JPH088379B2 - CO 2 Lower laser device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a CO ₂ laser device used for processing, medical treatment and the like.

Prior Art FIG. 7 shows a schematic view of a conventional CO ₂ laser device. In this high-speed gas flow type CO ₂ laser device, two pairs of ring-shaped internal electrodes 21 are provided on both end sides and a central portion side of a linear cylindrical discharge tube 22 for exciting and oscillating a CO ₂ laser. By connecting the E-shaped circulation path 23 with three passages, CO
_A laser medium made of a gas containing ₂ is circulated as indicated by an arrow by a roots blower 24 provided in a central passage of a circulation path 23. In addition to the roots blower 24, a vacuum pump 25 for maintaining a constant pressure in the circulation system is provided in the circulation path 23.
And a gas cooler 26 for cooling the heat generated by the discharge,
A gas cooler 27 that cools the compression heat of the roots blower 24 is incorporated.

The laser beam obtained from the high-speed gas flow type CO ₂ laser device configured as described above is provided with a final stage mirror (often a total reflection mirror) 28 provided at one end of the discharge tube 22 and the discharge tube facing it.
The light is amplified between a partial transmission mirror 29 provided at the other end of 22. The transverse mode characteristics showing the intensity distribution of the power of this laser light are the diffraction loss and the Fresnel number N as shown in FIG.
And the Fresnel number N is expressed by the equation N = a ² / d · λ. Here, d is the distance between the final stage mirror 28 and the partial transmission mirror 29, λ is the wavelength of the laser beam, and a is the beam diameter in the discharge tube 22, and this beam diameter is generally the inner diameter of the discharge tube 22. It is proportional and is greatly affected by this inner diameter. In FIG. 9, S is a single mode and M is a multimode. The transverse mode characteristics suitable for cutting of processing are those using the single mode, but in order to obtain more of this single mode, the distance between the final stage mirror 28 and the partial transmission mirror 29 has already been determined. In this case, it is necessary to reduce the inner diameter of the discharge tube 22 to reduce the diffraction loss x of the single mode S and increase the diffraction loss y of the multimode M. At a predetermined point where the Fresnel number N is n in FIG. , Multimode M
The diffraction loss y is larger than the diffraction loss x of the single mode S, and the single mode S having sufficient energy can be obtained.

However, according to this type of CO ₂ laser device, when the inner diameter of the discharge tube 22 is reduced, the discharge tube 22 is discharged from the circulation path 23.
The flow path resistance increases at the connection to the
The differential pressure between the gas pressure P _{1 at} the entrance of the laser medium in 23 and the gas pressure P _{2 at} the exit of the laser medium in the circulation path 23 increases. In the roots blower 24 in which the gas of the laser medium is circulated, the differential pressure and the flow rate capacity for delivering the gas have the characteristics shown in FIG.
When it becomes too large, the flow capacity of the Roots blower 24 is lowered from e to f, and the laser output is lowered.

The present invention solves the above problems, and an object of the present invention is to provide a CO ₂ laser device that can obtain more single modes and does not reduce the laser output.

Means for Solving the Problems In order to solve the above-mentioned problems, the CO ₂ laser device of the present invention is a carbon dioxide gas laser medium in a discharge tube and a circulation path connected to this discharge tube while rapidly circulating the carbon dioxide gas. A CO ₂ laser device that discharges a gas laser medium by discharge excitation in the discharge tube to cause laser oscillation, and extracts laser light from a partially transmissive mirror, wherein at least one of the partially transmissive mirror and a final stage mirror at an end position facing the partially transmissive mirror. The effective diameter was made the same as the effective diameter required for making the laser light into a single mode, and the diameter of the discharge tube was made larger than the effective diameter to reduce the gas flow path resistance between the discharge tube and the circulation path. It is a thing.

Further, another CO ₂ laser apparatus of the present invention discharge-excites the carbon dioxide gas laser medium in the discharge tube while rapidly circulating the carbon dioxide gas laser medium in the discharge tube and a circulation path connected to the discharge tube. Is a CO ₂ laser device that oscillates laser light and takes out laser light from a partial transmission mirror, and between the partial transmission mirror and a final stage mirror facing the partial transmission mirror,
A cutoff member having a hole having the same diameter as the effective diameter required for single mode is provided, and the diameter of the discharge tube is made larger than the effective diameter so that a gas between the discharge tube and the circulation path is formed. The flow path resistance is reduced.

