JP2020154087A - Laser beam shaping device - Google Patents

Abstract

To provide a laser beam shaping device capable of preventing power loss of a laser beam and a thermal damage of a component in the device and capable of efficiently irradiating a target with a laser beam having a desired cross-sectional shape.SOLUTION: A laser beam shaping device includes: a first optical system for separating a laser beam into a first beam shaped into a desired cross-sectional shape by deflecting a part of the laser beam and a second beam other than the first beam; and a second optical system which merges the second beam into a coaxial core shape with respect to the first beam.SELECTED DRAWING: Figure 1

Description

The present invention relates to a laser beam shaping apparatus.

Conventionally, an emitting device that irradiates a target located at a relatively distant place with a high-power laser beam has been known. In order to properly irradiate such a target with a laser beam, it may be required to efficiently and stably irradiate a laser beam having a desired cross-sectional shape.

As a method for obtaining a laser beam as described above, for example, as disclosed in Patent Document 1, a method for shaping a laser beam by cutting (clip) the cross-sectional peripheral edge of the laser beam with a limiting aperture (slit) is known. Has been done.

Japanese Unexamined Patent Publication No. 2013-233556

However, in the above method, power loss occurs due to the cutting of the laser beam. Further, when the laser beam hits a component other than the optical system in the emitting device, the component may be thermally damaged.

Therefore, it is an object of the present invention to prevent power loss of the laser beam and thermal damage of parts in the emitting device, and to make it possible to efficiently irradiate the target with the laser beam having a desired cross-sectional shape.

In order to solve the above problems, the laser beam shaping apparatus according to one aspect of the present invention has a first beam in which the laser beam is shaped into a desired cross-sectional shape by deflecting a part of the laser beam and the first beam. It includes a first optical system that separates the second beam from other than the second beam, and a second optical system that joins the second beam coaxially with the first beam.

According to the above configuration, a laser beam having a desired cross-sectional shape can be obtained by shaping the laser beam with the first optical system. Further, since the laser beam is shaped by deflecting a part of the laser beam by the first optical system, it is possible to prevent parts other than the optical system in the apparatus from hitting the laser beam when shaping the laser beam. It can prevent thermal damage. As a result, the device can be driven stably.

Further, the second beam, which is deflected by the first optical system and separated from the first beam, is coaxially merged with the first beam by the second optical system. Therefore, it is possible to prevent power loss from occurring when shaping the laser beam. Therefore, the target can be efficiently irradiated with a laser beam shaped so as to have a desired cross-sectional shape.

The second beam may be an outer peripheral portion of the laser beam, and the first beam may be a central portion located inside the outer peripheral portion of the laser beam.

Thereby, for example, even when the intensity distribution of the laser beam is a normal distribution or the like, it is possible to easily increase the power of the emitted laser beam while preventing power loss and thermal damage. Further, for example, by increasing the emission aperture at which the laser beam is emitted, the intensity and focusing intensity of the laser beam at the irradiation position of the target can be increased.

The second optical system is arranged by arranging the second beam coaxially with respect to the first beam and surrounding the outside, and reducing the diameter toward the downstream side in the light guide direction. It may be merged with the first beam. This makes it possible to further increase the intensity and focusing intensity of the laser beam at the irradiation position of the target.

The first optical system is a downstream scraper mirror having an annular reflecting surface that allows the central portion of the laser beam to pass as the first beam and reflects the outer peripheral portion of the laser beam as the second beam. The reflective surface of the downstream scraper mirror may be arranged so as to be inclined with respect to the optical axis of the first beam. As a result, the first beam and the second beam can be separated relatively easily while simplifying the structure of the optical system.

The second optical system is an annular reflection that allows the laser beam to pass upstream of the downstream scraper mirror and merges the second beam reflected by the downstream scraper mirror with the first beam. It may have an upstream scraper mirror with a surface. As a result, the outer peripheral portion of the laser beam can be easily merged with the central portion while simplifying the structure of the optical system.

The laser beam guided upstream of the first optical system is an annular laser beam having an annular cross section, and the second beam is an outer peripheral portion of the annular laser beam and the outer peripheral portion. An inner peripheral portion located inside the portion, and the first beam is an intermediate peripheral portion located between the inner peripheral portion and the outer peripheral portion of the annular laser beam, and is the first optical system. May individually have a first mirror that reflects the outer peripheral portion of the annular laser beam and a second mirror that reflects the inner peripheral portion of the annular laser beam.

The laser beam guided upstream of the first optical system is an annular laser beam having an annular cross section, and the first beam is an outer peripheral portion of the annular laser beam. The second beam is an inner peripheral portion located inside the outer peripheral portion of the annular laser beam, and the second optical system makes the second beam coaxial with the first beam. It may be merged with the first beam by arranging the laser so as to surround the outer side and reducing the diameter toward the downstream side in the light guide direction.

The laser beam guided upstream of the first optical system may be an annular laser beam having an annular cross section.

The second optical system may have at least one of an axicon lens and an axicon mirror. Thereby, even when the second beam is an annular laser beam, the second beam can be satisfactorily merged with the first beam.

