WO2013068289A1 - Beam switch and laser processing device therewith - Google Patents

Abstract

The invention relates to a beam switch (1), comprising: a first optical input (3) for coupling in a first laser beam, a second optical input (4) for coupling in a second laser beam, a switching device with a switching element (5) that is movable between a first position, in which a first light path (LW1) from the first optical input (3) to an optical output (8) is released, and a second position, in which a second light path from the second optical input (4) to the optical output (8) is released. The beam switch (1) is characterised by a closure element (10), preferably movement-coupled to the switching element (5), for light-tight closure of the second optical input (4) in the first position of the switching element, and for light-tight closure of the first optical input (3) in the second position of the switching element, and/or in that the switching element is arranged in a housing (2) that is closed off at the optical inputs (3, 4) and at the optical output (8) with a respective optical element (14a, 14b, 15) that is transmissive for laser radiation. The invention also relates to a laser processing system with such a beam switch (1).

Description

 Beam switch and laser processing system with it

The present invention relates to a beam splitter, comprising: a first optical input for coupling a first laser beam, a second optical input for coupling a second laser beam, a switching device with a switching element which is movable between a first position, in which a first light path from the first optical input is enabled to an optical output, and a second position in which a second light path from the second optical input to the optical output is enabled. US 2009/0283506 A1 discloses a laser processing machine with a beam switch for switching different laser beams to a common optical output. By means of a movable device two pairs of mirrors are displaced so that one laser beam is directed to a measuring device, while the other laser beam is directed to the laser output to the optical output. Depending on the particular wavelength of the laser beam currently being used for laser processing, a lens with a suitable magnification is selected.

From US 5,166,493 a device for laser drilling in a two-stage process has become known, in which laser light with different wavelength is used. For switching the laser or the laser beams to a common optical output, a hinged deflection mirror is provided. If required, different focusing lenses can be positioned in the beam path.

OBJECT OF THE INVENTION It is an object of the present invention to further develop a beam switch of the type mentioned at the beginning in such a way that a selection of laser light from two light sources without any retroactive effect on the respectively inactive light source is made possible. Another object is to reduce the maintenance of the aforementioned beam switch. Subject of the invention

The object is achieved by a beam splitter of the type mentioned, in which a preferably coupled to the switching element closure element for light-tight sealing of the second optical input in the first position of the switching element and the light-tight sealing of the first optical input in the second position of the switching element is.

The beam splitter according to the invention makes it possible to switch over between two or more light paths or to enable a respective optical input and thus to choose between two or more optical inputs. The laser beam of each unlocked optical input is directed to an optical output. In a subsequent to the optical output Assembly can be done, for example, a Sirahlformung.

According to one aspect of the invention, that optical input which is currently inactive is sealed in a light-tight manner with the closure element, so that no scattered radiation or no back-reflected radiation can escape from the beam switch through the optical input, and e.g. is undesirably coupled by a light guide cable connected to the optical input in a just inactive light source.

Preferably, there is a movement coupling of the closure element with the switching element, so that the optical input of the respective inactive beam path is automatically closed by actuation of the switching element. There is therefore no need for additional control for the closure element. Thus, the leakage of stray radiation from the beam switch can be avoided without the need for additional control effort. The use of a closure element also allows a reduction of the radiation protection arrangements outside the beam splitter.

The movement coupling can be realized by the closure element mechanically fastened to the switching element and movable with it, e.g. is displaceable. The closure member may be in the form of, for example, a plate-shaped slider (e.g., in the form of a metallic sheet) which is pushed by the switching member in front of the corresponding optical input to close the opening thereof.

In a preferred embodiment of the beam switch according to the invention, the switching element is designed as a linearly displaceable carriage and the closure element is attached to the carriage. The carriage can be moved back and forth between the two optical inputs. It may optionally be provided other than linear movements of the carriage, a linear movement is particularly easy to implement.

As an alternative to the embodiment as a slide, the switching element may for example also be configured as a (rotatable) folding mirror, which serves as deflection element for deflecting at least one of the laser beams and which is switchable between two angular positions in order to release a respective light path. Of the Folding mirror is not motion-coupled with the closure element as a rule, but it is provided a separate drive means which, for example, the plate-shaped closure element reciprocates in a typically linear movement between the two positions for closing the optical inputs.

