JP5260097B2 - Laser processing equipment - Google Patents

Description

  The present invention relates to a laser processing apparatus that performs desired laser processing by irradiating a workpiece with laser light.

  Recently, fiber laser processing apparatuses that perform desired laser processing by irradiating a workpiece with laser light generated by a fiber laser have been put into practical use. Among them, a fiber laser processing apparatus of a fiber MOPA (Master Oscillator_Power Amplifier) system is also attracting attention.

  As disclosed in Patent Document 1, the fiber MOPA system uses an optical fiber having a core containing a predetermined rare earth element for laser amplification and generates a low-power seed laser beam generated by a seed (seed) laser oscillation unit. Is excited into the core of the optical fiber from one end and propagated to the other end while the core is excited to amplify or convert the seed laser beam into a high-power processing laser beam. / It has features such as high light conversion efficiency and stable beam mode.

In the fiber MOPA system, a semiconductor laser, that is, a laser diode (LD) is mainly used as an excitation light source for optically exciting the active medium of the seed laser oscillation unit. Laser diodes are also often used as excitation light sources for optically exciting the core of the amplification optical fiber.
JP2007-253189

  The conventional fiber laser processing apparatus adopting the fiber MOPA method as described above measures the output of the processing laser beam and controls the laser output measurement value in order to control the output of the processing laser beam to a desired value or waveform. Is fed back to the seed laser oscillator, and the LD drive current supplied to the laser diode for exciting the active medium is variably controlled. The seed laser oscillation unit oscillates and outputs repetitive pulses using, for example, a Q switch. Then, the repetition frequency of the repetition pulse may be changed. When the repetition frequency changes in this manner, the response speed and the degree of freedom of laser output control may be lowered in the method of variably controlling the LD drive current in the seed laser oscillation unit by feedback control.

  In addition, as described above, this type of conventional fiber laser processing apparatus uses a plurality of laser diodes to optically excite the active medium of the seed laser oscillation unit and the core of the optical fiber for amplification. Management or control of the output of the laser diode is performed by the LD current. These laser diodes reduce their individual output due to aging or aging. Therefore, a person (worker, maintenance staff, etc.) measures the LD output of each laser diode using a laser power measuring device as needed or periodically, and adjusts the LD current so as to maintain a desired laser output. . Further, even when the processing laser light output is abnormally lowered and processing defects occur, the cause investigation is performed by measuring the LD output of each part by human work. Such human work is not efficient and accurate in maintenance, and decreases productivity.

  Furthermore, the laser diode for excitation is a consumable item and needs to be replaced before the rated output can be obtained. In this regard, the conventional fiber laser processing apparatus does not have a monitoring function for notifying the life of the excitation laser diode or the time for replacement. For this reason, the life or replacement time of each laser diode is estimated from the accumulated usage time etc. by human work. However, the lifespan of laser diodes varies depending on individual differences and usage environments, and it has not been accurate to estimate the lifespan of each laser diode from the cumulative usage time.

  The present invention has been made in view of the problems of the prior art, and an object of the present invention is to provide a fiber MOPA laser processing apparatus that improves the stability and controllability of the processing laser output.

  In addition, the present invention is equipped with a diagnostic function that eliminates the need for human work on the function or state (performance, safety, deterioration status, etc.) of each unit such as the laser oscillation unit, laser amplification unit, excitation unit, etc. An object of the present invention is to provide a fiber MOPA-type laser processing apparatus that improves performance.

In order to achieve the above object, a laser processing apparatus according to a first aspect of the present invention includes a seed laser oscillation unit that oscillates and outputs a seed laser beam, and a core that includes a predetermined rare earth element. The seed laser beam from one part is inserted into the core from one end, the seed laser beam is amplified and output from the other end, and the amplification optical fiber from one end of the amplification optical fiber A fiber core excitation unit that outputs a core excitation laser beam that is incident on and amplifies the seed laser beam, and a laser that emits a laser beam emitted from the other end of the amplification optical fiber as a processing laser beam and emitting unit, the seed laser output measuring unit that measures an output of the seed laser beam emitted from the seed laser oscillating unit, processing for measuring the output of the processing laser beam A laser output measuring unit, and a processing laser output control unit for controlling the fiber core exciting unit as the processing laser output measured value obtained from the processing laser output measuring unit becomes equal to a preset command value Have.

  In the above apparatus configuration, the output of the seed laser light generated by the seed laser oscillation unit can be monitored by the seed laser output measurement unit, and the stability and controllability of the processing laser output can be improved. For example, as a preferable aspect of the present invention, the seed laser output control unit controls the seed laser oscillation unit so that the seed laser output measurement value matches the preset reference value, thereby stabilizing the processing laser output. Can increase the sex. In a particularly preferred aspect, the seed laser oscillation unit includes a laser resonator including a solid active medium and an active medium excitation unit that excites the active medium. In this case, the seed laser output control unit may control the active medium excitation unit so that the seed laser output measurement value matches the reference value.

  In a preferred aspect, the seed laser oscillation unit generates a Q switch disposed on the same optical path as the active medium in the laser resonator and a laser beam having a Q switch pulse at a predetermined repetition frequency. And a Q switch driving unit for driving the Q switch.

