JPH06164022A - Laser oscillation apparatus - Google Patents

Abstract

PURPOSE:To enhance the starting property of a laser oscillation apparatus, to make the output of the apparatus large by enhancing its oscillation efficiency and to make the apparatus small-sized as a whole. CONSTITUTION:Excitation lamps 2 by which a laser-beam generating rod 1 is irradiated with excitation light are arranged and installed in a state parallel to the optical-axis line B of the laser-beam generating rod, and electrodes 5 for the excitation lamps 2 are constituted so as to be bent at right angles to, or at an acute angle to, the direction of the optical-axis line B.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser oscillating device, and more particularly to a technique for improving oscillation efficiency by narrowing a distance between rods and the like on an optical axis.

[0002]

2. Description of the Related Art In a rod-type solid-state laser such as Nd / YAG, a plurality of laser light generating rods (hereinafter, The rods (abbreviated as rods) are arranged in a cascade on the same optical axis.

Further, as shown in FIG. 4, an appropriate number of excitation lamps 2 such as arc lamps for generating excitation light are arranged on the side of the rod (laser light generating rod) 1, and the excitation lamps 2 A reflector cylinder 3 for reflecting the excitation light and irradiating the rod 1 in a concentrated manner is arranged around the. Then, laser light is generated by applying excitation light to each of the plurality of rods 1, and the rods are reciprocated between the rear mirror and the output mirror that face each other at the above-mentioned separated positions,
It is an oscillation state. In FIG. 4, reference numeral 4 is a rod holder, 5 is an electrode, and 6 is a lamp holder.

On the other hand, in the laser oscillating device, the rod 1 is heated by the excitation energy and its temperature rises, so that the optically convex lens is generated based on the difference in thermal expansion and the change in the refractive index due to internal stress. A phenomenon called a thermal lens effect having the property of is likely to occur. Therefore, the parallel state between the path of the laser beam between the rods 1 and the optical axis is broken, and the volume and laser volume that contribute to oscillation inside the rod 1 tend to decrease, and the oscillation efficiency tends to decrease. .

Conventionally, in order to prevent the deterioration of the oscillation efficiency, both ends of the rod 1 have a curvature in consideration of the thermal lens effect, for example, in the case of the rod 1 having a length of 152 mm and a diameter of about 8 mm. A concave surface is preliminarily processed so that the radius becomes -2 m to -1 m to improve the oscillation efficiency.

[0006]

However, in the conventional laser oscillation device shown in FIG. 4, the temperature of the rod 1 does not rise to a temperature at which the thermal lens effect occurs at the initial stage of startup. The concave lens effect on the end face of the rod 1 functions, the generated laser light is likely to be dispersed to the outside, and a large excitation energy is required to reach the oscillating state, so that the threshold value becomes high and the startability is impaired. Become. In order to improve the starting property and improve the above-mentioned oscillation efficiency, it is effective to make the rod-rod distance smaller than the rod-mirror distance, but for that purpose,
It is necessary to reduce the length of the rod holder 4 and the lamp holder 6 protruding outward. Of these, the rod holder 4 may be shortened, but it is technically difficult to shorten the lamp holder 6 due to the length of the electrode 5.

The present invention has been made in view of these circumstances, and improves the startability by decreasing the threshold value of the amount of excitation energy supplied until the start of oscillation, improves the oscillation efficiency, and increases the output. The purpose is to make it easier and to downsize the entire device.

[0008]

[Means for Solving the Problems] Various means for solving these problems are proposed. The laser oscillator according to claim 1 is in a state parallel to the optical axis of the laser light generating rod,
An excitation lamp for irradiating excitation light is arranged on the laser light generating rod, and the electrode of the excitation lamp is bent at a right angle or an acute angle with respect to the optical axis direction. The laser oscillator according to a second aspect is configured such that the laser light generating rod and the excitation lamp are housed in a common casing, which is added to the oscillator of the first aspect. According to a third aspect of the laser oscillation device, a configuration in which a plurality of laser light generating rods are arranged in a cascade arrangement on the same optical axis is added to the oscillation device of the first or second aspect. There is. The laser oscillation device according to claim 4 has a configuration in which an excitation lamp for irradiating excitation light to a laser light generation rod adjacent to the optical axis is arranged at different angles in the circumferential direction of the optical axis. 1,
The oscillation device according to claim 2 or 3 is added.

