JP2002237636A - Solid-state laser - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid-state laser which can superimpose two laser beams, resulting from a continuous oscillation and a pulse oscillation and is capable of laser-oscillation at a high efficiency, with the laser beam quality kept at a high level, capable of changing the output ratio of the continuous oscillation to the pulse oscillation. SOLUTION: The laser comprises a lengthwise left part of a YAG rod 41, a pulse lamp 21 which faces the left part of the rod 41 and pulse-lights, a pulse exciter 12 having a reflective drum 22 enclosing the pulse lamp 21 and the left part of the rod 41, a CW lamp 23 which faces a lengthwise right part of the rod 41 and is continuously light, and a continuous excitation unit 13, having a reflective drum 24 enclosing the CW lamp 23 and the right part of the rod 41.

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 in which excitation light from an excitation light source is reflected by a reflecting tube and condensed on a solid-state laser medium, and laser light is oscillated from the solid-state laser medium.

[0002]

2. Description of the Related Art There are two types of laser light: continuous oscillation (CW oscillation) and pulse oscillation. In continuous oscillation in which the excitation lamp is continuously turned on, the laser light is also emitted continuously, while in pulse oscillation in which the excitation lamp is turned on intermittently, the laser light is also emitted intermittently. This difference in oscillation method is manifested in, for example, laser welding characteristics. In continuous oscillation, the penetration is shallow, but the weld surface bead is smooth and clean, while in pulse oscillation, the penetration is deep, but the welding surface is rough and dirty.

If laser light obtained by superposing continuous oscillation and pulse oscillation is used for the purpose of complementing the characteristics of the two oscillation systems, it is possible to cope with welding of various materials having different material characteristics. . For example, when welding a material having a high reflectance to laser light, such as aluminum, pulsed laser light capable of obtaining high peak output laser light is generally used. However, since the thermal conductivity of aluminum is high, the diffusion of absorbed heat is rapid, so that the molten pool is rapidly cooled, and thus there is a problem that cracks occur in the welded portion. Therefore, by superimposing the laser beam of continuous oscillation on the laser beam of pulse oscillation having a high peak, it is possible to prevent the welding portion from being rapidly cooled during the pulse and to avoid welding cracks.
For this reason, various solid-state laser devices capable of superposing two laser beams by continuous oscillation and pulse oscillation have been proposed.

FIGS. 4 and 5 are views showing a conventional solid-state laser device. FIG. 4 is a view showing the entire structure thereof, and FIG. 5 is an enlarged sectional view taken along line BB of FIG. is there. This solid-state laser device includes a rear mirror 31 and an output mirror 3
2, an excitation unit 33, a beam expander 34, an optical fiber incident lens 35, and an optical fiber 36 are provided. The excitation unit 33 includes a YAG rod 41 and YAG rods on both sides of the YAG rod 41.
A continuous oscillation excitation lamp 42 and a pulse oscillation excitation lamp 43 disposed in parallel with the rod 41, and the YAG rod 41, the excitation lamp 42, and the excitation lamp 4
And a reflection tube 44 surrounding the outer periphery of the excitation lamp 3 (in FIG. 4, the excitation lamps are arranged vertically for easy understanding). The reflection cylinder 44 is formed in a tubular shape in which the cross-sectional shape of the inner space is a so-called double ellipse composed of two ellipses partly overlapping with each other.

FIG. 6 is a diagram showing another conventional solid-state laser device. This solid-state laser device has a YAG rod 4
A laser oscillator 52 dedicated to continuous oscillation provided with a continuous excitation section 51 provided with excitation lamps 42, 42 for continuous oscillation on both sides of 1 and excitation lamps 43, 43 for pulse oscillation on both sides of the YAG rod 41. And a laser oscillator 54 dedicated to pulse oscillation provided with a pulse excitation unit 53. The laser light generated by the pulse oscillation from the laser oscillator 54 is collimated by the two mirrors 55 and 56 with the laser light emitted by the continuous oscillation from the laser oscillator 52 in front of the optical fiber incident lens 35, and these two laser lights are combined. After that, the light enters the optical fiber incident lens 35 and is condensed on the incident end of the optical fiber 36 by the optical fiber incident lens 35.

