JP2015050243A - Laser apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser apparatus capable of stably obtaining pulse laser light having controllability combined with high output, and high quality even when an optical axis position of an optical resonator is displaced to an electrode in a gas flow direction.SOLUTION: When a discharge area formed between a pair of electrodes is divided into a first discharge area, a second discharge area and a third discharge area, respectively, from the upstream side in a gas flow direction of laser gas, the discharge power density averaged in an optical axis direction of a laser beam in the second discharge area is smaller than that averaged in the optical axis direction of the laser beam in the first discharge area, and an optical axis of an optical resonator is provided so as to pass through the second discharge area.

Description

  The present invention relates to a laser device that generates laser light by using a gas as a laser medium.

  Conventionally, a laser medium (laser gas) that moves in a first direction, an optical resonator that includes an oscillation region that oscillates pulsed laser light in the laser medium, and an optical axis that extends along a second direction that intersects the first direction. An optical amplifier having an amplification region for amplifying pulsed laser light from the optical resonator in the laser medium, and a Q switch element (optical modulation element) for periodically changing the Q value of the optical resonator Is known (for example, see Patent Document 1).

JP 2012-74434 A

M.M. Kuzumoto et al., “Role of N2 gas in a transverse-flow CW CO2 laser excited by silt discharge”, J. Am. Phys. D: Appl. Phys. 22 (1989), p. 1835-1839

However, the prior art has the following problems.
The conventional laser device described in Patent Document 1 has a discharge region in which an optical resonator that oscillates pulsed laser light and an optical amplifier that amplifies the pulsed laser light are integrated. At this time, since the magnitude of the gain of the optical resonator on the upstream side of the gas flow changes depending on the position, the degree of freedom in design is low.

  Specifically, the gain of the laser excited between the electrodes forming the discharge region gradually increases from the upstream end of the gas flow along the direction in which the laser gas flows, and is greatest at the downstream end of the gas flow of the electrode. It is distributed with a gradient so that it gradually decreases. That is, the optical axis of the optical resonator disclosed in Patent Document 1 exists in a region having a gradient in gain distribution.

  In such a case, when the optical axis of the optical resonator changes in the gas flow direction, the magnitude of the gain at the optical axis position also changes, and the light intensity of the laser light in the optical resonator also changes. At this time, for example, even if the optical axis position of the optical resonator is changed by 1 mm, the optical intensity in the optical resonator (hereinafter referred to as “intracavity light intensity”) may change by several tens of percent.

In addition, an optical modulator is attached to the optical resonator, thereby taking out a laser pulse by applying pulse modulation. Here, the light modulation element is, for example, an acousto-optic element using germanium as a material, and the light modulation element may be destroyed when high-intensity light is incident. For example, in an acoustooptic device using general germanium, it is necessary to set it to 3 kW / cm ² or less.

  On the other hand, in order to extract a laser pulse with good controllability and quick rise, the higher the light intensity in the resonator, the better. Therefore, the optical axis position of the optical resonator must be accurately determined at a position where a high light intensity is obtained to such an extent that the optical modulation element is not destroyed.

  However, an error of about 1 to 2 mm exists in the optical axis position of the optical resonator due to the influence of the electrode installation accuracy and the like. Therefore, conventionally, the optical axis of the optical resonator is positioned at a position where the gain is small and the light intensity is not so high in consideration of the effect of error when the optical axis position of the optical resonator is shifted in the gas flow direction with respect to the electrode. Is provided.

  For this reason, the conventional laser apparatus has a problem that high-power pulse laser light, that is, high light intensity in the resonator, high controllability, and high-quality pulse laser light cannot be obtained stably.

  The present invention has been made to solve the above-described problems. Even when the optical axis position of the optical resonator is shifted in the gas flow direction with respect to the electrode, high output and controllability are achieved. The object is to obtain a laser device that can stably obtain high-quality pulsed laser light.

