WO2012013434A1

WO2012013434A1 - Device and method for beam shaping

Info

Publication number: WO2012013434A1
Application number: PCT/EP2011/060698
Authority: WO
Inventors: Jürgen Wolf; Steffen Wagner
Original assignee: Jenoptik Laser Gmbh
Priority date: 2010-07-28
Filing date: 2011-06-27
Publication date: 2012-02-02
Also published as: DE102010038572A1

Abstract

The invention relates to a device for beam shaping (1) having a plurality of light sources (2₁, 2₂, 2₃, 2₄) disposed adjacent to each other, one first and one second reflection element (10₁, 10₂, 10₃, 10₄; 11₁, 11₂, 11₃, 11₄) being associated with each light source and each light source emitting a beam of rays (5₁, 5₂, 5₃, 5₄) along an emission direction, wherein the emitted beams of rays (5₁-5₄) lie in an emission plane and run parallel to each other, and the reflection elements (10₁-10₄; 11₁-11₄) are disposed so that the emitted beams of rays (5₁-5₄) are each reflected at the associated first reflection element (10₁-10₄) to the associated second reflection element (11₁-11₄) and are re-reflected by same, and the beams of rays coming from the second reflection elements (11₁-11₄) run parallel to each other and form a beam of rays (12) turning out jointly and running neither parallel nor perpendicular to the emission direction as seen in the perpendicular projection onto the emission plane.

Description

Apparatus and method for beam shaping

The present invention relates to a device for beam shaping of the beam of several light sources whose emitted radiation beam parallel to each other, and a corresponding method for beam shaping.

Such a device is known for example from DE 197 80 124 B4, wherein the upper side of the heat dissipation body is stepped, so that the juxtaposed light sources (here laser elements) emit their beams in different heights. These beams are then deflected with deflecting mirrors by 90 ° so that the individual beams lie directly above each other and form a common beam.

A disadvantage of this structure is on the one hand, that due to the stepped design of the heat sink, the heat dissipation is very inhomogeneous. There can be temperature differences of 1 to 4 and more from stage to stage. At a temperature dependence of the wavelength of the laser radiation of about 0.4 nm per ° C and a bandwidth of the emitted laser radiation of 3 to 4 nm, this leads to a significant and undesirable shift in the wavelength of the beam.

On the other hand, the production of such a stepped top of the heat sink is very expensive and possible only with an accuracy of about a few 10 μιη.

From US Pat. No. 6,229,831 B1, a device for beam shaping is known in which the individual light sources (in this case laser elements) are arranged via wedge elements on a planar upper side of a heat dissipation body. The wedge elements are chosen so that the inclination of the upper side is compensated relative to the horizontal, so that the individual laser elements emit their beams in the horizontal direction. In this embodiment, the adjustment by means of the wedge elements is expensive. Also, the heat dissipation due to the wedge members in each individual laser element is uneven, which is disadvantageous. In addition, the heat dissipation is degraded by the additional joints in the heat transfer path.

Proceeding from this, it is an object of the invention to provide an improved apparatus for beam shaping. Furthermore, a corresponding method for beam shaping is to be provided. The object is achieved by a device for beam shaping with a plurality of juxtaposed light sources, each of which a first and a second reflection element are assigned and each emit a beam along a radiation direction, the emitted beams lie in a plane of abstraction, parallel to each other and the reflection elements are arranged so that the emitted radiation beams each reflected at the associated first reflection element to the associated second reflection element, are reflected by this again and the coming of the second reflection elements beams parallel to each other and form a common outgoing beam, seen in the vertical projection on the Abstrahlebene neither parallel nor perpendicular to the emission direction.

In the beam shaping apparatus of the present invention, the light sources can be arranged on a planar portion of an upper surface of a heat dissipation body, so that excellent and homogeneous heat dissipation is possible. Furthermore, the size of the planar portion can be kept relatively low, so that the required footprint for a beam shaping device according to the invention can be kept small. Thus, an extremely compact beam shaping device according to the invention can be provided.