FIG. 7 is a diagram showing still another conventional solid-state laser device. This solid-state laser device is an improvement of the solid-state laser device of FIG. That is, in this solid-state laser device, the laser beam from the laser oscillator 54 dedicated to pulse oscillation is shaped into a ring-shaped laser beam by the cone-shaped beam expander 61, and a perforated total reflection at an incident angle of 45 ° is performed. The light is reflected at right angles by the mirror 62. A laser beam from a laser oscillator 52 dedicated to continuous oscillation is transmitted to a perforated total reflection mirror 62.
Pass through the through-hole 62a at the center portion. In this way,
The laser light generated by the pulse oscillation from the laser oscillator 54 and the laser light generated by the continuous oscillation from the laser oscillator 52 are combined in front of the optical fiber incident lens 35 and then enter the optical fiber incident lens 35. Is condensed at the incident end of the.

[0007]

In the solid-state laser device shown in FIGS. 4 and 5, the excitation light from the two excitation lamps, that is, the excitation lamp 42 for continuous oscillation and the excitation lamp 43 for pulse oscillation, Since the light is reflected by the reflecting surface 44a of the reflecting cylinder 44 and is condensed on one YAG rod 41, two laser beams by continuous oscillation and pulse oscillation can be superposed.

However, the YAG rod 41 is heated in a radial direction of the YAG rod 41 by heating by absorbing the excitation light and cooling by cooling water (not shown).
A temperature distribution occurs in which the center is hot and the outer periphery is cold. This temperature distribution causes the YAG rod 41 to act as a lens (thermal lens) because the refractive index of the YAG rod 41 depends on the temperature. For this reason, even if the superposition of two laser beams by continuous oscillation and pulse oscillation becomes possible, the input power to each of the excitation lamp 42 for continuous oscillation and the excitation lamp 43 for pulse oscillation is always kept the same. Otherwise, the excitation by the respective excitation lamps 42 and 43 of the YAG rod 41 will be non-uniform, and the thermal lens will be distorted, and as a result, the beam quality of the laser light will be degraded. Therefore, this solid-state laser device has a problem that the ratio between the continuous output of laser light and the pulse output cannot be set to other than 1: 1. Further, in this solid-state laser device, since the YAG rod 41 is excited by the excitation lamp 42 for continuous oscillation and the excitation lamp 43 for pulse oscillation disposed on both sides thereof, the YAG rod 41 and these excitation lamps 42, The reflecting tube 44 that covers 43 is a reflecting tube having a double elliptical cross section. In the case of this double elliptical reflecting cylinder, a part of one excitation light leaks to the other lamp side, so that there is a problem that the excitation efficiency is deteriorated.

On the other hand, in the solid-state laser device shown in FIG. 6, when the beam quality of the laser light from the laser oscillator 52 and the laser oscillator 54 is the same, the condensing diameter at the incident end of the optical fiber 36 becomes smaller.
The light collection diameter is determined by the light collection angle. On the other hand, the optical fiber 36 has a maximum allowable incident angle, and it is usually necessary to make the laser light incident within that angle.

However, in this solid-state laser device, since the two laser beams from the laser oscillator 52 and the laser oscillator 54 are incident on the optical fiber incident lens 35, each laser beam has an original maximum allowable incident angle of the optical fiber 36. It must be incident on the incident end of the optical fiber 36 at an angle of less than half. Accordingly, the condensing diameter is twice or more as large as that when laser light is incident from each of the single laser oscillators 52 and 54, and the core diameter of the optical fiber is also twice as large. As a result, there is a problem that beam quality is degraded.

