JP2016081994A - Direct diode laser oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a direct diode laser oscillator which allows for appropriate temperature control for an optical element on which a multiwavelength laser beam impinges, while stabilizing the output of the multiwavelength laser beam.SOLUTION: A direct diode laser oscillator includes a plurality of laser diodes, each outputting a multiwavelength laser beam, an optical element on which the multiwavelength laser beams, outputted from the plurality of laser diodes, impinge, a LD cooler for cooling at least one of the plurality of laser diodes, and an optical element cooler for cooling the optical element by a separate line from the LD cooler.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a direct diode laser oscillator.

2. Description of the Related Art Conventionally, as a laser processing apparatus for processing a sheet metal, an apparatus using a carbon dioxide (CO ₂ ) laser oscillator, a YAG laser oscillator, or a fiber laser oscillator as a laser light source is known. The fiber laser oscillator has advantages such as better light quality and extremely high oscillation efficiency than the YAG laser oscillator. For this reason, a fiber laser processing apparatus using a fiber laser oscillator is used for industrial purposes, particularly for sheet metal processing (cutting or welding).

  In recent years, DDL processing apparatuses using a direct diode laser (DDL) oscillator as a laser light source have been developed. In a DDL processing apparatus, a plurality of optical elements such as diffraction gratings are arranged in a resonator, and multiple-wavelength laser beams from a plurality of laser diodes (LD) are used by using the optical elements. Superimpose and transmit to the processing head using a transmission fiber. Then, the laser light emitted from the end face of the transmission fiber is condensed and irradiated on the workpiece by a collimator lens and a condenser lens.

  Incidentally, a conventional apparatus using an LD is provided with a cooling device for cooling the LD (see Patent Document 1).

JP 2002-314011 A

  However, in the DDL processing apparatus, when the LD cooling device is diverted to cool the optical element such as a diffraction grating disposed in the resonator, the temperature of the optical element cannot be sufficiently controlled. For this reason, the optical conditions for resonance etc. are affected, and there is a problem that the stability of the laser output cannot be obtained.

  The present invention has been made in view of the above problems, and its purpose is to sufficiently control the temperature of an optical element that receives multi-wavelength laser light, and to stabilize the output of the multi-wavelength laser light. It is an object of the present invention to provide a direct diode laser oscillator that can be realized.

  According to one aspect of the present invention, among a plurality of laser diodes that respectively output multi-wavelength laser light, an optical element that receives multi-wavelength laser light output by a plurality of laser diodes, and a plurality of laser diodes There is provided a direct diode laser oscillator comprising: an LD cooling device that cools at least one of the optical element; and an optical element cooling device that cools the optical element in a separate system from the LD cooling device.

  According to the present invention, there is provided a direct diode laser oscillator that can appropriately control the temperature of an optical element that receives multi-wavelength laser light and can stabilize the output of the multi-wavelength laser light. can do.

It is a perspective view which shows an example of the DDL processing apparatus which concerns on embodiment of this invention. FIG. 2A is a front view showing an example of the DDL oscillator according to the embodiment of the present invention. FIG. 2B is a side view showing an example of the DDL oscillator according to the embodiment of the present invention. It is the schematic which shows an example of the DDL module which concerns on embodiment of this invention. It is the schematic which shows the example of arrangement | positioning of the cooling device provided in the DDL oscillator which concerns on embodiment of this invention. It is the schematic which shows the example of arrangement | positioning of the cooling device provided in the DDL oscillator which concerns on other embodiment of this invention.

  Embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

  With reference to FIG. 1, an overall configuration of a direct diode laser (hereinafter referred to as “DDL”) processing apparatus according to an embodiment of the present invention will be described. As shown in FIG. 1, a DDL processing apparatus according to an embodiment of the present invention includes a laser oscillator 11 that oscillates multi-wavelength laser light LB, and a transmission fiber (process) that transmits the laser light LB oscillated by the laser oscillator 11. Fiber) 12 and a laser beam machine 13 for condensing the laser beam LB transmitted by the transmission fiber 12 to a high energy density and irradiating the workpiece (workpiece) W. The DDL processing apparatus according to the embodiment of the present invention further includes an LD cooling device 70 and optical element cooling devices 71, 72, 73 connected to the laser oscillator 11.

  The laser processing machine 13 includes a collimator unit 14 that converts the laser light LB emitted from the transmission fiber 12 into substantially parallel light by the collimator lens 15, and the laser light LB converted to substantially parallel light in the X-axis and Y-axis directions. A dispersive element (diffraction grating) 16 that diffracts downward in the Z-axis direction perpendicular to the surface, and a processing head 17 that condenses the laser light LB diffracted by the dispersive element 16 by a condensing lens 18. Although not shown in FIG. 1, a lens driving unit that drives the collimator lens 15 in a direction parallel to the optical axis (X-axis direction) is installed in the collimator unit 14. The DDL processing apparatus further includes a control unit that controls the lens driving unit.

