JPH0661550A - Solid-state laser device - Google Patents

Abstract

PURPOSE:To prevent the enclosure of a solid-state laser device and its peripheral structure from being irradiated with and damaged by stray light from the laser beam of the laser device so as to stabilize the operations and prolong the service life of the laser device. CONSTITUTION:A light shielding mechanisms 10 which blocks stray light rays 51 and 52 from a laser beam generated from the vicinity of the end face 1b of a slab-type laser medium 1 is provided on lamp terminal supporting bodies 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state laser device, and more particularly to a slab-type solid-state laser device, which has stable operation, improved beam quality, and long life.

[0002]

2. Description of the Related Art FIG. 5 shows, for example, Japanese Utility Model Laid-Open No. 61-142469.
FIG. 6 is a side sectional view showing a conventional solid-state laser device disclosed in Japanese Patent Publication No. In the figure, 1 is a pair of opposed flat surfaces 1a.
And a pair of side faces and a pair of end faces 1b through which the laser main beam enters and exits, a slab-type solid-state laser medium (hereinafter referred to as a slab), 2 is a lamp that optically excites the slab 1, and 3 is its excitation light. . Reference numerals 4a and 4b denote a pair of resonator mirrors disposed outside, and reference numeral 5 denotes a laser main beam emitted to the outside by the resonator mirrors. 6 is a slab refrigerant, and 7 is a sealing material for this refrigerant. Reference numeral 8 is a housing for holding the slab 1. Reference numerals 51 and 52 are reflected lights of the laser beam from the entrance / exit end surface 1b of the slab 1.

The slab 1 absorbs the excitation light 3 from the excitation lamp 2 and forms a population inversion. The energy of the population inversion is emitted from the outside of the medium as a laser main beam 5 propagating in a zigzag manner while repeating total internal reflection between a pair of opposed planes 1a of the slab 1 by a pair of resonator mirrors 4a and 4b arranged outside. Taken out. However, most of the excitation light energy absorbed by the slab 1 becomes thermal energy inside the slab 1, and finally flows into the refrigerant 6 filled in contact with the facing flat surface 1 a of the slab 1. At this time, in the slab thickness direction, a square temperature distribution with a high temperature at the center and a square refractive index distribution accompanying it are formed, but since the optical path of the laser main beam 5 inside the slab 1 is zigzag, The influence of the squared refractive index distribution is canceled out, and the laser main beam 5 is not distorted. The refrigerant 6 is sealed on the facing flat surface 1a of the slab 1 by a sealing material 7 so as not to leak to the outside. The sealing material 7 also serves as a support for the slab 1 on the housing 8.

Generally, the laser beam entrance / exit end surface 1b of the slab 1 is Brewster cut, but the laser main beam 5 is
It is configured to have low reflection and low loss. However, it is impossible to set the reflectance to 0, and the reflected light 51, 52 (stray light) from the side surface of the laser medium of the laser main beam 5 cannot be completely suppressed. In addition to the light 51 reflected to the external space, there are two types of light reflected on the end surface, that is, the light 52 reflected inside the slab 1 and then refracted at the slab 1 facing plane 1a and emitted to the external space.

[0005]

Since the conventional solid-state laser device is configured as described above, the reflected light 51, 52 (stray light) from the laser beam entrance / exit end face 1b of the slab 1 is stray light.
Cannot be completely suppressed, and these reflected lights 51,
There is a problem that 52 is irradiated to the laser housing 8 and the lamp terminal holder 9 attached to the laser housing 8 and is damaged. Even before the damage, outgas is generated from the irradiated areas of the reflected light 51, 52, and these fumes are not only good in the optical path of the laser main beam, but also reduce the beam quality and laser output, or near the slab end. There is a problem that fume adheres to and is polluted, and the slab is distorted due to the heating of the polluted portion, and the beam quality and the laser output are reduced.

The present invention has been made to solve the above-mentioned problems, and prevents damage to the laser housing and its accessories due to stray light from the laser beam, and prolongs the life of the laser beam. It is an object of the present invention to obtain a solid-state laser device which is stable in operation and which prevents deterioration in quality and output.