The second optical system may have at least one of a convex lens, a concave lens, a spherical mirror, and a parabolic mirror. By using such a relatively versatile optical system component, a laser beam shaping apparatus can be constructed at a relatively low cost.

The second optical system performs the second beam a plurality of times between a separation position for separating the first beam and the second beam and a merging position for merging the second beam with the first beam. It may be circulated.

According to the above configuration, when the second beam is merged with the first beam, the inclination angle of the second beam with respect to the optical axis of the first beam can be made gentle to improve the focusing property of the laser beam.

According to each aspect of the present invention, it is possible to prevent power loss of the laser beam and thermal damage of parts in the emitting device, and to efficiently irradiate the target with the laser beam having a desired cross-sectional shape.

It is a schematic diagram of the laser beam shaping apparatus which concerns on 1st Embodiment. It is a figure which shows the partial structure of the 1st optical system of FIG. 1 and the structure around it. It is a figure which shows the structure of the scraper mirror on the upstream side of FIG. 1 and its periphery. It is a figure which shows the partial structure of the 2nd optical system of FIG. It is a figure which shows the cross-sectional shape of the laser beam of FIG. It is a figure which shows the intensity distribution of the laser beam of FIG. It is a figure which shows the partial structure of the 2nd optical system which concerns on the modification of 1st Embodiment. It is a schematic diagram of the laser beam shaping apparatus which concerns on 2nd Embodiment. It is a figure which shows the cross-sectional shape of the laser beam of FIG. It is a figure which shows the intensity distribution of the laser beam of FIG. It is a schematic diagram of the laser beam shaping apparatus which concerns on 3rd Embodiment. It is a figure which shows the cross-sectional shape of the laser beam of FIG. It is a figure which shows the partial structure of the 2nd optical system of FIG. It is a figure which shows the partial structure of the 2nd optical system which concerns on the modification of 3rd Embodiment. It is a schematic diagram of the laser beam shaping apparatus which concerns on 4th Embodiment.

Hereinafter, each embodiment will be described with reference to the drawings. In the following description, the upstream side refers to the upstream side in the light guide direction of the laser beam, and the downstream side refers to the downstream side in the light guide direction.

(First Embodiment)
FIG. 1 is a schematic view of a laser beam shaping device 1 (hereinafter, also referred to as a shaping device 1) according to the first embodiment. FIG. 2 is a diagram showing a partial configuration of the first optical system 2 of FIG. 1 and its peripheral configuration. FIG. 3 is a diagram showing the configuration of the upstream scraper mirror 34 of FIG. 1 and its periphery. FIG. 4 is a diagram showing a partial configuration of the second optical system 3 of FIG. FIG. 5 is a diagram showing a cross-sectional shape of the laser beam L1 of FIG.

As shown in FIGS. 1 to 3, the shaping device 1 shapes the laser beam L1 output from the laser beam oscillating device 10. The shaping device 1 includes a first optical system 2 and a second optical system 3. The first optical system 2 and the second optical system 3 are arranged on the optical path of the laser beam L1 in the shaping device 1. As shown in FIG. 5, the laser beam L1 has a circular cross-sectional peripheral edge as an example, and is formed solidly.

The laser beam L1 of the present embodiment has an outer peripheral portion 80 and a central portion 81 located inside the outer peripheral portion 80. The outer peripheral portion 80 has an annular cross section, and the central portion 81 has a circular cross section. The outer peripheral portion 80 and the central portion 81 are continuous. In the shaping device 1, in order to shape the laser beam L1 into a desired cross-sectional shape, a portion removed from the laser beam L1 is designated as an outer peripheral portion 80, and a portion to be retained is designated as a central portion 81.

The first optical system 2 separates the laser beam L1 into a first beam B1 shaped into a desired cross-sectional shape and a second beam B2 other than the first beam B1 by deflecting a part of the laser beam L1. The first optical system 2 of the present embodiment includes guide mirrors 21 and 22, a downstream scraper mirror 23, and a guide mirror 24. The mirrors 21 to 24 are arranged apart from each other in the same order in the light guide direction of the laser beam L1.

The guide mirrors 21, 22, and 24 guide the laser beam L1 to a predetermined optical path. The downstream scraper mirror 23 has an annular reflecting surface 23a and a through hole 23b. The reflecting surface 23a reflects the outer peripheral portion 80 of the laser beam L1 as the second beam B2. The reflecting surface 23a is arranged so as to be inclined with respect to the optical axis of the first beam B1 (laser beam L1). That is, the first optical system 2 of the present embodiment deflects a part of the laser beam L1 by reflection. The through hole 23b allows the central portion 81 of the laser beam L1 to pass through as the first beam B1.

The first beam B1 passes through the through hole 23b of the downstream scraper mirror 23. The inclination angle of the reflecting surface 23a with respect to the optical axis of the first beam B1 (laser beam L1) can be appropriately set.

As described above, in the present embodiment, the second beam B2 is the outer peripheral portion 80 of the laser beam L1, and the first beam B1 is the central portion 81 of the laser beam L1.

