JP3224775B2 - Semiconductor laser pumped slab solid-state laser device. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser-pumped slab solid-state laser apparatus using a semiconductor laser apparatus as a pump source and using a slab-type crystal, and more particularly to a case where a 100-W class semiconductor laser-pumped solid-state laser apparatus is realized. It is useful.

[0002]

2. Description of the Related Art Conventionally, a lamp-pumped solid-state laser device has been developed and commercialized as an infrared solid-state laser device for processing.

Since a wavelength having a band of 1 μm exists in the lowest loss region of the transmission characteristics of a quartz fiber (optical fiber), an optical fiber transmission of a high-power solid-state laser beam having a wavelength of about 1 μm becomes possible, and processing of a narrow portion can be performed. Three-dimensional processing, processing at a long distance, and processing in a radiation environment are possible. For example, since the oscillation wavelength of the Nd: YAG laser device, which is a solid-state laser device, is 1.064 μm, the laser beam of this YAG laser device can be transmitted through an optical fiber to perform the various kinds of processing described above.

The flexibility of laser processing by a solid-state laser device is expanded by connecting the tip of an optical fiber to a robot arm as well as a portal-type processing machine used in gas laser processing. Furthermore, the use of solid-state laser devices in not only laser processing but also other industrial fields, medical fields, and measurement fields is expected.

In a lamp-pumped solid-state laser device, light emitted from the entire circumference of the pump lamp is focused on a solid crystal by a reflecting cylindrical mirror, and this light is absorbed by a laser medium doped in the solid crystal. A laser medium comprising the excitation lamp and the solid crystal, and a pair of reflecting mirrors (partially transmitting output mirror and total reflecting mirror) arranged to face each other with the laser head interposed therebetween. By combining with a resonator constituted by a reflection mirror), laser oscillation from an optically pumped laser medium is enabled.

However, in such a conventional lamp-pumped solid-state laser device, the light emitted from the pump lamp has a wide wavelength distribution, and the wavelength component necessary for laser oscillation (excitation of the solid-state laser medium) is extremely small. One of the problems is that the oscillation efficiency is poor because it is small. Another problem is that frequent maintenance such as replacement of the excitation lamp is required because the life of the excitation lamp is short.

Therefore, in recent years, a semiconductor laser (Laser Diod) has been developed.
e; also referred to as LD) LD with the development of the device
Development of a solid-state laser device using the device as an excitation source has been progressing, and this LD-excited solid-state laser device has attracted attention as a solid-state laser device that can solve the problems of the conventional lamp-excited solid-state laser device. That is, by using an LD device instead of a lamp as the excitation source, the oscillation wavelength of the excitation source LD device can be tuned to the absorption wavelength of the solid-state laser medium. Contributes about 100% to the excitation of the solid-state laser medium, and the excitation efficiency of the solid-state laser medium increases.

For this reason, the LD-pumped solid-state laser device can oscillate with higher efficiency than the conventional lamp-pumped solid-state laser device, and the pump source can be a solid-state element, so that the life can be extended. Therefore, the LD-pumped solid-state laser device is expected to be a next-generation laser. However, at present, the laser output is several watts to several tens of watts which have been put to practical use. Therefore, it is desired that a LD-pumped solid-state laser device with higher output be put to practical use.

Therefore, there are two major problems in developing an LD-pumped solid-state laser device with higher output. The first problem is to increase the output of the pump source LD device, and the second problem is to improve the quality of the solid-state laser beam. Specifically, it is as follows.

First Problem (Higher Output of Excitation Source LD Device) There is a limit to the laser output that can be extracted from one LD element, and the laser output cannot be extracted beyond the optical damage of the LD light emitting end face. For example, in order to oscillate a 100 W solid-state laser beam, if the light-to-light conversion efficiency is 20%, an excitation source LD device capable of extracting a laser output of 500 W is required.
At present, such a laser output cannot be obtained with one LD element, and several W can be obtained with one LD element. Therefore, it is necessary to increase the output of the excitation source LD device by some method, but the mainstream at present is to integrate one-dimensional LD array elements in a two-dimensional array (two-dimensional LD array element), In this method, the laser outputs for the number of the integrated LD elements are summed to increase the output.

However, a problem with this method is a method of cooling each one-dimensional LD array element constituting the two-dimensional LD array element. That is, the electro-optical conversion efficiency of the LD element is not 100% but about 50%, and about 50% of the power supplied to the LD element is heat. The oscillation wavelength of the LD element has temperature dependence. For example, in the case of an AlGaAs one-dimensional LD array element, the oscillation wavelength is 0.3 nm per 1 ° C.
Change.

If the cooling of each one-dimensional LD array element constituting the two-dimensional LD array element is uniform and the temperature rise is uniform, as described in Japanese Patent Application Laid-Open No. 9-181376 described later, By selecting a one-dimensional LD array element in consideration of the wavelength shift amount of the oscillation spectrum corresponding to the wavelength, it is possible to tune to the absorption wavelength of the solid laser medium (808 to 809 nm in the case of the YAG laser medium). However, if the cooling of each one-dimensional LD array element is not uniform and the temperature of the LD element has a variation of, for example, 10 ° C., there is a variation of 3 nm as the oscillation wavelength due to the above temperature dependence. Part one-dimensional LD
The oscillation wavelength of the array element deviates from the absorption wavelength of the solid-state laser medium, leading to a decrease in the oscillation efficiency of the LD-pumped solid-state laser device. Therefore, it is necessary to uniformly cool each one-dimensional LD array element constituting the two-dimensional LD array element.

[0013] An LD device for exciting a solid-state laser for solving the above-mentioned problem is disclosed in Japanese Patent Application Laid-Open No. 9-181376. About this excitation source LD device,
This will be described below with reference to the drawings. FIG. 22 shows a conventional excitation source L
FIGS. 23 and 24 are perspective views of the D device, and are process diagrams showing a manufacturing process of the excitation source LD device.

As shown in FIG. 22, a large number of microchannels 16 having water passages 16a are stacked,
An insulator 17 and the one-dimensional LD array element 1 are interposed between these microchannels 16 in a planar manner so as not to overlap, and the microchannel 16 and the one-dimensional LD array element 1 are electrically connected. Thus, a two-dimensional LD array element composed of a large number of one-dimensional LD array elements 1 is formed, and a parallel direct cooling structure composed of a large number of microchannels 16 is formed. I have.

Further, the stacked micro channels 16
Manifolds 18 and 19 made of an insulating material are directly attached to both side surfaces (the inlet side and the outlet side of the water passage 16a). On the upper and lower surfaces of the one-dimensional LD array element 1, electrodes (anode, cathode) not shown are respectively arranged. The one-dimensional LD array element 1 is an element in which several tens of active media having a cross-sectional area of several μm × several hundred μm are arranged one-dimensionally.

The microchannel 16 and the one-dimensional L
As the adhesive for bonding to the D array element 1, a material having high conductivity is used. The microchannel 16 is formed as a unitary body of a conductive material and has no joint, and its water passage 16a is a single flow passage that allows cooling water to pass in only one direction. In FIG. 22, reference numerals 7 and 8 denote the inflow direction and outflow direction of the drive current, and reference numerals 9 and 10 denote the injection direction and the outflow direction of the cooling water.

Here, the manufacturing process of the excitation source LD device 2 will be described with reference to FIGS.

First, as shown in FIG. 23 (a), the microchannel 16 is placed horizontally, and as shown in FIG. 23 (b), the one-dimensional LD array element 1 on the microchannel 16 is installed. An insulating sheet (product name: Kapton, thickness 0.3 mm) 17 is attached to the surface other than the space,
An indium sheet (11 mm × 6 mm × 0.01 mm) 21 is arranged in a space where the one-dimensional LD array element 1 is installed.

Next, as shown in FIG. 23C, the one-dimensional LD array element 1 is laminated on the indium sheet 21. Further, as shown in FIG. The indium sheet 21 is laminated on the substrate. Subsequently, as shown in FIG. 23E, the microchannels 16 are stacked with the one-dimensional LD array element 1 and the indium sheet 21 interposed therebetween. By repeating the same process, the one-dimensional LD array element 1 and the like necessary to excite the solid-state laser medium are stacked to form a two-dimensional LD array element and a parallel direct Construct a cooling structure.

