JP2021142546A - Optical unit, laser beam machining apparatus and laser beam machining method - Google Patents

Abstract

To provide an optical unit having a narrow range in which a dead angle is formed with respect to irradiation angle of laser for an object to be worked, to provide a laser beam machining apparatus using the optical unit and to provide a laser beam machining method using them.SOLUTION: An optical unit is composed of a composite lens 1 and a reflection mirror 2. The composite lens 1 consists of an aspheric lens 3 and a mirror glass part 4. Light made incident to the aspheric lens 3 converges to a focal point P. On the other hand, reflected light, of light irradiated to the mirror glass part 4 is further reflected by the reflection mirror 2 and converges to the focal point P which is the same with the aspheric lens 3. Transmitted light, of light irradiated to the mirror glass 4 converges to the same focal point P with the aspheric lens 3.SELECTED DRAWING: Figure 6

Description

The present invention relates to an optical unit, a laser processing apparatus using the optical unit, and a laser processing method using the same.

At manufacturing sites that directly process metals and resins, ultrashort pulse lasers (picosecond lasers and femtosecond lasers) are used as a processing method that efficiently performs processing with no burrs and a high aspect ratio (depth / hole ratio). It is becoming the mainstream of law.

In laser machining, not only machining that narrows the machining area from the incident side to the back (that is, "forward taper machining"), but also machining that expands the machining area from the incident side to the back (that is, "reverse taper machining"). ”) Technology is also required. The reason is that if the performance of the device that changes the laser irradiation angle is improved and reverse taper processing becomes possible with a short pulse laser, three-dimensional to metal, resin, etc., which was not possible in the past, is possible. This is because high-speed direct processing is possible.
However, when reverse taper processing is performed using a laser, the laser beam must be controlled so as to be greatly inclined from the optical axis, and the difficulty of the control has been a problem.

In order to solve this problem, a technique has been developed in which a laser beam is reflected by a reflective objective lens of a Schwarzschild optical system to perform reverse taper processing (Patent Document 1). In this laser processing method, as shown in FIG. 1, a rotating laser beam X can be applied to the cone mirror 100, and the reflected beam can be reflected by the reflecting mirror 101 to irradiate the workpiece 102. Therefore, for example, as shown in FIG. 2, if the laser beam is operated by a polygon mirror or a galvano mirror, or the table on which the workpiece 102 is placed is moved in the xy direction, reverse taper processing can be performed. can.

However, in the reverse taper processing in which the laser beam described in Patent Document 1 is reflected by the reflection objective lens of the Schwarzschild optical system, the irradiation angle of the beam on the workpiece (the “irradiation angle” in the present specification is defined as the irradiation angle). In the angle formed by the incident direction and the normal of the boundary surface when light is incident), there is a problem that a blind spot θ is generated in a low angle region because the cone mirror 100 itself blocks the optical path (Fig.). 1).

JP-A-2017-71134

The present invention has been made in view of the above-mentioned conventional circumstances, and when used for laser machining on a workpiece, an optical unit having no blind spot between an irradiation angle of 0 degrees and an irradiation maximum angle is possible. It is an issue to be solved to provide a laser processing apparatus using the above and a laser processing method using them.

In order to solve the above-mentioned conventional problems, the present inventors have newly conceived and earnestly conceived a hybrid type optical unit in which an optical unit using a reflecting mirror is compounded on the periphery of an optical unit using an aspherical lens. As a result of conducting research, the present invention has been completed.

That is, the optical unit of the first invention includes a composite lens provided with an aspherical lens and a mirror glass portion provided on the periphery of the aspherical lens to reflect a part of incident light and transmit a part of the incident light. It is characterized by including a reflecting mirror installed so as to surround the periphery of the composite lens.

