back and reflective coating or other reflective element disposed on the back of the diffuser element. As a result, on the one hand a significantly better scattering of the second light beam can be achieved, since the scattering element is traversed twice by the light beam and thereby scattered, and on the other hand can be provided by the provision of a reflective coating at the same time an improved heat dissipation, for example by such a reflective element simultaneously as Heat sink is formed or a heat sink is disposed directly on such a reflective element. As a result, significantly higher powers can be achieved by the light module than, for example, with a transmissive geometry. An arrangement in transmission has in addition to the poorer heat dissipation also disadvantages in terms of light homogeneity, as in transmission also a large non-scattered blue component is included. Preferably, this also applies in the same way to the first light beam irradiated to the wavelength conversion element. This, too, is preferably radiated again as a converted first light bundle counter to its direction of irradiation, whereby the same advantages can also be achieved, namely a significantly better heat dissipation and the resulting possibility of achieving higher powers.

Alternatively, however, it is also possible to realize both the wavelength conversion element and the scattering element in transmissive geometry, so that they each pass through the corresponding first and second light bundles and are thereby converted or scattered, and then correspondingly as the first converted light bundle or divergent second Light beams are emitted in a Hauptabstrahlrichtung, which are then rectified with the respective irradiation directions. In order to achieve high performance and to ensure good heat dissipation, for example, sapphire substrates, in particular both for the wavelength conversion element and for the scattering element are.

In a further advantageous embodiment of the invention, a polarization beam splitter is arranged in the second optical path between the light source unit and the scattering element, wherein the light source unit is designed to provide the second light beam as linearly polarized light with a first polarization, and wherein the polarization beam splitter is designed to At least for the most part, to transmit light of only the first polarization and to reflect light with a second polarization, which differs from the first polarization by 90 °. Thus, by means of such a polarization beam splitter, the second blue light beam reflected by the scattering element can be easily separated from the incident second light beam, in particular if the irradiated second light beam and the scattered second light beam in the same wavelength range. The dichroic beam splitters commonly used for combination in the prior art are not suitable in this constellation. The invention makes use of the knowledge that the linearly polarized light provided by the light source unit has a statistically distributed polarization after scattering at the scattering element, for which reason advantageously a polarization beam splitter can be used for the beam combination, comprising at least part of the light reflected by the scattering element, ie the second divergent light beam, reflected, so that now this reflected portion can be combined with the converted first light beam. Moreover, it is advantageous if the light module has a depolarization element which is arranged between the polarization beam splitter and the output. This is especially advantageous when polarization-sensitive elements are used in a downstream optical system.

In the case of a UV source for the second light beam and a blue converter for the scattering element, a dichroic beam splitter is preferably used instead of the polarization beam splitter; a depolarization element is not advantageous since a blue converter already emits statistically polarized light.

In a further advantageous embodiment of the invention, the wavelength conversion element is arranged on a rotatable about a rotation axis wheel, wherein the wavelength conversion element is arranged annularly about the axis of rotation at a first distance from the axis of rotation. The arrangement of the wavelength conversion element on a rotatable wheel, which rotates in particular during the operation of the light module, so that different areas of the wavelength conversion element are sequentially illuminated by the first light beam temporally sequentially, has the great advantage that in turn significantly higher performance can be achieved since the average power of the first light beam is distributed over a larger area in the time average. As a result, the wavelength conversion element does not overheat even at very high power densities of the irradiated first blue light beam. The heat generated by irradiation of the wavelength conversion element can be dissipated much better over the larger surface of the wheel to the environment.

In a further advantageous embodiment of the invention, the scattering element may also be arranged on the wheel, in particular likewise annular around the axis of rotation and at a second distance from the axis of rotation, wherein the first distance is preferably greater than the second distance. In other words, the phosphor trace, i. the track with the wavelength conversion element, on the rotatable wheel radially outward than the track with the scattering element. This is advantageous because the thermal load in the converted channel is significantly greater and thus the power can be distributed over a larger swept area.

Alternatively, the wavelength conversion element and the scattering element can also be arranged statically.

Furthermore, the invention also relates to a headlamp or a luminaire with a light module according to the invention or one of its embodiments.

Further advantages and features will become apparent from the following description of embodiments with reference to the accompanying figures. In the figures, like reference numerals designate like features and functions.

• 1 eine schematische Darstellung eines Lichtmoduls zur Bereitstellung von weißem Licht, gemäß einem Ausführungsbeispiel der Erfindung; und
• 2 eine schematische Darstellung eines Rads als Träger für einen Leuchtstoff und eines Streuelements des Lichtmoduls aus 1, gemäß einem Ausführungsbeispiel der Erfindung.

