JP2003008113A - Metal vapor laser - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metal vapor laser that can maintain stable laser oscillation for a long time by suppressing deterioration of the laser a beam transmittance and increase in the thermal lens actions of the laser beam transmitting windows for a long time. SOLUTION: This metal vapor laser is provided with a discharge tube 1 supplied with a gas for electric discharge, window fixing tubes 8 and 9 which are respectively coupled with the opened end sections of the tube 1 and extended outward, and the laser light transmitting windows 10a and 10b respectively attached to the outside opened end sections of the tubes 8 and 9. This laser is also provided with electrodes 3 and 4 for supplying discharge voltages at both end sections of the discharge tube 1. The laser obtains laser light by generating a metal vapor by vaporizing a vapor-source metal placed in the discharge tube 1 by heating the inside of the tube 1 by causing electric discharge. In the window fixing tubes 8 and 9, at least one or more light-transmissive metal vapor shield plate 24 and 24a-24c having prescribed thicknesses are installed with prescribed intervals from the internal surfaces of the laser light transmitting windows 10a and 10b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal vapor laser device, and more particularly to a reduction of the laser light transmittance of the window and a thermal lens effect due to the metal vapor adhering to the laser light transmitting window during long-time operation. The present invention relates to a structure that suppresses and maintains the stability of laser oscillation characteristics for a long time.

[0002]

2. Description of the Related Art FIG. 5 is a schematic view showing an example of a known general metal vapor laser device. In the figure, an anode 3 and a cathode 4 are provided at both ends of a cylindrical ceramic tube 2 in which a plurality of vapor source metals 11 are installed. Between the electrodes forming the anode 3 and the cathode 4, a heat insulating material 5 provided so as to surround the ceramic tube 2 described above, an insulating tube 6 covering the outer periphery of the heat insulating material 5, and the insulating tube 6 And a conductive outer tube 7 for supporting the discharge tube 1
And a pair of window fixing tubes 8 and 9 are attached to the outer sides of both electrodes in the axial direction.

The outer cylinder 7 has a length of approximately 2 at the center in the longitudinal direction in order to apply a predetermined operating voltage between the anode 3 and the cathode 4.
It is divided and functions as a flange for voltage supply. Further, at the outer opening end portions of the pair of window fixing tubes 8 and 9,
Laser light transmission windows 10a and 10b through which laser light enters and exits
Is hermetically attached, and a pair of mirrors (not shown) forming an optical resonator is provided outside the windows 10a and 10b.

In such a metal vapor laser device, after a discharge buffer gas having a predetermined pressure is introduced into the discharge tube 1, a gap between the voltage supply flange on the cathode 4 side and the voltage supply flange on the anode 3 side is provided. Then, a high-speed pulse high voltage is applied from the high-speed pulse power source 21 with the pulse shaper 22. That is, in synchronization with the pulse timing signal from the pulse shaper 22, the high-speed pulse power supply 21 outputs a pulse high voltage having a high repetition frequency.

Hereinafter, the discharge plasma generated in the discharge tube 1 heats the inside of the discharge tube 1 to a high temperature, and the vapor source metal 11 produces vaporized metal particles such as copper as a laser medium, that is, metal vapor, and thereafter. , Metal vapor is excited by free electrons in the discharge plasma diffused in the discharge tube 1,
Laser light is oscillated when the excited metal vapor makes a transition to a low energy level.

In this way, the laser light is oscillated,
The metal vapor evaporated from the vapor source metal 11 fills the inside of the ceramic tube 2 which is the main part of the discharge tube 1, and, although in a small amount, the inner surface of the window fixing tubes 8 and 9 and the laser light transmitting window 1.
Diffuse or scatter and adhere to the inner surfaces of 0a and 10b.
Although a small amount of metal vapor adheres to the laser light transmitting windows 10a and 10b, the metal vapor laser device is operated for a long period of time, and as a result, as shown in FIG. The metal vapor is accumulated, and the metal film 23 has a thickness that cannot be ignored in view of the operating characteristics of the metal vapor laser device.
Will be deposited as.

As shown in FIG. 6, a window 1 for transmitting a laser beam is provided.
The metal film 23 attached to the layers 0a and 10b absorbs a part of the laser light and, as described below, reduces the transmittance of the laser light, increases the thermal lens action, etc. The adverse effect on it cannot be ignored.