When the optical unit of the first invention is irradiated with a laser beam, the light emitted to the aspherical lens is focused on one point. Further, among the light irradiated to the mirror glass portion, the reflected light is further reflected by the reflecting mirror and focused on one point. In addition, the transmitted light among the light emitted to the mirror glass portion is also focused on one point.
Therefore, when this optical unit is used for laser machining on a work piece, it is possible to eliminate the blind spot between the irradiation angle of 0 degrees and the maximum irradiation angle. Therefore, for example, it can be designed to be controlled so as to be variable to an arbitrary angle in a range of 0 degrees or more and 45 degrees or less with respect to the central axis of the composite lens.

The optical unit of the second invention surrounds a composite lens provided with an aspherical lens, a mirror portion extending from the peripheral edge of the aspherical lens in the outward radial direction, and the periphery of the composite lens. It is characterized by being provided with a reflector installed in.

When the optical unit of the second invention is irradiated with a laser beam, among the light irradiated to the aspherical lens, the light not irradiated to the mirror portion is focused on one point. Further, among the light irradiated to the aspherical lens, the light reflected by the mirror glass is further reflected by the mirror unit and focused on one point, and the light transmitted through the mirror glass is also focused on one point. Further, the light reflected by the mirror unit is reflected by the reflecting mirror and focused on one point.
Therefore, when this optical unit is used for laser machining on a work piece, it is possible to eliminate the blind spot between the irradiation angle of 0 degrees and the maximum irradiation angle. Therefore, for example, it can be designed to be controlled so as to be variable to an arbitrary angle in a range of 0 degrees or more and 45 degrees or less with respect to the central axis of the composite lens.

The laser processing apparatus of the first invention is characterized by including the optical unit of the first invention or the second invention and a pulse oscillating laser.
If laser machining is performed using a pulse oscillation laser as a light source, the thermal effect of the workpiece can be reduced. Therefore, by combining this with the optical unit of the first invention or the second invention, precise machining including reverse taper machining with no blind spot between the irradiation angle of 0 degrees and the maximum irradiation angle can be performed. It will be possible.

The laser processing apparatus of the second invention is the laser processing apparatus of the first invention, and is characterized by including a beam rotation mechanism for controllingly rotating the radius of gyration of the beam emitted from the laser.
In the laser processing apparatus of the second invention, the irradiation angle of the laser can be easily controlled by controlling the radius of gyration of the beam emitted from the laser by the beam rotation mechanism.

The laser processing method of the first invention includes a first step of rotating the light emitted from the pulse-oscillating laser so that the radius of gyration can be controlled, and a second step of condensing the rotating beam into one point.
In the second step, a beam having a predetermined radius of gyration of the rotating beam is focused at one point through the aspherical lens, and a beam having a radius of gyration or more than the predetermined radius of the rotating beam is focused on the non-spherical lens. A part is reflected and a part is transmitted by a mirror glass portion provided on the periphery of the spherical lens, and the light reflected by the mirror glass portion is reflected by a reflecting mirror installed so as to surround the periphery of the composite lens. It is characterized in that the light transmitted through the mirror glass portion is focused on one point while being focused on one point.

In the laser processing method of the first invention, among the rotating beams, a beam having a radius of gyration less than a predetermined radius passes through the aspherical lens and is focused on one point. On the other hand, among the rotating beams, a beam having a predetermined radius of gyration or more is reflected and transmitted by a mirror glass portion provided on the peripheral edge of the aspherical lens. Then, the light reflected by the mirror glass portion is focused on one point, and the light transmitted through the mirror glass portion is also focused on one point. Therefore, precise machining including reverse taper machining with no blind spot between the irradiation angle of 0 degree and the maximum irradiation angle is possible.

