Laser beam irradiation optical unit and laser processing device

Abstract

To provide an optical unit for laser beam irradiation, and a laser processing device which can obtain an image shape of a spot of a laser beam that appropriately jets molten workpiece and does not leave the workpiece in a cut surface and a hole part, and energy intensity distribution, even when moving speed of the spot of the laser beam is high.SOLUTION: An optical unit for laser beam irradiation for irradiating a processing object with a laser beam emitted from a laser oscillator to form a spot, and subjecting the processing object to laser processing includes an energy intensity distribution adjustment mechanism for adjusting energy intensity distribution of the laser beam at the spot in an irradiation trajectory of the laser beam from the laser oscillator to the processing object, wherein the energy intensity distribution adjustment mechanism adjusts energy intensity distribution of the laser beam at the spot to be ununiform.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a laser beam irradiation optical unit and a laser processing device. [Background technology]

[0002] In recent years, laser beams have been widely used to process a variety of products. By focusing a laser beam at a single point and irradiating it on the workpiece, the surface temperature of the workpiece rises rapidly, melting or evaporating the irradiated surface. Laser processing equipment uses this laser beam to perform processes such as cutting, drilling, and welding on the workpiece. Furthermore, because the laser beam is focused at a single point, precise and fine processing with pinpoint accuracy is possible. Furthermore, by using a higher-energy laser beam, processing time can be shortened and it is possible to process high-hardness workpieces that are difficult to process with blades.

[0003] Here, the image shape of the laser beam at the spot where the laser beam is focused to a single point is circular, and the energy intensity distribution has traditionally been Gaussian or top-hat shaped. However, in laser processing using this conventional spot, when cutting, melting, or drilling a workpiece, the workpiece melted by the laser beam remains on the cut surface or in the hole, resulting in a problem of poor processing quality. Therefore, in recent years, a laser processing method has been proposed in which the image shape of the laser beam at the spot is made annular, allowing the melted workpiece to be appropriately removed and not remain on the cut surface or in the hole.

[0004] For example, when welding two molten zinc steel sheets, by making the image shape of the laser beam at the spot annular, spatter generated during melting will fly in the opposite direction to the incident side of the laser beam at the spot, improving processing quality. Also, when processing highly reflective materials such as aluminum or copper, by making the image shape of the laser beam at the spot annular and the central part of the annular, the workpiece can be melted at the annular part to reduce reflectivity, and cutting and welding can be performed at the central part of the annular part, improving processing quality.

[0005] Therefore, Patent Document 1 discloses an optical system in which a function for shifting the phase of a laser beam is introduced into the optical system, and a phase difference is provided in part of the light flux of the laser beam, so that the image shape of the laser beam at the spot is annular and the energy intensity distribution of the annular laser beam is uniform. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] U.S. Patent No. 9,285,593 Summary of the Invention [Problem to be solved by the invention]

[0007] However, when the image shape of the laser beam at the spot is annular and the energy intensity distribution of the annular laser beam is uniform, if the moving speed of the laser beam spot during laser processing is slow, the molten workpiece is appropriately blown away and does not remain on the cut surface or in the hole, but if the moving speed of the laser beam spot during laser processing is increased, the molten workpiece remains on the cut surface or in the hole, which poses a problem. As a result, there is a problem that the throughput of laser processing cannot be increased.

[0008] The present invention has been made in view of the above circumstances, and aims to provide a laser beam irradiation optical unit and a laser processing device that can obtain an image shape and energy intensity distribution of the laser beam spot that appropriately blasts off the molten workpiece and does not leave any residue on the cut surface or hole, even when the laser beam spot moves at a high speed. [Means for solving the problem]

[0009] In order to solve the above-mentioned problems, as a result of extensive research, the following laser beam irradiation optical unit and laser processing device have been conceived.

[0010] The laser beam irradiation optical unit of the present invention is a laser beam irradiation optical unit for forming a spot on a workpiece with a laser beam irradiated from a laser oscillator and irradiating the spot to perform laser processing, and is equipped with an energy intensity distribution adjustment mechanism that adjusts the energy intensity distribution of the laser beam at the spot within the irradiation trajectory of the laser beam from the laser oscillator to the workpiece, and the energy intensity distribution adjustment mechanism adjusts the energy intensity distribution of the laser beam at the spot so that it becomes non-uniform.

[0011] The laser processing apparatus according to the present invention employs a laser processing head that houses the above-described laser beam irradiation optical unit. [Effects of the Invention]

