JPH07101762B2 - Laser processing equipment - Google Patents

Description

TECHNICAL FIELD The present invention relates to a laser processing apparatus having improved beam quality.

[Prior Art] FIG. 24 is a schematic view of a conventional laser processing apparatus for performing surface modification of metal, high-speed drying of padding or wet paper. In the figure, (1) is a total reflection mirror, (4) is an exit mirror, (3) is a laser medium, and (7) is a laser resonator (6) composed of a total reflection mirror (1) and an exit mirror (4). A laser beam generated inside, (8) a laser beam extracted from the laser resonator (6) to the outside, (9) a bent mirror, (8a) a laser beam reflected by the bent mirror (9), ( 10) is the work piece. (5)
Is a non-reflective coating applied to the outer surface of the exit mirror (4), and (5a) is a partially reflective coating applied to the inner surface of the exit mirror (4) to make the exit mirror (4) partially reflective.

Next, the operation will be described. A laser beam (7) traveling back and forth between the total reflection mirror (1) and the exit mirror (4) is amplified by the laser medium (3), and a part of the laser beam is taken outside the exit mirror (4) as a laser beam (8). Will be issued. The extracted laser beam (8) is guided to the work piece (10) by the vent mirror (9), and the work piece (1
If 0) is a metal, surface modification, buildup, etc., is performed,
If the workpiece (10) is wet paper, it is dried at high speed.

In such a laser processing apparatus, in order to perform high-speed processing, it is usual to enlarge the laser medium (3) to increase the output. In that case, the laser beam can be efficiently emitted from the large laser medium (3). The cross-sectional area of the laser beam (7) must be increased in order to extract the intensity distribution.
(Showa 49, Maruzen) It becomes the so-called higher mode described in detail.

Further, FIG. 26 is a schematic diagram of an example of a laser processing apparatus for cutting and welding a work piece, which is shown in “Practical Laser Processing” by Masanobu Hamasaki (published by Tech Publishing Co., February 20, 1986). is there. Incidentally, the same or corresponding parts as those of the conventional example shown in FIG. 24 are designated by the same reference numerals, and the description thereof will be omitted.

In the figure, (21) is an aperture, (9) is a vent mirror, (11) is a condenser lens, (22) is a processing gas inlet,
(23) is an arrow indicating the flow of the processing gas.

Next, the operation will be described. The laser beam (8) extracted from the laser resonator (6) is guided to the lens (11) as a laser beam (8a) by the bent mirror (9) and is condensed to obtain a high power density and Inlet (22)
Workpiece (10) with more guided laser gas (23)
Laser processing such as cutting and welding.

By the way, a high-quality and high-power laser beam is required to perform high-performance laser processing, so this device obtains a high-quality laser beam by limiting the beam outer diameter with the aperture (21). . When the aperture (21) is sufficiently small, a Gaussian mode having a normal distribution intensity distribution as shown in FIG. 27 (a) is generated, and this laser beam (8) is generated by the lens (11), etc. Since it can be narrowed down as shown in b), a laser beam having a high power density can be obtained. On the other hand, when the inner diameter of the aperture (21) is increased, a multimode laser output having a poor light converging property can be obtained as shown in FIG.

FIG. 28 is a diagram showing cutting performance when laser cutting of iron is actually performed using these beam modes. In the figure, B shows the case of Gauss mode, laser output 500W, A in the figure shows multimode, laser output 1000W. Although the multimode A has a higher laser output, the cutting performance is inferior, and it can be seen how the quality of the laser beam mode is important for laser processing.

Further, FIG. 29 is a schematic view of a conventional laser processing apparatus for performing modification, welding, etc. of a work piece shown in the above "practical laser processing". Incidentally, the same or corresponding parts as those of the conventional example shown in FIGS. 24 and 26 are designated by the same reference numerals, and the description thereof will be omitted.
In the figure, (11) is a processing lens that forms a condenser element for the laser beam (8).

Next, the operation will be described. The laser beam (7) that reciprocates between the exit mirror (4) of the laser resonator (6) and the total reflection mirror (1) is amplified by the laser medium (3) and the intensity of the laser beam (7) exceeds a certain level. Then, a part of the laser beam (7) is extracted as a laser beam (8) to the outside. The laser beam (8) thus extracted to the outside is focused by the processing lens (11), is irradiated with high power density on the workpiece (10),
Perform laser processing such as modification and welding of the workpiece (10).

