WO2010072589A1

WO2010072589A1 - Device and method for mixing light beams

Info

Publication number: WO2010072589A1
Application number: PCT/EP2009/066947
Authority: WO
Inventors: Detlef Gerhard
Original assignee: Siemens Aktiengesellschaft
Priority date: 2008-12-15
Filing date: 2009-12-11
Publication date: 2010-07-01
Also published as: DE102009025567A1

Abstract

The invention relates to a device (1) and to a method for mixing light beams. The device (1) comprises at least one light beam splitter surface (2-i) arranged at an angle to a light beam direction of light beams of different wavelengths (λ). Said light beam splitter surface (2-i) is provided to split the light beams incident thereon. Furthermore, reflective outer surfaces (3-1, 3-2) are provided that are arranged around the light beam splitter surfaces (2-i) and that reflect light beams incident thereon. A light mixture can be generated by the mixing device (1) without a time delay. The mixing device (1) can be used in particular in a lighting device, for example, a high-power lamp, a motor vehicle headlight, an operating lamp, or a flash lamp.

Description

description

Apparatus and method for mixing light rays

The invention relates to an apparatus and a method for mixing light beams of different wavelengths to produce a light mixture having a desired spectrum.

Light rays are mixed in many applications to produce a light mixture having a desired light spectrum. An example of a light mixture is white light, which is composed of a plurality of light beams of different wavelengths. A conventional approach to light mixing of light rays originating from different light sources having different wavelengths or spectra is to use optical lenses and diffusers. By way of example, light beams which originate from different light-emitting diodes LEDs with different wavelengths are bundled by optical lenses, so that a white light mixture is produced at a point of convergence. Even when using a diffuser, however, this light mixture is then still separable with the result that an optic with higher complexity must be used. The use of a diffuser also leads to losses.

Furthermore, it is known to use a fluorescence effect to produce white light based on light-emitting diodes. FIG. 1A shows a fluorescent layer F on which a light radiation having a wavelength λ1 originating from a light diode is incident. The light-emitting diode can emit radiation in the UV range, for example. This UV light is converted by the fluorescent layer F into white light L. The Nach- Here, however, part consists in the fact that the conversion of the UV light generated by the light-emitting diode into the white light L takes a relatively long time, with a time delay of several μs typically occurring. Fig. IB illustrates the occurring time delay. When a current is applied to the LED for generating the UV radiation at a time t0, a time delay occurs until the white light L is emitted from the fluorescent layer F. Therefore, this approach for producing a light mixture is not suitable in many applications, for example in fast flashlamps (which require nanosecond illumination).

It is therefore an object of the present invention to provide a device for mixing light beams and a method for mixing light beams which mix light beams of different wavelengths with almost no time delay.

This object is achieved by a device having the features specified in claim 1.

The invention provides a device for mixing light beams with:

(A) at least one light beam splitter surface arranged obliquely to a light beam direction of light beams of different wavelengths for splitting the light beams incident thereon; and with

(b) reflecting outer surfaces which are disposed around the light beam splitter surfaces and which reflect the light beams incident thereon. The device according to the invention for mixing light beams offers the particular advantage that the mixed light formed can not easily be separated again, so that the optical further processing for a subsequent optical system can be carried out in a simple manner.

In addition, the device according to the invention for mixing light beams is characterized by a simple structural design.

In one embodiment of the device according to the invention, a plurality of light sources are provided which radiate light beams in different wavelength ranges. In this embodiment, the device not only performs a mixture of incident light beams, but also generates the light beam mixture itself.

In one embodiment of the device according to the invention, a first specular outer surface at a first inclination angle is arranged obliquely to the light beam direction of the light beams and a second specular outer surface is arranged at a second inclination angle obliquely to the light beam direction of the light rays.

In a possible embodiment of the invention

Means for mixing light beams, the inclination angles of the first and second specular outer surfaces are identical, and the two specular outer surfaces are arranged in parallel with each other.

In an alternative embodiment of the device according to the invention, the angles of inclination of the first and second reflecting outer surfaces are different and the two reflecting outer surfaces run apart at an angle. In one possible embodiment of the device according to the invention, at least one light beam splitting surface has an angle of inclination which lies between the inclination angle of the first specular outer surface and the inclination angle of the second specular outer surface.