FIG. 7 shows windows 10a and 10b for transmitting laser light.
3 is a graph showing the degree to which the metal film 23 attached and accumulated on the window changes the transmittance of laser light through these windows themselves.
As is clear from FIG. 7, the transmittance of the laser light is reduced by about 0.2% after operating for about 1000 hours, for example. When the thickness of the metal film 23 attached to the laser light transmitting windows 10a and 10b increases, the laser light transmitting window 10
It goes without saying that the light intensity of the laser light entering and exiting a and 10b further decreases.

Further, the deposited and accumulated metal film 23
As a result, the temperature of the laser beam transmitting windows 10a and 10b further rises due to the fact that the laser beam and the infrared rays emitted from the high temperature discharge tube, that is, the ceramic tube 2 are absorbed.

Further, the adhesion thickness of the metal film 23 on the laser beam transmitting windows 10a and 10b tends to be thicker in the central portion of the window than in the peripheral portion, but ignoring this, the metal film 23 is ignored. Two
Even if the adhesion thickness of 3 is evenly distributed over the entire inner surface of the window, the central portion of the window, which is the main optical path of the laser beam, is bonded to the window fixing tubes 8 and 9, and the heat is dissipated. The temperature at the time of operation becomes higher than that at the peripheral portion that is easily affected.

In this way, the metal vapor is transmitted through the laser light transmission windows 10a and 10b together with the oscillation operation time of the laser device.
When adhered to and accumulated in, the temperature difference between the central portion and the peripheral portion of the laser light transmitting window is related to the light intensity of the transmitted laser light,
As shown in FIG. As is clear from FIG. 8, the greater the light intensity of the transmitted laser light, the larger the temperature difference between the central portion and the peripheral portion of the laser light transmitting windows 10a and 10b as the operating time of the laser device increases. Become.

Then, the laser beam transmitting windows 10a and 10b.
In addition, when a temperature distribution is generated in which the central portion is high in temperature and the peripheral portion is low in temperature, a non-uniform distribution of refractive index occurs in, for example, quartz glass which is a material of the laser light transmitting windows 10a and 10b,
A convex lens effect, that is, a thermal lens effect, which gives the converging property to the transmitted laser light occurs. Therefore, as shown in FIG. 9, as the light intensity of the laser light increases, the focal length of the laser light transmitting windows 10a and 10b formed into convex lenses decreases with the length of the operation time. This means that the windows 10a, 10b
It means that the parallelism of the laser light entering and exiting is reduced.

[0013]

As described above, the adherence of metal vapor to the laser light transmitting window has a small effect in a relatively short time operation, but in a long time operation,
There is a problem that the transmittance of the laser light is reduced and the thermal lens action is increased, which adversely affects the output laser light.

An object of the present invention is to suppress a decrease in the laser light transmittance of the laser light transmitting window and an increase in the thermal lens action for a long time, and to maintain a stable laser oscillation operation for a long time. To provide.

[0015]

DISCLOSURE OF THE INVENTION The present invention is directed to a discharge tube to which a discharge gas is supplied, a window fixing tube connected to an open end of the discharge tube and extended outward, and the window fixing tube. A laser beam transmitting window attached to the outer opening end of the discharge tube, and a discharge voltage supply electrode provided at the end of the discharge tube, the inside of the discharge tube being heated by discharge. In a metal vapor laser device for generating a laser beam by generating a metal vapor in the inside of the window fixing tube, a translucent metal vapor shielding plate having a predetermined thickness, the inner surface of the laser light transmitting window Is a metal vapor laser device in which at least one sheet is installed at a predetermined interval.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. Since the structure of the main part of the metal vapor laser device is substantially the same as that of the conventional example shown in FIG. 5, the same reference numerals are used for the corresponding parts.

In the metal vapor laser device of the embodiment shown in FIGS. 1 and 2, a plurality of vapor source metals 11 are placed inside a cylindrical ceramic tube 2 which constitutes a main part of the discharge tube 1. An anode 3 and a cathode 4 are provided at both ends of the cylindrical ceramic tube 2, and a heat insulating material provided between the electrodes forming the anode 3 and the cathode 4 so as to surround the ceramic tube 2 described above. 5, an insulating tube 6 that covers the outer periphery of the heat insulating material 5, and a conductive outer cylinder 7 that supports the insulating tube 6 are provided, and a pair of window fixing tubes 8 and 9 are provided axially outward of both electrodes.
Is airtightly installed.