In this case, a high-power laser beam (8) is required for efficient laser processing of the workpiece (10). However, in order to stably take out the high-power laser beam (8) from the exit mirror (4), the beam intensity density at the exit mirror (4) must be lowered, and therefore the laser beam (7) has a large cross-sectional area. It is necessary to make it. However, when a laser beam (8) having a large cross-sectional area is taken out from the exit mirror (4), a laser beam (8) called multimode having an extremely high intensity at both ends as shown in FIG. 30 (a) is obtained. The laser beam (8) is further focused by the processing lens (11) and the like into a laser beam (8b) having high intensity at both ends as shown in FIG.

31 and 32 are explanatory views showing an example of a conventional composite laser processing apparatus disclosed in Japanese Patent Laid-Open No. 60-4282, and FIG. 31 shows a state in which the laser processing apparatus is configured for welding. Show, first
Figure 32 shows the state of being configured for quenching.

In FIG. 31, (12) is an enlarged total reflection mirror of the laser resonator (6), (1) is a total reflection collimating mirror, and (3).
Is a laser medium, (13) is a mirror with a hole, and (14) is a window. Further, (15a) is a ring-shaped laser beam extracted from the window (14) to the outside of the laser resonator (6), (11) is a lens which is a condensing element of the laser beam (15a), and (10) is a target. It is a processed product. Further, in FIG. 32, (9) is a bent mirror, and (14a) is a partial reflection mirror.

Next, the operation will be described. First, in the configuration shown in FIG. 31, the magnifying total reflection mirror (12) and the total reflection collimator mirror (1) constitute a so-called unstable resonator, and the laser beam that reciprocates between the two mirrors (12) and (1). (15) is amplified by the laser medium (3). This laser beam (15) is taken out as a ring-shaped laser beam (15a) to the outside of the laser resonator (6) through the window (14) by the mirror (13) with a hole on the outer circumference every reciprocation. , The laser beam is focused on the workpiece (10) by being focused by the lens (11). The laser beam (15a) thus taken out is mainly used for welding of iron or the like.

Next, in the configuration of FIG. 32, a total reflection collimating mirror (1), a vent mirror (9), and a partial reflection mirror (14a)
Constitutes a so-called stable resonator, and the laser beam (15) that reciprocates between the total reflection collimating mirror (1) and the partial reflection mirror (14a) has a partial reflection mirror. (14a) is taken out of the laser resonator (6) and focused by the lens (11) to perform laser processing such as surface treatment of the workpiece (10).

FIG. 33 (a) shows the cross-sectional shape (beam pattern) of the intensity distribution of the laser beam (15a) generated by the configuration shown in FIG. 31, and FIG. 33 (b) shows an example of the focused beam pattern. That is, the ring-shaped laser beam (15a) shown in FIG. 33 (a) is focused as a medium-high beam with side peaks due to the diffraction effect as shown in FIG. 33 (b). Since this concentrated beam pattern has a high central peak, it efficiently welds an iron plate or the like, or sharply melts into an iron plate or the like, but it cannot be used for laser surface treatment which requires a smooth beam pattern. Further, such a ring-shaped laser beam is hardly used for laser cutting, which requires a long depth of focus, because the beam shape largely changes before and after focusing.

34 (a), (b), and (c) are examples of changes in the beam shape shown in FIG. 33 (b). That is, when the ratio of the inner diameter to the outer diameter is 2, and the ring-shaped laser beam with an outer diameter of 20 mm is focused by a lens with a focal length of 400 mm, the focus is 20 mm before (the third
An example of the focused beam pattern at the position of FIG. 4 (a), the position of the focus (FIG. 4 (b)), and the position 20 mm deeper than the focus ((c) of the same figure) is shown. As can be seen from the figure, the central peak is low before and after the focal point, and the side peaks are spread far away.

Generally, in the welding process requiring a high power density, it is considered that only the power contained in the central mountain is used for the laser process. In this case, when calculating what percentage of the total laser power is included in the central mountain, it is about 30%, 50% and 30% in the same figures (a), (b) and (c), respectively. Therefore, it is considered that the laser processing efficiency is deteriorated before and after the focus, and it can be said that the distance at which a substantially constant laser processing efficiency is obtained before and after the focus, that is, the depth of focus is shallow. Therefore, it can hardly be used for laser cutting which requires a longer depth of focus than welding.

On the other hand, when the surface treatment of the comparative processed product (10) is performed, it is configured as a so-called stable resonator as shown in FIG. That is, the mirror with a hole (13) used in the configuration of FIG. 31.
Is changed to a bent mirror (9), and the window (14) is changed to a partial reflection mirror (14a). The laser beam generated from the laser resonator (6) in such a configuration is
As shown in FIG. 35 (a), it becomes a mountain shape with peaks at both ends, and it is condensed by the lens (11) etc. in almost the same shape as shown in FIG. 35 (b) and used for laser surface treatment of iron or the like. . However, this focused beam pattern has a problem that uneven surface treatment is performed because the end portion is strong.

