JPH0878760A - Gas laser apparatus - Google Patents

Abstract

PURPOSE: To provide a gas laser apparatus capable of amplifying laser light oscillated from an optical resonator without synchronization control. CONSTITUTION: A gas laser apparatus generates laser light by discharging and exciting a gas laser medium. The apparatus consists of a hermetic container 31 filled with a gas laser medium: a pair of main electrodes 32 oppositely positioned apart from each other in the hermetic container; a d.c. high-voltage power supply that applies high voltage between the main electrodes to strike main discharge, and that thereby discharges and excites the gas laser medium in the discharge space 33 between the main electrodes; a high-reflection mirror 35 placed on one end of the discharge space; and a window member 37 placed on the other end. In addition the gas laser apparatus is provided with an output mirror 37 that is positioned between the high-reflection mirror and the window member in the discharge space, and that forms an optical resonator together with the high-reflection mirror.

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 which excites a gas laser medium by discharge to generate laser light.

[0002]

_2. Description of the Related Art For example, in a gas laser device such as an F ₂ laser, a TEACO ₂ laser or an excimer laser, a specific output beam quality is maintained and a large amount of energy is output per pulse. May be required. As such a gas laser device, the configurations shown in FIGS. 8 and 9 are known.

The gas laser device shown in FIG. 8 comprises a laser oscillating section 1 and a laser amplifying section 2. Laser oscillating unit 1
Is a first airtight container 3 in which a gas laser medium is enclosed.
And a pair of first main electrodes 4 are arranged inside and facing each other. Further, an output mirror 6 which forms an optical resonator with the high reflection mirror 5 on one end side in the axial direction of the first airtight container 3 and the high reflection mirror 5 on the other end side is provided in an airtight manner. ing.

The first main electrode 4 is a first excitation power source section 7
It is connected to the. When a high voltage is applied to the pair of first main electrodes 4 by operating the first excitation power supply unit 5, main discharge is ignited between the main electrodes 4. Thereby,
The gas laser medium is discharge-excited to generate laser light.
This laser light is repeatedly reflected and amplified by the optical resonator,
When the intensity reaches a predetermined level, the output mirror 6 oscillates and outputs.

The laser amplifying section 2 has a second airtight container 8 in which a gas laser medium is enclosed, and a pair of second main electrodes 9 are arranged in the inside so as to face each other. Has been done. Further, window members 11a and 11b are arranged at one end and the other end in the axial direction of the second hermetic container 8 at Brewster's angle, which is a predetermined inclination angle.

The second hermetic container 8 is arranged with its axis aligned with the first hermetic container 3, and the laser light L oscillated and output from the output mirror 6 of the first hermetic container 3 is Second
The light is incident on the inside of the airtight container 8 from one window member 11a.

A second excitation power source section 12 is connected to the second main electrode 9. When the second excitation power source section 12 is activated and a high voltage is applied to the second main electrode 9, the gas laser medium in the second hermetic container 8 is excited. Therefore, the laser light L0 entering the second hermetic container 8 is amplified by the excited gas laser medium and is emitted from the other window member 11b. Thereby, the laser light L can increase the energy per pulse.

The first excitation power supply section 7 and the second excitation power supply section 12 are connected to a timing circuit 13. The timing circuit 13 controls the timing at which the excitation power supply units 7 and 12 operate. That is, the timing circuit 1
Reference numeral 3 synchronizes the timing at which the laser light L is output from the laser oscillation unit 1 and the timing at which the laser light L is amplified by the laser amplification unit 2.

However, since the voltage applied to the first main electrode 4 and the second main electrode 9 is usually as high as several tens of kV, the time control of the switching of the high voltage applied to each main electrode is extremely high. It's difficult. Therefore, the laser light L output from the laser oscillating unit 1 cannot be efficiently and surely amplified by the laser amplifying unit 2 and the energy per pulse cannot be sufficiently increased.

