Device and method for machining a workpiece by means of at least two laser beams

Abstract

The invention relates to a device (10) having the features of claim 1 for machining a workpiece (12) by means of at least two laser beams (16, 20) and to a method having the features of the additional independent claim for machining a workpiece (12) by means of at least two laser beams (16, 20).

Description

[0001] Title: Device and method for processing a

[0002] workpiece using at least two laser beams

[0003] Description

[0004] The invention relates to a device for machining a workpiece by means of at least two laser beams with features of claim 1 and to a method for machining a workpiece by means of at least two laser beams with features of the independent claim.

[0005] For a variety of laser material processing applications, short laser pulses with high laser pulse repetition rates are required in order to achieve, for example, high area processing rates. In addition to the temporal precision of the pulse emission, the achievable speed of the spatial deflection is often technically limiting. In addition, the implementation of the required processing speeds

[0006] Laser intensity is generally technically difficult. It is therefore an object of the present invention to provide a device and a method for machining a workpiece using at least two laser beams, while eliminating the above-mentioned disadvantages.

[0007] The above object is achieved by a device for machining a workpiece by means of at least two laser beams having the features of claim 1.

[0008] The device comprises a first laser device for generating a first laser beam having a first wavelength and a second laser device for generating a second laser beam having a second wavelength different from the first wavelength.

[0009] The device comprises a superposition device for generating a superimposed laser beam by superimposing, in particular coherently, the first and second laser beams. The superposition device can comprise a lens for coupling the first and second laser beams (e.g., into a fiber) or can be designed as such a lens. The superposition unit can be designed as a single-mode fiber combiner.

[0010] The device comprises an amplifier device for amplifying the superimposed laser beam and a separating device for separating the superimposed laser beam into the first and second laser beams. The superimposed laser beam can have a spectral bandwidth that lies within a spectral bandwidth of the amplifier device. The separating device can be arranged downstream of the amplifier device. The separating device can be configured to introduce angular dispersion of the first and second laser beams.

[0011] The device also comprises a focusing device for focusing the first laser beam onto a first position on the workpiece and for focusing the second laser beam onto a second position on the workpiece that is different from the first position. In particular, the first position is arranged at a distance from the second position on the workpiece. In the present case, the distance between the first position and the second position means a distance between a first center point of the first laser beam focused on the workpiece and a center point of the second laser beam focused on the workpiece along a surface of the workpiece. It is conceivable that the laser spots generated on the workpiece by the two laser beams can overlap.

[0012] The focusing device may have a focal length of 600 mm (millimeters). The first and / or the second

[0013] Wavelengths can each lie in a spectral band from -70 nm to +70 nm around 1030 nm.

[0014] This allows for simple amplification of the first and second laser beams. This allows for optimal machining of the workpiece.

[0015] According to a further development of the device, the amplifier device can comprise a rod amplifier, a fiber, a slab amplifier, and / or a disk amplifier. The individual amplifiers mentioned above, if present, can be arranged one after the other in the order mentioned above. Of course, a different order of the amplifiers mentioned above, if present, is also conceivable. It is also conceivable that the amplifier device can also comprise a different amplifier.

[0016] The amplifier device can comprise an active medium (e.g. Yb:glass, Yb:LuAG (ytterbium-doped lutetium-aluminum garnet), Yb:YAG (ytterbium-doped yttrium-aluminum garnet) or Yb-doped fused silica). The active medium can comprise laser-active ions (e.g. Yb3+). The active medium can be Yb-doped. The active medium can be arranged within an amplifier, e.g. a fiber.

[0017] The device may include a Mamyshev regenerator for shortening pulses. The Mamyshev regenerator may be arranged upstream of the amplifier device.

[0018] In the present case, terms such as "before" an element or "after" an element refer to a propagation direction of the first laser beam, the second laser beam and / or the superimposed laser beam.

[0019] This allows the amplifier device to be implemented using simple means and the superimposed laser beam to be amplified.

[0020] According to a further development of the device, the separation device can comprise at least one dispersive element. The dispersive element can be designed as an optical grating and / or as a prism. This allows the separation device to be relocated using simple means, and the superimposed laser beam can be separated again into the first and second laser beams.

[0021] According to a further development of the device, the separation device can comprise at least two dispersive elements. The at least two dispersive elements can be configured such that a distance between the first and second laser beams can be adjusted by varying a distance and / or an orientation of the at least two dispersive elements relative to one another.

[0022] The two dispersive elements can be mounted for rotation. This allows, for example, the angle between the two dispersive elements to be adjusted about an axis perpendicular to the propagation or dispersion plane. A distance between the first position of the first laser beam and the second position of the second laser beam on the workpiece can thus be adjusted, for example, by rotating the first and / or second dispersive element.