In the solid-state laser device shown in FIG. 7, a laser beam from a laser oscillator 52 dedicated to continuous oscillation passes through the inside of a laser beam from a laser oscillator 54 having a ring-shaped cross section and enters an optical fiber. Since the light is incident on the lens 35, it must be incident on the incident end of the optical fiber 36 at an angle smaller than the original maximum allowable incident angle of the optical fiber 36. Therefore, the light collection diameter
The size becomes larger than a case where laser light is incident from the single laser oscillators 51 and 52 alone, so that the core diameter of the optical fiber 36 becomes large, and as a result, the beam quality deteriorates.

The present invention has been made in view of the above circumstances, and in a solid-state laser device capable of superposing two laser beams by continuous oscillation and pulse oscillation, laser oscillation can be performed with high efficiency. An object of the present invention is to provide a solid-state laser device capable of changing the output ratio between continuous oscillation and pulse oscillation while maintaining high beam quality of laser light.

[0013]

In order to achieve the above object, a solid-state laser device according to the present invention comprises a solid-state laser medium having one longitudinal side portion and one side portion of the solid-state laser medium opposed to each other. A pulse excitation unit including a first excitation light source that is pulsed and lit, a first reflection tube surrounding the first excitation light source and one side of the solid-state laser medium, and a longitudinal section of the solid-state laser medium. Direction, a second excitation light source that is arranged opposite to the other side of the solid-state laser medium and is continuously lit, and surrounds the second excitation light source and the other side of the solid-state laser medium. A continuous excitation section provided with a second reflecting cylinder.

In the solid-state laser device according to the present invention, the excitation light from the first excitation light source that is pulse-lit is reflected by the reflection surface of the first reflection tube, and is condensed on one side of the solid-state laser medium. Then, the one side portion is excited, whereby the laser light by pulse oscillation is oscillated from the pulse excitation section. On the other hand, the excitation light from the second excitation light source that is continuously turned on is reflected by the reflection surface of the second reflection tube, and is condensed on the other side of the solid-state laser medium, and excites the other side. As a result, a laser beam due to continuous oscillation is oscillated from the continuous excitation unit. Then, the laser light by the pulse oscillation and the laser light by the continuous oscillation are superposed and oscillated.

According to the solid-state laser device of the present invention, the pulse excitation section includes one longitudinal portion of the solid-state laser medium, the first excitation light source that oscillates the pulse, and the first reflection tube that surrounds these. On the other hand, the continuous excitation section includes the second excitation light source that is continuously lit on the other side in the longitudinal direction of the solid-state laser medium and the second reflection tube that surrounds them, so that the pulse excitation section and the continuous excitation section Are provided independently on one side and the other side in the longitudinal direction of one solid-state laser medium. Here, since the thermal lens generated in the solid-state laser medium is integrated in the longitudinal direction of the solid-state laser medium, one side portion and the other side in the longitudinal direction of the solid-state laser medium as in the solid-state laser device of the present invention. When the independent pulse excitation section and the continuous excitation section are formed in portions, independent thermal lenses can be formed in one side portion and the other side portion of the solid-state laser medium. Thereby, even if the power supplied to the first excitation light source of the pulse excitation unit and the second excitation light source of the continuous excitation unit is changed,
The thermal lens does not become non-uniform, and the beam quality of the laser beam can be maintained at high quality. Therefore, the output ratio between continuous oscillation and pulse oscillation can be changed while maintaining the beam quality of the laser light at high quality.

Further, since one side in the longitudinal direction of the solid-state laser medium is excited by the first excitation light source, and the other side of the solid-state laser medium is excited by the second excitation light source, the first excitation light source of the pulse excitation section is excited. Of the solid-state laser medium and the first excitation light source, and the other side of the solid-state laser medium and the second excitation light source, respectively. Just fine. Therefore, as each of the first reflecting tube and the second reflecting tube,
Since a reflection tube having a single elliptical cross section can be used, a part of one excitation light leaks to the other excitation light source side, as in the case of using a reflection tube having a double ellipse cross section. Because of this, the excitation efficiency is higher than that of a double elliptical reflecting cylinder.

