KR20200083249A - Beam rotator unit and laser processing apparatus - Google Patents

Abstract

The present invention relates to a laser processing apparatus and a beam rotator unit. An object of the present invention is to implement taperless processing by trepanning processing. In a processing apparatus in which a beam rotator, a galvano scanner, and an fθ lens are installed in order on an optical path of laser light from a source to a workpiece, an operation of displacing the laser light by the galvano scanner in order that the scanning trajectory becomes a closed curve such as a circle at the scanning position, and an operation of rotating the scanning direction while tilting the scanning direction of the laser light by the beam rotator and the fθ lens are synchronized. In addition, the laser light is incident on the workpiece at an incident angle at which the outermost side of a passing range of the laser light is perpendicular to the workpiece.

Description

Laser processing device and beam rotator unit {BEAM ROTATOR UNIT AND LASER PROCESSING APPARATUS}

The present invention relates to an apparatus for processing a workpiece using a laser beam and a beam rotator unit used in the apparatus, and more particularly, to an apparatus and unit for processing a hole through a workpiece.

As one aspect of processing using laser light, trepanning processing, in which a laser beam is punched on a workpiece, for example, to perform drilling while leaving a core material, is widely known. The trepanning process is used for processing a hole having a plane size larger than the beam diameter of the laser beam, or for taking out a core material having a plane size larger than the beam diameter.

On the other hand, as a technique of forming a recess on the surface of an object to be processed by laser light, in addition to a pair of wedge prism for adjusting the angle of incidence and a wedge prism for adjusting the radius of rotation, each of which is rotated at high speed by a servo motor. By controlling the shape of the side of the recess by using a laser processing device including a beam rotator incorporating a gradium lens, which is an aberration-free lens, and a processing head including a galvano scanner The technology is already known (for example, see Patent Document 1).

Japanese Patent Publication No. 2014-133242

In other words, in the case where the workpiece is punched by trepanning, in other words, the hole diameter is uniform in the thickness direction. In other words, a straight column shape with a tapered hole (for example, a positive cylinder) Shape), there is a certain demand.

However, in the case of the trepanning process by scanning with the laser beam of the most common irradiation sun irradiated downward toward the sun focusing on the position to be processed, the side of the hole becomes tapered, A straight columnar hole cannot be obtained.

On the other hand, Patent Document 1 discloses an aspect in which a side surface of a concave portion is perpendicular to a surface of a work piece when forming the concave part with respect to the work piece, but the taperless trepanning process also suggests a lower start. It is not made. In addition, in the processing apparatus disclosed in Patent Document 1, it is an essential aspect that a beam rotator is provided with a condensing optical system as a condensing lens, a gradation lens.

This invention is made|formed in view of the said subject, and aims at realizing the taperless punching process by a trepanning process, and furthermore, realizing the trepanning process which can control the taper state.

In order to solve the above problems, the invention of claim 1 is an apparatus for processing the workpiece by irradiating a laser beam onto the workpiece, an emission source of the laser beam, and a stage where the workpiece is placed horizontally during processing. And a beam rotator, a galvano scanner, and an fθ lens, which are sequentially installed from the side of the source, on the optical path of the laser light from the source to the work piece placed on the stage. It is provided with a control means for controlling the operation of, the laser light having passed through the fθ lens is irradiated to the workpiece from above, and the beam rotator shifts the incident laser light to a position parallel to the incident direction. Together, the laser light is emitted while rotating with an axis of rotation of the incident direction of the laser light with respect to the beam rotator, and the galvano scanner is installed so that the irradiation position in the workpiece of the laser light can be displaced. As the laser light that has passed through the beam rotator and the galvano scanner passes through the fθ lens, the irradiation direction with respect to the irradiation position is rotated while maintaining the incident angle with respect to the irradiation position at a predetermined angle, and the control means comprises: The galvano scanner synchronizes an operation of displacing the irradiation position of the laser light along a predetermined closed curve, and rotating the irradiation direction of the laser light with respect to the irradiation position by the beam rotator and the fθ lens. It is characterized by.

The invention of claim 2 is the laser processing apparatus according to claim 1, characterized in that the laser beam is incident on the workpiece at an incident angle at which the outermost side of the laser beam passing range is perpendicular to the workpiece.