Action With the above configuration, since the effective diameter of at least one of the partial transmission mirror and the final stage mirror is made the same as the effective diameter required for making the laser beam into a single mode, more single modes can be obtained, and the diameter of the discharge tube can be increased. Can be changed. Since the diameter of the discharge tube is increased in this state, the flow path resistance generated at the connection portion between the discharge tube and the circulation path can be suppressed to be small, and a sufficient laser output can be obtained.

Further, in the CO ₂ laser device provided with the cutoff member, since the hole of the cutoff member has the same effective diameter as that required for making the laser beam into single mode, more single modes can be obtained and the discharge tube The diameter can be changed. Since the diameter of the discharge tube is increased in this state, the same operational effect as the CO ₂ laser device can be obtained.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic view of a CO ₂ laser device showing an embodiment of the present invention, and FIGS. 2 and 3 are enlarged views of the main parts of the CO ₂ laser device. In this high-speed gas flow type CO ₂ laser device, the circulation path 3, the roots blower 4, the vacuum pump 5, and the gas coolers 6 and 7 have the same configuration as that of the conventional CO ₂ laser device, and therefore the description thereof will be omitted. The linear cylindrical discharge tube 2 is greatly expanded so that its inner diameter is substantially the same as the inner diameter of the circulation path 3. As shown in FIG. 2, the discharge tube 2 is provided on both end sides and the central side of the discharge tube 2.
The internal electrodes 1 having the same diameter as the above are respectively arranged. Further, a final stage mirror 8 in which a total reflection mirror is often used is arranged at one end of the discharge tube 2, and a partial transmission mirror 9 is arranged at the other end thereof, which face each other. Here, in the partial transmission mirror 9, only the central disk portion 9a serves as a partial transmission mirror, and the peripheral ring-shaped portion 9b only supports the circular disk portion 9a but does not serve as a partial transmission mirror. . And the disc portion 9a
The diameter of is set to such a size that a substantially single mode can be obtained from the relationship with the distance between the final stage mirror 8 and the partial transmission mirror 9. The final stage mirror 8 (not shown) has a similar structure.

With the above configuration, the carbon dioxide gas laser medium is circulated at high speed in the discharge tube 2 and the environment path 3 by the tool blower 4 as shown by the arrow in FIG. The laser light is oscillated by the discharge excitation, and this laser light is taken out from the partial transmission mirror 9. At this time, since the effective diameters of the partial transmission mirror 9 and the final stage mirror 8 are set to be the same as the effective diameter required for making the laser light into single mode, more single modes can be obtained
Further, the diameter of the discharge tube 2 can be changed. In this state, the inner diameter of the discharge tube 2 is greatly expanded so as to be substantially the same as the inner diameter of the circulation path 3. Therefore, the flow path resistance generated at the connection portion between the discharge tube 2 and the circulation path 3 can be suppressed to be small. You can
The difference (pressure) between the pressure P _{1 at} the entrance side of the laser medium and the pressure P ₂ at the exit side of the circulation path 3 becomes almost 0, and the flow capacity of the roots blower 4 is maximized to provide a sufficient laser output. Obtainable.

It should be noted that instead of using both the partial transmission mirror 9 and the final stage mirror 8 that perform their functions only at predetermined locations, the same effect can be obtained by using only one of the mirrors as described above. To be

Instead of providing the ring-shaped internal electrode 1 as shown in FIG. 3, an external electrode 1'opposed to the axial center portion of the discharge tube 2'as shown in FIG. 4 is provided. Provided
It may be applied to a CO ₂ laser device. According to this, when the laser medium has a uniform phase flow, the discharge state in the discharge tube 2 ′ can be made uniform, and the region where the laser light is obtained is the internal electrode. Can be wider than that using.