[Problems to be Solved by the Invention] In the conventional laser processing apparatus as described above, the apparatus shown in FIG. 24 performs laser processing using a higher order mode. As shown in (1), since the both ends have a non-uniform intensity distribution with extremely high intensity, there is a problem that uniform laser processing cannot be performed.

Further, in order to obtain a high quality laser beam with the device shown in FIG. 26, it is necessary to use a small aperture (21), and it is not possible to extract power from the laser medium (3) sufficiently efficiently. Increasing the laser output (8) increases the beam intensity density on the lens (11), not only deforming the lens (11), but in some cases, causing destruction.

Further, the apparatus shown in FIG. 29 must use a laser beam (8) having a remarkably high non-uniform intensity distribution at both ends when processing a workpiece with a high power laser beam (8). For this reason, the laser processing is non-uniform, and the exit mirror (4) is also non-uniformly heated, so that the laser output becomes unstable when the output is increased, and in a remarkable case, the exit mirror (4) is destroyed. There was a problem such as coming to.

Further, in the combined laser processing apparatus shown in FIG. 31 and FIG. 32, the laser resonator (6) must be recombined depending on the type of laser processing of the workpiece (10), which is extremely troublesome and takes time to set up. Not only that, but there was also the problem that the processing range was narrow.

The present invention provides a laser processing apparatus capable of performing a uniform laser processing by obtaining a laser beam having a stable and uniform intensity distribution from a laser medium having a large cross-sectional area, and a high-quality laser beam from a laser medium with high efficiency. An object of the present invention is to obtain a laser processing apparatus that can be taken out and that does not destroy the lens even when the output is increased.

Furthermore, the present invention can be performed without changing the laser cavity.
It is an object of the present invention to obtain a composite type laser processing apparatus capable of performing various kinds of processing such as laser cutting, welding and surface treatment of a work piece.

[Means for Solving Problems] A laser processing apparatus according to a first aspect of the present invention is directed to a laser medium, a collimating mirror opposed to each other with the laser medium sandwiched therebetween, a partially transmissive portion in the central portion, and a non-reflective portion in the peripheral portion. And a magnifying mirror that magnifies and reflects the laser beam toward the collimator mirror at the partially transmissive portion, a laser beam that passes through the partially transmissive portion of the magnifying mirror, and a laser beam that passes through the non-reflective portion. An unstable resonator having a phase difference adjusting means for adjusting and outputting a phase difference between the phase difference and a bent mirror for guiding an output beam having a phase difference adjusted by the phase difference adjusting means to a workpiece. It is characterized by.

A laser processing apparatus according to a second aspect of the present invention includes the unstable resonator and a condensing unit that condenses an output beam whose phase difference is adjusted by the phase difference adjusting unit onto a workpiece. It is what

[Operation] In the first aspect of the invention, the output beam of the unstable resonator has a hollow shape having a large beam cross-sectional area and a uniform intensity distribution, and is further transmitted through the partially transmitting portion of the magnifying mirror by the phase difference adjusting means. Since the phase difference between the laser beam to be irradiated and the laser beam transmitted through the non-reflecting portion is adjusted, the beam shape is adjusted to be suitable for the purpose of processing. Then, the output beam adjusted in this way is guided to a workpiece by a bent mirror, and laser processing is performed.

In the second invention, the output beam whose phase difference is adjusted by the phase difference adjusting means is further focused on the workpiece by the focusing means, and laser processing such as cutting and welding of the workpiece is performed.

[Examples] The present invention uses, as a laser resonator, the invention filed by the applicant as Japanese Patent Application No. 61-291786. Therefore, this laser resonator will be described first.

FIG. 1 is a sectional side view showing an example of the laser resonator. In the figure, (4) is a convex mirror that also serves as a wind mirror, and a partial reflection film (20) having a partial reflectance is provided in the center of the surface facing the collimating mirror (1).
Work as a magnifying mirror. A non-reflective coating film (5) is provided on the peripheral portion and the other surface side of the partial reflection film (20).

Next, the operation will be described. The collimating mirror (1) and the partial reflection film (20) of the convex mirror (4) constitute a so-called unstable resonator, and the reflection film (20) of the convex mirror (4)
The laser beam (7) reflected and expanded by the laser beam is amplified by the laser medium (3) and collimated mirror (1).
Is collimated into a parallel beam by the laser beam and is taken out as a laser beam (8) from the convex mirror (4) to the outside. This laser beam (8) passes through the partially reflective film (20),
The part that passes through the non-reflective coating film (5), and the part that passes through the partial reflection film (20) is partially transmissive, and the laser beam (8) is a clog. The M value defined by is equivalent to infinity.