  A laser apparatus according to the present invention is a laser apparatus that generates laser light by using a laser gas as a medium, and in which the gas flow direction of the laser gas and the optical axis direction of the laser light in the laser gas intersect, A pair of electrodes to be excited, a discharge region that is formed between the pair of electrodes, an optical resonator that oscillates laser light, and a discharge region that is formed between the pair of electrodes. And an optical amplifier that amplifies the laser beam, and the discharge region formed between the pair of electrodes is divided into a first discharge region, a second discharge region, and a third discharge region from the upstream side in the gas flow direction of the laser gas, respectively. In this case, the discharge power density averaged in the optical axis direction of the laser light in the second discharge region is the discharge power density averaged in the optical axis direction of the laser light in the first discharge region. Remote small, the optical axis of the optical resonator, in which are provided so as to pass through a second discharge region.

According to the laser apparatus of the present invention, the discharge region formed between the pair of electrodes is divided into the first discharge region, the second discharge region, and the third discharge region from the upstream side in the gas flow direction of the laser gas, respectively. Furthermore, in the second discharge region, the discharge power density averaged in the optical axis direction of the laser beam is smaller than the discharge power density averaged in the optical axis direction of the laser beam in the first discharge region, and the optical resonance The optical axis of the vessel is provided to pass through the second discharge region.
Thereby, the gain distribution in the optical resonator portion can be made uniform.
Therefore, even when the optical axis position of the optical resonator is shifted in the gas flow direction with respect to the electrode, high output, good controllability, and high-quality pulsed laser light can be stably obtained.

It is an explanatory view showing a discharge power density distribution of the gas flow direction in the general three-axis orthogonal type CO ₂ laser apparatus. It is an explanatory diagram showing a gain distribution of the gas flow direction in the general three-axis orthogonal type CO ₂ laser apparatus. It is an explanatory diagram showing the relationship between the position of the optical axis of the optical resonator and resonator light intensity in the general three-axis orthogonal the CO ₂ laser device. It is a block diagram which shows the laser apparatus concerning Embodiment 1 of this invention. It is the top view which looked at the laser apparatus concerning Embodiment 1 of this invention from the upper part. It is sectional drawing which shows the structure of the discharge mechanism of the laser apparatus concerning Embodiment 1 of this invention. It is sectional drawing which shows the structure of the discharge mechanism of the laser apparatus concerning Embodiment 1 of this invention. It is explanatory drawing which shows the discharge power density distribution of the gas flow direction in the laser apparatus concerning Embodiment 1 of this invention. It is explanatory drawing which shows the gain distribution of the gas flow direction in the laser apparatus concerning Embodiment 1 of this invention. It is the top view which looked at the laser apparatus concerning Embodiment 2 of this invention from the upper part. It is sectional drawing which shows the structure of the discharge mechanism of the laser apparatus concerning Embodiment 2 of this invention. It is the top view which looked at the laser apparatus concerning Embodiment 3 of this invention from the upper part. It is sectional drawing which shows the structure of the discharge mechanism of the laser apparatus concerning Embodiment 3 of this invention. It is the top view which looked at the laser apparatus concerning Embodiment 4 of this invention from the upper part. It is the top view which looked at the laser apparatus concerning Embodiment 5 of this invention from the upper part. It is the top view which looked at the laser apparatus concerning Embodiment 5 of this invention from the upper part.

  Hereinafter, preferred embodiments of the laser apparatus according to the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts will be described with the same reference numerals.

First, with reference to Patent Document 1 and Non-Patent Document 1, laser gain distribution and intracavity light intensity in a general three-axis orthogonal CO ₂ laser device will be described in detail. For example, the gain distribution of the laser pumped between the electrodes of the three-axis orthogonal CO ₂ laser apparatus as shown in FIG. 1 of Patent Document 1 is shown in FIG. As shown in

FIG. 1 of Non-Patent Document 1. FIG. 6 is a diagram showing the relationship between gain distribution and electrode position in a triaxial orthogonal CO ₂ laser device, and the gain gradually increases from the gas flow upstream end of the electrode along the direction in which the laser gas flows. It can be seen that the gain gradually decreases after the gain becomes maximum at the downstream end of the gas flow.

