TWI781658B - Aperture and Laser Oscillators - Google Patents

Abstract

[Problem] To provide an aperture for an optical resonator capable of suppressing deformation of a beam profile from a perfect circle. [Solution] Arrange an aperture in the path of the laser beam closed to the optical resonator. The aperture divides a passage area through which the laser beam closed to the optical resonator passes, and a light-shielding area arranged around the passage area. The aspect ratio, which is the ratio of the sizes of the pass regions in two directions orthogonal to each other in a plane orthogonal to the optical axis of the optical resonator, is variable.

Description

Aperture and Laser Oscillator

The present invention relates to an aperture arranged in an optical resonator and a laser oscillator equipped with the aperture. This application claims priority based on Japanese Patent Application No. 2020-119131 filed on July 10, 2020. The entire content of this Japanese application is incorporated by reference in this specification.

The laser oscillator includes an optical resonator composed of a front lens and a rear lens, and an excitation mechanism such as a discharge electrode. Usually, a front aperture, a rear aperture, or both are arranged on the optical axis of the optical resonator. By configuring the aperture, the beam profile can be shaped into a perfect circle, and the beam divergence angle and parasitic oscillation can be suppressed. In order to output a laser beam with a circular beam profile, a metal plate provided with a perfect circular opening is used as an aperture (see, for example, Patent Document 1 below). [Prior Art Literature]

[Patent Document 1] Japanese Patent Application Laid-Open No. 61-276387

[Problem to be solved by the invention]

Even if the beam profile is shaped by using an aperture having a perfect circular opening, the shape of the beam profile of the laser beam output from the laser oscillator may collapse from a perfect circle to an elliptical shape.

An object of the present invention is to provide an aperture capable of suppressing the collapse of a beam profile from a perfect circle. Another object of the present invention is to provide a laser oscillator capable of suppressing the deformation of the beam profile from a perfect circle. [Technical means to solve the problem]

According to an aspect of the present invention, there is provided an aperture, which is arranged on the path of a laser beam enclosed in an optical resonator, The aforementioned aperture is divided into: the passing area through which the laser beam enclosed in the aforementioned optical resonator passes; and the light-shielding area arranged around the aforementioned passing area, and in a plane perpendicular to the optical axis of the aforementioned optical resonator, as each other The aspect ratio of the ratio of the dimensions of the aforementioned passing regions in the two orthogonal directions is variable.

According to another aspect of the present invention, a laser oscillator is provided, which has: an optical resonator that encloses a laser beam; and The aperture, which is divided into: the passing area through which the laser beam enclosed in the aforementioned optical resonator passes; and the light-shielding area arranged around the aforementioned passing area, and in a plane perpendicular to the optical axis of the aforementioned optical resonator, as the aspect ratio of the ratio of the dimensions of the aforesaid passing areas in two directions orthogonal to each other is variable; and a chamber containing the aforementioned optical resonator, the aforementioned aperture, and the laser medium gas; and The aspect ratio changing mechanism changes the aspect ratio of the passing area of the aperture by operating from outside the chamber. [Effect of Invention]

By changing the aspect ratio of the passing area of the aperture, it is possible to adjust the shape of the beam profile and suppress distortion from a perfect circle.

Referring to FIGS. 1 to 6 , a laser oscillator according to an embodiment will be described. FIG. 1 is a schematic diagram of a laser processing apparatus equipped with a laser oscillator according to this embodiment. The laser processing device includes a laser oscillator 12 and a processing device 80 .

The laser oscillator 12 is supported on a stand 11 , and the stand 11 is fixed on a common base 100 . The processing device 80 includes a beam shaping optical system 81 and a workbench 82 . The object to be processed 90 is held on the table 82 . The beam shaping optical system 81 and the table 82 are fixed on the common base 100 . The beam profiler 50 can be arranged on the path of the laser beam between the laser oscillator 12 and the beam shaping optical system 81 . During laser processing, the beam profiler 50 is withdrawn from the path of the laser beam. The common base 100 is, for example, a floor.

