JP6130427B2 - Laser module - Google Patents

Description

The present invention relates to a laser module, and more particularly to a laser module configured to obtain high-power laser light by combining laser light emitted from a plurality of LDs (laser diodes).

  Laser light is used in various fields such as a material processing field represented by metal and a medical field by utilizing its high energy density. Particularly in the field of material processing, the output of laser light is increased for the purpose of shortening the processing time.

Lasers that are frequently used in the material processing field are broadly classified into fiber laser systems and DDL (Direct Diode Laser) systems.
Hereinafter, both will be briefly described.

A general fiber laser has a structure described in Patent Document 1 and the like.
That is, the signal light generated from the signal light source and the pump light generated from the pump light source are input to an amplification optical fiber having a core doped with a rare earth element via an optical coupler, and the pump light is added to the core. By acting on the rare earth element, the signal light propagating through the core of the amplification optical fiber is amplified to obtain a laser beam having high energy.

  One way to increase the output of a fiber laser is to increase the output of signal light and pumping light. The method of increasing the output of signal light and pumping light is used for LD modules used as light sources. The number of LDs to be increased may be increased.

The DDL uses a module in which a plurality of LDs are combined as described in Patent Document 2, and each laser beam emitted from each LD is combined into one light using a condensing member such as a lens. In this method, the object to be processed is directly irradiated. In order to increase the output of DDL, the number of LDs used should be increased.

As described above, in order to increase the output of a laser, it is important to use a module with a high output using a large number of LDs, and various modules have been proposed. Patent Documents 3 and 4 are examples of increasing the output of the module by increasing the number of LDs.

In Patent Document 3, a plurality of LD installation surfaces having different heights are prepared, LDs are arranged on each LD installation surface, a mirror is arranged on each LD installation surface, and each laser beam reflected by the mirror is collected by a lens. Increasing the output of the module by light.

In Patent Document 4, an LD and a double mirror are arranged on the same substrate, and each laser beam reflected by the double mirror is condensed by a lens, and the module is arranged on the substrate. In this module, an LD is arranged on a stepped mount and mirrors having different heights are arranged directly on the substrate, and each laser beam reflected by the mirror is condensed by a lens to increase the output. Yes.

However, in the module described in Patent Document 3, it is necessary to suppress the mirror height to about 1000 μm so as not to interfere with the laser beam reflected by the subsequent mirror, and thus the dimensional accuracy requirement for the mirror height becomes severe. At the same time, the handling thereof is difficult, and the workability of the module assembly is difficult.

On the other hand, in the module described in Patent Document 4, the mirror is relatively easy to handle, but when using a double mirror, the cost of the double mirror is expensive and the mirror is reflected by the latter mirror. It takes time to adjust the mirror position so as not to interfere with the laser.
Also, when arranging LDs on a staircase mount, it is necessary to prepare mirrors whose height is changed by the number of LDs, and when increasing the number of LDs for higher output, they are prepared. The number of types of mirrors has increased and there are difficulties in terms of component management.

JP 2007-103751 A JP 2007-142439 A JP2013-235934A JP 2014-126852 A

An object of the present invention is to provide an LD module that is excellent in assembling workability and can suppress an increase in the number of necessary parts even if the number of LDs is increased for high output.

As a result of earnestly examining the configuration of the laser module, the inventor employs a configuration using the first step portion for installing the LD and the second step portion for installing the reflector. It was found that can be solved.

The laser module of the present invention has a housing, a plurality of LDs, a plurality of reflectors, a condenser lens, a first step portion, and a second step portion.
The first staircase portion and the second staircase portion are provided on the bottom plate of the housing,
Each of the plurality of LDs is provided on an LD installation surface formed in a step shape on the first step portion,
Each of the plurality of reflectors is provided on a reflector installation surface formed stepwise on the second stepped portion,
Each laser emitted from the plurality of LD, after passing through the fast axis direction collimating lens and the slow-axis direction collimating lens, the traveling direction changed by the reflector of the plurality of, with is then synthesized by the condenser lens ,
The height difference of each LD installation surface of the first step portion is equal to the height difference of each reflector installation surface of the second step portion,
The height of the LD installation surface from the bottom plate is higher than the height from the bottom plate of the reflector installation surface provided with the reflector corresponding to the laser emitted by the LD provided on the LD installation surface. ,
The slow axis collimating lens through which the laser emitted by the LD provided on the lowermost LD installation surface of the first stepped portion transmits is inclined with respect to the bottom plate toward the first stepped portion,
The slow axis collimating lens through which the laser emitted by the LD provided on the uppermost LD installation surface of the first staircase portion transmits is inclined with respect to the bottom plate toward the second staircase portion;
It is characterized by.

