CN113714634B

CN113714634B - Laser processing system and method

Info

Publication number: CN113714634B
Application number: CN202010450845.6A
Authority: CN
Inventors: 蒋峰; 杨德权; 张均; 雷剑; 吕张勇; 郝冀; 王英
Original assignee: Maxphotonics Co Ltd
Current assignee: Maxphotonics Co Ltd
Priority date: 2020-05-25
Filing date: 2020-05-25
Publication date: 2023-10-31
Anticipated expiration: 2040-05-25
Also published as: CN113714634A

Abstract

Embodiments of the present invention provide a laser processing system and method for generating a composite laser output to a workpiece, including a laser and a laser processing head; the laser is used for providing compound laser with at least one first light beam and at least one second light beam; the laser has an optical fiber, and the laser processing head is connected with the optical fiber and is used for guiding the composite laser output by the laser to the workpiece. The embodiment of the invention has the advantages of few used devices, low cost and good processing effect.

Description

Laser processing system and method

Technical Field

The invention relates to the technical field of laser, in particular to a laser processing method and a laser processing system.

Background

With the rapid development of optical fiber and semiconductor laser manufacturing technology, the output power of the optical fiber and semiconductor laser is greatly increased, and a composite processing technology of forming two or more beams of laser by utilizing single laser beam splitting or multiple laser composite can provide a feasible solving direction for high-quality precision processing.

In the prior art, two laser devices are used, and the light beams output by the two laser devices through two optical fibers are synthesized and output through a composite processing head. The two laser devices and the optical devices for beam combination are required, so that the cost is high, the complexity of optics and control of the whole system is greatly increased, the potential reliability hazards are caused, the size of the system is too large, the system is limited in some special application scenes, and the flexible processing capability of the composite laser is weakened.

Disclosure of Invention

In view of the above, embodiments of the present invention have been made to provide a laser processing method and a corresponding laser processing system that overcome or at least partially solve the above problems.

In order to solve the above problems, an embodiment of the present invention discloses a laser processing system for generating a composite laser output to a workpiece, including a laser and a laser processing head;

the laser is used for providing compound laser with at least one first light beam and at least one second light beam;

the laser has an optical fiber, and the laser processing head is connected with the optical fiber and is used for guiding the composite laser output by the laser to a workpiece.

Optionally, the device further comprises a control device for adjusting the power value of the first light beam to adjust the spot energy distribution of the first light beam irradiated to the workpiece, and/or adjusting the power value of the second light beam to adjust the spot energy distribution of the second light beam irradiated to the workpiece.

Optionally, the control device is further configured to control the power value of the first light beam and the power value of the second light beam according to the material of the workpiece.

Optionally, the control device is further configured to adjust the defocus amount of the first beam to adjust the spot profile and energy distribution of the first beam irradiated to the workpiece, or adjust the defocus amount of the second beam to adjust the spot profile and energy distribution of the second beam irradiated to the workpiece.

Optionally, the laser processing head is provided with a single fibre optic connector through which the optical fibres of the laser are fitted at the laser processing head to direct the first and second beams onto the workpiece.

Optionally, the laser has a single laser module for transmitting the pump light not absorbed in the fiber cladding out to form a first light beam, and transmitting the amplified signal light in the fiber core out to form a second light beam.

Optionally, the laser has a single laser module, and the single laser module is configured to transmit the pump light that is not absorbed in the fiber cladding and the signal light that leaks into the cladding to form a first beam, and transmit the amplified signal light in the fiber core and the pump light that leaks into the fiber core to form a second beam.

Optionally, the laser is a single resonant cavity laser or a MOPA laser.

Optionally, the wavelength of the first light beam is different from the wavelength of the second light beam, the center wavelength of the second light beam is 1030-2140nm, and the center wavelength of the first light beam is 915-1550nm.

Optionally, the first light beam has a center wavelength of 915nm and the second light beam has a center wavelength of 1080nm.

The embodiment of the invention also discloses a laser processing method, which comprises the following steps:

irradiating a laser beam having at least a first beam and a second beam on a surface of a workpiece; the first light beam irradiates the workpiece to form a first light spot, the second light beam irradiates the workpiece to form a second light spot, the second light spot is positioned in the first light spot, and the energy of the second light spot and the energy of the first light spot are adjustable.

Optionally, the energy distribution of the first beam is a flat-top distribution, and the energy distribution of the second beam is a gaussian distribution.

Optionally, the method further comprises: the power value of the first light beam is adjusted to adjust the light spot energy distribution of the first light beam irradiated to the workpiece, and/or the power value of the second light beam is adjusted to adjust the light spot energy distribution of the second light beam irradiated to the workpiece.

Optionally, the method further comprises: and controlling the power value of the first light beam and the power value of the second light beam according to the material of the workpiece.

Optionally, the method further comprises: the defocus amount of the first light beam is adjusted to adjust the light spot profile and the energy distribution of the first light beam irradiated to the workpiece, or the defocus amount of the second light beam is adjusted to adjust the light spot profile and the energy distribution of the second light beam irradiated to the workpiece.

Optionally, the irradiating the laser having at least one first beam and at least one second beam on the surface of the workpiece includes:

and transmitting the unabsorbed pump light in the optical fiber cladding of the laser and the signal light leaked into the cladding to form a first light beam, and transmitting the amplified signal light in the optical fiber core and the pump light leaked into the optical fiber core to form a second light beam.

the first beam and the second beam are directed to a workpiece by a single fiber optic splice laser processing head.