In order to eliminate such difficulty of control, a gas laser device shown in FIG. 9 has been proposed. It should be noted that the same parts as those of the device shown in FIG.

This gas laser device has a laser oscillating section 1A which continuously oscillates. The laser light L oscillated and output from the laser oscillating unit 1A enters the photoelectric element 14. A high voltage signal is applied to the photoelectric element 14, whereby the continuous wave laser light L0 is converted into pulses. The pulsed laser light L is incident on the laser amplification section 2, where it is amplified to a predetermined energy and output.

A driver 15 for driving the photoelectric element 14
The timing circuit 13 synchronously controls the second excitation power source 12 that applies a high voltage to the main electrode 9 of the laser amplifier 2. The operating voltage of the photoelectric element 14 is several kV
Therefore, as compared with the case where the two excitation power supply units 7 and 12 are synchronized as in the case of the gas laser device shown in FIG. 8, the synchronization control is easier.

However, when energy amplification is performed using the photoelectric element 14, the laser oscillating unit 1 capable of continuously oscillating laser light at a predetermined wavelength or its harmonics.
Not only is A required, but also the photoelectric element 14 and its driver 15 are required, which leads to an increase in the number of parts, which may result in a complicated configuration and a high cost.

[0014] On the other hand, as shown in FIG. 10, for example, F ₂
The laser light L oscillated and output from the gas laser device 10A such as a laser is supplied to the reaction chamber 21 such as a CVD chamber.
The gas is introduced through the entrance window 22 and is used to chemically react the reaction gas in the reaction chamber 21.

An excitation power supply unit 23 is connected to the gas laser apparatus 10A, and a gas operation unit 24 for supplying and discharging a reaction gas is connected to the inside of the reaction chamber 21.

By the way, the wavelength from the F ₂ laser is 157
The laser light L of nm has a transmittance of 8 with respect to the incident window 22.
It is not so high as 0%. Therefore, the energy loss in the entrance window 22 may not be negligible.
As a countermeasure against this, it is conceivable to increase the intensity of the laser light L output from the gas laser apparatus 10A. In that case, the mirrors 20a and 20b of the optical resonators provided in the gas laser apparatus 10A are considered. May be overloaded and cause early damage.

Also, the laser light L is absorbed by oxygen in the air, and energy is likely to be lost. Therefore, the gas laser device 10A and the reaction chamber 21 are connected by a light guide path 25, and the inside of the light guide path 25 is exhausted by the exhaust system 2.
At 6, the gas is exhausted to about 10 ⁻³ Torr and the laser light L is introduced into the reaction chamber 21 through the light guide path 25.

However, in that case, the need for the light guide path 25 leads to a complicated structure, and the light guide path 2 is not provided.
Since the exhaust of No. 5 must be performed, the operation at the time of use becomes complicated and it may be difficult to use.

[0019]

As described above, in the conventional gas laser apparatus, when amplifying the energy per pulse of the laser light, the synchronous control is required, and the control cannot be surely performed, or the constitution is difficult. Was complicated.

Further, when the reaction gas is chemically reacted with the laser light, the laser light is introduced into the reaction chamber through the light guide, so that the energy loss of the laser light becomes large and the structure becomes complicated. There was such a thing.

The present invention has been made based on the above circumstances, and a first object thereof is to provide a gas laser device capable of performing energy amplification of laser light without performing synchronous control. Especially. A second object of the present invention is to provide a gas laser device capable of chemically reacting a reaction gas with laser light without requiring a light guide path.

[0022]

A first means of the present invention is a gas laser device for generating laser light by exciting a gas laser medium by discharge, and is hermetically sealed with the gas laser medium. A container, a pair of main electrodes arranged to face each other in the airtight container, and a high voltage is applied between the main electrodes to ignite a main discharge to cause a gas laser in a discharge space between the main electrodes. Driving means for discharge-exciting a medium, a high-reflection mirror arranged at one end of the discharge space and a window member arranged at the other end, and the high-reflection mirror in the discharge space.
And an output mirror disposed between the window member and the high reflection mirror to form an optical resonator.