In one embodiment, the switching device as an actuator for moving the carriage comprises a pneumatic cylinder (with piston), via which the movement of the carriage can be controlled. In order to achieve a particularly tolerance-insensitive switching movement in the direction of movement, fixed stops for the carriage are preferably provided, against which the carriage rests in the first or in the second position.

To enable the light paths, the switching device preferably comprises deflection means for deflecting the laser beams within the beam switch, in particular at least one deflection mirror. By rotating or shifting the mirrors or possibly by using semitransparent mirrors, the laser beams can be guided within the beam splitter along a desired light path.

In a preferred embodiment, at least one deflecting means is attached to the switching element, in particular to the carriage. The one or more deflection means are suitably positioned on the switching element relative to the closure element, so that in one position releases a light path and the other light path is blocked by the closure element. Preferably, during the movement of the carriage, the relative position of the deflection means does not change to the closure element. The closing of the inactive beam path and the positioning of the deflection means can in this case by a simple displacement of the switching element, e.g. in the form of a carriage.

In a preferred embodiment, in each case a connection for connecting a light-conducting cable (LLK) is provided at the first optical input and / or at the second optical input. Such a light guide cable serves to guide laser radiation, typically at a predetermined wavelength. Such a light guide cable comprises at least one end-mounted connector, which with a corresponding connection, for example in the form of a plug receptacle, can be connected to the beam switch. By providing LLK connections at the two optical inputs, the coupling of laser radiation into the beam splitter can take place in a particularly simple manner. The optical inputs can be formed, for example, as tubular beam guides. The two laser beams can be coupled in parallel in the beam switch in this case, which, for example, when using a transversely displaceable to the optical inputs switching element, for example in the form of the carriage described above, a compact design of the beam switch allows.

The connections for the light guide cables are preferably aligned parallel to one another, so that the connected light guide cables run parallel to one another in the region of the coupling. For collimation of the laser beams, an optical element (collimation lens), serve, which is attached to the beam splitter itself. Optionally, however, a collimating optical element (for example, a collimating lens) can also be integrated into a respective light guide cable so that a co-stimulated laser beam emerges from the light guide cable. In both cases, the (collimated) laser beams which strike the switching element in the beam path are parallel to each other.

Another aspect of the invention relates to a beam switch of the type mentioned above or as described above, in which the switching element is arranged in a housing which is closed at the optical inputs and the optical output in each case with an optical element permeable to laser radiation. In this way, the risk of contamination in the use of the beam splitter can be significantly reduced, wherein the closing of the housing is not necessarily hermetic, i. must be substantially airtight. For example, when changing the light guide cable, the risk of contamination at the entrances can be reduced by an air purge from the inside to the outside. For this purpose, a compressed air source can be arranged inside the housing, e.g. is activated only during the change of the light guide cable. Optionally, the risk of contamination can also be reduced by pivoting the entire beam shaping in the horizontal.

In the simplest case, the optical elements are transparent components for the radiation of the particular laser wavelength used, for example of quartz glass, which do not serve for beam forming (eg plane plates). It understands itself, that the developments of the beam switch described above in connection with the first aspect of the invention, for example the use of a carriage as a switching element, can be combined with the second aspect, without the first aspect of the invention (with respect to the closure element) compelling must be realized.

In a preferred embodiment, the optical elements at the optical inputs are collimating lenses to collimate the laser radiation divergently exiting the optical fibers. The deflection of the laser beams within the beam splitter takes place in the collimated beam path. The deflection in the collimated beam path is particularly advantageous, since this allows the use of lenses of the same focal length in both inputs, although the light paths for both inputs within the switch are clearly different. The collimating lenses are preferably adjustable in all three spatial directions (x-, y- and z-direction) in order to obtain the most identical (collinear) beam path of the two laser beams at the optical output or after the beam splitter. By means of an adjustment of the Kollimationslinsen in the z-direction at the respective optical input of the respective distance of the lens with respect to the fiber end of the optical fiber can be accurately adjusted and thus each compensated component tolerances a collimated beam generated. In order to focus the outgoing laser beam in front of a subsequent assembly (e.g., a variable collimator), it is advantageous if the optical element at the optical output of the beam switch is a focusing lens. In particular, an adjustable collimator, e.g. in the form of a telescopic arrangement, serve, which allows adjustment of the focus size of the beam emerging from the beam laser beam before the final focusing on a workpiece.