  Preferably, the active medium excitation unit oscillates and outputs an active medium excitation laser beam for exciting the active medium, and a first LD power supply for supplying a first LD drive current to the first laser diode. And have. In this case, the seed laser output control unit controls the first LD drive current through the first LD power source so that the seed laser output measurement value matches the reference value. The first laser diode may be optically coupled to the active medium via the first transmission optical fiber. In this way, the active medium excitation laser beam output from the first laser diode can be reliably incident on the laser oscillator. In addition, since the transmission optical fiber can be arranged in a bent state in the seed laser oscillation unit, it is possible to give flexibility to the elements constituting the seed laser oscillation unit, particularly the arrangement of the first laser diode and the laser resonator. it can.

Further, the Oite the device configuration of the first aspect, the processing laser output measuring unit that measures the output of the processing laser beam, processing laser output measured value obtained from the processing laser output measuring unit in advance A processing laser output control unit that controls the fiber core excitation unit so as to coincide with the set command value is further provided. In this case, preferably, the fiber core pumping unit includes a second laser diode that oscillates and outputs a core pumping laser beam, and a second LD power source that supplies a second LD drive current to the second laser diode. Then, the processing laser output control unit controls the second LD drive current through the second LD power supply so that the processing laser output measurement value matches the command value. According to such a configuration, as described above, the seed laser power output including the seed laser oscillation unit, the seed laser output measurement unit, and the seed laser output control unit is used to stably and accurately reference the output of the seed laser beam. Therefore, the power feedback control for matching or following the output of the processing laser beam with the command value through the fiber core excitation unit can be speeded up more stably.

  The second laser diode may be optically coupled to the active medium via the second transmission optical fiber. By so doing, the core excitation laser beam output from the second laser diode can be reliably incident on the amplification optical fiber. In addition, since the second transmission optical fiber can be arranged in a freely bent state, the arrangement of the fiber core excitation unit and the amplification optical fiber can be given a degree of freedom.

A laser processing apparatus according to a second aspect of the present invention oscillates and outputs a laser resonator including a solid active medium for oscillating and outputting seed laser light, and an active medium excitation laser light for exciting the active medium. A laser diode, an LD power supply for supplying an LD drive current to the laser diode, and a core containing a predetermined rare earth element, and the seed laser light from the laser resonator is put into the core from one end, Amplifying optical fiber for amplifying the seed laser light to be output from the other end, and for core excitation for amplifying the seed laser light by entering the optical fiber for amplification from one end of the optical fiber for amplification A fiber core excitation unit that outputs laser light; a laser emission unit that emits laser light emitted from the other end of the amplification optical fiber as processing laser light; and the laser An active medium exciting laser output measuring unit for measuring an output of said active medium exciting laser light emitted from the diode, sets the active medium exciting active medium excitation laser output measured value obtained from the laser output measuring unit in advance And an active medium excitation laser output controller for controlling the LD power supply so as not to exceed the set upper limit value .

In the above apparatus configuration, the output of the laser diode for exciting the active medium of the laser resonator is monitored by the seed laser output measuring unit, and the laser resonator or a mechanism for exciting the laser resonator (laser diode, LD power supply, etc.) Protection or stable performance can be maintained. Furthermore , the excitation laser output measurement value obtained from the active medium excitation laser output measurement unit is fed back to the excitation laser output control unit, so that the excitation laser output measurement value does not exceed the preset upper limit value. The laser output control unit controls the LD power source. As a result, it is possible to prevent the active medium of the laser resonator from being damaged by excessive excitation energy.

  Further, as a preferred embodiment, an LD life notification unit for notifying the life of the laser diode or the replacement timing may be provided based on the excitation laser output measurement value obtained from the excitation laser output measurement unit.

  In a preferred embodiment, the seed laser output measurement unit that measures the output of the seed laser light emitted from the laser resonator, the excitation laser output measurement value obtained from the excitation laser output measurement unit, and the seed laser A diagnostic unit for diagnosing whether the function of at least one of the LD power supply, the laser diode, and the laser resonator is normal or abnormal based on the seed laser output measurement value obtained from the output measurement unit is further provided. It is done. The laser diode may be optically coupled to the active medium of the laser resonator via a transmission optical fiber. In this case, the diagnosis unit can also diagnose the normality / abnormality of the transmission optical fiber.

  A laser processing apparatus according to a third aspect of the present invention includes a seed laser oscillation unit that oscillates and outputs a seed laser beam, and a core that includes a predetermined rare earth element, and the seed laser beam from the seed laser oscillation unit is one end. An optical fiber for amplification that enters the core and amplifies the seed laser light to be emitted from the other end, and laser emission that emits laser light emitted from the other end of the optical fiber for amplification as processing laser light A laser diode that oscillates and outputs a core excitation laser beam for exciting the core in order to amplify the seed laser light in the core of the amplification optical fiber, and an LD drive current to the laser diode And a core excitation laser output measuring unit for measuring the output of the core excitation laser light emitted from the laser diode.

  In the above apparatus configuration, the output of the laser diode for exciting the core of the amplification optical fiber is monitored by the excitation laser output measuring unit, and the amplification optical fiber, the laser resonator or a mechanism for exciting the same (laser diode) , LD power supply, etc.) or stable performance can be maintained. For example, as a preferred embodiment, the excitation laser output measurement value obtained from the excitation laser output measurement unit is fed back to the excitation laser output control unit, and the excitation laser output measurement value does not exceed a preset upper limit value. As described above, the pumping laser output control unit may control the LD power source, thereby preventing the active medium of the laser resonator from being damaged by excessive pumping energy.