[0007]

A solid-state laser device according to the present invention comprises a light-shielding mechanism for shielding stray light of a laser beam generated near the laser beam entrance / exit end face of a slab type laser medium.

As the above-mentioned light-shielding mechanism, it is preferable to use a light-shielding material which has durability to the laser beam and absorbs it.

Alternatively, as the above-mentioned light-shielding mechanism, it is preferable to use a light-shielding material which has durability against a laser beam and reflects it.

Further, such a light shielding mechanism may be provided with a cooling means for the light shielding member.

Further, it is preferable to provide a device for generating a gas flow between the light shielding mechanism and the vicinity of the slab end and the optical path of the laser main beam.

[0012]

The mechanism for shielding the stray light of the laser beam in the present invention shields the stray light of the laser beam generated from the vicinity of the laser beam entrance / exit end face of the slab and prevents the laser housing and the parts attached thereto from being irradiated. To do.

Further, it has durability against a laser beam,
The light-shielding material that absorbs this prevents the stray light of the laser beam from irradiating the laser housing and the like, and also prevents the stray light of the laser beam from reflecting the stray light and re-irradiating the surrounding area.

Further, it has durability against a laser beam,
Moreover, the light-shielding material that reflects this prevents the stray light of the laser beam from irradiating the laser housing and the like, and also guides the stray light of the laser beam to the external absorber and the like, and prevents re-irradiation to the peripheral parts. .

Further, the means for cooling the light shielding member prevents heating of the light shielding member and prevents heating of the vicinity of the slab end portion and the surrounding structure due to heat conduction and heat radiation from the light shielding member.

Further, a mechanism for generating a gas flow between the light shielding member and the vicinity of the end of the slab and the optical path of the laser main beam is
Fume generated from the surface of the light shielding member by the gas flow is removed from the vicinity of the slab end surface.

[0017]

EXAMPLES Example 1. FIG. 1 is a side sectional view showing an embodiment of the present invention. The basic configuration of the laser medium such as pumping, cooling, support, and resonator is the same as that of the prior art shown in FIG. In the figure, reference numeral 1 is a slab type solid-state laser medium (hereinafter referred to as slab) having a pair of opposed flat surfaces 1a, a pair of side surfaces, and a pair of end surfaces 1b through which a laser main beam enters and exits, and 2 is a lamp for optically exciting the slab 1. Then, 3 is the excitation light. Reference numerals 4a and 4b denote a pair of resonator mirrors disposed outside, and reference numeral 5 denotes a laser main beam emitted to the outside by the resonator mirrors. 6 is a slab refrigerant, and 7 is a sealing material for this refrigerant. Reference numeral 8 is a housing for holding the slab 1. Reference numerals 51 and 52 denote reflected light from the end surface 1b of the slab 1. Reference numeral 10 denotes a light blocking member that blocks the end face reflected lights 51 and 52.

Next, the operation will be described. The slab 1 absorbs the excitation light 3 from the excitation lamp 2 and forms a population inversion. The energy of the population inversion is generated by the pair of resonator mirrors 4a and 4b arranged outside, so that the energy of the slab 1 facing each other is 1
The laser main beam 5 propagating in a zigzag shape while repeating total internal reflection between the pair of flat surfaces 1a is taken out of the medium. However, most of the excitation light energy absorbed by the slab 1 becomes thermal energy inside the slab 1, and finally flows into the refrigerant 6 filled in contact with the facing flat surface 1 a of the slab 1. At this time, in the slab thickness direction, a square temperature distribution with a high temperature in the central portion and a square refractive index distribution accompanying it are formed, but since the optical path of the laser main beam 2 inside the slab 1 is zigzag, The influence of the squared refractive index distribution is canceled out, and the laser main beam 2 is not distorted. The refrigerant 6 is sealed on the facing flat surface 1a of the slab 1 by a sealing material 7 so as not to leak to the outside. The sealing material 7 also serves as a support for the slab 1 on the housing 8.

