JPH0818133A - Gas pulse laser - Google Patents

Abstract

PURPOSE:To realize reduction in size of the apparatus by moving, without using a fan, the gas within the space defined by the first and second main electrodes to a stylus electrode before the time to apply the voltage of the next period has come. CONSTITUTION:A periodical voltage is applied across preliminary ionizing electrodes 103, 113 and main electrodes 120, 121 and thereby discharge occurs in the space defined by the main electrodes 120, 121. This discharge excites the gas within the vessel and the light beam generated from the gas is reflected by mirrors 6, 7 forming resonator and is then emitted as the laser beam to the external elements of the gas pulse laser. An aperture electrode 114 has an aperture exposed to the space defined by the main electrodes 120, 121. When the predetermined voltage is applied to a stylus electrode 118, the gas ionized in the vicinity of the end part of the stylus type electrode 118 directed to the aperture moves toward the aperture with a Coulomb's force. Therefore, the gas circulates within the gas pulselaser passing through the aperture.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas pulse laser such as a carbon dioxide gas laser, an excimer laser and a nitrogen laser.

[0002]

2. Description of the Related Art A general gas pulse laser is operated by a so-called transverse discharge (TEA discharge). This gas pulse discharge is usually a glow discharge that occurs between the laser main electrodes, and this pulse discharge is performed orthogonal to the optical axis of the laser light emitted from the gas pulse laser. The surface of the laser main electrode is sputtered by the discharge, and the gas existing between the laser main electrodes by the next pulse discharge contains impurities due to sputtering or the like.
The impurities present in this gas deteriorate the output characteristics of the laser light. In order to operate the pulse discharge repeatedly,
Usually, a gas circulation device (cross flow fan) is installed in the laser tube. The cross flow fan is connected to a motor outside the laser tube via a rotor that uses a magnet or the like, and this motor is driven at high speed (1000 to 3000).
When it is driven to rotate at (rpm), the cross flow fan is rotated and the gas inside the electrode circulates. Therefore, the gas existing between the main electrodes is always replaced with a clean gas, and the output reduction of the laser light output from the gas pulse laser is prevented.

An excimer laser device that circulates gas using such a fan is described in Japanese Patent Laid-Open No. 5-299723.

[0004]

However, in the gas pulse laser using the conventional fan, since the vibration accompanying the rotation of the fan is transmitted to the gas pulse laser itself by rotating the fan at a high speed, this gas pulse laser is used. There is a problem in that the emission direction of the laser light output from the laser shifts. Moreover, such a fan is as large as a gas pulsed laser, and the device for driving this fan is complicated. Therefore, the size of the conventional excimer laser device has reached a total length of 1 meter. The inventors of the present application have developed a gas pulse laser having a structure in which the total length of the gas pulse laser is about 30 cm and the emitting direction of the laser light emitted from the gas pulse laser is constant with high accuracy. I went. In this development, the fan was the cause of the vibration of the gas pulse laser, and the most obstacle to the miniaturization of the gas pulse laser. However, if this fan is removed, the output of the laser light emitted from this gas pulse laser will be reduced as described above.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a gas pulse laser having a completely new structure and a reduced size.

[0006]

The present inventors have developed a novel gas pulse laser which solves the above-mentioned problems. This gas pulse laser is an excimer laser and has a total length of 3
It has a structure in which the emitting direction of the laser light is approximately 0 cm and is constant with high accuracy. This is so small that it cannot be compared with a conventional laser having a total length of 1 meter, and the noise during driving is quiet. This gas pulse laser has a container for containing a gas serving as a laser medium,
In order to excite this gas, a main electrode is arranged in the container with a predetermined space between them, a mirror that is arranged to face the space with a space to form a resonator, and is electrically connected to the main electrode. A preliminary ionization electrode arranged in the vicinity of this main electrode,
An opening electrode, which is electrically connected to the preionization electrode and has an opening that looks into the space, and a needle-shaped electrode whose longitudinal direction faces the opening direction of the opening electrode. The excimer laser developed by the present invention can be applied to other gas pulse lasers such as carbon dioxide laser. Further, the preionization electrode and the opening electrode may be integrated.

When this main electrode is used as a first and a second main electrode, the present invention provides a gas having a container for containing a gas and first and second main electrodes arranged to face each other in the container. The target is a pulsed laser, and the needle-shaped electrode may be arranged with its longitudinal direction oriented in a direction toward a space sandwiched between the first main electrode and the second main electrode. .