The second optical system 3 joins the second beam B2 coaxially with the first beam B1. The second optical system 3 of the present embodiment has at least one of a convex lens, a concave lens, a spherical mirror, and a parabolic mirror. As an example, the second optical system 3 has convex lenses 31, 32, a guide mirror 33, and an upstream scraper mirror 34.

The convex lenses 31 and 32 and the guide mirror 33 guide the second beam B2 deflected by the first optical system 2 to a predetermined optical path. As shown in FIG. 4, the convex lenses 31 and 32 are arranged apart from each other with a distance D1 between the lenses. The focal length F1 of the convex lens 31 and the focal length F2 of the convex lens 32 are both larger than 0. Here, by setting the inter-lens distance D1 to be larger than the total focal length (F1 + F2), the convex lenses 31 and 32 focus the second beam B2. After setting D1 = F1 + F2 to make the second beam parallel once, the second beam reflected by the upstream scraper mirror 34 as a concave parabolic mirror may be focused. The upstream scraper mirror 34 is basically a flat mirror, but may be a parabolic mirror. When the upstream scraper mirror 34 is a parabolic mirror, the parallel incident beam incident on the upstream scraper mirror 34 is converted into a focused reflected beam.

The second optical system 3 of the present embodiment uses a magnifying optical system having convex lenses 31 and 32, so that the second optical system 3 retains the cross-sectional shape of the second beam B2 (including the shape such as the outer diameter / inner diameter ratio). The outer diameter of the 2-beam B2 can be changed (enlarged). A concave lens having a focal length smaller than 0 may be used instead of the convex lens 31.

The upstream scraper mirror 34 shown in FIG. 1 has an annular reflecting surface 34a and a through hole 34b. The reflecting surface 34a merges the second beam B2 reflected by the downstream scraper mirror 23 with the first beam B1. The through hole 34b allows the laser beam L1 to pass on the upstream side of the downstream scraper mirror 23.

The holding member for holding each mirror can be appropriately selected. When the holding member is arranged so as to straddle the optical path of the laser beam L1, the area of the surface of the holding member perpendicular to the traveling direction of the laser beam L1 is adjusted to be reduced as much as possible.

When the shaping device 1 is driven, the laser beam L1 is guided by the guide mirror 21 from the upstream side to the downstream side in the light guide direction of the laser beam L1, and then passes through the through hole 34b of the upstream scraper mirror 34. The guide mirror 22 guides the scraper mirror 23 on the downstream side.

In the downstream scraper mirror 23, the laser beam L1 is separated into a first beam B1 that passes through the through hole 23b of the downstream scraper mirror 23 and a second beam B2 that is reflected by the reflection surface 23a.

After passing through the through hole 23b of the downstream scraper mirror 23, the first beam B1 is guided by the guide mirror 24 and introduced into the emission optical system (here, the emission device 40) as the emission laser beam L2. The cross section shown at the right end of the drawing of FIG. 2 shows a schematic circular cross section of the emitted laser beam L2.

On the other hand, as shown in FIG. 2, the second beam B2 reflected by the downstream scraper mirror 23 is guided by the convex lenses 31 and 32, then reflected by the guide mirror 33 and guided by the upstream scraper mirror 34. To. At this time, the second beam B2 is focused by the convex lens 32. After that, as shown in FIG. 3, the second beam B2 is reflected by the reflecting surface 34a of the upstream scraper mirror 34 and merges with the first beam B1.

At the time of this merging, the second optical system 3 arranges the second beam B2 coaxially with respect to the first beam B1 so as to surround the outside, and reduces the diameter toward the downstream side in the light guide direction. By letting it join the first beam B1. The emission laser beam L2 is formed by merging the first beam B1 and the second beam B2.

Here, in the present embodiment, at the confluence position of the laser beam L1 and the second beam B2 on the reflection surface 34a, the inner diameter of the second beam B2 is the laser beam L1 that has passed through the through hole 34b of the upstream scraper mirror 34. It is sufficiently larger than the outer diameter. As an example, the inner circumference of the second beam B2 at the confluence position is radially separated from the outer circumference of the laser beam L1 that has passed through the upstream scraper mirror 34. From this state, the second beam B2 is guided together with the laser beam L1 and merges with the first beam B1 while being focused toward the axis of the first beam B1 which is the central portion 81 of the laser beam L1.

When the merged first beam B1 and second beam B2 pass through the through hole 23b of the downstream scraper mirror 23, all of them may pass at once, or they may pass through the optical path in the shaping device 1 a plurality of times. It may pass while circulating. In the present embodiment, the second optical system 3 has a second position between the separation position for separating the first beam B1 and the second beam B2 and the merging position for merging the second beam B2 with the first beam B1. The beam B2 is circulated a plurality of times.

FIG. 6 is a diagram showing the intensity distribution of the laser beam L1 of FIG. As shown in FIG. 6, the intensity distribution of the laser beam L1 of the present embodiment is a normal distribution. If the outer peripheral portion 80 of the laser beam L1 is simply cut by the limiting aperture to shape the laser beam L1, the power loss of the laser beam L1 corresponding to the cut portion (the portion shown by the broken line in the graph of FIG. 6). Occurs.