[0012] The laser beam irradiating optical unit according to the present invention can melt the workpiece in the region in front of the laser beam spot in the direction of movement, even when the laser beam spot moves at a high speed, and can appropriately remove the molten metal from the workpiece in the region behind the spot. This prevents molten material from remaining on the cut surface or in the hole of the workpiece. Furthermore, a laser processing device using the laser beam irradiating optical unit according to the present invention has excellent laser processing quality and high throughput. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a cross-sectional view showing the arrangement of optical elements of a laser beam irradiation optical unit and the approximate trajectory of a laser beam. [Figure 2] 1 is a schematic diagram of the energy intensity distribution in the spot. [Figure 3] 10 is a cross-sectional view of a laser beam irradiation optical unit when adjusting the energy intensity distribution of a laser beam to be non-uniform using a condenser lens. FIG. [Figure 4] 10 is a cross-sectional view of a laser beam irradiation optical unit in which a collimator lens is used to adjust the energy intensity distribution of the laser beam to be non-uniform. FIG. [Figure 5] 10 is a cross-sectional view of a laser beam irradiation optical unit when a laser beam direction adjustment mechanism is used to adjust the energy intensity distribution of the laser beam to be non-uniform. FIG. [Figure 6] FIG. 2 is a schematic cross-sectional view of a laser beam direction adjustment mechanism. [Figure 7] 10 shows the measurement results when the tilt angle in Example 1 is 0°. [Figure 8] 10 shows the measurement results when the tilt angle in Example 1 is 3°. [Figure 9] 10 shows the measurement results when the tilt angle in Example 1 is 3°. [Figure 10] 10 shows the energy distribution in the image shape of the laser beam at a shift of 0.0 mm in Example 2. [Figure 11] 10 shows the energy distribution in the image shape of the laser beam at a shift of 0.125 mm in Example 2. [Figure 12] 10 shows the energy distribution in the image shape of the laser beam at a shift of 1.0 mm in Example 2. [Figure 13] 10 shows the energy distribution in the image shape of the laser beam at a shift of 4.0 mm in Example 2. [Figure 14]10 shows the energy intensity distribution in the Y position direction at the X position of zero when the shift is 0.0 mm in Example 2. [Figure 15] 10 shows the energy intensity distribution in the Y position direction at the X position of zero when the shift is 0.125 mm in Example 2. [Figure 16] 10 shows the energy intensity distribution in the Y position direction at the X position of zero when the shift is 1.0 mm in Example 2. [Figure 17] 10 shows the energy intensity distribution in the Y position direction at the position where the X position is zero when the shift is 4.0 mm in Example 2. [Figure 18] 10 shows the energy distribution in the image shape of the laser beam at a tilt of 0° in Example 3. [Figure 19] 10 shows the energy distribution in the image shape of the laser beam at a tilt of 3° in Example 3. [Figure 20] 10 shows the energy distribution in the image shape of the laser beam at a tilt of 7° in Example 3. [Figure 21] 10 shows the energy intensity distribution in the Y position direction at the X position of zero when the tilt is 0° in Example 3. [Figure 22] 10 shows the energy intensity distribution in the Y position direction at a tilt of 3° in Example 3 where the X position is zero. [Figure 23] 10 shows the energy intensity distribution in the Y position direction at a tilt of 7° in Example 3 where the X position is zero. [Figure 24] 10 shows the energy distribution in the image shape of the laser beam at a shift of 0.0 mm in Example 4. [Figure 25] 10 shows the energy distribution in the image shape of the laser beam at a shift of 0.125 mm in Example 4. [Figure 26] 10 shows the energy distribution in the image shape of the laser beam at a shift of 1.0 mm in Example 4. [Figure 27] 10 shows the energy distribution in the image shape of the laser beam at a shift of 4.0 mm in Example 4. [Figure 28]10 shows the energy intensity distribution in the Y position direction at the X position of zero when the shift is 0.0 mm in Example 4. [Figure 29] 10 shows the energy intensity distribution in the Y position direction at the position where the X position is zero at a shift of 0.125 mm in Example 4. [Figure 30] 10 shows the energy intensity distribution in the Y position direction at the X position of zero when the shift is 1.0 mm in Example 4. [Figure 31] 10 shows the energy intensity distribution in the Y position direction at the position where the X position is zero when the shift is 4.0 mm in Example 4. [Figure 32] 10 shows the energy distribution in the image shape of the laser beam at a tilt of 0° in Example 5. [Figure 33] 10 shows the energy distribution in the image shape of the laser beam at a tilt of 1° in Example 5. [Figure 34] 10 shows the energy distribution in the image shape of the laser beam at a tilt of 4° in Example 5. [Figure 35] 10 shows the energy intensity distribution in the Y position direction at the X position of zero when the tilt is 0° in Example 5. [Figure 36] 10 shows the energy intensity distribution in the Y position direction at a tilt of 1° in Example 5, where the X position is zero. [Figure 37] 10 shows the energy intensity distribution in the Y position direction at a tilt of 4° in Example 5 where the X position is zero. [Figure 38] 10 shows the energy distribution in the image shape of the laser beam at a shift of 0.0 mm in Example 6. [Figure 39] 10 shows the energy distribution in the image shape of the laser beam at a shift of 0.125 mm in Example 6. [Figure 40] 10 shows the energy distribution in the image shape of the laser beam at a shift of 4.0 mm in Example 6. [Figure 41] 10 shows the energy intensity distribution in the Y position direction at the X position of zero when the shift is 0.0 mm in Example 6. [Figure 42]10 shows the energy intensity distribution in the Y position direction at the position where the X position is zero at a shift of 0.125 mm in Example 6. [Figure 43] 10 shows the energy intensity distribution in the Y position direction at the position where the X position is zero when the shift is 4.0 mm in Example 6. [Figure 44] 10 shows the energy distribution in the image shape of the laser beam at a tilt of 0° in Example 7. [Figure 45] 10 shows the energy distribution in the image shape of the laser beam at a tilt of 3° in Example 7. [Figure 46] 10 shows the energy distribution in the image shape of the laser beam at a tilt of 7° in Example 7. [Figure 47] 10 shows the energy intensity distribution in the Y position direction at the X position of zero when the tilt is 0° in Example 7. [Figure 48] 10 shows the energy intensity distribution in the Y position direction at a tilt of 3° in Example 7 where the X position is zero. [Figure 49] 10 shows the energy intensity distribution in the Y position direction at a tilt of 7° in Example 7, where the X position is zero. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the laser beam irradiation optical unit and the laser processing device according to the present invention will be described. Note that the following description merely shows one aspect, and should not be construed as being limited to the following description.