A second means of the present invention is a gas laser device for generating laser light by exciting a gas laser medium by discharge, and an airtight container in which the gas laser medium is sealed,
A pair of main electrodes arranged facing each other in this airtight container and a high voltage is applied between these main electrodes to ignite the main discharge to discharge the gas laser medium in the discharge space between the main electrodes. A driving means for exciting, a high reflection mirror arranged at one end of the discharge space and an output mirror formed at the other end to form an optical resonator, and a hollow mirror. −
A reaction container having a structure for transmitting the laser light and arranged in the optical resonator, and a reaction gas connected to the reaction container and having a reaction gas that causes a chemical reaction when irradiated with the laser light is circulated in the reaction container. And a gas supply / discharge means.

[0024]

According to the first means, the output mirror is provided in the discharge space portion at a midway portion in the optical axis direction, whereby an optical resonator for oscillating and outputting laser light in the discharge space portion and this optical resonance are provided. Since the amplifying section for amplifying the laser light output from the container is formed adjacent to each other, the laser light can be amplified without performing the synchronization control.

According to the second means, a reaction container having a structure for transmitting laser light is provided in the optical resonator, and the reaction gas is circulated in the reaction container, so that the laser light is transmitted to the optical resonator. The above reaction gas can be chemically reacted without passing through the outside.

[0026]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 show a gas laser device according to a first embodiment of the present invention, and 31 in FIG. 1 is an airtight container in which a gas laser medium is enclosed. In the airtight container 31, a pair of main electrodes 32 are arranged symmetrically with a predetermined interval about the axis O of the airtight container 31. Thereby,
Between the pair of main electrodes 32 is formed a discharge space portion 33 in which a discharge for exciting the gas laser medium by discharge is ignited.

One of the main electrodes 32 is connected to the cathode of a DC high-voltage power supply 34 as a driving means, and the other is grounded. When a high voltage is applied between the pair of main electrodes 32 by operating the DC high-voltage power supply unit 34, the main electrodes 32 are
In the meantime, the main discharge is ignited. Thereby, the discharge space 3
The gas laser medium 3 is excited by discharge and laser light L is generated with its optical axis aligned with the axis O of the airtight container 31.

The discharge space 34 is preionized by a preionization means (not shown) before the main discharge is ignited by the main electrode 32. Airtight container 3
A highly reflective mirror 35 is airtightly provided on one axial end surface of No. 1, and a window member 36 made of an optical material that transmits the laser light L is also airtightly provided on the other end surface thereof. The window member 36 is arranged at Brewster's angle.

At the axially intermediate portion of the discharge space 33,
An output mirror 37, which forms an optical resonator together with the high reflection mirror 35, is arranged. That is, the discharge space 33
Part of the optical resonator 38 by the output mirror 37.
a and the remaining portion is formed in an amplifying section 38b for amplifying the laser light L0 oscillated and output from the optical resonator section 38a.

As shown in FIG. 2, the output mirror 37 intersects at right angles with the axis O of the discharge space 33 (a region where the main discharge is ignited between the pair of main electrodes 32), that is, the optical axis direction. It is formed in a rectangular shape that is a shape corresponding to the cross-sectional shape in the direction.

In the gas laser device having such a structure, the DC high-voltage power supply section 34 is operated to operate the pair of main electrodes 32.
When a high voltage is applied in between, a main discharge is ignited between these main electrodes 32. The main discharge causes a gain for the laser oscillation in the entire discharge space 38.

In this state, the total reflection mirror 35
And an optical mirror section 38 composed of an output mirror 37
Laser oscillation occurs at a, and the laser is emitted from the output mirror 37.
The light L0 is emitted to the amplification section 38b.