Optionally, the wavelength of the first light beam is different from the wavelength of the second light beam, the center wavelength of the first light beam is 915-1550nm, and the center wavelength of the second light beam is 1030-2140nm.

The embodiment of the invention has the following advantages:

the laser processing system provided by the embodiment of the invention provides compound laser with at least one first light beam and at least one second light beam through a laser; the laser has an optical fiber, and the laser processing head is connected with the optical fiber for guiding the composite laser output by the laser onto the workpiece. The first light beam can be utilized to preheat the surface of the workpiece to form a smoother molten pool, the second light beam is utilized to form a keyhole on the preheated area of the surface of the workpiece, and therefore larger penetration is obtained, and the processing effect is good. The two light beams are not required to be combined by using an additional composite welding head, so that the processing cost can be reduced. And because the first light beam and the second light beam are transmitted by the same optical fiber, the processing direction is not required in principle, and the processing technology can be simplified.

Drawings

FIG. 1 is a flow chart of steps of an embodiment of a laser processing method of the present invention;

FIG. 2 is a schematic diagram showing the energy distribution of a composite laser in an actual state;

FIG. 3 is a schematic diagram of a composite laser energy distribution in an ideal state;

FIG. 4 is a schematic diagram of another composite laser energy distribution under ideal conditions;

FIG. 5 is a schematic diagram of another composite laser energy distribution under ideal conditions;

FIG. 6 is a schematic diagram of another composite laser energy distribution under ideal conditions;

FIG. 7 is a block diagram of an embodiment of a laser processing system of the present invention;

FIG. 8 is a block diagram of a laser in an embodiment of the invention;

FIG. 9 is a block diagram of a laser in one example;

fig. 10 is a block diagram of a laser in another example.

Detailed Description

In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description.

Referring to fig. 1, a flowchart illustrating steps of an embodiment of a laser processing method according to the present invention may specifically include the following steps:

step 101, irradiating laser with at least one first beam and at least one second beam on the surface of a workpiece; the first light beam irradiates the workpiece to form a first light spot, the second light beam irradiates the workpiece to form a second light spot, the second light spot is positioned in the first light spot, and the energy of the second light spot and the energy of the first light spot are adjustable.

The at least one first beam and the second beam may be directed to the workpiece by a single fiber optic joint laser processing head.

In an embodiment of the present invention, the step 101 may include the following sub-steps:

and S11, transmitting unabsorbed pump light in an optical fiber cladding of a laser to form a first light beam, and transmitting amplified signal light in the optical fiber core to form a second light beam.

Specifically, the unabsorbed pump light in the optical fiber cladding of a laser and the signal light leaked into the cladding can be transmitted to form a first light beam, and the amplified signal light in the optical fiber core and the pump light leaked into the optical fiber core can be transmitted to form a second light beam;

the unabsorbed pump light and the signal light leaking from the core into the cladding may be transmitted in the cladding of the optical fiber, and the amplified signal light and the pump light leaking from the cladding into the core may be transmitted in the core of the optical fiber.

The substep S11 may further include:

sub-step S111 of transmitting the amplified signal light to the core of the active optical fiber and transmitting the unabsorbed pump light to the cladding of the active optical fiber;

substep S112, transmitting the pump light which is not absorbed in the cladding of the active optical fiber and the signal light which leaks into the cladding from the core to form a first light beam, and transmitting the amplified signal light in the core of the active optical fiber and the pump light which leaks into the core from the cladding to form a second light beam.

The laser may further include a passive optical fiber connected after the active optical fiber, and the sub-step S112 may further include:

substep S1121, maintaining the pump light output from the cladding of the active optical fiber and the signal light leaked from the core into the cladding in the cladding of the passive optical fiber after being connected to the active optical fiber for transmission, and maintaining the amplified signal light output from the core of the active optical fiber and the pump light leaked from the cladding into the core in the core of the passive optical fiber for transmission;

when the number of the cladding layers of the passive optical fiber after being connected to the active optical fiber is larger than that of the active optical fiber, the pump light output from the cladding layers of the active optical fiber and the signal light leaked from the core into the cladding layers are transmitted into at least one cladding layer of the passive optical fiber.

Substep S1122, transmitting the pump light not absorbed in the cladding of the passive optical fiber and the signal light leaking into the cladding from the core to form a first light beam, and transmitting the amplified signal light in the core of the passive optical fiber and the pump light leaking into the core from the cladding to form a second light beam.

And a substep S12, irradiating the laser of the at least one first beam and the second beam on the surface of the workpiece.

In the embodiment of the invention, the first light beam and the second light beam are transmitted in one optical fiber of the laser, and the energy transmission of the fiber core and the cladding of the optical fiber forms a point-ring-shaped energy distribution mode. Dot-loop refers to the shape of one or more rings from a point in the center and around the center, and a typical dot-loop energy distribution laser is a straw hat laser.

The proportion of the pump light absorbed by the active fiber is determined by the absorptivity of the active fiber. In an embodiment of the present invention, the absorption rate of the active optical fiber may be set to be greater than 0 and less than 15dB, so that the pump light is only absorbed in a small portion. In one example, the absorptivity of the active optical fiber may be set to be greater than 0 and less than 10dB. In another example, the absorptivity of the active optical fiber may be set to be greater than 0 and less than 8dB.