[0023] This allows the distance between the first and second laser beam to be adjusted or varied using simple means.

[0024] According to a further development of the device, the separating device can be configured such that, after separation, the first and second laser beams are separated by an angular distance that lies in a range from 1 prad (microradian) to 1 mrad (milliradian). This allows the first and second laser beams to be optimally further processed, in particular focused on the workpiece.

[0025] According to a development of the device, the first and the second laser device can each comprise at least one pulsed laser. The pulsed laser can have a pulse duration in a range from 100 fs (femtosecond) to 1 ps (microsecond), in particular in a range from at least 40 ps (picosecond) to a maximum of 1 ns (nanosecond). The pulsed laser can have a pulse repetition rate of 200 MHz (megahertz) to 800 MHz. Alternatively, the first and the second laser device can each comprise at least one CW (continuous wave) laser. A laser diode, in particular a gain-switch diode, preferably a DFB (distributed feedback) diode, can be implemented as the laser source.

[0026] The apparatus can comprise at least one third laser device for generating a third laser beam with a third wavelength. The third wavelength can be different from the first and / or the second wavelength. The third laser device can comprise at least one pulsed laser (in particular with pulses in a range from 1 ns (nanosecond) to 1 ms (microsecond)) or at least one CW laser (or a long-pulsed laser diode). The third wavelength can lie at the edge of an amplifier bandwidth of the amplifier device. The third laser beam can be used to compensate for or adapt the inversion in the amplifier device.

[0027] The device can comprise a fourth laser device for generating a fourth laser beam with a fourth wavelength. The first, second, and fourth laser beams can each be generated by means of a pulsed laser. The first, second, and fourth wavelengths can be spaced apart from a central wavelength of 1 nm (nanometer). The first wavelength can be 1029 nm, the second wavelength can be 1030 nm, and the fourth wavelength can be 1031 nm. A spectral width of the first, second, and fourth laser devices (or their respective pulsed lasers) can be less than 0.1 nm. In this case (analogous to two laser beams), three laser beams are superimposed to form one superimposed laser beam, amplified, and then separated again into three individual laser beams. Of course, the number of laser beams that are superimposed, amplified, and separated again can also be higher, i.e., four or more.The number of laser beams that are superimposed, amplified and separated again can be limited, for example, by the bandwidth of the amplifier device or the active medium.

[0028] This allows the individual laser beams to be generated as flexibly as possible, thus enabling the processing of the workpiece to be carried out as flexibly as possible.

[0029] According to a further development of the device, a ratio of a spectral width of each of the first wavelength and the second wavelength to a spectral distance between the first wavelength and the second wavelength can be 1:5, in particular 1:10, preferably 1:20.

[0030] This allows the first and second laser beams to be optimally superimposed and separated. Furthermore, the ellipticity at the focus can be minimized by the dispersion of the separation device or dispersive element.

[0031] According to a further development of the device, the first laser device can each comprise at least two pulse lasers. The at least two, in particular all, pulse lasers can each be configured to generate a partial beam with the same wavelength. At least two, in particular all, partial beams can be designed with a pulse shift. In particular, the shift can amount to more than one pulse duration. At least two, in particular all, partial beams can form the first laser beam.

[0032] Alternatively or additionally, the second laser device can each comprise at least two pulsed lasers. The at least two, in particular all, pulsed lasers can each be configured to generate a partial beam with the same wavelength. At least two, in particular all, partial beams can be pulse-shifted. At least two, in particular all, partial beams can form the second laser beam.

[0033] This allows the first or second laser beam to be implemented with a very high pulse repetition rate using simple means.

[0034] According to a development of the device, the first and / or the second laser device can comprise a tempering device for varying a temperature of the first and / or the second laser device. The first and / or the second laser device can each be set up in such a way that the first wavelength and / or the second wavelength (or their respective central wavelength) can be shifted or varied. The shift or the variation can be in a range from 0.01 nm / K to 0.5 nm / K, in particular 0.06 nm / K (nanometers per Kelvin). The temperature of the tempering device can be controlled, for example, by means of a T-control.

[0035] In this way, the temperature of the first and / or the second laser device can be varied or adjusted using simple means. The wavelength of the first or the second laser device in particular can be changed or adjusted using the temperature. This can be achieved in particular with diode lasers, in which the junction temperature of the pn junction determines the central wavelength of the amplification, or with DFB (Distributed Feedback) diodes, in which the spacing of the internal grating structure is changed. By adjusting the wavelengths, the dispersion in the separation device can be adjusted and thus the distance between the first laser beam and the second laser beam can be adjusted.