The amplification section 38b, which is a section other than the optical resonator section 38a of the discharge space section 33, also has a gain for the laser light L0 due to the main discharge between the main electrodes 32. Therefore, the laser light L0 emitted from the optical resonator portion 38a to the amplification portion 38b passes through the amplification portion 38b to become the amplified laser light L, which is extracted from the window member 36. FIG. 3 shows the relationship among the discharge voltage, the gain and the laser output in the discharge space 33.

Assuming that the saturation gain in the amplifying section 38b is G and the length along the optical axis direction of the amplifying section 38b is La, the amplification factor A here is A = G · L (1) Become.

That is, according to the gas laser device having the above-mentioned configuration, it is possible to operate only one DC high-voltage power supply section 34.
Since the discharge space 33 is excited throughout, the optical resonator 38a provided in the discharge space 33 is connected to the laser cavity 38a.
The laser light L0 can be oscillated, and the laser light L0 can be amplified and taken out by the amplification section 38b also provided in the discharge space 33.

Therefore, the laser light L0 oscillated and output from the optical resonator section 38a can be amplified by the amplifying section 38b without synchronously controlling the optical resonator section 38a and the amplifying section 38b. Moreover, the oscillation and amplification of the laser light is reduced to 1
Since it can be performed in one airtight container 31, the laser oscillator and laser
The structure is simpler than the conventional structure in which the amplifier section is separate.

FIGS. 4 and 5A and 5B show a second embodiment of the present invention. The gas laser apparatus of this embodiment is, for example, an F ₂ laser, and is provided with an airtight container 41 in which a gas laser medium is sealed. Inside the airtight container 41, a pair of main electrodes 42 are provided symmetrically at predetermined intervals with respect to the axis O of the airtight container 41. One main electrode 42 is connected to the cathode of the DC high-voltage power supply unit 43, and the other main electrode 42 is grounded. As a result, a discharge space portion 44 is formed between the pair of main electrodes 42 to ignite a discharge for exciting the gas laser medium.

A highly reflective mirror 45a is provided at one end of the airtight container 41 in the axial direction, and the highly reflective mirror-4a is provided at the other end.
4 and an output mirror 45b forming an optical resonator. Inside the airtight container 41, the output mirror-4
A reaction container 46 is arranged near the inner surface of 5b.

The reaction container 46 is a hollow container having a rectangular cross section as shown in FIGS. 5 (a) and 5 (b). The discharge space 4 is formed on a pair of opposing side surfaces of the reaction container 46.
4, a window member 47 made of an optical material that transmits the laser light L generated as described later is provided in an airtight manner.

One end face of the reaction container 46 in a direction orthogonal to the side face is irradiated with laser light L to cause a chemical reaction, for example, a reaction gas introduction port 47a for photo CVD is provided. An exhaust port 47b is provided on the other end surface for exhausting the reaction gas that has chemically reacted. An introduction pipe 48a is connected to the introduction port 47a, and a discharge pipe 48b is connected to the discharge port 47b.

The introduction pipe 48a and the discharge pipe 48b are introduced into the operation portion 51 as a gas supply / discharge means. A not-shown reaction gas supply unit connected to the introduction pipe 48a is connected to the operation unit 51, and a predetermined amount of the reaction gas in the reaction container 46 is discharged to the discharge pipe 48b.
A suction pump (not shown) is connected. The reaction gas that has chemically reacted and is exhausted from the reaction container 46 by the suction pump is supplied to, for example, a CVD device (not shown).

In the gas laser device having the above structure, after the discharge space 44 is preionized by the preionization means (not shown), the DC high voltage power supply 34 is operated to apply a high voltage between the pair of main electrodes 42. The main discharge is ignited in the discharge space portion 44. As a result, the gas laser medium is excited in the discharge space portion 44, so that laser light L is generated in the discharge space portion 44.