2 (a) and 2 (b) show a case where a laser beam generated by an unstable resonator according to an example of the related art (FIG. (A)) and this laser resonator (FIG. 2 (b)) is focused by a lens. It is a characteristic view which shows a pattern shape typically, a horizontal axis is a distance from an optical axis, and a vertical axis is beam intensity.

In this experiment, the reflectance of the partial reflection film (20) is 50% and the partial reflection film (20)
The ratio of the beam diameter to the beam outer diameter was set to 1.5 (that is, a stable resonator was prepared by providing a magnifying mirror of a conventional unstable resonator with M = 1.5 with a 50% partial transmission portion).

Further, the curvatures of both surfaces of the convex mirror (4) were the same (the thickness was constant) so that the laser beam (8) was a parallel beam even after passing through the convex mirror (4). Figure 2 (a),
Comparing the respective focusing performances shown in (b), the laser resonator used in the present invention ((b) in the figure) has a high central intensity and can obtain a laser beam concentrated on the optical axis. I understand. The central strength mountain (main lobe)
Contains about 82% of the total laser power, which is almost equivalent to the theoretical value of 80% at infinity for the M value of the conventional unstable resonator, It can be seen that the light-collecting property close to the theoretical limit is obtained.

Furthermore, in the above example, the difference between the phase change when passing through the non-reflective coating film (5) and the phase change when passing through the partial reflection film (20) is small. A uniform laser beam (8) was obtained, but when the reflectance of the partial reflection film (20) was increased to increase the film thickness of the partial reflection film (20), the laser beam (8) was collected due to the phase difference between the two. Light performance deteriorates. For example, Fig. 3 shows the diameter (focus spot diameter) of the point at which 1 / e ² times the axial intensity at the focus point is reached, and the ratio of the laser power contained in the inside diameter to the total (power concentration). It is a characteristic diagram showing the relationship with the phase difference, the horizontal axis is the phase difference (degree), the vertical axis is the focused spot diameter (μm)
And power concentration (%). The curve (A) shows the relationship between the focused spot diameter and the phase difference, and the curve (B) shows the relationship between the power concentration and the phase difference. The M value is 1.5,
The partial transmittance of the magnifying mirror was 50%. Further, FIG. 3 is based on the result of calculating the intensity distribution at the condensing point using the laser beam generated in the resonator by wave calculation. In general, it can be determined that the smaller the spot diameter and the larger the power concentration degree, the better the light focusing performance. However, in FIG. 3, for example, if the phase difference is canceled within 0 ° to 45 °, favorable results can be obtained for both the power concentration and the spot diameter. In particular, it can be seen that the spot diameter remarkably deteriorates and the condensing performance deteriorates.

In this case, as shown in FIG. 4 (a) or (b), a portion having the same diameter as the partial reflection film (20) at the center of the collimating mirror (1) surface (FIG. 4 (b)), or the above A reflective thin film (10) made of a metal thin film may be provided in the peripheral portion (see FIG. 10A) except for the central portion, and the thickness may be configured to cancel the phase difference. For example, if the phase is advanced by θ ° when passing through the partial reflection film (20) than when passing through the coating film (5), the thickness d of the metal thin film (10) is (Where λ is the wavelength of the laser beam).

Further, the same thing as this, as shown in FIGS. 5 (a) and 5 (b), a concave portion (FIG. 5 (a)) having the same diameter as that of the partial reflection film (20) is formed in the central portion of the collimator mirror (1) or Convex (Figure (b))
It can also be realized by providing a stepped portion (11). Further, as shown in FIGS. 6 (a) and 6 (b), a convex or concave step portion (40) is provided on the convex mirror (4) side, and a magnifying mirror portion, that is, a portion coated with a partial reflection film (20) is enlarged. It can also be realized by providing a step between the periphery of the mirror, that is, the portion coated with the antireflection coating film (5). In this case, the size of the step may be determined based on the equation [1].

Further, in the above example, the case where the convex mirror is used as the expanding mirror of the unstable resonator is shown. However, as shown in FIG. 7, the concave mirror (41) is used to once expand the beam after condensing the beam in the resonator. Also in the case of an object, a concave film can be similarly generated even when a reflecting film (20) having a partial reflectance is provided at the center of the concave mirror (41) and the magnifying mirror has a partial transmittance.

It should be noted that FIGS. 4 to 7 all show the cross-sectional structure of the laser device of the present invention with the box body covering the surroundings omitted.

Further, in all of the above examples, the magnifying mirror and the wind mirror are integrated, but as in the conventional case, the magnifying mirror having a concave or convex mirror having a partial transmittance is provided on the wind mirror surface. May be.

FIG. 8 is a schematic view of an embodiment of the laser processing apparatus according to the first invention. In the figure, L is a laser resonator having the same structure as the laser resonator shown in FIGS. In addition, (9) is a bent mirror, and (10) is a workpiece.