In a possible embodiment of the device according to the invention, a plurality of light beam splitter surfaces are provided, which are arranged parallel to one another.

In one embodiment of the device according to the invention, a first translucent end plate is provided, through which the light beams of different wavelengths enter and there is provided a second translucent end plate, through which the mixed light rays exit.

This embodiment offers the particular advantage that scattering at the beam splitter surface ends is reduced. At the same time, the end plates offer the advantage that the device is protected against contamination.

In one possible embodiment of the device according to the invention, the light sources are connected to a controller which controls the intensity of the light beams emitted by the light sources.

This embodiment has the advantage that the spectrum of the generated light mixture can be adjusted and adapted to the particular application. In one possible embodiment of the device according to the invention, the light sources used are light-emitting diodes.

In one possible embodiment of the device according to the invention, the light beam splitting surfaces are coated glass plates.

This embodiment has the advantage that the light beam splitter surfaces can be produced with little technical effort.

In one possible embodiment of the device according to the invention, the angle of inclination of the reflecting outer surfaces and the angle of inclination of the light beam splitter surfaces are each 45 °.

This embodiment offers the particular advantage that the efficiency in the generation of the light mixture is maximum.

In one embodiment of the device according to the invention, a further similar device for mixing light rays is mounted mirror-symmetrically on the device.

This embodiment has the advantage that the optical axis of the incident light and the optical axis of the exiting light mixture are not shifted from each other.

In one embodiment of the device according to the invention, the reflective outer surfaces are mounted in a thermally conductive body. This embodiment offers the particular advantage that also light sources with a high power can be used.

In one embodiment of the device according to the invention, the light sources emit light beams in different wavelength ranges, the wavelength ranges in each case being in a range from 300 nm to 2 μm.

The invention further provides an illumination apparatus having at least one device for mixing light beams of different wavelengths, each device for mixing light beams having at least one light beam splitter surface, which is arranged obliquely to a light beam direction of the light beams of different wavelengths and for dividing the incident thereon light beams, wherein each device for mixing light rays further comprises reflecting outer surfaces which are arranged around the light beam splitting surfaces and which reflect the light rays incident thereon.

In one possible embodiment of the lighting device according to the invention, the lighting device has a high-power lamp, a motor vehicle headlight, an operating light or a flashlamp.

The invention further provides a method of mixing light rays,

wherein incident light beams of different wavelengths are reflected at a first specular surface completely toward at least one light beam splitter surface which reflects a first portion of the light rays back to the first specular surface, a second portion the light rays pass through the light beam splitting surface to a second reflecting surface which completely reflects the light rays for mixing.

In a possible embodiment of the invention

Method, the light beams are generated by juxtaposed light sources and emitted in a direction to which the specular surfaces and the at least one light beam splitter surface obliquely.

In the following, embodiments of the device according to the invention for mixing light beams and the method according to the invention for mixing light beams will be explained with reference to the attached figures.

Show it:

Fig. IA, IB a conventional arrangement for generating a light mixture;

Fig. 2 shows an embodiment of the invention

Apparatus for mixing light beams;

3A, 3B, 3B signal diagrams for explaining the operation of the device according to the invention for mixing light beams;

4 shows a further embodiment of the device according to the invention for mixing light beams;

5 shows a further embodiment of the device according to the invention for mixing light beams; Fig. 6 shows another embodiment of the device according to the invention for mixing light beams.