The absorption rate (dB) of the active optical fiber is determined by the optical fiber length (m) and the absorption coefficient (dB/m) of the optical fiber itself, so that the absorption rate can be adjusted by setting the length of the active optical fiber, and compared with the existing optical fiber laser, the active optical fiber length in the embodiment of the present invention is shorter. In one example, the length of the active optical fiber may be less than 50 meters. In another example, the length of the active optical fiber may be less than 30 meters. In another example, the length of the active optical fiber may be less than 20 meters. In another example, the length of the active optical fiber may be less than 10 meters. In embodiments of the present invention, the active optical fiber includes a core and a double or multi-clad layer.

Fig. 2 is a schematic diagram showing a composite laser energy distribution in an actual state. In one example of the embodiment of the invention, the energy distribution of the first beam is flat-top distribution, the beam energy uniformly acts on the surface of the workpiece, and the surface of the workpiece is subjected to heat conduction welding, so that the surface of the workpiece is smooth; however, the penetration is shallow because the energy density of the light beam is low and the pinhole effect is not easy to form. The energy distribution of the second light beam is Gaussian or Gaussian-like, the light beam is concentrated in energy, the surface of the workpiece is subjected to deep-melting welding, small holes are easy to form, the penetration is large, and key holes are formed on the surface of the workpiece, but splashing is easy to form in the process, and the surface forming is affected. The two wavelength light beams are combined to act on the workpiece, so that the advantages of the two wavelength light beams can be exerted, the certain weld depth is ensured, meanwhile, splashing is restrained, and the surface forming is improved.

A schematic diagram of the energy distribution of a composite laser in an ideal state is shown in fig. 3. The composite laser includes a first beam and a second beam, the first beam having a wavelength different from the second beam. The first light beam surrounds the second light beam, and the cross section of the first light beam is annular. As shown in fig. 3, the first beam and the second beam may be closely coupled. The first beam may be unabsorbed pump light from the cladding of the active fiber that is of lower power density and lower brightness than the second beam. In practice, signal light leaking from the core of the active fiber may also be transmitted to the cladding. The power of the first beam is related to the pump power and the active fiber parameters (including core diameter, absorption, doping species, length).

The second light beam has a cross section of a point shape, a square shape, a round shape or a quasi-round shape, and the second light beam can be amplified signal light output from the fiber core of the active optical fiber. In practice, pump light leaking from the cladding of the active fiber may also be transmitted to the core. The power of the second beam is related to the pump power and the active fiber parameters (including core diameter, numerical aperture NA, absorptivity, doping species, length).

Referring to fig. 4, another schematic diagram of the energy distribution of the composite laser in an ideal state is shown. The composite laser includes a first beam and a second beam, the second beam having a power greater than the first beam. An annular area exists between the first beam and the second beam, as shown in fig. 4, and the concave portion between the first beam and the second beam is an annular area, and the annular area has no laser radiation or only stray radiation, and therefore has no energy or only low energy.

The recess may be created by fitting a particular fiber optic product, such as a standard QBH energy-delivery fiber. For example, a portion of the QBH enabled fiber is an F-doped low index layer, and dishing occurs in this portion.

Referring to fig. 5, another schematic diagram of the energy distribution of the composite laser in an ideal state is shown. The composite laser comprises a first beam and a second beam, the power of the second beam is smaller than that of the first beam, and a concave part is arranged between the second beam and the first beam. In the embodiment of the invention, when the first light beam comprises a plurality of first light beams, the plurality of first light beams are sequentially and closely connected or the annular area exists between any two adjacent first light beams, and the annular area has no laser radiation or only stray radiation.

Referring to fig. 6, another schematic diagram of the energy distribution of the composite laser in an ideal state is shown. The composite laser includes two first beams and a second beam, there is an annular region between the second beam and the first beams, and there is also an annular region between the two first beams.

In one example, the first light beam may have a wavelength different from the second light beam, the second light beam may have a center wavelength of 1030-2140nm, and the first light beam may have a center wavelength of 915-1550nm. In another example, the center wavelength of the second light beam may be 1080nm and the center wavelength of the first light beam may be 915nm.

In the embodiment of the invention, the first light spot of the first light beam and the second light spot of the second light beam can be controlled to move, and in the moving process, the first light beam preheats the surface of the workpiece to form a molten pool, and the second light beam forms a keyhole on the preheated area of the surface of the workpiece.

The first light beam and the second light beam with different wavelengths have different forming characteristics on the surface of the workpiece, and the two light beams with different wavelengths are combined to act on the workpiece, so that the advantages of the two light beams can be exerted.

When the workpiece is processed, the light spot of the first light beam and the light spot of the second light beam can be controlled to move according to a set track. Because the first light beam surrounds the second light beam, the first light beam can generate a preheating effect on the surface of the workpiece in the moving process in any direction, the absorption rate of the metal workpiece can be greatly improved due to the rising of the temperature, and the formation of a key hole by the second light beam is facilitated. In addition, the first beam energy behind the welding seam can expand the range of the molten pool in a certain range, and the closing time of the keyhole is prolonged, so that splashing is reduced.