Next, the operation will be described. The laser beam (7) expanded by the partial reflection coating film (20) at the center of the convex mirror (4) is amplified by the laser medium (3) while reciprocating between the collimating mirror (1) and the laser beam (7). Although it returns as 7a), a part of the central part and the whole part around it are combined and taken out as a laser beam (8).

In this way, by expanding the laser beam, the generation of higher-order modes is suppressed while obtaining a larger beam cross-sectional area,
The middle-highest lowest-order mode as shown in FIG. 9 (a) is generated inside, but the central part is partially reflected by the convex mirror (4), so that as shown in FIG. 9 (b) outside. A laser beam (8) with a substantially uniform beam intensity is obtained.

When the laser beam (8) having a substantially uniform beam intensity is guided onto the workpiece (10), it changes its shape to some extent by diffraction (FIG. 7 (c)), but the uniformity is maintained and the properties and uniformity are kept. It can be laser processed.

In the above-mentioned embodiment, the phase difference between the central portion of the convex mirror (4) and the laser beams passing therethrough is set to 0, but this may be changed, for example, by changing the thickness of the partial reflection coating film (20). The shape of the laser beam of the workpiece may be adjusted by providing a step at the center of the collimator mirror (1) and adjusting the phase difference. FIG. 9 (d) is the same device as that for confirming the beam modes shown in FIGS. 9 (a) to 9 (c), for example, in which the laser beam passing through the central portion of the convex mirror (4) is It shows a beam pattern on a work piece when it is configured so that the phase advances by 90 °. The laser beam has a narrow width and has a substantially rectangular beam shape.

Next, FIG. 10 is a schematic view of a laser processing apparatus according to the second invention, and L is a laser resonator. (9) is a bent mirror, (8a) is a laser beam folded by the bent mirror (9), (11) is a processed lens, (10) is a workpiece,
Reference numeral (25) is a gas nozzle having a processing lens (11) mounted therein, (22) is a processing gas inlet, and (23) is an arrow indicating the flow of the processing gas.

Next, the operation will be described. Laser beam (7) partially expanded and reflected by the partial reflection film (20) on the convex mirror (4)
Is reflected by the collimating mirror (1) as a parallel beam (7a), the central part of which is partially transmitted by the exit mirror (4), the peripheral part is taken out as it is, and both are combined to form a laser beam (8). Become. Laser beam (8)
The quality of can be regarded as equivalent to the case where the aperture (21) is made sufficiently small in the conventional laser resonator shown in FIG. 25, and only the beam diameter is increased due to the expansion.

Further, since the central portion of the laser beam (7a) partially passes through the convex mirror (4), the laser beam (8) extracted to the outside
Has a crushed shape compared to a Gaussian beam. FIG. 11 (a) shows an example of the shape of a laser beam generated using a discharge-excited CO ₂ laser with the same resonator length (distance between resonator mirrors) as in the conventional example. The resonator has a magnifying power of 2, the partial reflection film (20) has an outer diameter of 20 mm, and a transmittance of 50%.
Is. Although this beam shape was taken on the upper surface of the lens, it was found that a beam having a skirt-spreading shape that was about 2.5 times larger than that of the conventional example shown in FIG. 27 was obtained. It has also been confirmed that this laser beam is a high quality beam which is condensed by the lens (11) to an extremely high level as shown in FIG.

FIG. 12 is a diagram showing oscillation characteristics using the same laser medium. In the figure, the curve indicated by B indicates the conventional example, and the curve indicated by A indicates the oscillation characteristic according to the present invention. It can be seen from the figure that the present invention significantly improves the oscillation efficiency.

Although the above embodiment did not touch on the polarization of the laser beam, circular polarization of the laser beam is indispensable for high-precision cutting of metal, and a folding mirror provided in the resonator as shown in FIG. Linear polarization element (1
The laser beam may be linearly polarized by 7) and then circularly polarized externally by a circular polarization element (18) such as a retarder mirror for laser processing.

Moreover, although the phase difference between the two beams passing through the central part transmission part (20) of the convex mirror (4) and its peripheral part was not touched, if the phase difference is adjusted, the shape of the focused laser beam will be improved. Can be changed. FIG. 14 shows the relationship between the phase difference for the laser beam partially transmitted through the center of the beam passing through the peripheral portion and the on-axis intensity of the focused beam, and FIG. 15 (a) shows that the phase is completely canceled. A schematic diagram of the shape of the focused beam in the case of the above is shown in FIG. When a phase difference occurs, the on-axis strength decreases and the beam becomes divergent, but such a beam shape is desirable in the field of crevice welding and the like, and in the field of cutting, the axial strength is high and the phase difference of the width is narrow. A beam shape with less radiation is desirable. The phase difference may be adjusted by adjusting the optical path lengths of the two beams, for example, by adjusting the thickness of the partially reflective coating film. Next, FIG. 16 is a schematic view of a laser processing apparatus according to another embodiment of the second invention. Since the laser resonator is the same as the laser processing apparatus of the first invention shown in FIG. 8, its description is omitted. In the figure, (16) is a condenser lens, (11) is a processed lens, and (10) is a workpiece.