The laser oscillator 12 outputs a pulsed laser beam. As the laser oscillator 12, for example, a carbon dioxide laser oscillator is used. In addition, as the laser oscillator 12 , other gas laser oscillators, such as excimer laser oscillators, can also be used. The pulsed laser beam output from the laser oscillator 12 is incident on the object 90 after the beam profile is shaped by the beam shaping optical system 81 .

FIG. 2 is a cross-sectional view including an optical axis of the laser oscillator 12 according to the embodiment. The laser oscillator 12 includes a chamber 15 containing a laser medium gas, an optical resonator 20 and the like. The inner space of the chamber 15 is divided into an optical chamber 16 located on the relatively upper side and a blower chamber 17 located on the relatively lower side. The optical chamber 16 and the blower chamber 17 are separated by an upper and lower partition plate 18 . In addition, an opening through which laser medium gas flows between the optical chamber 16 and the blower chamber 17 is provided in the upper and lower partition plates 18 . The bottom plate 19 of the optical chamber 16 protrudes from the side wall of the blower chamber 17 in the direction of the optical axis 20A of the optical resonator 20 , and the length of the optical chamber 16 in the direction of the optical axis is longer than the length of the blower chamber 17 in the direction of the optical axis.

The bottom plate 19 of the chamber 15 is supported on the stand 11 ( FIG. 1 ) by means of four support points 45 . The four support portions 45 are arranged at positions corresponding to the four vertices of the rectangle in plan view.

A pair of discharge electrodes 21 and a pair of resonator mirrors 25 are arranged in the optical chamber 16 . The pair of discharge electrodes 21 are respectively fixed to the electrode case 22 . A pair of electrode boxes 22 are supported on the bottom plate 19 via a plurality of electrode support members 23 . A pair of discharge electrode 21 is arrange|positioned at intervals in the up-down direction, and the discharge region 24 is divided between them. The discharge electrode 21 generates a discharge in the discharge region 24, thereby exciting the laser medium gas. A pair of resonator mirror plates 25 constitutes an optical resonator 20 having an optical axis 20A passing through the discharge region 24 . As will be described later with reference to FIG. 3 , the laser medium gas flows through the discharge region 24 in a direction perpendicular to the paper surface of FIG. 2 .

A pair of resonator mirrors 25 are fixed on a common resonator base 26 arranged in the optical chamber 16 . The resonator base 26 is a plate-shaped member long in the direction of the optical axis 20A, and is supported by the base plate 19 via a plurality of optical resonator support members 27 .

The light generated in the discharge region 24 is repeatedly reflected between the pair of resonator mirrors 25, and a standing wave having a wavelength corresponding to the optical path length between the pair of resonator mirrors 25 is generated in the region 20B between the pair of resonator mirrors 25. . In this way, the laser beam is enclosed in the region 20B between the pair of resonator mirrors 25 . Part of the laser beam enclosed in the optical resonator 20 passes through one of the resonator mirrors 25 (the left resonator mirror 25 in FIG. 2 ) and is output to the outside. Two apertures 60 and 70 are arranged on the path of the laser beam enclosed in the optical resonator 20 . The apertures 60 and 70 are supported by the resonator base 26. The two apertures 60 and 70 are arranged at positions sandwiching the discharge region 24 in the direction of the optical axis 20A.

A translucent window 28 through which the laser beam passes is mounted at the intersection of an extension line extending in one direction (left direction in FIG. 1 ) from the optical axis 20A of the optical resonator 20 and the wall surface of the optical chamber 16 . The laser beam excited in the optical resonator 20 is emitted to the outside through the light transmission window 28 . Sometimes the aperture 60 arranged on the side of the light transmission window 28 is called a front aperture, and the other aperture 70 is called a rear aperture.

A blower 29 is arranged in the blower chamber 17 . The blower 29 circulates the laser medium gas between the optical chamber 16 and the blower chamber 17 .