Preferably, the beam-shaping device comprises a heat-dissipating body with a top side, which has a planar section, on which the laser elements are arranged (preferably directly).

The planar or planar section of the upper side can be designed in particular as a continuous section. However, it is also possible that, for example, recesses are formed in the upper side between the juxtaposed laser elements, which result in that the planar section between the light sources is interrupted. It is preferable that the portions of the top surface of the heat sink on which the light sources are positioned lie in the same plane and thereby form the planar portion. It is Furthermore, it is preferred that the planar section is formed as a continuous or contiguous section of the upper side.

The light sources may in particular be laser elements and / or LED elements. The radiation emitted by the light source can be in the visible range, in the infrared range or in the UV range, so that the light source can also be referred to as a radiation source.

In the case of the beam-shaping device according to the invention, the common beam bundle (according to the principle of the device) preferably runs parallel to the plane section. Seen in cross section, the emergent beam may have a rectangular envelope or a parallelogram envelope.

The emergent beam can, viewed in perpendicular projection on the Abstrahlebene, with the emission of the emitting light source include an angle which is between 0 ° and 90 °. This angle can also be referred to as the azimuth angle.

In the beam shaping device according to the invention, neither the first reflection elements nor the second reflection elements are preferably arranged offset to one another in the emission direction. In particular, they are each arranged on a line, wherein the two lines can be parallel to one another. In each case, the reflection points of a central ray of the respective ray bundle can be considered as reference points.

In the beam shaping device according to the invention, the first reflection elements can be arranged so that the beams reflected at the reflection elements extend obliquely to the radiation plane. In particular, in each case the direction of the radiation beam incident on the first reflection element and the direction of the radiation beam reflected by the first reflection element can span a plane which is not perpendicular to the radiation plane.

Further, the second reflection elements can be arranged so that in each case the direction of the beam incident on the second reflection element and the direction of the beam reflected by the second reflection element span a plane which is not perpendicular to the radiation plane.

Furthermore, the second reflection elements, viewed in plan view of the radiation plane, can each be arranged directly above the associated first reflection element. However, it is also an offset possible. The first reflection elements can cause a deflection of the emitted radiation beams in the range of 60 ° to 120 °. These deflected beams can then be deflected by means of the second reflection elements in the range of 60 ° to 120.

Furthermore, the first and second reflection elements can each cause a deflection about a first or a second axis, wherein both axes include an angle from the range of 60 ° to 120 °, in particular of 90 °. The first and second reflection elements can be arranged in the beam shaping device according to the invention so that the emergent beam is parallel to the radiation plane. However, it is also possible that the emergent beam does not run parallel to the radiation plane. In the case of the beam-shaping device according to the invention, at least two of the first reflection elements and / or at least two of the second reflection elements can each be formed as a continuous component. For example, the reflection elements may be formed as individual surfaces of a copper mirror component. Of course, the reflection elements may also be separate elements.

The heat dissipation body may consist of a highly thermally conductive material, in particular copper or a copper alloy or aluminum or a composite material or have this. The reflection elements can be designed as metallic surfaces or as metallic or dielectric layers on a carrier material.

Preferably, the beam-shaping device has an optical focusing element which focuses the beam reflected by the second reflection elements. The focusing element is preferably refractive and may have one or more elements. Thus, for example, the coupling of the laser radiation in an optical fiber with, for example, round or rectangular, especially for example square cross section possible.

The device may have, for each light source between the light source and the associated first reflection element, at least one first optical element for collimating the radiation beam (eg in the fast-axis). The first optical element may be formed as a cylindrical lens or as a rotationally symmetrical lens. The lenses may be realized separately or, particularly in the form of cylindrical lenses, as individual segments of a coherent body. A rotationally symmetric lens is advantageously designed as a collimation for the fast-axis, while in the slow-axis because of the linear nature of the light or radiation source when using, for example, a semiconductor laser element after the first optical element still a divergence is present.

