JP3131255B2 - High frequency discharge pumped three-axis orthogonal gas laser oscillator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode structure of a three-axis orthogonal gas laser oscillator, and more particularly to a high-frequency discharge excitation type three-axis orthogonal gas laser oscillator.

[0002]

2. Description of the Related Art A discharge electrode covered with a dielectric material such as a glass tube is used as a discharge-excited gas laser oscillator, particularly a high-frequency discharge-excited gas laser oscillator. The discharge electrode is orthogonal to the flow direction of the laser gas. There are known three-axis orthogonal type gas laser oscillators that are arranged facing each other.

[0003]

The discharge electrodes in the above-described three-axis orthogonal type gas laser oscillator are disposed only in regions facing each other across the laser gas passage in the glass tube and only in a part of the circumferential direction of the glass tube. The discharge between the discharge electrodes spreads to the downstream end of the discharge electrode because the electrode interval between the upstream end portion and the downstream end portion of the laser gas flow is equal. The effect causes a concentration of the electric field.

[0004] This concentration of the electric field causes local concentration of discharge in combination with the effect of the laser gas whose temperature has increased at the downstream electrode end compared to the upstream side when viewed in the flow direction of the laser gas. For this reason, in the conventional three-axis orthogonal gas laser oscillator, there is a problem that efficient discharge excitation is not performed.

In view of this, the discharge electrode is provided in the glass tube continuously over the entire circumference to form a full-circle electrode.
In other words, it is conceivable to make the electrode endless and avoid the electric field concentration at the electrode end due to the edge effect. However, in this case, the discharge between the discharge electrodes spreads unnecessarily with respect to the excitation of the laser gas, and therefore, efficient discharge excitation is not performed, and the laser generation efficiency is reduced with respect to the power injected for the discharge. , Not practical.

Further, without providing the discharge electrode over the entire circumference of the glass tube, the width of the discharge electrode in the flow direction of the laser gas is enlarged so that the electrode ends are located at positions not opposed to each other across the laser gas passage. It is possible to make it. In this case, unnecessary spread of the excitation of the discharge laser gas is reduced as compared with the entire circumference electrode, but in this case, the discharge excitation space existing upstream of the optical resonance space is increased, and the pulse is increased. In the oscillation, the falling edge of the pulse waveform of the laser is distorted, causing a problem that the pulse waveform has a tail. The tail of the pulse waveform limits the duty ratio of the pulse and limits the pulse laser output.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems in the conventional three-axis orthogonal gas laser oscillator. To perform efficient discharge excitation without causing pulsation, to obtain high laser generation efficiency with respect to the power injected for discharge, and to cause a drop in the pulse waveform of the laser in pulse oscillation. To improve the laser output with good pulse response
It is an object of the present invention to provide an axis orthogonal gas laser oscillator.

[0008]

DISCLOSURE OF THE INVENTION In view of the above-mentioned conventional problems, the present invention has a structure in which a hollow dielectric body long in a direction perpendicular to the laser gas flow direction is disposed on both sides of a laser gas passage. A high-frequency discharge-excited three-axis orthogonal type comprising a folding mirror and an output mirror for defining an optical resonance space in a direction orthogonal to the discharge direction of each discharge electrode and the laser gas flow direction arranged in each of the dielectrics. In the gas laser oscillator, each of the dielectrics is a cylinder having the same diameter, and each of the discharge electrodes is symmetrically disposed downstream from a position of an opposing axis passing through the axis of each of the dielectrics. Is provided in close contact with the inner peripheral surface of each dielectric.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 2 shows an embodiment of a high-frequency discharge excitation type three-axis orthogonal gas laser oscillator to which the electrode structure according to the present invention is applied.

The high-frequency discharge excitation type three-axis orthogonal gas laser oscillator has a laser gas passage 5 extending substantially horizontally in the left-right direction as viewed from the rectifying plate 3 in the vacuum vessel 1. A laser gas 5 such as carbon dioxide gas is circulated and supplied in the direction 5 by a blower 7. A heat exchanger 9 for cooling the laser gas is provided in the laser gas circulation path.