[0009]

In the laser oscillating device according to the first aspect of the present invention, the electrodes of the excitation lamp are bent and removed from the arrangement direction, so that the interference with the adjacent excitation lamp is reduced and the distance between the rear mirror and the output mirror is correspondingly reduced. And the startability is improved by reducing the laser oscillation distance. In the laser oscillator according to the second aspect, in addition to the operation according to the first aspect, the laser light generating rod and the excitation lamp are housed inside the casing, whereby the overall size of the apparatus is reduced. In the laser oscillator according to claim 3, in addition to the operation according to claim 1 or claim 2, adjacent laser light generating rods are arranged on the same optical axis line, the rod interval is set small, and The influence of diffusion and thermal lens effect is reduced, the coupling loss between rods is reduced,
At the same time, a large output can be achieved. In the laser oscillation device according to claim 4, in addition to the operation according to claim 1, claim 2 or claim 3, when the electrodes of the adjacent excitation lamps are arranged to be displaced in the circumferential direction about the optical axis, The parts projecting outward do not interfere with each other, and the dimension reduction property in the optical axis direction occurs, and since a plurality of excitation lamps are arranged in the circumferential direction, the light amount in the circumferential direction is averaged.
The beam quality of the output laser light can also be improved.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the laser oscillator according to the present invention will be described below with reference to FIGS.

In the embodiment, on the same optical axis B, a plurality of rods 1 are arranged between the rear mirror and the output mirror facing each other at a separated position in a cascade arrangement state. The following technologies are added.

In the excitation lamp 2, as shown in FIG. 1, the end of the quartz glass tube 2a for sealing the discharge gas is bent 90 degrees in the direction away from the rod 1. The electrode 5 is arranged in the bent portion in a state where the tip of the electrode 5 is projected to the center position. For this reason, the optical axis B of the rod 1 and the center line of the excitation lamp 2 are parallel to each other, and as shown in FIG. 2, for example, the pair of electrodes 5 are arranged with their directions turned by 180 degrees.

As shown in FIGS. 1 and 2, a casing having an oblong cross section for forming an oscillation cavity around one rod 1 and two excitation lamps 2 by surrounding them. 7 is adopted and the casing 7
The lamp holder 6 is arranged in the major axis direction.

The casing 7 is formed of a metal material such as stainless steel or a ceramic material, and its inner surface is coated with gold or the like for increasing the reflectance of light rays, or a thin plate having high reflectance is integrally formed. By attaching or the like, the reflecting surface 3 having the function of the above-described reflecting cylinder is integrally formed.

As shown in FIG. 1, the length of the rod holder 4 is shortened so that the end face of the rod holder 4 substantially coincides with the outer portion of the lamp holder 6, and the amount of protrusion in the longitudinal direction is reduced. It

When assembling the laser oscillator, as shown in FIG. 1, the electrode 5 protruding outward from the casing 7 of the same type and the lamp holder 6 accommodating the electrode 5 are aligned. Even in the state in which the rod 1 and the rod holder 4 are in the close state, they can be arranged in a cascade on the same optical axis B.

With such a structure, adjacent portions of the electrode 5 and the lamp holder 6 do not interfere with each other in the longitudinal direction. Therefore, the shortened length of the rod holder 4 reduces the distance between the rods 1. It will be directly linked.

When the distance between the rods 1 becomes small, the temperature of the rods 1 is relatively low as in the initial stage of activation, and when the influence of the concave lens effect on the end face is larger than that of the thermal lens effect,
The amount of laser light that deviates from the end faces of the adjacent rods 1 decreases, and the oscillation start threshold value of excitation light energy decreases. Then, since the dispersion of the laser light is suppressed, the oscillation efficiency is improved.

When the effect of the thermal lens effect is larger than the effect of the concave lens effect on the end face, such as during steady operation, the laser light is likely to be narrowed and the laser volume tends to be small. As the distance becomes smaller, the influence of the decrease in the laser volume is reduced, the oscillation efficiency is improved, and a high output can be obtained.

Further, when the suppression of the dispersion of the laser light when the concave lens effect is affected and the suppression of the reduction of the laser volume when the thermal lens effect is affected, the linearity of the input / output characteristics (that is, the input Correspondence when the excitation light energy amount and the laser light output increase / decrease due to a proportional relationship, etc.)
Is improved, and it becomes easy to adjust the output amount of laser light.

FIG. 3 shows another embodiment of the laser oscillator according to the present invention. In the other embodiment, the electrodes 5 are bent and housed in the quartz glass tube 2a so as to face each other. Even in this example, FIG. 1 and FIG.
In the same manner as in the embodiment shown in (1), the threshold value can be lowered by reducing the distance between the rods 1, the oscillation efficiency can be improved, the laser light output can be improved, and the linearity of the input / output characteristics can be improved.