Further, the present invention is generated by exciting a gas by applying a periodic voltage to the container for the gas to enter and the first and second main electrodes arranged to face each other in the container. The present invention is also intended for a gas pulse laser that resonates light and emits it as laser light. The gas existing in the space sandwiched between the first main electrode and the second main electrode in the first cycle is described below. A sufficient number of needle-shaped electrodes may be arranged in the container so as to be moved by the voltage application time of the period.

[0009]

Function: A periodic voltage is applied between the preionization electrode and the main electrode to cause discharge in the space sandwiched by the main electrodes.
Due to this discharge, the gas inside the container is excited and the light generated from the gas is reflected by the mirror that constitutes the resonator and emitted to the outside of this gas pulse laser as laser light.
The opening electrode has an opening that looks into the space sandwiched by the main electrodes, and when a predetermined voltage is applied to the needle electrode, it is ionized near the tip of the needle electrode facing this opening direction. The generated gas moves toward this opening due to the Coulomb force. Therefore, since the gas circulates inside the gas pulse laser through the opening, the fan which has been necessary in the past is unnecessary. That is, since the gas existing in the space sandwiched between the first main electrode and the second main electrode in the first cycle is moved by the needle-shaped electrode by the voltage application time of the next cycle, The conventional fan is unnecessary, and the entire device can be downsized.

This opening is defined by a plurality of through-holes which extend through the opening electrode from the opening electrode in the spatial direction and which are arranged in the same penetrating direction. As the shape of such an opening, a circular shape or a honeycomb shape is enumerated. Here, since the directions of the through holes are aligned, the directivity and uniformity of the air flow are high, and stable laser light can be emitted. Further, this opening may be defined by a mesh electrode. The mesh electrode is easier to manufacture than the above-mentioned through holes, and the manufacturing time of the present laser can be shortened.

[0011]

EXAMPLES Examples of the gas pulse laser according to the present invention will be described below. In the description, the same elements will be denoted by the same reference symbols, without redundant description.

FIG. 1 is a partially exploded perspective view of an excimer laser according to an embodiment of the present invention, showing the appearance of the excimer laser. This excimer laser has a container in which both ends of a metal or glass discharge tube 1 into which a gas serving as a laser medium enters is sealed with metal sealing plates 2 and 3. The discharge tube 1 and the sealing plates 2 and 3 have sealing plates 2 and 3 at both open ends of the discharge tube 1 so as to sandwich the discharge tube 1 therebetween.
And fixing bolts 4a to 4d penetrating the sealing plate 3 are fixed to the sealing plate 3 by screwing. A through hole is formed in the center of the sealing plate 2, and the output mirror fixture 5 is attached so as to cover the open end surface of the through hole. The fixture 5 has a cylindrical shape, and the output mirror 6 is fitted and fixed to the inner wall of the fixture 5. A reflection mirror 7 is fixed to the sealing plate 3 at a position facing the output mirror 6, these mirrors 6 and 7 constitute a resonator of a laser, and laser light is emitted from the output mirror 6. .

A discharge device 100 is installed inside the discharge tube. Current introducing terminals 9 and 8 are installed on the sealing plates 2 and 3 so as to penetrate the sealing plates 2 and 3, respectively. A voltage of + HV is applied to the current introduction terminal 9 to supply a current to the main electrode and the preliminary ionization electrode in the discharge device 100 described later. A voltage of -HV is also applied to the current introducing terminal 8 to supply a current to the needle electrode in the discharge device 100 described later.

FIG. 2 is a front view of the excimer laser shown in FIG. 1 as seen from the direction of arrow A in FIG.
FIG. 3 is a side sectional view of the excimer laser shown in FIG. 1, taken along the line BB in the figure. Further, FIG. 4 is a perspective view showing a structure of a discharge device 100 which is a main part of the excimer laser shown in FIG. In the following description, the terms "upper" and "lower" are based on the upper and lower parts of FIG.

A discharge device 100 is installed in the discharge tube 1 forming the container. The discharge device 100 includes a first main electrode 120, a second main electrode 121, and a preionization electrode 11
2, 113; 102, 103; aperture electrodes 104, 114
And a needle electrode 118. A gas serving as a laser medium is sealed inside the discharge tube 1.