Here, the function g ₀ (X) of the laser gain distribution is expressed by the following equation (1). Note that in the following equation (1), X is the gas flow direction of the coordinates, X _D is the electrode width, lambda is the relaxation rate of the laser high level, upsilon the laser gas flow rate, sigma is stimulated emission cross section, eta excitation efficiency, w represents the discharge power density, and V represents the discharge voltage.

1 and 2 show the discharge power density distribution and the gain distribution between the electrodes of the three-axis orthogonal CO ₂ laser apparatus as disclosed in Patent Document 1, respectively. 1 and 2, the horizontal axis indicates the distance from the gas flow upstream end of the electrode in the gas flow direction, and the gas flow upstream end of the electrode is zero. Further, the vertical axis in FIG. 1 shows the discharge power density distribution when the electrode width in the gas flow direction is 40 mm, and the vertical axis in FIG. 2 shows the gain distribution at this time.

  That is, when the discharge power density is uniformly distributed in the gas flow direction, FIG. 2 or FIG. It can be seen that the gain distribution has a gradient in the gas flow direction. Therefore, as described above, the optical axis of the optical resonator disclosed in Patent Document 1 exists in a region having a gradient in the gain distribution.

FIG. 3 shows the relationship between the optical axis position and the light intensity in the resonator when the optical axis position of the optical resonator changes in the triaxial orthogonal CO ₂ laser device disclosed in Patent Document 1. . In FIG. 3, the horizontal axis indicates the distance from the gas flow upstream end of the electrode to the optical axis position, and the vertical axis indicates the light intensity in the resonator.

  From FIG. 3, for example, when the optical axis of the optical resonator is installed at a position 15 mm from the gas flow upstream end of the electrode, the optical intensity in the resonator is about 30% even if the optical axis position is changed by 1 mm. You can see that it changes.

Embodiment 1 FIG.
FIG. 4 is a block diagram showing the laser apparatus according to Embodiment 1 of the present invention. FIG. 5 is a plan view of the laser apparatus according to Embodiment 1 of the present invention as viewed from above. 4 and 5, this laser device is provided in an optical resonator having electrode substrates 1, 2, 3, 4, electrodes 5, 6, a laser gas G, mirrors 21 and 22, and an optical resonator. The optical modulation element 26, transmission mirrors 51 and 52, and an optical amplifier including mirrors 53, 54, 55, and 56. In FIG. 5, the upper electrode substrate 1 and the electrode 5 are omitted.

  Here, in order to avoid the complexity of the drawings, the electrode substrates 3 and 4 are not shown in FIGS. 4 and 5, and will be described later with FIGS. 6 and 7 (cross-sectional views showing the configuration of the discharge mechanism of the laser device). 2 shows the electrode substrates 3 and 4. For easy understanding, the direction parallel to the direction in which the laser gas G is supplied is defined as the X direction, the direction of discharge for exciting the laser gas G is defined as the Y direction, and the optical axis direction of the optical resonator and the optical amplifier is defined as the Z direction.

  6 is a cross-sectional view showing the configuration of the discharge mechanism of the laser apparatus according to Embodiment 1 of the present invention. In FIG. 5, the cross section of the laser apparatus cut along the line AA is shown in the optical axis direction (Z direction). ).

  In FIG. 6, the electrode substrate 3 is made of a dielectric material such as alumina, and the metal electrode 5 is bonded by metallization, paste, or the like. The electrode substrate 1 is formed of a dielectric material such as alumina, and is bonded to the electrode substrate 3 in order to make the mechanical strength of the entire discharge mechanism sufficient.