After that, as shown in FIG. 24A, the laminated product (for example, 42 stacks, 180 mm) is aligned with a surface perpendicular to the water channel direction, and then sandwiched between two support blocks 23. A bolt 25 is inserted through both ends of the support block 23, and a nut 24 is screwed to the bolt 25 and tightened. The tightening torque is controlled so that the multilayer film and the like in the LD element are not damaged by the pressure.

Further, as shown in FIG. 24B, these are placed on a heating plate 26 such as a hot plate, and N ₂ + H ₂
The indium sheet 21 is heated to 200 ° C. in an atmosphere to melt the indium sheet 21 having a melting point of 156 ° C. Then, by stopping the heating and cooling, the indium sheet 21 is solidified again to function as a conductive adhesive. Thus the excitation source LD
The body of the device 2 is manufactured. Similarly, two sets of the excitation source LD device main body are created. Finally, FIG.
As shown in FIG. 4 (c), manifolds 18 and 19 made of acrylic or Teflon are adhered to the inlet-side surface and the outlet-side surface of the microchannel group, respectively.

Therefore, in the excitation source LD device 2 having the above configuration, as shown in FIG. 22, when cooling water is supplied into the manifold 18 from the direction of arrow 9, this cooling water is supplied from the manifold 18 to each microchannel 16. After being diverted into the water channel 16a and flowing in parallel, they are collected in the manifold 19 and discharged in the direction of the arrow 10. That is, since the cooling water flows in the same direction at substantially the same distance to each microchannel 16 for the same time, each one-dimensional LD interposed between the microchannels 16 is formed by the uniform cooling water.
The array element 1 can be cooled uniformly. For this reason, the oscillation characteristics of the pump source LD device 2 are uniform, and the oscillation efficiency of the LD pumped solid-state laser device is improved, and high output can be achieved.

Second Problem (Quality Improvement of Solid-State Laser Beam) In quality enhancement of a solid-state laser beam, a rod-type crystal has conventionally been used as a solid crystal. For example, in a YAG laser device, a rod-type YAG crystal 31 as shown in FIG.
Has been used. In this case, as shown in FIG. 25A, the entire circumference of the rod-type YAG crystal 31 is irradiated with the excitation light 34 so that the solid-state laser beam 33 oscillates in the longitudinal direction of the rod-type YAG crystal 31. In addition, rod type YA
The entire circumference of the G crystal 31 is cooled by cooling water.

However, when high-power oscillation is performed using the rod-type YAG crystal 31, a radial temperature distribution is generated in the rod-type YAG crystal 31, as shown in FIG. As shown in FIG. 25 (c), the rod type Y
Due to the thermal lens effect in the AG crystal 31, the divergence angle θ of the YAG laser beam 33 extracted from the resonator 32 (partially transmitting reflection mirror 33a and total reflection mirror 32b) increases. As a result, the directivity, which is one of the characteristics of the laser beam, deteriorates, and the luminance (beam diameter × solid angle of beam spread) of the laser beam decreases. For this reason, even in various applications of the laser beam, the characteristics of the laser beam, such as long-distance propagation in a space and high energy density, cannot be utilized to the utmost.

Therefore, it is necessary to take measures to enable oscillation of a high-power solid-state laser beam and to improve the quality of the solid-state laser beam. Therefore, a slab crystal is used as a countermeasure. That is, a high-quality solid-state laser that suppresses the spread of the divergence angle by using a slab type crystal that has been developed not only for LD excitation but also for lamp excitation and performing thermal lens optical compensation by zigzag optical path propagation in this slab type crystal. The beam can be extracted.

That is, as shown in FIG. 26, a YAG laser device uses a slab type YAG crystal 41 having a rectangular cross section. As shown in FIG. 26A, both sides 41a and 41b of the slab type YAG crystal 41 are irradiated with an excitation light 34 such as a semiconductor laser beam to oscillate a YAG laser beam 42 in the longitudinal direction of the slab type YAG crystal 41. To do it. Further, both side surfaces 41a, 4a of the slab type YAG crystal 41 are formed.
1b is cooled by cooling water.

In this case, a temperature distribution occurs in the thickness direction t as shown in FIG. 26B, but in the slab type YAG crystal 41, light is emitted in the thickness direction t as shown in FIG. Since it is a zigzag optical path that reflects and reciprocates, the slab type YA
The effect of the thermal lens effect in the G crystal 41 is averaged, and the YAG laser beam 42 extracted from the resonator 43 (partially transmitting reflection mirror 43a and total reflection mirror 43b)
Has a smaller divergence angle θ.

[0028]

However, in the above prior art, in order to increase the output of the LD pumped slab solid-state laser device, it is necessary to cool the pump source LD device or to excite the solid-state laser device (irradiation of the semiconductor laser beam). ) And cooling of the slab crystal still have some problems as follows.

Problems Regarding Cooling of Excitation Source LD Device In the conventional excitation source LD device 2 shown in FIG. 22, when the cooling water flows into the water passage 16 a of each microchannel 16,
The flow of the cooling water is disturbed, and the degree of the disturbance is different for each water passage 16a. Further, the velocity distribution of the cooling water in the inlet-side manifold 18 is not uniform. That is, the velocity difference between the main flow in the center and the flow on both sides is relatively large (flow velocity of main flow> flow velocity on both sides). In addition, near the both side surfaces of the manifold 18, a boundary layer is generated due to a decrease in the flow rate of the cooling water due to friction with the side surfaces.

These facts indicate that each microchannel 1
6 causes unevenness in the flow velocity distribution of the cooling water flowing through the water passage 16a. As a result, the temperature of each one-dimensional LD array element 1 varies, and the oscillation characteristics of each one-dimensional LD array element 1 vary. And, consequently, the output of the LD-pumped slab solid-state laser device is reduced.

Problems Regarding Excitation (Semiconductor Laser Beam Irradiation) of Solid-State Laser Device For example, as shown in FIG. 27, a semiconductor laser beam oscillated from an excitation source LD device 2 (see FIG. 22) is converted into a slab type YA.
When irradiating the G crystal 41 to excite it, the details will be described later, but in order to effectively perform thermal lens optical compensation by zigzag optical path propagation and obtain a high quality YAG laser beam 42, the slab type YAG crystal 41 must be The temperature distribution in the thickness direction is a symmetrical temperature distribution with a peak at the center (see FIG. 26 (b)), and the temperature distribution in the lateral width direction and the longitudinal direction needs to be uniform. It is necessary to consider not only the irradiation of the beam on both side surfaces 41a and 41b of the slab type YAG crystal 41 but also the irradiation width of the semiconductor laser beam.

If a part or all of the semiconductor laser beam is not irradiated to the slab-type crystal due to the spread or reflection of the semiconductor laser beam (reflection from a transmission plate; details will be described later), an LD-pumped slab solid-state laser device is used. In this case, the oscillation efficiency decreases or the oscillation stops. Further, if the semiconductor laser beam is directly reflected on the pump source LD device, it will have a bad influence on the pump source LD device. Therefore, it is necessary to pay attention to such spread and reflection of the semiconductor laser beam and to devise the structure of the irradiation part of the semiconductor laser beam.

As shown by a dashed line in FIG. 27B, the slab-type YAG crystal 41 is stretched in the longitudinal direction by the heat generated by the irradiation of the semiconductor laser beam oscillated from the excitation source LD device 2. Due to the difference in extension between the 41a side and the side surface 41b side, it bends in the thickness direction (vertical direction in FIG. 27). If the slab-type YAG crystal 41 bends in this manner, the light cannot be maintained at a constant (30.9 °) reflection angle when the light propagates zigzag in the slab-type YAG crystal 41, so that the YAG laser beam 42 The divergence angle becomes large and the quality deteriorates.

As described above, in order to effectively perform thermal lens optical compensation by zigzag optical path propagation and obtain a high-quality solid-state laser beam, as described above, the temperature distribution in the thickness direction of the slab-type crystal is required. It is necessary to make the temperature distribution symmetrical with the peak at the center and to make the temperature distribution in the lateral width direction and longitudinal direction uniform, but for this purpose, only the both sides of the slab crystal are cooled, Need to be insulated.

When a water channel is formed by providing a transmission plate on both sides of the slab type crystal (details will be described later), it is necessary to securely seal the cooling water on the slab type crystal side and the transmission plate side, and a sealing member. It is desirable that the can be easily attached and detached.