FIG. 3 is a cross-sectional view perpendicular to the optical axis 20A ( FIG. 2 ) of the laser oscillator 12 according to the embodiment. As described with reference to FIG. 2 , the inner space of the chamber 15 is divided into an upper optical chamber 16 and a lower blower chamber 17 by the upper and lower partition plates 18 . A pair of discharge electrodes 21 and a resonator base 26 are arranged in the optical chamber 16 . The pair of discharge electrodes 21 are respectively fixed to the electrode case 22 . The electrode box 22 is supported on the bottom plate 19 of the chamber 15 by a plurality of electrode support members 23 ( FIG. 2 ). A discharge region 24 is defined between a pair of discharge electrodes 21 . The resonator base 26 is supported on the bottom plate 19 of the chamber 15 by a plurality of optical resonator support members 27 ( FIG. 2 ). Since the electrode supporting member 23 and the optical resonator supporting member 27 are disposed at positions shifted from the cross section shown in FIG. 3 , the electrode supporting member 23 and the optical resonator supporting member 27 are indicated by dotted lines in FIG. 3 .

A partition plate 40 is arranged in the optical chamber 16 . The partition plate 40 divides the first gas flow path 41 from the opening 18A provided in the upper and lower partition plate 18 to the discharge area 24, and the second gas flow path 41 from the discharge area 24 to the other opening 18B provided in the upper and lower partition plate 18. Gas flow path 42 . Laser medium gas flows through discharge region 24 in a direction perpendicular to optical axis 20A (FIG. 2). The discharge direction is perpendicular to both the direction in which the laser medium gas flows and the optical axis 20A. A circulation path for circulating the laser medium gas is formed by the blower chamber 17 , the first gas flow path 41 , the discharge region 24 , and the second gas flow path 42 . The blower 29 generates the flow of the laser medium gas indicated by the arrow, so that the laser medium gas circulates in the circulation path.

A heat exchanger 43 is accommodated in the circulation path in the blower chamber 17 . The laser medium gas heated in the discharge region 24 is cooled by passing through the heat exchanger 43 , and the cooled laser medium gas is supplied to the discharge region 24 again.

FIG. 4 is a diagram showing the positional relationship of the discharge electrode 21, the electrode case 22, and the diaphragm 60 when viewed from the front. In FIG. 4 , the electrode box 22 is hatched. A pair of discharge electrodes 21 facing up and down are fixed to electrode boxes 22, respectively. The first gas flow path 41 and the second gas flow path 42 of the laser medium gas are divided by the partition plate 40 attached to the electrode box 22 . In addition, FIG. 3 schematically shows the partition plate 40 , and the shape of the partition plate 40 shown in FIG. 4 is different from the shape of the partition plate 40 schematically shown in FIG. 3 .

The laser medium gas flows from the first gas flow path 41 to the second gas flow path 42 through the space between the pair of electrode cases 22 . In FIG. 4, the laser medium gas flow is indicated by arrows. A discharge region 24 is contained in the space between the pair of electrode boxes 22 . A rectifying plate 44 is arranged at the end where the laser medium gas flows into the space between the pair of electrode boxes 22 .

A diaphragm 60 is arranged at a position overlapping the discharge region 24 . When viewed from the front, the aperture 60 includes a passage area 60A through which the laser beam passes and a light shielding area 60B arranged around it. Passing region 60A is included in discharge region 24 when viewed from the front. The ratio of the dimensions of the passing region 60A in two directions perpendicular to each other in a plane perpendicular to the optical axis 20A ( FIG. 2 ) of the optical resonator 20 is variable. In addition, the passing area of the other aperture 70 ( FIG. 2 ) is a perfect circle, and its size does not change.

For example, the direction in which the laser medium gas flows (in FIG. 4, the horizontal direction) is defined as the first direction D1, and the direction in which the pair of discharge electrodes 21 are separated (in FIG. 4, the vertical direction) is defined as the first direction D1. 2 Direction D2. The size of the first direction D1 passing through the region 60A is variable, and the size of the second direction D2 is fixed. When the size of the passing region 60A in the first direction D1 changes, the ratio (hereinafter, referred to as aspect ratio) of the passing region 60A in the first direction D1 to the size of the second direction D2 changes. In FIG. 4 , the passing region 60A whose size in the first direction D1 is smaller than the passing region 60A shown by the solid line is indicated by a dotted line.