  Similarly, the electrode substrate 4 is formed of a dielectric material such as alumina, and a metal electrode 6 is bonded by metallization, paste, or the like. The electrode substrate 2 is made of a dielectric material such as alumina, and is bonded to the electrode substrate 4 in order to make the mechanical strength of the entire discharge mechanism sufficient.

  7 is a cross-sectional view showing the configuration of the discharge mechanism of the laser device according to Embodiment 1 of the present invention, similar to FIG. 6. In FIG. 5, the cross section of the laser device cut along the line BB in FIG. It is the figure seen from the direction (Z direction).

  7 is different from FIG. 6 in that the electrodes 5 and 6 are separated on the upstream side and the downstream side in the gas flow direction (X direction). However, as shown in FIG. 5, since the electrodes 5 and 6 are connected at the AA line portion, they are integrated as a whole, and have the same potential on the upstream side and the downstream side.

  As shown in FIGS. 6 and 7, the two electrode substrates 1 and 2 configured as described above are disposed to face each other with the laser gas G interposed therebetween, and are connected to the electrodes 5 and 6 from a high-frequency power source (not shown). When an alternating voltage is applied, silent discharge (ozonizer discharge) occurs between the electrodes.

  Hereinafter, the discharge region formed between the pair of electrodes 5 and 6 is divided into the first discharge region 11 and the second discharge from the upstream side in the gas flow direction (X direction) as shown in FIGS. A description will be given by dividing into three regions, region 12 and third discharge region 13. Here, the width of the first discharge region 11 in the gas flow direction is Xs.

When molecules or atoms in the laser gas G are excited to a laser upper level by silent discharge, the light amplification effect is exhibited. For example, when a mixed gas containing CO ₂ molecules is used as the laser gas G, laser oscillation light having a wavelength of 10.6 μm is obtained due to the transition between vibration levels of the CO ₂ molecules. Further, depending on the design of the reflective films of the mirrors 21 and 22, oscillation at other wavelengths such as a wavelength of 9.3 μm is possible.

Here, the case where CO ₂ is used as the laser gas G is illustrated, but other laser gases such as CO, N ₂ , He—Cd, HF, Ar +, ArF, KrF, XeCl, XeF, etc. are used. In addition, the present invention is applicable.

  The laser apparatus according to Embodiment 1 of the present invention includes a housing (not shown) that is a vacuum container for blocking the laser gas G from the outside air, and a heat exchanger, a blower, a duct, and the like are provided inside the housing. Is provided. The blower circulates the laser gas G sealed in the casing along the wind tunnel in the duct. Accordingly, the laser gas G is supplied along the X direction in the order of the first discharge region 11 → the second discharge region 12 → the third discharge region 13.

  The laser gas G that has passed through the first to third discharge regions 11, 12, and 13 is cooled by the heat exchanger and returns to the blower again. In the first to third discharge regions 11, 12, and 13, the pressure is maintained lower than the atmospheric pressure, and the laser gas G has a spatially uniform velocity distribution in the direction of the arrow in FIG. 4, for example, 90 m / s. Move at a moderate speed.

  The mirrors 21 and 22 are disposed so as to face each other with the second discharge region 12 interposed therebetween. As the mirror 21, for example, a concave or flat total reflection mirror is used. As the mirror 22, for example, a concave or flat partial reflection mirror is used, and the two mirrors 21 and 22 constitute an optical resonator. .

  The optical resonator has an optical axis along a direction that intersects the moving direction (X direction) of the laser gas G, preferably in the orthogonal Z direction. An aperture (not shown) for controlling the beam mode of the laser beam is provided on the optical axis of the optical resonator.

  The light modulation element 26 has a function of controlling the polarization, propagation direction, transmittance, and the like of transmitted light at high speed. The light modulation element 26 also has a function of controlling the Q value of the optical resonator at high speed, and can generate pulsed laser light B0 having a pulse width of several tens to several hundreds ns from the optical resonator.

