JPH04246873A - Gas laser device - Google Patents

Abstract

PURPOSE:To enable a gas laser device to oscillate stably by a method wherein laser medium gas circulating inside the hermetically sealed vessel is set uniform in flow velocity. CONSTITUTION:A bypass duct 5 is provided between an inlet side and an outlet side of an axial flow fan 2 inside a hermetically sealed vessel 1, a heat exchanger 8 is provided inside the bypass duct 5, a part of laser medium gas circulated by the axial flow fan 2 is made to flow into the bypass duct 5 to be cooled down, whereby laser medium gas can be made to circulate uniformly without being lessened in flow velocity.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas laser device that outputs laser light by exciting a laser medium gas by discharge, and more particularly relates to an improvement in a gas laser device equipped with a built-in heat exchanger for removing heat generated by discharge. .

0002

[Prior Art] Generally, in a gas laser device such as a TEACO2 laser or an excimer laser that obtains a laser output by lateral discharge excitation at atmospheric pressure or high pressure, a discharge part, a blower, etc. are installed in an airtight container filled with a laser medium gas.
A heat exchanger and the like are arranged, and laser light output is obtained by discharge between a pair of main discharge electrodes provided in this discharge section and a large number of pre-ionization electrodes.

[0003] Here, the pre-ionization electrode as a discharge part is
This is to pre-ionize the laser medium gas in the discharge space before the main discharge electrode starts discharging, thereby making it easier for the main discharge to occur. In addition, the blower circulates the laser medium gas in the discharge space, removes dust generated by the discharge and impurities that interfere with laser oscillation, and ensures that a uniform glow discharge occurs between the main discharge electrodes. It is used to guide the laser medium gas whose temperature has increased to a heat exchanger to lower the laser medium gas to an appropriate temperature and to maintain the pressure in the airtight container constant. A cross-flow fan is generally used for this blower to make the airtight container compact and to circulate the laser medium gas throughout the area between the horizontally long main discharge electrodes.

[0004] Heat exchangers generally use a type that combines several fin tubes, a plate fin type, or a type made of a metal pipe with high thermal conductivity such as copper or aluminum wound in a spiral shape. For example, as disclosed in JP-A-62-111486, the arrangement is only on the suction side of the blower (see Figure 8 of the same publication) or on both the suction side and the discharge side (see Fig. 8 of the same publication). (see Figure 5).

[0005]

[Problems to be Solved by the Invention] However, when the heat exchanger is arranged as in the above-mentioned Japanese Patent Application Laid-Open No. 62-111486, it is possible to dispose the heat exchanger either on both the suction side and the discharge side of the blower, or only on the suction side. Since it is placed in the middle of the gas circulation path to the discharge section, it has the disadvantage of reducing the flow rate of the circulating gas. In particular, in laser devices such as excimer lasers that require high-speed repetitive oscillation of several hundred Hz to several thousand Hz, it is important to make the flow rate of the laser medium gas between the main discharge electrodes uniform and high. This has become one of the major issues, so in devices such as those disclosed in JP-A No. 62-111486, measures such as making the blower larger or rotating the blower faster to compensate for the reduction in gas flow velocity caused by the heat exchanger are required. It must be said that this method is completely inefficient in terms of electric power-to-light energy conversion efficiency.

Furthermore, the use of a large blower increases the size of the entire laser device, which increases the cost of manufacturing an airtight container and other components, and requires a large space when the laser device is incorporated into another device. There is a problem that this causes inconvenience. Additionally, when the blower rotates at high speeds, the load placed on its bearings increases, which increases the frequency of bearing maintenance.In the worst case scenario, the bearings or fan blades may be damaged, which may reduce the reliability of the gas laser device. .

An object of the present invention is to provide a gas laser device designed to solve the above problems.

[0008]

[Means for Solving the Problems] The present invention provides an airtight container in which a laser medium gas is sealed, a discharge section provided in the airtight container to excite the laser medium gas, and a discharge section for exciting the laser medium gas. A gas laser device comprising a once-through fan for circulation and cooling and a heat exchanger, characterized in that the heat exchanger is installed in a bypass duct provided between the suction side and the discharge side of the once-through fan. be.

[0009]

[Function] According to the present invention, a bypass duct equipped with a heat exchanger is provided between the suction side and the discharge side of the once-through fan, and a part of the laser medium gas circulated by the once-through fan is taken in and cooled. As a result, the heat generated by the discharge can be removed without reducing the flow rate of the laser medium gas.