Further, it is necessary to make the heat transfer coefficient from the slab type crystal to the cooling water flowing through the water channel as high as possible, and to cool the side surface of the slab type crystal as uniformly as possible from the viewpoint of the temperature distribution.

Of the above-mentioned problems, in particular,
An object of the present invention is to solve the above problems.

That is, in view of the above prior art, the present invention sets the irradiation width of a semiconductor laser beam appropriately, effectively performs thermal lens optical compensation by zigzag optical path propagation, and excites the entire semiconductor laser beam to a slab type crystal. Or a semiconductor laser beam irradiating portion having a structure capable of preventing bending of the slab-type crystal when the slab-type crystal is elongated by heat generation of the semiconductor laser beam.
It is an object to provide a D-pumped slab solid-state laser device.

[0039]

According to the present invention, there is provided a semiconductor laser-pumped slab solid-state laser device according to the present invention, wherein the semiconductor laser device is an excitation source and uses a slab-type crystal. A region corresponding to 15% of the entire length of the slab crystal at both ends in the longitudinal direction of the slab crystal is a non-irradiated region not irradiated with the semiconductor laser beam oscillated from the semiconductor laser device.

[0040]

[0041]

[0042]

[0043]

[0044]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a system diagram showing the overall configuration of an LD-pumped slab YAG laser device according to an embodiment of the present invention.
FIG. 3 is a side view showing the main body of the LD-excitation slab YAG laser device partially cut away (as viewed in the direction of arrow F in FIG. 3), FIG. 3 is a cross-sectional view taken along line AA in FIG. 2, and FIG. 2 is an enlarged cross-sectional view taken along the line BB of FIG. 2, FIG. 5 is an enlarged perspective view showing a main body of the excitation source LD device provided in the LD excitation slab YAG laser device, and FIG. 6 is provided in a manifold of the excitation source LD device. FIG. 7 is an enlarged view showing the slab holder portion of FIG. 3 extracted, and FIG. 8 is a cross-sectional view of a main part showing a configuration in the case where a collimating lens is provided.

FIG. 9 is an explanatory view showing a state where the irradiation width of the semiconductor laser beam is narrower than the side width of the slab type YAG crystal. FIG. 10 is a view showing the case where the entire side width of the slab type YAG crystal is irradiated with the semiconductor laser beam. FIG. 11 is an explanatory diagram showing a temperature distribution and a refractive index distribution in a slab type YAG crystal. FIG. 11 shows a case where the irradiation width of a semiconductor laser beam is smaller than the side width of the slab type YAG crystal (in the case of condensing irradiation) Slab type YA
FIG. 3 is an explanatory diagram showing a temperature distribution and a refractive index distribution in a G crystal.

FIG. 12 is an enlarged sectional view taken along the line DD of FIG.
13 is an enlarged view of a portion E in FIG. 4, FIG. 14 is a front view of the transmission plate holder (a view in the direction of arrow F in FIG. 7), FIG. 15 is a rear view of the transmission plate holder, and FIGS. ), (C),
(D) is a sectional view taken along line GG of FIG. 14, a sectional view taken along line HH, a sectional view taken along line JJ of FIG.
(A), (b) is a sectional view taken along line LL of FIG.
FIG. 18 is a sectional view taken along line M of FIG.
19 (a), 19 (b), and (c) are front, side, and back views of the transmission plate, and FIG. 20 is a diagram illustrating the main body of the LD-excited slab YAG laser device as an optical axis adjustment table. FIG. 21 is a side view showing an attached state, and FIG. 21 is an explanatory view showing a flow velocity distribution test result of cooling water flowing in the manifold.

<Structure> As shown in FIG. 1, the LD-excited slab YAG laser device 51 according to the present embodiment includes a device main body 52 and a cooling water circulation system 53. The apparatus main body 52 has a slab holder 54 for holding a slab-type YAG crystal 82 and a pair of excitation source LD devices 56 disposed on both sides of the slab holder 54 as excitation sources. These paired excitation source LD devices 56
Are symmetrical and have the same configuration.

The cooling water circulation system 53 includes one of the excitation sources LD.
A first cooling water loop 57 for circulating cooling water to the device 56;
It has three systems: a second cooling water loop 58 that circulates cooling water to the other excitation source LD device 56 and a third cooling water loop 59 that circulates cooling water to the slab holder 54. Is connected to the temperature-controlled cooling water circulator 60.

The one-dimensional LD array elements (not shown in FIG. 1) constituting the two-dimensional LD array elements of one of the excitation source LD devices 56 are cooled by the cooling water circulated in the first cooling water loop 57. The other excitation source LD device 56 is cooled by the cooling water circulated in the second cooling water loop 58.
Each of the one-dimensional LD array elements (not shown in FIG. 1) constituting the two-dimensional LD array element is cooled, and the slab type of the slab holder 54 is cooled by the cooling water circulated in the third cooling water loop 59. The YAG crystal 82 is cooled. In the third cooling water loop 59, the cooling water is divided on the way to cool both side surfaces of the slab type YAG crystal 82, and then merge again.

Pure water is used as the cooling water in order to enhance the electrical insulation. In addition, alcohol etc. can be used as a refrigerant other than cooling water, but water (pure water) is generally used.

Hereinafter, the configuration of the apparatus main body 52 will be described in detail with reference to FIGS.

As shown in FIGS. 2 and 3, an excitation source LD device main body 65 is provided at the center of the excitation source LD device 56. The excitation source LD device main body 65 includes a two-dimensional LD array element 61 formed by stacking a large number of one-dimensional LD array elements 64 and a microchannel group 62 formed by stacking a large number of microchannels 63.

That is, as shown in FIG. 5, the microchannel 63 having the water channel 63a and the one-dimensional semiconductor laser array element 64 are alternately stacked in the optical axis direction of the YAG laser beam (the direction of arrow X). Dimensional LD array element 6
1 and a micro channel group 62, and each micro channel 6 of the micro channel group 62
The three water passages 62a are parallel, and each one-dimensional LD array element 64 is directly cooled by cooling water flowing through each water passage 62a. The number of stacked one-dimensional LD array elements 64 depends on the solid-state laser device 5.
This is a number corresponding to the output of 1, for example, 42 elements.

Between the microchannels 63, besides the one-dimensional LD array element 64, this one-dimensional LD array element 6
The insulating members 66 are arranged in a plane so as not to overlap with the insulating members 4. In addition, each one-dimensional LD array element 64 is connected to the microchannel 6 by a conductive adhesive.
3 is electrically and physically bonded to the one-dimensional LD array element 64 so that electricity is supplied to the one-dimensional LD array element 64 in the stacking direction (the direction of the arrow X) of the one-dimensional LD array element 64 via an electrode (not shown). It has become. For this reason, it is necessary to select a material having excellent electrical conductivity and thermal conductivity as the material of the microchannel 16, and copper is selected in the present embodiment. The manufacturing process of the pump source LD device main body 65 is the same as that of the conventional pump source LD device 2 shown in FIG.
It is the same as the main body.

However, in the conventional excitation source LD device 2, no special attention was paid to the arrangement of the one-dimensional LD array element 1, whereas in the present excitation source LD device 56, FIGS. As shown, the section from the entrance of the water channel 63a of each microchannel 63 to a predetermined distance L is the approach section 6
7 at the position where the approaching section 67 is provided.
D array elements 64 are arranged respectively.

The distance L of the approach section 67 is a distance until the flow of the cooling water flowing into the water channel 63a of each micro channel 63 is stabilized. That is, when the cooling water flows into the water channel 63a of each micro channel 63,
The flow of the cooling water is disturbed, and the degree of the disturbance is different for each water passage 63a. However, the flow of each of these cooling waters becomes stable while flowing through each water passage 63,
The flow is uniform. Therefore, a section until the flow of the cooling water flowing into the water channel 63a of each micro channel 63 is stabilized as described above is referred to as a running section 67, and this running section 6
The one-dimensional LD array element 64 is arranged at the position where 7 is provided.

As shown in FIG. 4, in the microchannel group 62, a one-dimensional LD array element is provided for a plurality of microchannels 63 located at both ends in the optical axis direction (arrow X direction) of the YAG laser beam. 64 are not interposed, and these micro channels 63 are dummy channels 68. The reason will be described later.