[0015] 1. Laser beam irradiation optical unit The laser beam irradiation optical unit of the present invention is an optical unit for laser beam irradiation that forms a spot on a workpiece with a laser beam irradiated from a laser oscillator and irradiates the spot to perform laser processing, and is equipped with an energy intensity distribution adjustment mechanism that adjusts the energy intensity distribution of the laser beam at the spot within the irradiation trajectory of the laser beam from the laser oscillator to the workpiece, and the energy intensity distribution adjustment mechanism adjusts the energy intensity distribution of the image formed by the laser beam at the spot so that it is non-uniform.

[0016] The energy intensity distribution adjusting mechanism according to the present invention is realized using at least one of a laser beam direction adjusting mechanism, a collimator lens, and a condenser lens.

[0017] The laser beam irradiation optical unit makes the energy intensity distribution of the laser beam uneven at the spot, so that even if the movement speed of the laser beam spot is fast, the workpiece can be melted in the area in front of the spot in the movement direction, and the molten metal of the workpiece can be appropriately scattered in the area behind the spot. This makes it possible to perform laser processing without leaving any molten material on the cut surface or hole of the workpiece.

[0018] The energy intensity distribution adjustment mechanism functions to adjust the energy intensity distribution of the laser beam at the spot to be "non-uniform." Here, excluding transmission losses and reflection losses in the energy intensity distribution adjustment mechanism, the energy intensity distribution adjustment mechanism adjusts the energy intensity distribution of the laser beam to be non-uniform without changing the total energy of the output laser beam relative to the input laser beam. Even if the moving speed of the laser beam spot is fast, the non-uniformity of the energy intensity distribution of the laser beam is not limited as long as the molten workpiece is appropriately removed and does not remain on the cut surface or hole. To give a specific example, the "non-uniform" energy intensity distribution is preferably such that, in the image formed by the laser beam at the spot, the energy intensity of the laser beam is weak in a region ahead of the spot in the direction of movement during laser processing, and the energy intensity of the laser beam is strong in a region behind the spot (opposite the forward region). This is because, even if the moving speed of the laser beam spot is fast, the workpiece can be melted in the region ahead of the spot relative to the moving direction, and the molten metal of the workpiece can be appropriately removed in a region behind the spot.

[0019] The "non-uniform" energy intensity distribution state is not limited to the above, and may be a distribution in which, in the image formed by the laser beam at the spot, the energy intensity of the laser beam is high in a region ahead of the spot in the direction of travel during laser processing and low in a region behind the spot that is different from the region ahead. Furthermore, the energy intensity of the laser beam may be non-uniform in left and right regions in the front-to-back direction of the direction of travel during laser processing, or in front-to-back oblique regions. This is suitable for, for example, butt welding of materials that are both highly reflective and have different melting points, such as aluminum and copper, welding of materials of different thicknesses, or when there is a gap between the materials to be welded.

[0020] 1 shows a cross-sectional view illustrating the arrangement of optical elements in a laser beam irradiation optical unit 1 according to the present invention and the approximate trajectory of a laser beam. The laser beam irradiation optical unit 1 includes a connector 31 for connecting an optical fiber 30 that guides a laser beam output from a laser oscillator, a connector receptacle 32 that fixes the connector 31 relative to the laser beam irradiation trajectory, a collimating lens 21 for collimating the laser beam output in a divergent manner from the output end of the optical fiber 30, a condensing lens 22 for focusing the laser beam collimated by the collimating lens 21 onto a spot on the surface of a workpiece, and an observation device 23 for observing observation light to confirm the intensity distribution of the laser beam at the spot, all of which are arranged in this order from the laser oscillator side along an optical axis 10 of the irradiation trajectory of the laser beam irradiation optical unit 1. The optical centers of the collimating lens 21 and the condensing lens 22 are positioned to coincide with the optical axis 10.

[0021] In FIG. 1, the laser beam direction adjusting mechanism 20, the collimating lens 21, and the condensing lens 22 are arranged along the optical axis 10 in this order from the laser oscillator side, but as long as the energy intensity distribution of the laser beam at the spot can be adjusted to be "ununiform," the laser beam direction adjusting mechanism 20, the condensing lens 22, and the collimating lens 21 may be arranged in this order from the laser oscillator side.

[0022] The laser beam incident from the laser oscillator to the laser beam irradiation optical unit 1 can be any laser beam that can be used for laser processing. In particular, a near-infrared laser beam with an oscillation wavelength of approximately 920 to 1080 nm, such as that of a YAG laser (wavelength 1064 nm), a fiber laser (wavelength 1070 nm), a disk laser (wavelength 1030 nm), or a semiconductor laser (wavelengths 935 nm, 940 nm, 980 nm, 940 to 980 nm, or 940 to 1025 nm), is preferred. Furthermore, the energy distribution of the laser beam incident on the laser beam irradiation optical unit 1 in a plane perpendicular to the optical axis may be Gaussian, with the energy at the center (optical axis portion) being strong, or may be uniform.

[0023] The laser beam direction adjustment mechanism 20 consists of a connector portion 31 to which the optical fiber 30 is connected and a connector receiving portion 32 that fixes the connector portion 31 relative to the optical axis 10 of the irradiation orbit, and adjusts the direction of incidence of the laser beam onto the irradiation orbit by rotating at least one of the connector portion 31 and the connector receiving portion 32 in an arc shape with the center of the core of the optical fiber 30 at the laser beam output end as the center point.