The sealing plate 2 has a metal support 10 having an L-shaped cross section.
One side of 1 is fixed. A metal support 301 having an L-shaped cross section is also fixed to the sealing plate 3 so as to face the support 101. A metal support plate 101a is fixed to the other surface of the support tool 101.
a is fixed to the other surface of the support member 310. Therefore, the support plate 101a is arranged along the longitudinal direction of the discharge tube 1,
It is laid horizontally between the supports 101 and 301. The main electrode 120 is fixed to the lower surface of the support plate 101a and is connected to the sealing plates 2 and 3.

The main electrode 121 is arranged at a position facing the main electrode 120. The main electrode 121 is fixed to the metal plate 107. The metal plate 107 is arranged in the longitudinal direction of the discharge tube 1. Capacitors 106 and 116 are fixed to the metal plate 107 so as to sandwich the metal plate 107. On the metal plate 107, a plurality of pairs of capacitors 106 and 116 are aligned and fixed in the longitudinal direction of the discharge tube 1. A pair of capacitors 106 and 116 arranged at both ends of the metal plate 107 is fixed to the capacitor support 115. Each support tool 115 is fixed to the sealing plate 2 and the sealing plate 3. As described above, the main electrodes 120, 12
1 and the capacitors 106 and 116 are supported by the sealing plates 2 and 3, and the main electrodes 120 and 121 are arranged with a predetermined space therebetween in order to excite the gas in the discharge tube 1. .

The opening electrode 114 is interposed and fixed between the capacitor 116 and the support 115, and the main electrode 1
21 is electrically connected. The opening electrode 114 is arranged near the main electrode 121. A flat plate-shaped preionization electrode 113 is fixed to the upper end of the opening electrode 114. A flat plate-shaped preionization electrode 112 is fixed to the support plate 101a, and the preionization electrode 112 and the preionization electrode 113 are arranged with a slight gap. Therefore, when a voltage is applied to the opening electrode 114, the gap between the preionization electrode 112 and the preionization electrode 113 is narrow, so that a discharge is easily generated between them and discharge between the main electrodes 120 and 121 is easily generated. The opening electrode 114 has an opening 11 that looks into the space between the main electrode 121 and the main electrode 120.
Have nine. The opening 119 has a through hole 11 penetrating the opening electrode 114 from the opening electrode 114 in the space direction.
9 is defined. The opening electrode 104 is interposed and fixed between the capacitor 106 and the support 105, and is electrically connected to the main electrode 121. The structure of the opening electrode 104 is similar to that of the opening electrode 114.

The metal plate 107 is connected to the current introducing terminal 9 penetrating the sealing plate 2 and is given a negative potential.
Although the current introducing terminal 9 penetrates the sealing plate 2,
Is insulated from. The main electrode 120 is grounded to the case. On the other hand, between the sealing plate 2 and the sealing plate 3,
The metal rod 117 is horizontally installed. Metal rod 117
Are electrically connected to the current introduction terminal 8. The current introducing terminal 8 penetrates the sealing plate 3, but is insulated from the sealing plates 2 and 3. The current introduction terminal 8 and the metal rod 1
It may be integrated with 17. A negative potential is applied to the current introducing terminal 8 to supply a current. Metal rod 11
A plurality of needle-shaped electrodes 118 are fixed to 7. The needle electrode 118 is arranged such that its longitudinal direction faces the opening direction of the opening electrode 114. A plurality of needle-shaped electrodes 118 are provided on the metal rod 117, and the openings 11 of the opening electrodes 114 are formed on the metal rod 117.
It is fixed corresponding to 9.

Next, the operation and drive circuit of this excimer laser will be described. FIG. 5 is an explanatory diagram showing an electrical connection of each element of the excimer laser shown in FIG. 2 and a drive circuit for driving the same, in which an outline arrow indicates circulation of gas serving as a laser medium. Shows the direction.

