WO1994017576A1

WO1994017576A1 - Power-controlled fractal laser system

Info

Publication number: WO1994017576A1
Application number: PCT/DE1994/000037
Authority: WO
Inventors: Hans Opower; Helmut Huegel; Adolf Giesen; Friedrich Dausinger
Original assignee: Deutsche Forschungsanstalt für Luft- und Raumfahrt e.V.; Universität Stuttgart Institut für Strahlwerkzeuge
Priority date: 1993-01-22
Filing date: 1994-01-14
Publication date: 1994-08-04
Also published as: DE4490252B4; DE4490252D2; DE4301689A1; JPH07504788A; JP2683158B2

Abstract

A semiconductor laser system has several semiconductor laser units incorporating a laser oscillator for emitting laser radiation, optical fibers associated with each semiconductor laser unit, a coupling element which couples the laser radiation emitted by each semiconductor laser unit to the corresponding optical fiber, and a fiber bundle comprising the optical fibers as light waveguide system. Frome one end of the fiber bundle is emitted total laser radiation constituted by the sum of the coherent laser radiation generated by the semiconductor laser units which illuminates a target surface on an object to be irradiated when all semiconductor laser units are in operation. In order to improve such a semiconductor laser system so that complex irradiation tasks may be performed in a simple and most effective manner, a control system allows the power of each individual semiconductor laser unit to be controlled in a defined manner, and the irradiation intensity of different surface elements of the target surface to be predetermined in a defined manner for each surface element.__

Description

Power controlled fractal laser system

The invention relates to a semiconductor laser system with a plurality of semiconductor laser units comprising a laser oscillator, from each of which laser radiation emerges, with a light-conducting fiber assigned to each semiconductor laser unit, with a coupling element which couples the laser radiation emerging from the respective semiconductor laser unit into the respective light-conducting fiber , and with a fiber bundle comprising the fibers as a light guide system, which has an end from which emerges a total laser radiation formed by the sum of the coherent laser radiation generated by the semiconductor laser units, which illuminates a target surface from an object to be irradiated when all semiconductor laser units are lasered.

Such semiconductor laser systems are known, z. B. summarized seven semiconductor laser units to obtain total laser radiation with which an object can be irradiated.

With such semiconductor laser systems, however, only simple laser irradiation can be carried out.

The invention is therefore based on the object of improving a semiconductor laser system of the generic type in such a way that complex radiation tasks can be carried out in a simple and as effective manner as possible. This object is achieved according to the invention in a semiconductor laser system of the type described in the introduction in that a controller is provided with which the power of each individual semiconductor laser unit can be controlled in a defined manner and in that the controller can be given an irradiation of different surface elements of the target surface with an intensity which can be defined individually for each surface element.

The advantage of the present invention is thus to be seen in the fact that a defined intensity can be specified for each surface element of the target surface by means of the control, which is possible by controlling the power of each individual semiconductor laser unit.

The solution according to the invention thus makes it possible to carry out complex irradiation tasks and, for example, to irradiate different surface elements with different intensities within the target area in order to optimally adapt the type of irradiation of surface areas of the target area to the task to be solved in each case.

The solution according to the invention thus represents an advantageous application of the fact that the total laser radiation is not generated by one laser system but by several semiconductor laser systems and takes advantage of the fact that several semiconductor laser systems are used for this purpose, by defined control of the power of the respective semiconductor laser units perform complex radiation tasks. A particularly advantageous exemplary embodiment provides that the laser radiation emerging from each semiconductor laser unit has a laser radiation field which is independent of the intensity of the laser radiation of the other semiconductor units, so that it is possible in a particularly advantageous manner to define a definable intensity for each of the different surface elements of the target surface is.

This can be achieved even more advantageously if the laser radiation emerging from each semiconductor laser unit is decoupled from the laser radiation of the other semiconductor laser units, so that there is no radiation field interaction between the laser radiations from the individual semiconductor laser units and thus the adjustability of the intensity for each individual surface element is particularly advantageously possible.

In particular, it is provided that the laser radiation of a semiconductor laser unit coupled into the light-conducting fiber is decoupled from the laser radiation of the other semiconductor laser units in order to avoid radiation field interactions.

It can be implemented particularly expediently in that each of the semiconductor laser units has its own laser oscillator decoupled from the other semiconductor laser units.