The laser processing method of the second invention includes a first step of rotating the light emitted from the pulse-oscillating laser so that the radius of gyration can be controlled, and a second step of condensing the rotating beam at one point.
The second step is
The rotating beam is applied to the aspherical lens and the composite lens including the mirror portion extending from the peripheral edge of the aspherical lens while expanding the diameter in the outward direction.
A beam having a predetermined radius of gyration or more that has passed through the aspherical lens is partially reflected by a mirror glass portion provided on the emission light side of the aspherical lens, partially transmitted, and the light reflected by the mirror glass portion. Is reflected by a reflecting mirror installed so as to surround the periphery of the composite lens and focused on one point, and the light transmitted through the mirror glass portion is focused on one point.
The feature is that the light reflected by the mirror portion is reflected by a reflecting mirror installed so as to surround the periphery of the composite lens and focused on one point.

In the laser processing method of the second invention, the rotating beam is applied to the aspherical lens and the composite lens including the mirror portion extending from the peripheral edge of the aspherical lens while expanding the diameter in the outer diameter direction. Then, a beam having a predetermined radius of gyration or more that has passed through the aspherical lens is partially reflected by the mirror glass portion provided on the emitted light side of the aspherical lens, and a part is transmitted. Further, the light reflected by the mirror glass portion is reflected by a reflecting mirror installed so as to surround the periphery of the composite lens and is focused on one point. Further, the light transmitted through the mirror glass portion is also focused on one point. Further, the light reflected by the mirror portion is reflected by a reflecting mirror installed so as to surround the periphery of the composite lens and is focused on one point. Therefore, precise machining including reverse taper machining with no blind spot between the irradiation angle of 0 degree and the maximum irradiation angle is possible.

7, 11 ... Optical unit 1, 12 ... Composite lens 3, 14 ... Aspherical lens 4, 15 ... Mirror part (15a ... front surface, 15b ... back surface)
16 ... Reflective part (16a ... Transmitting part, 16b ... Mirror glass)
2, 13 ... Reflector 5 ... Laser 6 ... Beam rotator (beam rotation mechanism)
Hollow motor ... 8,9, wedge board ... 8a, 9a
10 ... Work piece

It is a schematic diagram which shows the laser processing apparatus using the conventional Schwarzschild optical system. It is a schematic cross-sectional view at the time of processing the workpiece by the laser processing method using the conventional Schwarzschild optical system. It is a schematic diagram of the experimental apparatus for irradiating an aspherical lens with a rotating laser beam. It is a schematic diagram of the conventional laser processing apparatus using the optical unit which combined the cone mirror and the parabolic mirror. This is an experimental device for investigating the relationship between the radius of gyration of a laser beam and the irradiation angle of a laser beam. It is a schematic diagram of the optical unit of Embodiment 1. It is a schematic diagram of the laser processing apparatus using the optical unit of Embodiment 1. It is a schematic diagram which showed the optical path of the optical unit of Embodiment 2.

Hereinafter, embodiments embodying the present invention will be described. However, the present invention is not limited to this embodiment. Various modifications are also included in the present invention as long as they do not deviate from the claims and can be easily conceived by those skilled in the art.

<Optical unit>
-Laser processing with an aspherical lens As a preparation for designing the optical unit of the present invention, as shown in FIG. 3, the laser beam is rotated by a beam rotator with a radius of gyration R, and the rotating laser beam is non-focal distance f. The irradiation angle θ when the spherical lens was irradiated was calculated. The results are shown in Table 1.

The irradiation angle is proportional to the radius of gyration and the focal length is inversely proportional. As shown in Table 1, for example, when the turning radius is 20 mm and the focal length is 40 mm, the irradiation angle is 26.564 degrees. By adjusting the radius of gyration in this way, it is possible to realize an irradiation angle that was not possible until now.

-Optical unit combining a cone mirror and a parabolic mirror The following test is performed on a laser processing device using an optical unit combining a cone mirror and a parabolic mirror as described in Patent Document 1. went.
In this laser processing device, as shown in FIG. 4, a laser beam is rotated by a beam rotator, the rotating laser beam is irradiated to a cone mirror and reflected, and a parabolic mirror is arranged so as to surround the cone mirror. It is reflected by a surface mirror and focused on the focal point.

