JP3086090B2 - Gas laser equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser beam having excellent symmetry, which is a rectangular laser beam emitted from a resonator.
The present invention relates to a gas laser device for shaping into a shape.

[0002]

2. Description of the Related Art FIG.
No. 8 “Corrective Optics for Rectangle Laser Beams”
TICS FOR RECTANGULAR LARSE
FIG. 2 is a perspective view showing a conventional gas laser device described in (R BEAMS). In the figure, 1 is a gain medium having a rectangular cross section, 2 is an aperture, and 3 is a laser beam emitted from the gain medium 1. 4 is a plane mirror,
5 and 6 are spherical mirrors, and 7 is a plane mirror. Then, the laser beam 3 emitted from the aperture 2 is reflected by the plane mirror 4 and guided to the spherical mirror 5 at a predetermined angle. The laser light 3 guided to the spherical mirror 5 is reflected at a predetermined angle and is converted into a laser beam 3A. The converted laser beam 3A becomes a laser beam 3B via the spherical mirror 6 and the plane mirror 7, and is emitted.

Here, the characteristics of the spherical mirrors 5 and 6 will be described. When a laser beam is incident on the spherical mirror 5 or 6 at a predetermined angle, the spherical mirrors 5 and 6 operate as mirrors having different radii of curvature in the vertical and horizontal directions. This is due to astigmatism , and as a result, the vertical and horizontal focal lengths of the spherical mirrors 5 and 6 change. Therefore, the focal length of the laser beam can be arbitrarily changed by changing the incident angle of the laser beam and the radius of curvature of the spherical mirror. By utilizing this phenomenon, the outer diameter of the laser beam in both directions can be adjusted by the spherical mirror 5 and the divergence angle of the laser beam in both directions can be controlled by the spherical mirror 6. Thus, a rectangular laser beam can be converted into a laser beam having excellent symmetry .

Next, the operation will be described. First, a rectangular laser beam 3 is extracted from a rectangular gain medium 1 having excellent heat radiation characteristics, and the extracted rectangular laser beam is incident on a spherical mirror 5 via a plane mirror 4 at a predetermined angle.
In this case, the laser beam 3A reflected by the spherical mirror 5 is not
Astigmatism occurs and propagates on the gain medium to different focal points in the vertical and horizontal directions of the spherical mirror 5. Thus, the laser beam 3A reflected by the spherical mirror 5 is guided to the spherical mirror 6 via the first focus line 8 and the second focus line 9. The spherical mirror 6 is located at a position where the vertical length and the horizontal length of the laser beam 3A are equal, and
The laser beams 3A guided to the spherical mirror 6 have the same vertical and horizontal lengths because they are arranged at a predetermined angle so as to cause astigmatism. The divergence angle between the vertical direction and the horizontal direction is adjusted.

As described above, the laser beam reflected from the spherical mirror 6 in the state where the vertical length and the horizontal length are equal and the divergence angles in both directions are adjusted, is transmitted through the plane mirror 7 in the vertical and horizontal directions. Laser beam 3B having the same length and the same divergence angle in both directions. Therefore,
When this laser beam 3B is condensed by a lens or the like and used for processing or the like, high-quality processing without anisotropy in both the vertical and horizontal directions can be realized.

[0006]

Since the conventional gas laser device is constructed as described above, a plurality of spherical mirrors 5 are provided.
If the installation position of 6, or the incident angle is shifted, an isotropic laser beam cannot be obtained, and if the spherical mirrors 5, 6 and the plane mirrors 4, 7 are deteriorated, a high-output laser beam cannot be obtained. And the reliability of the gas laser device is low.

The first to fifth aspects of the present invention have been made to solve the above-described problems, and provide a highly reliable gas laser apparatus by reducing the number of optical systems for shaping a laser beam. The purpose is to do.

[0008]

A gas laser device according to a first aspect of the present invention has a rectangular cross section from an oscillator, and
The laser beam of the lowest single transverse mode is extracted in both the short side and long side directions, and the divergence angle of the laser beam is adjusted in two directions to a position where the extracted laser beam propagates naturally and the beam diameter in two directions becomes equal. The optical element is provided.

Further, the gas laser device according to claim 2 is
An optical element having a different focal length in two orthogonal directions is provided at a position where the beam diameter of the emitted laser beam is equal in two orthogonal directions.