The invention also relates to a laser processing system with a beam splitter described above. In this case, the beam splitter can be connected via two or more optical fiber cables to corresponding laser sources which serve to supply laser light with identical or optionally different wavelengths to a common laser processing head. The beam switch allows fast program-controlled, process-reliable switching between two or more light paths. This will provide a more flexible use of laser sources allows beam guidance by means of optical cables allow. The laser sources may be, for example, solid-state lasers.

Further advantages of the invention will become apparent from the description and the drawings. Likewise, the features mentioned above and those listed further below can be used individually or in combination in any combination. The embodiments shown and described are not to be understood as exhaustive enumeration, but rather have exemplary character for the description of the invention.

1 shows a three-dimensional sectional representation of a beam switch with a

 unlocked first beam path;

FIG. 2 is a three-dimensional sectional view of the beam switch of FIG. 1 with an enabled second beam path; FIG.

Fig. 3 is a schematic representation of mirrors and lenses in one

 Beam switch;

Fig. 4 shows a detail of a laser processing system with a

 Laser processing head and with a beam switch.

A beam switch 1 shown in FIGS. 1 and 2 comprises a housing 2 with a first optical input 3 and a second optical input 4, which in the present example are designed as tubular beam guiding channels and at which laser beams are coupled in via optical fiber cables (not shown) , The optical inputs 3, 4 or the beam guide channels run in the present example in parallel to couple two laser beams aligned parallel to one another into the beam splitter 1. The beam switch 1 comprises a switching device with a movable carriage 5, on which two deflecting mirrors 6, 7 are mounted. The carriage 5 is movable between a first position (FIG. 1) and a second position (FIG. 2) and serves as a switching element for the beam splitter 1. In the first position shown in FIG. 1, the carriage 5 is located at a right end stop and the laser beam entering through the first optical input 3 is deflected twice by 90 ° via the mirror pair 6, 7 and enters the first optical input parallel to the beam entry direction 3 through an optical output 8 of the beam switch 1, which is also designed as a tubular beam guiding channel. In the first position of the carriage 5, a first light path LW1 is thus enabled, ie, no components are arranged in the first position of the carriage 5 between the first input 3 and the output 8, which block the first light path LW1. In the second position, shown in FIG. 2, the carriage 5 is located at a left end stop and the laser beam entering through the second optical input 4 can pass unhindered through the optical output 8, ie a second light path LW2 is released. By activating one of the light paths LW1, LW2, either one of the laser beams can optionally be provided on a subsequent assembly (not shown in FIGS. 1 and 2), for example a beam shaping unit. By the beam splitter 1 thus switching the light paths LW1, LW2 or the activation of each one of the optical inputs 3, 4 and thus the selection between two laser beams allows, which typically come from different light sources and of these two with the inputs. 3 , 4 connected light guide the beam switch 1 are supplied.

On the carriage 5, a closure element 10 in the form of a closure slide (plate-shaped plate) is mounted and positioned so that it closes the first optical input 3 in a light-tight manner in the first position of the carriage 5, the second optical input 4 and in the second position of the carriage 5. The closure element 10 is arranged for this purpose at a small distance from the outlet opening of a respective optical input 3, 4, typically at a distance of less than 1 mm. The beam splitter 1 according to the invention thus forcibly ensures that a respective opening of the optical input 3, 4 of the currently unused light path LW1, LW2 is covered or closed.

In this way, the corresponding optical input 3, 4 is protected from stray radiation or back reflections, which from the other, the active light path LW1, LW2 originate. By the joint arrangement of the deflection elements (here: pair of mirrors 6, 7) and the closure element 10 on the carriage 5, a motion coupling is realized, so that both the activation of one of the light paths LW1, LW2 and the closing of the non-active (not unlocked) optical Input 3, 4 is made possible solely by the movement of the carriage 5. To activate a light path LW1, LW2 and to close the respective other light path LW2, LW1 therefore only a single (electronic) control is necessary.