  Further, as a preferred embodiment, an LD life notification unit for notifying the life of the laser diode or the replacement timing may be provided based on the excitation laser output measurement value obtained from the excitation laser output measurement unit.

  In a preferred embodiment, the processing laser output measurement unit that measures the output of the processing laser beam, the excitation laser output measurement value obtained from the excitation laser output measurement unit, and the processing laser output measurement unit A diagnostic unit is further provided for diagnosing whether the function of at least one of the LD power source, the laser diode, and the amplification optical fiber is normal or abnormal based on the obtained processing laser output measurement value. The laser diode may be optically coupled to the amplification optical fiber via a transmission optical fiber. In this case, the diagnosis unit can also diagnose the normality / abnormality of the transmission optical fiber.

  According to the laser processing apparatus of the present invention, the stability and controllability of the processing laser output in the fiber MOPA system can be improved by the configuration and operation as described above. Furthermore, it is possible to automatically diagnose the function or state (performance, safety, deterioration status, etc.) of each part such as the laser oscillation part, laser amplification part, excitation part, etc. on the device side without requiring human work. Yes, maintainability and productivity can be improved.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

  In FIG. 1, the structure of the laser processing apparatus in one Embodiment of this invention is shown. This laser processing apparatus is configured as a fiber MOPA type fiber laser processing apparatus, and includes an amplification optical fiber (hereinafter referred to as “amplifier fiber”) 10, a seed laser oscillation unit 12, a fiber core excitation unit 14, and a laser. An emission unit 16, a processing table 18, a control unit 20, laser output measurement units 22, 24, LD output measurement units 26, 28, and the like are provided.

  Although not shown, the amplifier fiber 10 has a core made of, for example, quartz doped with ions of a rare earth element such as ytterbium (Yb), and a clad made of, for example, quartz surrounding the core coaxially. The seed laser beam SB is a propagation optical path, and the cladding is a propagation optical path of a core excitation laser beam FB described later. The length of the amplifier fiber 10 may be arbitrarily selected, for example, several meters.

  The seed laser oscillation unit 12 includes a laser resonator 30 that oscillates and outputs a Y switch laser beam (wavelength: 1064 nm) of a Q switch pulse. In this laser resonator 30, a YAG rod (active medium) 36 and a Q switch 38 are arranged in a linear array between a pair of optically opposed resonator mirrors 32 and 34. The Q switch 38 is composed of an acousto-optic switch, for example, and is switched at a predetermined frequency by the Q switch driver 40 under the control of the control unit 20.

The seed laser oscillating unit 12 includes an end face excitation type electro-optic excitation unit 42 for exciting the YAG rod 36. The electro-optic excitation unit 42 includes a fiber coupling LD 44 and an LD power source 46. The fiber coupling LD 44 is injected with an LD drive current I ₁ from the LD power source 46 under the control of the control unit 20 and outputs, for example, a YAG rod excitation laser beam EB having a wavelength of 808 nm in continuous oscillation. The YAG rod excitation laser beam EB generated by the fiber coupling LD 44 is transmitted through a converging lens (not shown) to one end face (incident end face) of a transmission optical fiber (hereinafter referred to as “transmission fiber”) 48. ), Propagates through the transmission fiber 48, exits radially from the other end face (exit end face), passes through the collimating lens and the converging lens (not shown), enters the laser resonator 30, and is totally reflected. The mirror 32 is transmitted from the back side and is incident on one end surface of the YAG rod 36 to pump the YAG rod 36 continuously or continuously. When the Q switch 38 is switched by accumulating energy in the laser resonator 30 by this continuous pumping (generating an inversion distribution), the giant pulse oscillation occurs, and the YAG laser beam of the Q switch pulse having a very high peak power is generated. Is output from the output mirror 34 of the laser resonator 30. The transmission fiber 48 may be, for example, an SI (step index) type fiber.

In this embodiment, in order to measure the power (LD output) of the YAG rod excitation laser beam EB generated by the fiber coupling LD 44 in association with the electro-optic excitation unit 42, the mirror 50 and the LD output measurement unit 26 are measured. Is provided. The mirror 50 reflects a small part (for example, 1%) of the YAG rod excitation laser beam EB before the incident end face of the transmission fiber 48. The LD output measurement unit 26 includes a photoelectric conversion element and a measurement circuit, receives the reflected light _MEB from the mirror 50 and converts it into an electrical signal, and measures a laser output (LD output) value of the laser beam EB by signal processing. Ask for. The LD output measurement value obtained by the LD output measurement unit 26 is sent to the control unit 20 for monitoring described later.

  The Y switch laser beam of the Q switch pulse oscillated and output from the seed laser oscillator 12 as described above is introduced into the amplifier fiber 10 as the seed laser beam SB. Although not shown, a beam expander and a converging lens of the incident optical system are disposed between the laser exit of the seed laser oscillation unit 12 and the incident end face 10a of the amplifier fiber 10. The seed laser beam SB of the Q switch pulse from the seed laser oscillating unit 12 expands the beam diameter by the beam expander, passes through the converging lens, and enters the incident end face 10a of the amplifier fiber 10 (more precisely, the incident end face of the core). ) Is focused and incident.