A particularly advantageous decoupling of the laser oscillators is given when the laser oscillators of the semiconductor laser units are each laser oscillators that are separate from one another. Another particularly advantageous exemplary embodiment provides that the laser radiation forming the total laser radiation is decoupled from one another in a radiation field, so that there is no interaction of the laser radiation with one another via the radiation field in the total laser radiation, and thus there are no repercussions in the defined specification of the intensity of the individual laser radiation.

In particular, the solution according to the invention provides that the intensity of each individual semiconductor laser unit can be controlled in a defined manner with the control.

In addition, the wavelength of the laser radiation can also be controlled within certain limits in the case of semiconductor laser units, so that it is advantageous if the control enables the wavelength of the laser radiation of each individual semiconductor laser unit to be predefined in a defined manner.

With regard to the way in which the laser radiation from each semiconductor laser unit is guided through the fibers to the end of the light guide system and is combined to form the total laser radiation of the light guide system, no further details have so far been given. It is particularly advantageous if, in the region of the end of the light guide system, fiber end faces of the fibers from which the laser radiation of the associated semiconductor laser units emerges lie in an end face of the light guide system that can be optically mapped onto the target area. This is the prerequisite for being able to image all fiber end surfaces together with an optic on the target surface that the same imaging conditions apply to each fiber end face and thus a simple mapping applicable to all fiber end faces can be carried out.

This is particularly necessary when a high power density is to be achieved on the target surface, since the fiber end surfaces of the fibers should then be as close as possible to one another.

A particularly advantageous semiconductor laser system of the type according to the invention provides that an intermediate space between the fiber end faces in the end face is less than three times the fiber thickness. It is even more advantageous if the space between the fiber end faces is less than twice the fiber thickness and, in the case of particularly high power densities, it is provided that the fiber end faces lie next to one another in the end face, preferably adjoin one another.

With regard to the shape of the end face, no further details have been given in connection with the exemplary embodiments described so far. In the simplest case, it would be conceivable for the end surface to have the shape of a plane, since a plane can be easily mapped onto a target surface using standard imaging methods. However, it is particularly advantageous if the shape of the end surface is matched to a shape of the surface of the object to be irradiated or a surface of the object which is formed during the irradiation in the region of the target surface. In the context of the explanation of the exemplary embodiments described so far, no details were given as to how the laser radiation from the different semiconductor laser units should strike the target surface. An advantageous exemplary embodiment provides that the laser radiation from different semiconductor laser units impinges at least partially on different surface elements of the target surface, so that each surface element is assigned at least the laser radiation to one or more semiconductor laser units or to several semiconductor laser units.

For particularly complex radiation tasks, it is expedient if the laser radiation from different semiconductor laser units strikes different surface elements of the target surface, so that each surface element of the target surface is uniquely assigned a semiconductor laser unit whose laser radiation impinges on this surface element.

In order to achieve multiple irradiation of the surface elements, or to be able to achieve a higher intensity or other effects, in a further embodiment it is advantageously provided that the laser radiation of each semiconductor laser unit is partially on the target surface with the laser radiation of other semiconductor laser units is superimposed. Such an overlay need not only be an addition of the intensity. A coherent superposition of several laser radiations can also take place. As an alternative to this, it is advantageous for other types of irradiation tasks, in particular selective irradiation of the target area, if the laser radiation of each semiconductor laser unit irradiates one surface element of the target area with the laser radiation of the other semiconductor laser units without any superposition.

It is particularly expedient if an imaging optical system is provided between the end of the light guide system and the target surface so that defined imaging ratios between the end surface and the target surface can then be achieved.

In the simplest case, it is provided that the imaging optics image the fiber end surfaces in a ratio of one to one onto the image surface.

It is also conceivable, however, that the imaging optics represent the fiber end surfaces in a reduced size on the image surface, which is advantageous when achieving particularly high intensities, or that the imaging optics image the fiber end surfaces enlarged on the image surface by a large irradiated area, but with the loss of To maintain intensity.

In addition, it is advantageous if a shape of the end face is adapted to the optical imaging properties of the imaging optics. This means that with the shape of the end face not only an adaptation to the shape of the surface of the object in the region of the target area is possible, but that with the shape of the end face an adaptation to optical imaging properties of the imaging optics is possible, in order to compensate for example imaging errors of the imaging optics by the shape of the end face.