On the other hand, in the shaping device 1, since the cut portion (second beam B2) of the laser beam L1 generated when the laser beam L1 is shaped is merged with the first beam B1, power loss is prevented.

As described above, according to the shaping device 1, the laser beam L1 having a desired cross-sectional shape can be obtained by shaping the laser beam L1 by the first optical system 2. Further, since the laser beam L1 is shaped by deflecting a part of the laser beam L1 by the first optical system 2, parts other than the optical system in the shaping device 1 hit the laser beam L1 when shaping the laser beam L1. Since it can be prevented, it is possible to prevent the component from being thermally damaged. As a result, the shaping device 1 can be driven stably.

Further, the second beam B2, which is deflected by the first optical system 2 and separated from the first beam B1, is joined by the second optical system 3 in a coaxial center shape with respect to the first beam B1. Therefore, it is possible to prevent power loss from occurring when shaping the laser beam L1. Therefore, the target can be efficiently irradiated with a laser beam shaped so as to have a desired cross-sectional shape.

Here, conventionally, in order to appropriately irradiate a small target located far from the emitting device, it is required to increase the intensity of the laser beam and the focusing performance of the laser beam, for example.

As for the laser beam, the larger the beam diameter at the time of emission (hereinafter, referred to as “emission beam diameter”), the better the focusing performance and intensity at the irradiation position of the target. Therefore, the larger the emitted beam diameter, the better. On the other hand, if the emission beam diameter is larger than the emission aperture of the emission device, the laser beam may hit a component other than the optical system in the emission device, causing thermal damage to the component or thermal influence on the emission device.

As a countermeasure for this problem, first, there is a method of reducing the emission beam diameter. Secondly, a method is conceivable in which the peripheral edge of the cross section of the emitted beam is cut by a limiting aperture to shape the laser so that the laser does not hit the component.

However, in the first method, it may be difficult to obtain sufficient focusing performance and intensity of the laser beam at the irradiation position of the target. In addition, power loss occurs in the second method. This power loss usually increases as the emission beam diameter is increased in order to improve the focusing performance.

On the other hand, according to the shaping device 1, the laser beam L1 is shaped by removing the outer peripheral portion 80 as the second beam B2 from the laser beam L1, so that the diameter of the laser beam L1 is changed to obtain the emitted beam diameter. Since it can be adjusted to the value of, the focusing performance and intensity of the laser beam at the irradiation position of the target can be improved.

Further, by merging the first beam B1 and the second beam B2 separated by the first optical system 2, it is possible to prevent power loss from occurring even if the emission beam diameter is greatly adjusted. Further, by using the first optical system 2, the above-mentioned thermal damage and thermal influence can be prevented.

Further, since the second beam B2 is the outer peripheral portion 80 and the first beam B1 is the central portion 81, for example, even when the intensity distribution of the laser beam L1 is a normal distribution or the like, power loss and thermal damage can be prevented. The power of the emitted laser beam L2 can be easily increased. Further, for example, by increasing the emission aperture at which the laser beam is emitted, the intensity and focusing intensity of the laser beam at the irradiation position of the target can be increased.

Further, the second optical system 3 arranges the second beam B2 coaxially with respect to the first beam B1 so as to surround the outside, and reduces the diameter toward the downstream side in the light guide direction. Since it merges with the first beam B1, the intensity and focusing intensity of the laser beam at the irradiation position of the target can be further increased.

Further, the first optical system 2 has an annular reflecting surface 23a that allows the central portion 81 of the laser beam L1 to pass as the first beam B1 and reflects the outer peripheral portion 80 of the laser beam L1 as the second beam B2. It has a scraper mirror 23, and the reflecting surface 23a is arranged so as to be inclined with respect to the optical axis of the first beam B1. As a result, the first beam B1 and the second beam B2 can be separated relatively easily while simplifying the structure of the optical system.

Further, the second optical system 3 passes the laser beam L1 on the upstream side of the downstream scraper mirror 23, and guides the second beam B2 reflected by the downstream scraper mirror 23 together with the laser beam L1. It has an upstream scraper mirror 34 having an annular reflecting surface 34a that merges with one beam B1. As a result, the outer peripheral portion 80 of the laser beam L1 can be easily merged with the central portion 81 while simplifying the structure of the optical system.

Further, the second optical system 3 has a plurality of second beams B2 between the separation position for separating the first beam B1 and the second beam B2 and the merging position for merging the second beam B2 with the first beam B1. Circulate around. By doing so, when the second beam B2 is merged with the first beam B1, the inclination angle of the second beam B2 with respect to the optical axis of the first beam B1 is made gentle, and the focusing property of the laser beam is improved. be able to.

The second optical system 3 has at least one of a convex lens, a concave lens, a spherical mirror, and a parabolic mirror. By using such a relatively versatile optical system component, the shaping apparatus 1 can be configured at a relatively low cost.