  The laser processing machine 13 further includes a processing table 21 on which the workpiece W is placed, a portal X-axis carriage 22 that moves in the X-axis direction on the processing table 21, and an X-axis direction on the X-axis carriage 22. And a Y-axis carriage 23 that moves in the Y-axis direction perpendicular to the axis. The collimator lens 15 in the collimator unit 14, the dispersive element 16, and the condenser lens 18 in the processing head 17 are fixed to the Y-axis carriage 23 in a state where the optical axis is adjusted in advance. Move in the axial direction. It is also possible to provide a Z-axis carriage that can move in the vertical direction with respect to the Y-axis carriage 23 and to provide the condenser lens 18 on the Z-axis carriage.

  The DDL processing apparatus according to the embodiment of the present invention irradiates the workpiece W with the laser beam LB having the smallest condensing diameter (minimum condensing diameter) condensed by the condensing lens 18 and coaxially assist gas. The X-axis carriage 22 and the Y-axis carriage 23 are moved while the melt is removed by spraying. Thereby, the DDL processing apparatus can cut the workpiece W. Examples of the workpiece W include various materials such as stainless steel, mild steel, and aluminum. The plate thickness of the workpiece W is, for example, about 0.1 mm to 50 mm.

  Next, the laser oscillator 11 will be described with reference to FIGS. 2A and 2B, the laser oscillator 11 includes a housing 60, the DDL module 10 housed in the housing 60 and connected to the transmission fiber 12, and the housing 60. A power supply unit 61 that is housed in the DDL module 10 and supplies power to the DDL module 10, a control module 62 that is housed in the housing 60 and controls the output of the DDL module 10, and the like are provided. An air conditioner 63 that adjusts the temperature and humidity in the housing 60 is installed outside the housing 60.

As shown in FIG. 3, the DDL module 10 superimposes and outputs laser beams of multiple wavelengths (λ ₁ , λ ₂ , λ ₃ ,..., Λ _n ). The DDL module 10 includes a plurality of laser diodes (hereinafter referred to as “LD”) 3 ₁ , 3 ₂ , 3 ₃ ,... 3 _n (n is an integer of 4 or more), LD 3 ₁ , 3 ₂ , 3 ₃ , · · · _{3 n} to the fiber _{4 1,} 4 2, _{4 3,} is connected via a · · · _{4 n,} multiple wavelengths lambda _1, lambda _2, lambda _3, · · ·, to the laser beam of lambda _n A spectral beam combining unit 50 that performs spectral beam combining and a condensing lens 54 that condenses the laser light from the spectral beam combining unit 50 and enters the transmission fiber 12 are provided.

Multiple _{LD3 1, 3 2, 3 3} , as a · · · _{3 n,} various kinds of semiconductor lasers can be employed. The combination of the types and numbers of LD3 ₁ , 3 ₂ , 3 ₃ ,... 3 _n is not particularly limited, and can be appropriately selected according to the purpose of sheet metal processing. _{LD3 1, 3 2, 3 3} , ··· 3 wavelengths _{n λ 1, λ 2, λ} 3, ···, λ n , you can select, for example, less than 1000 nm, or selected in the range of 800nm~990nm , In the range of 910 nm to 950 nm.

The laser beams having multiple wavelengths λ ₁ , λ ₂ , λ ₃ ,..., Λ _n are controlled by group (block) management for each wavelength band, for example. The output can be variably adjusted individually for each wavelength band. In addition, the output of the entire wavelength band can be adjusted so that the absorptance is constant.

In the cutting process, LD3 ₁ , 3 ₂ , 3 ₃ ,... 3 _n are simultaneously operated, and an appropriate assist gas such as oxygen or nitrogen is blown near the focal position. As a result, the laser beams of the respective wavelengths from the LD 3 ₁ , 3 ₂ , 3 ₃ ,... 3 _n cooperate with each other and also with the assist gas such as oxygen to melt the workpiece at a high speed. Further, the molten work material is blown off by the assist gas, and the work is cut at a high speed.

The spectral beam combining unit 50 includes a fixing unit 51 that bundles and fixes the emission ends of the fibers 4 ₁ , 4 ₂ , 4 ₃ ,... 4 _n to form a fiber array 4 and fibers 4 ₁ , 4 ₂ , 4 ₃ , a collimator lens 52 to the laser light into parallel light from · · · 4 _n, multiple wavelengths _{λ 1, λ 2, λ 3} , ···, a diffraction grating for matching an optical axis diffracting a laser beam of lambda _n (Diffraction grating) 53 and LD3 ₁ , 3 ₂ , 3 ₃ ,... 3 _n are provided with a partial reflection coupler 55 that constitutes a resonator together with a reflection surface provided at the rear end. In FIG. 3, the partial reflection coupler 55 is disposed at the subsequent stage of the diffraction grating 53 as an example, but the arrangement position of the partial reflection coupler 55 is not limited to this.