Furthermore, the device can have at least one second optical element for collimation (for example in the slow axis) for each light source between the light source and the associated second reflection element. The device may be configured so that the optical path from each light source to the associated second optical element is the same.

In the beam-forming device, the wavelength of the emitted beam may be in the range of about 190 nm to about 2000 nm, especially in the range of 250 nm - 2000 nm and in particular in the range of 600 nm to 1500 nm.

The laser elements are preferably semiconductor laser elements or laser diodes. The laser elements may be formed as separate laser elements and / or as laser bars. The laser elements are preferably designed as broad-band emitters, which emit a single-mode in fast-axis and multimode in slow-axis radiation. The laser resonators of these multimode laser elements are preferably designed as planar waveguides. The light exit surfaces of these laser elements represent linear beam sources. In this context, the term "parallel" is understood to mean, in particular, that a mathematically exact parallelism exists as far as possible. However, deviations in the single-digit range may be intentional or unintentional, which is still considered to be parallel. The heat-dissipating body can in particular be designed as a substantially plane-parallel plate or at least partially wedge-shaped.

The common outgoing beam has, seen in cross section, preferably an envelope, which is rectangular or square. Two or more of the beam-shaping device according to the invention may be provided such that the common outgoing beam bundles of the individual beam-shaping devices are superimposed to form a larger total beam. This can be realized for example for two beam-shaping devices by means of a partially transparent mirror or by means of a polarization-selective mirror which transmits a polarization direction and reflects a transmission direction orthogonal thereto. This can be the present Polarization of the respective common beam can be exploited. Of course, it is also possible to provide polarization-rotating elements, if necessary. Preferably, the polarization direction of the radiation of a beam-forming device is rotated by 90 °, while the polarization direction of the radiation of another beam-shaping device remains unchanged. Then, the beams of these two beam-forming devices can be combined with a polarization-selective mirror by one of the beams in transmission through the mirror passes you the other beam is reflected by an angle of preferably 90 ° to the mirror and the mirror paths of both beam-forming devices are superimposed after the mirror.

In the case of the beam-shaping device according to the invention, the beam or beams between the two reflection elements (ie the beam reflected by the first to the second reflection element) can coincide with the outgoing beam in a perpendicular projection onto the radiation plane.

There is further provided a method of beamforming the beams of a plurality of light sources (eg, laser elements and / or LED elements) each emitting a beam along a direction of radiation, wherein the emitted beams are in an abstraction plane and parallel to each other, wherein the Method of each of the emitted beams once around a first and then once deflected about a second axis so that the deflected beam parallel to each other and form a common outgoing beam, seen in perpendicular projection on the Abstrahlebene neither parallel nor perpendicular to the emission direction. The inventive method can be further developed in a similar manner as the development of the device according to the invention.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the specified combinations but also in other combinations or alone, without departing from the scope of the present invention.

The invention will be explained in more detail for example with reference to the accompanying drawings, which also disclose characteristics essential to the invention. Show it:

1 shows a schematic side view of a first embodiment of the beam-forming device according to the invention; Fig. 2 is a plan view of the beam-forming apparatus of Fig. 1, with the lenses 9 hidden;

FIG. 3 is a front view of the beam-forming apparatus of FIG. 1; FIG.

FIG. 4 is a front view of a laser element of the device of FIGS. 1 to 3; FIG.

Fig. 5 is a sectional view A-A of FIG. 2;

Fig. 6 is a schematic side view of a second embodiment of the beam-forming device according to the invention, and

Fig. 7 is a plan view of the beam-forming apparatus of Fig. 6, with the lenses 9 hidden;

In the embodiment shown in FIGS. 1 to 3, the beam-forming device 1 according to the invention comprises four light sources, which are formed here as semiconductor laser elements 2 2 ₂ , 2 ₃ and 2 ₄ and in an x-direction side by side on a planar portion D of a Top 3 of a heat dissipation body 4 are arranged. In the embodiment described here, the entire upper side 3 is planar. However, this is not mandatory.