Using the test device shown in FIG. 5, the relationship between the radius of gyration R of the laser beam irradiated to the cone mirror in this laser processing device and the irradiation angle θ of the laser beam reflected by the parabolic mirror and irradiated is measured. bottom.
That is, the laser beam was irradiated from a semiconductor laser light source, reflected by a reflector at an angle of 90 degrees, reflected by a parabolic mirror with a focal length (F) of 600 mm, and focused on one point. At this time, the optical axis of the semiconductor laser was changed in the horizontal range of 0 to 13 mm.

As a result, it was found that the irradiation angle of the laser beam after being reflected by the parabolic mirror changes in the range of 43.5 degrees to 45 degrees.

(Embodiment 1)
As shown in FIG. 6, the optical unit of the first embodiment includes a composite lens 1 and a reflecting mirror 2 installed so as to surround the periphery of the composite lens 1. The composite lens 1 includes an aspherical lens 3 and a mirror glass portion 4 provided on the peripheral edge of the aspherical lens 3. In FIG. 6, the dotted line shows the optical path when the laser beam is irradiated. The mirror glass portion 4 reflects a part of the incident light at a predetermined ratio and transmits a part of the incident light. Of the light incident on the composite lens 1, the light incident on the aspherical lens 3 is focused on the focal point P according to the focal length (first optical path). Further, among the light emitted to the mirror glass portion 4, the reflected light is further reflected by the reflecting mirror 2 and focused on the same focal point P as the aspherical lens 3 (second optical path). Of the light emitted to the mirror glass portion 4, the transmitted light is focused on the same focal point P as the aspherical lens 3 (third optical path). Further, when the light reflected on the outermost side of the mirror glass portion 4 is reflected by the reflecting mirror 2 and focused on the focal point P, the irradiation angle is set to 45 degrees.

When the optical unit of the first embodiment configured as described above is irradiated with a laser beam, the light emitted to the aspherical lens 3 is focused on the focal point P ( _{range of θ 1} in FIG. 6). Further, a part of the light irradiated to the mirror glass portion 4 is reflected, further reflected by the reflecting mirror 2, and focused on the focal point P ( _{range of θ 2} in FIG. 6). Further, of the light irradiated to the mirror glass portion 4, the transmitted light is focused on the focal point P ( _{range of θ 3} in FIG. 6). Therefore, there is no blind spot in the range of 0 degrees or more and 45 degrees or less with respect to the central axis of the composite lens 1.

(Modified Example of Embodiment 1)
In the first embodiment, the first optical path, the second optical path, and the third optical path are all focused on the same focal point P, but are 0 degrees with respect to the central axis of the composite lens 1. The positions of the focal points may be different as long as there is no blind spot in the range of 45 degrees or more. Even in this case, by controlling the movement of a stage (not shown) on which the non-processed object 10 is placed, it is possible to focus the light on the irradiation position of the non-processed object 10 of the laser processing apparatus. It can be used as an optical unit.

Further, when a reflecting mirror that does not transmit light is used instead of the mirror glass portion 4 in the optical unit of the first embodiment, only the angle range of θ3 in FIG. 6 becomes a blind spot, but the irradiation angle reaches the range of θ2. Can have the effect of being able to increase.

A laser processing apparatus using the optical unit of the first embodiment is shown in FIG. This laser processing apparatus includes a laser 5, a beam rotator 6, and an optical unit 7. The beam rotator 6 is a beam rotation mechanism. As the laser 5, a laser that oscillates in a pulse is used in order to improve the processing accuracy. For example, a pulse oscillation laser using an excimer laser, an Nd: YAG laser, a semiconductor laser, a fiber laser, a CO2 laser or the like can be used. Depending on the material of the work piece, it can be appropriately selected in consideration of the wavelength, pulse width and the like. For example, in order to minimize thermal deformation, it is preferable to use a short pulse laser device such as a nanosecond pulse laser.