The laser module of the present invention has the following excellent effects.

-By dividing the LD installation step and the reflector installation step, the dimensions of the reflectors used can be unified.

As a result, even when the number of LDs is increased to increase the output, it is not necessary to change the size of the reflector, the parts management is easy, and the productivity of the laser module is improved.

It is a basic configuration of the present invention. It is an example of LD used for this invention. It is explanatory drawing of the height change of a laser beam by the inclination of a slow axis collimating lens. It is an example of the Example of this invention.

Hereinafter, embodiments of the laser module of the present invention will be described with reference to FIG. FIG. 1 shows the present invention when the number of LDs is five. The number of LDs is not limited to five, and may be increased or decreased according to the desired output.

In FIG. 1, 1 is a laser module of the present invention, 2a is a bottom plate of a housing, 3 is an LD, 4 is a reflector, 5 is a first step portion, 6 is a second step portion, 7 is a condenser lens, 8 is Laser light.
What is characteristic of the present invention is that the first staircase portion 5 and the second staircase portion 6 are provided on the bottom plate 2a of the casing, and each of the plurality of LD3 is formed in a staircase pattern on the first staircase portion 5. It is provided on the installation surface, and each of the plurality of reflectors 4 is provided on the reflector installation surface formed in the second staircase portion 6 in a step shape.

The first staircase portion 5 and the second staircase portion 6 are provided on the bottom plate 2a, each of the plurality of LD3 is provided on the LD installation surface formed on the first staircase portion 5, and each of the plurality of reflectors 4 is provided on the second staircase. Since the height difference between the height of the installation surface of each LD 3 and the height of the corresponding installation surface of the reflector 4 can be kept constant by providing it on the reflector installation surface formed in the portion 6, the reflector 4 The dimensions can be unified.
For this purpose, as will be described later, the height difference of each reflector installation surface is formed to be equal to the height difference of each LD installation surface of the first staircase portion 5, and as shown in FIG. The first staircase is such that the height of the installation surface from the bottom plate is higher than the height of the reflector installation surface provided with the reflector 4 corresponding to the laser emitted by the LD 3 provided on the LD installation surface. The part 5 and the second staircase part 6 are formed.

  An example of the LD 3 used in the present invention is shown in FIG. The LD 3 has a configuration in which an LD element, and a positive electrode and a negative electrode that supply current for driving the LD element are provided on a submount. This configuration is an example, and the LD 3 used in the present invention may take other configurations within the scope of the technical idea of the present invention. The LD 3 is insulated from the first staircase portion 5.

After synthesizing each laser beam 8 with the condensing lens 7, the object may be directly irradiated with the laser beam 8, or, as in an embodiment described later, coupled to an optical fiber and laser beam to a required place. 8 may be guided.
Hereinafter, a case where the laser beam 8 is coupled to an optical fiber will be described.

It is not always necessary to provide all of the reflectors 4 in the second staircase portion 6, and the lowermost reflector 4 may be provided directly on the bottom plate 2 a as in an embodiment (FIG. 4) described later.
When the reflector 4 is provided on the bottom plate 2a, the size in the height direction of the housing can be reduced, which is advantageous in terms of downsizing the laser module.
In this case, as shown in FIG. 4, the lowermost LD installation surface of the first staircase portion 5 is made higher than the surface of the bottom plate, and the LD except the lowermost LD installation surface of the first staircase portion 5 is used. The height of the installation surface from the bottom plate is higher than the height of the reflector contact installation surface provided with the reflector 4 corresponding to the laser emitted by the LD 3 provided on the LD installation surface from the bottom plate. A staircase portion 5 and a second staircase portion 6 are formed.

The first staircase portion 5 and the second staircase portion 6 may be integrally formed with the bottom plate 2a, or may be manufactured as separate parts and fixed on the bottom plate 2a.
In the case of integral molding, since the thermal resistance between the bottom plate and the staircase is reduced, it becomes an excellent aspect of heat dissipation, while in the case of separate parts, the bottom plate and the staircase can be made of different materials. Design that takes advantage of the difference in characteristics is possible.

  Both the first staircase portion 5 and the second staircase portion 6 may be integrally formed with the bottom plate 2a or may be separate parts, or only one of them may be a separate part.

As a material for the bottom plate 2a, the first staircase portion 5, and the second staircase portion 6, a material such as copper or aluminum having excellent thermal conductivity may be used. In addition, nickel plating, nickel + gold plating, or the like may be applied as necessary in order to improve the corrosion resistance.