The laser elements 2 2 ₄ each emit a laser beam 5i, 5 ₂ , 5 ₃ and 5 ₄ , which runs in the z-direction, so that the emission directions (each z-direction) of the individual laser elements 2 _r 2 ₄ are parallel to each other and the emitted radiation beams 5r5 ₄ lie in an emission plane which is parallel to the plane section D here. The laser elements 2 _r 2 _{4 used} are all the same and each comprise, as shown in Fig. 4 for the laser element, a waveguide 7, which has a plane perpendicular to the plane of the center line M and a rectangular cross-section. The height of the waveguide in the y-direction is about 3 μιη and the width in the x-direction is about 100 μιη. The emitted radiation beam here has a wavelength in the range of 630-1 100 nm.

The exiting beam 5 ^ typically has an elliptical beam cone (in the far field) in cross section, with the minor axis extending in the x direction. This direction is often referred to as a "slow axis", with the typical divergence angle in this direction often being about 7 to 15 degrees, the divergence angle in the y-direction, often called the "fast axis" is typically 90 ° (the x, y and z directions span a Cartesian coordinate system).

Since the emitter height along the y-direction of the laser element 2 2 _{4 is} only a few μιη, the emitted beam is by means of a first collimating lens 8 8 ₂ , 8 ₃ , 8 ₄ short focal length, which is often between 100 μιη and 1 .000 μιη , very well collimated so that the residual divergence of the beam after the first collimating lens 81-84 in the fast axis is very small. For this purpose, the first collimating lens 81 - 84 is preferably arranged at a very small distance in front of the beam exit surface of the laser element 2 2 ₄ , as indicated in FIGS. 2 and 3.

Further, for each of the laser elements 2 2 ₄ nor a second collimating lens 9i, 9 ₂ , 9 ₃ and 9 ₄ , a first deflection mirror 10 ^ 10 ₂ , 10 ₃ and 10 ₄ and a second deflection mirror 1 1 ^ 1 1 ₂ , 1 1 ₃ and 1 1 ₄ provided. To simplify the illustration, the second collimating lenses 9 _r 9 _{4 are} not shown in FIG. 2, and in FIG. 3 only the laser element 2 ₄ with the associated further optical elements (8 ₄ , 10 ₄ , 9 ₄ , 1 1 ₄ ) is shown , The reflecting surface of the first deflection mirror 10 _r 10 ₄ is preferably inclined by a = 45 ° relative to the y direction, as shown in FIG. 3 for the first deflection mirror 10 ₄ . The first deflecting mirrors 10r10 ₄ perform a deflection, so that the beams 5i -5 ₄ reflected at the first deflecting mirrors 10i-10 ₄ extend upwards (FIG. 1). In this case, the direction of the radiation beam 5r5 ₄ (ie the emission direction) impinging on the respective deflection mirror 10i -10 ₄ and the direction of the radiation beam reflecting at the respective deflection mirror 10r10 ₄ span a plane which is not perpendicular to the radiation plane (xz plane). One can also say that the reflected bundles of rays run diagonally to the plane of abstraction.