As can be seen from FIG. 2, a device 1 for mixing light beams according to the invention has at least one light beam splitter surface 2. The light beam splitter surface 2 is, for example, a coated glass plate. The glass plate has a certain refractive index and is coated, for example, on one side with another material having a higher refractive index. The light beam splitter surface 2 may also be a coated film. A light beam striking the light beam splitter surface 2 is partially reflected, whereby a portion of the light passes through the light beam splitter surface 2 to a further, possibly behind arranged Lichtstrahlteilerfläche. The device 1 for mixing light beams further has reflective outer surfaces 3-1, 3-2, which are arranged around the at least one light beam splitter surface 2 around. The reflecting outer surfaces 3-1, 3-2 completely reflect the light beams incident on them. The mirror surfaces 3-1, 3-2 may be smooth mirror surfaces but also structured mirror surfaces. As shown in Fig. 2, the first specular outer surface 3-1 is disposed at a first inclination angle αl obliquely to the light beam direction of the incident light rays. The second specular outer surface 3-2 is disposed at a second inclination angle α2 obliquely to the light beam direction of the light rays that strike the light beam mixing device 1.

In the example shown in FIG. 2, light beams with four different wavelengths λ1, λ2, λ3, λ4 from below onto the luminous mixture 1 for mixing the light beams. The light beam splitter surface 2 has an inclination angle β. In addition, the light beam splitter surface 2 extends obliquely to the light beam incident direction of the incident light beams. The inclination angle β is between the inclination angle α1 of the first specular outer surface 3-1 and the inclination angle α2 of the second specular outer surface 3-2

{a, ≤β≤a ₂ ).

In one possible embodiment, the inclination angle α1 of the first specular outer surface 3-1 is identical to the inclination angle α2 of the second specular outer surface 3-2, and the two specular outer surfaces 3-1, 3-2 are arranged parallel to each other. In this case, the inclination angle β of the light beam splitter surface 2 is also equal to the angle αl, α2 of the two reflecting outer surfaces 3-1, 3-2 {a _i = β = a ₂ ). In one possible embodiment, the inclination angle α1, α2 of the two reflecting outer surfaces 3-1, 3-2 and the inclination angle β of the light beam splitter surfaces 2-i are each 45 °. In this embodiment, the efficiency for generating the light mixture L is maximum. The embodiment shown in Fig. 2 shows only a light beam splitter surface 2. In further embodiments, a plurality of light beam splitter surfaces 2-i are provided, which may be arranged in parallel to each other.

As shown in Fig. 2, the inventive device 1 for mixing light rays preferably a first translucent end plate 4-1 and a second translucent end plate 4-2. Through the first translucent end plate 4-1, the light beams of different wavelengths λ enter the device 1 for their mixing. About the second translucent End plate 4-2 exit the mixed light beams or the light mixture L. The light mixture L is, for example, a white light mixture. In one possible embodiment, the end plates 4-1, 4-2 are glued to the light beam splitter surfaces 2, so that the light scattering occurring at the ends of the light beam splitter surfaces 2 are reduced. Furthermore, the end plates 4-1, 4-2 serve to protect the device 1 according to the invention against contamination, since in the intermediate spaces, which see between the light beam splitter surfaces 2-i, can penetrate from the outside no dirt particles.

The spaces between the light beam splitter surfaces 2-i and between the light beam splitter surfaces and the reflective outer surfaces 3-i are filled with air in one possible embodiment. In an alternative embodiment, the spaces may also contain another medium, for example a transparent gas or transparent material with a certain refractive index.

In one possible embodiment, the medium present between the light beam splitter surfaces 2-i and in the two spaces between the outer light beam splitter surfaces and the exterior mirrors can be exchanged to optimize the optical properties of the mixing device or to adapt to the particular application.

In the embodiment shown in FIG. 4, the light beam splitter surface 2 is adhesively bonded to the two end plates 4-1, 4-2. In a possible alternative embodiment, the position of the light beam splitter surface 2 can be changed by lateral displacement. In the embodiment shown in Fig. 2, the light beam splitter surface 2 is formed by a coated glass plate.

In an alternative embodiment, the light beam splitter surface 2 is formed by one or more foils. In this embodiment, for example, the films can be clamped between the two end plates 4-1, 4-2.

In one possible embodiment of the device 1 according to the invention for mixing light beams, the light beam splitter surfaces 2-i, for example the gas plates or foils, are exchangeable or replaceable. For this purpose, the two end plates 4-1, 4-2 can be removed for a short time.

3A, 3B, 3B are diagrams for explaining the operation of the light beam mixing device 1 according to the present invention.