According to the laser processing method, laser with at least one first light beam and at least one second light beam is irradiated on the surface of a workpiece; the first light beam irradiates the workpiece to form a first light spot, the second light beam irradiates the workpiece to form a second light spot, the second light spot is located in the first light spot, the surface of the workpiece can be preheated by the first light beam to form a smoother molten pool, and a keyhole is formed in a preheated area of the surface of the workpiece by the second light beam, so that larger penetration is obtained, and the processing effect is good. The two light beams are not required to be combined by using an additional composite welding head, so that the processing cost can be reduced. And because the first light beam and the second light beam are transmitted by the same optical fiber, the processing direction is not required in principle, and the processing technology can be simplified.

When the workpiece is processed, the light spot energy distribution of the first light beam irradiated to the workpiece can be changed, the light spot energy distribution of the second light beam irradiated to the workpiece can be changed, and the specific gravity of the characteristics of the light beams with different wavelengths in the welding process is controlled so as to change the processing effect of the light beams on the surface of the workpiece.

In one aspect, the spot energy distribution impinging on the surface of the workpiece may be varied by adjusting the power level of the beam. Specifically, the power value of the first beam may be adjusted to adjust the spot energy distribution of the first beam irradiated to the workpiece, and the power value of the second beam may be adjusted to adjust the spot energy distribution of the second beam irradiated to the workpiece.

On the other hand, due to the different wavelengths, the first light beam and the second light beam have different focal positions (basically the positions of the minimum light spots of the light beams with the respective wavelengths) after passing through the focusing optical lens inside the welding head, so that two-wavelength bifocal distributions are formed, and by changing the defocus amount (the position of the workpiece relative to the focal point of the light beam), the energy distribution of the two-wavelength light beams on the surface of the workpiece can be correspondingly adjusted. For example: the smaller the spot of the first beam, the more pronounced the characteristics of the first beam when the workpiece is closer to the focal position of the first beam; the smaller the spot of the second beam, the more pronounced the characteristics of the second beam when the workpiece is closer to the focal position of the second beam.

The defocus amount of the first beam may be adjusted to adjust the spot profile and the spot energy distribution of the first beam impinging on the workpiece, or the defocus amount of the second beam may be adjusted to adjust the spot profile and the spot energy distribution of the second beam impinging on the workpiece.

For workpieces of different materials, the power value of the first light beam and the power value of the second light beam can be quantitatively controlled, so that a good processing effect is obtained. For example, taking stainless steel as an example, on the premise of unchanged welding speed and defocusing amount, the first beam is not lower than 700 watts, the second beam energy is not lower than 500 watts, good surface forming and better splash control can be obtained, and a molten pool is slightly deepened.

In the embodiment of the invention, the width of the molten pool can be realized by adjusting the energy of a laser beam, the welding speed, the defocusing amount and the like. The width of the melt pool can be varied by increasing the energy of the first beam and adjusting the amount of defocus under certain conditions, such as constant welding speed and constant energy of the second beam.

In the embodiment of the invention, the second light beam plays a decisive role in the formation process of the keyhole, so that deeper welding seams can be obtained by increasing the energy of the second light beam. In addition, the depth of the welding seam can be changed by adjusting the defocusing amount of the second light beam and changing the welding speed.

It should be noted that, for simplicity of description, the method embodiments are shown as a series of acts, but it should be understood by those skilled in the art that the embodiments are not limited by the order of acts, as some steps may occur in other orders or concurrently in accordance with the embodiments. Further, those skilled in the art will appreciate that the embodiments described in the specification are presently preferred embodiments, and that the acts are not necessarily required by the embodiments of the invention.

Referring to fig. 7, there is shown a block diagram of an embodiment of a laser processing system of the present invention, which may include, in particular, a laser 20, a processing head 21;

The laser 20 is configured to provide a composite laser having at least a first beam and a second beam;

The laser processing system can further comprise a control device for controlling the light spot of the first light beam and the light spot of the second light beam to move, wherein in the moving process, the first light beam preheats the surface of the workpiece to form a molten pool, and the second light beam forms a keyhole on the preheated area of the surface of the workpiece.

The control device can comprise an XYZ three-axis moving assembly, and can respectively control the laser and the processing head to move in the X axis, the Y axis and the Z axis, so as to control the spot movement of the output laser.

Both the first beam and the second beam are transmitted in one optical fiber of the laser. The optical fiber may be a single-core optical fiber comprising a core and a plurality of cladding layers, the optical fiber being configured to provide at least a first light beam transmitted in the cladding layers and a second light beam transmitted in the core. Wherein the wavelength of the first light beam may be different from the wavelength of the second light beam. In one example, the second beam may have a center wavelength of 1030-2140nm and the first beam may have a center wavelength of 915-1550nm. In another example, the first beam may have a center wavelength of 915nm and the second beam may have a center wavelength of 1080nm.

In an embodiment of the present invention, the control device is further configured to adjust a power value of the first light beam to adjust a spot energy distribution of the first light beam irradiated to the workpiece, and/or adjust a power value of the second light beam to adjust a spot energy distribution of the second light beam irradiated to the workpiece.

In this embodiment of the present invention, the control device is further configured to control the power value of the first light beam and the power value of the second light beam according to a material of the workpiece.

In an embodiment of the present invention, the control device is further configured to adjust a defocus amount of the first beam to adjust a spot profile and an energy distribution of the first beam irradiated to the workpiece, or adjust a defocus amount of the second beam to adjust a spot profile and an energy distribution of the second beam irradiated to the workpiece.