Further, in the gas laser device according to a third aspect, a transmission type optical element having a different focal length in the two orthogonal directions is disposed at a position where the beam diameter of the emitted laser beam is equal in the two orthogonal directions. It was done.

In the gas laser apparatus according to a fourth aspect, a reflection type optical element having a different focal length in the two orthogonal directions is provided at a position where the beam diameter of the emitted laser beam is equal in the two orthogonal directions. It was done.

A gas laser device according to claim 5 is
The spherical mirror is disposed at a position where the beam diameter of the emitted laser beam is equal in two orthogonal directions and inclined at a predetermined angle.

[0013]

The gas laser device according to the first aspect of the invention emits rectangular laser beams having different divergence angles in two orthogonal directions. This rectangular laser beam has a short side length of 2
Since it is as small as about mm, the divergence angle of the laser beam in the short side direction is very large, and since the length of the long side is as large as 5 mm or more, the divergence angle of the laser beam in the long side direction is small. Therefore, if the rectangular laser beam propagates a predetermined short distance, the beam diameters in the two directions become equal. The optical element is arranged at a position where the beam diameter becomes equal in two directions, and the divergence angle of the laser beam in two orthogonal directions is adjusted, so that the cross section becomes
Obtain a beam with excellent symmetry .

In the gas laser apparatus according to the second aspect of the present invention, optical elements having different focal lengths in two orthogonal directions are arranged at positions where the beam diameter of the emitted laser beam is equal in the two orthogonal directions. Therefore, the divergence angle of the laser beam can be adjusted in two orthogonal directions.
Obtains a beam with excellent symmetry in cross section.

Further, in the gas laser apparatus according to the third aspect of the present invention, a transmission type optical element having a different focal length in two orthogonal directions is disposed at a position where the beam diameter of the emitted laser beam is equal in the two orthogonal directions. The divergence angle of the laser beam is adjusted in two orthogonal directions so that the cross section is symmetric.
To get an excellent beam .

In the gas laser apparatus according to the fourth aspect of the present invention, a reflective optical element having a different focal length in two orthogonal directions is disposed at a position where the beam diameter of the emitted laser beam is equal in the two orthogonal directions. The divergence angle of the laser beam is adjusted in two orthogonal directions so that the cross section is symmetric.
To get an excellent beam .

In the gas laser apparatus according to the fifth aspect of the present invention, the spherical mirror is disposed at a position where the beam diameter of the emitted laser beam is equal in two directions orthogonal to each other with a predetermined angle of inclination. By adjusting the angles in two directions perpendicular to each other, a beam having a cross section excellent in symmetry can be obtained.

[0018]

【Example】

Embodiment 1 FIG. An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, reference numerals 10 and 11 denote metal electrodes.
2 is an RF power supply connected to the electrode 10, 13 and 14 are dielectric plates made of, for example, ceramics, which are in close contact with the metal electrodes 10 and 11, and 15 is a discharge space formed between the dielectric plates 13 and 14. , 16 and 17 indicate arrows for entering and exiting the electrode cooling water, 18 and 19 indicate optical resonator mirrors (resonators), 20 indicates a laser beam, and 21 indicates a cylindrical lens (optical element) for adjusting the divergence angle of the laser beam. Element).

Here, the resonator of the gas laser device of the present invention will be described. In the resonator, as shown in FIG. 1, the width W of the discharge space 15 is set to 100 mm, the gap length D is set to 2 mm, and a waveguide resonator is assembled in the gap length D direction (shorter diameter direction). Is configured to be selected.
In addition, in the width direction W (the major axis direction), an enlargement ratio M =
The single-sided unstable resonator of 1.3 is assembled so as to select the lowest-order transverse mode. According to the resonator configured as described above, the diameter of the laser beam emitted from the one-sided unstable resonator is 23.1 mm, and the diameter of the laser beam emitted from the waveguide resonator is 2 mm. Therefore, the laser beam 20 output from the take-out mirror 19 is formed in a rectangular cross section with each side having a length of 23.1 mm and 2 mm. Since the beam diameter emitted from the waveguide resonator is as small as 2 mm, the divergence angle of the laser beam 20 in that direction is large. As a result, the laser beam 20 naturally propagates only about 2 m from the resonator mirror 19, and the beam diameter emitted from the waveguide resonator and the beam diameter emitted from the unstable type resonator become almost as shown in FIG. Become equal. In FIG. 3, the vertical axis represents the output energy intensity, and the horizontal axis represents the distance in the beam radial direction.
The solid line indicates the laser beam emitted from the waveguide resonator, and the dotted line indicates the laser beam emitted from the unstable resonator. Although this example shows the case of the negative branch type, the same applies to the case of the positive branch type.