  Here, as the light modulation element 26, an acousto-optic element, an electro-optic element, a mechanical shutter, a chopper, or the like can be used. When an acousto-optic element is used as the light modulation element 26, a drive circuit (not shown) for supplying an AC voltage of several tens of MHz is connected.

  The transmission mirrors 51 and 52 function as folding mirrors that allow the laser beam B0 from the optical resonator to enter the third discharge region 13 that is an optical amplifier as the laser beam B1. In the first embodiment of the present invention, a convex total reflection mirror is used as the transmission mirror 51, and a concave total reflection mirror is used as the transmission mirror 52 to constitute a beam expander that expands the beam diameter of the laser light.

  Specifically, in the first embodiment of the present invention, the laser beam B0 having a beam radius of about 3 mm is reincident on the third discharge region 13 on the mirror 22 by the action of the transmission mirrors 51 and 52. Immediately before, the beam diameter is expanded and collimated so that the laser beam B1 has a beam radius of about 5 mm.

  With such a configuration, in the first embodiment of the present invention, in the optical resonator having the mirrors 21 and 22, the beam diameter of the laser light is reduced to ensure low-order transverse mode oscillation with good beam quality, In an optical amplifier, the beam diameter is increased to improve the amplification efficiency of laser light.

  The mirrors 53, 54, 55, and 56 are arranged so as to sandwich the third discharge region 13, and constitute an optical amplifier. The laser beam B1 turned back by the transmission mirrors 51 and 52 is transmitted from the transmission mirror 52 → the third discharge region 13 → the mirror 53 → the third discharge region 13 → the mirror 54 → the third discharge region 13 → the mirror 55 → the third discharge region 13. When traveling in the order of the mirror 56 → the third discharge region 13, it is amplified by the excited laser gas G.

  In Embodiment 1 of the present invention, the laser beam B1 turned back by the transmission mirrors 51 and 52 is amplified by passing through the third discharge region 13 five times, and finally the laser beam B2 having an average output of 1 kW is extracted. It is.

  The third discharge region 13 that is an optical amplifier has a plurality of (three in the example in Embodiment 1 of the present invention) along the direction that intersects the moving direction (X direction) of the laser gas G, and preferably in the orthogonal Z direction. With a folded optical axis. By arranging these folded optical axes along the Y direction, the gain of the laser gas G received by each optical axis is equalized, and as a result, a stable amplification operation can be realized.

  The mirrors 21 and 22, the transmission mirrors 51 and 52, and the mirrors 53, 54, 55, and 56 are attached to a housing or the like via an angle fine adjustment mechanism for optical axis adjustment.

  Here, the discharge power density distribution and the gain distribution between the electrodes of the laser apparatus according to Embodiment 1 of the present invention are shown in FIGS. 8 and 9, the horizontal axis indicates the distance from the gas flow upstream end of the electrode in the gas flow direction (X direction), and the gas flow upstream end of the electrode is zero. Further, the vertical axis in FIG. 8 shows the discharge power density distribution when the electrode width in the gas flow direction is 40 mm, and the vertical axis in FIG. 9 shows the gain distribution at this time.

  8 and 9, the discharge power density distribution and the gain distribution show values integrated (averaged in the optical axis direction) over the entire electrode in the optical axis direction (Z direction). With the electrode structure of the laser device according to Embodiment 1 of the present invention, the discharge power density distribution includes a portion with a small discharge power, as shown in FIG.

  This is because the electrodes 5 and 6 are arranged in the optical axis direction (Z direction) in the second discharge region 12 as shown in the AA line part, BB line part and FIGS. This is because of having an electrode pattern in which the discharge portion and the non-discharge portion are alternately repeated.

  That is, the second discharge region 12 is not discharged over the entire optical axis direction, but only a part is discharged, while in the first and third discharge regions 11 and 13, the optical axis is discharged. This is because the discharge is performed in the entire direction. Further, the gain distribution at this time is uniform in the gas flow direction in the second discharge region 12.