[0024] In FIG. 1 , the connector receptacle 32, the collimating lens 21, and the condenser lens 22 are installed in a lens barrel 33 so that their optical centers coincide with the optical axis 10. An observation tube 34 equipped with an observation device 23 is connected to the lens barrel 33. The observation tube 34 may be detachable from the lens barrel 33. By connecting the detachable observation tube 34 equipped with the observation device 23 to the lens barrel 33 that defines the optical axis 10 of the laser beam irradiation trajectory, it is possible to confirm the direction of incidence of the laser beam onto the irradiation trajectory and the energy intensity distribution of the observation light at the spot when adjusting using the energy intensity distribution adjustment mechanism of the present invention. After observing with the observation device 23 and adjusting the intensity distribution of the laser beam at the spot to a desired one, the observation tube 34 is removed and the surface of the workpiece is positioned where the imaging plane of the observation device 23 was, allowing for accurate laser processing.

[0025] Before the laser beam is incident on the observation device 23, it is preferable to attenuate the intensity of the laser beam to a level that allows observation without damaging the observation device 23. Any attenuation element can be used as long as it attenuates the intensity of the laser beam without distorting the light incident on the observation device 23. It is also preferable to use observation light for observation, called guide light or aiming light, which is different from the laser beam used for processing. This is because the energy intensity of the observation light for observation is not at a level that will damage the observation device 23, and there is no need to attenuate it.

[0026] Preferably, at least one of the collimating lens 21 and the condenser lens 22 of the laser beam irradiation optical unit 1 has a function of converting the image shape of the laser beam at the spot into an annular shape consisting of at least an annular peripheral region (hereinafter referred to as an annular conversion function in this specification). This annular conversion function is different from the function of the energy intensity distribution adjustment mechanism described above, which "adjusts the energy intensity distribution of the laser beam to be non-uniform." Without adjustment of the laser beam by the energy intensity distribution adjustment mechanism, the energy intensity in the annular image shape would be uniform and point-symmetric with respect to the optical axis 10. By converting the energy distribution shape of the spot into an annular shape consisting of at least an annular peripheral region, the laser beam energy is uniformly irradiated on the surface of the workpiece in all directions from the central region of the spot. This allows zinc gas to escape during lap welding of molten zinc steel sheets, resulting in clean welding.

[0027] Furthermore, the shape of the spot produced by the annular transformation function is not particularly limited, and may be, for example, a ring shape and a dotted spot (the dotted spot has a Gaussian shape) in the center of the ring, or a top-hat shape. In this case, it is preferable that the energy intensity of the dotted spot in the center of the ring is higher than the energy intensity of the ring. This is because, for materials with high light reflectivity such as aluminum, the ring-shaped part with low energy intensity can melt the metal to reduce reflectivity, and the center part with high energy intensity can deeply melt the workpiece, making laser processing easier.

[0028] In order to form the image shape of the spot described above, at least one of the optically effective surfaces of the optical element having a ring-shaped transformation function is preferably a diffractive lens, an axicon lens, or an aspheric lens, because the spot shape of the laser beam can be made ring-shaped or comprised of a ring shape and a point shape at the center of the ring shape.

[0029] The laser beam irradiation optical unit 1 does not necessarily have to have a circular conversion function, and a laser beam may be used in which the image shape of the laser beam emitted from the optical fiber 30 is annular, having at least a circular peripheral region. By using a laser beam in which the image shape of the laser beam emitted from the optical fiber 30 is annular, a combination of an annular shape and a dotted shape at the center of the annular shape, or a top hat shape, the laser beam irradiation optical unit 1 can adjust the energy intensity distribution in the image shape of the laser beam to be non-uniform. Hereinafter, an embodiment will be described in which at least one of the collimator lens 21 and the condenser lens 22 has a circular conversion function, but the laser beam irradiation optical unit 1 is not limited to one having a circular conversion function.

[0030] Next, the energy intensity distribution at the spot when the image shape of the laser beam at the spot is annular will be described with reference to FIG. 2. FIG. 2(a) shows the energy intensity distribution of the laser beam at the spot when the energy intensity distribution in a plane perpendicular to the optical axis of the laser beam irradiated from the laser oscillator is Gaussian, the image shape of the laser beam at the spot is annular due to the use of a circular transformation function, and the energy intensity distribution of the laser beam is not adjusted to be non-uniform using the energy intensity distribution adjustment mechanism. The horizontal axis represents the coordinate on a line perpendicular to the optical axis including the optical axis at the spot, and the direction from the positive side (right) to the negative side (left) of the coordinate represents the direction of travel of the spot during laser processing. That is, the first quadrant of FIG. 2(a) corresponds to the rear region in the direction of travel of laser processing, and the second quadrant corresponds to the front region. The center of the horizontal axis indicates the position of the optical axis of the laser beam irradiation optical unit 1. The vertical axis represents the energy intensity of the laser beam. The dashed line in FIG. 2 indicates the peak value of the energy intensity in FIG. 2(a). That is, if the energy intensity distribution is not adjusted non-uniformly by the energy intensity distribution adjusting mechanism, the energy intensity distribution of the laser beam will have a uniform bimodal shape with peak values ​​in the front and rear regions.

[0031] Next, Figure 2(b) shows the energy intensity distribution of the laser beam at the spot when the energy intensity distribution of the laser beam in the state shown in Figure 2(a) is adjusted to be nonuniform using the energy intensity distribution adjustment mechanism. As in Figure 2(a), the first quadrant in Figure 2(b) corresponds to the rear region in the direction of laser processing, and the second quadrant corresponds to the front region. Figure 2(b) shows the state in which the energy intensity distribution is adjusted to be nonuniform by biasing the energy toward the rear region. In this case, the energy intensity in the front region in the direction of laser processing is weak, while the energy intensity in the rear region is strong. In other words, the energy intensity distribution of the laser beam has a "nonuniform bimodal" peak value in the front and rear regions. Note that the energy intensity distribution adjustment mechanism does not change the total energy of the output laser beam relative to the input laser beam, so the total energy of the laser beam shown in Figure 2(a) and Figure 2(b) (the integrated value of the energy on the horizontal axis) is nearly identical.