  In this fiber laser processing apparatus, as will be described later, the seed laser beam SB is amplified in the amplifier fiber 10 to generate the processing laser beam MB for the workpiece W, so that the laser output (effective) of the seed laser beam SB is effective. Value) can be set to a very low value (for example, about 1 W). In connection with this, the seed laser oscillation unit 12 is configured as a small output solid-state laser. A fiber coupling LD can be used. In this way, the seed laser oscillation unit 12 is a low-power YAG laser and employs an end face excitation method, so that the single mode seed laser beam SB can be easily obtained.

In this embodiment, a mirror 52 and a laser output measurement unit 24 are provided to measure the power or laser output of the seed laser beam SB oscillated and output from the seed laser oscillation unit 12. The mirror 52 transmits most of the seed laser beam SB emitted from the seed laser oscillation unit 12 and reflects a small part (for example, 1%). The LD output measurement unit 24 includes a photoelectric conversion element and a measurement circuit, receives the reflected light _MSB from the mirror 52 and converts it into an electrical signal, and converts the laser output measurement value of the seed laser beam SB by signal processing. Ask. The seed laser output measurement value obtained by the LD output measurement unit 26 is sent to the control unit 20 for laser output control and monitoring described later.

The fiber core excitation unit 14 includes a fiber coupling LD 54, an LD power source 56, a transmission fiber 58, and the like. The fiber coupling LD 54 is injected with an LD drive current I ₂ from the LD power source 56 under the control of the control unit 20 and outputs, for example, a laser beam FB for core excitation having a wavelength of 980 nm in continuous oscillation. The fiber coupling LD 54 is a relatively large array in which a large number of LD elements are arranged one-dimensionally or two-dimensionally so that the core of the amplifier fiber 10 can be excited with a relatively high power of about 30 to 80 W, for example. It is preferable to adopt a structure or a stack structure.

  The core excitation laser beam FB emitted from the fiber coupling LD 54 is condensed and incident on one end face (incident end face) of the transmission fiber 58 through a converging lens (not shown). The transmission fiber 58 is made of, for example, an SI fiber, and transmits the core excitation laser beam FB taken from the LD 54 to the vicinity of the incident surface 10 a of the amplifier fiber 10.

  The other end surface (outgoing end surface) of the transmission fiber 58 is optically coupled to the incident surface 10 a of the amplifier fiber 10 via a collimating lens, a converging lens (not shown), and a folding mirror 60. The folding mirror 60 is disposed at a predetermined angle or orientation at a position where the optical axis on the output side of the transmission fiber 58 and the optical axis on the incident side of the amplifier fiber 10 intersect, and with respect to the wavelength of the core excitation light FB. The reflective film and the non-reflective film with respect to the wavelength of the processing laser beam MB are coated. The core excitation laser beam FB emitted from the emission end face of the transmission fiber 58 is collimated into parallel light by the collimating lens, condensed by the converging lens, and the optical fiber is bent at a right angle by the folding mirror 60 to be amplified by the amplifier fiber 10. Is incident on the incident end face 10a.

In this embodiment, a mirror 62 and an LD output measurement unit 28 are attached to the fiber core excitation unit 14 to measure the power (LD output) of the core excitation laser light FB generated by the fiber coupling LD 54. Is provided. The mirror 62 reflects a small part (for example, 1%) of the core excitation laser beam FB in front of the incident end face of the transmission fiber 58. The LD output measurement unit 28 has a photoelectric conversion element and a measurement circuit, receives the reflected light _MFB from the mirror 62 and converts it into an electrical signal, and converts the laser output measurement value of the core excitation laser beam FB by signal processing. Ask. The laser output measurement value obtained by the LD output measurement unit 28 is sent to the control unit 20 for monitoring described later.

  In the amplifier fiber 10, as described above, the incident end face 10 a has a Q-switched pulse seed laser beam SB from the seed laser oscillation unit 12 and a continuous oscillation core excitation laser beam FB from the fiber core excitation unit 14. Is incident. As will be described later, the core excitation laser beam FB can be incident on the opposite end face 10b of the amplifier fiber 10.

  In the amplifier fiber 10, the seed laser beam SB propagates in the core in the axial direction toward the other end face of the fiber (outgoing end face 10b) while being confined by total reflection at the interface between the core and the clad. On the other hand, the core excitation laser beam FB propagates in the axial direction in the amplifier fiber 10 while being confined by the total reflection at the cladding outer peripheral interface, and crosses the core many times during the propagation, so that the Yb ions in the core are absorbed. Photoexcitation. Thus, the seed laser beam SB is amplified until it has a laser output of a command value (for example, 30 W) in the active core while propagating through the amplifier fiber 10, and is amplified as a high-power processing laser beam MB. 10 exits from the exit end face 10b. This processing laser beam MB is a YAG laser beam having the same wavelength (1064 nm) as that of the seed laser beam SB.