Furthermore, since two laser beams generated by continuous oscillation and pulse oscillation can be superposed in the excitation section, two laser beams generated by continuous oscillation and pulse oscillation are combined in front of the optical fiber incident lens 35, as in the case of combining the two laser beams. The beam diameter does not increase, and as a result, the beam quality does not deteriorate.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. In each drawing, the same components as those in FIGS. 4 to 7 are denoted by the same reference numerals, and description thereof will be simplified. 1 to 3 are views showing a solid-state laser device according to an embodiment of the present invention. FIG. 1 is a view showing the entire configuration, FIG. 2 is an enlarged view of an excitation section in FIG. 1, and FIG. FIG. 3 is a sectional view taken along line AA of FIG. 2. The solid-state laser device according to the present embodiment includes an excitation unit 11 disposed between a rear mirror 31 and an output mirror 32 and a beam expander 3.
4, the optical fiber input lens 35, and the optical fiber 3
6 is provided.

The excitation section 11 includes a pulse excitation section 12 and a continuous excitation section 13. In FIGS. 1 and 2, the pulse excitation unit 12 includes a left portion (one side portion) of a rod-shaped YAG rod (solid laser medium) 41 in the longitudinal direction (direction along the axis) and a left portion of the YAG rod 41. A pulse lamp (first excitation light source) 21 which is arranged in parallel to face each other and which emits a pulse;
And a reflecting tube (first reflecting tube) 22 surrounding the left portion of the YAG rod 41. On the other hand, the continuous excitation section 13 has the YA on the right side (the other side) in the longitudinal direction of the YAG rod 41 and the YA on the opposite side of the YAG rod 41.
A CW lamp (second excitation light source) 23 that is arranged in parallel to the right side of the G rod 41 and is continuously lit, and
The CW lamp 23 and a reflecting tube (second reflecting tube) 24 surrounding the right side portion of the YAG rod 41 are provided.

The reflecting tube 22 and the reflecting tube 24 are respectively
The reflection tube 22 and the reflection tube 2 are formed in a cylindrical shape in which the cross-sectional shape of the space inside is a single ellipse.
Numeral 4 is arranged such that the position of one focal point of the two focal points of each single ellipse in each inner space coincides with each other, and the YAG rod 41 is inserted so as to penetrate these focal point positions. A pulse lamp 21 and a CW lamp 23 are inserted at the positions of the other focal points of the reflection tubes 22 and 24, respectively.

In the solid-state laser device configured as described above, the excitation light from the pulse lamp 21
The light is reflected by the second reflection surface 22a and is condensed on the left portion of the YAG rod 41 to excite the left portion. As a result, laser light generated by pulse oscillation is oscillated from the pulse excitation unit 12. On the other hand, the excitation light from the CW lamp 23 is reflected by the reflection surface 24a of the reflection tube 24, and the YAG rod 41
Is condensed on the right side portion, and the right side portion is excited. As a result, a continuous oscillation (CW oscillation) laser beam is oscillated from the continuous excitation section 13. Then, the laser light by the pulse oscillation and the laser light by the continuous oscillation are superimposed and oscillated from the excitation unit 11.

Since this solid-state laser device includes the pulse excitation section 12 and the continuous excitation section 13, the laser light generated by the pulse oscillation and the laser light generated by the continuous oscillation are superimposed and oscillated from the excitation section 11. be able to. In addition, the pulse excitation section 12 is composed of a left portion of the YAG rod 41 in the longitudinal direction, a pulse lamp 21 and a reflection tube 22 surrounding them, while the continuous excitation section 13
Is composed of the right-hand portion of the YAG rod 41 in the longitudinal direction, the CW lamp 21 and the reflecting tube 24 surrounding them, so that the pulse excitation unit 12 and the continuous excitation unit 13
The YAG rods 41 are independently provided on the left and right portions in the longitudinal direction. The thermal lens generated in the YAG rod 41 is a YAG rod (solid laser medium)
Since this is nothing but the one integrated in the length direction of the YAG rod 41, the pulse excitation unit 12 and the continuous excitation unit independent on the left and right portions in the longitudinal direction (length direction) of the YAG rod 41 as in this solid-state laser device. When the 13 is formed, independent thermal lenses can be formed on the left and right portions of the YAG rod 41. Therefore, the pulse ramp 21 of the pulse excitation unit 12 and the C
Even if the power supplied to the W lamp 23 is changed, the thermal lens does not become non-uniform, and the beam quality of the laser light can be maintained at a high level. Therefore, it is possible to change the output ratio between continuous oscillation and pulse oscillation while maintaining high beam quality of the laser light.