No further and more detailed information has so far been given with regard to the semiconductor laser units. In the simplest case, it is provided that each semiconductor laser unit comprises a single laser-active diode strip.

However, it is also conceivable that each semiconductor laser unit comprises several laser-active diode strips.

In order to obtain the highest possible power, it is advantageously provided that each semiconductor laser unit comprises a laser oscillator and a laser amplifier.

In order to obtain properties of the laser radiation that are as defined as possible, it is preferably provided that each semiconductor laser unit operates in a stabilized mode operation.

It is particularly expedient if each semiconductor laser unit operates in the transverse basic mode.

In addition, it is also advantageous if each semiconductor laser unit works in longitudinal single-mode operation.

With regard to the fibers from which the fiber bundle is formed, no further details have so far been given. An advantageous exemplary embodiment provides that the fibers are single-mode fibers. In the case of monomode fibers in particular, it is provided that the laser radiation is coupled into each monomole fiber with limited diffraction.

In connection with the explanation of the exemplary embodiments described so far, it was no longer considered which wavelength ranges the semiconductor laser units are designed for. For example, the simplest embodiment provides that all semiconductor laser units are designed for the same wavelength range.

However, it is also conceivable that different semiconductor laser units are designed for different wavelength ranges.

It is particularly expedient if the semiconductor laser units comprise a group of semiconductor laser units with the same wavelength.

Another advantageous exemplary embodiment provides that the semiconductor laser units comprise a plurality of groups of semiconductor laser units, each with the same wavelength.

In such a case, it is particularly advantageous if the fiber end surfaces of fibers emitting laser radiation of different wavelengths are combined to form one radiation group and if the radiation groups are arranged next to one another in the end surface. With such an exemplary embodiment, the marking and beam visualization can be realized particularly advantageously, because in this case only a group of semiconductor laser units need to be constructed in such a way that it generates the laser radiation with a wavelength lying in the visible range. In this case, the other group of semiconductor laser units can preferably be constructed such that it generates, for example, the laser radiation required for the irradiation or processing.

No further details have so far been given with regard to the coupling elements for coupling the fiber to the semiconductor laser unit. A particularly advantageous exemplary embodiment provides that an imaging element carried by the substrate of the semiconductor laser unit is provided as the coupling element for coupling the fiber to the semiconductor laser unit.

The grating is expediently a reflection grating.

Alternatively, it is conceivable to design the imaging element as a holographic-optical element.

Another alternative provides that the imaging element is a mirror molded into the substrate.

The mirror is preferably designed such that it focuses the laser radiation onto the fiber.

Another alternative provides that the imaging element is a lens integrated in the substrate. This lens can expediently be designed as an index lens.

In a further advantageous exemplary embodiment of the semiconductor system according to the invention it is provided that the fiber bundle comprises detector fibers, the detector fibers being used in particular to observe the target area. It is preferably provided that one end of the detector fibers lies at the end of the light guide system.

In order to achieve the same imaging ratios as in the case of total laser radiation, it is advantageously provided that the end of the detector fibers in the end face lies next to the fiber end faces, so that ultimately fiber end faces of the detector fibers also lie in the end face.

In this way, it can advantageously be achieved that the ends of the detector fibers are imaged on the target surface when using imaging optics.

In addition, the observation of the target area can be achieved particularly simply in that an optical detector for observing the image area is arranged at another end of the detector fibers.

This detector is preferably designed as a matrix detector, and the detector fibers are preferably assigned to the individual matrix points of the matrix detector in such a way that their fiber end faces enable the target area to be imaged directly on the matrix detector.

It is particularly expedient if a controller is provided which observes the intensity distribution in the target area via the matrix detector and ensures locally fixed irradiation on the object to be irradiated by means of a defined specification of the power for the individual semiconductor laser units within the target area. The laser system according to the invention preferably provides for a plurality of, for example, several tens or hundreds of semiconductor laser units with powers of 1 to 3 watts to be used in order to achieve powers of the total laser radiation of several hundred or even more than a thousand watts.

Further features and advantages of the invention are the subject of the following description and the drawing of some exemplary embodiments.