Above and below the laser gas passage 5, cylindrical glass tubes 11 and 13 of the same diameter as hollow dielectrics which are long in a direction perpendicular to the laser gas flow are opposed and fixedly arranged. The glass tubes 11 and 13 have a hermetically sealed structure in which atmospheric pressure is sealed. Discharge electrodes 15 and 17 are disposed inside each of the glass tubes 11 and 13 so as to oppose each other with the laser gas passage 5 vertically interposed therebetween.

As shown in FIG. 1, the discharge electrodes 15 and 17 are provided only in a part of the circumferential direction of the glass tubes 11 and 13 only in regions facing each other with the laser gas passage 5 interposed therebetween. , 17a are glass tubes 1 respectively.
The laser gas is in close contact with the inner peripheral surfaces of the laser gas channels 1 and 13 and discharges the laser gas in the laser gas passage 5 in a direction perpendicular to the left and right flow of the laser gas in the horizontal direction.

As shown in FIG. 1, the discharge electrodes 15,
Reference numeral 17 denotes the downstream side of the laser gas flow in the laser gas passage 5 from the position of the opposing axis A passing through the axis of the cylindrical glass tubes 11 and 13, that is, along the axis B symmetrically inclined to the right in the figure. The discharge electrodes 15 and 17 are arranged symmetrically and inclined with respect to each other, and the distance between the discharge electrodes 15 and 17 (the distance between the discharge surfaces 15a and 17a) is larger on the downstream side of the laser gas flow in the laser gas passage 5 than on the upstream side. The discharge area in this case is indicated by reference numeral C in the figure.

In the vacuum vessel 1, an optical resonance extending in a direction perpendicular to both the flow direction of the laser gas in the laser gas passage 5 and the discharge direction of the discharge electrodes 15, 17 ie, a direction penetrating the paper surface. Folding mirror 1 that defines space
9, an output mirror 21 is provided. In the optical resonance space defined by the folding mirror 19 and the output mirror 21, an arrangement position with respect to the discharge region C is determined so that a large gap is not formed between the return mirror 19 and the discharge region C on the upstream side in the laser gas flow direction.

According to the above configuration, the discharge electrodes 15,
Since the distance between the electrodes 17 is larger on the downstream side of the laser gas flow in the laser gas passage 5 which is the discharge excitation space, the discharge voltage between the discharge electrodes 15 and 17 is higher on the downstream side of the laser gas flow. Higher than the side. As a result, inter-electrode discharge is less likely to occur on the downstream side of the laser gas flow than on the upstream side, and accordingly, the electrode ends on the downstream side of the discharge electrodes 15 and 17 as viewed in the flow direction of the laser gas in the laser gas passage 5. The concentration of the electric field due to the edge effect is reduced. As a result, the degree of local concentration of discharge is reduced even when the laser gas whose temperature is increased flows downstream of the discharge electrodes 15 and 17 as viewed in the flow direction of the laser gas as compared with the upstream side thereof.

On the other hand, since the distance between the discharge electrodes 15 and 17 is smaller on the upstream side of the laser gas flow in the laser gas passage 5 than on the downstream side, the distance between the electrodes on the upstream side of the laser gas flow is smaller than that on the downstream side. Discharge is likely to occur, and accordingly, the concentration of the electric field due to the edge effect tends to increase at the electrode ends upstream of the discharge electrodes 15 and 17 as viewed in the flow direction of the laser gas in the laser gas passage 5. However, the temperature of the laser gas in this portion is low, and the laser gas flow is restricted by the outer peripheral surfaces of the opposed cylindrical glass tubes 11 and 13 to increase the flow velocity. It does not increase.

As a result, effective discharge can be performed without causing local concentration in the laser gas excitation by the discharge electrodes 15 and 17 in the laser gas passage 5.