Show it:

• 1 a schematic representation of a light module for providing white light, according to an embodiment of the invention; and
• 2 a schematic representation of a wheel as a carrier for a phosphor and a scattering element of the light module from 1 , According to an embodiment of the invention.

1 shows a schematic representation of a light module 10 according to an embodiment of the invention. The light module 10 has a light source unit 12 on which a first laser light source 14 , For example in the form of one or more first pump laser, in particular as an array of pump lasers with, for example, 5 laser diodes each having 2 W of optical power and a wavelength of 455 nm, and a second laser light source 16 , for example in the form of one or more second lasers, in particular as an array of lasers with, for example, 5 laser diodes each having 2 W of optical power and a wavelength of 455 nm. The first laser light source 14 is designed to be a first blue light beam 14a which refers to a wavelength conversion element, here as a yellow phosphor 18 is formed, is irradiated. To do this, the first blue light beam passes through 14a starting from the first laser light source 14 first a collimator 20a , for collimation of the first light beam 14a , an optic 22a for beam homogenization, eg in the form of a forward scattering element, a dichroic beam splitter 24 , which is designed to transmit light in the blue wavelength range, and light in other wavelength ranges, in particular in the yellow wavelength range to reflect, and at least one further optical element or an optical system 26a to the first light bundle 14a on the phosphor 18 to focus, as well as that of the phosphor 18 converted and re-emitted yellow light bundles 14b to collapse. This is the converted light beam 14b from the phosphor 18 Lambertsch radiated, ie in the entire half-space in relation to the main emission direction HA1 with a half opening angle α1 of +/- 90 °, of which in 1 only on the optical system 26a incident part is shown.

That of the second laser light source 16 provided second blue light bundles 16a on the other hand, it becomes a scattering element 28 irradiated. For this the second blue light beam passes through 16a starting from the second laser light source 16 also first a collimator 20b , an optic 22b for homogenizing the second blue light bundle 16a , as well as at least one optical element or optical system 26b to the second blue light beam 16a on the scattering element 28 to focus, and that by the scattering element 28 scattered and re-emitted divergent blue light bundles 16b to collapse. Due to the scattering element 28 Now it is advantageously possible that the emitted blue divergent light beam 16b in its emission to the radiation characteristic of the converted first light beam 14b adapt. The divergent second light bundle ultimately emitted by the scattering element with the same emission characteristic 16b is also radiated in a main emission direction and lambertsch, ie in the entire half space with respect to the main emission direction HA1 with a half opening angle α2 of +/- 90 °, of which in 1 again only the optical system 26b incident part is shown. Furthermore, the scattering element 28 designed so that the scattered and re-emitted light beam 16b especially in its radiation distribution in the near field as well as in the far field with that of the converted and emitted yellow light beam 14b matches. Phosphors have a radiation behavior that can be well described by a Lambert radiator. The scattering element 28 can now be advantageously designed so that the scattered and emitted blue light beam 16b at least approximately shows the angle-dependent intensity distribution of a Lambert radiator. By means of the spreading element 28 should a radiation characteristic of the emitted blue light beam 16b are generated, which thus essentially with the emission characteristics of the phosphor 18 radiated converted light beam 14b matches. By combining the scattered and subsequently by the optical system 26b collimated blue light beam 16b with the converted and also collimated yellow light beam 14b can be at the exit 30 of the light module 10 now advantageously white light 32 provide with a particularly high color homogeneity.

To a similar radiation behavior as the phosphor 18 can generate, in particular without converting the wavelength, the scattering element 28 For example, titanium dioxide, alumina, yttrium aluminum or else barium sulfate. These substances may be embedded in suitable binding materials, such as silicones, glasses or other transparent media. However, instead of being embedded in binding materials, the scattering particles may also be directly on a reflective support. Due to the suitable choice of material composition, layer thickness and possibly also a binding material used, such as silicone, the scattering element 28 be optimized so that for the scattered and re-emitted blue light beam 16b on the one hand, both the same source size as for the converted yellow light beam 14b , as well as due to the elastic scattering also a similar angular dependence of the light intensity as in the converted yellow light beam 14b results. Furthermore, preferably also the beam paths and optical components of the light module 10 chosen such that the steel diameter and the divergence are coordinated.