The invention of claim 3 is the laser processing apparatus according to claim 2, wherein the control means comprises: an operation in which the galvano scanner sets the irradiation position of the laser light along a predetermined circle, and the beam rotator; The fθ lens is characterized by synchronizing an operation of rotating the irradiation direction of the laser light with respect to the irradiation position.

The invention of claim 4 is the laser processing apparatus according to claim 3, wherein the stage is freely installed and raised, and the control means is a timing in which displacement of the laser beam along the circle of the irradiation position is 1 week or multiple weeks Each time, the stage is moved to raise the workpiece.

The invention of claim 5 is a beam rotator unit used in an apparatus for processing the workpiece by irradiating a laser beam onto the workpiece, a beam rotator, a galvano scanner, which is sequentially installed on an optical path of the laser beam, fθ lens, and a control means for controlling the operation of each part of the beam rotator unit, the beam rotator shifts the incident laser light to a position parallel to the incident direction, and the The laser light is emitted while rotating with the rotational direction as the rotational axis, and the galvano scanner is provided so that the irradiation position in the workpiece of the laser light is displaceable, and the laser light is configured to connect the beam rotator and the galvano scanner. As the rough laser light passes through the fθ lens, while the incident angle to the irradiation position is maintained at a predetermined angle, the irradiation direction to the irradiation position is rotated, and the control means includes: It is characterized in that the operation of displacing the irradiation position along a predetermined closed curve and the operation of rotating the irradiation direction of the laser light with respect to the irradiation position by the beam rotator and the fθ lens are synchronized.

According to the inventions of claims 1 to 5, perforation processing with laser light is achieved, intentionally controlling the state of the taper.

In particular, according to the invention of claims 3 and 4, tapered punching is realized.

1 is a view schematically showing the configuration of the processing apparatus 100.
2 is a view for explaining the role of the beam rotator 20 and fθ lens 40.
3 is a view schematically showing the shape of the laser beam LB during the trepanning process by the processing apparatus 100.
4 is a schematic cross-sectional view showing the progress of taperless processing, which is realized by performing a trepanning process in the processing apparatus 100.
5 is a view showing an enlarged image of a through hole obtained in Example 1. FIG.
6 is a view showing an enlarged image of a through hole obtained in Example 2.
7 is a view showing an enlarged image of a through hole obtained in Example 3.

(Form for carrying out the invention)

<Overview of processing equipment>

1 is a diagram schematically showing a configuration of a processing apparatus 100 for performing trepanning according to the present embodiment. The processing apparatus 100 is a control that controls the operation of the laser beam LB source 10, the beam rotator 20, the galvano scanner 30, the fθ lens 40, and each part of the apparatus. The module 50 and the stage 70 on which the workpiece (hereinafter, also referred to as a work piece) W are placed are mainly provided.

In the processing apparatus 100, the beam rotator 20 and the galvano scanner 30 are schematically illustrated in the optical path of the laser light LB from the source 10 to the work W placed on the stage 70. ) And fθ lens 40 are installed in this order from the side of the source 10. And, under the control of the control module 50, the laser light LB emitted from the source 10, and sequentially passed through the beam rotator 20, the galvano scanner 30, and the fθ lens 40, By being irradiated to the work W, the work W is processed. In Fig. 1, mirrors 61 and 62 are provided between the source 10 and the beam rotator 20 and between the beam rotator 20 and the galvano scanner 30, respectively. By reflecting the laser light LB with 61 and 62, the optical path of the laser light LB is bent, but this is in accordance with the circumstances of the city and is not an essential aspect. Alternatively, in view of the configuration of the processing apparatus 100, more mirrors may be used, and the optical path of the laser beam LB may be further bent.

The control module 50 is an on/off operation of emitting laser light LB from the emission source 10, a rotation operation of the beam rotator 20, or a galvano not shown in the galvano scanner 30 The rotation (or oscillation) operation of the mirror, the elevation operation of the stage 70, and the like are controlled.

The stage 70 is a portion where the workpiece W is fixed during processing. The laser light LB is irradiated from the fθ lens 40 positioned above the work W placed on the stage 70. The stage 70 is freely provided with a lift in the vertical direction, and is lifted in response to a drive signal from the control module 50. Alternatively, the mode may be configured such that a two-axis movement (translation) operation or a rotation operation in a horizontal plane can be performed. In this case, these operations are also performed in response to the drive signal from the control module 50.

As the laser light LB, those of various wavelengths may be selected depending on the material or thickness of the work W, the desired processing mode, etc., and the source 10 is also prepared to be capable of emitting the selected laser light LB It's good to be.