[0036] According to a further development of the device, the device can comprise a scanner optics system for moving the first and / or second laser beam on the workpiece. The scanner optics system can be arranged in front of the focusing device.

[0037] This allows for simple means of implementing a movement of the first or second laser beam on the workpiece. According to a further development of the device, the scanner optics can comprise a galvo scanner and / or a polygon scanner.

[0038] This allows the scanner optics to be implemented using simple means.

[0039] According to a development of the device, the device can comprise a converter device for converting the first and / or the second wavelength. The wavelength can be halved or divided by a third or the frequency belonging to the respective wavelength can be doubled or tripled. The converter device can comprise a non-linear crystal. The converter device can be designed to filter out the third laser beam, in particular by means of the non-linear crystal. The converter device can be arranged downstream of or upstream of the separating device. The converter device can be arranged upstream of the scanner optics.

[0040] This allows the desired wavelength to be achieved using simple means.

[0041] According to a further development of the device, the device can comprise at least one control device for controlling the first laser device, the second laser device, the third laser device, the separating device, the tempering device and / or the scanner optics.

[0042] This allows a control of the device or the individual elements to be implemented using simple means. According to a further development of the device, the

[0043] The focusing device may be configured such that a distance between the first position and the second position is in a range from 0.5 gm (micrometers) to 5 mm, in particular 1 gm to 100 gm.

[0044] This allows the machining of the workpiece to be carried out as optimally as possible.

[0045] The above object is achieved by a method for machining a workpiece using at least two laser beams having the features of the independent claim. The method comprises the following steps:

[0046] Generating a first laser beam having a first wavelength by means of a first laser device.

[0047] Generating a second laser beam having a second wavelength different from the first wavelength by means of a second laser device.

[0048] Generating a superimposed laser beam by superimposing, in particular coherently, the first and second laser beams.

[0049] Amplifying the superimposed laser beam.

[0050] Separating the superimposed laser beam into the first and second laser beams.

[0051] Focusing the first laser beam onto a first position on the workpiece and focusing the second laser beam onto a second position on the workpiece that is different from the first position.

[0052] This allows for simple amplification of the first and second laser beams. This allows for optimal machining of the workpiece.

[0053] According to a further development of the method, the method may comprise the step:

[0054] Changing a distance, in particular a spatial distance, between the first and the second laser beam.

[0055] This allows the machining of the workpiece to be adjusted as desired and optimally.

[0056] According to a further development of the method, the method may comprise the step:

[0057] Generating the first and / or the second laser beam from at least two pulsed partial beams, wherein at least two, in particular all, partial beams have the same wavelength and are designed with a pulse shift relative to one another.

[0058] This allows the first or second laser beam to be implemented with a very high pulse repetition rate using simple means.

[0059] According to a further development of the method, the method may comprise the step of: varying a temperature of the first and / or the second laser device.

[0060] This allows the first wavelength or the second wavelength (particularly in the case of temperature-sensitive laser devices) to be set as required using simple means.

[0061] According to a further development of the method, the method may comprise the step:

[0062] Moving the first and / or second laser beam on the workpiece.

[0063] This allows the workpiece to be processed as desired using simple means.

[0064] According to a further development of the method, the method may comprise the step:

[0065] Converting the first and / or second wavelength .

[0066] This allows a desired wavelength to be set for machining the workpiece using simple means.

[0067] According to a further development of the method, a device according to the above statements can be used to carry out the method.

[0068] With regard to the advantages that can be achieved, reference is made to the relevant explanations of the device. The measures described in connection with the device and / or those explained below can be used to further refine the method.

[0069] Further features, details and advantages of the invention will become apparent from the wording of the claims and from the following description of an embodiment with reference to the drawing. It shows:

[0070] Fig. 1 is a schematic representation of a device for machining a workpiece by means of at least two laser beams.

[0071] The device bears the reference numeral 10 in Figure 1. The device 10 is designed to machine a workpiece 12 using at least two laser beams 16, 20.

[0072] The device 10 comprises a first laser device 14 for generating a first laser beam 16 with a first wavelength and a second laser device 18 for generating a second laser beam 20 with a second wavelength different from the first wavelength.

[0073] The device 10 comprises a superposition device 22 for generating a superimposed laser beam 24 by superimposing the first and second laser beams 16, 20. The device 10 also comprises a separating device 28 for separating the superimposed laser beam 24 into the first and second laser beams 16, 20.

[0074] The device 10 comprises a focusing device 30 for focusing the first laser beam 16 onto a first position on the workpiece 12 and for focusing the second laser beam 20 onto a second position on the workpiece 12 that is different from the first position.