In the present example, the movement of the carriage 5 is realized by a pneumatic cylinder 9 with a piston (not shown) which is connected to the carriage 5 via a flexible coupling and which can be actuated via a control valve (not shown) which is part of the control device is. To protect against outgassing, the piston rod and the coupling can be covered with a bellows (see Fig. 1 and 2), whose inner air volume with the space outside the beam splitter 1 has connection. In this way, a pressure equalization of a change in the volume of air generated in the housing 2 during the movement of the carriage 5 can take place. The piston of the pneumatic cylinder 9 is extended in the first position (right stop, see Fig. 1) and retracted in the second position (left stop, see Fig. 2). The pneumatic cylinder 9 is also part of the control device and serves as an actuator for linear displacement of the carriage 5 along a provided in the housing 2 (not shown) linear guide.

On the peripheral surface of the Pneumatikzyiinder 9 a pair of sensors 11 is arranged, which is used for the switching of the control valve of the cylinder, ie, the sensor pair 11 is driven by the position of the piston rod. When the respective end position of the piston rod is reached (extended or retracted), the pneumatic valve is switched. A respective sensor of the sensor pair 1 1 can be actuated inductively, for example, by the bottom of the piston rod upon reaching the respective end position. The (not shown) Lichtleitkabel be connected to the beam splitter 1 to a respective terminal 19, which is formed in the present example as a plug connection and for latching connection with a (not shown) connector plug of a respective optical cable. At the two optical inputs 3, 4 contact rings 13 are provided, which can be contacted by means of an external (not shown), so that depending on the position of the piston of the pneumatic cylinder 9, the (not shown) laser sources are switched on or off. The housing 2 is closed at the optical inputs 3, 4 and at the optical output 8 by means of optical elements. Collimating lenses 14a, 14b are used as optical elements at the optical inputs 3, 4 in the present example. An adjusting device not described in more detail here makes it possible to displace the collimating lenses 14a, 14b in the x and y directions (perpendicular to the beam direction), around the two parallel but divergent laser beams entering the beam splitter 1 through the optical inputs 3, 4 after the switch to coincide (concentricity). By an adjusting device for the Kollimationslinsen 14a, 14b in the z-direction (beam direction), it is also possible to bring the focus position in the intermediate focus to cover. For this purpose, the sockets of the collimating lenses 14a, 14b can be moved in the z-direction, while the position of the optical fibers and the focusing lens 15 remain stationary. An axial movement of the collimating lenses 14a, 14b can take place until a sharp image of an alignment laser beam is made (possibly with the aid of adjustment aids). The use of collimating lenses 14a, 14b at the optical inputs 3, 4 enables beam guidance within the beam splitter in the collimated state. At the optical output, a focusing lens 15 is used as an optical element to focus the laser beams to a common intermediate focus. The focal lengths or the imaging ratios of the collimating lenses 14a, 14b and the focusing lens 15 are selectable as required, but preferably the focal lengths of the three lenses 14a, 14b, 15 are identical.

In the embodiment of the beam splitter 1 shown in Fig. 1 and in Fig. 2, the switching between the two light paths LW1, LW2 by means of two parallel aligned 90 ° -Umlenkspiegel 6, 7 realized, which are mounted on the carriage 5 and movable therewith , It is understood that other concepts for switching between multiple laser beams can be used. For example, in Fig. 3, a beam splitter 1 for switching laser beams from three different optical cables LLK1, LLK2, LLK3 shown, wherein the laser beams from the first and second optical fiber LLK1, LLK2 parallel to each other and the laser beam from the third optical fiber LLK3 perpendicular thereto in the Beam splitter 1 are irradiated. Upon entering the beam splitter 1, the laser beams are collimated by collimating lenses 14a, 14b, 14c and directed to the optical output 8 by means of mirrors 16a, 16b. The two mirrors 16a, 16b are moved out of the respective beam path or displaced, so that switching between different beam paths can be realized. In the position of the mirrors 16a, 16b shown in FIG. 3, the laser beam from the second optical fiber cable LLK2 is directed onto the optical output 8, while the other optical paths (also shown in FIG. 3) are inactive.