Next, the structure of the diaphragm 60 will be described with reference to FIGS. 5A to 5C . FIG. 5A is a perspective view of the aperture 60 . The aperture 60 includes a first member 61 and a second member 62 . The second member 62 includes two components 62A, 62B. The first member 61 is a plate (for example, a metal plate) arranged perpendicular to the optical axis 20A of the optical resonator 20 ( FIG. 2 ), and an opening 63 overlapping the path of the laser beam is provided on the plate. The size of the opening 63 is constant.

The two components 62A and 62B of the second member 62 are arranged at positions across the optical axis 20A along the first direction D1 when viewed from the front. Each of the two parts 62A, 62B is a plate material arranged vertically with respect to the optical axis 20A. The opposing peripheries of the two components 62A and 62B are curved inwardly and concavely.

The two parts 62A and 62B of the second member 62 are supported so as to be movable in the first direction D1 by the slide mechanism 65 . The guide surface of the sliding mechanism 65 is fastened to the resonator base 26 ( FIG. 2 ). The two components 62A, 62B are independently movable in the first direction D1. When the two components 62A, 62B are moved in the first direction D1, the relative positional relationship between the opening 63 of the first member 61 and the two components 62A, 62B changes when viewed from the front. If the two parts 62A, 62B are moved in a direction close to the optical axis 20A from the state where the two parts 62A, 62B do not overlap with the opening 63, then the two parts 62A, 62B overlap with a part of the opening 63, and the opening 63 is viewed from the first direction. Both sides of D1 close part of the opening 63 . For example, the two components 62A and 62B close the region extending from the periphery of the opening 63 to the inside. The area of the closed region of the opening 63 is changed by moving the two components 62A, 62B of the second member 62 .

5B and 5C are front views of the first member 61 and the second member 62 . FIG. 5B shows a state where the two parts 62A, 62B of the second member 62 do not overlap the opening 63 of the first member 61 . In this case, the opening 63 of the first member 61 coincides with the passage area 60A of the diaphragm 60 .

FIG. 5C shows a state where two parts 62A, 62B of the second member 62 overlap with a part of the opening 63 of the first member 61 . A region of the opening 63 that does not overlap the second member 62 coincides with the passing region 60A of the diaphragm 60 . When the two parts 62A and 62B of the second member 62 close a part of the opening 63 , the size of the first direction D1 passing through the region 60A becomes smaller. The dimension in the second direction D2 of the passing region 60A is the same as the dimension in the second direction D2 of the opening 63 and does not change.

Next, the excellent effect of the above-mentioned embodiment will be described. When performing processing in which a pulsed laser beam output from a laser oscillator is incident on an object to form a plurality of holes, the pulsed laser beam is sequentially incident on a plurality of positions where holes are to be formed. If the distance from the previously processed hole to the next hole to be processed becomes longer, the moving distance of the incident position of the pulsed laser beam becomes longer, so the time from the previous shot to the next shot may be longer. lengthen. Therefore, the frequency of repetition of the pulses varies under the influence of the distribution of holes to be formed. In order to make the shape of the formed hole uniform, it is better to keep the shape of the beam spot unchanged even if the repetition frequency of the pulse changes.

The inventors of the present invention conducted the following evaluation experiments, changing the repetition frequency of the pulse of the laser oscillator 12, and observing The shape of the beam spot of the laser beam. In the evaluation experiment, the passage area 60A of the diaphragm 60 was set as a perfect circle.

Fig. 6 is a graph showing the results of evaluation experiments. The horizontal axis represents the repetition frequency of pulses in the unit "kHz", and the vertical axis represents the beam spot sizes in the first direction D1 and the second direction D2 in relative values. The circular mark and the triangular mark in the graph represent the dimension in the first direction D1 and the dimension in the second direction D2, respectively. When the pulse repetition frequency is an arbitrary value, the size of the beam cross section in the first direction D1 is larger than the size in the second direction D2. Thereby, even if the apertures 60 and 70 whose passing areas are perfect circles are used, the beam profile will not become a perfect circle, but will become horizontally long. This is because the state of oscillation in the first direction D1 and the second direction D2 is different due to the influence of the laser dielectric gas flow and the spatial inhomogeneity of the discharge.