The operation of the present embodiment configured as described above will be described below. The laser beam (7) partially reflected by the partial reflection coating film (20) provided in the central portion of the inner surface of the convex mirror (4) is expanded and reflected and collimated by the total reflection mirror (1) to move inside the laser resonator. It is amplified by the laser medium (3) during the round trip. Laser beam (7a) which is reflected by the total reflection mirror (1) and becomes parallel
Among them, the central part is partially transmitted by the partially reflective coating film (20), and the outer peripheral part is entirely transmitted by the non-reflective coating film (5). Further, the partially transmitted laser beam and the totally transmitted laser beam are combined as a hollow laser beam (8) and extracted to the outside of the laser resonator (6). This laser beam (8) is condensed by the condenser lens (16) on the vicinity of the processing lens (11) (laser beam (8a)) and further condensed by the processing lens (11) (laser beam (8b)). )) The workpiece (10) is processed.

As described above, in the present embodiment, the central part of the laser beam is partially transmitted and the outer peripheral part is completely transmitted. Therefore, the laser beam taken out to the outside as a combination of the two is a laser beam having a substantially uniform intensity distribution with crests. And output to the outside of the laser resonator.

FIG. 17 (a) shows the curvature of the convex mirror (4) −5 m, the curvature of the total reflection mirror (1) 7.5 m, and the distance between the convex mirror (4) and the total reflection mirror (1) 1.25 m in the CO ₂ laser processing apparatus. FIG. 6 is an intensity distribution diagram showing an example of the intensity distribution of the laser beam (8) when the transmittance of the central portion of the convex mirror (4) is 50% and the beam outer diameter is 20 mm. Since this laser beam (8) is in the middle, when it is condensed by the condenser lens (16) having a focal length of 10 m, for example, a Gaussian intensity distribution as shown in FIG. When the focused laser beam (8a) is further focused by the processing lens (11), it has a uniform intensity distribution immediately after the exit mirror (4) as shown in FIG. A laser beam (8b) having the same type and reduced power density is obtained.

When the focal lengths of the condenser lens (16) and the processing lens (11) are f ₁ and f ₂ , respectively, when the processing lens (11) is at the focus of the condenser lens (16), At the point separated from the processing lens (11) by the distance Z, the beam intensity distribution on the incident side of the condenser lens (16), that is, immediately after the output from the convex mirror (4) has the same shape as that of the workpiece (1
0) obtained above. However, since generally f ₂ << f ₁ , Z is almost f ₂ , and a uniform intensity distribution immediately after the exit from the convex mirror (4) is obtained at almost the focus of the processing lens (11).

In the above description, the case where the laser beam is focused on the processing lens by the transmissive lens has been described, but a spherical reflection mirror may be used for this focusing. Further, in the above description, the case where the condenser lens (16) is provided outside the laser resonator to condense the laser beam (8a) on the processing lens (11) has been described. For example, as shown in FIG. The curvature of the inner surface and the outer surface of the convex mirror (4a) may be provided so that the convex mirror (4a) itself acts as a condenser lens. Further, as shown in FIG. 19, the radius of curvature of the total reflection mirror (1) may be reduced to generate a focused laser beam (8).

20 (a), (b) and (c) are schematic views of a laser processing apparatus according to still another embodiment of the second invention. In the figure, L is a laser resonator, (7) is a laser beam which is partially reflected by the partial reflection film (20), and (7a) is a laser beam (7) which is reflected by the total reflection collimating mirror (1) and is a parallel beam. The laser beam (8b) is a laser beam of the laser beam (7a) that has passed through the partial reflection film (20) on the inner surface of the convex mirror (4), and (8c) is a convex mirror (4) of the laser beam (7a). ) A laser beam that has passed through the antireflection film (5) on the inner surface, and (8) is a laser beam (8b), (8)
c) is the combined laser beam. Also, (1
1) is a condenser lens, (10) is a workpiece, (22) is a gas inlet, (23) is a cutting assist gas such as oxygen introduced into the nozzle from the gas inlet (22), ( 24) is a welding gas such as argon.