[0075] The focusing device 30 can be configured such that a distance between the first position and the second position is in a range of 0.5 gm to 5 mm, in particular 1 gm to 100 gm.

[0076] The amplifier device 26 may comprise a rod amplifier, a fiber, a slab amplifier and / or a disk amplifier.

[0077] The separating device 28 may comprise at least one dispersive element. This may be configured, for example, as an optical grating and / or a prism.

[0078] The separation device 28 can comprise at least two dispersive elements. The at least two dispersive elements can be configured such that a distance between the first and second laser beams 16, 20 can be adjusted by varying a distance and / or an orientation of the at least two dispersive elements relative to one another.

[0079] The separating device 28 can be configured such that the first and second laser beams 16, 20, after separation, have a distance in an angular space which lies in a range from 1 degree to 1 mrad.

[0080] The first and second laser devices 14, 18 can each comprise at least one pulsed laser and / or at least one CW laser. The device 10 can comprise at least one third laser device for generating a third laser beam with a third wavelength (not shown). The third laser device can comprise at least one pulsed laser or at least one CW laser.

[0081] The ratio of a spectral width of each of the first wavelength and the second wavelength to a spectral distance between the first wavelength and the second wavelength can be 1:5, in particular 1:10, preferably 1:20.

[0082] The first laser device 14 can comprise at least two pulsed lasers. The at least two, in particular all, pulsed lasers can each be configured to generate a partial beam with the same wavelength. At least two, in particular all, partial beams can be configured with pulse shifts. At least two, in particular all, partial beams can form the first laser beam 16.

[0083] The second laser device 18 can comprise at least two pulsed lasers. The at least two, in particular all, pulsed lasers can each be configured to generate a partial beam with the same wavelength. At least two, in particular all, partial beams can be configured with pulse shifts. At least two, in particular all, partial beams can form the second laser beam 20.

[0084] In the present case, the first and second laser devices 14, 18 each comprise a temperature control device 32 for varying a temperature of the first and second laser devices 14, 18, respectively. In the present case, the device 10 comprises a scanner optics 34 for moving the first and / or second laser beam 16, 20 on the workpiece 12. The scanner optics 34 can comprise a galvo scanner and / or a polygon scanner. In the present case, the scanner optics 34 are arranged in front of the focusing device 30.

[0085] In the present case, the device 10 comprises a converter device 36 for converting the first and second wavelengths. The respective wavelength can be halved or divided into thirds, for example. The converter device 36 is arranged in front of the scanner optics 34.

[0086] In the present case, the device 10 comprises a control device 38. The control device 38 is configured to control the first laser device 14, the second laser device 18, the separating device 28, the temperature control device 32 of the first laser device 14, the temperature control device 32 of the second laser device 18, and the scanner optics 34.

[0087] In the following, a method for machining a workpiece 12 by means of at least two laser beams 16, 20 is described with reference to the device 10 shown in Figure 1.

[0088] The procedure includes the following steps:

[0089] Generating a first laser beam 16 having a first wavelength by means of a first laser device 14. Generating a second laser beam 20 having a second wavelength different from the first wavelength by means of a second laser device 18.

[0090] Generating a superimposed laser beam 24 by superimposing the first and second laser beams 16, 20.

[0091] Amplifying the superimposed laser beam 24 .

[0092] Separating the superimposed laser beam 24 into the first and second laser beams 16, 20.

[0093] Focusing the first laser beam 16 to a first position on the workpiece 12 and focusing the second laser beam 20 to a second position on the workpiece 12 different from the first position.

[0094] The method may comprise at least one of the following steps:

[0095] Changing a distance between the first and the second laser beam 16 , 20 .

[0096] Generating the first and / or the second laser beam 16, 20 from at least two pulsed partial beams, wherein at least two, in particular all, partial beams have the same wavelength and are designed with a pulse shift relative to one another.

[0097] Varying a temperature of the first and / or second laser device 14, 18. Moving the first and / or second laser beam 16, 20 on the workpiece 12.

[0098] Converting the first and / or second wavelength .

[0099] To carry out the method, a device 10 according to the above embodiments, in particular the device 10 shown in Figure 1, can be used.

Claims

Patent claims 1. Device (10) for machining a workpiece (12) by means of at least two laser beams (16, 20), comprising: a first laser device (14) for generating a first laser beam (16) with a first wavelength, a second laser device (18) for generating a second laser beam (20) with a second wavelength different from the first wavelength, a superposition device (22) for generating a superimposed laser beam (24) by superimposing the first and second laser beams (16, 20), an amplifier device (26) for amplifying the superimposed laser beam (24), a separating device (28) for separating the superimposed laser beam (24) into the first and second laser beams (16, 20),a focusing device (30) for focusing the first laser beam (16) to a first position on the workpiece (12) and for focusing the second laser beam (20) to a second position on the workpiece (12) different from the first position.