When the repetition frequency of the pulse is decreased, the size of the beam profile becomes larger. However, the increase in size in the first direction D1 is larger than the increase in size in the second direction D2. This is because the non-uniformity of the discharge state in the direction of the gas flow of the laser medium (the first direction D1) is more affected by the change in the repetition frequency of the pulse than the non-uniformity of the discharge state in the second direction D2. influences. When the repetition frequency of the pulse is lowered, the shape of the beam cross-section becomes more deformed from a perfect circle.

In this embodiment, by changing the size of the passing region 60A of the aperture 60 in the first direction D1, the shape of the beam cross section can be made close to a perfect circle. For example, in order to reduce the pulse repetition frequency and increase the beam profile along the first direction D1, it is only necessary to reduce the size of the passing region 60A in the first direction D1.

By adjusting the aspect ratio of the passing region 60A according to the repetition frequency of the pulse, even if the repetition frequency of the pulse is changed, it is possible to maintain the state where the beam profile is substantially circular.

Moreover, in this embodiment, since part of the opening 63 (FIG. 5A) of the first member 61 is closed from both sides of the first direction D1, even if the size of the first direction D1 passing through the region 60A is changed, the passage through the region 60A The position of the center of geometry does not move either. Therefore, even if the size of the first direction D1 passing through the region 60A is changed, the central axis of the laser beam does not shift.

Next, modifications of the above-described embodiment will be described. In the above-mentioned embodiment, the aspect ratio of the passage region 60A ( FIG. 4 ) of the front aperture 60 ( FIG. 2 ) is made variable, but the aspect ratio of the passage region of the rear aperture 70 may also be made variable. . Furthermore, the aspect ratios of the passing regions of the two apertures 60 and 70 may be made variable.

In the above-mentioned embodiment, the size of the second direction D2 of the passage area 60A of the aperture 60 is fixed, and the size of the first direction D1 is made variable, but the size of the first direction D1 can also be set as fixed, The dimension of the second direction D2 is made variable. In this case, the opening 63 ( FIG. 5A ) provided in the first member 61 may have an oblong shape along the second direction D2, and the second member 62 may be composed of two divided members along the second direction. In order to reduce the repetition frequency of pulses, it is only necessary to increase the size of the second direction D2 passing through the region 60A. Thereby, distortion from the perfect circle of the beam cross section can be reduced.

In addition, both the size of the first direction D1 and the size of the second direction D2 passing through the region 60A may be made variable. Thereby, the degree of freedom of adjustment of the shape of the beam cross section can be improved.

In the above-mentioned embodiment, the optical resonator 20 having a single linear optical axis 20A (FIG. 2) is constituted by a pair of resonator mirrors 25, but it is also possible to arrange other various mirrors to constitute a folded optical resonator. In this case, the optical resonator has, for example, a zigzag optical axis, and along the zigzagging optical axis between a pair of resonator mirror plates at both ends, the laser beam is confined. The aperture may be arranged at any position on the path of the zigzag-shaped laser beam closed in the optical resonator.

Next, a laser oscillator based on another embodiment will be described with reference to FIG. 7 . Hereinafter, a description of the laser oscillator and the common configuration based on the embodiments shown in FIGS. 1 to 6 will be omitted.

FIG. 7 is a cross-sectional view perpendicular to the optical axis 20A of the laser oscillator according to this embodiment. The first member 61 of the aperture 60 is fixed to the resonator base 26 . The two parts 62A and 62B of the second member 62 are supported on the resonator base 26 via the slide mechanism 65 . Rods 66A, 66B are respectively connected to the two parts 62A, 62B of the second member 62 . The rods 66A, 66B extend from the two parts 62A, 62B in the first direction D1, respectively, and are drawn out of the chamber 15 through the side wall of the chamber 15 . The portion where each rod 66A, 66B passes through the side wall of the chamber 15 is ensured to be airtight by a sealing structure 67A, 67B comprising an O-ring.