As shown in FIG. 3A, the device 1 is hit by beams of different wavelengths λ1, λ2, λ3, λ4, which are spatially separated from one another in the X direction. FIG. 3A shows the intensity distributions of the incident light rays. In one possible embodiment, the intensity distributions of the incident light beams may also overlap.

3B shows an approximately ideal course of the intensity distribution of the light mixture L formed by the device 1 according to the invention. In the example illustrated in FIG. 3B, the light mixture formed is a white light, the intensity of the different wavelengths λ1, λ2, λ3, λ4 over exit surfaces, that is flat in two dimensions, is approximately constant.

Fig. 3C shows a typical real λl course of the intensity distribution for different wavelengths, λ2, λ3, λ4 of the light mixture formed with a typical wave-shaped course of the intensity distributions for the different wavelengths _X1.

Fig. 4 shows an embodiment of the invention

Device 1 for mixing light beams. In this embodiment, the device 1 has three light beam splitter surfaces 2-1, 2-2, 2-3. The two reflective outer surfaces 3-1, 3-2 are each attached to a thermally conductive body 5-1, 5-2. The incident light beams having the different wavelengths λ1, λ2, λ3, λ4 are completely reflected at the first mirror surface 3-1 toward the three light beam splitter surfaces 2-1, 2-2, 2-3. Each light beam splitter surface 2-i reflects a first portion of the incident light rays back to the previous reflecting surface, with a second portion of the incident light rays passing through the respective light beam splitter surface 2-i to the next light beam splitter surface and finally to the second specular outer surface 3-2 - long, which completely reflects the light rays for mixing.

In one possible embodiment, the device according to the invention has light sources 6-1, 6-2, 6-3, 6-4, which radiate the light beams with different wavelength ranges. These light sources 6-i can be, for example, light-emitting diodes. These LEDs are mounted for example on a circuit board 7. In the embodiment illustrated in FIG. 4, the light sources 6-i emit light in different directions. different wavelength ranges. These wavelength ranges may each be, for example, in a range of 300 nm to 2 microns. In the embodiment shown in Fig. 4, the light sources 6-i are connected to a controller 8 which controls the intensity of the light beams emitted from the light sources 6-i. In this way, the spectrum of the light mixture L generated by the device 1 according to the invention can be adjusted for the particular application.

Fig. 5 shows a further embodiment of the device 1 according to the invention for mixing light beams. In this embodiment, the reflective outer surfaces 3-1, 3-2 are attached to a thermally conductive body 5. This thermally conductive body 5 is made of ceramic or metal, for example. The conductive body 5 may additionally comprise cooling ribs or cooling bands. In one possible embodiment, the thermally conductive body 5 is connected to the circuit board 7 shown in FIG. 4 and dissipates the heat generated by the light sources 6-i. In the heat sink 5, as shown in Fig. 5, holes 9-1, 9-2 may be provided for mounting. In one possible embodiment, the body 5 can be mounted on a holding apparatus by means of the bores 9-1, 9-2. In the embodiment shown in FIG. 5, the device 1 is for mixing

Light beams with or without end plates 4-1, 4-2 mountable to a holding apparatus.

FIG. 6 shows a further exemplary embodiment of the device according to the invention for mixing light beams. In this embodiment, to a first device IA for mixing light beams, a further, similar device IB for the mixing of light rays is mounted mirror-symmetrically. The first mixing device IA has a first one Heatsink 5A and the second mixing device IB a second heat sink 5B. The two mixing devices IA, IB are, as shown in Fig. 6, mounted mirror-symmetrically to each other. The embodiment shown in FIG. 6 offers the particular advantage that the optical axis of the incident light or of the incident light beams of different wavelengths λ1, λ2, λ3, λ4 and of the exiting light mixture L are not shifted relative to each other. This facilitates the assembly of the device 1 according to the invention and the adjustment of further optical components which are upstream or downstream of the light mixer 1 according to the invention.