  The amplifier fiber 10 confines and amplifies the seed laser beam SB in an elongated core having a diameter of about 10 μm and a length of about several meters, so that the processing laser beam MB having a small beam diameter and a small beam divergence angle can be taken out. it can. In addition, since the core excitation laser beam FB incident on the incident end face 10a of the amplifier fiber 10 propagates through the long optical path in the amplifier fiber 10 and exhausts the excitation energy many times, the efficiency is very high. The low output (for example, 1 W) seed laser beam SB can be amplified to the high output (30 W) processing laser beam MB.

  In addition, since the core of the amplifier fiber 10 does not cause a thermal lens effect, the beam mode is very stable and no special cooling is required. Accordingly, it is possible to amplify the single mode of the seed laser beam SB while keeping it stable in the amplifier fiber 10 to obtain the single mode processing laser beam MB.

  It should be noted that the core excitation laser beam FB exits from the output end face 10b of the amplifier fiber 10 in a state where the laser energy is almost used up in the amplifier fiber 10 and the light intensity is considerably attenuated. A folding mirror (not shown) for removing the used light FB passing through the amplifier fiber 10 to the side may be arranged.

  As described above, the Q-switched pulse processing laser beam MB that has emerged on the optical axis from the output end face 10 b of the amplifier fiber 10 passes straight through the folding mirror 64, and changes its optical path by, for example, the vent mirror 66 to the output unit 16. enter.

  The emission unit 16 accommodates a galvanometer scanner, an fθ lens, and the like. The galvanometer scanner has a pair of movable mirrors capable of swinging in two orthogonal directions. Both movable mirrors are synchronized with the Q switching operation of the seed laser oscillation unit 12 under the control of the control unit 20. Is controlled to a predetermined angle so that the processing laser beam MB of the Q switch pulse from the amplifier fiber 10 is condensed and irradiated to a desired position on the surface of the workpiece W on the processing table 18. The marking process performed on the surface of the workpiece W typically draws characters, figures, and the like, but surface removal processes such as trimming are also possible.

In this embodiment, the folding mirror 64 and the laser output measuring unit 22 are provided in order to measure the laser output of the laser beam MB for processing the Q switch pulse. The mirror 64 transmits most of the processing laser light MB emitted from the amplifier fiber 10 and reflects a small part (for example, 1%) thereof. Laser output measurement unit 22 has a photoelectric conversion element and the measurement circuit, and converted into an electric signal by receiving the reflected light M _MB from the mirror 64, the laser output measured value of the processing laser beam MB by the signal processing Ask for. The measured laser output measurement value obtained by the LD output measurement unit 22 is sent to the control unit 20 for laser output control and monitoring described later.

  The control unit 20 may be composed of a microcomputer, performs data processing such as input / setting / calculation to control the entire apparatus or each unit, and displays an input unit (not shown) such as a keyboard and a liquid crystal display. Data or information is exchanged with a person (worker, maintenance worker, etc.) via a man-machine interface comprising the unit 68.

  As described above, this fiber laser processing apparatus includes not only the laser output measuring unit 22 for measuring the laser output of the processing laser beam MB but also the laser output measuring unit for measuring the laser output of the seed laser beam SB. 24, an LD output measurement unit 26 for measuring the laser output (LD output) of the YAG rod excitation laser beam EB, and an LD output measurement unit 28 for measuring the laser output (LD output) of the core excitation laser beam FB. It also has. The control unit 20 applies the laser output (or LD output) measurement values obtained by these four laser output (or LD output) measuring units 22, 24, 26, and 28 to a predetermined laser output control or monitoring program. Predetermined calculation processing is performed, and operation of each unit is controlled and necessary monitor information is displayed and output according to the calculation result.

  Hereinafter, various functions using the laser output (or LD output) measuring units 22, 24, 26, and 28 in this fiber laser processing apparatus will be described.

First, the fiber laser processing apparatus has a function of holding the laser output of the seed laser beam SB at a reference value using the laser output measuring unit 24. More specifically, the laser output of the seed laser beam SB emitted from the seed laser oscillation unit 12 is measured by the laser output measurement unit 24, and the laser output measurement value is fed back to the control unit 20. The control unit 20 sets a laser output reference value corresponding to the repetition frequency of the seed laser beam SB of the Q switch pulse oscillated and output from the laser resonator 30, and the laser output measurement value from the laser output measurement unit 24. Is controlled to the current value of the LD drive current I ₁ supplied to the fiber coupling LD 44 through the LD power source 46 so that it matches the laser output reference value.

That is, by changing the current value of the LD drive current I ₁ , the output of the YAG rod excitation laser beam EB generated by the fiber coupling LD 44 is changed, and consequently the inversion distribution generation speed in the laser resonator 30 is changed. In addition, the output (effective value or average value) of the seed laser beam SB can be varied. Here, since the output of the seed laser beam SB mainly depends on the repetition frequency of the Q switch pulse, the variable adjustment of the inversion distribution generation speed is limited to the fine adjustment. However, the power feedback control mechanism using the laser output measuring unit 24 as described above is indispensable for stably and accurately matching the output of the seed laser beam SB with the reference value. For example, the output of the seed laser beam SB may fluctuate due to a change in the ambient temperature of the laser resonator, and the laser output measuring unit 24 is used to suppress dynamic laser output fluctuations based on such environmental changes and disturbances. The power feedback control mechanism using is very effective.