The outer cylinder 7 is divided into two parts at or near the center in the length direction, and is provided with a pulse shaper 22 in order to apply a predetermined operating voltage between the anode 3 and the cathode 4. The high-speed pulse power source 21 functions as voltage supply flanges 20a and 20b to which high-speed pulse high voltage can be applied.

A laser beam transmitting window 10 through which laser light enters and exits is provided at the outer opening ends of the pair of window fixing tubes 8 and 9.
a and 10b are installed obliquely and airtightly with respect to the optical axis,
Outside the windows 10a and 10b, a pair of mirrors 12 and 13 forming an optical resonator are provided.

The window fixing tube 8 connected to the anode 3 side includes
A gas supply pipe 14 for supplying, for example, neon (Ne) gas as a discharge buffer gas is connected, and a gas exhaust pipe 16 is connected to the window fixing pipe 9 connected to the cathode 4 side. The gas exhaust pipe 16 is provided with a pressure gauge 19 on the way and is connected to a vacuum exhaust pump 18 via a flow rate adjusting valve 17.

Therefore, in this metal vapor laser device, metal vapor adheres to the inner surface of each window inside the window fixing tubes 8 and 9 and in the vicinity of the laser light transmitting windows 10a and 10b. A translucent metal vapor shielding plate 24 capable of suppressing the above is installed. These metal vapor shielding plates 24 are placed slightly apart from the inner surfaces of the windows 10a and 10b obliquely attached to the optical axis and placed in parallel or substantially parallel to the inner surfaces of the windows, and the window fixing tubes 8 and 9 are provided. Is formed to have an outer diameter slightly smaller than the inner diameter thereof so that it does not contact the inner walls of the individual window fixing tubes 8 and 9 even when thermally expanded.

The metal vapor shielding plate 24 may be fixed to each of the window fixing tubes 8 and 9, but it is desirable that the metal vapor shielding plate 24 is laid down sideways by an operation from the outside of each window fixing tube, if necessary. The structure is such that it can be saved outside the main optical path of the laser light.
An example of the configuration will be described with reference to (a), (b) and (c) of FIG. (A) of the same figure is a vertical cross-sectional view of the main part, (b) of the same figure is a cross-sectional view taken along line II-II of (a), and (c) of the same figure is an enlarged vertical cross-sectional view of the main part. is there.

That is, in this example, the cross-sectional shape of the window fixing tube 8 is formed into a generally semicylindrical shape, and one piece of the shielding plate supporting member 25 made of a hinge-like metal fitting is fixed to the bottom wall portion thereof. The lower peripheral portion of the metal vapor shield plate 24 is bonded to the other arcuate piece of the support member 25.

Further, U is attached to the bottom wall portion of the window fixing tube 8.
A control rod 26 having a character shape is provided so as to penetrate therethrough.
The O-ring 27 and the seal ring 28 are movable in the vertical direction of the figure with respect to the window fixing tube 8 and are hermetically sealed. When the metal vapor shield plate 24 is held parallel to the inner surface of the window 10a, both ends of the metal vapor shield plate 24 contact the vicinity of both ends of the shield plate support member 25 with the control rod 26 positioned above. The metal vapor shielding plate 24 is held obliquely with respect to the optical axis, that is, parallel or substantially parallel to the inner surface of the window 10a.

On the other hand, when it is necessary to retract the metal vapor shield plate 24 to the outside of the main optical path of the laser after the laser device continues to operate for a predetermined time, the control rod 26 is pushed down as shown by the arrow. Thereby, the shielding plate support member 25
The other piece in the shape of an arc falls on the direction of the anode 3, and the metal vapor shield plate 24 adhered to the piece is attached to the window fixing pipe 8.
It will be in a state of lying down almost along the bottom wall part of. Thus
If necessary, the metal vapor shield plate 24 can be retracted outside the main optical path of the laser by an external operation.