Next, the operation will be described. One electrode 1
When 0 is connected to the RF power supply 12 and the other electrode 11 is connected to the ground, an RF discharge for exciting the laser is generated in the discharge space 15. The discharge energy is converted into light energy by an optical resonator constituted by the total reflection mirror 18 and the take-out mirror 19, and output as a rectangular laser beam 20 from the take-out mirror 19. In this case, as described above, the rectangular laser beam 20 output from the take-out mirror 19 becomes a laser beam 20 having an excellent symmetrical cross section when propagated spontaneously by about 2 m. The cylindrical lens 21 is disposed at this position where the cross section of the naturally propagated laser beam 20 becomes square. The cylindrical lens 21 is designed to have a focal length of 2 m in a direction corresponding to the waveguide resonator and a focal length に は in a direction corresponding to the unstable resonator. Thus, when the laser beam 20 passes through the cylindrical lens 21, the laser beam emitted from the unstable resonator and the laser beam emitted from the waveguide resonator become parallel to each other. Therefore, the laser beam 22 transmitted through the cylindrical lens 21 is shaped into a parallel laser beam having a square cross section. FIG. 4 shows how the beam is shaped at this time. It can be seen that laser beams having different beam diameters and divergence angles in two orthogonal directions can be corrected by one optical element (cylindrical lens 21). FIG. 5 shows an intensity distribution when the laser beam 22 corrected by this system is propagated for 100 m. It can be confirmed that the intensity distributions of the laser beams in both directions almost overlap each other, and that the distribution is good in a Gaussian shape. In FIG. 5, the vertical axis is the output energy intensity, and the horizontal axis is the horizontal axis.
The axis indicates the distance in the beam radial direction , the solid line indicates the laser beam emitted from the waveguide resonator, and the dotted line indicates the laser beam emitted from the unstable resonator.

Embodiment 2 FIG. In the first embodiment, the case where the transmission type optical element (the cylindrical lens 21) is used has been described. However, the present invention is not limited to this, and the same effect can be obtained by using the reflection type optical element.

Embodiment 3 FIG. Further, in the first embodiment, the example in which the cylindrical lens 21 is used as the optical element has been described. However, similar effects can be obtained by using the spherical mirror 23 in an inclined manner as in the third embodiment shown in FIG. That is, as shown in FIG. 7, when the laser beam emitted from the take-out mirror 19 is incident on the spherical mirror 23 having a radius of curvature R at an incident angle θ, the equivalent focal lengths in two orthogonal directions are f1 = Rcos θ / 2 f2 = R / ( 2 cos θ) . Here, f1 indicates the focal length in the direction perpendicular to the paper surface in FIG. 7, and f2 indicates the focal length in the direction parallel to the paper surface in FIG. Accordingly, f1 is the focal length of the laser beam emitted from the waveguide resonator, and f2 is the focal length of the laser beam emitted from the unstable resonator. Thus, if the incident angle θ of the laser beam 20 incident on the spherical mirror 23 having the radius of curvature R is appropriately selected, the same effect as that of the cylindrical lens 21 can be obtained. still,
In FIG. 6, a dotted line indicates a laser beam emitted from the unstable resonator, and a solid line indicates a laser beam emitted from the waveguide resonator.

[0023]

As described above, according to the first aspect, a rectangular laser beam is emitted in which the divergence angle of the laser beam in the short side direction is very large and the divergence angle of the laser beam in the long side direction is small. Further, an optical element is disposed at a position where the beam diameters in the two directions are equal to each other so that the divergence angle of the laser beam is orthogonal.
The cross section is excellent in symmetry because it is configured to adjust in the direction.
Beam can be obtained. As described above, a rectangular laser beam is converted into a symmetrical laser beam by a single optical element, thereby preventing positional deviation and angular deviation of the optical element, and further reducing the influence of deterioration of the optical element. Therefore, a highly reliable, low-cost and easy-to-use gas laser device can be obtained.

