JP2021051225A - Beam shaper, processing device, and processing method - Google Patents

Abstract

To provide a beam shaper with a simple configuration capable of suppressing rapid change in temperature of a workpiece.SOLUTION: A beam shaper (BS) provided herein comprises: an axicon lens (133), with a first end face (133a) and a second end face (133b), disposed on an optical path of a Gaussian beam (G'); and a rotating mechanism (135) for rotating the axicon lens (133) using a center axis (L1) of the Gaussian beam (G') incident on the first end face (133a) as a rotation axis. Defining a main axis (L2) as the normal of the first end face (133a) passing through an apex of the second end face (133b), the main axis (L2) and the center axis (L1) are out of alignment.SELECTED DRAWING: Figure 1

Description

The present invention relates to a beam shaper that converts a Gaussian beam into a Bessel beam. It also relates to a processing apparatus provided with such a beam shaper. Further, the present invention relates to a processing method using such a beam shaper.

Axicon lenses that convert a collimated Gaussian beam into a Bessel beam are widely used. Patent Document 1 discloses a beam shaper provided with an axicon lens (“laser beam shaping device” in Patent Document 1). The Bessel beam emitted from the axicon lens has high power in the interference region. Therefore, by forming the interference region of the Bessel beam emitted from the axicon lens on the work, efficient processing becomes possible.

JP-A-2017-142402

Laser processing of metals has the following problems. First, when the power of the laser beam irradiating the work is high, the molten metal scattered from the periphery of the keyhole becomes spatter (it is necessary to remove the spatter after laser processing). Secondly, rapid cooling after laser irradiation causes thermal strain or cracks in the work. Third, if the molten metal solidifies before the gas mixed in the molten metal is dissipated, blow holes occur.

In order to avoid such a problem, a technique called wobbling irradiation of laser light is used. In wobbling irradiation, the sudden temperature change of the work can be suppressed by swaying the locus of the irradiation point of the laser beam, and the above-mentioned problem can be suppressed.

However, in the conventional beam shaper, it has been difficult to realize the wubbing of the Bessel beam emitted from the axicon lens. This is because the interference region of the Bessel beam emitted from the axicon lens is formed in the vicinity of the axicon lens. For this reason, it is difficult to provide a mechanism for wobbling the Bessel beam (movable mirror, rotatable wedge substrate, etc.) between the axicon lens and the work.

One aspect of the present invention has been made in view of the above problems. One aspect of the present invention is to realize a beam shaper, a processing device, or a processing method capable of suppressing a sudden temperature change of a work with a simple configuration.

The beam shaper according to the first aspect of the present invention includes a first end face having a planar shape and a second end face having a conical surface shape, and an axicon lens arranged on the optical path of a Gaussian beam and the first end face. It is provided with a rotation mechanism for rotating the axicon lens with the central axis of the Gaussian beam incident on the end surface of the lens as a rotation axis. In the beam shaper according to the first aspect of the present invention, a configuration is adopted in which the main axis and the central axis are deviated from each other with the normal of the first end face passing through the apex of the second end face as the main axis. There is.

According to the above configuration, a beam shaper capable of suppressing a sudden temperature change of the work can be realized with a simple configuration.

The beam shaper according to the second aspect of the present invention is configured such that the main axis is tilted with respect to the central axis in the beam shaper according to the first aspect described above.

According to the above configuration, since the main axis is tilted with respect to the optical axis, the center of the Bessel beam generated by passing through the axicon lens is formed at a position deviated from the rotation axis. .. Then, the rotation mechanism rotates the axicon lens around the rotation axis. Therefore, the beam shaper according to the second aspect can make the locus of the center of the Bessel beam circular.

The beam shaper according to the third aspect of the present invention is configured such that the main axis is parallel to the central axis and is separated from the central axis in the above-mentioned beam shaper according to the first or second aspect. Has been done.