As shown in FIGS. 2 and 3, on the inlet side and the outlet side of the parallel direct cooling structure from the microchannel group 62, a manifold 69 and a manifold 70 made of acrylic, which is an insulating material, are provided. Each is provided. Further, an LD element cooling water inlet 71 is provided at an upstream end of the inlet side manifold 69 vertically to the manifold 69, and at a downstream end of the outlet side manifold 70, perpendicular to the manifold 70. An LD element cooling water outlet 72 is provided.

That is, the cooling water flows from the LD element cooling water inlet 71 to the manifold 6 as indicated by arrows in FIGS.
After flowing into the manifold 69 in a direction perpendicular to the inflow direction, the water flows into the water channels 63a of the microchannels 63 of the microchannel group 62, and flows therethrough. After cooling each of the one-dimensional LD array elements 64, they flow out into the manifold 70 and merge, and further flow through the manifold 70 and are discharged from the LD element cooling water outlet 72.

The inlet side manifold 69 has two side surfaces 69.
The interval between c and 69d is composed of a diffusion section 69a extending from the LD element cooling water inlet 71 on the upstream side to the microchannel group 62 on the downstream side, and a parallel section 69b having the constant interval.

For this reason, the cooling water flowing into the manifold 69 from the LD element cooling water inlet 71 is diffused by the diffusion part 69a along the spread of both side surfaces 69c and 69d, and reaches the parallel part 69b. Thereafter, the cooling water flows in parallel at the parallel portion 69b.
In the vicinity of 9c and 69d, the flow velocity of the cooling water decreases due to friction with both side surfaces 69c and 69d, and boundary layers 73a and 73b are generated as shown by a two-dot chain line in FIG. , 73b are the microchannel group 62
Develop as you approach.

Since the flow velocity difference between the cooling water in these boundary layers 73a and 73b and the cooling water in other parts is large, when the one-dimensional LD array element 64 is cooled by these cooling waters, the primary ends of both ends are reduced. The temperature difference between the original LD array element 64 and the other one-dimensional LD array element 64 becomes very large. Therefore, the plurality of micro channels 63 located at both ends as described above are used as dummy channels 68 (see FIG. 4). That is, the boundary layer 73
In the region where the flow velocity of the cooling water is lower than the flow velocity of the main flow due to a and 73b, dummy micro-channels 63 in which the one-dimensional LD array element 64 is not provided are arranged, and flow through the water channels 63a of these micro-channels 63. The low-flow-rate cooling water does not contribute to the cooling of the one-dimensional LD array element 64.

The specific number of the micro channels 63 to be the dummy channels 68 is determined by the boundary layers 73a and 73.
The thickness is determined by the thickness of b (the width in the direction of arrow X in FIG. 2) and the thickness of one microchannel 63. For example, if the thickness of the boundary layers 73a and 73b at the entrance of the water channel 63a is 4 mm and the thickness of one microchannel 63 is 3 mm, the two microchannels 63 at both ends are replaced with the dummy channel 68. I just need.

Further, rectifying plates 74 and 75 and a rectifying plate 76 are provided on the diffusion portion 69a and the parallel portion 69b of the manifold 69 in order to make the flow rate of the cooling water uniform. In the manifold 69, the main flow at the center is fast, and the flow at both sides has a slow flow velocity distribution. Therefore, the flow velocity distribution in the manifold 69 is made uniform, and as shown by a two-dot chain line in FIG.
The current plates 74, 75, 76 are provided in order to make the current uniform. In the flow velocity distribution 110, the horizontal direction in FIG. 2 is the microchannel position, and the vertical direction in FIG. 2 is the flow velocity.

As shown in FIG. 6, the straightening plate 76 of the parallel portion 69b is a rectangular straight plate made of acrylic, and is disposed so as to be orthogonal to the flow of the cooling water in the parallel portion 69b. In addition, a large number of punch holes 76a are formed in a perforated plate formed in a staggered lattice shape, and the pitch and size of these holes 76a are appropriately adjusted, so that a moderate pressure drop is generated between the main flow and the flow on both sides. Is caused. That is, the center portion of the current plate 76 does not easily flow, and the side portions thereof easily flow.

The rectifying plates 74 and 75 of the diffusion section 69a are formed by bending a rectangular plate made of acrylic with a curvature corresponding to the spread of the diffusion section 69a, and are formed so as to protrude downstream. Along with the rectifying plate 76, a large number of holes 74a and 75a are formed in a perforated plate formed in a staggered lattice shape, and these holes 74a and 75a are formed.
The pitch and size of “a” are appropriately adjusted so that an appropriate pressure loss occurs between the main flow and the flows on both sides.
That is, the center portions of the flow straightening plates 74 and 75 are hard to flow, and the side portions are easy to flow. In addition, as described above, the current plate 7
The reason why the curved portions 4 and 75 are curved is that the condition is the same by making the cooling water orthogonal to the streamline direction of the cooling water diffused along the spreading portion 69a at any position.

The current plates 74, 75, 76 are not limited to perforated plates, but may be meshes.

As shown in FIG. 2, the outlet-side manifold 70 has a contraction portion 70a in which the distance between both side surfaces 70c and 70d is reduced toward the LD element cooling water outlet 72 on the downstream side.
And the microchannel group 62 (microchannel 6
3) (see FIG. 3).
The interval is provided as a parallel section 70b provided as a running section leading to a.

On the other hand, as shown in FIG. 7, a slab holder 80 and a transmission plate
Are provided.

The slab holder 80 is formed by combining two metal plate-like members 80a and 80b, and holds a slab-type YAG crystal 82 inserted at the center thereof. The transmission plate holder 81 is a metal plate-like member and is provided in a pair on both sides of the slab holder 80, and holds a transmission plate (quartz plate) 83 inserted in the center of each. Then, the pair of transmission plate holders 81 are integrally connected to each other while sandwiching the slab holder 80 via an O-ring 84 to form the slab holder portion 54.

Two-dimensional LD array elements 61 are located on the left and right sides of the slab type YAG crystal 82 in FIG. 7, and the semiconductor laser oscillated from each one-dimensional LD array element 64 of these two-dimensional LD array elements 61. The beam 85 is transmitted through the transmission plate 83 to pass through both sides 82 of the slab type YAG crystal 82.
a, 82b.

In order to make the optical axis of the excitation source LD device 56 and the optical axis of the slab type YAG crystal 82 coincide with each other and make them orthogonal to each other, the pin hole 104 shown in FIG.
4 are provided through the manifolds 69 and 70 on both sides, and four pins 105 are inserted into these pin holes 104 as shown in FIG. Therefore, the optical axis of the excitation source LD device 56 and the slab type YAG crystal 8
The two optical axes can be surely and easily matched and orthogonalized.

As shown in FIG. 7, the irradiation width of the semiconductor laser beam 85 and the side surface 8 of the slab type YAG crystal 82
The one-dimensional LD array element 64 (two-dimensional LD array element 61) and the slab type Y
The distance x from the AG crystal 82 is adjusted. That is, the semiconductor laser beam 85 has a relatively large divergence angle (10 to 20).
°), and its width increases as it propagates. For this reason, the width (irradiation width) of the semiconductor laser beam 85 at the position of the side surfaces 82a and 82b
The distance x between the one-dimensional LD array element 64 and the slab-type YAG crystal 82 is adjusted so as to match the widths of a and 82b.

Alternatively, as shown in FIG. 8, a collimating lens (cylindrical lens) 111 is provided between the one-dimensional LD array element 64 (two-dimensional LD array element 61) and the slab type YAG crystal 82, and the collimating lens
In step 1, the spread of the semiconductor laser beam 85 may be suppressed so that the irradiation width of the semiconductor laser beam 85 and the widths of the side surfaces 82a and 82b of the slab-type YAG crystal 82 may be matched.

However, the divergence angle of the semiconductor laser beam for each LD element varies, and the divergence angle is relatively large at 10 to 20 °.
Semiconductor laser beam 8 oscillated from D array element 64
5 and the side surfaces 82a, 8 of the slab type YAG crystal 82.
It is difficult to completely match the width of the one-dimensional LD array element 64 with the width of 2b.
In the D array element 64, the irradiation width of the semiconductor laser beam 85 is slightly larger than the width of the side surfaces 82a and 82b. Therefore, in this state, the semiconductor laser beam 8
A part of 5 deviates from the side surfaces 82a and 82b and does not contribute to the excitation of the YAG laser medium, and the excitation efficiency is reduced.