The operation of the present embodiment configured as described above will be described below. The convex mirror (4) and the total reflection collimating mirror (1) form one kind of unstable resonator. The laser beam (7) expanded and partially reflected by the partial reflection film (20) on the inner surface of the convex mirror (4) is reflected by the total reflection collimating mirror (1) and reciprocates in the laser resonator.
At this time, the laser beam (7) is amplified by the laser medium (3) to become a parallel laser beam (7a), and the convex mirror (4)
Come back to. Of this laser beam (7a), the central part passes through the partial reflection film (20) as a laser beam (8b), and the outer peripheral part passes through the non-reflection film (5) as a laser beam (8c). Taken out of. At this time, both the laser beams (8b) and (8c) are combined into the laser beam (8).

The laser beam (8) thus taken out is not only in phase but also in the middle, so that when it is focused by the condenser lens (11), it has a Gaussian beam pattern without side peaks. To be processed (1
0) is laser processed.

21 (a), (b), and (c) show a laser beam (8) with an outer diameter of 20 mm and a condensing lens (1) with a focal length of 400 mm, respectively.
The following shows the beam patterns of 3 points at the position 20 mm before the focus, the position of the focus, and the position 20 mm deeper than the focus when the light is focused in 1). As is clear from the figure, a smooth Gaussian-shaped laser beam pattern without side peaks is obtained with almost the same shape before and after the focus of the condenser lens (11). Therefore, if the workpiece (10) such as iron is irradiated with this laser beam (8) together with the processing gas (23) which is oxygen gas as shown in FIG. ) Can be cut.
If the laser beam (8) is applied to the workpiece (10) together with a processing gas (24) such as argon gas as shown in FIG. 2B, the workpiece (10) is welded. You can Further, when the gas is not blown, the surface treatment of the work (10) can be performed by irradiating the work (10) with the laser beam (8) as shown in FIG. I can.

In the above description, various laser processings were all performed at the focal point of the lens. However, when performing surface treatments that do not require high power density, as shown in FIGS. 22 (a) and 22 (b), The workpiece (10) may be moved before and after the focal point of the optical lens (11), or as shown in FIGS. 23 (a) and 23 (b), the focal length of the condenser lens (11). Alternatively, the power density on the workpiece (10) may be adjusted and applied to various laser processing.

[Advantages of the Invention] As described above, according to the first aspect of the present invention, a beam output having a large output, a large beam cross-sectional area, and a uniform intensity distribution with a concentric shape can be obtained, and the phase difference adjusting means is provided. Since the beam shape is adjusted to be suitable for the purpose of processing, various laser processing can be performed at high speed and with high quality.

Further, according to the second aspect of the invention, since the beam shape is condensed in a high and medium shape by the light converging means, it is possible to efficiently perform cutting, welding, surface treatment and the like of the workpiece. Also,
There is an effect that it is possible to deal with various types of laser processing with one device without requiring replacement of the laser resonator.

[Brief description of drawings]

FIG. 1 is a cross-sectional side view showing an example of a laser resonator forming an essential part of the present invention, and FIGS. 2 (a) and 2 (b) are characteristic diagrams showing focusing characteristics of a conventional laser resonator and an example of this laser resonator, respectively. , FIG. 3 is a characteristic diagram showing the relationship between the focal spot diameter at the focal point, the power concentration degree, and the phase difference, FIG. 4 (a), (b), FIG. 5 (a), (b). , FIG. 6 (a), (b), and FIG. 7 are cross-sectional side views showing other examples of the laser resonator, FIG. 8 is a schematic view of an embodiment of the first invention, and FIG. a) ~
(D) is a characteristic diagram showing the light condensing characteristic, FIG. 10 is a schematic diagram of an embodiment of the second invention, FIGS. 11 (a) and (b) are the light condensing characteristic diagrams, and FIG. 12 is a book. A diagram showing the relationship between the laser output and the discharge power between the invention and the conventional device, FIG. 13 is a schematic diagram of the embodiment of the second invention, and FIG. 14 shows the relationship between the phase difference and the axial strength. Fig. 15 (a) and (b) are the same light collection characteristic diagram,
FIG. 16 is a schematic diagram of another embodiment of the second invention, and FIGS. 17 (a), (b), and (c) are their light-collecting characteristic diagrams, FIG. 18, and FIG.
FIG. 19 is a schematic view of another embodiment of the second invention, and FIG.
Figures (a), (b) and (c) are schematic views of an embodiment of the second invention, Figures 21 (a), (b) and (c) are laser beam waveform diagrams and Figure 22 (a). ), (B), FIGS. 23 (a) and (b) are schematic diagrams of other embodiments, FIG. 24 is a schematic diagram showing a conventional laser device, FIG. 25 is its condensing characteristic diagram, FIG. FIG. 26 is a schematic view showing a conventional laser processing apparatus, FIG. 27 (a),
(B) and (c) are the condensing characteristic diagrams, FIG. 28 is a characteristic diagram showing the relationship between the plate thickness of the workpiece and the cutting speed, and FIG. 29 is a schematic diagram of yet another conventional laser processing apparatus. , Fig. 30 (a),
(B) is its condensing characteristic diagram, FIG. 31, FIG. 32 is a schematic diagram of another conventional laser processing apparatus, FIG. 33 (a), (b), 34
FIGS. (A), (b) and (c) and FIGS. 35 (a) and (b) are light collecting characteristic diagrams, respectively. In the figure, L is a laser resonator, 1 is a total reflection mirror, and 3 is
Is a laser medium, 4 is a convex mirror (exit mirror), 5 is a non-reflective coating film, 7, 7a, 8, 8a, 8b, 8c are laser beams, 9
Is a bent mirror, 10 is a workpiece, 11 is a processed lens, 16 is a condenser lens, and 20 is a partial reflection film. The same reference numerals in the drawings indicate the same or corresponding parts.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masaki Katsuragi 8-1-1 Tsukaguchi Honcho, Amagasaki City, Hyogo Sanryo Electric Co., Ltd. Applied Equipment Research Laboratory (56) Reference JP-A-61-199686 (JP, A) ) JP-A-59-175178 (JP, A) JP-A-59-129485 (JP, A) Actually opened 61-126216 (JP, U) Actually opened 62-17166 (JP, U) Actually opened 52- 122680 (JP, U) Actual public Sho 58-55663 (JP, Y2)