The laser light L generated in the discharge space portion 44 is
High-reflection mirror-45a and output mirror-4 that form an optical resonator
5b repeats reflection and amplification, and when a predetermined intensity is reached, oscillation is output from the output mirror 45b.

The laser light L is repeatedly reflected by the high-reflecting mirror 45a and the output mirror 45b to pass through the reaction container 46 provided on the optical path in the optical resonator. As the laser light L passes through the reaction container 46, the reaction gas inside is irradiated, so that the reaction gas chemically reacts with the laser light L. Therefore, the chemically reacted reaction gas in the reaction container 46 is taken out from the exhaust pipe 48b.

The flow of the reaction gas is performed by the operation section 51. For example, the reaction gas may be caused to chemically react by irradiating with the laser light L while flowing a predetermined amount at a time, or a predetermined amount of the reaction gas may be stored in the reaction container 46 and chemically reacted. Good.

According to the gas laser apparatus having such a structure, since the reaction container 46 is provided in the optical resonator of the airtight container 41, the reaction gas in the reaction container 46 is subjected to the photoinduced chemical reaction. Moreover, it is not necessary to guide the laser light L to the outside of the optical resonator. Therefore, as in the conventional case where the laser light L is introduced into the reaction vessel through the light guide path,
Since there is almost no energy loss until the laser light L enters the reaction container 46, the chemical reaction of the reaction gas can be efficiently performed.

Further, the reaction container 4 provided in the optical resonator
The intensity of the laser light L in the optical resonator is lowered by allowing the laser light L to pass through 6 and causing a chemical reaction. Therefore, the thermal load on the high-reflecting mirror 45a and the output mirror 45b forming the optical resonator is reduced, so that the life of these mirrors can be extended, especially for promoting a chemical reaction. This is effective when the output of the laser light L is increased.

FIG. 6 shows a third embodiment of the present invention. Since this embodiment is a modification of the second embodiment shown in FIGS. 4 and 5A and 5B, the same parts are designated by the same reference numerals and the description thereof will be omitted.

That is, in the third embodiment, not only is the reaction container 46 (internal reaction container) arranged in the optical resonator, but also on the outer surface side of the output mirror 45b and on the outer surface thereof. A reaction container 46A (referred to as an external reaction container) is arranged with its side surfaces joined.

According to such a configuration, the internal reaction container 4
The reaction gas in 6 induces a chemical reaction by the laser light L amplified in the optical resonator, and the reaction gas in the external reaction vessel 46A chemically reacts by the laser light L oscillated and output from the optical resonator. The reaction is triggered. Therefore, not only the photo-induced chemical reaction of the reaction gas can be performed in two steps, but also different kinds of reaction gases can be introduced into the respective reaction vessels 46 and 46A to cause a chemical reaction.

FIG. 7 shows a fourth embodiment of the present invention. In this embodiment, the reaction vessel 46 shown in the second embodiment is incorporated into the gas laser apparatus of the first embodiment, and the operation part 51 controls the flow of the reaction gas.
In this embodiment, the same parts as those in each of the above-mentioned embodiments are designated by the same reference numerals and the description thereof will be omitted.

That is, in the fourth embodiment, the reaction container 46 is arranged inside the window member 36. Thereby, the reaction gas in the reaction container 46 can be chemically reacted by the laser light L amplified by the amplification section 38b.

In the fourth embodiment, the reaction container 46 may be arranged inside the optical resonator portion 38a. In addition, in the second to fourth embodiments, the reaction container 4
When oxygen is circulated as a reaction gas in 6, 46A, ozone is generated by the oxygen reacting with the laser light and chemically reacting with the laser light, so that the gas laser device can be used as an ozonizer device.

[0054]

As described above, according to the present invention, the high reflection mirror is arranged on one end side of the discharge space and the window member is arranged on the other end side thereof, and the light is reflected by the high reflection mirror between them. An output mirror forming a resonator is arranged, and the laser light oscillated and output from the optical resonator is amplified in a portion of the discharge space between the output mirror and the window member. .