The main electrode 120 is connected to the ground, the main electrode 121 is connected to the LC circuit as shown in the drawing, and a voltage of -HV is applied via the current introducing terminal 9.
A periodic voltage is applied between the preionization electrodes 102, 112; 103, 113 and the main electrodes 120, 121, and a discharge is generated in the space sandwiched between the main electrodes 120, 121.
Due to this discharge, the gas inside the discharge tube 1 is excited to generate light. This light is reflected by the mirrors 6 and 7 constituting the resonator and resonates, and emitted as laser light to the outside of the excimer laser via the output mirror 6. In other words, the preliminary ionization electrodes 112, 113; 102, 103 and the main electrodes (discharge electrodes) 120, 121 function as a laser discharge circuit. When a pulse voltage is applied to the terminal 9, a glow discharge having a period of several tens to several hundreds nsec occurs between the main electrodes 120 and 121 due to the electric energy pulse-charged in the capacitors 106 and 116. The laser gas serving as the laser medium is excited by this glow discharge. This excimer laser can be repeatedly operated. Ions generated by the pulse discharge and residual products generated by the sputtering of the main electrodes 120 and 121 are the main electrodes 12.
If it remains between 0 and 121, the local spatial homogeneity of the discharge is impaired until the next pulse discharge due to this residual product. This discharge shifts to an unstable arc discharge to increase the instability for each pulse, and finally the laser oscillation stops. The excimer laser of the present embodiment exhausts the gas between the main electrodes 120 and 121 before the next pulse discharge starts, and supplies the gas without residue to the space between the main electrodes 120 and 121 by the needle electrode 118. You can
The needle-shaped electrode 118 is formed from the needle-shaped electrode 118 to the main electrode 12.
A gas flow is generated in the direction of the region sandwiched between 0 and 121.

Since a potential of -HV is applied to the needle-shaped electrode 118 and the needle-shaped electrode 118 faces the direction of the opening 119, the gas ionized near the tip of the needle-shaped electrode 118 is directed toward the opening 119 by the Coulomb force. Move to. Therefore, the gas that has passed through the opening 119 is not allowed to pass through the main electrodes 120 and 121.
The discharge tube 1 passes through the space sandwiched by
It will circulate inside. As a result, the gas existing in the space sandwiched between the main electrode 120 and the main electrode 121 in the first cycle is moved by the voltage application time of the next cycle. This gas flow is generated by the opening 1 of the opening electrode 114.
It is created by the corona discharge that occurs between 19 and the needle electrode 118. This creates a force that causes a flow of ions to be generated and move the gas. Aperture electrode 11
Since No. 4 is grounded via the preionization electrodes 112 and 113, when a negative voltage is applied to the needle electrode 118, it is generated by corona discharge generated between the needle electrode 118 and the opening electrode 114. Negative ions move from the needle-shaped electrode 118 toward the opening electrode 114. In addition, the needle electrode 11
By applying a positive voltage to 8, it is possible to generate a gas flow in the clockwise direction in FIG.

In the excimer laser of this embodiment, the gap distance formed between the needle electrode 118 and the opening electrode 114, the shape and size of each of the electrodes 114 and 118, and the value of the high voltage are appropriate. It is possible to set the gas flow rate in accordance with the desired oscillation repetition rate (times / second).

The axis of the needle electrode 118 has an opening 119.
If it coincides with the axis of, the opening electrode 114 and the needle electrode 11
Since the electric field strength generated between the corona discharges 8 and 8 is uniformly distributed around this axis, the electric field strengths are evenly generated with respect to this central axis of the corona discharge. However, the electric field distribution may change depending on the shape of the needle-shaped electrode 118 or the shape of surrounding members, and ion flow may actually be hindered. Therefore, the needle-shaped electrode is not necessarily arranged on the central axis. Is not always the most effective.

According to the excimer laser of this embodiment, since the conventional fan is not required because the needle electrode 118 is provided, the size of the entire apparatus can be reduced, and the vibration by the fan does not occur, so that the emitting direction is stable. Laser light can be emitted.

The present invention is not limited to the above-mentioned embodiment, but various modifications can be made.

FIG. 6 is a perspective view showing the structure of a main part of an excimer laser according to another embodiment of the present invention by partially breaking it, and an opening electrode 214 having a honeycomb-shaped through hole is shown. ing. That is, in this embodiment, the opening 119 shown in FIG. 2 is defined by a plurality of through holes arranged in the same penetrating direction. This penetrating direction is a direction in which a space between the opening electrode 214 and the main electrodes 120 and 121 is desired. With such a configuration, it is possible to enhance the directivity and uniformity of the air flow, so that stable laser light can be emitted.