Therefore, as shown in FIG. 7, the semiconductor laser beam 85 is applied to the side surfaces 82a, 8a of the slab type YAG crystal 82.
A reflecting surface 87 is provided in the propagation optical path before the light is irradiated to the second laser beam 2b, and a part of the semiconductor laser beam 85, which is deviated from the side surfaces 82a and 82b due to the spread of the semiconductor laser beam 85, is used by the reflecting surface 87. To reflect light to The reflecting surface 87 is a part of the O-ring presser 88, and the inner peripheral surface of the O-ring presser 88 is polished to form the reflecting surface 87.

Further, the reflection surface 87 (that is, the O-ring retainer 8)
8) is provided so as to surround the periphery of the slab type YAG crystal 82. As shown in FIG. 4, both sides of the slab type YAG crystal 82 in the longitudinal direction (arrow X direction) are provided.
A part of the semiconductor laser beam 85 deviating in the longitudinal direction from the side surfaces 82a and 82b of the AG crystal 82 is transferred to the side surfaces 82a and 82b.
82b.

By the way, as shown in FIG.
The irradiation width W1 of the semiconductor laser beam 85 is reduced by reducing the distance between the AG crystal 82 and the two-dimensional LD array element 61 or by condensing the semiconductor laser beam 85 with a lens.
If the width W2 of the side surfaces 82a and 82b of the AG crystal 82 is smaller than the width W2, all of the semiconductor laser beam 85 can be transmitted.
Although it is possible to irradiate the laser beam 82b, the quality of the YAG laser beam is reduced in such a case.

That is, when the semiconductor laser beam 85 is applied to the entire side surfaces 82a and 82b of the slab type YAG crystal 82, the entire side surface width is excited to generate heat.
As shown in FIG. 10A, the temperature distribution in the lateral width direction (the horizontal direction in FIG. 10) of the slab-type YAG crystal 82 becomes uniform, and as shown in FIG. Rate distribution. On the other hand, when the irradiation width of the semiconductor laser beam 85 is smaller than the widths of the side surfaces 82a and 82b, both ends in the side surface width direction are not excited and do not generate heat. Thus, the temperature distribution does not become uniform in the lateral width direction, and the refractive index distribution does not become uniform in the lateral width direction as shown in FIG. Therefore, in this case, the thermal lens optical compensation by the zigzag optical path propagation becomes insufficient, and the quality of the YAG laser beam deteriorates.

For this reason, it is necessary to irradiate the semiconductor laser beam 85 over the entire lateral width of the slab type YAG crystal 82. Therefore, as described above, the irradiation width of the semiconductor laser beam 85 and the side surfaces 82a and 82b of the slab type YAG crystal 82
And the slab type YAG
A part of the semiconductor laser beam 85 deviating from the side surfaces 82a, 82b of the crystal 82 is reflected by the reflection surface 87.
2b.

As shown in FIG. 7, a transmission plate 83 is provided in a propagation optical path until the semiconductor laser beam 85 oscillated from each one-dimensional LD array element 64 is irradiated on the slab type YAG crystal 82. And the transmission plate 83 and the slab type Y
A water passage 90 is formed between the side surfaces 82a and 82b of the AG crystal 82. The channel 90 is configured such that the cross-sectional area of the channel is the smallest in the channel system.
The water channel width is adjusted (for example, set to about 1 mm) so that the flow state of the cooling water flowing through 0 becomes turbulent, and the flow velocity is adjusted. The water channel system includes a transmission plate holder 81, a transmission plate 83, a slab type YAG crystal 82, and a slab holder 80.
And water channels 90, 91 and 92.

More specifically, as shown in FIGS. 14 to 17, a rectangular hole 81a for accommodating and holding the transmission plate 83 is formed in the center of the transmission plate holder 81. On both sides of 81a, a concave portion 8 is formed along the hole 81a.
1b and 81c are formed respectively.
An inflow hole 81d and an outflow hole 81e are formed at ends of 1b and 81c, respectively. And, as shown in FIG.
Water passages 91 and 92 are respectively formed by the concave portions 81 b and 81 c of the transmission plate holder 81 and the side surfaces of the slab holder 80.

On the other hand, as shown in FIG. 2, a slab crystal cooling water inlet 94 is provided on the right side of the upstream side of the outlet side manifold 70 of the excitation source LD device 56, and on the left side of the downstream side of the inlet side manifold 69. A slab crystal cooling water outlet 95 is provided. 12, the slab crystal cooling water inlet 94 communicates with the inflow hole 81d of the slab holder 81, and as shown in FIG.
5 communicates with the outflow hole 81e of the slab holder 81.

Therefore, as indicated by arrows in FIG. 7, the cooling water flowing from the slab crystal cooling water inlet 94 (see FIG. 3) flows through the water channel 91, the water channel 90, and the water channel 92 in this order, and It is discharged from the outlet 95 (see FIG. 3). Note that, on one side surface 82a side and the other side surface 82b side of the slab type YAG crystal 82, a slab crystal cooling water inlet 94 and a slab crystal cooling water outlet 95 are provided in reverse as shown in FIG. The flow direction of the cooling water is reversed as shown by the arrow in FIG.

[0086] In this waterway system, as described above, the waterway 90 is configured to have the smallest flow passage cross-sectional area. This is for increasing the heat transfer rate from the slab type YAG crystal 82 to the cooling water by making the flow rate of the cooling water in the water channel 90 the highest. Further, the channel width of the channel 90 is set so that the flow state of the cooling water flowing through the channel 90 becomes turbulent as described above. This is because the rate is much higher.

As shown in FIG. 19, the transmission plate 83 is formed in a rectangular shape, and the contact surface 83 having a slope structure is provided at both longitudinal ends of the back surface (the surface on the slab type YAG crystal side).
a, 83b are formed. On the other hand, as shown in FIG. 18, contact surfaces 81f and 81g having a slope structure are formed at both ends in the longitudinal direction of the periphery of the hole 81a of the transmission plate holder 81. Then, by bringing the contact surfaces 83a and 83b of the transmission plate 83 into surface contact with the contact surfaces 81f and 81g of the transmission plate holder 81, the vertical position of the transmission plate 83 in FIG. Transmission plate 83 and slab type YA
The distance from the G crystal 82) is accurately maintained at, for example, 1 mm (see FIG. 13).

When the sealing member such as an O-ring is interposed on the back surface of the transmission plate 83 and is supported by the transmission plate holder 81, the sealing member is deformed to accurately hold the width of the water passage 90. This is because they cannot. If the width of the channel 90 cannot be accurately maintained, an imbalance occurs in the cooling of the slab type YAG crystal 82 in each part of the channel 90,
As a result, the temperature distribution in the slab type YAG crystal 82 is affected, and the quality of the YAG laser beam is reduced. Therefore, in order to prevent such a problem, the transmission plate 83 and the transmission plate holder 81 are brought into surface contact as described above.

Further, as shown in FIG.
The contact surfaces 83a and 83 are provided only on both ends in the longitudinal direction.
b is formed, and no contact surface is formed in other portions. Further, as shown in FIG.
The contact surface 81 is also provided only at the peripheral edge of the hole 81 at both ends in the longitudinal direction.
f, 81 g are formed, and the contact surface is not formed in other portions. That is, the transmission plate 83 is supported by the transmission plate holder 81 only at the contact surfaces 83a and 83b at both ends in the longitudinal direction.

This is because the flow of the cooling water in the water channel 90 (see FIGS. 7 and 13) is not affected. That is, as shown by an arrow in FIG. 7 or FIG.
0, the cooling water flows in the lateral width direction of the transmission plate 83. Therefore, when the cooling water is formed to be in contact with the transmission plate holder 81 by forming a contact surface in the lateral width direction of the transmission plate 83, Then, a step is formed in the surface contact portion, and the flow of the cooling water is disturbed. For this reason, as described above, the transmission plate 83 is supported in contact with the contact surfaces 81f and 81g of the transmission plate holder 81 only at the contact surfaces 83a and 83b at both ends in the longitudinal direction which do not affect the flow of the cooling water. Is configured.