Generally, the laser beam entrance / exit end face 1b of the slab 1 is Brewster-cut, but it is constructed so as to have low reflection and low loss with respect to the laser main beam 5 by being coated with an antireflection film. There is. However, it is impossible to set the reflectance to 0, and it is impossible to completely suppress the reflected lights 51 and 52 (stray light) from the end surface of the laser main beam 5. In addition to the light 51 that is reflected to the external space, there are two types of light, that is, the light 52 that is reflected inside the slab 1 and then refracted at the facing flat surface 1a of the slab 1 and emitted to the external space. In the conventional device, this end surface reflected light 5
From 1 and 52, the support 9 of the terminal of the excitation lamp 2 is irradiated and is damaged, or fumes are generated from the irradiation site, and there is a problem that it is only in the optical path of the laser main beam, and the beam quality and output are reduced. there were. In particular, since the support 9 of the terminal of the excitation lamp 2 needs to have electrical insulation, it is often the case that resin such as gelacon is used.
Even when laser oscillation of 0 to 200 W)
Problems such as melting due to 1, 52 (several W) and generation of fumes were remarkable.

Therefore, in this embodiment, a light shielding member 10 having durability against a laser beam is provided on the surface of the support 9 of the lamp terminal to shield the end face reflected lights 51 and 52 from each other.
Is prevented from irradiating. As the light shielding member 10, alumina ceramics, silica ceramics, or the like, which has durability against a laser beam and does not generate outgas, is suitable. If a material that absorbs a laser beam, such as aluminum that has been subjected to chloralumite treatment, is used as the light shielding member 10, the end face reflected lights 51 and 52 on the surface of the light shielding member 10 are used.
This is more effective because it can reduce the re-reflection of the laser beam and the irradiation and heating of the laser beam in the peripheral portion.

Example 2. In the above embodiment, the light blocking member 10
Has described the case of using a material having a relatively low reflectance and an absorptivity to the laser beam, but in the second embodiment shown in FIG. 2, the light shielding member 10 is made of a substance having a high reflectance to the laser beam. To use. Specifically, the light shielding member 10 is made of a metal such as stainless steel, aluminum, or copper, and its surface 10a is coated with a high-reflectance metal such as gold, silver, or aluminum to form a mirror surface. The reflection directions 51 and 52 from the slab end face 1b are reflected on the surface 10a, guided to the external damper 11, and absorbed. If the surface 10a of the light shielding member 10 is a mirror surface, diffuse reflection from the light shielding member surface 10a can be reduced and the reflection direction can be specified to the external space. Therefore, the end surface reflected light 51 reflected by the light shielding member surface 10a,
It is possible to greatly reduce the re-irradiation heating of the laser housing 8, the lamp terminal retainer 9, the vicinity of the end portion of the slab 1 and the like by 52.
Further, since the light shielding member 10 has a high reflectance with respect to the laser beam and little absorption, it is possible to reduce heating of the light shielding member 10 itself and generation of heat radiation accompanying it, which is a structure near the end of the slab 1 and its peripheral structure. It also has an effect of reducing heating.

Example 3. In the third embodiment shown in FIG.
A flow path 10b of cooling water is provided inside the light shielding member 10 to perform water cooling to prevent heating due to absorption of light reflected by the end surface of the light shielding member 10. Especially when high-power transmission of several 100 w or more is performed,
The temperature rise due to the absorption of the laser beam of the light blocking member 10 is also high, and this heat may heat and distort the end portion of the slab 1 via the structure such as the housing 8 and the atmosphere, thereby performing a more stable laser operation. Therefore, it is effective to cool the light shielding member 10 with water.