The drawing shows:

1 shows a perspective illustration of a first exemplary embodiment of a semiconductor system according to the invention;

2 shows a schematic illustration of a plan view of an end face of the light guide system in one variant;

3 shows a schematic top view similar to FIG. 2 in a second variant;

4 shows a schematic plan view of a target surface;

Fig. 5 is a schematic representation of individual

Components of a control according to the invention; 6 shows a schematic illustration of different intensity distributions within the target area;

7 shows a schematic illustration of different intensity distributions in the target area;

8 shows a schematic illustration of an adaptation of the fiber end surface to an imaging optics;

9 shows a schematic illustration of a semiconductor laser unit and the coupling of the laser radiation to a fiber in a first variant;

FIG. 10 shows a schematic illustration of the relationships in FIG. 9 in a second variant; FIG.

11 shows a schematic illustration of a semiconductor laser unit and the coupling of the laser radiation into a fiber in a third variant;

12 shows a schematic illustration of a second exemplary embodiment with different groups of semiconductor laser units;

13 shows a plan view of a fiber end face in a first variant of the second exemplary embodiment; 14 shows a plan view of a target surface in the first variant;

15 shows a plan view of the target surface in a second variant;

16 shows a schematic illustration of a third exemplary embodiment of a semiconductor laser system according to the invention and

Fig. 17 is a plan view of the fiber end face in the third embodiment.

An exemplary embodiment of a power-controlled fractal laser system according to the invention, shown in FIG. 1, comprises a radiation generator system 10, which is followed by an optical fiber system 12, from which a total laser radiation 14 emerges, which in turn hits a target surface 16 of an object to be irradiated with the total laser radiation 14 19 hits. The target area is defined as the area which is illuminated when all the semiconductor laser units are lasered.

The radiation generator system 10 comprises a plurality of half-laser units 18- to 18 _N , each of which generates laser radiation, which is coupled into a light-guiding fiber 20-, 20 _N each. The light-guiding fibers 20 to 20 _N are then combined to form a fiber bundle 22 which is encompassed by the light guide system 12. The fiber bundle 22 forms at one end 24, as shown in FIGS. 1 and 2, an end face 26 in which all the fiber end faces 28 of the fibers 20 to 20 _N forming the fiber bundle 22 lie. The fiber end faces 28 are preferably arranged in the end face 26 such that they are at a distance A from one another, this distance A varying depending on the corresponding embodiment (FIG. 2).

However, the distance A can also, as shown in one variant in FIG. 3, approach zero, so that the fiber end faces 28 touch each other.

Each semiconductor laser unit 18- ^ to 18 _N thus has a fiber end face 28- ^ to 28 _N, and from each of these fiber end faces 28- ^ to 28 _{N the} laser radiation generated by the respective semiconductor laser unit 18- to 18 _N essentially emerges and adds up with the laser radiation of the other semiconductor laser units 18- ^ to 18 _N to the total laser radiation 14th

The total laser radiation 14 impinging on the target surface 16 thus likewise represents a bundle of the individual laser radiation from the individual semiconductor laser units 18 to 18 _N , wherein, as shown in FIG. 4, in the case of a one-to-one image of the end surface 26 ( Fig. 3) onto the target surface 16 of the ^ to 28 _N exiting Laser¬ each radiation from each fiber end face 28- a surface element 30, is illuminated to 30 _N of the Ziel¬ surface 16, and wherein in this case, the surface elements 30, do not overlap up to 30 _N. The target surface is the surface in which all surface elements 30- ^ _{bi N} , corresponding to all fiber end surfaces 30-, k _{is N} , lie.

This means that one of the semiconductor laser units 18 to 18 _N is thus indirectly assigned to each of the surface elements 30 to 30 _N within the target area 16. According to the invention, the laser power in each of the individual surface elements 30 to 30 _N can be predetermined. For this purpose, as shown in FIG. 1, the radiation generator system is provided with a controller 32, by means of which each of the semiconductor laser units 18 to 18 _N can be controlled in terms of their power in a defined manner.

For this purpose, the controller 32 has a multiplicity of outputs 34, to 34 _N , of which control lines 36, to 36 _N each lead to the respective semiconductor laser units 20- to 20 _N.