Further, as shown in FIG.
The four corners 83c, 83d, 83e, 83f of the third are provided with a curvature for mounting an O-ring, and an O-ring 97 is mounted all around the transmission plate 83 as shown in FIG. 7 or FIG. . On the other hand, as shown in FIG.
The contact surface 81h with the O-ring 97 has a slope structure. Then, the O-ring 97 between the entire periphery of the transmission plate 83 and the transmission plate holder 81 is pressed and crushed by an O-ring presser 88 fixed to the periphery of the hole 81a of the transmission plate holder 81 by bolts. A sealing structure for cooling water flowing through the water channel 90 is formed in close contact with the plate holder 81 and the transmission plate 83. The O-ring presser 88 presses the O-ring 97 at the same time as the O-ring 97 is pressed.

As shown in FIG. 7, the surface of the transmission plate 83 on the excitation source LD device side (two-dimensional LD array element side)
An anti-reflection coating film (dielectric multilayer film) 93 corresponding to the wavelength band of the semiconductor laser beam 85 is provided. On the other hand, the surface on the slab type YAG crystal side of the transmission plate 83 is not provided with an anti-reflection coating film.

The surface of the transmission plate 83 on the excitation source LD device side is in contact with air, and the air and the transmission plate 83 have different refractive indexes. Therefore, in this state, the semiconductor laser beam 85 is
3 is reflected on the surface on the side of the excitation source LD device, so that the side surfaces 82a and 82b of the slab type YAG crystal 82 are not irradiated, or return directly to the excitation source LD device side and adversely affect the excitation source LD device 56. .

Therefore, as described above, the anti-reflection coating film 93 is formed on the surface of the transmission plate 83 on the side of the excitation source LD device so as not to reflect the semiconductor laser beam 85. On the other hand, the surface of the transmission plate 83 on the slab type YAG crystal side is in contact with the cooling water, and since the refractive index of water and the transmission plate 83 is close, the semiconductor laser beam 85 is not reflected on this surface. There is no need to apply a reflective coating film.

As shown in FIG. 7, a slab type YAG
Both end faces 82 in the lateral width direction (vertical direction in FIG. 7) of crystal 82
Seal members 86a and 86b are provided on c and 82d. Specifically, the slab type YAG crystal 82 with the sealing members 86a, 86b attached to both end surfaces 82c, 82d is inserted into the center of the slab holder 80, and then the spacer thin plates 96a, 96b are attached to the sealing member 86.
a, 86b and the slab holder 80, the seal members 86a, 86b are inserted into the slab type YAG.
The structure is such that the sealing property is improved by being in close contact with the crystal 82 and the slab holder 80, and the attachment and detachment of the sealing members 86a and 86b are easy.

The side surface 8 of the slab-type YAG crystal insertion portion of one of the plate members 80a constituting the slab holder 80 is provided.
0a-1 has a slope structure as shown by a dashed line in FIG. 7, and the side surface 80b-1 of the slab-type YAG crystal insertion portion of the plate-like member 80b as the other lid constituting the slab holder 80 also has As shown by a dashed line in FIG. 7, when the two plate-like members 80a and 80b are combined as a slope structure, the sealing members 86a and 86b are attached to the side surfaces 80a-1 and 80a-1.
Slab type YAG by tightening to 80b-1
The structure may be such that the sealing function is exerted by closely contacting the crystal 82 and the slab holder 80. Also in this case, the ease of attachment and detachment is maintained.

The sealing members 86a and 86b seal the cooling water flowing through the water channel 90 and have a slab type YA.
A semi-transparent seal made of silicon is used as a material that insulates both end surfaces 82c and 82d of the G crystal 82 and does not absorb the semiconductor laser beam 85 and generate heat (that is, reflect the semiconductor laser beam 85). A member is used.

If the seal members 86a and 86b are black members or the like and absorb heat by absorbing the semiconductor laser beam 85, the heat generated by the seal members 86a and 86b is used.
6 may be melted, and further adversely affect the temperature distribution of the slab type YAG crystal 82.
That is, the temperature distribution in the side surface width direction of the slab type YAG crystal 82 changes and becomes non-uniform.

As described above, in the slab type YAG crystal 82, light propagates in the longitudinal direction (the direction perpendicular to the plane of FIG. 7) while reflecting in the thickness direction (horizontal direction in FIG. 7) while reflecting in a zigzag manner. Since optical compensation is performed, if the temperature distribution in the lateral width direction changes and becomes non-uniform, sufficient thermal lens optical compensation cannot be performed.

For this reason, it is necessary to select the seal members 86a and 86b which do not generate heat by absorbing the semiconductor laser beam 85. Further, it is not preferable that heat is released from both end faces 82c and 82d of the slab type YAG crystal 82 for the above reason. For this reason, both end faces 8
It is necessary to insulate the 2c and 82d sides with seal members 86a and 86b.

Further, as shown in FIG.
Non-irradiation regions (non-excitation regions) 82e and 82f where the semiconductor laser beam 85 oscillated from the excitation source LD device 56 is not irradiated are located at both ends in the longitudinal direction (the direction of the arrow X) of the crystal 82.
It has become. The non-irradiated areas 82e and 82f generate slab type YAG due to heat generated by the irradiation of the semiconductor laser beam 85.
When the crystal 82 extends in the longitudinal direction, it is a region provided to extend straight in the longitudinal direction without bending in the thickness direction (see FIG. 27B). This region is at least 15% of the entire length of the type YAG crystal 82. That is, the non-irradiation areas 82e and 82f
L2 is 15 times the total length L1 of the slab type YAG crystal 82.
%, And a portion of the length L3 other than the non-irradiation regions 82e and 82f is an irradiation region (excitation region) 82g.

The non-irradiated regions 82e and 82f may be of any size as long as they are 15% or more of the total length of the slab-type YAG crystal. Slab type YAG
It can be said that it is most desirable that the total length be 15% of the total crystal length.

Further, as shown in FIG.
At both ends of 00, a partially transmitting output mirror 101a and a total reflection mirror 101b constituting the resonator 101 are installed, and the apparatus body 52 is installed between the pair of reflection mirrors 101a and 101b. At this time, it is necessary to make the optical axis of the resonator 101 coincide with the optical axis of the slab type YAG crystal 82 provided in the apparatus main body 52.

For this reason, as shown in FIG. 7, two pin holes 102 are provided at the lower end of the slab holder 54, and the apparatus main body 52 is attached to the optical axis adjusting table 100 as shown in FIG. At this time, the optical axis of the resonator 101 and the slab-type YAG
The optical axis of the crystal 82 can be surely and easily matched.

<Operation / Effect> According to the LD-pumped slab YAG laser device 51 according to the present embodiment, the following operation / effect can be obtained.

(1) By adjusting the distance x between the one-dimensional LD array element 64 and the slab type YAG crystal 82, the excitation source LD
Since the irradiation width of the semiconductor laser beam 85 oscillated from the device 56 and the width of the side surfaces 82a and 82b of the slab type YAG crystal 82 are made to match, the semiconductor laser beam 85 is formed over the entire side surface width of the slab type YAG crystal 82. To excite the entire side width. For this reason,
The side surface width direction of the slab type YAG crystal 82 has a uniform temperature distribution and a uniform refractive index distribution. Therefore, in the slab type YAG crystal 82, the thermal lens optical compensation by the zigzag optical path propagation is sufficiently performed, and the quality of the YAG laser beam is improved.

(2) One-dimensional LD array element 64
Lens 1 between the slab type YAG crystal 82 and
11 and the irradiation width of the semiconductor laser beam 85 oscillated from the excitation source LD device 56 and the slab type YAG crystal 8
Also in the case where the widths of the two side surfaces 82a and 82b coincide with each other, similarly to the above, the semiconductor laser beam 85 is irradiated on the entire side surface width of the slab type YAG crystal 82 to excite the entire side surface width. In other words, since the side surface width direction of the slab type YAG crystal 82 has a uniform temperature distribution and a uniform refractive index distribution, the slab type YAG crystal 82 has sufficient thermal lens optical compensation by zigzag optical path propagation. Thus, the quality of the YAG laser beam is improved.

(3) Further, a reflection surface 87 is provided in the propagation optical path until the semiconductor laser beam 85 oscillated from the excitation source LD device 56 is irradiated on the side surfaces 82a and 82b of the slab type YAG crystal 82. Since the reflecting surface 87 is configured to reflect a part of the semiconductor laser beam 85 which is deviated from the side surfaces 82a and 82b due to the spread of the semiconductor laser beam 85 to the side surfaces 82a and 82b, all the semiconductor laser beams 85 are YAG laser. This can contribute to the excitation of the medium, and the output of the LD-pumped slab YAG laser device 51 is improved.