Secondly, this fiber laser processing apparatus has a function of making the laser output of the processing laser beam MB coincide with the command value by using the laser output measuring unit 22. More specifically, the laser output of the processing laser beam MB emitted from the amplifier fiber 10 is measured by the laser output measuring unit 22, and the measured laser output value is fed back to the control unit 20. The control unit 20 sets a laser output command value for the processing laser beam MB as one of the laser processing conditions input from the input unit, and the laser output measurement value from the laser output measurement unit 22 is the laser output command value. The current value of the LD drive current I ₂ supplied to the fiber coupling LD 54 is controlled through the LD power source 56 so as to match the above.

In this case, by changing the current value of the LD drive current I ₂ , the output of the core excitation laser beam FB generated by the fiber coupling LD 54 is changed, and as a result, the output of the seed laser beam SB in the amplifier fiber 10. The degree of amplification (especially peak power) (amplification factor) can be varied, and the output of the processing laser beam MB can be varied. As described above, the method of changing the output of the processing laser beam MB by changing the peak power is excellent in the response of the laser output control and can improve the laser processing capability. In addition, since the output of the seed laser beam SB is made to coincide with the reference value stably and accurately by the seed laser power feedback control mechanism as described above, the output of the processing laser beam MB is set to the command value through the fiber core excitation unit 14. The power feedback control for matching or following can be speeded up more stably.

  Third, the fiber laser processing apparatus has a function of protecting the optical components in the seed laser oscillation unit 12, particularly the YAG rod (active medium) 36 in the laser resonator 30, using the LD output measurement unit 26. Yes. More specifically, the output of the YAG rod excitation laser beam EB generated by the fiber coupling LD 54 is measured by the laser output measuring unit 26, and the measured laser output value is given to the control unit 20. The control unit 20 sets the maximum allowable value of the LD output that does not damage the YAG rod 36, and monitors so that the output of the YAG rod excitation laser beam EB does not exceed the maximum allowable value. For example, when the output of the laser beam EB for YAG rod excitation rises and exceeds the maximum allowable value in the seed laser power feedback control as described above, the LD power source 46 is set so as not to increase further. Control.

Fourthly, this fiber laser processing apparatus has a function of notifying the service life or replacement time of the fiber coupling LD 44 using the LD output measuring unit 26. More specifically, when the control unit 20 variably controls the LD drive current I ₁ through the LD power supply 46, the control unit 20 associates the LD output measurement value obtained by the LD output measurement unit 26 with the LD drive current command value, and performs linear interpolation. Etc. is used to obtain the LD drive current-LD output characteristics as shown in FIG. The slope K of the LD drive current-LD output characteristic gradually decreases as K ₁ → K ₂ →→ K ₃ ... As the fiber coupling LD 44 deteriorates with time. Therefore, the slope K _S immediately before the end of the life of the fiber coupling LD 44 is set as a monitoring value based on the experience value or the like, and when the slope K of the LD driving current-LD output characteristic is lowered to the monitoring value K _S , At this point, the control unit 20 displays (notifies) that the fiber coupling LD 44 is near the end of its life, that is, that it is time to replace the parts. According to such an LD life notification function, even if there is an individual difference or a use environment difference in the fiber coupling LD 44, it is possible to replace the LD parts at an appropriate time.

Fifth, the fiber laser processing apparatus uses at least one of the fiber coupling LD 44, the LD power source 46, and the laser resonator 30 in the seed laser oscillation unit 12 using the laser output measurement unit 24 and the LD output measurement unit 26. It has a function of diagnosing whether the function is normal or abnormal. More specifically, when the seed laser measurement value obtained from the laser output measurement unit 24 is abnormally lowered, or when the seed laser power feedback control as described above is not performed, the control unit 20 The LD output measurement value obtained by the LD output measurement unit 26 is inspected while variably controlling the current value of the LD drive current I ₁ through the LD power source 46. As a result of the inspection, if the LD output measurement value is also abnormally lowered or the response is not good, it is determined that the fiber coupling LD 44 or the LD power source 46 has deteriorated or failed. When the LD output measurement value is normal or within an allowable range, it is determined that there is a defect or a defect somewhere in the transmission fiber 48 or the laser resonator 30. Then, the determination (diagnosis) result is displayed and output through the display unit 68.

  Sixth, this fiber laser processing apparatus has a function of protecting the core of the amplifier fiber 10 using the LD output measuring unit 28. More specifically, the output of the core excitation laser beam FB generated by the fiber coupling LD 54 is measured by the laser output measuring unit 28, and the measured laser output value is given to the control unit 20. The control unit 20 sets a maximum allowable value of the LD output that does not damage the core of the amplifier fiber 10 and monitors so that the output of the core excitation laser beam FB does not exceed the maximum allowable value. For example, when the output of the core excitation laser beam FB rises and exceeds the maximum allowable value in the laser power feedback control for processing as described above, the LD power source 56 is set so as not to increase further. Control.

Seventh, this fiber laser processing apparatus has a function of notifying the service life or replacement time of the fiber coupling LD 54 using the LD output measuring unit 28. More specifically, when the control unit 20 variably controls the LD drive current I ₂ through the LD power source 56, the control unit 20 associates the LD output measurement value obtained by the LD output measurement unit 28 with the LD drive current command value, and performs linear interpolation. Etc. is used to obtain the LD drive current-LD output characteristics as shown in FIG. Then, the notification can be made when the life of the fiber coupling LD 54 is approaching in the same manner as that for the fiber coupling LD 44 in the electro-optic excitation unit 42.