Further, since the left portion of the YAG rod 41 in the longitudinal direction is excited by the pulse lamp 21 and the right portion of the YAG rod 41 is excited by the CW lamp 23, the reflection tube 22 of the pulse excitation unit 12 and the continuous excitation unit are excited. 1
The three reflecting cylinders 24 may surround the left portion in the longitudinal direction of the YAG rod 41 and the pulse lamp 21 and the right portion of the YAG rod 41 and the CW lamp 21 respectively. For this reason, since a reflecting cylinder having a single elliptical cross section can be used for each of the reflecting cylinders 22 and 24, a part of one excitation light is used as in the case of using a reflecting cylinder having a double elliptical cross section. Does not leak to the other lamp side, so that the excitation efficiency is improved as compared with the double elliptical reflecting cylinder.

Further, since two laser beams generated by continuous oscillation and pulse oscillation can be superposed in the excitation unit 11, the laser beam oscillated from the excitation unit 11
The optical fiber 3 is provided by the optical fiber incident lens 35.
6 at the incident end of the optical fiber 36 at the original maximum allowable incidence angle. Therefore, in this solid-state laser device, unlike the case where two laser beams of continuous oscillation and pulse oscillation are combined in front of the optical fiber incident lens 35, the condensing diameter does not become large, and as a result, the beam quality is reduced. , And high quality can be maintained.

[0025]

As described above, according to the present invention,
In a solid-state laser device that can superpose two laser beams by continuous oscillation and pulse oscillation, laser oscillation can be performed with high efficiency, and continuous oscillation and pulse oscillation can be performed while maintaining high beam quality of the laser beam. Can be changed.

[Brief description of the drawings]

FIG. 1 is a diagram showing a solid-state laser device according to an embodiment of the present invention.

FIG. 2 is an enlarged view of an excitation unit in FIG.

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

FIG. 4 is a diagram showing a conventional solid-state laser device.

FIG. 5 is an enlarged sectional view taken along line BB of FIG. 4;

FIG. 6 is a diagram showing another conventional solid-state laser device.

FIG. 7 is a view showing still another conventional solid-state laser device.

[Explanation of symbols]

 Reference Signs List 11 excitation unit 12 pulse excitation unit 13 continuous excitation unit 21 pulse lamp (first excitation light source) 22 reflection tube (first reflection tube) 23 CW lamp (second excitation light source) 24 reflection tube (second reflection tube) ) 31 rear mirror 32 output mirror 34 beam expander 35 optical fiber incident lens 36 optical fiber 41 YAG rod (solid laser medium)

Claims (1)

[Claims] A first excitation light source which is arranged opposite to one side of the solid-state laser medium in a longitudinal direction, and which is disposed to face the one side of the solid-state laser medium and which is pulse-lit;
A pulse excitation unit comprising: a pumping light source and a first reflecting tube surrounding one side of the solid-state laser medium; the other side in the longitudinal direction of the solid-state laser medium; and the other side of the solid-state laser medium A second pumping light source which is disposed opposite to and is continuously lit, and a second pumping light source which surrounds the second pumping light source and the other side of the solid-state laser medium.
A solid-state laser device, comprising: a continuous excitation section having a reflecting cylinder.