As an effect of plating the bottom plate 2a and the like, the reflectance of the material surface can be increased. By increasing the reflectivity of the material surface, the amount of laser light 8 that is unexpectedly removed from the optical path is absorbed by the material, and heat generation of the housing or the like can be suppressed.
However, it is not always necessary to increase the reflectance of the material surface, and the material surface may absorb the laser light 8 in a situation where the casing is sufficiently cooled by the cooling means.

The laser module 1 is preferably configured so that the laser light 8 emitted from the plurality of LDs 3 passes through the fast axis collimating lens 9 and the slow axis collimating lens 10 and then reaches the reflector 4. .
By passing through the fast axis collimating lens 9 and the slow axis collimating lens 10, when the plurality of laser beams 8 are combined by the condenser lens 7, the diameter of the combined laser beams is inadvertently increased and energy is increased. It is possible to prevent the density from being reduced.

In addition, it is preferable that a part of the slow axis direction collimating lens 10 is inclined with respect to the bottom plate 2a as shown in FIG.
By providing the slow axis collimating lens 10 with an inclination, the laser beam 8 transmitted through the slow axis collimating lens 10 changes the height of the optical path with respect to the bottom plate 2a due to refraction.
By utilizing this, the spread in the height direction of the laser light 8 reaching the condenser lens 7 can be suppressed, and an increase in the diameter of the condenser lens 7 can be prevented, and light having a small core diameter can be prevented. The laser beam 8 can be easily coupled to the fiber.

As the condenser lens 7 used in the present invention, it is preferable to use an aspherical lens. By using an aspheric lens, the aberration that occurs when the laser beam 8 is condensed is reduced. As a result, the laser beam 8 can be collected efficiently, and the coupling efficiency to the optical fiber is increased.
Moreover, when the focused laser beam 8 is directly irradiated onto the object, the energy density of the laser beam 8 in the irradiation section can be increased.

When irradiating the target with the laser beam 8 using the laser module 1 as in the present invention, the laser beam 8 reflected from the surface of the target returns to the laser module 1 and reverses the optical path of the laser beam. There is a case where the LD 3 is damaged.
The protective reflector 16 for preventing this is preferably provided between the condenser lens 7 and the reflector 4 as shown in FIG. When the direction in which the laser beam 8 emitted from the LD 3 travels is defined as the downstream side of the optical path and the opposite direction is defined as the upstream side of the optical path, the protective reflector 16 transmits the laser beam toward the downstream side and travels toward the upstream side. It has a function of reflecting laser light on its surface, and a half mirror or the like can be used.

The protective reflector 16 is preferably provided such that its surface is inclined with respect to the central axis of the condenser lens 7. By providing the protective reflector 16 in this way, the reflected laser light that has returned along the central axis of the condenser lens 7 can be reflected in a direction inclined with respect to the central axis of the condenser lens 7, Inadvertently irradiating the object with the reflected laser beam reflected by the protective reflector 16 can be prevented.

By processing the reflected laser light reflected by the protective reflector 16 on the inner wall surface of the housing, the reflected laser light can be processed without causing a fatal effect on the operation of the laser module 1. Can do. At this time, it is preferable that the inner wall surface of the casing irradiated with the reflected laser light is subjected to a process of absorbing the reflected laser light.

  As an embodiment of the present invention, FIG. 4 shows a laser module capable of outputting 100 W class laser light. Hereinafter, the direction in which the laser beam 8 emitted from the LD 3 travels is defined as the downstream side of the optical path, and the opposite direction is defined as the upstream side of the optical path.

  As the bottom plate 2a of the housing 2, a copper plate with nickel plating was prepared.

As the side wall 2b of the housing 2, a nickel-plated stainless steel frame was prepared and joined to the bottom plate 2a by brazing.
An electrode 11 for supplying a current for driving the LD 3 and an insertion hole for inserting the optical fiber 12 are provided in the frame in advance, and the electrode 11 is inserted with insulation from the frame.
In FIG. 4, the front side wall 2b is omitted.

  As the first staircase portion 5, a copper block provided with 10 LD installation surfaces was prepared. The height difference between adjacent LD installation surfaces and the area of each LD installation surface are formed to be equal.

  A commercially available LD 3 having a wavelength of 915 nm and an output of 12 W is mounted on each LD installation surface of the first staircase portion 5, and a lead frame (not shown) for supplying a drive current between the positive electrode and the negative electrode of the LD 3. ). In calculation, the output of the laser module is 120W.

A first cylindrical lens was provided as a fast axis direction collimating lens 9 on the front surface of each LD 3.