0010

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing an example of the internal structure of the laser device of the present invention, and FIG.
It is an arrow sectional view. In the figure, 1 is an airtight container filled with laser medium gas, and 2 is a cross-flow fan installed inside the airtight container 1, whose shafts 2a and 2b are rotatable on the side walls 1a and 1b of the airtight container 1. Supported by 3 is a main discharge electrode to which a high voltage is supplied from a high voltage power source 3a. Reference numeral 4 denotes a preliminary ionization electrode, which generally generates ultraviolet rays by arc discharge, partially ionizes the laser medium gas between the main discharge electrodes 3 and 3, and causes a glow discharge between the main discharge electrodes 3 and 3. That's what I do.

A bypass duct 5 defines a space, and communicates with an opening 6 provided on the suction side of the cross-flow fan 2 and an opening 7 provided on the discharge side. Note that these openings 6 and 7 are uniformly opened in the longitudinal direction of the cross-flow fan 2, as shown in FIG. 8 is a heat exchanger installed in the bypass duct 5, and as in the conventional example, it is a type that combines several fin tubes, a plate fin type, or a spiral pipe made of a metal with high thermal conductivity such as copper or aluminum. Any type, such as one rolled into a shape, may be used.

Next, the circulation and cooling of the laser medium gas will be explained. First, by rotating the once-through fan 2 in the clockwise direction of the arrow R, the laser medium gas between the main discharge electrodes 3 and 3 is circulated in the direction of the arrow S. circulates. At this time, the flow rate of the laser medium gas is faster on the discharge side than on the suction side, so the pressure in the opening 6 on the suction side is lower than that in the opening 7 on the discharge side, and a part of the laser medium gas flows through the opening 7. After flowing into the bypass duct 5 and being cooled by the heat exchanger 8, it flows out through the opening 6 toward the discharge space such as the main discharge electrode 3. In this way, the heat exchanger 8 in the gas laser apparatus of the present invention is not placed in the middle of the circulation path of the laser medium gas as in the conventional example, so that the blowing capacity of the cross-flow fan 2 can be fully utilized without reducing the flow velocity. In addition, the laser medium gas can be cooled.

FIG. 2 shows the relationship between the repetitive oscillation frequency (Hz) and the laser output (W) at a rotation speed of 3000 rpm using the same blower fan of the present invention and the conventional example configured as described above, and the relationship between the same laser Oscillation frequency (Hz
Figure 3 shows the comparison results of the required number of revolutions (rpm) of the once-through fan in each case. As is clear from the results in FIG. 2, it can be seen that in the example of the present invention, the maximum repetition oscillation frequency can be increased, and the maximum laser output is also improved accordingly. Further, according to FIG. 3, it can be seen that the cross-flow fan can be operated at a lower rotation speed than the conventional one.

[0014]

As explained above, according to the present invention, a bypass duct equipped with a heat exchanger is provided between the suction side and the discharge side of the once-through fan, thereby reducing the amount of laser medium gas circulated by the once-through fan. Since a portion of the air is taken in for cooling, it is possible to improve the laser's repetition oscillation frequency without increasing the size of the once-through fan, and since the rotation speed of the blower can be lowered, maintenance of the blower is almost unnecessary. This makes it possible to improve the reliability of the gas laser device.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the internal structure of a laser device of the present invention.

FIG. 2 is a sectional view taken along the line AA in FIG. 1;

[Figure 3] Repetitive oscillation frequency (Hz
) and laser output (W).

FIG. 4 is a characteristic diagram showing a comparison result of the required rotation speed (rpm) of a once-through fan at the same laser oscillation frequency (Hz).

[Explanation of symbols]

1 Airtight container 2 Once-through fan 3 Main discharge electrode (discharge part) 4 Preliminary ionization electrode (discharge part) 5 Bypass duct 6,7 Opening 8 Heat exchanger

Claims (1)

[Claims] Claim 1: An airtight container in which a laser medium gas is sealed, a discharge section provided in the airtight container to excite the laser medium gas, a cross-flow fan for circulating and cooling the laser medium gas in the discharge section, and a heat exchanger. 1. A gas laser device comprising an exchanger, wherein the heat exchanger is installed in a bypass duct provided between a suction side and a discharge side of the once-through fan.