According to the second aspect of the present invention, the optical elements having different focal lengths in the two orthogonal directions are provided at positions where the beam diameter of the emitted laser beam is equal in the two orthogonal directions. By adjusting the divergence angle of the laser beam in two directions orthogonal to each other, it is possible to obtain a beam whose cross section is excellent in symmetry .

According to a third aspect of the present invention, a transmission type optical element having a different focal length in the two orthogonal directions is provided at a position where the beam diameter of the emitted laser beam is equal in the two orthogonal directions. With this configuration, the divergence angle is adjusted in two orthogonal directions while the laser beam goes straight,
A beam having excellent symmetry can be obtained.

According to a fourth aspect of the present invention, a reflective optical element having a different focal length in the two orthogonal directions is provided at a position where the beam diameter of the emitted laser beam is equal in the two orthogonal directions. The divergence angle of the laser beam is adjusted in two orthogonal directions in a state where the optical element is less susceptible to deterioration of the optical element compared to the transmission type optical element, so that a beam with an excellent symmetrical cross section can be obtained. Can be.

According to the fifth aspect, the spherical mirror is disposed at a position where the beam diameter of the emitted laser beam is equal to the two orthogonal directions at a predetermined angle, so that the two directions are orthogonal to each other. Without using optical elements having different focal lengths, the divergence angle of the laser beam can be easily adjusted in two orthogonal directions to obtain a beam having an excellent symmetrical cross section.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing a resonator configuration according to the first embodiment of the present invention.

FIG. 3 is a graph showing an intensity distribution of a laser beam when 2 m free propagation is performed in the resonator configuration of FIG. 2;

FIG. 4 is a diagram showing operating characteristics of the first embodiment of the present invention.

FIG. 5 is a graph showing an intensity distribution after a laser beam is shaped by the cylindrical lens according to the first embodiment of the present invention.

FIG. 6 is a diagram showing a third embodiment of the present invention.

FIG. 7 is a diagram illustrating a reflection state of a laser beam according to a third embodiment.

FIG. 8 is a perspective view showing a conventional gas laser device.

[Explanation of symbols]

 18 Total reflection mirror (resonator) 19 Extraction mirror (resonator) 20, 22 Laser beam 21 Cylindrical lens (optical element) 23 Spherical mirror (optical element)

Continuing from the front page (72) Inventor Kenji Yoshizawa 8-1-1, Tsukaguchi-Honcho, Amagasaki-shi The Central Research Laboratory of Mitsubishi Electric Corporation (72) Inventor Masato Matsubara 8-1-1, Tsukaguchi-Honcho, Amagasaki-shi Mitsubishi Electric Corporation (56) References JP-A-4-263131 (JP, A) JP-A-60-22392 (JP, A) JP-A-1-109317 (JP, A) JP-A-61-283187 (JP, A) U.S. Pat. No. 4,921,338 (US, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01S 3/101 G02B 27/09 H01S 5/00 -5/50

Claims (5)

(57) [Claims] 1. A different resonator is formed in two orthogonal directions, a lowest-order fundamental transverse mode having different laser beam diameters is selected in two directions, and rectangular laser beams having different divergence angles are emitted in the respective directions. An optical element for adjusting the divergence angle of the laser beam in two directions orthogonal to each other at a position where the emitted rectangular laser beam is freely propagated and the beam diameters in the two directions are equal. Characteristic gas laser device. 2. A different resonator is formed in two orthogonal directions, a lowest-order fundamental transverse mode having different laser beam diameters in two directions is selected, and rectangular laser beams having different divergence angles are emitted in the respective directions. in the gas laser apparatus, with the emitted rectangle-shaped laser beam is freely propagated beam diameter in two directions equal position, by arranging the different optical elements in the two directions focal length orthogonal, the two directions Laser
A gas laser device wherein the divergence angles of beams are adjusted to be equal . 3. The gas laser device according to claim 2, wherein the optical element is a transmission type optical element. 4. The gas laser device according to claim 2, wherein the optical element is a reflection type optical element. 5. A different resonator is formed in two orthogonal directions, a lowest-order fundamental transverse mode having different laser beam diameters in two directions is selected, and rectangular laser beams having different divergence angles are emitted in the respective directions. In the gas laser device, a spherical mirror is disposed at a position where the emitted rectangular laser beam is freely propagated and the beam diameters in the two directions are equal to each other at a predetermined angle , and the divergence angle of the laser beam in the two directions is reduced. equally
A gas laser device, which is adjusted so as to be as follows.