<Other Embodiments> In the present invention, the following technique can be adopted instead of the above-described embodiment. a) Set the number of excitation lamps 2 around the rod 1 arbitrarily. b) Arranging the electrode 5 and the lamp holder 6 in the adjacent excitation lamp 2 at an arbitrary angle in the circumferential direction. c) To improve the quality of laser excitation light by arranging the position of the excitation lamp 2 around the rod 1 while changing the angle. d) The rod 1 is a solid-state laser such as Nd or YLF.

[0023]

According to the laser oscillating device of the first aspect, the excitation lamp for irradiating the laser light generating rod with the excitation light is arranged in parallel with the optical axis of the laser light generating rod. The electrode has a configuration in which the electrode is bent at a right angle or an acute angle with respect to the optical axis direction, so that the following excellent effects can be obtained. (1) By reducing the amount of protrusion of the electrode in the optical axis direction,
The rod-rod distance is reduced, and the startability during laser oscillation can be improved. (2) When a plurality of laser light generating rods are arranged in a cascade arrangement, interference with the position of the excitation lamp around the rods is less likely to occur, and the arrangement of the casings can be freely arranged by shifting the lamp holder in the circumferential direction. Can be increased. (3) From the above, it is possible to suppress the reduction of the laser volume due to the thermal lens effect, obtain a high oscillation efficiency, and increase the laser light output. (4) The linearity of the input / output characteristics is improved by suppressing the dispersion of the laser light when the concave lens effect due to the concave surface of the rod end is influencing and by suppressing the reduction of the laser volume when the thermal lens effect is influencing. It is improved and the output adjustment of the laser light can be facilitated. According to the laser oscillating device of the second aspect, since the laser light generating rod and the excitation lamp are housed inside a common casing, in addition to the effect of the first aspect, the entire device is provided. There is an effect that the size can be reduced. According to the laser oscillating device of claim 3, a plurality of laser light generating rods are arranged in a cascade arrangement on the same optical axis. Therefore, the effect according to claim 1 or 2 is obtained. In addition to,
The following excellent effects are obtained. (1) The distance between adjacent laser beam generating rods is set to be small, and the influence of the laser beam dispersion and the thermal lens effect is reduced, and a stable laser beam can be obtained. (2) The coupling loss between the rods is reduced, and a plurality of laser light generating rods can increase the output. The laser oscillation device according to claim 4 employs a configuration in which electrodes of an excitation lamp for irradiating excitation light to a laser light generating rod adjacent to the optical axis are arranged at different angles in the circumferential direction of the optical axis. Therefore, in addition to the effects according to claim 1, claim 2 or claim 3, the following excellent effects can be obtained. (1) The electrodes of adjacent excitation lamps are displaced in the circumferential direction,
The electrodes and the like of the excitation lamp protruding outward do not interfere with each other, and the entire device can be shortened. (2) By arranging a plurality of excitation lamps in the circumferential direction, it is possible to average the amount of light in the circumferential direction and improve the beam quality.

[Brief description of drawings]

FIG. 1 is a front sectional view of an essential part showing an embodiment of a laser oscillator according to the present invention.

FIG. 2 is a side view of a main part showing an embodiment of a laser oscillation device according to the present invention.

FIG. 3 is a front sectional view showing another embodiment of the laser oscillator according to the present invention with a part of the main part omitted.

FIG. 4 is a front sectional view showing a conventional example of a portion of a rod holder and a lamp holder in a laser oscillator.

[Explanation of symbols]

 1 Laser Light Generation Rod (Excitation Lamp) 2 Excitation Lamp 2a Quartz Glass Tube 3 Reflecting Cylinder (Reflecting Surface) 4 Rod Holder 5 Electrode 6 Lamp Holder 7 Casing B Optical Axis

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Fumio Matsuzaka Fumio Matsuzaka 3-15-15, Hoshu, Koto-ku, Tokyo Ishikawajima Harima Heavy Industries Co., Ltd. Toni Technical Center

Claims (4)

[Claims] 1. An excitation lamp for irradiating the laser light generation rod with excitation light is arranged in parallel with the optical axis of the laser light generation rod, and the electrode of the excitation lamp is perpendicular to the optical axis direction. Alternatively, the laser oscillator is characterized by being bent at an acute angle. 2. The laser oscillation device according to claim 1, wherein the laser light generating rod and the excitation lamp are housed in a common casing. 3. The laser oscillating device according to claim 1, wherein a plurality of laser light generating rods are arranged in a cascade arrangement on the same optical axis. 4. An excitation lamp for irradiating excitation light to a laser light generating rod adjacent to the optical axis is arranged at different angles in the circumferential direction of the optical axis.
The laser oscillation device according to 2 or 3.