2. Device (10) according to claim 1, characterized in that the amplifier device (26) comprises a rod amplifier, a fiber, a slab amplifier and / or a disk amplifier.

3. Device (10) according to claim 1 or 2, characterized in that the separating device (28) at least one dispersive element, in particular an optical grating and / or a prism.

4. Device (10) according to the preceding claim, characterized in that the separating device (28) comprises at least two dispersive elements which are arranged such that a distance between the first and the second laser beam (16, 20) can be adjusted by varying a distance and / or an orientation of the at least two dispersive elements relative to one another.

5. Device (10) according to one of the preceding claims, characterized in that the separating device (28) is arranged such that the first and the second laser beam (16, 20) after the separation have a distance in an angular space which lies in a range of 1 prad to 1 mrad.

6. Device (10) according to one of the preceding claims, characterized in that the first and the second laser device (14, 18) each comprise at least one pulsed laser or at least one CW laser, in particular wherein the device (10) comprises at least one third laser device for generating a third laser beam with a third wavelength, wherein the third laser device comprises at least one pulsed laser or at least one CW laser.

7. Device (10) according to one of the preceding claims, characterized in that a ratio of a spectral width of each of the first wavelength and the second wavelength to a spectral distance between the first wavelength and the second Wavelength is 1:5, in particular 1:10, preferably 1:

20.

8. Device (10) according to one of the preceding claims, characterized in that the first and / or the second laser device (14, 18) each comprise at least two pulse lasers, wherein the at least two, in particular all, pulse lasers are each set up to generate a partial beam with the same wavelength, wherein at least two, in particular all, partial beams are designed to be pulse-shifted, in particular wherein at least two, in particular all, partial beams form the first and / or the second laser beam (16, 20).

9. Device (10) according to one of the preceding claims, characterized in that the first and / or the second laser device (14, 18) comprises a tempering device (32) for varying a temperature of the first and / or the second laser device (14, 18).

10. Device (10) according to one of the preceding claims, characterized in that the device (10) comprises a scanner optics (34) for moving the first and / or the second laser beam (16, 20) on the workpiece (12).

11. Device (10) according to the preceding claim, characterized in that the scanner optics (34) comprises a galvo scanner and / or a polygon scanner.

12. Device (10) according to one of the preceding claims, characterized in that the device (10) comprises a converter device (36) for converting, in particular halving or thirding, the first and / or the second wavelength.

13. Device (10) according to one of the preceding claims, characterized in that the device (10) comprises at least one control device (38) for controlling the first laser device (14), the second laser device (18), the separating device (28), the tempering device (32) and / or the scanner optics (34).

14. Device (10) according to one of the preceding claims, characterized in that the focusing device (30) is arranged such that a distance between the first position and the second position is in a range of 0.5 pm to 5 mm, in particular 1 pm to 100 pm.

15. Method for machining a workpiece (12) by means of at least two laser beams (16, 20) comprising the steps: Generating a first laser beam (16) having a first wavelength by means of a first laser device (14); Generating a second laser beam (20) having a second wavelength different from the first wavelength by means of a second laser device (18); Generating a superimposed laser beam (24) by superimposing the first and second laser beams (16, 20); Amplifying the superimposed laser beam (24); Separating the superimposed laser beam (24) into the first and second laser beams (16, 20); Focusing the first laser beam (16) on a first position on the workpiece (12) and focusing the second laser beam (20) on a second position on the workpiece (12) different from the first position.

16. The method according to claim 15, characterized in that the method comprises the step: Changing a distance between the first and the second laser beam (16, 20).

17. The method according to claim 15 or 16, characterized in that the method comprises the step: Generating the first and / or the second laser beam (16, 20) from at least two pulsed partial beams, wherein at least two, in particular all, partial beams have the same wavelength and are designed with a pulse shift relative to one another.

18. Method according to one of claims 15 to 17, characterized in that the method comprises the step: Varying a temperature of the first and / or second laser device (14, 18).

19. Method according to one of claims 15 to 17, characterized in that the method comprises the step: Moving the first and / or second laser beam (16, 20) on the workpiece (12).

20. Method according to one of claims 15 to 19, characterized in that the method comprises the step: Converting the first and / or second wavelength .

21. Method according to one of claims 15 to 20, characterized in that a device (10) according to one of claims 1 to 14 is used to carry out the method.

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