[0019]

As will be understood from the above description of the embodiment, in the present invention, each of the dielectrics 11, 13 is a cylinder having the same diameter, and each of the dielectrics 11, 13 disposed in the dielectrics 11, 13 is provided. The discharge electrodes 15 and 17 are symmetrically arranged on the downstream side of the laser gas flow from the position of the opposing axis A passing through the axis of each of the dielectrics 11 and 13, and the inner peripheral surface of each of the dielectrics 11 and 13. It is closely attached to.

That is, since the dielectrics 11 and 13 have a cylindrical shape, the discharge electrodes 15 and 17 are closest to each other near the position of the opposed axis A, and the dielectrics 11 and 13 are located downstream of the laser gas flow. Are gradually separated from each other in accordance with the arc of the inner peripheral surface. Therefore, the discharge electrodes 15, 1
On the downstream side of 7, the discharge is less likely to occur than on the upstream side, and the width of the discharge electrodes 15, 17 in the gas flow direction is restricted and relatively narrow.

As described above, since the discharge electrodes 15 and 17 are closest to each other at the position of the opposed axis A, the discharge tends to be partially concentrated at the upstream end portion.
The position of the opposing axis A is the position where the dielectrics 11 and 13 are closest and the laser gas is most narrowed, and the position where the laser gas flow is the fastest.
7 is effectively cooled, and the flow rate of the laser gas excited by the discharge is large, so that the discharge is not partially concentrated.

Since the excited laser gas spreads symmetrically along the outer peripheral surface of each of the dielectrics 11 and 13, the distance between the discharge electrodes 15 and 17 is larger than the upstream end portion and the discharge distance is larger than the upstream end portion. The discharge is effectively performed without causing the concentration of the discharge even at the downstream end portion where the discharge is unlikely to occur, and the discharge is effectively performed over the entire width of each of the discharge electrodes 15 and 17 in the gas flow direction. .

In other words, by disposing the discharge electrodes in each of the cylindrical dielectric bodies on the downstream side from the opposing axis, the width of each of the discharge electrodes 15 and 17 in the gas flow direction is restricted, so that the discharge spreads more than necessary. Since it is possible to prevent and prevent the local concentration of the discharge, the optical axis can be effectively arranged in the laser gas flow excited by the discharge, and the conversion efficiency of the laser light to the discharge power can be improved, The pulse response of the laser beam can be improved.

[Brief description of the drawings]

FIG. 1 is a side view showing an embodiment of a three-axis orthogonal gas laser oscillator according to the present invention.

FIG. 2 is a schematic side view showing an embodiment of a high-frequency discharge excitation type three-axis orthogonal gas laser oscillator according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum container 5 Laser gas passage 7 Blower 11, 13 Glass tube 15, 17 Discharge electrode 19 Folding mirror 21 Output mirror C Discharge area

Claims (1)

(57) [Claims] 1. On both sides of a laser gas passage (5), hollow dielectric bodies (11, 13) which are long in a direction orthogonal to a laser gas flow direction are provided to face each other, and each of the dielectric bodies (11, 13) arranged in each of the dielectric bodies is provided. A high-frequency discharge-excited three-axis orthogonal structure including a folding mirror (19) and an output mirror (21) for defining an optical resonance space in a direction orthogonal to the discharge direction of the discharge electrodes (15, 17) and the laser gas flow direction. In the type gas laser oscillator, each of the dielectrics (11, 13) is a cylinder having the same diameter, and each of the discharge electrodes (15, 17) has an opposing axis passing through the axis of each of the dielectrics (11, 13). A high frequency discharge characterized in that the discharge electrodes (15, 17) are provided symmetrically on the downstream side from the position (A) and the discharge electrodes (15, 17) are provided in close contact with the inner peripheral surfaces of the dielectrics (11, 13). Pumped 3-axis orthogonal gas laser oscillation vessel.