Claims (12)

[Claims] 1. A laser medium, a collimator mirror facing each other with the laser medium sandwiched between them, and a partially transmissive part in the central part and a non-reflective part in the peripheral part, and the laser is directed toward the collimator mirror at the partially transmissive part. A magnifying mirror that magnifies and reflects the beam, and phase difference adjusting means that adjusts and outputs the phase difference between the laser beam that passes through the partially transmitting portion of the magnifying mirror and the laser beam that passes through the non-reflecting portion. A laser processing apparatus comprising: an unstable resonator provided; and a vent mirror that guides an output beam having a phase difference adjusted by the phase difference adjusting means to a workpiece. 2. A laser medium, a collimator mirror facing each other with the laser medium sandwiched between them, and a partially transmissive part in the central part and a non-reflective part in the peripheral part, and the laser is directed toward the collimator mirror at the partially transmissive part. A magnifying mirror that magnifies and reflects the beam, and phase difference adjusting means that adjusts and outputs the phase difference between the laser beam that passes through the partially transmitting portion of the magnifying mirror and the laser beam that passes through the non-reflecting portion. A laser processing apparatus comprising: an unstable resonator provided; and a condensing unit that condenses an output beam having a phase difference adjusted by the phase difference adjusting unit onto a workpiece. 3. The laser processing apparatus according to claim 1, wherein the phase difference adjusting means is configured to adjust the thickness of the partial reflection film provided in the partial transmission part of the magnifying mirror. 4. The phase difference adjusting means is configured such that a reflection film having the same diameter as that of the partial transmission part of the magnifying mirror is provided at the center of the collimator mirror, and the thickness of the reflection film is adjusted. The laser processing apparatus according to item 1 or 2. 5. A structure in which the phase difference adjusting means is provided with a reflection film on the peripheral portion of the collimator mirror except the central portion having the same diameter as the partial transmission portion of the magnifying mirror, and the thickness of the reflection film is adjusted. The laser processing device according to claim 1 or 2. 6. The phase difference adjusting means is configured such that a step portion having the same diameter as that of the partial transmission portion of the magnifying mirror is provided in the central portion of the collimator mirror and the height of the step portion is adjusted. The laser processing apparatus according to item 1 or 2. 7. The phase difference adjusting means comprises a partially transmissive portion and a non-reflective portion of the magnifying mirror as a stepped portion, and the height of the stepped portion is adjusted. The laser processing apparatus according to item 2. 8. The laser processing apparatus according to claim 2, further comprising means for circularly polarizing the output beam having the phase difference adjusted by the phase difference adjusting means. 9. A second beam condensing output beam, the phase difference of which is adjusted by the phase difference adjusting device, in the vicinity of the light collecting device.
The laser processing apparatus according to claim 2, further comprising: 10. The laser processing apparatus according to claim 9, wherein the second condensing means is configured to have a difference between the curvature of the inner surface and the curvature of the outer surface of the magnifying mirror. 11. The laser processing apparatus according to claim 2, further comprising a gas nozzle in which the light converging means is mounted. 12. The laser processing apparatus according to claim 1, wherein the magnifying mirror is a convex or concave mirror.