When the levers 66A, 66B are operated from outside the chamber 15 to move in the first direction D1, the two components 62A, 62B of the second member 62 move in the first direction D1. Thereby, the aspect ratio of the passing region 60A changes. The rods 66A, 66B function as an aspect ratio changing mechanism that changes the aspect ratio passing through the region 60A.

Next, the excellent effect of this embodiment will be described. In this embodiment, the two components 62A, 62B of the second member 62 can be moved in the first direction D1 from the outside of the chamber 15 through the rods 66A, 66B. Therefore, the aspect ratio of the passage area 60A of the diaphragm 60 can be adjusted while observing the shape of the beam cross section with the beam profiler 50 ( FIG. 1 ) while the laser oscillator 12 is oscillating. This makes it possible to easily adjust the beam profile to approach a perfect circle.

Next, referring to FIG. 8 , the laser oscillator based on other embodiments will be further described. Hereinafter, a description of the laser oscillator and the common configuration based on the embodiments shown in FIGS. 1 to 6 will be omitted.

FIG. 8 is a perspective view of the aperture 60 used in the laser oscillator according to this embodiment. In the embodiment shown in FIGS. 1 to 6 , the second member 62 ( FIG. 5A ) is divided into two parts along the first direction D1. In contrast, in this embodiment, neither the first member 61 nor the second member 62 is divided. Like the first member 61, the second member 62 is formed of a plate material provided with an opening 64. As shown in FIG. The first member 61 and the second member 62 are supported so as to be independently movable in the first direction D1 by the slide mechanism 65 .

When the aperture 60 is viewed from the front, the area where the opening 63 of the first member 61 and the opening 64 of the second member 62 overlap coincides with the passing area 60A of the aperture 60 . If the relative positional relationship between the first member 61 and the second member 62 in the first direction D1 is changed, the size of the passing region 60A in the first direction D1 will change. In addition, the size of the passing region 60A in the second direction D2 also changes, but since the amount of change is small, the aspect ratio of the passing region 60A changes. Furthermore, when the first member 61 and the second member 62 are moved in opposite directions by an equal distance, the size of the passing region 60A in the first direction changes while the central position of the passing region 60A is fixed.

Next, the excellent effect of this embodiment will be described. In this embodiment, by changing the aspect ratio of the passing region 60A of the aperture 60, similar to the embodiments shown in FIGS. 1 to 6, even if the repetition frequency of the pulse is changed, the beam profile can maintain a substantially circular state. .

The above-described embodiments are examples, and it goes without saying that partial replacement or combination of structures shown in different embodiments is possible. Regarding the same function and effect based on the same structure of multiple embodiments, it is not mentioned in sequence for each embodiment. Also, the present invention is not limited to the above-described embodiments. For example, it is obvious to those skilled in the art that various changes, improvements, combinations, etc. can be made.

11: Stand 12:Laser oscillator 15: chamber 16: Optical room 17: Blower room 18: Upper and lower partitions 18A, 18B: opening 19: Bottom plate 20: Optical resonator 20A: optical axis 20B: Region where light is enclosed between a pair of resonator mirrors 21: Discharge electrode 22: Electrode box 23: electrode support member 24:Discharge area 25: Resonator lens 26: Resonator base 27: Optical resonator support member 28: Light-transmitting window 29: Blower 40: Partition board 41: 1st gas flow path 42: Second gas flow path 43: Heat exchanger 44: Rectifier board 45: Support part 50: Beam Analyzer 60: Aperture 60A: through the area 60B: shading area 61: 1st component 62: 2nd member 62A, 62B: Parts of the second member 63: Opening of the first member 64: Opening of the second member 65: sliding mechanism 66A, 66B: Rod 67A, 67B: sealed structure 70: Aperture 80: Processing device 81: Beam shaping optical system 82:Workbench 90: Object to be processed 100: common base