By moving the first, upper mirror 16a out of the beam path of the first optical cable LLK1 (for example, toward the third optical cable LLK3), the laser beam from the first optical fiber cable LLK1 is directed onto the optical output 8. The first mirror 16a thus serves as a switching element between the optical inputs of the first and second optical fiber cable LLK1, LLK2. By switching or shifting the second, lower mirror 16b out of the beam path of the third optical cable LLK3, the laser beam is deflected out of the third optical fiber cable LLK 3 to the optical output 8. The second mirror 16b thus serves as a switching element between the optical inputs of the second and third optical cable LLK2, LLK3. The respective laser beam exiting from the optical output 8 is focused by the focusing lens 15 in an intermediate focus 18 and, for further beam shaping, to a subsequent assembly, e.g. passed through a (variable) collimator device. The beam splitter 1 or the region in which the collimated beam path runs is separated from the environment by the optical elements 14a, 14b, 14c, 5. It is understood that instead of the deflection or switching between the light paths in the collimated beam path, a switchover in the divergent beam path emanating from the light guide cables LLK1, LLK2, LLK3 can take place.

FIG. 4 shows a section of a laser processing system 17 with a beam switch 1 corresponding to FIGS. 1 and 2, in which divergent laser radiation from two optical cables LLK1, LLK2 is fed to a laser processing head 19. In the a respective switching state of the beam splitter 1 at the optical output 8 emerging laser beams extend along a common optical axis, so that both laser beams are provided at the same location and at a common intermediate focus 18 of the subsequent optical assembly. It is understood that the laser processing system 17 can also be equipped with another beam splitter 1, for example with the beam splitter 1 shown in FIG. 3. 3, at least one closure element may be provided which closes the respectively inactive light paths at the corresponding optical input in a light-tight manner. The closure element may, for example, be a displaceable plate.

Claims

claims 1 . Beam switch (1), comprising:  a first optical input (3) for coupling a first laser beam, a second optical input (4) for coupling a second laser beam, a switching device with a switching element (5) which is movable between a first position in which a first light path (LW1 ) is enabled from the first optical input (3) to an optical output (8), and a second position in which a second optical path (LW2) is enabled from the second optical input (4) to the optical output (8), characterized by preferably with the switching element (5) motion-coupled  A closure element (0) for sealing the second optical input (4) in the first position in a light-tight manner and for sealing the first optical input (3) in the second position in a light-tight manner. 2. beam switch according to claim 1, characterized  in that the switching element is designed as a linearly displaceable carriage (5), and in that the closure element (10) is attached to the carriage (5). 3. beam switch according to claim 2, characterized  the switching device comprises, as an actuator for moving the carriage (5), a pneumatic cylinder (9). 4. beam switch according to one of the preceding claims, characterized  in  that the switching device deflecting means, in particular at least one Deflection mirror (6, 7, 16a, 16b) includes. 5. beam switch according to claim 4, characterized in that  in that at least one of the deflecting means (6, 7, 16a, 16b) is attached to the switching element. 6. beam switch according to one of the preceding claims, characterized  in  in that a respective connection (19) for connection to a light-conducting cable (LLK, LLK2) is provided on the first optical input (3) and / or on the second optical input (4). 7. beam switch according to claim 6, characterized  the two connections (19) for the lightguide cables (LLK1, LLK2) are aligned parallel to one another. 8. beam switch according to the preamble of claim 1, in particular according to one of the preceding claims,  characterized,  the switching element is arranged in a housing (2) which is closed at the optical inputs (3, 4) and at the optical output (8) in each case with an optical element (14a, 14b, 15) permeable to laser radiation 9. beam switch according to claim 8, characterized  that the optical elements at the optical inputs (3, 4)  Collimating lenses (14a, 14b) are. 0. beam switch according to one of claims 8 or 9, characterized in that the optical element at the optical output (8) is a focusing lens (15). 1 1. Laser processing system (17) with a beam switch (1) according to one of  previous claims.