  The gain distribution is uniform by adjusting the relaxation rate λ of the laser upper level, the laser gas flow velocity υ, and the ratio of the second discharge region 12 to the first and third discharge regions 11 and 13 in the above formula (1). It becomes possible to.

  Further, the laser upper level relaxation rate λ is mainly determined by the laser gas composition and the gas pressure. In FIG. 8, when the laser gas flow velocity υ is 90 m / s, the discharge power averaged over the optical axis direction (Z direction) of the second discharge region 12 is expressed as the first and third discharge regions 11, 13 shows a case where the ratio is about 17%. In other words, by appropriately adjusting these parameters, it is possible to create a region where the gain distribution is constant.

  Here, the ratio Dr of the average discharge power density of the second discharge region 12 with respect to the first and third discharge regions 11 and 13 may be determined as in the following equation (2).

    Dr = 1−exp (−λ · Xs / υ) (2)

In a typical CO ₂ laser, the laser upper level relaxation rate λ operates at about 500 to 4000 per second depending on the laser gas composition and gas pressure. Therefore, first, the laser gas composition and gas pressure are determined, and the width Xs of the first discharge region 11 in the gas flow direction (X direction) and the ratio Dr of the discharge power density of the second discharge region 12 are determined according to these values. do it.

  By doing so, even when the optical axis position of the optical resonator is shifted by about 1 to 2 mm in the gas flow direction with respect to the electrode, a constant gain is always obtained, and the mirror alignment error can be obtained. In addition, it is possible to suppress a change in the light intensity in the resonator.

  As a result, it is possible to improve the design freedom of each optical component in consideration of the light resistance strength of the optical component with respect to the power of the laser beam generated in the optical resonator, the optical power amplification capability of the optical component in the optical amplifier, etc. it can.

  Further, in the laser device according to the first embodiment of the present invention, the laser beam B0 having a good beam quality is generated by the optical resonator and the laser beam is amplified, as in the conventional laser device. A good high power beam can be obtained. Further, by providing the optical resonator and the optical amplifier in the same housing (vacuum vessel), a laser apparatus that is inexpensive and easy to assemble and install can be obtained.

  Furthermore, the laser apparatus according to Embodiment 1 of the present invention has a configuration in which a metal electrode is bonded to one dielectric electrode substrate by metallization, paste, or the like. Therefore, in order to generate one discharge region, it is not necessary to prepare an electrode substrate and an electrode structure one by one, and a plurality of discharge regions can be generated with an inexpensive and highly reliable configuration.

As described above, according to the first embodiment, the discharge region formed between the pair of electrodes is changed from the upstream side in the gas flow direction of the laser gas to the first discharge region, the second discharge region, and the third discharge region, respectively. When divided, the discharge power density averaged in the optical axis direction of the laser light in the second discharge region is smaller than the discharge power density averaged in the optical axis direction of the laser light in the first discharge region. The optical axis of the optical resonator passes through the second discharge region.
Thereby, the gain distribution in the optical resonator portion can be made uniform.
Therefore, even when the optical axis position of the optical resonator is shifted in the gas flow direction with respect to the electrode, high output, good controllability, and high-quality pulsed laser light can be stably obtained.

Embodiment 2. FIG.
In the first embodiment, the ratio of the discharge power of the second discharge region 12 with respect to the first and third discharge regions 11 and 13 is obtained by thinning out the actual discharge region in the second discharge region 12 of the electrodes 5 and 6. It was adjusted by.

  In the second embodiment of the present invention, the ratio of the discharge power of the second discharge region 12 to the first and third discharge regions 11 and 13 is adjusted by increasing the thickness of the dielectric of the second discharge region 12. explain.

  FIG. 10 is a plan view of the laser device according to the second embodiment of the present invention as viewed from above, and the upper electrode substrate 1 and the electrode 5 are omitted as in FIG. 5 of the first embodiment. Yes. Further, the portions through which the laser beam passes, such as a mirror and a light modulation element, are the same as those in the first embodiment, and a description thereof will be omitted.