According to the above configuration, the center of the Bessel beam generated by passing through the axicon lens because the main axis is parallel to the central axis and is separated from the central axis is formed. It is formed at a position deviated from the rotation axis. Then, the rotation mechanism rotates the axicon lens around the rotation axis. Therefore, the beam shaper according to the second aspect can make the locus of the center of the Bessel beam circular.

The beam shaper according to the fourth aspect of the present invention is configured such that the main axis is separated from the central axis by 0.1 mm or more in the beam shaper according to the third aspect described above.

According to the above configuration, the center of the Bessel beam generated by passing through the axicon lens can be reliably deviated from the rotation axis. Therefore, the locus of the center of the Bessel beam can be surely made into a circular shape.

In the processing apparatus according to the fifth aspect of the present invention, a configuration is adopted in which a processing head including the beam shaper according to any one of the first to third aspects of the present invention is provided and the work is irradiated with a Bessel beam output from the beam shaper. ing.

According to the above configuration, it is possible to realize a processing apparatus capable of suppressing a sudden temperature change of the work with a simple configuration.

The processing method according to aspect 6 of the present invention includes a first end face that is planar and a second end face that is conical, and transmits an axicon lens arranged on the optical path of the Gaussian beam. This is a processing method for irradiating a work with a Bessel beam generated by the above method, and includes a step of rotating the axicon lens with the central axis of the Gaussian beam incident on the first end face as a rotation axis.
In the processing method according to the fifth aspect of the present invention, a configuration is adopted in which the main axis and the central axis are deviated from each other with the normal of the first end face passing through the apex of the second end face as the main axis. ing.

According to the above configuration, a processing method capable of suppressing a sudden temperature change of the work can be realized with a simple configuration.

According to one aspect of the present invention, it is possible to realize a beam shaper, a processing device, or a processing method capable of suppressing a sudden temperature change of a work.

(A) is a block diagram showing a configuration of a processing apparatus according to an embodiment of the present invention. (B) and (c) are cross-sectional views showing the structure of a processing head included in the processing apparatus. Each of (a), (b), and (c) is a graph showing the intensity distribution of the Bessel beam on the y-axis obtained by the processing apparatus shown in FIG. 1, and the intensity distribution of the Bessel beam on the xy plane. It is a graph which shows. It is sectional drawing which shows the structure of the modification of the beam shaper BS shown in (b) and (c) of FIG. Each of (a), (b), and (c) is a graph showing the intensity distribution of the Bessel beam on the y-axis obtained by a processing apparatus equipped with the beam shaper BS of the modified example shown in FIG. 3, and the Bessel. It is a graph which shows the intensity distribution on the xy plane of a beam.

[First Embodiment]
(Configuration of processing equipment)
The configuration of the processing apparatus 1 according to the embodiment of the present invention will be described with reference to FIG. In FIG. 1, FIG. 1A is a block diagram showing a configuration of a processing apparatus 1, and FIGS. 1B and 1C are cross-sectional views of a processing head 13 included in the processing apparatus 1. Here, the cross section shown in FIG. 1 (b) is an AA'cross section obtained by cutting the processing head 13 along the AA' line shown in FIG. 1 (c), and the cross section shown in FIG. 1 (c) is processed. It is a BB'cross section of the head 13 cut along the BB' line shown in FIG. 1 (b).

The processing device 1 is a device for processing the work W using a laser beam, and as shown in FIG. 1A, the laser light source 11, the delivery fiber 12, the processing head 13, and the movable stage 14 And have.

The laser light source 11 is a device that generates laser light. The delivery fiber 12 is an optical fiber that guides the laser light generated by the laser light source 11. The processing head 13 is a device that irradiates the work W with a laser beam guided through the delivery fiber 12. The movable stage 14 is a device that moves the work W in a direction orthogonal to the traveling direction of the laser beam emitted from the processing head 13. As the laser light source 11, for example, a fiber laser is used. As the delivery fiber 12, for example, a multimode fiber is used. As the movable stage 14, for example, a precision XY stage is used.