In an embodiment of the invention, the laser processing head 21 is provided with a single fibre optic connector through which a fibre of the laser 20 is fitted at the laser processing head 21 to direct the first and second beams onto the workpiece.

Since both the first and second beams are transmitted in one optical fiber, only a single fiber splice is required to adapt the first and second beams to the laser processing head. Compared with the prior art that two light beams with two wavelengths are transmitted through two optical fibers, the scheme that the double-optical-fiber connector is matched with the laser processing head is needed, and the cost is lower.

The laser 20 has a single laser module for transmitting the unabsorbed pump light in the fiber cladding out to form a first beam and transmitting the amplified signal light in the fiber core out to form a second beam. Specifically, the single laser module includes an active optical fiber, where the active optical fiber is used to partially absorb pump light and amplify signal light, the fiber core of the active optical fiber is used to transmit signal light, the cladding of the active optical fiber is used to transmit unabsorbed pump light, and the beam output by the active optical fiber is transmitted to obtain a composite laser with a first beam and a second beam. Compared with the scheme of generating two wavelength light beams through two laser modules in the prior art, the embodiment of the invention generates the first light beam and the second light beam through the single laser module, and has lower cost.

The single laser module is also used for transmitting unabsorbed pump light in the optical fiber cladding and signal light leaked into the cladding to form a first light beam, and transmitting amplified signal light in the optical fiber core and pump light leaked into the optical fiber core to form a second light beam.

In the embodiment of the invention, the laser can be a single resonant cavity laser or a MOPA laser. In a single cavity laser, the cavity may be formed of fiber bragg gratings FBGs disposed at both ends of an active fiber, and pump light is transmitted in the cavity, and a portion is absorbed by the active fiber, thereby generating signal light. In the MOPA laser, a seed light source supplies signal light to an active optical fiber, which absorbs pump light to amplify the signal light.

The absorption rate (dB) of the active optical fiber is determined by the optical fiber length (m) and the absorption coefficient (dB/m) of the optical fiber itself, so that the absorption rate can be adjusted by setting the length of the active optical fiber, and compared with the existing optical fiber laser, the active optical fiber length in the embodiment of the present invention is shorter. In one example, the length of the active optical fiber may be less than 50 meters. In another example, the length of the active optical fiber may be less than 30 meters. In another example, the length of the active optical fiber may be less than 20 meters. In another example, the length of the active optical fiber may be less than 10 meters.

Referring to fig. 8, a structure of a laser according to an embodiment of the present invention is shown. Wherein the laser may comprise: a pump assembly 1 for providing pump light, an active optical fiber 2, an optical fiber output device 3; the active optical fiber 2 is used for partially absorbing pump light and amplifying signal light, the fiber core of the active optical fiber 2 is used for transmitting the signal light, and the cladding of the active optical fiber 2 is used for transmitting the pump light which is not absorbed; and transmitting the light beam output by the active optical fiber 2 to obtain the composite laser with at least one first light beam and at least one second light beam.

The laser of the embodiment of the invention can be a laser with an all-fiber structure, namely devices in the laser are connected through optical fibers or are connected by self-contained optical fibers.

The pump assembly 1 may comprise a plurality of pump light sources 11 and a combiner 12. The output power of the pump light source 11 can be adjusted to adjust the power of the pump light input to the active optical fiber 2 to form the composite laser spot output with different energy proportion profiles.

The combiner 12 may be a high power n+1: the beam combiner 1 comprises a plurality of input optical fibers and an output optical fiber, each pump light source 11 can be connected with one input optical fiber, and the pump light output by the pump light sources 11 is coupled and output from the output optical fiber by the beam combiner 12.

The pump light source 11 may be a semiconductor pump light source, or may be any laser light source output by an optical fiber. For example, the plurality of pump light sources 11 may include at least one of semiconductor laser light, direct semiconductor laser light, and short wavelength fiber laser light. For example, the multiple pump light sources may be all semiconductor lasers, or part of the pump light sources may be direct semiconductor lasers, and the rest of the pump light sources may be short-wavelength fiber lasers. The kind of the pumping light source can be set according to actual needs.

In the embodiment of the present invention, the wavelength of the second beam and the wavelength of the first beam of the composite laser may be set according to the wavelength of the pump light source 11 and the doping element of the active optical fiber 2. The doping elements may include ytterbium (Yb), erbium (Er), thulium (Tm), and the like.

For example, the pumping wavelength is 915nm, the active optical fiber is doped with Yb, the wavelength of the signal light can be in the range of 1030-1090 nm, the wavelength of the second light beam can be in the range of 1030-1090 nm, the wavelength bandwidth is in the range of 0.5-20 nm, and the power is not less than 100W; the wavelength of the first light beam includes 915nm.

The plurality of pump light sources 11 may be pump light sources of the same wavelength or pump light sources of different wavelengths. Using pump light sources 11 of different wavelengths, a composite laser of different wavelength combinations can be generated.

In the embodiment of the invention, the device can also comprise a control device connected with the pump light source 11, wherein the control device is used for adjusting the power of the pump light to form the composite laser spot output with different energy ratio profiles.

The control means may control the pump light power output from each pump light source 11, respectively. For example, the control device controls the partial pump light source 11 to be turned on or off, and the control device controls the partial pump light source 11 to increase or decrease the output pump light power.