  FIG. 11 is a cross-sectional view showing the configuration of the discharge mechanism of the laser apparatus according to Embodiment 2 of the present invention. In FIG. 10, the cross section of the electrode portion of the laser apparatus cut in the gas flow direction (X direction). It is the figure which looked at from the optical axis direction (Z direction).

  10 and 11, dielectrics 7 and 8 are bonded onto the electrode substrates 3 and 4 in the second discharge region 12. Here, the material of the dielectrics 7 and 8 can be the same as that of the electrode substrates 3 and 4.

  By doing in this way, the electrostatic capacitance of the electrode of the 2nd discharge region 12 can be made smaller than the electrostatic capacitance of the electrode of the 1st, 3rd discharge region 11 and 13. FIG. In addition, since the discharge power density is proportional to the capacitance of the electrode in the discharge portion, the discharge power density in the second discharge region 12 is reduced, and as a result, the same effect as in the first embodiment can be obtained. it can.

  That is, the gain distribution in the optical resonator portion can be made uniform, and even when the optical axis position of the optical resonator is shifted by about 1 to 2 mm in the gas flow direction with respect to the electrode, a constant gain is always obtained. As a result, a change in the light intensity in the resonator can be suppressed even with respect to the alignment error of the mirror.

  In the second embodiment, the dielectrics 7 and 8 are newly bonded onto the electrode substrates 3 and 4. However, the present invention is not limited to this, and the electrode substrate 3 and the dielectric 7, and the electrode substrate 4 and the dielectric are not limited thereto. The body 8 may be composed of an integrated ceramic or the like having steps. In this case, the same effect as that of the second embodiment can be obtained.

Embodiment 3 FIG.
In the second embodiment, the configuration in which the discharge power density in the second discharge region 12 is reduced by bonding the dielectrics 7 and 8 on the electrode substrates 3 and 4 in the second discharge region 12 has been described. However, the present invention is not limited to this, and the discharge power density of the second discharge region 12 can be reduced by devising the arrangement of the metal electrodes.

  FIG. 12 is a plan view of the laser device according to the third embodiment of the present invention as viewed from above, and the upper electrode substrate 1 and the electrode 5 are omitted as in FIG. 5 of the first embodiment. Yes. Further, the portions through which the laser beam passes, such as a mirror and a light modulation element, are the same as those in the first embodiment, and a description thereof will be omitted.

  13 is a cross-sectional view showing the configuration of the discharge mechanism of the laser device according to Embodiment 3 of the present invention. In FIG. 12, the cross section of the electrode portion of the laser device cut in the gas flow direction (X direction). It is the figure which looked at from the optical axis direction (Z direction).

  12 and 13, metal electrodes 9 and 10 are disposed on the opposite side of the electrode substrates 1 and 2 from the second discharge region 12, respectively. In addition, the electrode 9 is electrically connected to the electrode 5, and the electrode 10 is electrically connected to the electrode 6 and has the same potential.

  Here, since the electrode substrates 1 and 2 are dielectrics like the electrode substrates 3 and 4, the capacitance of the electrodes in the second discharge region 12 is made to be the same as that of the first and third discharge regions 11. , 13 can be made smaller than the capacitance of the electrodes. As a result, the discharge power density in the second discharge region 12 can be reduced, and the same effect as in the first embodiment can be obtained.

  That is, the gain distribution in the optical resonator portion can be made uniform, and even when the optical axis position of the optical resonator is shifted by about 1 to 2 mm in the gas flow direction with respect to the electrode, a constant gain is always obtained. As a result, a change in the light intensity in the resonator can be suppressed even with respect to the alignment error of the mirror.

Embodiment 4 FIG.
In order to adjust the ratio of the discharge power of the second discharge region 12 to the first and third discharge regions 11, 13, the configurations described in the first to third embodiments may be combined.