2 is a view for explaining the roles of the beam rotator 20 and the fθ lens 40. In addition, in FIG. 2, for simplicity of explanation, the galvano scanner 30 that is originally provided on the optical path between the beam rotator 20 and the fθ lens 40 is omitted. In addition, the incident direction when the laser light LB enters the beam rotator 20 (more specifically, the prism 21) is taken as the axis AX1.

As shown in Fig. 2, the beam rotator 20 has a configuration in which a pair of prisms 21 and 22 are inserted inside the hollow motor 23. The pair of prisms 21 and 22 are positioned at a position where the laser beam LB incident on the prism 21 along the axis AX1 is shifted by a predetermined distance parallel to the axis AX1. ), it is made to be injected into the hollow motor 23 to exit. In other words, the pair of prisms 21 and 22 has the position of the optical path of the laser beam LB when exiting the beam rotator 20, and the laser beam LB when it enters the beam rotator 20. It is made to be inserted into the hollow motor 23 so as to shift a predetermined distance from the optical path position.

More specifically, the laser light LB from the prism 21 toward the prism 22 is first inclined by a predetermined angle α with respect to the axis AX1, but from the prism 22 (that is, the beam rotator 20) From) The exit direction of the laser beam LB when exiting outside is parallel to the axis AX1.

In addition, in the beam rotator 20, the hollow motor 23 is rotated with the axis AX1 as the rotation axis, as indicated by arrow AR2. As a result of the combination of this rotation and the above-described shift, the emission of the laser light LB from the beam rotator 20 is made of the sun rotating parallel to the axis AX1 and around the axis AX1.

If the contribution of the galvano scanner 30 is ignored (or if the galvano scanner 30 does not change the position of the laser light LB), the laser light LB emitted from the beam rotator 20 is Maintaining the state parallel to the axis AX1, the fθ lens 40 is formed with the axis AX1 as the center of the axis. The fθ lens 40 is provided so as to deflect the incident laser beam LB toward a position on the extension line of the axis AX1 in the work W. Accordingly, the laser light LB is irradiated to the work W at a predetermined incident angle β.

However, as described above, the beam rotator 20 is rotating. Therefore, the incident position of the laser light LB with respect to the fθ lens 40 also rotates around the axis AX1, and accordingly the exit position of the laser light LB from the fθ lens 40 is also the axis AX1. It will rotate around. However, since the optical path position of the laser light LB shifted by the beam rotator 20 is isotropic with respect to the axis AX1, the laser light LB is irradiated to the same position of the work W.

That is, the beam rotator 20 and the fθ lens 40 ignore the contribution of the galvano scanner 30, and the laser light LB has a predetermined incident angle β with respect to the same position of the work W. It means that it has the effect of injecting while rotating while maintaining ). In other words, it can be said that the beam rotator 20 and the fθ lens 40 have a rotational effect that constantly changes the direction of incidence of the laser light LB with respect to the irradiation position.

In addition, in the actual processing apparatus 100, as described above, the galvano scanner 30 is provided on the optical path between the beam rotator 20 and the fθ lens 40. The galvano scanner 30 is installed under the control of the control module 50 to displace the irradiation position of the laser light LB with respect to the work W to an arbitrary position as indicated by arrow AR1 in FIG. 1. It is done. More specifically, the galvano scanner 30 is freely provided with displacement in a predetermined range in the horizontal two-axis direction at the irradiation position of the laser light LB. Then, the operation of the galvano scanner 30 enables scanning of the work W by the laser light LB. In this case, the displacement of the irradiation position of the laser light LB (that is, scanning by the laser light LB) by the galvano scanner 30 virtually sets the axis AX1 to the original position (beam rotator). It can be considered to be displaced to a position parallel to the position where the laser light LB enters (20). Therefore, the irradiation of the laser beam LB is realized by the displacement of the irradiation position according to the operation of the galvano scanner 30 and the action of the beam rotator 20 and fθ lens 40 described above. This is achieved by combining with incident to the irradiation position while rotating while maintaining β).

<Trepaning processing>

Next, the trepanning process by the processing apparatus 100 which has the above-mentioned structure is demonstrated. 3 is a diagram schematically showing the shape of the laser beam LB during the trepanning process by the processing apparatus 100. 4 is a schematic cross-sectional view showing the shape of the progress of a taperless drilling process (hereinafter, also simply referred to as taperless processing), which is realized by performing a trepanning process in the processing apparatus 100.