Since the material used for the spreading element 28 is elastically scattering, it does not change the central wavelength or dominant wavelength of the re-emitted light beam 16b opposite to the incident light beam 16a , Thus, a dichroic beam splitter can not be used now to diffuse from the diffuser 28 scattered blue light bundles 16b to divert this subsequently with the converted yellow light beam 14b to combine. Instead, however, advantageously the combination of the radiation can take place by utilizing the polarization properties of the radiation. For this purpose, the second laser light source 16 For example, p-polarized light ready, which parallel to the plane of incidence one in the beam path of the second beam 16a . 16b between the second laser light source 16 and the scattering element 28 located polarization beam splitter 34 is polarized. Furthermore, this polarization beam splitter 34 designed to this p-polarized light of the second blue light beam 16a to transmit and to reflect s-polarized light against it. In the elastic scattering of the blue light beam 16a through the scattering element 28 however, the polarization is not a conserved quantity. The scattered blue light bundle 16b is therefore statistically polarized when it returns to the polarization beam splitter 34 meets. The polarization beam splitter 34 lets turn the p polarized light components while passing the s-polarized component of the incident light in the direction of the output 30 distracts or reflects. Thus, advantageously, the s-polarized component of the scattered blue light beam 16b brought into superposition with the converted yellow light and at the output 30 as white light 32 to be provided.

In this embodiment, about 50% of the second laser light source can be used 16 provided blue radiation, while 50% back to the second laser light source 16 because p-polarized radiation is the polarizer 34 transmitted. However, this transmitted radiation in no way affects the laser diodes of the second laser light source 16 , as by the scattering process on the scattering element 28 and twice the optics for homogenization 22b the focusability of the laser radiation is minimized such that no power densities in the laser diodes of the second laser light source 16 generated, leading to damage to the second laser light source 16 could lead.

Despite the light loss due to the polarizer 34 in the direction of the second laser light source 16 transmitted light can be provided by the light module according to the invention and its embodiments, a very good overlaying and homogenization of the two channels. Alternative methods allow a significantly poorer homogenization or are limited in their power scalability, eg when using the phosphor in transmission.

If in the light module 10 Downstream optic polarization-sensitive elements can be used, with the help of an optional additional depolarizer 38 that of the polarization beam splitter 34 reflected light can be provided as light with a mixed polarization.

Furthermore, in this example, both the phosphor 18 as well as the scattering element 28 on a common and about a rotation axis A rotatable, reflective wheel 40 arranged, which in a plan view of the axis of rotation A again in 2 is shown schematically. The phosphor 18 is annular around the axis of rotation A of the wheel 40 and at a first radial distance R1 to the axis A arranged while the scattering element 28 also annular and around the axis of rotation A with a second radial distance R2 is arranged. The arrangement of these two tracks 18 . 28 is preferably selected such that the phosphor trace 18 the larger of the two radii R1 . R2 Since the thermal load in the converted channel is significantly larger and the power can be distributed over a larger swept area. Alternatively to such a bike 40 For example, at lower power densities and / or lower average powers, static converters, ie, wavelength conversion elements, and / or static scatterers may also be used.

Furthermore, the two different laser arrangements, ie the first pump laser light source, offer 14 and the second laser light source 16 , the possibility of active color locus control by varying the power ratio in both channels. Alternatively, instead of the two lasers 14 and 16 Also, a single laser are used, by an additional optics on the two channels, that is, the respective optical paths for irradiation on the phosphor 18 and the scattering element 28 , is split.

In principle, it is also conceivable to realize continuous white light sources with partially converting fluorescent wheels in transmissive geometry, but in such a construction, the performance is limited by the use of non-metallic substrates with lower thermal conductivity. In addition, the angular dependence of the light intensity is different, since the radiation in the blue channel can be only partially scattered, and also this does not provide any possibility for active regulation of the ratio between converted channel to blue channel.

Depending on the design of the light module 10 can the tracks shown here on the bike 40 that is the fluorescent trace 18 and the track with the scattering element 28 , also on different sides of the wheel 40 be arranged. Also, instead of scattering the radiation in the blue channel without wavelength shift, a combination of blue phosphor, for example with an emission wavelength between 440 nm and 460 nm, and entertaining laser diode, for example at 405 nm, can be used. The separation of pump light and converted light can then again due to the spectral separation using a dichroic mirror instead of the polarization beam splitter 34 respectively.

Overall, a continuous white light source can thus be provided by an inventive light module and its embodiments, which has a particularly high color homogeneity due to the ability to tune the radiation pattern and source size between blue channel and converted channel by providing a scattering element.