FIG. 7 is a diagram showing a partial configuration of a second optical system according to a modified example of the first embodiment. This second optical system has a concave mirror 35 instead of the convex lens 31 and a concave mirror 36 instead of the convex lens 32. The focal length F3 of the concave mirror 35 and the focal length F4 of the concave mirror 36 are both larger than 0. By setting the inter-mirror distance D2 larger than the total focal length (F1 + F2), the concave mirrors 35 and 36 are arranged so as to focus the second beam B2.

In the above configuration, the second beam B2 separated by the first optical system is reflected by the concave mirrors 35 and 36 and guided to the upstream scraper mirror 34. Instead of the concave mirror 35, a convex mirror having a focal length smaller than 0 may be used.

In the first embodiment, the perforated guide mirror 121 shown in the second embodiment is used so that the second beam B2 overlaps the axis of the first beam B1 through the through hole 121b of the perforated guide mirror 121. It may be merged with the first beam B1. In this case, the second optical system 3 may have an optical component that maintains or reduces the diameter of the second beam B2, if necessary. Hereinafter, the second embodiment will be described focusing on the differences from the first embodiment.

(Second Embodiment)
FIG. 8 is a schematic view of the laser beam shaping device 101 according to the second embodiment. FIG. 9 is a diagram showing a cross-sectional shape of the laser beam L3 of FIG. As shown in FIG. 9, the laser beam L3 that is guided upstream of the first optical system 102 is an annular laser beam having an annular cross section.

The laser beam L3 of the present embodiment has a first beam B1 and a second beam B2 like the laser beam L1. The second beam B2 is an outer peripheral portion 90 of the annular laser beam and an inner peripheral portion 92 located inside the outer peripheral portion 90. The first beam B1 is an intermediate peripheral portion 91 located between the inner peripheral portion 92 and the outer peripheral portion 90 of the laser beam L3. The inner peripheral portion 92 is continuous with the intermediate peripheral portion 91, and the intermediate peripheral portion 91 is continuous with the outer peripheral portion 90. In the shaping device 101, in order to shape the laser beam L3 into a desired cross-sectional shape, the portions to be removed from the laser beam L3 are the outer peripheral portion 90 and the inner peripheral portion 92, and the remaining portions are the intermediate peripheral portion 91. The radial width (thickness) dimension W of the laser beam L3 can be appropriately set by adjusting the type of the optical system used in the shaping apparatus 101 and the like.

The first optical system 102 includes a perforated guide mirror 121, a guide mirror 22, a first mirror (scraper mirror) 123, a perforated guide mirror 124, and a second mirror 125 (hereinafter, also referred to as a guide mirror 125). The perforated guide mirror 121 and the guide mirror 22 guide the laser beam L3 to the first mirror 123. The perforated guide mirror 121 has a reflecting surface 121a and a through hole 121b. The first mirror 123 has a reflecting surface 123a and a through hole 123b. The reflecting surface 123a reflects the outer peripheral portion 90 of the laser beam L3. The through hole 123b passes through the intermediate peripheral portion 91 and the inner peripheral portion 92 of the laser beam L3.

The perforated guide mirror 124 reflects the intermediate peripheral portion 91 to guide the intermediate peripheral portion 91 to a predetermined optical path and passes the inner peripheral portion 92. The perforated guide mirror 124 has a reflecting surface 124a and a through hole 124b. The second mirror 125 reflects the inner peripheral portion 92 of the laser beam L2. As described above, the first optical system 102 individually has the first mirror 123 and the second mirror 125.

The second optical system 103 includes a second mirror 125, lenses 128, 135, and guide mirrors 136, 137, in addition to the convex lenses 31, 32, mirror 33, and mirror (scraper mirror) 34 of the first embodiment. The optical elements 125, 135, 136, 128, and 137 guide the inner peripheral portion 92 of the laser beam L3 as the second beam B2, and pass the second beam B2 through the through hole 121b of the perforated guide mirror 121 to the first beam B1. To join.

The lens 135 and the lens 128 are arranged here so as to reduce the diameter of the second beam B2. The lens 135 and the lens 128 may be arranged so as to maintain or expand the diameter of the second beam B2. When the second optical system 103 includes optical components such as a convex lens, a concave lens, and a parabolic mirror as an optical system for expanding or contracting the diameter of the second beam B2, the shape (outer diameter / inner diameter) of the second beam B2. It can be changed while maintaining the ratio etc.).

When the shaping device 101 is driven, the laser beam L3 is guided by the perforated guide mirror 121 from the upstream side to the downstream side in the light guide direction of the laser beam L3, and then passes through the through hole 34b of the upstream scraper mirror 34. Then, the guide mirror 22 guides the first mirror 123.

In the first mirror 123, the laser beam L3 passes through the through hole 123b and is reflected by the first beam B1 (intermediate peripheral portion 91) and the second beam B2 (inner peripheral portion 92) and the reflecting surface 123a. It is separated from the beam B2 (outer peripheral portion 90).