(4) Since the reflection plate 83 is provided on the surface of the transmission plate 83 facing the excitation source LD device,
Even if the transmission plate 83 and the air in contact with the surface of the transmission plate 83 on the side of the excitation source LD device have different refractive indexes, the semiconductor laser beam 85 is reflected by the surface of the transmission plate 83 on the side of the excitation source LD device. The slab type YAG crystal 82 is irradiated through the transmission plate 83 without being transmitted. Therefore, the excitation efficiency of the YAG laser medium is improved. Further, there is no possibility that the semiconductor laser beam 85 returns directly to the excitation source LD device 56 and adversely affects the excitation source LD device 56.

(5) At least 15% of the entire length of the slab type YAG crystal 82 at both ends in the longitudinal direction of the slab type YAG crystal 82 is not irradiated with the semiconductor laser beam 85 oscillated from the excitation source LD device 56. The slab type YAG crystal 82
When elongates in the longitudinal direction due to heat generated by the irradiation of the semiconductor laser beam 85, it elongates straight in the longitudinal direction without bending in the thickness direction. Therefore, the quality of the YAG laser beam can be improved.

According to the LD-pumped slab YAG laser device 51 according to the present embodiment, the following operation and effects can be further obtained.

(6) A section until the flow of the cooling water flowing into the water channel 63a of each of the microchannels 63 constituting the microchannel group 62 is set as the approach section 67, and the two-dimensional section is provided at the position where the approach section 67 is provided. Since each one-dimensional LD array element 64 constituting the LD array element 61 is arranged, all of these one-dimensional LD array elements 6
4 will be cooled by the stable and uniform flow of cooling water.

Thus, each one-dimensional LD array element 64 can be cooled uniformly, and each one-dimensional LD array element 6 can be cooled.
No. 4 has a uniform temperature and oscillation characteristics. Therefore, by irradiating the slab type YAG crystal 82 with the semiconductor laser beam 85 oscillated from the one-dimensional LD array element 64, the excitation efficiency of the YAG laser medium is improved,
The output of the LD pumped slab YAG laser device 51 is improved.

(7) The manifold 69 on the inlet side
A dummy channel 68 in which the one-dimensional LD array element 64 is not provided is arranged in a region where the flow velocity of the cooling water is lower than the main flow velocity due to the boundary layers 73a, b generated on both side surfaces 69c, 69d of the parallel portion 69b. Therefore, the low-velocity cooling water in the boundary layers 73a and 73b flows through the water channel 63a of the dummy channel 68, and the one-dimensional LD array element 6
4. Only cooling water other than the boundary layers 73a and 73b flows through the water channel 63a of each microchannel 63 provided with the one-dimensional LD array element 64 to cool each one-dimensional LD array element 64 without being involved in the cooling of the four. become.

Therefore, the flow rate of the cooling water for cooling each one-dimensional LD array element 64 is made more uniform, and as a result, each one-dimensional LD array element 64 has a more uniform temperature. More oscillation characteristics. Therefore, YA
The pumping efficiency of the G laser medium is further improved, and the output of the LD pumped slab YAG laser device 51 is further improved.

When the area corresponding to the boundary layers 73a and 73b is simply closed without providing the dummy channel 63, the water channel 63a of the microchannel 63 adjacent to this area is connected to the boundary layer 73a and 73b. Cooling water flows in, and eventually, each one-dimensional LD array element 64
Cannot be cooled uniformly. Therefore, it can be seen from this that providing the dummy channels 68 in the regions corresponding to the boundary layers 73a and 73b is very effective.

(8) The manifold 69 on the inlet side
Since the rectifier plates 74, 75, 76 are provided in the, the flow velocity distribution of the cooling water flowing in the manifold 69 can be made uniform.

For this reason, each microchannel 6
The flow velocity distribution of the cooling water flowing through the third water passage 63a can be made uniform, and the temperature of each one-dimensional LD array element 64 is made uniform, so that the oscillation characteristics become uniform. Therefore, the pumping efficiency of the YAG laser medium is further improved, and the output of the LD pumped slab YAG laser device 51 is further improved.

As shown in FIG. 21, as a result of a cooling water flow velocity distribution test in the manifold 69, when the rectifying plate is not provided in the manifold 69, the main flow at the center and the flow at both sides are different. Was large (see FIG. 21).
White squares in the square), rectifying plates 74 and 7 on manifold 69
When 5,76 was provided, the flow velocity difference was within ± 3% of the average flow velocity, and the flow velocity distribution became uniform (FIG. 2).
Black square in 1). From this, the current plates 74, 75,
The effectiveness of 76 was confirmed.

(9) In addition, the rectifying plates 74 and 75 are provided not only on the parallel portions 69b of the manifold 69 but also on the diffusion portions 69a.
, The three rectifying plates 74, 75, 76
Can make the flow velocity distribution uniform. That is, the parallel portion 6
Although it is necessary to provide a rectifying plate at 9b, if a rectifying plate is provided only at the parallel portion 69b, the flow velocity distribution cannot be made uniform unless more rectifying plates are provided. By providing the rectifying plate also in the diffusion portion 69a where the flow velocity difference from the flow is not so large, the flow velocity distribution can be made uniform with a small number of rectifying plates.

(10) The manifold 6 on the inlet side
9 is provided so that the flow direction of the cooling water into the cooling water 9 is orthogonal to the flow direction of the cooling water flowing through the manifold 69 toward the microchannel 63, and the two directions are the same. Compared to the case of the direction (see FIG. 22), the velocity component of the main flow can be reduced, and the flow velocity difference between the main flow and the flow on both sides can be reduced.

(11) In addition, the outlet side manifold 7
0, the parallel portion 70b is provided as a run-up section until the cooling water that has exited the water channel 63a of each microchannel 63 reaches the contraction portion 70a, so that the cooling water flowing through the water channel 63a of each microchannel 63 is provided. The flow velocity distribution can be maintained uniform. That is, if the contraction part 70a is located too close to the outlet of the water passage 63a, the flow velocity distribution is changed by affecting the flow velocity of the cooling water flowing through each water passage 63a. On the other hand, if the parallel section 70b is provided as the approach section, there is no change in the flow velocity distribution, and
The flow velocity distribution of the cooling water flowing through a can be maintained uniform.

(12) The slab type YAG crystal 82
Sealing members 86a and 86b that seal the cooling water, insulate both end surfaces 82c and 82d, and absorb the semiconductor laser beam 85 and do not generate heat are provided on both end surfaces 82c and 82d in the side surface width direction. Therefore, the sealing member 86
At the same time as sealing the cooling water by a and 86b, the temperature distribution of the slab type YAG crystal 82 can be maintained in a state suitable for performing thermal lens optical compensation by zigzag optical path propagation. Therefore, the quality of the YAG laser beam is improved.

(13) Seal members 86a, 86
b and a thin plate 96 for a spacer
Since the sealing members 86a and 86b are inserted into the slab-type YAG crystal 82 and the slab holder 80 by inserting the sealing members 86a and 96b, the cooling water can be reliably sealed and the sealing members 86a and 86b can be attached and detached. Easy.

(14) The side surface 80a-1 of the slab-type YAG crystal insertion portion of one plate-like member 80a constituting the slab holder 80 has a slope structure, and serves as the other cover constituting the slab holder 80. The side surface 80b-1 of the slab-type YAG crystal insertion portion of the plate-shaped member 80b also has a slope structure, and when the two plate-shaped members 80a, 80b are combined, the sealing members 86a, 86b are connected to the side surfaces 80a-1, 80a.
Also, when the slab-type YAG crystal 82 and the slab holder 80 are configured to be in close contact with each other by tightening at 0b-1,
The cooling water can be reliably sealed, and the sealing members 86a and 86b can be easily attached and detached.

(15) The transmission plate 83 and the slab type Y
Since the flow path cross-sectional area of the water channel 90 formed between the side surfaces 82a and 82b of the AG crystal 82 is minimized in the water channel system, the cooling water flowing through the water channel system has the highest flow velocity in the water channel 90. In addition, the heat transfer coefficient from the slab type YAG crystal 82 to the cooling water is increased, and the cooling capacity of the slab type YAG crystal 82 is improved.