In the following, for the sake of simplicity, as shown by arrow AR4 in FIG. 3, the irradiation position of the laser light LB (typically the converging point F) is a predetermined horizontal circle C. It is a case in which the trepanning process is performed in a manner in which displacement (circumference) is performed accordingly, that is, a scanning path by the laser light LB becomes a circle C.

The displacement (circular scanning) along the circle C of the laser beam LB is realized by driving the galvano scanner 30 based on the scanning signal from the control module 50. And in the processing apparatus 100 which concerns on this embodiment, the beam as shown by arrow AR3 in FIG. 3 in the displacement along the circle C of the laser beam LB by this galvano scanner 30 is shown. In the state in which the change in the direction of irradiation of the laser light LB due to the rotation of the rotator 20 is synchronized, the trepanning process is performed.

In addition, in actual processing, in a state in which the synchronization of the beam rotator 20 and the galvano scanner 30 is established, the control module 50 turns on the emission of the laser light LB with respect to the source 10 A signal is emitted, and the emission source 10 responds to this, and starts emitting the laser light LB.

More specifically, while the irradiation direction of the laser light LB with respect to the irradiation position is rotated by one rotation by the operation of the beam rotator 20, the laser light LB is circle C by the galvano scanner 30. Both operations are synchronously controlled so as to rotate the phase exactly one revolution. This is, according to the timing at which the control module 50 receives the timing signal emitted by the beam rotator 20 each time the hollow motor 23 rotates one time, the control module 50 with respect to the galvano scanner 30 , It is realized by giving a scanning signal for executing a scan that circumscribes the original (C) image.

In this case, the laser light LB is rotated in a conical enveloping surface CF having a virtual axis AX2 as a central axis orthogonal to the horizontal surface including the circle C on the circle C. , Will move along the circle (C). And, by the relationship between the irradiation position of the laser beam LB on the circle C and the rotational position in the envelope CF (the direction of irradiation of the laser beam as the irradiation position), during the trepanning process The shape of the through hole of is determined.

The taperless processing is one representative aspect. That is, when the synchronous control of the beam rotator 20 and the galvano scanner 30 by the control module 50 is, the laser light LB emitted from the fθ lens 40 is at any position on the circle C Also in the above, the passing range of the laser beam LB is included inside the circle C, and the outermost side of the passing range is orthogonal to the horizontal plane including the circle C on the circle C. In the aspect that follows the virtual axis AX2 to be performed, in other words, when the outermost side of the passage range is performed in an aspect perpendicular to the work W, tapered processing is realized.

It is also conceivable that the virtual axis AX2 has moved in parallel with the virtual axis AX1 shown in FIG. 2 with displacement of the irradiation position of the laser light LB by the galvano scanner 30. Therefore, the taperless processing does not depend on which position on the circle C the irradiation position moved by the galvano scanner 30 is, but the angle formed by the outermost side and the optical axis of the passing range of the laser light LB. It can also be said that the laser light LB is inclined under the conditions coinciding with the incident angle β realized by the beam rotator 20.

As an example, as shown in Fig. 4(a), for a plate-shaped work W horizontally disposed on the stage 70 not shown, the planned processing surface P along the thickness direction (cross-sectional view) Considering the case in which a hole having a diameter (D) in the shape of a pillar having a diameter (D) is to be drilled by taperless processing of the above-described sun along the line (in Fig. 4 shown as a linear shape), the laser light LB is first of all In the state where the laser light LB is incident at an incident angle β at which the outermost side of the passage range is perpendicular to the work W, as shown by arrow AR5, the irradiation direction is rotated, as indicated by arrow AR6, The irradiation position is displaced along the planned processing surface P. However, the incident angle β is preferably an angle at which no interference or reflection of laser light occurs. In addition, it is not always necessary that the outermost side of the laser beam LB's passing range is strictly perpendicular to the work W, and in practical use, it may be an angle close to vertical.