After that, the laser beam including the first beam B1 and the second beam B2 (inner peripheral portion 92) is guided by the perforated guide mirror 124. The first beam B1 is reflected by the reflecting surface 124a of the perforated guide mirror 124 and guided to a predetermined optical path, and the second beam B2 (inner peripheral portion 92) passes through the through hole 124b of the perforated guide mirror 124. .. The first beam B1 reflected by the reflection surface 124a is introduced into the emission optical system (here, the emission device 40) as the emission laser beam L4.

On the other hand, the second beam B2 (the outer peripheral portion 90 of the laser beam L3) reflected by the reflecting surface 123a is guided by the convex lenses 31 and 32, then reflected by the guide mirror 33 and guided by the upstream scraper mirror 34. Ru. After that, the second beam B2 is reflected by the reflecting surface 34a of the upstream scraper mirror 34 and merges with the first beam B1 while focusing.

Further, the second beam B2 (inner peripheral portion 92 of the laser beam L3) that has passed through the through hole 124b of the perforated guide mirror 124 is guided by the optical elements 125, 135, 136, 128, 137 and then perforated. It passes through the through hole 121b of the guide mirror 121 and joins the first beam B1.

In the present embodiment, at the confluence position of the laser beam L3 and the second beam B2 which is the inner peripheral portion 92 on the reflection surface 121a of the perforated guide mirror 121, the outer diameter of the second beam B2 which is the inner peripheral portion 92 Is sufficiently smaller than the inner diameter of the through hole 121b of the perforated guide mirror 121. Further, the outer diameter of the laser beam L3 at the confluence position is sufficiently larger than the inner diameter of the through hole 121b of the perforated guide mirror 121. The second beam B2, which is the inner peripheral portion 92, passes through the through hole 121b of the perforated guide mirror 121, is guided together with the laser beam L3, and overlaps with the first beam B1 so as to overlap the axis of the first beam B1. Will be merged.

FIG. 10 is a diagram showing the intensity distribution of the laser beam L3 of FIG. As shown on the upper side of FIG. 10, the intensity distribution of the laser beam L3, which is a circular laser beam, may have small peaks generated by the propagation or diffraction of the laser beam L3. In the present embodiment, both the outer peripheral portion 90 and the inner peripheral portion 92 of the laser beam L3 are cut (broken line portion in FIG. 10), and the cut portion is collected as the second beam B2 as shown in the lower side of FIG. Then, by merging with the first beam B1, the occurrence of power loss corresponding to the peak of the laser beam L3 is also prevented.

That is, according to the shaping device 101, even if the laser beam L3 is annular, the target can be irradiated with the emitted laser beam L4 having a desired shape while preventing thermal damage. In addition, power loss can be satisfactorily prevented by recovering the laser beam portion having a relatively high intensity generated by propagation and diffraction.

(Third Embodiment)
FIG. 11 is a schematic view of the laser beam shaping apparatus 201 according to the third embodiment. FIG. 12 is a diagram showing a cross-sectional shape of the laser beam L5 of FIG. FIG. 13 is a diagram showing a partial configuration of the second optical system 203 of FIG.

Similar to the second embodiment, the laser beam L5 guided upstream of the first optical system 202 is an annular laser beam having an annular cross section. The laser beam L5 has a first beam B1 and a second beam B2 like the laser beam L1. The first beam B1 is an outer peripheral portion 90 of the laser beam L5. The second beam B2 is an inner peripheral portion 93 located inside the outer peripheral portion 90 of the laser beam L5. The outer peripheral portion 90 and the inner peripheral portion 93 are continuous. In the shaping device 201, in order to shape the laser beam L5 into a desired cross-sectional shape, a portion removed from the laser beam L5 is designated as an inner peripheral portion 93, and a portion to be retained is designated as an outer peripheral portion 90.

The first optical system 202 includes a guide mirror 21, a guide mirror 22, and a perforated guide mirror 124. The second optical system 203 has at least one of an axicon lens and an axicon mirror. As an example, the second optical system 203 has guide mirrors 125, 136, convex axicon lenses 138, 139, and an upstream scraper mirror 34.

The convex axicon lenses 138 and 139 expand the inner diameter (and outer diameter) while maintaining the width (= (outer diameter-inner diameter) / 2) of the second beam B2 that has passed through the through hole 124b of the perforated guide mirror 124. To do. The convex axicon lenses 138 and 139 are arranged apart from each other with their tops facing each other. The apex angle θa of the convex axicon lens 138 is set to be larger than the apex angle θb of the convex axicon lens 139 so that the second beam B2 is focused. Instead of the convex axicon lens 138, a concave axicon lens having an apex angle θa larger than the apex angle θb may be used.

The second optical system 203 arranges the second beam B2 coaxially with respect to the laser beam L5 so as to surround the outside, and reduces the diameter toward the downstream side in the light guide direction. As a result, the second optical system 203 arranges the second beam B2 coaxially with respect to the first beam B1 so as to surround the outside, and reduces the diameter toward the downstream side in the light guide direction. , Join the first beam B1.