[0032] When the laser beam spot has a circular image shape and a uniform bimodal energy intensity distribution, as shown in Figure 2(a), the melted workpiece is properly removed and does not remain on the cut surface or hole when the laser beam spot is moved slowly during laser processing. However, when the laser beam spot is moved quickly during laser processing, the melted workpiece remains on the cut surface or hole. However, when the laser beam spot is moved quickly during laser processing, the melted workpiece remains on the cut surface or hole. However, when the laser beam spot has a circular image shape and a non-uniform bimodal shape, as shown in Figure 2(b), the workpiece melted in the front region of the spot can be properly removed in the rear region of the spot, where the energy intensity is strong, even when the laser beam spot is moved quickly during laser processing. This prevents the melted workpiece from remaining on the cut surface or hole.

[0033] In the non-uniform energy intensity distribution of the laser beam in FIG. 2(b), when the peak value of the strong energy intensity in the rear region (first quadrant) in the direction of travel of the spot during laser processing is set to 1, the peak value of the weak energy intensity in the front region (second quadrant) is preferably 0.1 or more and 0.95 or less. As described above, this is because laser beams with weak energy intensity and laser beams with strong energy intensity distributions can each play different roles in laser processing, such as melting a workpiece with a laser beam with a weak energy intensity distribution and blowing away the molten metal from the workpiece with a laser beam with a strong energy intensity distribution. Note that when the peak value of the strong energy intensity is set to 1, the lower limit of the peak value of the weak energy intensity is more preferably 0.20, and even more preferably 0.25. When the peak value of the strong energy intensity is set to 1, the upper limit of the peak value of the weak energy intensity is more preferably 0.6, and even more preferably 0.5. Note that the comparison of the laser beam energy intensity intensity ratio in Figure 2(b) is made with the peak values ​​of the energy intensity distribution that form each peak in the "non-uniform bimodal" shape, and the center of the spot (the center of the horizontal axis in Figure 2(b)) is not included.

[0034] Furthermore, the energy intensity distribution in the forward and rearward regions relative to the direction of laser processing may be non-uniform, i.e., the energy intensity ratio in the non-uniform energy intensity distribution of the annular portion is preferably such that, when the peak value of the strong energy intensity in the forward region in the direction of laser processing of the spot is 1, the peak value of the weak energy intensity in the rearward region is 0.1 or more and 0.95 or less. This is because a laser beam with a weak energy intensity and a laser beam with a strong energy intensity distribution can each play different roles in laser processing. Note that, when the peak value of the strong energy intensity is 1, the lower limit of the peak value of the weak energy intensity is more preferably 0.20, and even more preferably 0.25. When the peak value of the strong energy intensity is 1, the upper limit of the peak value of the weak energy intensity is more preferably 0.6, and even more preferably 0.5.

[0035] [First embodiment of energy intensity distribution adjustment mechanism] FIG. 3 shows a cross-sectional view of a laser beam irradiation optical unit 2 according to a first embodiment of the energy intensity distribution adjustment mechanism, in which the energy intensity distribution of a laser beam is adjusted to be non-uniform using a condenser lens 22a and a condenser lens 22b. The condenser lens 22a with an annular conversion function shown in FIG. 3(a) is in a state in which the condenser lens 22a is moved in a direction parallel to a plane perpendicular to the optical axis 10 (above the optical axis 10 in FIG. 3(a)). Hereinafter, in this specification, moving an optical element in a direction parallel to a plane perpendicular to the optical axis 10 is referred to as a "shift." In this case, the optical center of the condenser lens 22a is located above the optical axis 10 in the drawing. In the state shown in FIG. 3(a), the curvature distribution of the surface of the condenser lens 22a differs between the laser beam passing through the lower half of the condenser lens 22a relative to the optical axis 10 and the laser beam passing through the upper half. As a result, decentering coma aberration occurs in the laser beam passing through the condenser lens 22a in the direction of the meridional plane. In this way, the energy intensity distribution of the laser beam at the spot can be adjusted to be "non-uniform." The degree of non-uniformity can be adjusted by the amount of shift of the condenser lens 22a.

[0036] The focusing lens 22b with an annular transformation function shown in FIG. 3(b) is rotated around a line perpendicular to the optical axis 10 and including the optical center of the focusing lens 22b. Hereinafter, in this specification, rotating an optical element around a line perpendicular to the optical axis 10 and including the optical center on the optical axis 10 is referred to as tilting. In this case, the position of the optical center of the focusing lens 22b coincides with the optical axis 10. In the state shown in FIG. 3(b), the normal incidence angles of the laser beam passing through the upper half of the focusing lens 22b relative to the optical axis 10 and the laser beam passing through the lower half are asymmetric. This causes decentering coma aberration in the direction of the meridional plane in the laser beam passing through the focusing lens 22b. In this way, the energy intensity distribution of the laser beam at the spot can be adjusted to be "non-uniform." The degree of non-uniformity can be adjusted by the amount of tilt of the condenser lens 22b.