Subsequently, at each timing at which such displacement is at least one week or multiple weeks, in other words, at each timing at which the beam rotator 20 rotates the laser light LB one or more times, a drive signal from the control module 50 When the stage 70 operates in response, the work W is raised a predetermined distance. Thereby, the light-converging point F enters the inside of the work W in the thickness direction, and as shown in Fig. 4(b), the work W faces the thickness direction from the surface, and the processing scheduled surface P ), the processing groove (processing trace) G is gradually formed. At this time, the method of tilting or rotating the laser light LB remains at the start of processing, and therefore, the laser light LB does not protrude out of the planned processing surface P. In addition, the timing of the rise of the work W may be appropriately determined depending on the material of the work W, the intensity of the laser beam LB, and the like.

In addition, the elevation of the stage 70 may be a relative elevation with the fθ lens 40, and instead of the elevation of the stage 70 or with the elevation of the stage 70, an optical system including the fθ lens 40 The sun may be moved up and down without changing the optical distance in the optical system.

Alternatively, a mode in which the scan of the laser light LB by the operation of the galvano scanner 30 and the rise of the work W by the operation of the stage 70 are performed synchronously may be used. In this case, the light-converging point F of the laser light LB enters the inside of the work W while drawing a spiral trajectory.

As the scanning of the laser beam LB and the rise of the work W are repeated, finally, as shown in Fig. 4(c), the groove G follows the work surface P to be processed (W). ). Then, as shown by the arrow AR7, when the part of the cylindrical shape surrounded by the groove G is separated, as shown in Fig. 4(d), the side surface S is the front surface Wa and the back surface Wb of the work W. ) A through hole H perpendicular to both sides is formed. In short, taperless processing is completed.

In addition, when the thickness of the work W is thin, the surface Wa is moved along the planned surface P of the groove G without moving the work W upward by operating the stage 70 as described above. It is possible to penetrate from to the back surface Wb.

However, in the case of drilling a through hole having a cylindrical shape, it is necessary to make the scanning trajectory of the laser light LB a circle, but by making the shape of the closed curve (including a polygon) formed by the scanning trajectory different, a through hole of another shape is drilled. It is also possible. For example, if the galvano scanner 30 is controlled so that the scanning trajectory by the laser beam LB becomes a rectangular shape, processing to form a rectangular through hole is also possible, and at that time, the laser beam LB passes. If the relationship that the laser light LB is incident on the work W at an incidence angle perpendicular to the work W is formed on the outermost side of the range, the rectangular through-hole can be tapered.

As described above, according to the present embodiment, in the optical path of the laser light from the source to the workpiece, in the processing apparatus in which the beam rotator, the galvano scanner and the fθ lens are provided in this order, by the galvano scanner, Synchronize the operation of displacing the laser light so that the irradiation position is, for example, a closed curve such as a circle as a scanning trajectory, and rotating the irradiation direction while tilting the irradiation direction of the laser light by a beam rotator and an fθ lens, and adding Thus, by making the laser light enter the work piece at an incidence angle at which the outermost side of the laser beam passing range is perpendicular to the work piece, a tapered punching process can be performed on the work piece.

<Modification>

In the above-described embodiment, in order to realize taperless processing, laser light is incident on the outermost side of the laser beam passing range at an incident angle perpendicular to the workpiece, but instead, the laser beam passing range is maximized. When the laser light is incident on the sun, which is an inverse phase from the above-described embodiment, in which the laser light is incident at an incidence angle in which the inside is perpendicular to the workpiece, a perforation processing in which the through hole is tapered is preferable. In other words, the processing in which the shape of the taper is controlled can be intentionally performed. Furthermore, various hole-shaped perforations can be performed by changing the inclined state of the laser light stepwise or continuously through the entire process or in the middle of the process. This means that, by controlling the inclined state of the laser beam, it is possible to perform a puncturing process intentionally controlling the state of the taper.

[Example]

(Example 1)

In this embodiment, alumina ceramic plates with a thickness of 0.62 mm were punched with a diameter of 200 µm. The processing conditions were as follows.

Laser condition→wavelength=532nm, pulse width<50Hz, repetition frequency=100Hz, output=7.5W;

Beam rotator revolution=10000 rpm;

z-axis feed pitch=12㎛.

5 is an enlarged image of a through hole obtained by processing. Fig. 5(a) is a phase in which the alumina ceramic plate is divided into sections through a through hole, and the through hole is viewed from the side, and Fig. 5(b) is an image of the surface of the alumina ceramic plate after such division.

It is confirmed from FIG. 5 that the tapered through hole is satisfactorily formed.

(Example 2)

In this example, a SiC plate having a thickness of 0.36 mm was punched with a diameter of 300 µm. The processing conditions were as follows.