The beam rotator 6 has wedge substrates 8a and 9a built in the two hollow motors 8 and 9, respectively. The hollow motors 8 and 9 are synchronized, and by adjusting the synchronization relationship, it is possible to adjust the relative angle relationship between the wedge substrate 21a and the wedge substrate 22a around the axis. Further, the optical unit 7 is the optical unit of the first embodiment described above (see FIG. 6).

The beam adjusted to a predetermined radius of gyration from the beam rotator 6 is irradiated to the optical unit 7. When the radius of gyration of the beam does not hit the mirror glass portion 4, the beam is refracted by the aspherical lens 3 and focused on one point. On the other hand, when the radius of gyration of the beam hits the mirror glass portion 4, a part of the beam is reflected by the mirror glass portion 4, and the reflected beam is further arranged so as to surround the mirror glass portion 4. It is reflected by 2 and focused on one point. Further, a part of the beam irradiated to the mirror glass portion 4 is transmitted and focused on one point.

In the laser processing apparatus of the first embodiment configured as described above, the positional relationship of the angles around the axes of the wedge substrates 8a and 9a is adjusted by adjusting the synchronization relationship of the hollow motors 8 and 9 in the beam rotator 6. can do. Therefore, the beam emitted from the laser 5 can be rotated with an arbitrary radius of gyration while maintaining a parallel relationship with the axial direction of the beam emitted from the laser 5.

In this laser processing apparatus, if the laser 5 is driven while the beam rotator 6 controls the radius of gyration of the laser beam so as not to hit the mirror glass 4, the beam is refracted by the aspherical lens 3 and processed. The object 10 is irradiated. On the other hand, if the beam rotator 6 controls the radius of gyration of the laser beam so as to hit the mirror glass 4, a part of the beam is reflected by the mirror glass portion 4, and this reflected beam is further reflected by the reflecting mirror 2 to a single point. Condensing. Further, a part of the beam irradiated to the mirror glass portion 4 is transmitted and focused on one point. Therefore, it is possible to irradiate the laser in an arbitrary range of 0 degrees or more and 45 degrees or less with respect to the central axis of the composite lens 1, and there is no range that becomes a blind spot.

(Embodiment 2)
FIG. 8 is a schematic view of the optical unit 11 of the second embodiment, and is composed of a composite lens 12 and a reflector 13 arranged so as to surround the periphery of the composite lens 12. The composite lens 12 has an aspherical lens 14 provided at the upper end and a mirror portion 15 extending downward in diameter so as to project outward from the peripheral edge of the aspherical lens 14. There is. The front surface 15a and the back surface 15b of the mirror portion 15 are coated with a metal such as aluminum so that light can be reflected. A reflecting portion 16 is provided below the aspherical lens 14. The upper end portion of the reflecting portion 16 is flat and is a transmitting portion 16a through which light can be transmitted, and the peripheral portion is a mirror glass 16b. Of the laser beams incident on the aspherical lens 14, the light reflected by the mirror glass 16b is reflected by the back surface 15b of the mirror portion 15 and then focused on the focal point P. Further, among the laser beams incident on the aspherical lens 14, the light transmitted through the mirror glass 16b is focused on the focal point P. Further, among the laser beams incident on the aspherical lens 14, the light transmitted through the transmitting portion 16a is focused on the focal point P.

When the optical unit 11 of the second embodiment configured as described above is irradiated with the laser beam, the laser beam that reaches the transmitting portion 16a at the upper end portion of the reflecting portion 16 among the laser beams irradiated to the aspherical lens 14 is generated. , It is transmitted as it is and focused on the focal point P ( _{range of θ 4} in FIG. 8). Further, of the laser beam irradiated to the aspherical lens 14, a part of the laser beam reaching the mirror glass 16b at the peripheral portion of the reflecting portion 16 is reflected, and further reflected by the back surface 15b of the mirror portion 15 to be aspherical. Focuses on the same focal point P as the lens 14 ( _{range of θ 5} in FIG. 8). Further, the light transmitted through the mirror glass 16b on the peripheral portion of the reflecting portion 16 is focused on the focal point P. Further, of the laser beams irradiated to the composite lens 12, the laser beam irradiated to the surface 15a of the mirror portion 15 is reflected, and further totally reflected by the reflecting mirror 13 to be focused on the same focal point P as the aspherical lens 3. (range of theta ₆ in FIG. 6).
Therefore, when the optical unit 11 of the second embodiment is irradiated with a laser beam, it is possible to irradiate the laser beam in an arbitrary range of 0 degrees or more and 45 degrees or less with respect to the central axis of the composite lens 12, and there is a range of blind spots. do not.