(16) By adjusting the flow width of the water channel 90 to adjust the flow rate of the cooling water,
Since the cooling water flow is configured to be turbulent, the heat transfer coefficient is significantly higher than in the case of laminar flow, and the cooling capacity of the slab type YAG crystal 82 is further improved.

(17) The slab type Y of the transmission plate 83
The surface on the AG crystal side is brought into surface contact with the transmission plate holder 81,
Since the configuration is such that the width of the water channel 90 is kept constant, the width of the water channel 90 can be always kept accurately (for example, about 1 mm) accurately. Therefore, there is no imbalance in cooling of the slab type YAG crystal 82 in each part of the water channel 90. For this reason, the side surfaces 82a and 82b of the slab type YAG crystal 82 are uniformly cooled, and the temperature distribution in the slab type YAG crystal 82 is maintained in a state suitable for performing thermal lens optical compensation by zigzag optical path propagation. As a result, the quality of the YAG laser beam is improved.

(18) Further, the corner of the transmission plate 83 is provided with a curvature capable of mounting an O-ring, and the O-ring 97 is mounted on the entire periphery of the transmission plate 83. Of the cooling water is formed by pressing the O-ring 97 between the entire periphery of the transmission plate 83 and the transmission plate holder 81 with the O-ring presser 88 to crush the O-ring 97. The cooling water can be reliably sealed by closely contacting the transmission plate 83 and the transmission plate holder 81.

In the present embodiment, the case of a YAG laser device has been described as an example. However, the present invention is not limited to this, and the present invention can be applied to other solid-state laser devices.

[0131]

As described above, the semiconductor laser-pumped slab solid-state laser device of the present invention uses the semiconductor laser device as a pump source and uses a slab-type crystal. In the slab solid-state laser device, 15% of the entire length of the slab-type crystal at both ends in the longitudinal direction of the slab-type crystal may be a non-irradiation region where the semiconductor laser beam emitted from the semiconductor laser device is not irradiated. Features.

Therefore, according to the semiconductor laser-pumped slab solid-state laser device of the present invention, a region of 15% of the entire length of the slab-type crystal at both ends in the longitudinal direction of the slab-type crystal is used for the semiconductor laser beam oscillated from the semiconductor laser device. When the slab-type crystal is extended in the longitudinal direction due to heat generated by the irradiation of the semiconductor laser beam, the slab-type crystal extends straight in the longitudinal direction without bending in the thickness direction. Therefore, the quality of the solid-state laser beam can be improved.

[0133]

[0134]

[0135]

[0136]

[0137]

[0138]

[0139]

[0140]

[Brief description of the drawings]

FIG. 1 shows an LD excitation slab YA according to an embodiment of the present invention.
FIG. 2 is a system diagram illustrating an overall configuration of a G laser device.

FIG. 2 is a side view showing a main part of the LD pumped slab YAG laser device, partially cut away (as viewed in the direction of arrow F in FIG. 3).

FIG. 3 is a sectional view taken along line AA of FIG. 2;

FIG. 4 is an enlarged cross-sectional view taken along line BB of FIG. 2;

FIG. 5 is an enlarged perspective view showing a main body of an excitation source LD device provided in the LD excitation slab YAG laser device.

FIG. 6 is an enlarged perspective view of a current plate provided in a manifold of the excitation source LD device.

FIG. 7 is an enlarged view illustrating a slab holder portion extracted from FIG. 3;

FIG. 8 is a cross-sectional view of a main part showing a configuration when a collimator lens is provided.

FIG. 9 is a slab type YAG in which the irradiation width of a semiconductor laser beam is
FIG. 4 is an explanatory diagram showing a state in which the width is smaller than a lateral width of a crystal.

FIG. 10 is an explanatory diagram showing a temperature distribution and a refractive index distribution in a slab type YAG crystal when a semiconductor laser beam is applied to the entire side surface width of the slab type YAG crystal.

FIG. 11 is a case where the irradiation width of the semiconductor laser beam is narrower than the side width of the slab type YAG crystal (in the case of condensing irradiation).
FIG. 3 is an explanatory diagram showing a temperature distribution and a refractive index distribution in a slab type YAG crystal of FIG.

FIG. 12 is an enlarged cross-sectional view taken along line DD of FIG. 2;

FIG. 13 is an enlarged view of a portion E in FIG. 4;

FIG. 14 is a front view of the transmission plate holder (a view in the direction of arrow F in FIG. 7).

FIG. 15 is a rear view of the transmission plate holder.

16 (a), (b), (c), and (d) are cross-sectional views taken along line GG, HH line, JJ line, and FIG. It is a K direction arrow view.

17A and 17B are a cross-sectional view taken along line LL and a line MM of FIG.

FIG. 18 is an enlarged view of an N1 part and an N2 part of FIG.

19 (a), (b) and (c) are front views of a transmission plate,
It is a side view and a back view.

FIG. 20 is a side view showing a state where the main body of the LD-excited slab YAG laser device is attached to an optical axis adjusting table.

FIG. 21 is an explanatory diagram showing a flow velocity distribution test result of cooling water flowing in the manifold.

FIG. 22 is a perspective view of a conventional excitation source LD device.

FIG. 23 is a process diagram illustrating a manufacturing process of the excitation source LD device.

FIG. 24 is a process chart showing a manufacturing process of the excitation source LD device.

FIG. 25 is an explanatory diagram showing an outline of a YAG laser device using a rod-type YAG crystal.

FIG. 26 is an explanatory diagram showing an outline of a YAG laser device using a slab type YAG crystal.

FIG. 27 is an explanatory diagram showing an outline of an LD pumped slab YAG laser device.

[Explanation of symbols]

 51 LD pumped slab YAG laser device 52 Device main body 53 Cooling water circulation system 54 Slab holder portion 56 Excitation source LD device 57 First cooling water loop 58 Second cooling water loop 59 Third cooling water loop 60 Temperature controlled cooling water circulator 61 2 Dimensional LD array element 62 Microchannel group 63 Microchannel 63a Water channel 64 One-dimensional LD array element 65 Excitation source LD device main body 66 Insulation material 67 Approaching section 68 Dummy channel 69 Manifold 69a Diffusion part 69b Parallel part 69c, 69d Side surface 70 manifold 70a Contraction part 70b Parallel part 70c, 70d Side surface 71 LD element cooling water inlet 72 LD element cooling water outlet 73a, 73b Boundary layer 74, 75, 76 Rectifying plate 74a, 75a, 76a Hole 80 Slab holder 80a, 80b Plate member 8 Transmission plate holder 81a Hole 81b, 81c Recess 81d Inflow hole 81e Outflow hole 81f, 81g Contact surface with transmission plate 81h Contact surface with O-ring 82 Slab type YAG crystal 82a, 82b Side surface 82c, 82d End surface 82e, 82f Non-irradiation area 83 Transmission plate 83a, 83b Contact surface with transmission plate holder 83c, 83d, 83e, 83f Angle 84 O-ring 85 Semiconductor laser beam 86a, 86b Sealing member 87 Reflecting surface 88 O-ring holder 90, 91, 92 Waterway 93 Non-reflective coating Film 94 Slab crystal cooling water inlet 95 Slab crystal cooling water outlet 96a, 96b Spacer thin plate 97 O-ring 100 Optical axis adjustment table 101 Resonator 101a Output mirror 101b Total reflection mirror 102, 104 Pin hole 105 Pin 111 Collimating lens

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takashi Akabane 1-1-1, Wadasaki-cho, Hyogo-ku, Kobe-shi, Hyogo Mitsubishi Heavy Industries, Ltd. Kobe Shipyard (72) Inventor Masahiro Okano Marunouchi, Chiyoda-ku, Tokyo No.5-1, Mitsubishi Heavy Industries, Ltd. (56) References JP-A-4-12577 (JP, A) JP-A-5-69963 (JP, U)

Claims (1)

(57) [Claims] 1. A semiconductor laser excitation slab solid state laser device using a semiconductor laser device as an excitation source and a slab-type crystals, 15% of the area of the total length of the longitudinal ends definitive said slab type crystal of the slab-type crystal A semiconductor laser-excited slab solid-state laser device, wherein the non-irradiation region is not irradiated with a semiconductor laser beam oscillated from the semiconductor laser device.