For this purpose, as shown in FIG. 5, the control comprises a central computer unit 38 with a memory 40 in which the laser power provided for each semiconductor laser unit can be stored, and a power unit 34 which is controlled by the computer unit 38 and which has the 34 ^ to 34 _N outputs for the semiconductor laser units 18-18 to 18 _N and supplies each semiconductor laser unit 18 with a current which corresponds to the power specified for this semiconductor laser unit 18 to 18 _N.

Since each semiconductor laser unit 18- ^ to 18 _{N is} uniquely assigned to one of the fiber end surfaces 28- ^ to 28 _N in the end surface 26, each of the surface elements 30- ^ to 30 _{N of} the target surface 16 is inevitably one of the semiconductor laser units 18- ^ to 18 _N clearly assigned, so that the intensity in the respective surface element 30- ^ to 30 _{N can be} controlled by controlling the semiconductor laser unit 18, to 18 _N. With the control it is thus possible to define the power in each of the surface elements 30 to 30 _{N in a} defined manner within the target area 16 and thus to implement different intensity profiles within the target area 16, as shown in FIGS. 6A to D.

For example, as shown in FIG. 6A, only a surface area 42 having an outer square shape is illuminated within the target area 16, that is to say all the surface elements 30 lying therein are illuminated by driving the corresponding semiconductor laser units 18, while those outside the surface area 42 lying surface elements 30 are not illuminated by switching off the corresponding semiconductor laser units 18. Furthermore, the surface elements 30 are not illuminated with the same intensity within the surface area 42, but there is an intensity gradient between them, as is also schematically noted in FIG. 6A. Such an irradiated surface area 42 is preferably used in material processing, in particular hardening, whereby not only the shape of the surface area 42 but also the power gradient occurring within it is important.

Such a local power profile, which is optimally adapted to the respective material processing, can thus be generated with any simple means via the controller 32, the semiconductor laser units 18 operated thereby working optimally and there being no unnecessary power losses for generating this profile. In a second variant, shown in FIG. 6B, a special shape of two irradiated surface areas 44 and 46 is shown, the surface area 44 representing a larger circle than the area 46 and in each case all the surface elements 30 being illuminated with the same intensity. Such a profile is used, for example, for preheating or post-heating during alloying, preheating, for example, with the area 44 and the actual alloying work taking place with the area 46. It is also possible, for example, to illuminate the surface elements 30 with a higher output within the surface region 46 than the surface elements 30 within the surface region 42. All surface elements 30 outside the surface regions 44 and 46 are not illuminated.

A third exemplary embodiment is shown in FIG. 6C. In this case, an oval surface area 48 is illuminated within the target surface 16, this oval surface area 48 with its long axis 49 running parallel to a direction of movement. Such an oval surface area is preferably used for welding, the longitudinal direction of the weld seam running approximately parallel to the long axis 49 of the oval surface area 48.

Preferably, all surface elements 30 within surface area 48 are irradiated with the same intensity. However, it is also possible to provide an intensity gradient within the oval area. A third variant, shown in FIG. 6D, shows the irradiation of two longitudinally oval surface areas 50 and 52 lying next to one another, all surface elements 30 being illuminated with the same intensity within the surface areas 50 and 52.

Such illumination of two longitudinal oval surface areas lying next to one another is preferably used in the processing of special geometric structures.

In addition to merely locally varying the power within the target area 16, there is also the possibility, as shown in FIG. 7, of providing an area 54 within the target area 16 in which the incident intensity in all area elements 30 is temporally oscillated, while in an area outside the area Surface area 54 lying edge area 56, the intensity in the individual surface elements 30 does not oscillate. For clarification, the two areas 54, 56 are separated by a dashed line.

In the exemplary embodiments described above, in which the fiber end faces 28 are imaged one-to-one onto the surface elements 30 of the target area 16, between the end face 26 and the target area 16, as shown in FIG. 1, an imaging optics 60 is provided, which in the simplest case represents a lens.

In this case, the total laser radiation 14 is formed by the sum of all spherical waves emanating from all fiber end faces 28, which together form a beam result, which in turn is imaged by the imaging optics onto the target surface 16, so that in the simplest case the fiber end surfaces 28 are imaged one-to-one onto the surface elements 30.