[ Fig. 1 ] is a schematic diagram of a laser processing apparatus equipped with a laser oscillator according to this embodiment. [ Fig. 2 ] is a cross-sectional view including an optical axis of a laser oscillator based on an embodiment. [ Fig. 3 ] is a cross-sectional view perpendicular to the optical axis of the laser oscillator according to the embodiment. [FIG. 4] It is a figure which shows the positional relationship of the discharge electrode, an electrode case, and an aperture seen from the front. [FIG. 5A] is a perspective view of the aperture, and [FIG. 5B and FIG. 5C] are front views of the first member and the second member of the aperture. [Fig. 6] is a graph showing the results of an evaluation experiment in which the beam diameter of the beam spot (beam spot) of the laser beam was measured at a position advancing a certain optical path length from the light transmission window of the laser oscillator while changing the repetition frequency of the pulse. . [ Fig. 7 ] is a cross-sectional view perpendicular to the optical axis of a laser oscillator according to another embodiment. [ Fig. 8 ] A perspective view of an aperture used in a laser oscillator according to yet another embodiment.

20A: optical axis

60: Aperture

60A: through the area

61: 1st component

62: 2nd member

62A: Parts of the second member

62B: Parts of the second member

63: Opening of the first member

65: sliding mechanism

Claims (8)

A kind of aperture, is the aperture that is arranged on the path of the laser beam that is sealed in the optical resonator, is characterized in that it divides: the passage area that the laser beam that is enclosed in the aforementioned optical resonator passes through; And arranges in the aforementioned passing area The surrounding light-shielding area, and in the plane perpendicular to the optical axis of the aforementioned optical resonator, the aspect ratio as the ratio of the size of the aforementioned passing area in two directions orthogonal to each other is variable, and the inner side of the aforementioned aperture is curved shape. The aperture according to claim 1, wherein, in a plane perpendicular to the optical axis of the optical resonator, the size of the passing region in the first direction of the two directions perpendicular to each other is variable, and The size of the passing area in the second direction perpendicular to the first direction is constant. The aperture according to Claim 2, which includes: a first member provided with an opening with a constant size; and a second member configured to be supported so as to be movable in the first direction relative to the first member , and by moving along the first direction, a part of the area entering from the opening periphery of the first member to the inner side can be closed. In the opening of the first member, the area that is not closed by the second member becomes the passage area. The aperture according to claim 3, wherein the second member includes two zeros divided along the first direction Components; the two parts of the aforementioned second member are configured to close part of the opening of the aforementioned first member from both sides in the aforementioned first direction. A laser oscillator has: an optical resonator, which seals a laser beam; and an aperture, which divides: a passing area through which the laser beam sealed in the aforementioned optical resonator passes; and is arranged around the aforementioned passing area and in a plane orthogonal to the optical axis of the aforementioned optical resonator, the aspect ratio, which is the ratio of the dimensions of the aforementioned passing area in two directions orthogonal to each other, is variable; and the cavity, which is The aforementioned optical resonator, the aforementioned aperture, and the laser medium gas are accommodated; and an aspect ratio changing mechanism is operated from outside the chamber to change the aspect ratio of the aforementioned passing area of the aforementioned aperture, and the inner side of the aforementioned aperture is in a curved shape. The laser oscillator according to claim 5, wherein the size of the passing region in the first direction among the two directions orthogonal to each other in the plane perpendicular to the optical axis of the optical resonator is variable , the size of the aforementioned passage area in the second direction perpendicular to the aforementioned first direction is constant. The laser oscillator as described in Claim 6, wherein the aforementioned aperture includes: a first member, which is provided with an opening with a constant size; and a second member, which is configured to be supported relative to the first The member moves along the aforementioned first direction, and by moving along the aforementioned first direction, the A portion of the opening peripheral edge of the first member enters the inside and is closed, and the aspect ratio changing mechanism is capable of moving the second member relative to the first member in the first direction. The laser oscillator according to claim 7, wherein the second member includes two parts divided along the first direction; the two parts of the second member are formed from the first direction Both sides of the aforementioned first member can close the opening of the aforementioned first member, and the aforementioned aspect ratio changing mechanism is configured so that the two parts of the aforementioned second member can respectively move along the aforementioned first direction.

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