The thus deflected beams 5i -5 ₄ respectively through the associated second collimator lens 9 _r 9 ₄ , which performs a collimation of the slow-axis, and then hit the respective second deflection mirror ΐ ΐ 1 ₄ , which cause a deflection, so that the reflected beam 5r5 ₄ parallel to each other and parallel to the Abstrahlebene run. Together they form a failing beam 12 whose cross-section (section AA in FIG. 2) is shown in FIG. The individual reflected beams 5 5 ₄ are arranged parallel to each other so that the envelope U1 is a rectangle. Seen in plan view of the plane section D, the beam 12 with the emission direction (z-direction) includes an azimuth angle β between 0 ° and 90 ° (in this case about 80 °). In the embodiment shown in FIGS. 1 to 3, the second collimating lenses 9 9 ₄ each have the same distance to the upper side 3 of the heat dissipation body 4. Since the distance between laser element 21 -24 and associated first deflecting mirror 10i -10 ₄ for each laser element 2 _r 2 _{4 is the} same, this leads to the fact that the optical path length for all beam 5 _! -5 ₄ from the laser element 2 _r 2 ₄ to the corresponding second collimator lens 9 9 _{4 is the} same. Thus, a very compact beam-forming device 1 is provided which has an externally extremely small base area (size of the planar section D) and in which the emergent bundle of rays 12 has a rectangular envelope. Furthermore, a focusing lens 14 (shown in phantom and only shown in FIG. 2) may be provided for the beam 12, which serves to focus the emergent beam 12 so that it can be coupled into an optical fiber (not shown), for example.

The optical fiber may have, for example, a round or rectangular, in particular a square core cross-section.

FIGS. 6 and 7 show a second embodiment of the beam-forming device 1 according to the invention, wherein identical elements are designated by the same reference numerals and reference is made to the above explanations for their description. In the representation of Fig. 7 as the first deflecting mirror 10i -10 ₄ are almost completely obscured by the second deflecting mirror 1 1 I 1 1 and the drawn-ray beam 5i-5 _4, only the first deflecting mirror 10i is marked with a reference numeral. In Fig. 7, the lenses 9 are not shown. The embodiment according to Figures 6 and 7 differs from the embodiment according to Figures 1 to 3, characterized in that the first deflecting mirror 10r10 ₄ are oriented so that it deflects the incident beam 5i-5 ₄ by 90 ° in the y-direction. Therefore, the second deflecting mirror 1 V1 1 _{4 are positioned} directly above the respective associated deflecting mirror 10r10 ₄ . The second deflection mirror 1 1 i-1 1 are oriented so that the reflected beam while parallel to the plane section D, but not directly in the x direction. Seen in a vertical projection onto the radiation plane, the reflected beam bundles can enclose an angle with the emission direction (z direction), which is preferably between greater than 0 ° and less than 90 °. This angle can be referred to as the azimuth angle β.

In this embodiment, envelope of the beam cross section of the emergent beam 12 is no longer rectangular, but parallelogram-shaped. The deflection mirror 10i-10 ₄ and 1 1 i-1 1 ₄ may for example consist of solid metal material. It is also possible that the reflective surfaces of the deflection mirror 10i-10 ₄ , 1 1 1 _{4 are formed} as metallic or dielectric layers on a substrate.

Claims

claims

1 . Device for beam shaping (1) with

a plurality of juxtaposed light sources (2 2 ₂ , 2 ₃ , 2 ₄ ), which in each case a first and a second reflection element (10 ^ 10 ₂ , 10 ₃ , 10 ₄ ; 1 1 ^ 1 1 ₂ , 1 1 ₃ , 1 1 ₄ ) and each of which emit a beam (5!, 5 ₂ , 5 ₃ , 5 ₄ ) along a direction of emission, wherein the emitted beams (5! -5 ₄ ) are in an abstrahlebene, parallel to each other and the reflection elements (1 Οτ -10 ₄ ; IH ₄ ) are arranged so that

the emitted radiation beams (5! -5 ₄ ) in each case on the associated first reflection element (10i -10 ₄ ) to the associated second reflection element (IH ₄ ) reflected,

be reflected by this again

the radiation beams coming from the second reflection elements (1 1 _r 1 1 ₄ ) run parallel to one another and form a common emergent beam (12) which, viewed in perpendicular projection onto the radiation plane, is neither parallel nor perpendicular to the emission direction.