[0037] The condenser lens 22a can be shifted, for example, by using a lens holder that secures the condenser lens 22a and that has a function that allows it to be shifted perpendicular to the optical axis, and by shifting the position of the lens holder by pushing it in with a screw, etc. The condenser lens 22b can be tilted, for example, by using a lens holder that secures the condenser lens 22b and that has a function that allows it to be tilted around a line including the optical center as the axis of rotation, and by pushing it in with a screw, etc. Note that the above methods are not limited to the above, as long as the condenser lens 22a can be shifted or the condenser lens 22b can be tilted. The energy intensity distribution of the laser beam at the spot can be adjusted to an appropriate "non-uniform" state by adjusting the shift amount of the condenser lens 22a or the tilt amount of the condenser lens 22b while observing the energy intensity distribution at the spot with the observation device 23 described above.

[0038] In the above-described laser beam irradiation optical unit 2, the annular conversion function has been described as being provided by the condenser lenses 22a and 22b. However, the annular conversion function may also be provided by optical elements other than the condenser lenses 22a and 22b. For example, the collimator lens 21 may also be provided with the annular conversion function. Even in this case, the energy intensity distribution of the laser beam at the spot can be adjusted to an appropriate "non-uniform" state by adjusting the shift amount of the condenser lens 22a or the tilt amount of the condenser lens 22b, as described above. In this case, it is preferable to adjust the tilt amount to adjust the energy intensity distribution of the laser beam at the spot to an appropriate "non-uniform" state.

[0039] [Second embodiment of energy intensity distribution adjustment mechanism] Next, FIG. 4 shows a cross-sectional view of a laser beam irradiation optical unit 3 in which a second embodiment of the energy intensity distribution adjustment mechanism is used to adjust the energy intensity distribution of a laser beam to be non-uniform using collimating lenses 21a and 21b. The collimating lens 21a with an annular conversion function shown in FIG. 4(a) is shifted in a direction parallel to a plane perpendicular to the optical axis 10 (in FIG. 4(a), the collimating lens 21a is shifted above the optical axis 10). In this case, the optical center of the collimating lens 21a is located above the optical axis 10. In the state shown in FIG. 4(a), the curvature distribution of the surface of the collimating lens 21a differs between the laser beam passing through the lower half of the collimating lens 21a below the optical axis 10 and the laser beam passing through the upper half. As a result, decentering coma aberration occurs in the laser beam passing through the collimating lens 21a in the direction of the meridional plane. In this way, the energy intensity distribution of the laser beam at the spot can be adjusted to be "non-uniform." The degree of non-uniformity can be adjusted by the amount of shift of the collimator lens 21a.

[0040] The collimating lens 21b with an annular transformation function shown in FIG. 4(b) is tilted around a line on the optical axis 10 that includes the optical center of the collimating lens 21b. In this case, the position of the optical center of the collimating lens 21b coincides with the optical axis 10. In the state shown in FIG. 4(b), the normal incidence angles of the laser beam passing through the upper half of the collimating lens 21b relative to the optical axis 10 and the laser beam passing through the lower half are asymmetrical. This causes decentering coma aberration in the direction of the meridional plane in the laser beam passing through the collimating lens 21b. In this way, the energy intensity distribution of the laser beam at the spot can be adjusted to be "non-uniform." The degree of non-uniformity can be adjusted by the amount of tilt of the collimating lens 21b.

[0041] The collimator lens 21a can be shifted, for example, by using a lens holder that secures the collimator lens 21a and that has the ability to shift the lens holder perpendicular to the optical axis, and by pushing the lens holder in with a screw, or by other means. The collimator lens 21b can be tilted by using a lens holder that secures the collimator lens 21b and that has the ability to tilt the lens holder around a line including the optical center as a rotation axis, and by pushing the lens holder in with a screw, or by other means. Note that the above methods are not limited to the above, as long as the collimator lens 21a or the collimator lens 21b can be shifted or tilted. The energy intensity distribution of the laser beam at the spot can be adjusted to an appropriate "non-uniform" state by adjusting the shift amount of the collimator lens 21a or the tilt amount of the collimator lens 21b while observing the energy intensity distribution at the spot with the observation device 23.

[0042] In the above-described laser beam irradiation optical unit 3, the annular conversion function has been described as being provided by the collimator lenses 21a and 21b. However, the annular conversion function may be provided by optical elements other than the collimator lenses 21a and 21b. For example, the condenser lens 22 may also be provided with the annular conversion function. Even in this case, the energy intensity distribution of the laser beam at the spot can be adjusted to an appropriate "non-uniform" state by adjusting the shift amount of the collimator lens 21a or the tilt amount of the collimator lens 21b, as described above. In this case, it is preferable to adjust the tilt amount to adjust the energy intensity distribution of the laser beam at the spot to an appropriate "non-uniform" state.

[0043] [Third embodiment of energy intensity distribution adjustment mechanism] Next, FIG. 5 shows a cross-sectional view of a laser beam irradiation optical unit 4 in a third embodiment of the energy intensity distribution adjustment mechanism, in which the laser beam direction adjustment mechanism 20 is used to adjust the energy intensity distribution of the laser beam to be non-uniform. The laser beam direction adjustment mechanism 20a in FIG. 5(a), which is composed of a connector portion 31a and a connector receptacle portion 32a, is in a state in which the entire laser beam direction adjustment mechanism 20 is shifted in a direction parallel to a plane perpendicular to the optical axis 10 (in FIG. 5(a), above the optical axis 10). The optical fiber 30a is fixed to the connector portion 31a. In this case, the optical center of the laser beam direction adjustment mechanism 20a is located above the optical axis 10 in the drawing. In the state shown in FIG. 5(a), the curvature distributions of the surfaces of the collimating lens 21 and the condensing lens 22 are different between the laser beam passing through the lower half of the optical axis 10 of the collimating lens 21 and the condensing lens 22 and the laser beam passing through the upper half. In other words, the image formed on the spot has decentering coma aberration in the direction of the meridional plane. In this way, the energy intensity distribution of the laser beam on the spot can be adjusted to be "non-uniform." The degree of non-uniformity can be adjusted by the amount of shift of the laser beam direction adjustment mechanism 20a.