As shown in FIG. 1B, the processing head 13 includes a housing 130, a collimating lens 131, an axicon lens 133, a rotary lens holder 134, and a rotation mechanism 135. The collimating lens 131, the axicon lens 133, and the rotation mechanism 135 function as a beam shaper BS that forms a beam emitted from the delivery fiber 12 while converting it from a Gaussian beam G, G'to a Bessel beam B. The beam shaper BS is an aspect of the present invention.

The housing 130 is a tubular structure in which one end (upper end in FIG. 1) is closed and the other end (lower end in FIG. 1) is open. The delivery fiber 12 is drawn into the housing 130 through an insertion hole provided in the housing 130. The light emitted from the delivery fiber 12 becomes a Gaussian beam G that diverges (the beam diameter gradually increases along the optical path).

A collimating lens 131 is arranged on the optical path of the Gaussian beam G. The collimating lens 131 is a plano-convex collimating lens having a flat surface and a spherical convex surface. Collimator lens 131, the (collimator lens 131) flat surface, faces the exit surface of the delivery fiber 12, and, so as to be perpendicular to the center axis _{L 1} of the delivery fiber 12, the lens holder 132 of the housing 130 It is fixed to the inner surface. Central axis of the collimating lens 131 coincides with the center axis _{L 1} of the delivery fiber 12. The light emitted from the collimating lens 131 becomes a collimated Gaussian beam G'(with a constant beam diameter along the optical path). The central axis of the Gaussian beam G, G 'are consistent with each of the center axes of L ₁ and the collimator lens 131 of the delivery fiber 12. Therefore, the central axis L ₁ is also the central axis of the delivery fiber 12 and the central axis of the collimating lens 131.

An axicon lens 133 is arranged on the optical path of the Gaussian beam G'. The axicon lens 133 is a plano-convex axicon lens including a flat first end surface 133a and a conical second end surface 133b.

In the following, the normal of the first end face 133a through the apex of the second end face 133b and the spindle _{L 2.}

Axicon lens 133, held as the first end surface 133a is opposed to the spherical convex surface of the collimator lens 131, and, as the major axis L ₂ and the center axis L ₁ is shifted from each other, the interior of the rotary lens holder 134 Has been done. More particularly, Aki apex of the second end face 133b of the axicon lens 133 is located on the center axis L _1, so that the main axis L ₂ and the center axis L ₁ forms an inclination angle theta, the axicon lens 133 , It is held inside the rotary lens holder 134.

The rotary lens holder 134 includes, for example, an inner holder 134a fixed to the end surface (a portion forming a contour when viewed in a plan view) of the axicon lens 133, and an outer holder 134b fixed to the inner side surface of the housing 130. It can be configured by a bearing 134c interposed between the inner holder 134a and the outer holder 134b. The central axis of the inner holder 134a is disposed so as to coincide with the center axis L _1. Thus, the rotary lens holder 134, it is possible to rotate freely axicon lens 133 on the central axis L ₁ as the rotation axis. In this way, the axicon lens 133 is rotatably held on the inner surface of the housing 130 via the rotary lens holder 134.

The rotation mechanism 135 is a mechanism for rotating the axicon lens 133 via the inner holder 134a of the rotary lens holder 134. The rotation mechanism 135 can be composed of, for example, a shaft with a screw threaded to be screwed with the gear-shaped outer surface of the inner holder 134a, and a motor (not shown) for rotating the shaft.