Finally, this fiber laser processing apparatus uses the laser output measuring unit 22 and the LD output measuring unit 28 to at least one of the fiber coupling LD 54, the LD power source 56, the transmission fiber 58, and the amplifier fiber 10 in the seed laser oscillation unit 120. Has a function of diagnosing whether the function is normal or abnormal. More specifically, when the processing laser measurement value obtained from the laser output measuring unit 22 is abnormally decreased, or when the power feedback control is performed on the processing laser as described above, the reference value is not easily reached. The control unit 20 inspects the LD output measurement value obtained by the LD output measurement unit 26 while variably controlling the current value of the LD drive current I ₂ through the LD power source 56. As a result of the inspection, when the LD output measurement value is also abnormally lowered or the response is not good, it is determined that the fiber coupling LD 54 or the LD power source 56 has deteriorated or failed. When the LD output measurement value is normal or within an allowable range, it is determined that there is a defect or defect somewhere in the transmission fiber 58 or the amplifier fiber 10. Then, the determination (diagnosis) result is displayed and output through the display unit 68.

  As mentioned above, although preferred embodiment of this invention was described, embodiment mentioned above does not limit this invention. Those skilled in the art can make various modifications and changes in specific embodiments without departing from the technical idea and technical scope of the present invention.

For example, although the above-described embodiment relates to a laser processing apparatus of Q switching system, the present invention is not limited to the Q switching system. For example, in the laser resonator 30 of the seed laser oscillation unit 10, the Q switch 28 is omitted, and the LD drive current I ₁ supplied to the fiber coupling LD 44 by the LD power source 46 under the control of the control unit 20 is an arbitrary pulse waveform. Thus, the seed laser oscillation unit 10 can generate the pulse laser beam as the seed laser beam SB, and the pulse laser beam can be extracted from the amplifier fiber 10 as the laser beam MB for laser welding, for example.

  Further, the laser emitting unit 16 may be configured as a fixed emission type (non-scanning type) including a collimating lens, a shutter, and a converging lens (not shown) instead of the scanning mechanism including the galvanometer scanner and the fθ lens. It is. Furthermore, a configuration in which an XY table mechanism, a lifting mechanism, a θ rotation mechanism, and the like are provided on the processing table 18 is also possible.

  In the above-described embodiment, the YAG laser is used for the seed laser oscillation unit 12. However, other types or types of lasers can be used, and the wavelengths of the seed laser light and the excitation laser light can be arbitrarily selected. It is also possible to omit the transmission fibers 48 and 58 and replace the fiber coupling LDs 44 and 54 with ordinary LDs or LD arrays.

  Further, in the embodiment of FIG. 1, the excitation laser beam FB emitted from the fiber core excitation unit 14 is configured to enter the fiber from the end face 10a of the amplifier fiber 10 together with the seed laser beam SB. Instead, the excitation laser beam FB may be incident on the amplifier fiber 10 from the opposite end face 10b.

It is a block diagram which shows the structure of the fiber laser processing apparatus of the fiber MOPA system in one Embodiment of this invention. It is a figure which shows an example of the method of determining the lifetime of fiber coupling LD in embodiment.

Explanation of symbols

10 Amplifying optical fiber (amplifier fiber)
DESCRIPTION OF SYMBOLS 12 Seed laser oscillation part 14 Fiber core excitation part 16 Output unit 20 Control part 22,24 Laser output measurement part 26,28 LD output measurement part 30 Laser resonator 42 Electro-optical excitation part 44 Fiber coupling LD
46 LD power supply 48 Optical fiber for transmission (transmission fiber)
54 Fiber coupling LD
56 LD power supply 58 Optical fiber for transmission (transmission fiber)
68 Display

Claims (19)