[0044] The laser beam direction adjustment mechanism 20b in FIG. 5(b) is in a state in which the connector portion 31b, to which the optical fiber 30b is fixed, is tilted downward in FIG. 5(b) relative to the connector receptacle 32b using the "arc-shaped rotation" function of the laser beam direction adjustment mechanism 20. Details of this "arc-shaped rotation" function will be described later. In this case, the optical center of the connector receptacle 32b is aligned with the optical axis 10. Note that, in this description, it is assumed that the emission direction of the laser beam output from the output end of the optical fiber 30b is aligned with the reference optical axis determined by the structure of the output end of the optical fiber 30b and the structure of the connector portion 31b. In the state shown in FIG. 5(b), the normal incidence angles of the laser beam passing through the upper half of the collimating lens 21 and the condensing lens 22 relative to the optical axis 10 are asymmetric with respect to the surfaces of the collimating lens 21 and the condensing lens 22. As a result, decentering coma aberration occurs in the direction of the meridional plane in the laser beam passing through the collimator lens 21 and the condenser lens 22. In this way, the energy intensity distribution of the laser beam at the spot can be adjusted to be "non-uniform." The degree of non-uniformity can be adjusted by the tilt amount of the laser beam direction adjustment mechanism 20b, i.e., the amount of rotation in an arc.

[0045] One method for shifting the laser beam direction adjustment mechanism 20a is to use a holder that secures the laser beam direction adjustment mechanism 20a and that has the ability to shift the mechanism perpendicular to the optical axis, and then shift the position of the holder by, for example, pushing it in with a screw. The "arc-shaped rotation" function of the laser beam direction adjustment mechanism 20b will be described later. Note that the method is not limited to the above, as long as the laser beam direction adjustment mechanism 20a can be shifted or the laser beam direction adjustment mechanism 20b can be tilted. Then, by adjusting the shift amount of the laser beam direction adjustment mechanism 20a or the tilt amount of the laser beam direction adjustment mechanism 20b while observing the energy intensity distribution at the spot with the observation device 23, the energy intensity distribution of the laser beam at the spot can be adjusted to an appropriate "non-uniform" state.

[0046] In the above-described laser beam irradiation optical unit 4, the collimator lens 21 has a circular conversion function, but the circular conversion function can be provided to at least one of the collimator lens 21 and the condenser lens 22. In either case, the energy intensity distribution of the laser beam at the spot can be adjusted to an appropriate "non-uniform" state by adjusting the shift amount of the laser beam direction adjustment mechanism 20a or the tilt amount of the laser beam direction adjustment mechanism 20b that uses the "arc-shaped rotation" function. In order to adjust the energy intensity distribution of the laser beam at the spot to an even more appropriate "non-uniform" state, it is preferable to adjust the tilt amount.

[0047] As described in the first to third embodiments of the energy intensity distribution adjustment mechanism, the energy intensity distribution adjustment mechanism of the present invention can be realized using at least one of the laser beam direction adjustment mechanism 20, the collimator lens 21, and the focusing lens 22.

[0048] [Laser beam direction adjustment mechanism] 6 shows a schematic cross-sectional view of the optical fiber 30 and the laser beam direction adjustment mechanism 20. The laser beam direction adjustment mechanism 20 has the function of adjusting the incident direction of the laser beam onto the irradiation trajectory to an appropriate direction even if the emission direction of the laser beam output from the output end of the optical fiber 30 is tilted. This adjustment is performed using the "arc-shaped rotation" function of the laser beam direction adjustment mechanism 20. The tilt operation in the third embodiment of the energy intensity distribution adjustment mechanism according to the present invention utilizes this "arc-shaped rotation" function of the laser beam direction adjustment mechanism 20.

[0049] The function of the laser beam direction adjustment mechanism 20 to adjust the incident direction of the laser beam onto the irradiation trajectory to an appropriate direction will now be described. A laser beam output from a laser oscillator is guided to a laser processing head of a laser processing device using an optical fiber 30. This optical fiber 30 is connected to a laser beam irradiation optical unit 1 in the laser processing head via a connector 31. As shown in FIG. 6( a), the emission direction 11 of the laser beam output from the output end of the optical fiber 30 has a certain range of inclination, represented by an angle θ, with the center of the optical fiber output end as the center point, relative to a reference optical axis (which coincides with the optical axis 10 of the irradiation trajectory) determined by the structure of the output end of the optical fiber 30 and the structure of the connector 31. Specifically, for example, in a CW fiber laser from Raycus Fiber, the angle of the optical axis of the laser beam output from the output end of the optical fiber relative to the reference optical axis determined by the structure of the output end of the optical fiber and the structure of the connector is set to 30 mrad (milliradians) or less.

[0050] FIG. 6(b) is a cross-sectional view showing an overview of the adjustment of the incident direction of the laser beam output from the output end of the optical fiber 30 onto the irradiation orbit using the laser beam direction adjustment mechanism 20. In FIG. 6(b), the laser beam direction adjustment mechanism 20 is used to rotate the optical fiber 30 and the connector unit 31 side in an arc of radius r at an angle of −θ, with the center of the optical fiber output end as the center point. The rotation trajectory 40 shows the trajectory when the connector unit 31 rotates in an arc of radius r. That is, the reference optical axis 12, determined by the structure of the output end of the optical fiber 30 and the structure of the connector unit 31, is angled by −θ with respect to the optical axis 10 of the irradiation orbit. This adjustment causes the emission direction 11 of the laser beam output from the output end of the optical fiber 30 to be substantially aligned with the optical axis 10 of the irradiation orbit.