As described above, after assembling necessary parts for the first step portion 5 and the LD 3, the first step portion 5 is joined to a predetermined place of the bottom plate 2a by brazing.
Thereafter, a conductive plate 13 insulated from the bottom plate 2a is provided so as to be parallel to the first staircase portion 5, and the positive electrode of the electrode 11 and the LD 3 installed at the top of the first staircase portion 5, the first staircase portion. 5 and the conductive plate 13, and the conductive plate 13 and the negative electrode of the electrode 11 were each connected by a lead frame (not shown).

  A copper block provided with nine reflector installation surfaces was prepared as the second staircase 6. The height difference of adjacent reflector installation surfaces and the area of each reflector installation surface are formed to be equal, and the height difference of each reflector installation surface is the height of each LD installation surface of the first staircase 5. It is formed to be equal to the difference.

On each reflector installation surface of the second staircase section 6, a mirror was installed as the reflector 4. When the first step portion 5 and the second step portion 6 are arranged in parallel, the mirror reflects the laser light 8 (not shown in FIG. 4) emitted from the LD 3 and changes its traveling direction by 90 °. Install in the direction you want.
The height of the mirror was set such that the laser beam 8 reflected by the mirror installed at the upper stage of the second staircase portion 6 did not interfere with the mirror installed at the lower stage of the second staircase portion 6.

  The second staircase section 6 is placed on the bottom plate 2a so that the mirror installed at the top stage of the second staircase section 6 reflects the laser beam 8 emitted from the LD 3 installed at the top stage of the first staircase section 5. Joined by brazing. The second staircase portion 6 was arranged in parallel to the first staircase portion 5.

As the reflector 4 that reflects the laser beam 8 emitted from the LD 3 installed at the lowest stage of the first staircase section 5, the same mirror as the mirror installed on the second staircase section 6 was fixed on the bottom plate 2 a.
The position of the mirror is assumed that a virtual installation surface having the same area as the reflector installation surface of the second staircase unit 6 is continuously present from the second staircase unit 6 below the lowermost step of the second staircase unit 6. Install on this virtual installation surface.
Like the mirror installed on the second staircase 6, the mirror installed on the virtual installation surface changes the traveling direction of the laser beam 8 emitted from the LD 3 installed on the lowest stage of the first staircase 5 by 90 °. Install in the direction you want.
About the height of the mirror, it set similarly to the mirror installed in the 2nd step part 6. FIG.

Subsequently, the slow axis collimating lens 10 is installed. The slow axis direction collimating lens 10 is provided on the downstream side of the fast axis direction collimating lens 9 and on the upstream side of the reflector 4.

  The slow axis collimating lens 10 is temporarily placed at a predetermined location, and the laser beam 8 is irradiated by driving the LD 3. While observing the laser beam 8 whose traveling direction is changed by the reflector 4 with a camera, the inclination angle of each slow axis collimating lens 10 with respect to the bottom plate 2a is adjusted so that the spread in the height direction of the laser beam 8 falls within a predetermined range. adjust.

  As a result of the adjustment, the slow axis collimating lens 10 corresponding to the LD 3 installed on the upper stage side of the first staircase portion 5 is inclined toward the downstream side, and corresponds to the LD3 installed on the middle stage of the first staircase portion 5. The slow-axis direction collimating lens 10 has almost no inclination, and the slow-axis direction collimating lens 10 corresponding to the LD 3 installed on the lower side of the first staircase portion 5 is inclined toward the upstream side.

When the tilt adjustment of the slow axis collimating lens 10 was completed, the slow axis collimating lens 10 was fixed to the bottom plate 2a using an adhesive.

As the condenser lens 7, a lens holder 14 with an aspheric lens fixed thereto was used.
The lens holder 14 is fixed to the bottom plate 2a by brazing so that the central axis of the condenser lens 7 is along the optical axis of the laser beam 8 reflected by the mirror.

After fixing the lens holder 14 to the bottom plate 2a, the rectangular parallelepiped glass block 15 was bonded and fixed so that the bottom surface was in contact with the bottom plate 2a and one side surface thereof was in contact with the lens holder 14.
The glass block 15 has an effect of suppressing the center axis of the condenser lens 7 from being shifted from the optical axis of the laser light 8 due to thermal expansion of the lens holder 14 when the laser module 1 generates heat by driving the LD 3. .

The bottom portion on the upstream side of the lens holder 14 has a surface inclined with respect to the traveling direction of the laser light 8. A half mirror is provided as a protective reflector 16 on the inclined surface.

  The region of the side wall 2b irradiated with the return laser beam reflected by the half mirror was peeled off the nickel plating to improve the return laser beam absorption capability.