Laser condition→wavelength=532nm, pulse width<15Hz, repetition frequency=80Hz, output=4.0W;

Beam rotator revolution=5000 rpm;

z-axis feed pitch=20㎛.

6 is a view showing an enlarged image of a through hole obtained by processing. Fig. 6(a) is a view of the SiC plate after the SiC plate is divided into sections through the through hole, and Fig. 6(b) is an image of the surface of the SiC plate after the through hole is formed.

It is confirmed from FIG. 6 that the tapered through hole is satisfactorily formed.

(Example 3)

In this example, a Si plate having a thickness of 0.49 mm was bored with a diameter of 500 µm. The processing conditions were as follows.

Laser condition→wavelength=532nm, pulse width<15Hz, repetition frequency=50Hz, output=7.5W;

Beam rotator revolution=5000 rpm;

z-axis feed pitch=60㎛.

7 is a view showing an enlarged image of a through hole obtained by processing. Fig. 7(a) is a view of the Si plate after the Si plate is divided into sections through a through hole, and Fig. 7(b) is an image of the surface of the Si plate after forming the through hole.

It is confirmed from FIG. 7 that the tapered through hole is satisfactorily formed.

10: employee
20: beam rotator
21, 22: Prism
23: hollow motor
30: galvano scanner
40: fθ lens
50: control module
70: stage
100: processing device
LB: laser light
F: Condensing point
H: Through hole
P: Planned surface
W: Walk

Claims (5)

An apparatus for processing the workpiece by irradiating a laser beam to the workpiece,
The laser light source,
A stage in which the workpiece is placed horizontally during processing,
A beam rotator, a galvano scanner, and an fθ lens sequentially installed from the side of the source on the optical path of the laser light from the source to the workpiece placed on the stage;
It has a control means for controlling the operation of each part of the device,
The laser light that has passed through the fθ lens is irradiated to the workpiece from above,
The beam rotator shifts the incident laser light to a position parallel to the incident direction, and exits while rotating the incident direction of the laser light to the beam rotator as a rotation axis,
The galvano scanner is provided so that the irradiation position of the laser beam in the workpiece is displaceable,
In the laser light, the laser light that has passed through the beam rotator and the galvano scanner passes through the fθ lens, so that the irradiation direction with respect to the irradiation position is rotated while maintaining an incident angle with respect to the irradiation position at a predetermined angle. ,
The control means rotates the irradiation direction of the laser light with respect to the irradiation position by the operation of the galvano scanner to displace the irradiation position of the laser light along a predetermined closed curve, and the beam rotator and the fθ lens. A laser processing apparatus characterized by synchronizing a prescribing operation. According to claim 1,
The laser processing apparatus according to claim 1, wherein the laser light is incident on the work piece at an incident angle at which the outermost side of the laser beam passing range is perpendicular to the work piece. According to claim 2,
The control means includes: an operation in which the galvano scanner sets the irradiation position of the laser light along a predetermined circle, and by the beam rotator and the fθ lens, the laser light to the irradiation position is A laser processing apparatus characterized by synchronizing the operation of rotating the irradiation direction by one rotation. According to claim 3,
The stage is made up and down freely installed,
The control means is characterized in that the displacement of the laser beam along the circle of the irradiation position at a timing of 1 week or multiple weeks is moved to move the stage to raise the workpiece. A beam rotator unit used in an apparatus for processing the workpiece by irradiating a laser beam onto the workpiece,
A beam rotator, a galvano scanner, and an fθ lens that are sequentially installed on the optical path of the laser light, and control means for controlling the operation of each part of the beam rotator unit,
The beam rotator shifts the incident laser light to a position parallel to the incident direction, and exits while rotating the incident direction of the laser light to the beam rotator as a rotation axis,
The galvano scanner is provided so that the irradiation position of the laser beam in the workpiece is displaceable,
In the laser light, the laser light that has passed through the beam rotator and the galvano scanner passes through the fθ lens, so that the irradiation direction with respect to the irradiation position is rotated while maintaining an incident angle with respect to the irradiation position at a predetermined angle. ,
The control means rotates the irradiation direction of the laser light with respect to the irradiation position by the operation of the galvano scanner to displace the irradiation position of the laser light along a predetermined closed curve, and the beam rotator and the fθ lens. Beam rotator unit, characterized in that, to synchronize the operation.

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