Here, in the laser oscillator 11, temperature management required for the LDs 3 ₁ , 3 ₂ , 3 ₃ ,... 3 _n and temperatures required for optical elements such as the collimator lens 52, the diffraction grating 53, and the condenser lens 54. There is a difference in strictness with management. That is, _if the cooling temperature of LD3 ₁ , 3 ₂ , 3 ₃ ,... 3 _n is within the specified temperature, there is no significant change in the electro-optical conversion efficiency. Also, the lower the temperature, the longer the service life. Therefore, it is only necessary to select a low temperature as much as possible within the allowable range of the dew point, and to cool at a fixed value. On the other hand, the optical elements such as the collimator lens 52, the diffraction grating 53, and the condenser lens 54 also include a portion used for resonance, which significantly affects the diffraction phenomenon and the like, so that LD3 ₁ , 3 ₂ , 3 _3, it is necessary to strictly temperature control than · · · 3 _n.

Therefore, in the embodiment of the present invention, as shown in FIG. 4, an LD cooling device 70 is connected to the LD group 3 of the DDL module 10, and independently of this, the optical elements 52, Optical element cooling devices 71, 72, 73 are connected to 53, 54. The LD group 3 shown in FIG. 4 includes the LDs 3 ₁ , 3 ₂ , 3 ₃ ,... 3 _n shown in FIG. A similar optical element cooling device may be connected to the partial reflection coupler 55 shown in FIG.

  As the LD cooling device 70 and the optical element cooling devices 71, 72, 73, various cooling methods such as a chiller type or a Peltier type can be used. The LD cooling device 70 and the optical element cooling devices 71, 72, and 73 may be the same device or different devices. The cooling devices 71, 72, 73 for optical elements may use the same device or different devices.

  The LD cooling device 70 is connected to the LD group 3 via a cooling path 70a. A temperature sensor 70 b is attached to the LD group 3. Two or more temperature sensors may be attached to the LD group 3. The temperature data detected by the temperature sensor 70 b is fed back to the temperature control function unit of the LD cooling device 70. For example, the control unit 62 controls the set temperature of the LD cooling device 70 based on the temperature data detected by the temperature sensor 70b so that the temperature of the LD group 3 is equal to or lower than a predetermined threshold.

  4 shows a case where one LD cooling device 70 cools the LD group 3, but the number of LDs to be cooled by the LD cooling device 70 is not particularly limited. In order to maintain the accuracy of output for each wavelength band, an LD cooling device may be provided for each group-managed wavelength band.

  On the other hand, the optical element cooling devices 71, 72, and 73 cool the optical elements 52, 53, and 54 in a separate system from the LD cooling device 70. The optical element cooling devices 71, 72, 73 are connected to the optical elements 52, 53, 54 via cooling paths 71a, 72a, 73a. The optical element cooling devices 71, 72, 73 distribute cooling water and the like using a distributor (not shown) and circulate the cooling paths 71a, 72a, 73a.

  The cooling paths 71a, 72a, 73a are arranged in the vicinity of the optical elements 52, 53, 54, such as the side walls and the bottom surface of the spectral beam coupling unit 50, etc. so as to contribute to the cooling of the optical elements 52, 53, 54. ing. In the vicinity of each optical element 52, 53, 54, temperature sensors 71b, 72b, 73b are attached. The temperature sensors 71b, 72b, and 73b may not be provided for each of the optical elements 52, 53, and 54. For example, one temperature sensor may be attached to the optical elements 52, 53, and 54.

  The temperature data detected by the temperature sensors 71b, 72b, and 73b is fed back to the temperature control function unit of the optical element cooling devices 71, 72, and 73. For example, data on the relationship between the temperature of each optical element 52, 53, 54 and the output of the exit end of the transmission fiber 12, the processing point, etc. is obtained in advance by experiments and the allowable temperature based on the data. Set the range for each output. When the temperature measured by the temperature sensors 71b, 72b, and 73b exceeds the allowable temperature range, the control unit 62 adjusts the temperature of the optical element cooling devices 71, 72, and 73 so that the temperature is within the allowable temperature range. Change each setting value.