In the embodiment of the present invention, the active optical fiber 2 may be a double-clad or multi-clad active optical fiber, and the optical fiber output device 4 may include a double-clad or multi-clad first optical fiber and an output head.

In the embodiment of the present invention, the cladding of the first optical fiber is used for transmitting the pump light which is not absorbed in the active optical fiber 2, and the core of the first optical fiber is used for transmitting the signal light in the active optical fiber 2.

In the embodiment of the present invention, the cladding layer of the first optical fiber is used for transmitting the pump light which is not absorbed in the active optical fiber 2 and the signal light which leaks into the cladding layer, and the core of the first optical fiber is used for transmitting the signal light in the active optical fiber 2 and the pump light which leaks into the core.

The numerical aperture of the core of the active optical fiber 2 and the numerical aperture of the core of the first optical fiber are designed to control a portion of the signal light to enter the cladding layer such that the laser transmission mode of the core of the active optical fiber 2 is the same as the laser transmission mode of the core of the first optical fiber.

The numerical aperture of the cladding of the active optical fiber 2 and the numerical aperture of the cladding of the first optical fiber are designed to control part of the pump light to enter the fiber core, so that the laser transmission module of the cladding of the active optical fiber 2 is identical to the laser transmission mode of the corresponding cladding in the first optical fiber.

The cladding of a multi-clad optical fiber may be divided into an inner cladding and an outer cladding. For a double-clad fiber, the cladding close to the fiber core is the inner cladding, and the cladding far from the fiber core is the outer cladding. For multi-clad optical fibers with more than three cladding layers, the cladding layer farthest from the optical fiber is an outer cladding layer, and the rest cladding layers are inner cladding layers. The overclad is typically a low index material that is not used to transmit laser light.

In the embodiment of the present invention, among the plurality of cladding layers of the active optical fiber 2, the cladding layers other than the outer cladding layer may be used to transmit the pump light that is not absorbed. Among the multiple claddings of the first optical fiber of the multiple cladding, the cladding other than the outer cladding is used for transmitting the pump light that is not absorbed.

In one example, the number of cladding layers of the active optical fiber 2 may be the same as the number of cladding layers of the first optical fiber.

In another example, the number of the cladding layers of the active optical fiber 2 may be smaller than the number of the cladding layers of the first optical fiber, in this example, the active optical fiber 2 and the first optical fiber are matched and arranged by tapering or direct fusion, so that the cladding light transmitted in the cladding layer of the active optical fiber 2 can enter the specific cladding layer of the first optical fiber according to the design requirement. For example, the active fiber is double clad and the first fiber is four clad. The laser light transmitted from the cladding of the active optical fiber 2 may be diffused into at least one cladding of the first optical fiber for transmission. Specifically, the active optical fiber and the first optical fiber can be subjected to independent tapering treatment through the optical fiber cladding or simultaneous tapering of the cladding and the fiber core to match the fiber size and NA setting, so that pump light transmitted in the active optical fiber cladding can enter at least one cladding of the first optical fiber.

In an embodiment of the present invention, the optical fiber output device may further include a stripper; the stripper is used for stripping the laser transmitted in the outermost layer or the outermost multi-layer cladding of the first optical fiber, and particularly can strip unnecessary cladding light according to actual needs.

In an embodiment of the present invention, the laser may further include: a second optical fiber 4 connected between the active optical fiber 2 and the optical fiber output device 3, and a third optical fiber 5 connected between the combiner 12 and the active optical fiber 2. The first, second and third optical fibers 4, 5 are all passive optical fibers.

The second optical fiber 4 and the third optical fiber 5 may be double-clad or multi-clad optical fibers, the second optical fiber 4 being matched with the first optical fibers of the active optical fiber 2 and the optical fiber output device 3. In particular, the core of the second optical fiber 4 may be used for transmitting signal light, and the cladding of the second optical fiber 4 may be used for transmitting unabsorbed pump light. The core of the second optical fiber 4 is also used for transmitting pump light leaking into the core, and the cladding of the second optical fiber 4 is also used for transmitting signal light leaking into the cladding.

In an embodiment of the present invention, the spot parameters (including the spot size and the spot shape) of the second beam of the composite laser are related to the core parameters of the active fiber and the core parameters of the passive fiber. Wherein the core parameters include a numerical aperture NA.

In the embodiment of the present invention, the spot parameters (including the spot shape and the spot size) of the first beam of the composite laser are related to the cladding diameters and numerical aperture NA of the second optical fiber 4 and the first optical fiber, and the combiner parameters.

The combiner parameters refer to process parameters of a combiner, and when the combiner is manufactured, the combiner is manufactured according to the input optical fiber and the output optical fiber to be connected, and the manufacturing process parameters are set for the input optical fiber and the output optical fiber to be connected. In the embodiment of the present invention, the combiner parameter may be set according to the input optical fiber connected to the pump light source and the third optical fiber 5, so that the effect of the third optical fiber 5 on the output laser light may be attributed to the combiner parameter, and the combiner parameter may include the parameter of the input optical fiber of the pump light source and the parameter of the third optical fiber 5.

In practice, the cladding diameter, numerical aperture NA, and combiner parameters of the second optical fiber 4 and the first optical fiber parameters may be set according to actual needs, so as to set the spot parameters of the first beam of the output composite laser. The second optical fiber 4 may be provided with the same fiber parameters as the third optical fiber 5.