LIST OF REFERENCE NUMBERS

10

light module

12

Light source unit

14

first laser light source

14a

first light bundle

14b

converted first light beam

16

second laser light source

16a

second light bundle

16b

scattered second light bundle

18

fluorescent

20a

collimator

20b

collimator

22a

Optics for homogenization

22b

Optics for homogenization

24

dichroic beam splitter

26a

optical system

26b

optical system

28

scattering element

30

output

32

White light

34

Polarization beam splitter

38

depolarizer

40

wheel

A

axis of rotation

α1

first maximum radiation angle

α2

second maximum radiation angle

HA1, HA2

main radiation

R1

first distance

R2

second distance

Claims (12)

Light module (10) for generating mixed light, in particular white light (32), wherein the light module (10) comprises a light source unit (12) which is adapted to emit a first light beam (14a) in a first wavelength range, and to a wavelength conversion element (18), wherein the wavelength conversion element (18) is adapted to convert the light irradiated to the wavelength conversion element (18) by the first light beam (14a) into light in the first wavelength range which has a dominant wavelength in at least a second from the first Wavelength range, and to radiate the converted light as a first converted light beam (14b), wherein the light source unit (12) is adapted to emit a second light beam (16a) in a third wavelength range, wherein the light module (10) is designed such that a part of a first optical path, which is from the first n is converted by at least a part of a second optical path, which is traversed by the second light beam (16a, 16b), and the superimposed part of the first and second optical path an output (30) of the light module (10), characterized in that the light module (10) comprises a diffuser (28) disposed in a second different from the first part of the second optical path and adapted to irradiate the diffuser (28) irradiated on the diffuser (28) second light bundles (16a) as the second divergent light beam (16b) radiate such that a radiation characteristic of the second divergent light beam (16b) in a near field and in a far field within a certain tolerance with a radiation characteristic of the converted light beam (14b) over. Light module (10) after Claim 1 , characterized in that the emission characteristic of the first converted light beam represents a first radiation distribution and the emission characteristic of the second divergent light beam represents a second radiation distribution. Light module (10) after Claim 2 , characterized in that the radiation characteristics of the second divergent light beam (16b) and the converted light beam (14b) match within the certain tolerance such that the sum of all magnitude deviations of the normalized first radiation distribution from the normalized second radiation distribution is less than 15%, in particular less is 10%, more preferably less than 1%, of the average of the total radiation resulting from the respective normalized first and second radiation distributions. Light module (10) according to one of the preceding claims, characterized in that the scattering element (28) comprises as a material titanium dioxide and / or aluminum oxide and / or barium sulfate. A light module (10) according to any one of the preceding claims, characterized in that the diffuser (28) comprises as a material yttrium aluminum garnet. Light module (10) according to any one of the preceding claims, characterized in that the scattering element (28) and the wavelength conversion element (18) each comprise a same material, in particular yttrium aluminum garnet. Light module (10) according to any one of the preceding claims, characterized in that the light source unit (12) is arranged such that a radiation power or a luminous flux of the first light beam (14a) is independent of a radiation power or a luminous flux of the second light beam (16a) adjustable and / or the radiation power or the luminous flux of the second light bundle (16a) is adjustable independently of the radiant power or the luminous flux of the first light bundle (14a). Light module (10) according to any one of the preceding claims, characterized in that the light module (10) is arranged such that the second light beam (16a) is irradiated in a direction of irradiation on the scattering element (28), wherein the scattering element (28) so arranged in that a main emission direction (HA2) of the second divergent radiation beam (16b) emitted by the scattering element (28) is opposite to the direction of irradiation. Light module (10) according to one of the preceding claims, characterized in that in the second optical path between the light source unit (12) and the scattering element (28) a polarization beam splitter (34) is arranged, wherein the light source unit (12) is adapted to the second Light beam (16a) as a linearly polarized light having a first polarization, the polarization beam splitter (34) being adapted to transmit light of the first polarization at least substantially and light of a second polarization extending from the first polarization by 90 ° differs, to reflect. Light module (10) after Claim 9 , characterized in that the light module (10) has a Depolarisationselement (38) which is arranged between the polarization beam splitter (34) and the output (30). Light module (10) according to any one of the preceding claims, characterized in that the wavelength conversion element (18) on a about an axis of rotation (A) rotatable wheel (40) is arranged, wherein the wavelength conversion element (18) annularly about the axis of rotation (A) with a the first distance (R1) to the axis of rotation (A) is arranged, wherein the scattering element (28) on the wheel (40), annularly about the axis of rotation (A) and with a second distance (R2) to the axis of rotation (A) is arranged, in particular wherein the first distance (R1) is greater than the second distance (R2). Headlamp or luminaire with a light module (10) according to one of the preceding claims.

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