By providing such a mechanism, the metal vapor shield device 24 is arranged in the vicinity of the inner surface of the window 10a at a predetermined interval, and the metal vapor laser device is provided with, for example, 10
When the metal layer is deposited on the metal vapor shielding plate 24 for a period of 00 hours and interferes with the normal continuation of the oscillating operation, the metal vapor shielding plate 24 is moved to the outside of the laser main optical path by the above operation at that time. Save. Thereby, after that, the metal vapor is directly deposited on the inner surface of the window 10a, but the normal oscillation operation can be continued until the operation of the laser device interferes with the deposition. In this way, as a whole, normal and stable operation can be continued for a considerably long time.

By the way, the metal vapor shielding plate 24 can be composed of, for example, a plate of quartz glass, magnesium fluoride, calcium fluoride, sapphire, or optical glass such as BK7.

The thickness of the metal vapor shielding plate 24 is, for example, 3 mm so as not to reduce the transmittance of laser light as much as possible.
The following is preferable, and more preferably, the thickness is 2 mm or less. However, in order to secure physical strength, approximately 1 m
It is formed with a thickness of m or more.

Next, laser oscillation will be described. In the above-mentioned metal vapor laser device, the flow rate adjusting valve 17 is operated by the signal from the pressure gauge 19, whereby the pressure of the discharge buffer gas in the discharge tube 1 is set to a predetermined pressure.

Next, the voltage supply flange 20a on the cathode 4 side
A high-speed pulse high voltage is applied from the high-speed pulse power source 21 with the pulse shaper 22 between the anode and the voltage supply flange 20b on the anode 3 side. That is, in synchronization with the pulse timing signal from the pulse shaper 22, the high-speed pulse power supply 2
1 outputs a high-speed pulse high voltage. The pulsed high voltage has a rise time of about 10 ⁻⁷ seconds or less, a peak voltage of about 100 kV, and a repetition frequency of several kHz to several tens of kHz.

In the metal vapor laser device described above, as already explained, the metal vapor evaporated from the vapor source metal 11 fills the ceramic tube 2 and also passes through the anode 3 and the cathode 4 to fix the window. The light is diffused inside the tubes 8 and 9 and further diffuses or scatters to the vicinity of the laser light transmitting windows 10a and 10b, but hardly or not adheres to the inner surfaces of the windows 10a and 10b, and before this. It adheres to a metal vapor shield plate 24.

Therefore, when the laser device is operated for a long time, the metal vapor shield plate 24 attaches the metal vapor, which has been attached to the laser beam transmitting windows 10a and 10b, to the metal vapor shield plate 24 itself. By doing so, it is possible to suppress the adhesion to the laser beam transmitting windows 10a and 10b. As a result, it is possible to prevent the laser light transmittance of the laser light transmitting windows 10a and 10b from decreasing or increasing in temperature, and suppress the occurrence or increase of the thermal lens action.

However, the laser light transmitting windows 10a, 10
When the metal vapor shielding plate 24, which is an optical glass plate, is arranged near b, as a result, the laser light transmitting windows 10a and 10 are formed.
It behaves similarly as the thickness of b increases. That is, the laser beam transmitting windows 10a and 10b have their areas (sizes).
However, a thickness of about 10 mm is required to prevent mechanical bending during flat surface polishing. Therefore,
When the thickness of the metal vapor shielding plate 24 is added, the thickness of the metal vapor shielding plate 24 must be set so that the influence on the laser oscillation operation characteristics can be substantially ignored.

The increase in the thickness of the laser light transmitting windows 10a and 10b means that the distance that the laser light transmits through the light incident transmitting window increases, and the laser light transmitting windows 10a and 10b increase.
The temperature difference between the central portion and the peripheral portion of 10b, that is, the temperature distribution is increased. As described above, when the temperature distribution of the laser light transmitting window increases, a non-uniform distribution of the refractive index occurs and the thermal lens effect increases, so that the laser light transmitting window 1
0a and 10b will be convex lenses.

FIG. 3 shows laser light transmitting windows 10a and 10b.
When the temperature difference between the central portion and the peripheral portion of the laser light is 50 ° C., the parallel laser light passing through the laser light transmitting windows 10a and 10b is converged by the convex lens of the laser light transmitting window, and the parallelism is improved. The relationship in which the degree of reduction is taken as the focal length of the lens will be described. As is clear from FIG. 3, when the thickness of the laser light transmitting window is 10 mm and the temperature difference is 50 ° C., the focal length is 200 m.
Will be reduced to. On the other hand, when the thickness of the metal vapor shielding plate 24 is 2 mm, the focal length of the metal vapor shielding plate 24 itself can be secured at about 800 m even at the same temperature difference of 50 ° C. However, the temperature difference between the central portion and the peripheral portion of the metal vapor shielding plate 24 is considered to be lower than 50 ° C. due to its structure. Therefore, even if the metal vapor is deposited on the metal vapor shield plate 24 itself, the deterioration of the parallelism of the laser light is considerably suppressed.