When driving the shaping device 201, the laser beam L5 is guided by the guide mirror 21 from the upstream side to the downstream side in the light guide direction of the laser beam L5, and then passes through 34b of the upstream scraper mirror 34 to pass through the guide mirror. It is guided by the perforated guide mirror 124 by 22.

In the perforated guide mirror 124, the laser beam L5 is separated into a second beam B2 (inner peripheral portion 93 of the laser beam L5) passing through the through hole 124b and a first beam B1 reflected by the reflecting surface 124a. .. The first beam B1 is introduced into the emission optical system (here, the emission device 40) as the emission laser beam L6.

On the other hand, the second beam B2 that has passed through the through hole 124b is guided by the optical elements 125, 136, 138, and 139, and then reflected by the reflecting surface 34a of the upstream scraper mirror 34. The second beam B2 is guided together with the laser beam L5 and merges with the first beam B1.

In the present embodiment, as in the first embodiment, at the confluence position of the first beam B1 and the second beam B2 on the reflection surface 34a, the inner diameter of the second beam B2 is a laser that has passed through the upstream scraper mirror 34. It is sufficiently larger than the outer diameter of the beam L5. As an example, the inner circumference of the second beam B2 at the confluence position is radially separated from the outer circumference of the laser beam L5 that has passed through the upstream scraper mirror 34. From this state, the second beam B2 merges with the first beam B1 while being focused toward the axial center of the first beam B1. The focusing of the second beam B2 is adjusted by, for example, setting the apex angles θa and θb of the convex axicon lenses 138 and 139.

According to the shaping device 201 having the above configuration, even if the laser beam L5 is annular, the target can be irradiated with the emitted laser beam L6 having a desired shape while preventing thermal damage. Further, the inner peripheral portion 93 of the laser beam L5 can be satisfactorily shaped while preventing power loss.

FIG. 14 is a diagram showing a partial configuration of a second optical system according to a modified example of the third embodiment. In this second optical system, a convex axicon mirror 141 is used instead of the convex axicon lens 138, and a concave axicon mirror 140 is used instead of the convex axicon lens 139. FIG. 14 shows the appearance of the convex axicon mirror 141.

The concave axicon mirror 140 is annular and has a reflecting surface 140a on the inner surface of the cone and a through hole 140b. The apex angle θc of the cone having the reflection surface 140a as the inner surface is smaller than the apex angle θd of the convex axicon mirror 141.

In this configuration, the second beam B2 that has passed through the through hole 140b of the concave axicon mirror 140 is reflected by the reflection surface 141a of the convex axicon mirror 141 and then reflected by the reflection surface 140a of the concave axicon mirror 140. Instead of the convex axicon mirror 141, a concave axicon mirror having an apex angle of the inner surface of the cone larger than the apex angle θc may be used.

By using such an Axicon optical system, the second beam B2 can be converted into an annular laser beam, and the outer diameter / inner diameter ratio is changed while maintaining the width dimension (see the width dimension W in FIG. 9). be able to.

As described above, since the second optical system according to the third embodiment and the modified example has at least one of the axicon lens and the axicon mirror, the second beam B2 is a circular laser beam even when the second beam B2 is an annular laser beam. The beam B2 can be merging well with the first beam B1.

In the present embodiment, the laser beam L5 that is guided upstream of the first optical system 202 may be a laser beam having a solid cross section. In this case, the solid second beam B2 that has passed through the through hole 124b of the perforated guide mirror 124 is converted into an annular beam having a radius of the second beam B2 and merged with the first beam B1. It is possible to obtain an emitted laser beam L6 whose cross section is shaped into a desired annular shape while preventing power loss.

(Fourth Embodiment)
FIG. 15 is a schematic view of the laser beam shaping device 301 according to the fourth embodiment. Similar to the second embodiment, the laser beam L7 guided upstream of the first optical system is an annular laser beam having an annular cross section. The second beam B2 is the outer peripheral portion 90 of the laser beam (see FIG. 12). The first beam B1 is a central portion (in other words, an inner peripheral portion 93) located inside the outer peripheral portion 90 of the laser beam L7.

The first optical system 302 includes a perforated guide mirror 121, a guide mirror 22, a downstream scraper mirror 23, and a guide mirror 24. The second optical system 303 includes a convex axicon lens 142, a convex axicon lens 143, a convex lens 144, 145, and a guide mirror 136, 137. The convex axicon lenses 142 and 143 are arranged so as to reduce the inner diameter while maintaining the width of the second beam B2. The convex lenses 144 and 145 are arranged so as to further reduce the diameter of the second beam B2 that has passed through the convex axicon lens 143.

When the shaping device 301 is driven, the laser beam L7 is guided by the perforated guide mirror 121 from the upstream side to the downstream side in the light guide direction of the laser beam L7, and then guided to the downstream scraper mirror 23 by the guide mirror 22. Will be done.

In the downstream scraper mirror 23, the laser beam L7 has a first beam B1 that passes through the through hole 23b of the downstream scraper mirror 23 and a second beam B2 that is reflected by the reflection surface 23a (the outer peripheral portion 90 of the laser beam L7). Is separated into. The first beam B1 is guided by the guide mirror 24 and introduced into the emission optical system (here, the emission device 40) as the emission laser beam L8.