The optical fiber 12 is disposed so that the incident end face of the optical fiber is located at the focal point of the condensing lens 7, and the condensed laser light 8 is configured to be coupled to the optical fiber 12.

  The optical fiber 12 was placed on a copper optical fiber fixing block 17 fixed on the bottom plate 2a, and fixed using solder.

In the part where the optical fiber 12 penetrates the side wall 2b, the optical fiber 12 was inserted into the ferrule 18 and fixed, and the ferrule 18 was fixed to the side wall 2b.

The housing top plate was fixed on the side wall 2b by brazing, and the laser module 1 was completed.

When the completed laser module 1 was driven and the output of the laser beam 8 emitted from the optical fiber 12 was measured, an output of 100 W was confirmed.
The output is 120W in calculation, but considering the loss of output in the actual use environment, such as part of the output being absorbed when passing through the lens and optical fiber, it is a laser module that outputs 100W class laser light. It can be said that the necessary and sufficient output was obtained.

As described above, a laser module having necessary and sufficient performance and excellent productivity was obtained.

The laser module of the present invention can be used in various scenes and applications where a laser module having a plurality of LDs is required, including a laser device for material processing.

DESCRIPTION OF SYMBOLS 1 Laser module 2 Case 2a Case bottom plate 2b Case side wall 3 Laser diode (LD)
4 reflector 5 first step portion 6 second step portion 7 condenser lens 8 laser beam 9 fast axis direction collimator lens 10 slow axis direction collimator lens 11 electrode 12 optical fiber 13 conductive plate 14 lens holder 15 glass block 16 protective reflector 17 Optical fiber fixing block 18 Ferrule

Claims (4)

A laser module having a housing, a plurality of LDs (laser diodes), a plurality of reflectors, a condenser lens, a first step portion, and a second step portion,
The first staircase portion and the second staircase portion are provided on the bottom plate of the housing,
Each of the plurality of LDs is provided on an LD installation surface formed in a step shape on the first step portion,
Each of the plurality of reflectors is provided on a reflector installation surface formed stepwise on the second stepped portion,
Each laser emitted from the plurality of LD, after passing through the fast axis direction collimating lens and the slow-axis direction collimating lens, the traveling direction changed by the reflector of the plurality of, with is then synthesized by the condenser lens ,
The height difference of each LD installation surface of the first step portion is equal to the height difference of each reflector installation surface of the second step portion,
The height of the LD installation surface from the bottom plate is higher than the height of the reflector installation surface provided with the reflector corresponding to the laser emitted by the LD provided on the LD installation surface from the bottom plate,
The slow axis collimating lens through which the laser emitted by the LD provided on the lowermost LD installation surface of the first stepped portion transmits is inclined with respect to the bottom plate toward the first stepped portion,
The slow axis collimating lens through which the laser emitted by the LD provided on the uppermost LD installation surface of the first staircase portion transmits is inclined with respect to the bottom plate toward the second staircase portion. A feature of the laser module. A laser module comprising a housing, a plurality of LDs, a plurality of reflectors, a condenser lens, a first staircase portion, and a second staircase portion, the first staircase portion and the second staircase portion The part is provided on the bottom plate of the housing,
Each of the plurality of LDs is provided on an LD installation surface formed in a step shape on the first step portion,
One of the plurality of reflectors is provided on the bottom plate of the housing, and each of the remaining reflectors is provided on a reflector installation surface formed in a step shape on the second stepped portion,
Each laser emitted from the plurality of LD, after passing through the fast axis direction collimating lens and the slow-axis direction collimating lens, the traveling direction changed by the reflector of the plurality of, with is then synthesized by the condenser lens ,
The height difference of each LD installation surface of the first step portion is equal to the height difference of each reflector installation surface of the second step portion,
The lowermost LD installation surface of the first staircase is higher than the surface of the bottom plate,
The height of the LD installation surface from the bottom plate excluding the lowermost LD installation surface of the first staircase portion is a reflector provided with a reflector corresponding to the laser emitted by the LD provided on the LD installation surface. Higher than the height of the installation surface from the bottom plate,
The slow axis collimating lens through which the laser emitted by the LD provided on the lowermost LD installation surface of the first stepped portion transmits is inclined with respect to the bottom plate toward the first stepped portion,
The slow axis collimating lens through which the laser emitted by the LD provided on the uppermost LD installation surface of the first staircase portion transmits is inclined with respect to the bottom plate toward the second staircase portion. A feature of the laser module. The laser module according to claim 1, wherein the condenser lens is an aspheric lens. The protective reflector is installed between the reflector that exists closest to the condenser lens among the reflectors, and the condenser lens. The laser module according to any one of the above.

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