In one example of an embodiment of the present invention, the laser may further include: and the fiber Bragg gratings FBG6 are arranged at two ends of the active fiber to form a resonant cavity. Referring to fig. 9, a block diagram of a laser in one example is shown.

The fiber bragg grating FBG6 may include an HR (High Reflector) FBG and an OC (Out Coupler) FBG, wherein the HR FBG is disposed between the pump assembly 1 and the active fiber 2, the OC FBG is disposed between the active fiber 2 and the fiber output device 3, and the HR FBG and the OC FBG constitute a resonant cavity. The pump light is transmitted in the cavity, and a part of the pump light is absorbed by the active optical fiber 2, thereby generating signal light, and the other part of the pump light is output from the cavity. The optical fiber output device 3 outputs laser light output from the resonator.

In another example of the embodiment of the present invention, the laser may further include: a seed light source for providing signal light. Referring to fig. 10, a block diagram of a laser in another example is shown. The signal light output by the seed light source 7 and the pump light output by the pump assembly 1 are transmitted and coupled to the active optical fiber 2, and the active optical fiber 2 absorbs the pump light to amplify the signal light.

The laser that supplies the signal light through the seed light source may be referred to as a MOPA (Master Oscillator Power-Amplifier, power Amplifier of the master oscillator) laser.

In this example, each of the pump light source 11 and the seed light source 7 may be connected to one input optical fiber of the beam combiner 12, and the pump light outputted from the plurality of pump light sources and the signal outputted from the seed light source 7 are optically coupled by the beam combiner 12 and outputted from the output optical fiber of the beam combiner 12 to the active optical fiber 2.

The pump light and the signal light output from the output fiber of the beam combiner 12 may be received by the active fiber 2, and the pump light is absorbed by the active fiber 2 to amplify the signal light.

In an alternative embodiment, the length of the active optical fiber may be set to 0, that is, a structure in which the signal light and the pump light are directly output by the beam combiner is formed, and the final light spot output characteristic is selected by different matching of the output optical fiber and the beam combiner.

The seed light source 7 may comprise a single resonant cavity fiber laser, or a fiber-coupled thin-sheet laser, or a diode-pumped solid-state laser (e.g., nd-YAG laser), or a semiconductor laser.

In this example, a control device is also included in connection with the seed light source for adjusting the output power of the seed light source to form a composite laser spot output of different energy ratio profiles.

In this example, the wavelength of the second light beam and the wavelength of the first light beam may be set according to the wavelength of the seed light source 7, the wavelength of the pump light source 11, and the doping element of the active optical fiber 2.

The power of the second beam is related to the seed light source power, the pump power and the active fiber parameters (including core diameter, numerical aperture NA, absorptivity, dopant, length).

In practical use, as the active optical fiber parameters are fixed, the power of the second light beam and the power of the first light beam can be adjusted by independently and continuously adjusting the power of the seed light source or the pump power, so that the light spot output with different energy proportion profiles is formed.

In one example, the pump light and the signal light have different wavelengths, the signal light may have a center wavelength of 1030-2140nm, and the pump light may have a center wavelength of 915-1550nm. In another example, the center wavelength of the signal light may be 1080nm and the center wavelength of the pump light may be 915nm.

In embodiments of the present invention, the laser processing system may be used for laser welding, laser cladding, or other laser applications, with further laser welding being laser continuous welding. The laser continuous welding is different from the spot welding in processing mode, and the laser processing system can continuously output laser to process the workpiece.

The laser processing system of the embodiment of the invention can process the workpiece by outputting the first light beam and the second light beam on the same optical fiber of the laser, preheat the surface of the workpiece by the first light beam to form a smoother molten pool, and form a keyhole on the preheated area of the surface of the workpiece by the second light beam to obtain larger penetration depth. The two light beams are combined without using an additional composite welding head, so that the processing cost is reduced.

In this specification, each embodiment is described in a progressive manner, and each embodiment is mainly described by differences from other embodiments, and identical and similar parts between the embodiments are all enough to be referred to each other.

It will be apparent to those skilled in the art that embodiments of the present invention may be provided as a method, apparatus, or computer program product. Accordingly, embodiments of the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, embodiments of the invention may take the form of a computer program product on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) having computer-usable program code embodied therein.

Embodiments of the present invention are described with reference to flowchart illustrations and/or block diagrams of methods, terminal devices (systems), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing terminal device to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing terminal device, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. It is therefore intended that the following claims be interpreted as including the preferred embodiment and all such alterations and modifications as fall within the scope of the embodiments of the invention.

Finally, it is further noted that relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or terminal that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or terminal. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article or terminal device comprising the element.

The foregoing has outlined a laser processing method and a laser processing system according to the present invention, wherein specific examples are provided herein to illustrate the principles and embodiments of the present invention, and the above examples are provided to assist in understanding the method and core idea of the present invention; meanwhile, as those skilled in the art will have variations in the specific embodiments and application scope in accordance with the ideas of the present invention, the present description should not be construed as limiting the present invention in view of the above.