  That is, in the second discharge region 12 shown in the first embodiment, the electrode patterns of the electrodes 5 and 6 that alternately repeat the discharge portion and the non-discharge portion in the optical axis direction (Z direction), The adhesion of the dielectrics 7 and 8 to the electrode substrates 3 and 4 shown in the second embodiment and the arrangement of the electrodes 9 and 10 on the electrode substrates 1 and 2 shown in the third embodiment are selected. For example, the laser device may be configured as shown in FIG.

  Also in this case, the discharge power density of the second discharge region 12 can be reduced, and the same effect as in the first embodiment can be obtained. That is, the gain distribution in the optical resonator portion can be made uniform, and even when the optical axis position of the optical resonator is shifted by about 1 to 2 mm in the gas flow direction with respect to the electrode, a constant gain is always obtained. As a result, a change in the light intensity in the resonator can be suppressed even with respect to the alignment error of the mirror.

Embodiment 5 FIG.
In the first embodiment, the electrodes 5 and 6 have a simple electrode pattern in which the discharge portion and the non-discharge portion are alternately repeated in the optical axis direction (Z direction) in the second discharge region 12. However, the present invention is not limited to this, and may have any shape as long as the area of the electrode portion of the second discharge region 12 is smaller than the area of the electrode portion of the first and third discharge regions 11 and 13. .

  Specifically, for example, as shown in FIG. 15, the electrode portion of the second discharge region 12 may have an oblique electrode pattern, or as shown in FIG. 16, the second discharge region 12 The electrode portion may have a mesh electrode pattern.

  Also in this case, the discharge power density of the second discharge region 12 can be reduced, and the same effect as in the first embodiment can be obtained. That is, the gain distribution in the optical resonator portion can be made uniform, and even when the optical axis position of the optical resonator is shifted by about 1 to 2 mm in the gas flow direction with respect to the electrode, a constant gain is always obtained. As a result, a change in the light intensity in the resonator can be suppressed even with respect to the alignment error of the mirror.

  1-4 electrode substrate, 5-6 electrode, 7, 8 dielectric, 9, 10 electrode, 11 first discharge region, 12 second discharge region, 13 third discharge region, 21, 22 mirror, 26 light modulation element, B0, B1, B2 Laser light, 51, 52 Transmission mirror, 53-56 mirror, G Laser gas.

Claims (5)

A laser device that generates laser light by using a laser gas as a medium, and that a gas flow direction of the laser gas intersects an optical axis direction of the laser light in the laser gas,
A pair of electrodes for exciting the laser gas;
An optical resonator disposed in a discharge region formed between the pair of electrodes and oscillating the laser beam;
An optical amplifier disposed in a discharge region formed between the pair of electrodes and amplifying the laser light from the optical resonator,
When the discharge region formed between the pair of electrodes is divided into a first discharge region, a second discharge region, and a third discharge region from the upstream side in the gas flow direction of the laser gas, respectively, in the second discharge region The discharge power density averaged in the optical axis direction of the laser light is smaller than the discharge power density averaged in the optical axis direction of the laser light in the first discharge region, and the light of the optical resonator A laser device, wherein an axis passes through the second discharge region. The laser device according to claim 1, wherein the second discharge region has a uniform gain distribution in a gas flow direction of the laser gas. The ratio Dr of the average discharge power density of the second discharge region to the first discharge region is:
Dr = 1−exp (−λ · Xs / υ)
3. λ is a laser upper level relaxation rate in the laser gas, Xs is a width in the gas flow direction of the laser gas in the first discharge region, and υ is a flow velocity of the laser gas. The laser device described in 1. The laser device according to any one of claims 1 to 3, wherein the second discharge region alternately repeats a discharge portion and a non-discharge portion in the optical axis direction of the optical resonator. The thickness of the dielectric on the discharge region side for the pair of electrodes in the second discharge region is larger than the thickness of the dielectric on the discharge region side for the pair of electrodes in the first discharge region. The laser device according to any one of claims 1 to 4.

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