If, however, the fiber end faces have a distance A, for example in the region of the thickness of one of the fibers and thus a diameter of a fiber end face 28, adjoining surface elements 30 can be achieved on the target surface 16 in such a way that the mapping does not comply with the requirements of an exact corresponds to the geometric image, but the target area lies outside of an image area created in a geometric image, for example between a focal plane and the image area. However, this reduces the areal density of the incident performance.

If the imaging optics 60 are afflicted with imaging errors so that they do not image a flat end surface 26 into a flat target surface 16, it is provided in a further advantageous variant, shown in FIG. 8, that the end surface 26 'is not as a flat surface Surface but is designed as a curved end surface 26 'corresponding to the imaging errors of the imaging optics 60, so that with this end surface 26' a compensation of the imaging errors of the imaging optics 60 is possible and thus all fiber end faces 28 are imaged on one plane as the target surface 16 or another desired one Surface shape of the target flat 16.

In the simplest case, each of the semiconductor laser units 18 comprises, as shown in FIG. 9, a laser diode 70 with a correspondingly doped laser-active layer 72, which comprises a laser oscillator 71, delimited by phase gratings 81 and 82, and a laser amplifier 73 directly adjoining it and extends in a longitudinal direction 74, and in which a laser radiation 76 which spreads out in the longitudinal direction 74 builds up emerges from one end 78 of the laser-active layer 72, while it is reflected into an opposite end region 80 of the laser-active layer, for example by the phase grating 82.

The laser radiation 76 emerging from the end 78 is reflected by a mirror 83 and is coupled into an end 84 facing the mirror 83 of the fiber 20 assigned to the semiconductor laser unit 18. The mirror 83 is preferably designed as a mirror 83 focusing transversely to the longitudinal direction 74, since the laser radiation 76 diverges transversely to the longitudinal direction towards the end 78 and also occurs in this form from the end 78.

In the simplest case, as shown in FIG. 9, the mirror 83 is an integral element of a substrate 88 which carries the laser diode 70 and into which the mirror 83 is molded with the desired inclination with respect to the end 78.

The laser diode 70 is supplied with power via two feed lines 90 and 92, the feed line 92 being connected to the substrate 88 and the feed line 90 being connected to a contact made on the laser diode 70.

The power of the semiconductor diode 70 can be controlled via a voltage and current characteristic that can be predetermined by the controller 32 at the connections 90 and 92. In a further variant of a semiconductor laser unit 18 according to the invention shown in FIG. 10, the laser diode 70 is constructed in the same way as in the variant shown in FIG. 9.

All elements are therefore provided with the same reference numerals, so that reference can also be made to the description of the above variant with regard to the description thereof.

Only the mirror 83 is designed as a flat mirror and a lens 94 is provided to compensate for the divergence of the laser radiation 76, which couples the laser radiation 76 into the end 84 essentially without loss. The lens 94 is preferably also held on the substrate 88, which also carries the mirror 83.

In a further variant of a semiconductor laser unit according to the invention, shown in FIG. 11, the laser diode 70 is of the same design as in the two variants described above and the same reference numerals are also used. With regard to the description of the individual elements, reference is therefore made in full to the above variants.

In contrast to the above variants, an index lens 100 immediately adjoins the end 78, namely in the longitudinal direction 74, which compensates for the divergence of the laser radiation 76 and an end 102 following the index lens 100 in the longitudinal direction 74 of the latter Coupled fiber 20 associated with semiconductor laser unit 18. According to the invention, in the first exemplary embodiment, shown in FIG. 1, all the semiconductor laser units 18 are constructed such that they deliver laser radiation with essentially the same wavelength that is combined to form the total laser radiation 14.

In contrast to the first exemplary embodiment, provision is made in a second exemplary embodiment, shown in FIG. 12, for two groups of semiconductor laser units 18A- _j ^ _{i N} and lβB- ^ - _{i N to be} provided, the semiconductor laser units lδA. ^ _{LDis N work} on one wavelength and the semiconductor laser units lδB- ^ _{lDi N} on a second, different from the first wavelength.

Fibers 20A then lead from these semiconductor laser units 18A and fibers 20B from the semiconductor lasers 18B, all of which are combined to form the fiber bundle 22. The fibers 20A and 20B are guided in the fiber bundle 22 in such a way that in the end face 26, as shown in FIG. 13, in addition to a fiber end face 28A, assigned to one of the semiconductor laser units with the first wavelength, a fiber end face 28B, assigned to one of the semiconductor laser units with the second wavelength, etc., which means that the fiber end faces 28A and 28B alternate with one another for laser radiation of different wavelengths.