2. Apparatus according to claim 1, wherein the outgoing beam (12) seen in the vertical projection on the Abstrahlebene with the emission direction includes an angle which is between 0 ° and 90 °.

3. Device according to claim 1 or 2, wherein neither the first reflection elements (K 10 ₄ ) nor the second reflection elements (IH ₄ ) are arranged offset in the emission direction to each other.

4. Device according to one of the above claims, wherein the first reflection elements (10i -10 ₄ ) are arranged so that in each case the direction of the first reflection element (10i -10 ₄ ) incident beam (5i -5 ₄ ) and the direction of the beam reflected by the first reflection element span a plane that is not perpendicular to the radiation plane.

5. Device according to one of the above claims, wherein the second reflection elements (1 1 i -1 1 ₄ ) are arranged so that in each case the direction of the second reflection element (1 1 1 ₄ ) incident beam and the direction of the second Reflection element (1 1 _r 1 1 ₄ ) reflected beam span a plane that is not perpendicular to the Abstrahlebene.

6. Device according to one of the above claims, comprising a Wärmeableitkörper ( ₄ ) having a top (3) with a planar portion (D), wherein the light sources (5i -5 ₄ ) on the planar portion (D) are arranged.

7. Device according to one of the above claims, wherein the second reflection elements (1 1 1 -1 14), seen in plan view of the Abstrahlebene, respectively above the associated first reflection element (10i -10 ₄ ) are arranged.

8. Device according to one of the above claims, wherein the first reflection elements (I O1 -I O4) cause a deflection in the range of 60 to 120 °.

9. Device according to one of the above claims, wherein the second reflection elements (I I 1 -H 4) cause a deflection in the range of 60 ° to 120 °.

10. Device according to one of the above claims, wherein the first and second reflection elements (10i -1 0 ₄ , 1 1 1 - 1 ₄ ) are arranged so that the outgoing beam (12) extends parallel to the Abstrahlebene.

1 1. Device according to one of the above claims, wherein at least two of the first reflection elements and / or at least two of the second reflection elements are each formed as a continuous component.

12. Device according to one of the above claims, wherein a focusing element (14) is provided, which focuses the emergent beam (12).

13. Device according to one of the above claims, wherein for each light source (2 _r 2 ₄ ) between the light source (2 _r 2 ₄ ) and the associated first reflection element (10i -10 ₄ ), a first optical element (81, 8 ₂ , 8 ₃ , 8 ₄ ) for collimation of the beam (5i -5 ₄ ) is arranged.

14. Device according to one of the above claims, wherein for each light source (2 2 ₄ ) between the light source (2 _r 2 ₄ ) and the associated second reflection element (ΐ ΐ 1 ₄ ) at least a second optical element (9 9 ₂ , 9 ₃ , 9 ₄ ) for collimation of the beam (5r5 ₄ ) is arranged.

15. The apparatus of claim 14, wherein the optical path of each beam (5i -5 ₄ ) from the light source (2 2 ₄ ) to the associated second optical element (9 9 ₄ ) is the same.

16. The apparatus of claim 14 or 15, wherein the second optical element (9i -9 ₄ ) respectively between the first and second reflection element (10 ₁ -10 ₄ ; ΐ ΐ 1 ₄ ) is arranged.

17. Device according to one of claims 1 to 13, wherein a third optical element in the beam path after the second reflection elements (ΐ ΐ 1 ₄ ) is arranged, which collimates the radiation of the individual beams in the outgoing beam (12).

18. Device according to one of the above claims, wherein the light sources (2 2 ₄ ) are formed as laser elements.

19. A method of beamforming the beams of a plurality of light sources, each of which emits a beam along a radiation direction, wherein the emitted beams in an abstrahlebene and parallel to each other, wherein in the method each of the emitted beams once around a first and then once around a second axis is deflected so that the deflected beams are parallel to each other and form a common outgoing beam, seen in perpendicular projection on the Abstrahlebene neither parallel nor perpendicular to the emission direction.