Claims (9)

A composite lens provided with an aspherical lens and a mirror glass portion provided on the periphery of the aspherical lens to reflect a part of incident light and transmit a part of the incident light.
An optical unit including a reflecting mirror installed so as to surround the periphery of the composite lens. Of the light incident on the composite lens, the first optical path in which the light incident on the aspherical lens is focused on one point, and the light reflected by the mirror glass portion is further reflected by the reflecting mirror and focused on one point. The optical unit according to claim 1, further comprising a second optical path and a third optical path in which light transmitted through the mirror glass portion is focused at one point. A mirror glass that reflects a part of the incident light and transmits a part of the incident light is provided on the emitted light side of the aspherical lens, and the light reflected by the mirror glass is further reflected by the mirror portion and collected at one point. The optical unit according to claim 1 or 2, wherein the light that shines and passes through the mirror glass is focused at one point. An aspherical lens and a composite lens provided with a mirror portion extending from the peripheral edge of the aspherical lens while expanding the diameter in the outward direction.
An optical unit including a reflecting mirror installed so as to surround the periphery of the composite lens. Of the light incident on the composite lens, the first optical path in which the light incident on the aspherical lens is focused on one point, and the light reflected by the mirror portion is further reflected by the reflecting mirror and focused on one point. It has 2 light paths and
A mirror glass that reflects a part of the incident light and transmits a part of the incident light is provided on the emitted light side of the aspherical lens, and the light reflected by the mirror glass is further reflected by the mirror portion and collected at one point. The optical unit according to claim 4, further comprising light and condensing the light transmitted through the mirror glass at one point. A laser processing apparatus including the optical unit according to any one of claims 1 to 5 and a pulse oscillating laser. The laser processing apparatus according to claim 4, further comprising a beam rotation mechanism for controllingly rotating the radius of gyration of the beam emitted from the laser. It includes a first step of rotating the light emitted from the pulse-oscillating laser so that the radius of gyration can be controlled, and a second step of concentrating the rotating beam on one point.
The second step is
Of the rotating beams, a beam having a predetermined radius of gyration or less is focused at one point through an aspherical lens.
A part of the rotating beam having a radius of gyration or more is reflected by a mirror glass portion provided on the peripheral edge of the aspherical lens, a part of the beam is transmitted, and the light reflected by the mirror glass portion is reflected. A laser processing method characterized in that light transmitted through the mirror glass portion is focused on one point while being reflected by a reflecting mirror installed so as to surround the periphery of the composite lens and focused on one point. It includes a first step of rotating the light emitted from the pulse-oscillating laser so that the radius of gyration can be controlled, and a second step of concentrating the rotating beam at one point.
The second step is
The rotating beam is applied to the aspherical lens and the composite lens including the mirror portion extending from the peripheral edge of the aspherical lens while expanding the diameter in the outward direction.
A beam having a predetermined radius of gyration or more that has passed through the aspherical lens is partially reflected by a mirror glass portion provided on the emission light side of the aspherical lens, partially transmitted, and the light reflected by the mirror glass portion. Is reflected by a reflecting mirror installed so as to surround the periphery of the composite lens and focused on one point, and the light transmitted through the mirror glass portion is focused on one point.
A laser processing method characterized in that the light reflected by the mirror portion is reflected by a reflecting mirror installed so as to surround the periphery of the composite lens and focused on one point.

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