Depending on the choice of the illustration, it is now possible to image the fiber end faces 28A and 28B on the target surface 16 such that a surface element 30A lies next to a surface element 30B in the target surface, as shown in FIG. 14, or it it is possible to choose the image so that the surface elements 30A ' and 30B 'overlap with one another and, as shown in FIG. 15, form a common surface area on the target surface 16, so that in this, as a result of the overlap of both surface elements 30A' and 30B ', either radiation with one or the other or a mixture of both wavelengths is possible.

A third exemplary embodiment of a semiconductor laser system according to the invention, shown in FIG. 16, is constructed in principle in the same way as the two preceding exemplary embodiments, so that the same reference numerals are used for the same parts.

In contrast to the exemplary embodiments described above, however, detector fibers 110 ^ y. ± s _M are additionally provided in the fiber bundle 22, which, as shown in FIGS. 16 and 17, have their fiber end faces 112- ^ in the end face 26 _{JDis M lie} in a regular manner between the fiber end faces 28, so that the fiber end faces 112 are mapped onto the target area in the same way as the fiber end faces 28 are mapped.

Ends 114 1 to M ^c * ^ler Ds ^ ector fibers HO lying opposite the fiber end faces 112- _{to M} end on a detector matrix 116 which for each individual detector ^fiber HO _j to M ^< * ^{iie em} P ^ran 9 ^ene and that by the Fiber end surface 112 received radiation individually detected.

With this detector matrix 116, an image of the target area 16 can thus be acquired, wherein an image of the target area can be displayed on a screen 120 by means of a corresponding image processing device 118. A number of detector fibers 110 ₁ _M is preferably incorporated into the fiber bundle 22 in such a way that a sufficiently precise representation of an image of the irradiated target area on the screen 120 is possible and thus an exact observation of the irradiated area areas 42 of the target area 16.

In addition, the screen provides the possibility of not only detecting the position of the irradiated surface areas 42, but also their relative position with respect to the surface of the workpiece, that is to say with regard to a weld seam to be carried out, so that there is the possibility, in turn, of the controller 32 defining the local one Specify the intensity distribution within the target area even more precisely.

For example, by moving the irradiated surface area 42 within the target surface 16, there is still the possibility of an exact alignment of the surface area 42 relative to the surface of the workpiece or object 19, for example to a weld seam thereon.

Claims

P A T E N T A N S P R Ü C H E

Semiconductor laser system with

a plurality of semiconductor laser units comprising a laser oscillator, from each of which laser radiation emerges, with a light-conducting fiber assigned to each semiconductor laser unit, with a coupling element which couples the laser radiation emerging from the respective semiconductor laser unit into the respective light-conducting fiber, and with one the fibers comprising fiber bundles as a light guide system, which has an end from which emerges a total laser radiation formed by the sum of the coherent laser radiation generated in each case by the semiconductor laser units and which illuminates a target surface on an object to be irradiated when all semiconductor laser units are lasered, characterized in that a controller (32) is provided with which the power of each individual semiconductor laser unit (18) can be controlled in a defined manner, and in that the controller (32) irradiates different surface elements (30) of the target surface e (16) with an individually definable intensity for each surface element (30) can be specified. Semiconductor laser system according to Claim 1, characterized in that the laser radiation (76) emerging from each semiconductor laser unit (18) has a laser radiation field which is independent of the intensity of the laser radiation (76) of the other semiconductor laser units (18).

Semiconductor laser system according to one of the preceding claims, characterized in that the laser radiation (76) emerging from each semiconductor laser unit (18) is decoupled from the laser radiation (76) of the other semiconductor laser units (18) radiation field.

Semiconductor laser system according to one of the preceding claims, characterized in that the laser radiation (76) forming the total laser radiation (14) is decoupled from the radiation field.

Semiconductor laser system according to one of the preceding claims, characterized in that the controller (32) can be given a locally varying radiation profile for the target surface (16).