The light emitted from the second end surface 133b of the axicon lens 133 becomes the Bessel beam B. As described above, since the main axis L ₂ and the central axis L ₁ form an inclination angle θ, the center of the vessel beam B is from the _{central axis L 1} in the direction corresponding to the _{inclination angle θ and the direction in which the main axis L 2 is inclined.} It is out of alignment. In FIG. 1 (b), the main shaft L ₂ is inclined from the center axis L ₁ in the y-axis positive side, as a result, the center of the Bessel beam B is shifted in the y-axis positive direction. Sonouede, by axicon lens 133 is rotated on the central axis L ₁ as the rotation axis, since the direction of the main axis L ₂ is tilted is rotated, the center of the Bessel beam B plane the central axis L ₁ and the normal line ( It moves while drawing a circular locus on the xy plane).

In addition, one aspect of the present invention includes a first end face having a planar shape and a second end face having a conical surface shape, and transmits the axicon lens 133 arranged on the optical path of the Gaussian beam G'. step of the generated Bessel beam B to a processing method of irradiating a workpiece W, rotation of the axicon lens 133 on the central axis L ₁ of the Gaussian beam G 'incident on the first end surface as a rotation axis by Processing methods including the above are also included. In the processing method according to one aspect of the present invention, the main shaft L ₂ and the central shaft L ₁ are deviated from each other.

(Intensity distribution of Bessel beam B)
The intensity distribution of the Bessel beam B will be described with reference to FIG. Each of (a), (b), and (c) of FIG. 2 shows a graph showing the intensity distribution of the Bessel beam B on the y-axis obtained by the processing apparatus 1, and the intensity of the Bessel beam B on the xy plane. It is a graph which shows the distribution. Each of FIG. 2 (a), (b) , and (c), respectively, are inclined to the y-axis negative direction side spindle _{L 2} from the center axis _{L 1,} and the inclination angle theta is, theta = The intensity distributions obtained at 0.1 degrees, 0.5 degrees, and 2 degrees are shown.

Of FIG. 2 (a), referring to each of (b), and (c), the larger the inclination angle θ is, the distance ΔP of the center of the center axis L ₁ and the Bessel beam B in the xy plane , You can see that it spreads. When the inclination angle θ is θ = 0.1 degrees, 0.5 degrees, and 2 degrees, the distances ΔP are ΔP = 0.002 mm, 0.009 mm, and 0.033 mm. Therefore, when the inclination angle θ is θ = 0.1 degrees, 0.5 degrees, and 2 degrees, the radius of the center of the Bessel beam B is approximately 0.002 mm by rotating the axicon lens 133. , 0.009 mm, 0.033 mm, moving while drawing a circular locus.

(Modification example of beam shaper BS)
The beam shaper BSA, which is a modification of the beam shaper BS, will be described with reference to FIGS. 3 and 4. FIG. 3 is a cross-sectional view showing the configuration of the beam shaper BSA. Each of (a), (b), and (c) of FIG. 4 shows a graph showing the intensity distribution of the vessel beam B on the y-axis obtained by the processing apparatus 1 equipped with the beam shaper BSA, and the vessel beam B. It is a graph which shows the intensity distribution on the xy plane. In each of (a), (b), and (c) of FIG. 4, the main axis L _2A is deviated from the central axis L ₁ to the positive / negative side of the y axis, and the distance ΔL described later is ΔL = 0. The intensity distributions obtained when the values are 1 mm, 0.2 mm, and 0.5 mm are shown.

The beam shaper BSA is obtained by replacing the axicon lens 133 with the axicon lens 133A as compared with the beam shaper BS shown in FIG. 1 (b).

The axicon lens 133A is a plano-convex axicon lens including a first end surface 133Aa on a plane and a second end surface 133Ab having a conical surface shape, similarly to the axicon lens 133. However, the shape of the axicon lens 133A is a normal line of the first end surface 133Aa through the apex of the second end surface 133Ab as spindle _{L 2A,} as the main axis _{L 2A} eccentrically from the center of the outer edge is circular It has been decided.