Therefore, the laser light oscillated and output from the optical resonator can be amplified and taken out from the window member without controlling the oscillation output and the amplification of the laser light synchronously.
Further, according to the present invention, a reaction container having a hollow structure for transmitting laser light is provided in the optical resonator, and a gas is circulated in the reaction container to induce a chemical reaction by the laser light. I chose

Therefore, since it is not necessary to introduce the laser light into the reaction vessel through the light guide path as in the conventional case, the construction of the entire apparatus is simplified, the operability is improved, and the optical resonator is provided. In some cases, the load on the mirror to be formed can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a gas laser device according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a graph showing a relationship among a discharge voltage, a gain and a laser output in the discharge space portion.

FIG. 4 is a schematic configuration diagram showing a gas laser device according to a second embodiment of the present invention.

5A is a vertical cross-sectional view of the reaction container, and FIG. 5B is a side view of the same.

FIG. 6 is a schematic configuration diagram showing a gas laser device according to a third embodiment of the present invention.

FIG. 7 is a schematic configuration diagram showing a gas laser device according to a fourth embodiment of the present invention.

FIG. 8 is a schematic configuration diagram showing a conventional gas laser device.

FIG. 9 is a schematic configuration diagram showing another conventional gas laser device.

FIG. 10 is a schematic configuration diagram showing still another conventional gas laser device.

[Explanation of symbols]

31, 41 ... Airtight container, 32, 42 ... Main electrode, 33, 4
4 ... Discharge space part, 34, 44 ... DC high voltage power supply part (driving means), 35, 45a ... High reflection mirror, 36 ... Window member, 3
7, 45b ... Output mirror, 46 ... Reaction container, 51 ... Operation part (gas supply / discharge means).

Claims (6)

[Claims] 1. A gas laser apparatus for generating laser light by exciting a gas laser medium by electric discharge, and an airtight container in which the gas laser medium is enclosed, and the airtight container is disposed so as to be opposed to and spaced from the airtight container. A pair of main electrodes, driving means for applying a high voltage between the main electrodes to ignite a main discharge to excite the gas laser medium in the discharge space between the main electrodes by discharge, and the discharge space. Of the high reflection mirror arranged on one end side and the window member arranged on the other end side, and the high reflection mirror arranged between the high reflection mirror and the window member in the discharge space portion. A gas laser device comprising an output mirror forming a resonator. 2. The gas laser device according to claim 1, wherein the output mirror has substantially the same cross-sectional shape in a direction intersecting the optical axis direction of the discharge space. 3. A reaction container having a hollow structure for transmitting laser light is disposed inside the window member in the discharge space, and the reaction container is internally irradiated with the laser light. 2. A gas supply / exhaust means for circulating a reaction gas which causes a chemical reaction by being connected is connected.
The gas laser device described. 4. A gas laser device for generating discharge laser light by exciting a gas laser medium by discharge, and an airtight container in which the gas laser medium is enclosed, and the airtight container is disposed so as to be opposed to and spaced from the airtight container. A pair of main electrodes, driving means for applying a high voltage between the main electrodes to ignite a main discharge to excite the gas laser medium in the discharge space between the main electrodes by discharge, and the discharge space. The output mirror that forms an optical resonator with the high-reflection mirror disposed on one end side and the high-reflection mirror disposed on the other end side, and a hollow structure for transmitting laser light are provided. It is provided with a reaction container arranged in the optical resonator, and a gas supply / exhaust means connected to the reaction container and flowing therein a reaction gas which causes a chemical reaction by being irradiated with the laser light. Gas laser device characterized by the following. 5. The gas laser apparatus according to claim 4, wherein a reaction vessel is arranged outside the output mirror and joined to an outer surface of the output mirror. 6. The gas laser according to claim 4, wherein oxygen which generates ozone by being irradiated with laser light to cause a chemical reaction is circulated in the reaction vessel. apparatus.