The light mixer 1 according to the invention or the device 1 according to the invention for mixing light beams, as shown in the exemplary embodiments according to FIGS. 2, 4, 5, 6, can be used in many ways. In one possible embodiment, the device 1 according to the invention is provided for mixing light beams in a lighting device. This lighting device may be, for example, a high-power lamp, a car headlight, a surgical light or a flash lamp. The light mixing is done in the inventive device 1 for mixing light beams immediately without time delay. The device 1 according to the invention for mixing light beams can be produced in a simple manner and can be miniaturized in a simple manner. The light mixture L formed by the device 1 according to the invention is a homogeneous light mixture which is almost inseparable, so that the further optical processing of the light mixture can be carried out with little technical effort.

Claims

claims

1. Device (1) for mixing light beams with:

(A) at least one light beam splitter surface (2) arranged obliquely to a light beam direction of light beams of different wavelengths (λ) for splitting the light beams incident thereon; and with

(B) reflecting outer surfaces (3) which are arranged around the light beam splitter surfaces (2) and which reflect the incident light rays thereon.

2. Device according to claim 1, wherein a plurality of light sources (6) are provided which emit light rays in different wavelength ranges.

3. Apparatus according to claim 1 or 2, wherein a first specular outer surface (3-1) at a first inclination angle (αi) is arranged obliquely to the light beam direction of the light beams and a second specular outer surface (3-2) at a second inclination angle (0 (2) is arranged obliquely to the light beam direction of the light beams.

4. The device according to claim 3, wherein the inclination angles (αi, O (2) of the first and second specular outer surfaces (3-1, 3-2) are identical, and the two specular outer surfaces (3-1, 3-2) are parallel to - Are arranged one another.

The apparatus according to claim 3, wherein the inclination angles (αi, α ₂ ) of the first and second specular outer surfaces (3-1, 3-2) are different and the two reflecting outer surfaces run diagonally apart.

6. Apparatus according to claim 4 or 5, wherein the at least one light beam splitter surface (2) has an inclination angle (ß), the between the inclination angle (cxi) of the first specular outer surface (3-1) and the inclination angle (α ₂ ) of the second specular Outside surface (3-2) is located.

7. Apparatus according to claim 6, wherein a plurality of light beam splitter surfaces (2-i) are provided, which are arranged parallel to each other.

8. Apparatus according to claim 1-7, wherein a first translucent end plate (4-1) through which the light beams of different wavelengths (λ) enter, and a second translucent end plate (4-2) is provided, through which the mixed light beams ( 2) exit.

9. Apparatus according to claim 2-8, wherein the light sources (6) are connected to a controller (8) which controls the intensity of the light beams emitted by the light sources.

10. Apparatus according to claim 2-9, wherein the light sources (6) are light emitting diodes (LED's).

11. The device according to claim 1-10, wherein the light beam splitter surfaces (2-i) are coated glass plates.

12. The apparatus of claim 3-11, wherein the inclination angle (αi, α ₂ ) of the reflecting outer surfaces (3-1, 3-2) and the inclination angle (ß) of the light beam splitting surfaces (2-i) is 45 °.

13. The device according to claim 1-12, wherein the device (IA), a further similar device (IB) for the mixing of light rays is mounted mirror symmetrically.

14. The apparatus of claim 1-13, wherein the reflective outer surfaces (3-1, 3-2) are mounted in a thermally conductive body (5).

15. The apparatus of claim 2-14, wherein the light sources (6) emit light beams in different wavelength ranges (λ), each of which is in a range of 300nm to 2μm.

16. Lighting device with at least one device for mixing light beams according to claim 1-15.

17. The lighting device according to claim 16, wherein the lighting device comprises a high-power lamp, a motor vehicle headlight, a surgical lamp or a flashlamp.

18. A method for mixing light beams, wherein incident light beams of different wavelengths are reflected on a first reflecting surface (3-1) completely towards at least one light beam splitter surface (2-i) which forms a first portion of the light beam. rays to the first reflecting surface (3-1), wherein a second portion of the light rays passes through the light beam splitting surface (2-i) to a second reflecting surface (3-2) which completely reflects the light rays for mixing.

19. A method according to claim 18, wherein the light beams are generated by juxtaposed light sources (6) and radiated in a direction to which the specular surfaces (3-1, 3-2) and the at least one light beam splitter surface (2-i) are slanted run.