As described above, when the thickness of the laser beam transmitting window becomes thicker, the distance that the laser beam has to pass through the laser beam transmitting window is increased even if the temperature distribution is the same, so that it becomes a convex lens, that is, a thermal lens action. However, even if the temperature of the metal vapor shielding plate 24 rises and a refractive index distribution is generated by capturing the metal vapor with the metal vapor shielding plate 24, the focal length is reduced due to the effect of forming the convex lens. To the extent that
Compared to the case where the laser light transmitting window is formed as a convex lens, there is an advantage that it is not so remarkable.

As described above, the metal vapor shield plate 24 is
After the laser device has been operated for a predetermined time, it is tilted in the window fixing tube and removed from the main optical path of the laser light, so that the metal vapor adheres to the metal vapor shielding plate 24, thereby the laser light transmittance of the laser light transmitting window. It is possible to suppress the decrease of the temperature and the occurrence of the thermal lens effect, that is, the convex lens effect.

As described above with reference to FIG. 6, the transmittance of the laser beam of the metal vapor shield plate 24 is reduced by about 0.2% after about 1000 hours of operation. By removing the shield plate 24 from the main optical path of the laser light, it is possible to operate the laser light transmission window 10a for about 2000 hours until the laser light transmittance of the laser light transmission window 10a decreases by about 0.2%.

As described above, according to the embodiment of the present invention, since the metal vapor shielding plate for suppressing the adhesion of metal vapor to the inner surface of the laser light transmitting window is installed, the laser of the laser light transmitting window is provided. It is possible to suppress the thermal lens effect due to the decrease in light transmittance and the increase in temperature, and it is possible to stably operate the laser device for a long time.

FIG. 4 is a schematic diagram for explaining another embodiment of the present invention. The same components as those described above with reference to FIGS. 1 and 2 are designated by the same reference numerals, and detailed description thereof will be omitted. Also in FIG. 4, the window 1 for transmitting laser light is
Only the 0a side is shown, but the laser beam transmitting window 1 on the opposite side is shown.
It goes without saying that a similar mechanism may be provided for 0b.

In the metal vapor laser device shown in FIG. 4, a plurality of translucent metal vapor shielding plates are provided in the window fixing tube 8 in a region close to the laser light transmitting window 10a with a slight gap therebetween. It is provided in parallel or substantially parallel to 10a, that is, obliquely with respect to the optical axis, and can be sequentially withdrawn from the main optical path of the laser light after a lapse of a predetermined time.

More specifically, as shown in FIG.
The first to third metal vapor shielding plates 24a, 24b and 2 are provided near the laser beam transmitting window 10a in the window fixing tube 8.
4c are supported by shield plate supporting members 25a, 25b and 25c as shown in FIG. 4 (b), respectively. In addition, each of the shielding plate support members 25a, 2
5b and 25c are corresponding control rods 26 that are movable through the bottom wall of the window fixing tube 8 as shown in FIG. 4 (c).
It is supported by a, 26b and 26c. Also,
The individual control rods 26a, 26b and 26c are respectively provided with corresponding O-rings 27a, 27b and 2c.
The window fixing pipe 8 is hermetically sealed by the 7c and the seal rings 28a, 28b, 28c.

With this configuration, the metal vapor shielding plates 24a, 24b and 24c are respectively connected to the control rods 26a and 26.
By controlling the movement of b and 26c from the outside of the window fixing tube 8, it is possible to sequentially remove or withdraw from the main optical path of the laser light from the metal vapor shielding plate located far from the window 10a. It is needless to say that the metal vapor of the vapor source metal 11 diffused or scattered in the window fixing pipe 8 adheres most to the third metal vapor shielding plate 24c side closer to the ceramic pipe 2. Absent.

Thus, the plurality of metal vapor shield plates 24
By removing a, 24b, and 24c from the main optical path of the laser light in the window fixing tube 8 in order from the side closer to the ceramic tube 2 after the operation for a predetermined time, a decrease in the laser light transmittance and the occurrence of a thermal lens action are generated. Can be suppressed for a longer time.