Like the axicon lens 133, the axicon lens 133A is rotatably held on the inner surface of the housing 130 via the inner holder 134a of the rotary lens holder 134. However, the axicon lens 133A is different from the axicon lens 133 in the way in which the spindle L _{2A deviates from the central axis L 1.} Axicon lens 133A is spindle _{L 2A} is parallel to the center axis _{L 1,} and, as the major axis _{L 2A} and the center axis _{L 1} are separated, are held inside the rotary lens holder 134 .. In other words, the axicon lens 133A is held in the interior of the rotary lens holder 134 in an eccentric state with respect to the center axis L _1. In the beam shaper BSA shown in FIG. 3, the spindle L _2A is separated from the central axis L ₁ by a distance ΔL on the positive side of the y-axis. The distance ΔL is preferably 0.1 mm or more. Further, the distance ΔL may be 0.2 mm or more, or 0.5 mm or more.

Since the main axis L _2A and the central axis L ₁ are separated from each other in this way, the center of the vessel beam B is the central axis L ₁ in the direction corresponding to the direction in which _{the main axis L 2A is separated from the central axis L 1.} It is out of alignment. In FIG. 3, the spindle L _2A is separated from the central axis L _{1 in the} positive direction of the y-axis, and as a result, the center of the Bessel beam B is displaced in the positive direction of the y-axis. Sonouede, by axicon lens 133A is rotated on the central axis L ₁ as the rotation axis, the direction of the main axis L _2A is separated from the center axis L ₁ is rotated. Therefore, the center of the Bessel beam B moves while drawing a circular locus on a plane (xy plane) having _{the central axis L 1A as a normal.}

Of FIG. 4 (a), referring to each of (b), and (c), the distance ΔL is the greater, the distance ΔP of the center of the center axis L ₁ and the Bessel beam B in the xy plane, You can see that it spreads. When the distance ΔL is ΔL = 0.1 mm, 0.2 mm, and 0.5 mm, the distance ΔP is ΔP = 0.1 mm, 0.2 mm, and 0.5 mm. Therefore, when the distance ΔL is ΔL = 0.1 mm, 0.2 mm, and 0.5 mm, the radii of the center of the Bessel beam B are approximately 0.1 mm and 0, respectively, by rotating the axicon lens 133A. . Move while drawing a circular locus of 2 mm and 0.5 mm.

[Additional notes]
The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims, and the embodiments obtained by appropriately combining the technical means disclosed in the different embodiments. Is also included in the technical scope of the present invention.

1 Processing equipment 11 Laser light source 12 _{Deliverable fiber L 1} Central axis BS Beam shaper G, G'Gaussian beam B Bessel beam 13 Processing head 130 Housing 131 Collimated lens 133 Axicon lens 133a First end face 133b Second end face L ₂ , L _2A Spindle 134 Rotating Lens Holder 135 Rotating Mechanism

Claims (6)

An axicon lens that includes a first end face that is planar and a second end face that is conical and is arranged on the optical path of the Gaussian beam.
A rotation mechanism for rotating the axicon lens with the central axis of the Gaussian beam incident on the first end face as a rotation axis is provided.
The main axis and the central axis are deviated from each other with the normal of the first end face passing through the apex of the second end face as the main axis.
A beam shaper that features that. The spindle is tilted with respect to the central axis.
The beam shaper according to claim 1. The main axis is parallel to the central axis and is separated from the central axis.
The beam shaper according to claim 1 or 2. The spindle is separated from the central axis by 0.1 mm or more.
The beam shaper according to claim 3. A processing head including the beam shaper according to any one of claims 1 to 4 is provided, and a Bessel beam output from the beam shaper is applied to the work.
A processing device characterized by this. The work is irradiated with a Bessel beam generated by passing through an axicon lens arranged on the optical path of the Gaussian beam, including a first end face having a flat surface and a second end face having a conical surface. It ’s a processing method,
A step of rotating the axicon lens with the central axis of the Gaussian beam incident on the first end face as a rotation axis is included.
The main axis and the central axis are deviated from each other with the normal of the first end face passing through the apex of the second end face as the main axis.
A processing method characterized by that.

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