Semiconductor laser system according to one of the preceding claims, characterized in that the controller (32) can be given a time-varying radiation profile of the target surface (16). 7. Semiconductor laser system according to one of the preceding claims, characterized in that in the region of the end (24) of the light guide system (12) fiber end surfaces (28) of the fibers (20) from which the laser radiation of the associated semiconductor laser units (18) emerge , lie in an end surface (26) of the light guide system (12) that can be optically mapped onto the target surface (16).

8. A semiconductor laser system according to claim 7, characterized in that an intermediate space (a) between the fiber end faces (28) is less than three times the fiber thickness.

9. A semiconductor laser system according to claim 8, characterized in that the fiber end faces (28) in the end face (26) lie side by side.

10. A semiconductor laser system according to one of claims 7 to 9, characterized in that the shape of the end surface (26) is adapted to a shape of the surface of the object to be irradiated (29) in the region of the target surface (16).

11. A semiconductor laser system according to one of the preceding claims, characterized in that the laser radiation of different semiconductor laser units (18) at least partially strikes different surface elements (30) of the target surface (16). 12. Semiconductor laser system according to one of the preceding claims, characterized in that the laser ^v radiation from different semiconductor laser units (18) strikes different surface elements (30) of the target surface (16).

13. A semiconductor laser system according to one of claims 1 to 11, characterized in that the laser radiation of each semiconductor laser unit (18) is partially superimposed on the target surface (16) with the laser radiation of other semiconductor laser units (18).

14. Semiconductor laser system according to one of the preceding claims, characterized in that an imaging optics (60) is provided between the end (24) of the light guide system (12) and the target surface (16).

15. A semiconductor laser system according to one of the preceding claims, characterized in that a shape of the end face (26 ') is adapted to the optical imaging properties of the imaging optics (60).

16. Semiconductor laser system according to one of the preceding claims, characterized in that each semiconductor laser unit (18) comprises a single laser-active diode strip.

17. A semiconductor laser system according to one of claims 1 to 15, characterized in that each semiconductor laser unit (18) comprises a plurality of laser-active diode strips. 18. Semiconductor laser system according to one of the preceding claims, characterized in that each semiconductor laser unit (18) comprises a laser oscillator (71) and a laser amplifier (73).

19. Semiconductor laser system according to one of the preceding claims, characterized in that all semiconductor laser units are designed for the same wavelength.

20. A semiconductor laser system according to one of claims 1 to 18, characterized in that different semiconductor laser units are formed for different wavelengths.

21. A semiconductor laser system according to claim 20, characterized in that the semiconductor laser units comprise a group of semiconductor laser units (18A, 18B) with the same wavelength.

22. A semiconductor laser system according to claim 21, characterized in that the semiconductor laser units (18) comprise a plurality of groups of semiconductor laser units (18A, 18B), each having the same wavelength within the same.

23. A semiconductor laser system according to any one of claims 20 to 22, characterized in that the fiber end faces of fibers emitting laser radiation of different wavelengths are combined to form a radiation group, and that the radiation groups are arranged side by side in the end surface. 24. Semiconductor laser system according to one of the preceding claims, characterized in that as a coupling element for coupling the fiber (20) to the semiconductor laser unit (18) a imaging element (83, 94) carried by the substrate (88) of the semiconductor laser unit (18) ) is provided.

25. A semiconductor laser system according to claim 24, characterized in that the imaging element (83, 94) focuses the laser radiation (76) widening in the direction parallel to the layer planes (72) of the semiconductor laser unit (18) onto the fibers (20).

26. Semiconductor laser system according to one of the preceding claims, characterized in that the fiber bundle (22) comprises detector fibers (110).

27. A semiconductor laser system according to claim 26, characterized in that one end (112) of the detector fibers (110) at the end (24) of the light guide system (12).

28. A semiconductor laser system according to claim 27, characterized in that the end (112) in the end face (26) is adjacent to the fiber end faces (28).

29. A semiconductor laser system according to claim 27 or 28, characterized in that the ends (112) of the detector fibers (110) on the target surface (16) are mapped. 30. Semiconductor laser system according to one of claims 26 to 29, characterized in that an optical detector (116) for observing the target surface (16) is arranged at another end (114) of the detector fibers (110).

31. A semiconductor laser system according to claim 28, characterized in that the optical detector is a matrix detector for observing the target area.