FIG. 7 is a perspective view showing the structure of a main part of an excimer laser according to another embodiment of the present invention by partially breaking it, showing an opening electrode 314 having a wire mesh attached thereto. There is. In this embodiment, the opening 119 shown in FIG. 2 is defined by a mesh electrode. The mesh electrode is easier to manufacture than the through hole 119 shown in FIG. 4, and the manufacturing time of the excimer laser can be shortened. The excimer laser developed by the present invention can be applied to other gas pulse lasers such as carbon dioxide laser.

[0029]

As described above, according to the present invention, the conventional fan is unnecessary and the entire apparatus can be downsized. When a prototype excimer laser is manufactured, its total length is about 30 cm. This is so small that it cannot be compared with a conventional laser having a total length of 1 meter, and the noise during driving is quiet. Further, since a fan is not required, the vibration of the gas pulse laser itself by this fan is remarkably reduced, a stable laser beam in the emitting direction can be emitted, and a device for eliminating this oscillation is also unnecessary.
Furthermore, since a fan is not used, a motor for driving this fan is unnecessary, and the power consumption of this gas pulse laser can be reduced. That is, the gas flow generation mechanism of the gas pulse laser of the present invention consumes several watts of power, and consumes 1/100 of the power when using a fan. Since this needle-shaped electrode can also function as an electrostatic precipitator, the gas pulse laser of the present invention prevents the output of the laser light emitted by the impurities generated in the container adhering to the mirror and the like. be able to.

[Brief description of drawings]

FIG. 1 is a partially exploded perspective view of an excimer laser according to an embodiment of the present invention, showing an appearance of the excimer laser.

FIG. 2 shows the excimer laser shown in FIG.
It is the front view seen from the direction.

3 is a side sectional view of the excimer laser shown in FIG. 2 taken along the line BB in FIG.

FIG. 4 is a perspective view showing a configuration of a main part of the excimer laser shown in FIG. 1 by partially breaking it.

5 is an explanatory diagram showing an electrical connection of each element of the excimer laser shown in FIG. 2 and a drive circuit for driving the same, in which white arrows indicate circulation of gas serving as a laser medium. Shows the direction.

FIG. 6 is a perspective view showing a configuration of a main part of an excimer laser according to another embodiment of the present invention by partially breaking it, showing a preionization electrode having a honeycomb-shaped through hole formed therein.

FIG. 7 is a perspective view showing a configuration of a main part of an excimer laser according to another embodiment of the present invention with a part thereof cut away, showing a preliminary ionization electrode having a wire mesh attached thereto.

[Explanation of symbols]

120, 121 ... Main electrode, 112, 113, 102, 1
03 ... Pre-ionization electrode, 114 ... Opening electrode, 118 ... Needle electrode.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location H01S 3/22 3/225 H01S 3/03 J 3/22 Z 3/223 E

Claims (5)

[Claims] 1. A container for containing a gas serving as a laser medium, a main electrode arranged in the container at a predetermined space to excite the gas, and a main electrode arranged to face each other at the space. A mirror constituting a resonator, a preionization electrode electrically connected to the main electrode and arranged in the vicinity of the main electrode, and a preionization electrode electrically connected to the preionization electrode and looking into the space. A gas pulse laser comprising: an aperture electrode having an aperture; and a needle-shaped electrode whose longitudinal direction is arranged facing the aperture direction of the aperture electrode. 2. The gas pulse laser according to claim 1, wherein the opening is defined by a plurality of through-holes that extend through the opening electrode from the opening electrode in the space direction and have uniform through-hole directions. . 3. The gas pulse laser according to claim 1, wherein the opening is defined by a mesh electrode. 4. A gas pulse laser comprising a container for containing a gas and first and second main electrodes arranged to face each other in the container, wherein the first main electrode and the second main electrode are provided. A gas pulse laser comprising a needle-shaped electrode whose longitudinal direction is arranged in a direction toward a space sandwiched between the electrode and the electrode. 5. Light generated by exciting the gas by applying a periodic voltage to a container for the gas to enter and first and second main electrodes arranged to face each other in the container. In a gas pulse laser that resonates and emits as laser light, the gas existing in a space sandwiched between the first main electrode and the second main electrode in a first cycle is applied with a voltage in the next cycle. A gas pulse laser characterized in that a sufficient number of needle-shaped electrodes are arranged in the container so as to be moved by time.