A seed laser oscillation unit that oscillates and outputs seed laser light;
An amplification optical fiber having a core containing a predetermined rare earth element, putting the seed laser light from the seed laser oscillation unit into the core from one end, amplifying the seed laser light, and emitting from the other end; ,
A fiber core pumping unit that outputs a core pumping laser beam that enters the amplification optical fiber from one end of the amplification optical fiber and amplifies the seed laser beam;
A laser emitting portion for emitting laser light emitted from the other end of the amplification optical fiber as processing laser light;
A seed laser output measuring unit for measuring the output of the seed laser light emitted from the seed laser oscillation unit ;
A laser output measurement unit for processing that measures the output of the laser beam for processing;
A laser processing apparatus comprising: a processing laser output control unit that controls the fiber core excitation unit so that a processing laser output measurement value obtained from the processing laser output measurement unit matches a preset command value .   The laser processing apparatus according to claim 1, further comprising: a seed laser output control unit that controls the seed laser oscillation unit so that a seed laser output measurement value obtained from the seed laser output measurement unit matches a preset reference value. . The seed laser oscillation unit includes a laser resonator including a solid active medium, and an active medium excitation unit that excites the active medium,
The seed laser output control unit controls the active medium excitation unit so that the seed laser output measurement value matches the reference value ;
The laser processing apparatus according to claim 2. The seed laser oscillation unit is
A Q switch disposed on the same optical path as the active medium in the laser resonator;
The laser beam of Q-switched pulse and a Q-switch driving unit that drives the Q-switch to produce a predetermined repetition frequency, laser machining apparatus according to claim 3. The active medium excitation unit includes a first laser diode that oscillates and outputs an active medium excitation laser beam for exciting the active medium, and a first LD power source that supplies a first LD drive current to the first laser diode. And
The seed laser output control unit controls the first LD driving current through the first LD power source so that the seed laser output measurement value matches the reference value ;
The laser processing apparatus according to claim 3 or 4. The first laser diode is optically coupled to the active medium through a first transmission optical fiber, a laser processing apparatus according to claim 5. The fiber core pumping unit includes a second laser diode that oscillates and outputs the core pumping laser light, and a second LD power source that supplies a second LD drive current to the second laser diode,
The processing laser output control unit controls the second LD drive current through the second LD power source so that the processing laser output measurement value matches the command value .
The laser processing apparatus as described in any one of Claims 1-6 . The laser processing apparatus according to claim 7 , wherein the second laser diode is optically coupled to a core of the amplification optical fiber via a second transmission optical fiber. A laser resonator including a solid active medium for oscillating and outputting seed laser light;
A laser diode that oscillates and outputs an active medium excitation laser beam for exciting the active medium;
An LD power supply for supplying an LD drive current to the laser diode;
An optical fiber for amplification that has a core containing a predetermined rare earth element, puts the seed laser light from the laser resonator into the core from one end, amplifies the seed laser light, and emits the seed laser light from the other end;
A fiber core pumping unit that outputs a core pumping laser beam that enters the amplification optical fiber from one end of the amplification optical fiber and amplifies the seed laser beam;
A laser emitting portion for emitting laser light emitted from the other end of the amplification optical fiber as processing laser light;
An active medium excitation laser output measuring unit for measuring an output of the active medium excitation laser light emitted from the laser diode ;
An active medium excitation laser output control unit for controlling the LD power supply so that an active medium excitation laser output measurement value obtained from the active medium excitation laser output measurement unit does not exceed a preset upper limit value; Laser processing equipment. 10. The laser processing apparatus according to claim 9 , further comprising: an LD life notification unit that notifies the life or replacement time of the laser diode based on an active medium excitation laser output measurement value obtained from the active medium excitation laser output measurement unit. . A seed laser output measuring unit for measuring the output of the seed laser light emitted from the laser resonator;
Based on the measured laser output measurement value for excitation of the active medium obtained from the laser output measurement unit for excitation of the active medium and the seed laser output measurement value obtained from the seed laser output measurement unit, the LD power source, the laser diode, and the laser The laser processing apparatus according to claim 9 or 10 , further comprising: a diagnosis unit that diagnoses whether at least one of the resonators has a normal function or an abnormal function. It said laser diode via an optical fiber for transmission is optically coupled to the active medium within the laser cavity, the laser machining apparatus according to any one of claims 9-11. Based on the laser output measurement value for excitation of the active medium obtained from the laser output measurement unit for excitation of the active medium and the seed laser output measurement value obtained from the seed laser output measurement unit, the diagnostic unit, the LD power source, The laser processing apparatus according to claim 12 , which diagnoses whether at least one of a laser diode, the transmission optical fiber, and the laser resonator has a normal function or an abnormal function. A seed laser oscillation unit that oscillates and outputs seed laser light;
An amplification optical fiber having a core containing a predetermined rare earth element, putting the seed laser light from the seed laser oscillation unit into the core from one end, amplifying the seed laser light, and emitting from the other end; ,
A laser emitting portion for emitting laser light emitted from the other end of the amplification optical fiber as processing laser light;
A laser diode that oscillates and outputs a core excitation laser beam for exciting the core in order to amplify the seed laser light in the core of the amplification optical fiber;
An LD power supply for supplying an LD drive current to the laser diode;
A laser processing apparatus comprising: a core excitation laser output measurement unit that measures an output of the core excitation laser light emitted from the laser diode. As the core excitation laser output measured value obtained from the core excitation laser output measuring unit does not exceed a preset upper limit value, to claim 14 having a core excitation laser output controller for controlling the LD power source The laser processing apparatus as described. 16. The laser according to claim 14 , further comprising an LD life notification unit that notifies the life or replacement time of the laser diode based on a measured value of the laser output for core excitation obtained from the laser output measurement unit for core excitation. Processing equipment. A laser output measurement unit for processing that measures the output of the laser beam for processing;
Based on the core excitation laser output measurement value obtained from the core excitation laser output measurement unit and the processing laser output measurement value obtained from the processing laser output measurement unit, the LD power source, the laser diode, and the amplification The laser processing apparatus according to any one of claims 14 to 16 , further comprising: a diagnosis unit that diagnoses whether at least one of the optical fibers for use is normal or abnormal. The laser diode is optically coupled to the amplifying optical fiber through the optical fiber for transmission, the laser processing apparatus according to any one of claims 14-17. Based on the core excitation laser output measurement value obtained from the core excitation laser output measurement unit and the seed laser output measurement value obtained from the seed laser output measurement unit, the diagnosis unit performs the LD power supply, the laser diode 19. The laser processing apparatus according to claim 18 , which diagnoses whether at least one of the transmission optical fiber and the amplification optical fiber laser has a normal function or an abnormal function.

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