Example 4. In the fourth embodiment shown in FIG. 4,
A gas ejection port 12 is provided on the side surface 1c of the slab end portion, and pure gas is caused to flow between the light shielding member 10 and the vicinity of the slab end portion and the optical path of the laser main beam. 4A is a side sectional view, and FIG. 4B is a lateral sectional view taken along the line AA of FIG. When a material having durability with respect to the laser beam such as ceramics or metal is used as the light shielding member 10, the material itself rarely generates gas even when the laser beam is irradiated. However, dust in the atmosphere actually adheres to the surface, and these generate fumes by laser beam irradiation. When the fumes enter the optical path of the laser beam 5, not only the output is reduced, but also temperature unevenness occurs in the optical path, which causes a problem such as distortion of the beam. Also, the fume is the slab end face 1b.
Or, when the slab 1 adheres to the opposing plane 1a, the slab 1 itself is locally heated due to the absorption of the adhered laser beam, and the beam is distorted, burned, or, in the worst case, damaged. There's a problem. Therefore, in this embodiment, a pure gas flow is generated between the light shielding member 10 and the vicinity of the slab end portion and the optical path of the laser main beam, and the fumes generated from the surface of the light shielding member form the optical path of the laser main beam 5 and the slab. It is to prevent it from arriving near the end face. As a gas to be used, an inert gas that does not absorb a laser beam is desirable, and nitrogen, helium, dry air or the like is suitable. The generation of the gas flow has the effect of cooling the light shielding member and the vicinity of the end of the slab in addition to the removal of the fumes.

In the above-described series of embodiments, the light shielding member 10 has been described as a component independent of the laser housing. However, the laser housing 8 itself may have a function as a light shielding material.

Further, the light shielding member 10 may be installed at a position other than the position shown in the above embodiment so that the peripheral members are shielded from the stray light of the laser beam.

Further, as the light-shielding mechanism, one without the damper 11 in FIG. 2 or one having an integrated structure in which the light-shielding member 10 has the reflecting surface 10a and the portion for absorbing the reflected light from the reflecting surface 10a. Good.

[0027]

As described above, according to the present invention, since the mechanism for shielding the stray light of the laser beam generated from the vicinity of the laser beam entrance / exit end face of the slab type laser medium is provided, the stray light of the laser beam is not generated by the laser housing. It is possible to irradiate the peripheral structure and the peripheral structure and prevent the structure from being damaged, and it is possible to achieve stable operation and a long life of the laser.

If a light shielding material having durability and absorbing the laser beam is used as a mechanism for shielding the stray light of the laser beam, the stray light of the laser beam directly irradiates the surrounding structure. It is possible to prevent the stray light of the laser beam from being reflected on the surface of the light shielding member and to irradiate and heat the vicinity of the slab end portion and the peripheral structure, and it is possible to realize a stable operation and a long life of the laser.

Further, as a mechanism for shielding the stray light of the laser beam, if a light shielding material having durability against the laser beam and reflecting the same is used, the stray light of the laser beam directly irradiates the surrounding structure. In addition, it is possible to guide stray light reflected from the surface of the light shielding member to an external absorber, etc., and prevent re-irradiation and heating of the slab edge and its surrounding structures, thus achieving stable operation and longer life of the laser. it can.

Further, since the means for cooling the light shielding member is provided, heating of the light shielding member itself due to absorption of the laser beam can be reduced, and heat conduction and heat radiation from the light shielding member causes the vicinity of the end of the slab and surrounding structures. By suppressing heating, stable operation and longer life of the laser can be realized.

Furthermore, since the gas flow is generated between the light shielding member and the vicinity of the slab end portion and the optical path of the laser main beam, the fumes generated from the surface of the light shielding member are generated from the vicinity of the slab end portion by the gas flow. It can be removed and stable operation of the laser and longer life can be realized.

[Brief description of drawings]

FIG. 1 is a side sectional view showing a solid-state laser device according to a first embodiment of the present invention.

FIG. 2 is a side sectional view showing a solid-state laser device according to a second embodiment of the present invention.

FIG. 3 is a side sectional view showing a solid-state laser device according to Embodiment 3 of the present invention.

FIG. 4 is a side sectional view and a lateral sectional view showing a solid-state laser device according to a fourth embodiment of the present invention.

FIG. 5 is a side sectional view showing a conventional solid-state laser device.