Claims

1. A laser processing system for generating a composite laser output to a workpiece, comprising a laser and a laser processing head;

the laser is provided with an optical fiber A, and the laser processing head is connected with the optical fiber A and is used for guiding the composite laser output by the laser to a workpiece;

the laser comprises a pumping assembly for providing pumping light, an active optical fiber and an optical fiber output device;

the active optical fiber is double-clad or multi-clad active optical fiber, and the optical fiber output device comprises a double-clad or multi-clad first optical fiber and an output head; the cladding layer of the first optical fiber is used for transmitting the non-absorbed pump light in the active optical fiber and the signal light leaked into the cladding layer, and the fiber core of the first optical fiber is used for transmitting the signal light in the active optical fiber and the pump light leaked into the fiber core;

the first light beam is formed by transmitting unabsorbed pump light in the cladding of the active optical fiber and signal light leaking into the cladding from the fiber core, and the second light beam is formed by transmitting amplified signal light in the fiber core of the active optical fiber and pump light leaking into the fiber core from the cladding;

The numerical aperture NA of the fiber core of the active optical fiber and the numerical aperture NA of the fiber core of the first optical fiber are designed to control part of signal light to enter the cladding;

the numerical aperture NA of the cladding of the active optical fiber and the numerical aperture NA of the cladding of the first optical fiber are designed to control the partial pump light entering the core.

2. The laser processing system of claim 1, further comprising a control device for adjusting the power level of the first beam to adjust the spot energy distribution of the first beam to the workpiece and/or adjusting the power level of the second beam to adjust the spot energy distribution of the second beam to the workpiece.

3. The laser processing system of claim 2, wherein the control device is further configured to control the power value of the first beam and the power value of the second beam according to a material of the workpiece.

4. The laser processing system of claim 2, wherein the control device is further configured to adjust the defocus amount of the first beam to adjust the spot profile and energy distribution of the first beam impinging on the workpiece or to adjust the defocus amount of the second beam to adjust the spot profile and energy distribution of the second beam impinging on the workpiece.

5. The laser processing system of claim 1, wherein the laser processing head is provided with a single fiber joint through which the optical fiber a of the laser is adapted at the laser processing head to direct a first beam and a second beam onto the workpiece.

6. The laser processing system of claim 1, wherein the laser has a single laser module for transmitting the pump light not absorbed in the cladding of the optical fiber a and the signal light leaking into the cladding to form a first beam, and transmitting the amplified signal light in the core of the optical fiber a and the pump light leaking into the core to form a second beam.

7. The laser processing system of claim 1, wherein the laser is a single resonant cavity laser or a MOPA laser.

8. The laser processing system of claim 1, wherein a wavelength of the first beam is different from a wavelength of the second beam.

9. The laser processing system of claim 1, wherein the second beam has a center wavelength of 1030-2140nm and the first beam has a center wavelength of 915-1550nm.

10. The laser processing system of claim 1, wherein the first beam has a center wavelength of 915nm and the second beam has a center wavelength of 1080nm.

11. A laser processing method, characterized by being applied to the laser processing system of claim 1, comprising:

irradiating the laser of at least one first beam and at least one second beam provided by the laser on the surface of the workpiece; the first light beam irradiates the workpiece to form a first light spot, the second light beam irradiates the workpiece to form a second light spot, the second light spot is positioned in the first light spot, and the energy of the second light spot and the energy of the first light spot are adjustable;

The first light beam is formed by transmitting unabsorbed pump light in a cladding of the active optical fiber and signal light leaking into the cladding from a fiber core, and the second light beam is formed by transmitting amplified signal light in the fiber core of the active optical fiber and pump light leaking into the fiber core from the cladding;

12. The method of claim 11, wherein the energy profile of the first beam is a flat top profile and the energy profile of the second beam is a gaussian profile.

13. The method as recited in claim 11, further comprising:

the power value of the first light beam is adjusted to adjust the light spot energy distribution of the first light beam irradiated to the workpiece, and/or the power value of the second light beam is adjusted to adjust the light spot energy distribution of the second light beam irradiated to the workpiece.

14. The method as recited in claim 11, further comprising:

And controlling the power value of the first light beam and the power value of the second light beam according to the material of the workpiece.

15. The method as recited in claim 11, further comprising:

the defocus amount of the first light beam is adjusted to adjust the light spot profile and the energy distribution of the first light beam irradiated to the workpiece, or the defocus amount of the second light beam is adjusted to adjust the light spot profile and the energy distribution of the second light beam irradiated to the workpiece.

16. The method of claim 11, wherein the irradiating the laser having at least one of the first beam and the second beam onto the surface of the workpiece comprises:

and transmitting the unabsorbed pump light in the cladding of the optical fiber A of the laser and the signal light leaked into the cladding to form a first light beam, and transmitting the amplified signal light in the fiber core of the optical fiber A and the pump light leaked into the fiber core to form a second light beam.

17. The method of claim 11, wherein the irradiating the laser having at least one of the first beam and the second beam onto the surface of the workpiece comprises:

the optical fiber a of the laser is adapted at the laser processing head by a single fiber joint to direct the first and second beams to a workpiece.

18. The method of claim 11, wherein the wavelength of the first light beam is different from the wavelength of the second light beam.

19. The method of claim 11, wherein the first beam has a center wavelength of 915-1550nm and the second beam has a center wavelength of 1030-2140nm.

20. The method of claim 11, wherein the first beam has a center wavelength of 915nm and the second beam has a center wavelength of 1080nm.