The temperature ranges of the optical elements 52, 53, 54 controlled by the optical element cooling devices 71, 72, 73 are LD3 ₁ , 3 ₂ , 3 ₃ ,... 3 _n controlled by the LD cooling device 70. It may be narrower than the temperature range. In this case, the temperature management of the optical elements 52, 53, 54 can be performed more strictly than the temperature management of the LD group 3. For example, the LD cooling device 70 controls the temperature of the LD group 3 to ± 5% of the set temperature (for example, 25 ° C.). On the other hand, the optical element cooling devices 71, 72, 73 control the temperature of the optical elements 52, 53, 54 to ± 3% of the set temperature (for example, 30 ° C.).

  According to the present invention, in the laser oscillator 11, in addition to the cooling path 70a and the LD cooling device 70 for cooling the LD group 3, the cooling paths 71a, 72a and 73a for cooling the optical elements 52, 53 and 54 are provided. Also, by providing the optical element cooling devices 71, 72, 73 independently, the temperature of the optical elements 52, 53, 54 can be controlled separately from the LD group 3. Therefore, even when the outside air temperature or the temperature of the cooling water of the LD group 3 fluctuates, the optical elements 52 and 53 disposed between the resonators (when the partial reflection coupler 55 is disposed behind the condenser lens 54, The temperature of the optical elements 52, 53, 54) can be individually controlled. Therefore, the reliability of the optical elements 52, 53, and 54 can be obtained, and the laser output can be stabilized.

  In addition, the values of the temperature sensors 71b, 72b, 73b attached to the optical elements 52, 53, 54 are fed back to change the set temperatures of the optical element cooling devices 71, 72, 73, which is optimal for spectral beam coupling. Temperature control can be performed. In addition, by suppressing the temperature of the optical elements 52, 53, and 54 within an allowable temperature range so that output fluctuation does not occur, the laser output can be stabilized.

(Other embodiments)
Although the present invention has been described with reference to embodiments, it should not be understood that the description and drawings that form part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  In FIG. 4, the case where one optical element cooling device 71, 72, 73 is provided for each of the optical elements 52, 53, 54 has been described, but the number of optical element cooling devices and the cooling by one optical element cooling device The number of optical elements to be used is not particularly limited. For example, when the temperature ranges in which the plurality of optical elements 52, 53, and 54 are managed are the same, as shown in FIG. 5, one optical element cooling is performed for the plurality of optical elements 52, 53, and 54. A device 71 may be provided.

  The optical elements to be cooled by the optical element cooling devices 71, 72, 73 are not particularly limited to the collimator lens 52, the diffraction grating 53, and the condenser lens 54, and other optical elements in the DDL module 10 are used. There may be.

  The sheet metal processing by the DDL processing apparatus according to the embodiment of the present invention can be applied to various sheet metal processing such as laser forming processing, annealing, annealing, and ablation in addition to cutting processing.

  As described above, the present invention naturally includes various embodiments not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

3 ... LD group 10 ... DDL module 11 ... Laser oscillator 12 ... Transmission fiber (process fiber)
DESCRIPTION OF SYMBOLS 13 ... Laser processing machine 14 ... Collimator unit 15 ... Collimator lens 16 ... Bend mirror 17 ... Processing head 18 ... Condensing lens 21 ... Processing table 22 ... X-axis carriage 23 ... Y-axis carriage 3 ₁ , 3 ₂ , 3 ₃ ,. .... 3 _n Laser diode (LD)
4 ₁ , 4 ₂ , 4 ₃ ,... 4 _n ... Fiber 50... Spectral beam coupling part 51... Fixed part 52.
53 ... Diffraction grating (optical element)
54 ... Condensing lens (optical element)
55. Partial reflection coupler (optical element)
DESCRIPTION OF SYMBOLS 60 ... Housing 61 ... Power supply part 62 ... Control module 63 ... Air conditioning equipment 70 ... LD cooling device 71, 72, 73 ... Optical element cooling device 71a, 72a, 73a ... Cooling path 71b, 72b, 73b ... Temperature sensor 70a ... Cooling path 70b ... Temperature sensor

Claims (5)

A plurality of laser diodes each outputting multi-wavelength laser light;
An optical element for receiving multi-wavelength laser light output by the plurality of laser diodes;
A cooling device for LD that cools at least one of the plurality of laser diodes;
A direct diode laser oscillator comprising: an optical element cooling device that cools the optical element in a separate system from the LD cooling device.   2. The direct diode laser according to claim 1, wherein a temperature range of the optical element controlled by the cooling device for the optical element is narrower than a temperature range of the laser diode controlled by the cooling device for the LD. Oscillator.   The direct diode laser oscillator according to claim 1 or 2, wherein the LD cooling device controls the laser diode at ± 5% of a set temperature.   4. The direct diode laser oscillator according to claim 1, wherein the optical element cooling device controls the optical element at ± 3% of a set temperature. 5. A plurality of the optical elements;
The direct diode laser oscillator according to claim 1, wherein the optical element cooling device cools the plurality of optical elements.

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