[Explanation of symbols]

 1 Slab-type laser medium 1a Plane 1b End face 1c Side face 2 Lamp 5 Laser main beam 6 Refrigerant 10 Light blocking member 10b Flow path 12 Gas jet 13 Gas flow 51 Reflected light 52 Reflected light

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[Procedure amendment]

[Submission date] October 13, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 1

[Correction method] Change

[Correction content]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Change

[Correction content]

In general, the laser beam entrance / exit end face 1b of the slab 1 is Brewster cut or coated with an antireflection film, so that
It is configured to have low reflection and low loss. However, it is impossible to set the reflectance to 0, and the reflected lights 51 and 52 (stray light) from the laser medium end surface of the laser main beam 5 cannot be completely suppressed. In addition to the light 51 reflected to the external space, there are two types of light reflected on the end surface, that is, the light 52 reflected inside the slab 1 and then refracted at the slab 1 facing plane 1a and emitted to the external space.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0005

[Correction method] Change

[Correction content]

[0005]

Since the conventional solid-state laser device is configured as described above, the reflected light 51, 52 (stray light) from the laser beam entrance / exit end face 1b of the slab 1 is stray light.
Cannot be completely suppressed , and these reflected lights 51, 5
2 is irradiated to the laser housing 8 and the lamp terminal holder 9 attached to the laser housing 8 and the like, and there is a problem that these are damaged. Even before the damage, outgas is generated from the irradiated areas of the reflected light 51, 52, and these fumes are not only good in the optical path of the laser main beam, but also reduce the beam quality and laser output, or near the slab end. There is a problem that fume adheres to and is polluted, and the slab is distorted due to the heating of the polluted portion, and the beam quality and the laser output are reduced.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0020

[Correction method] Change

[Correction content]

Therefore, in this embodiment, a light shielding member 10 having durability against a laser beam is provided on the surface of the support 9 of the lamp terminal to shield the end face reflected lights 51 and 52 from each other.
Is prevented from irradiating. As the light shielding member 10, alumina ceramics, silica ceramics, or the like, which has durability against a laser beam and does not generate outgas, is suitable. If a material that absorbs a laser beam, such as aluminum that has been subjected to black alumite treatment, is used as the light shielding member 10, the end face reflected lights 51 and 52 on the surface of the light shielding member 10 are used.
This is more effective because it can reduce the re-reflection of the laser beam and the irradiation and heating of the laser beam in the peripheral portion.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Name of item to be corrected] 0022

[Correction method] Change

[Correction content]

Example 3. In the third embodiment shown in FIG.
A flow path 10b of cooling water is provided inside the light shielding member 10 to perform water cooling to prevent heating due to absorption of light reflected by the end surface of the light shielding member 10. Especially when performing vibration high output onset of several 100 w,
The temperature rise due to the absorption of the laser beam of the light blocking member 10 is also high, and this heat may heat and distort the end portion of the slab 1 via the structure such as the housing 8 and the atmosphere, thereby performing a more stable laser operation. Therefore, it is effective to cool the light shielding member 10 with water.

Claims (5)

[Claims] 1. A slab type laser medium comprising a pair of opposed side surfaces and a pair of end faces through which a laser beam enters and exits, excitation means for optically exciting the laser medium, and cooling of the laser medium from at least one of the pair of flat surfaces. In the solid-state laser device having a cooling means, a light-shielding mechanism that blocks stray light of the laser beam generated near the end face of the laser medium is provided. 2. The solid-state laser device according to claim 1, wherein the light-shielding mechanism is made of a light-shielding material having durability against the laser beam and absorbing the laser beam. 3. A solid-state laser device, wherein the light-shielding mechanism according to claim 1 is made of a light-shielding material that is durable against a laser beam and reflects the laser beam. 4. The solid-state laser device according to claim 1, further comprising a light-shielding member cooling means. 5. A solid-state laser comprising a light-shielding mechanism according to claim 1 and a mechanism for generating a gas flow between an end of a laser medium and an optical path of a laser beam. apparatus.