As described above with reference to FIG. 6, the laser light transmittance is reduced by about 0.2% per sheet of metal vapor shielding plate after the operation for about 1000 hours. Bring down the metal vapor shield plate 24c,
By tilting the metal vapor shielding plates 24b and 24a in this order every 000 hours, approximately 4000 hours of operation can be performed before the laser light transmittance of the laser light transmitting window 10a decreases by about 0.2%. . Furthermore, the number of metal vapor shield plates is not limited to three, and any number can be installed.

[0046]

As described above, according to the metal vapor laser device of the present invention, the metal vapor from the vapor source metal is adhered to the inside of the laser light transmitting window at a predetermined interval. By installing at least one metal vapor shielding plate made of optical glass, it is possible to suppress a decrease in laser light transmittance and a thermal lens action due to the laser light transmitting window or the metal vapor shielding plate, and to stabilize the laser for a long time. Oscillation operation can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic view showing a metal vapor laser device of the present invention.

FIG. 2 is an enlarged cross-sectional view showing a main part of FIG.

FIG. 3 is a graph showing the relationship between the thickness of the window for transmitting laser light and the thickness of the metal vapor shielding plate and the change in parallelism of laser light.

FIG. 4 is an enlarged sectional view of an essential part showing another embodiment of the present invention.

FIG. 5 is a schematic view showing a known metal vapor laser device.

FIG. 6 is a graph illustrating changes in the amount and transmittance of metal vapor adhering to the laser light transmitting window.

FIG. 7 is a graph for explaining the temperature rise of the window due to the adhesion of metal vapor to the window for transmitting laser light.

FIG. 8 is a graph illustrating the light intensity of laser light transmitted through the laser light transmission window and the temperature difference between the central portion and the peripheral portion of the window.

FIG. 9 is a graph for explaining changes in the light intensity of laser light transmitted through the laser light transmission window and the focal length of the window.

[Explanation of symbols]

1 ... Discharge tube, 2 ... Ceramic tube, 8 ・ ・ ・ Window fixing tube, 9 ... Tubes for fixing windows, 10a, 10b ... Laser light transmitting window, 11 ... Steam source metal, 21 ・ ・ ・ High-speed pulse power supply, 22 ・ ・ ・ Pulse shaper, 24, 24a, 24b, 24c ... Metal vapor shield plate, 25, 25a, 25b, 25c ... Shielding plate support member, 26, 26a, 26b, 26c ... Control rod, 27, 27a, 27b, 27c ... O-ring, 28, 28a, 28b, 28c ... Seal ring.

Continued front page    (72) Inventor Makoto Fukuda             8 East Shinsugita-cho, Isogo-ku, Yokohama-shi, Kanagawa             Shiba Electronics Engineering Co., Ltd. F-term (reference) 5F071 AA03 DD07 FF09 JJ03 JJ05

Claims (5)

[Claims] 1. A discharge tube to which a discharge gas is supplied, a window fixing tube connected to the opening end of the discharge tube and extended outward, and attached to the opening end of the window fixing tube. A laser beam transmitting window provided, and a discharge voltage supply electrode provided at the end of the discharge tube, the discharge tube is heated by discharge to generate a metal vapor in the discharge tube to generate a laser beam. In the obtained metal vapor laser device, a translucent metal vapor shielding plate having a predetermined thickness is installed inside the window fixing tube at a predetermined distance from the inner surface of the laser light transmitting window. Metal vapor laser device characterized by. 2. The metal vapor shield plate can be retracted to a position deviated from the main optical path of the laser light.
The described metal vapor laser device. 3. The metal vapor laser device according to claim 1 or 2, wherein a plurality of the metal vapor shield plates are installed at intervals. 4. The metal vapor shield plate is positioned away from the main optical path of the laser light in order from the metal vapor shield plate located farther from the laser light transmission window according to the laser oscillation operation time of the laser device. The metal vapor laser device according to claim 2, wherein the metal vapor laser device is configured to be retractable. 5. The metal vapor shielding plate is made of quartz, magnesium fluoride, calcium fluoride, sapphire, or BK.
The metal vapor laser device according to any one of claims 1 to 4, which is a plate of optical glass such as 7.