FIG. 5 is a schematic view of a CO ₂ laser device showing another embodiment of the present invention, and FIG. 6 is an enlarged view of a main part of the CO ₂ laser device. Also in this high-speed gas flow type CO ₂ laser device, the circulation path 13, the roots blower 14, the vacuum pump 15, and the gas coolers 16 and 17 have the same configurations as those of the conventional CO ₂ laser device, and therefore description thereof will be omitted. Then, as in the above-described embodiment, the linear cylindrical discharge tube 12 has an inner diameter that is the circulation path.
The inner diameter of the discharge tube 12 is widened to be substantially the same as the inner diameter of 13, and the inner electrodes 11 having the same diameter as that of the discharge tube 12 are arranged on both end sides and the center side of the discharge tube 12, respectively, as shown in FIG. Has been done. A final stage mirror 18, which is often a total reflection mirror, is provided at one end of the discharge tube 12, and a partial transmission mirror 19 is provided at the other end thereof, which face each other. The final mirror 18 and the partially transmissive mirror 19 merely reflect and partially transmit the entire surface. Further, between the partial transmission mirror 18 and the final stage mirror 19, a hole portion having a size capable of obtaining a single mode is provided.
A cutoff member 20 having 20a is provided, and in the present embodiment, the cutoff member 20 is made of metal, so that it does not adversely affect the discharge state, outside the discharge region, that is, with the partial transmission mirror 18. It is arranged between the inner electrode 11 and its nearest neighbor.

Also with the above configuration, the carbon dioxide laser medium is circulated at high speed in the discharge tube 12 and the circulation path 13 by the tool blower 14 as shown by the arrow in FIG. Discharge excitation is performed, whereby laser light is oscillated, and this laser light is extracted from the partial transmission mirror 19 to the outside. At this time, since the diameter of the hole 20a of the cutoff member 20 is the same as the effective diameter required for making the laser beam into a single mode, more single modes can be obtained, and the diameter of the discharge tube 12 can be changed. Become. In this state, the inner diameter of the discharge tube 12 is greatly expanded so as to be substantially the same as the inner diameter of the environment path 13 as in the above embodiment, so that a sufficient laser output can be obtained.

In addition, the separating member is not provided on the side of the partial transmission mirror 19,
It may be provided on the side of the final stage mirror 18. Further, as in the above-mentioned embodiment, an external electrode may be provided instead of the internal electrode.

As described above, according to the present invention, in any case, a structure capable of obtaining a large number of single modes without being restricted by the inner diameter of the discharge tube is realized, whereby the inner diameter of the discharge tube can be increased and a sufficient laser output can be obtained. You can get high quality CO
₂ Laser equipment can be provided.

[Brief description of drawings]

Figure 1 is a schematic diagram of a CO ₂ laser apparatus according to an embodiment of the present invention, FIGS. 2 and 3 are enlarged views, respectively the CO ₂ laser device, Figure 4 is the same CO ₂ laser device FIG. 5 and FIG. 6 are schematic views of a CO ₂ laser device showing an embodiment of the present invention and an enlarged view of main parts, and FIGS. Conventional CO ₂
FIG. 9 is a schematic diagram of a laser device and an enlarged view of a main part, FIG. 9 is a characteristic diagram of single mode and multimode with respect to Fresnel number and diffraction loss, and FIG. 10 is a characteristic diagram with respect to differential pressure of a tool blower and gas flow rate. 1,11 ...... Internal electrode, 1 '...... External electrode, 2,2', 12 ...... Discharge tube, 3,13 ...... Circulation path, 4,14 ...... Roots blower, 5,15
…… Vacuum pump, 6,7,16,17 …… Gas cooler, 8,18 ……
Final stage mirror, 9,19 …… Partial transmission mirror, 9a …… Disk part, 9b …… Ring shaped part, 20 …… Separating member, 20a …… Hole part.

Claims (2)

[Claims] 1. A carbon dioxide laser medium is circulated at high speed in a discharge tube and a circulation path connected to the discharge tube while the carbon dioxide gas laser medium is discharge-excited in the discharge tube to cause laser oscillation to generate laser light. A CO ₂ laser device extracted from a partial transmission mirror, wherein the effective diameter of at least one of the partial transmission mirror and the final stage mirror at the end position facing the partial transmission mirror is the same as the effective diameter required for making the laser light into a single mode, A CO ₂ laser device in which the diameter of the discharge tube is made larger than the effective diameter to reduce the gas flow path resistance between the discharge tube and the circulation path. 2. A carbon dioxide laser medium is rapidly circulated in a discharge tube and a circulation path connected to the discharge tube while the carbon dioxide gas laser medium is discharge-excited in the discharge tube to cause laser oscillation to generate laser light. A CO ₂ laser device taken out from a partial transmission mirror, which has a hole having the same diameter as the effective diameter required for single mode conversion between the partial transmission mirror and the final stage mirror facing the partial transmission mirror. A CO ₂ laser device in which a cutting member is provided and the diameter of the discharge tube is made larger than the effective diameter to reduce the gas flow path resistance between the discharge tube and the circulation path.