On the other hand, the second beam B2 reflected by the reflecting surface 23a is guided by the optical elements 142, 143, 144, 145, 136, 137, and after being focused by the optical elements 142, 143, the perforated guide mirror. It passes through the through hole 121b of 121, is guided together with the laser beam 7, and merges with the first beam B1.

As described above, according to the shaping device 301, even if the laser beam L7 is annular, it is possible to irradiate the target with a laser beam having a desired shape while preventing power loss and thermal damage.

The present invention is not limited to each of the above embodiments, and its configuration can be changed, added, or deleted without departing from the spirit of the present invention. Each of the above embodiments may be combined with each other.

The method of deflecting a part of the laser beam by the first optical system may be a method other than the method of reflecting the laser beam. Further, in each of the above embodiments, the configuration in which the first optical system merges the second beam with the first beam on the upstream side of the separation position where the laser beam is separated into the first beam and the second beam in the shaping apparatus is exemplified. However, the present invention is not limited to this, and the second beam may be merged with the first beam on the downstream side of the separation position.

As described above, the present invention has an excellent effect of reducing the power loss of the laser beam and improving the focusing performance and intensity of the laser beam at the irradiation position of the target to which the laser beam is irradiated. Therefore, it is beneficial to widely apply the present invention to a laser system capable of exerting the significance of this effect.

B1 1st beam B2 2nd beam L1, L3, L5, L7 Laser beam 1,101,201,301 Laser beam shaping device 2,202,302 1st optical system 3,203,303 2nd optical system 23 Downstream scraper Mirror 23a Reflective surface of downstream scraper mirror 31,32 Lens (convex lens)
34 Upstream scraper mirror 34a Reflective surface of upstream scraper mirror 80,90 Outer circumference 91 Intermediate circumference 92,93 Inner circumference 123 First mirror 125 Second mirror 138, 139, 142, 143 Convex axicon lens (axicon) lens)
140, 141 Concave Axicon Mirror (Axicon Mirror)

Claims (11)

A first optical system that separates the laser beam into a first beam shaped into a desired cross-sectional shape and a second beam other than the first beam by deflecting a part of the laser beam.
A second optical system that joins the second beam coaxially with the first beam,
A laser beam shaping device. The second beam is an outer peripheral portion of the laser beam.
The laser beam shaping apparatus according to claim 1, wherein the first beam is a central portion located inside the outer peripheral portion of the laser beam. The second optical system is arranged by arranging the second beam coaxially with respect to the first beam and surrounding the outside, and reducing the diameter toward the downstream side in the light guide direction. The laser beam shaping apparatus according to claim 2, which merges with the first beam. The first optical system is a downstream scraper mirror having an annular reflecting surface that allows the central portion of the laser beam to pass as the first beam and reflects the outer peripheral portion of the laser beam as the second beam. Have,
The laser beam shaping apparatus according to claim 2 or 3, wherein the reflecting surface of the downstream scraper mirror is arranged so as to be inclined with respect to the optical axis of the first beam. The second optical system is an annular reflection that allows the laser beam to pass upstream of the downstream scraper mirror and merges the second beam reflected by the downstream scraper mirror with the first beam. The laser beam shaping apparatus according to claim 4, which has an upstream scraper mirror having a surface. The laser beam that is guided upstream of the first optical system is an annular laser beam having an annular cross section.
The second beam is an outer peripheral portion of the annular laser beam and an inner peripheral portion located inside the outer peripheral portion.
The first beam is an intermediate peripheral portion located between the inner peripheral portion and the outer peripheral portion of the annular laser beam.
The first optical system has a first mirror that reflects the outer peripheral portion of the annular laser beam and a second mirror that reflects the inner peripheral portion of the annular laser beam, according to claim 1. The laser beam shaping device described. The laser beam that is guided upstream of the first optical system is an annular laser beam having an annular cross section.
The first beam is an outer peripheral portion of the annular laser beam.
The second beam is an inner peripheral portion located inside the outer peripheral portion of the annular laser beam.
The second optical system is arranged by arranging the second beam coaxially with respect to the first beam and surrounding the outside, and reducing the diameter toward the downstream side in the light guide direction. The laser beam shaping apparatus according to claim 1, which merges with the first beam. The laser beam shaping apparatus according to claim 3, wherein the laser beam guided upstream of the first optical system is an annular laser beam having an annular cross section. The laser beam shaping apparatus according to any one of claims 6 to 8, wherein the second optical system has at least one of an axicon lens and an axicon mirror. The laser beam shaping apparatus according to any one of claims 1 to 9, wherein the second optical system has at least one of a convex lens, a concave lens, a spherical mirror, and a parabolic mirror. The second optical system performs the second beam a plurality of times between a separation position for separating the first beam and the second beam and a merging position for merging the second beam with the first beam. The laser beam shaping apparatus according to any one of claims 1 to 10, which is circulated.

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