[0051] In this case, it is preferable that the laser beam direction adjustment mechanism 20 has a structure that rotates in an arc around the center of the output end of the optical fiber 30 of the laser oscillator. By having the laser beam direction adjustment mechanism 20 have a structure in which at least one of the connector portion 31 and the connector receiving portion 32 rotates in an arc around the center of the core of the optical fiber 30 at the laser beam output end, it is possible to adjust the incident direction of the irradiation trajectory of the laser beam output from the output end of the optical fiber relative to the reference optical axis 12 determined by the structure of the output end of the optical fiber 30 and the structure of the connector portion 31 so that it substantially coincides with the optical axis 10 of the irradiation trajectory of the laser beam of the laser beam irradiation optical unit 1.

[0052] In the laser beam direction adjustment mechanism 20, the range of the rotation angle θ of the circular arc rotation centered on the central part of the output end of the optical fiber 30 is preferably −30 mrad<θ<30 mrad, when the direction of the optical axis 10 passing through the optical center of the optical element of the irradiation orbit is set to 0 mrad. This is because, even if there is an inclination of the emission direction 11 of the laser beam output from the output end of the optical fiber 30 with respect to the reference optical axis 12 determined by the structure of the output end of the optical fiber 30 and the structure of the connector part 31, the incident direction of the laser beam of the laser beam irradiation optical unit 1 onto the irradiation orbit can be adjusted to substantially coincide with the optical axis 10 of the irradiation orbit, and the tilt operation in the third embodiment of the energy intensity distribution adjustment mechanism can be performed.

[0053] In addition, the rotation angle θ of the arc-shaped rotation with the center point being the center of the output end of the optical fiber 30 mentioned above indicates an angle in any plane in a plane containing the optical axis 10 of the irradiation orbit along the optical axis 10 of the irradiation orbit, and is not limited to an angle in a specific plane.

[0054] The rotation mechanism of the laser beam direction adjustment mechanism 20 is, for example, on a plane perpendicular to the optical axis 10 and has an X-direction rotation axis and a Y-direction rotation axis which are perpendicular to each other, thereby enabling rotation in an arc shape around the center point of the center of the output end of the optical fiber 30. However, the rotation mechanism is not limited to the above, as long as it can adjust the rotation angle θ of the arc shape around the center point of the center of the output end of the optical fiber 30 within the range of −30 mrad<θ<30 mrad with respect to the optical axis 10 of the irradiation orbit on any plane including the optical axis 10 of the irradiation orbit along the optical axis 10 of the irradiation orbit.

[0055] [Observation equipment] The observation device 23 is not particularly limited, and any observation device can be used as long as it can observe the irradiation position of the laser beam and the energy intensity distribution of the laser beam adjusted using the energy intensity distribution adjustment mechanism of the present invention. The observation tube 34 equipped with the observation device 23 is preferably detachable from the lens barrel 33. When the observation tube 34 is connected to the lens barrel 33, the position of the imaging plane (observation point) of the observation device 23 is preferably located at the same location as the surface of the workpiece where the spot is formed during laser processing. Furthermore, the center of the imaging plane of the observation device 23 is preferably located on the optical axis 10 and at the center of the processed portion of the workpiece. This is because the position of the laser beam and the energy distribution of the laser beam can be observed at the same location as the surface of the workpiece where the spot is formed. After adjusting the energy intensity distribution of the laser beam at the spot to an appropriate "non-uniform" state, the observation device 23 is removed and the workpiece can be processed by placing the surface of the workpiece at the position of the imaging plane of the observation device 23.

[0056] [Collimating lens] The collimating lens 21 is an optical element for converting the laser beam radially output from the output end of the optical fiber 30 into parallel light.

[0057] [Condenser lens] The condenser lens 22 is an optical element for condensing the laser beam converted into parallel light by the collimator lens 21 into a spot.

[0058] [Method for adjusting energy intensity distribution] A specific method for adjusting the energy intensity distribution of the laser beam in the spot to an appropriate "non-uniform" state will be described below using the first to third embodiments of the energy intensity distribution adjusting mechanism of the laser beam irradiation optical unit 1. Note that this adjustment method is not limited to the methods described below.

[0059] Here, we will explain the case where the laser beam image on the surface of the workpiece has a ring-shaped shape. From the laser beam spot image captured by the observation device 23, the energy intensity distribution on a first coordinate axis that includes the center of the imaging plane and is in the direction of the spot's travel during laser processing is extracted. Then, with the center of the imaging plane as the origin of the first coordinate axis, the energy intensity distribution values ​​on the minus and plus coordinate sides of the first coordinate axis are integrated to define EM1 and EP1. Similarly, the energy intensity distribution on a second coordinate axis that is perpendicular to the first coordinate axis is extracted, and with the center of the imaging plane as the origin of the second coordinate axis, the energy intensity distribution values ​​on the minus and plus coordinate sides of the second coordinate axis are integrated to define EM2 and EP2. By comparing the magnitudes of EM1, EP1, EM2, and EP2, the energy intensity distribution of the spot image on the coordinate plane consisting of the first and second coordinate axes can be determined.

[0060] Furthermore, peak values ​​of energy intensity values ​​on the minus coordinate side and the plus coordinate side on the first coordinate axis and the second coordinate axis are extracted from the laser beam spot image captured by the observation device 23. From these peak values ​​of energy intensity values ​​and the coordinate values ​​that indicate the peak values, it is possible to know the non-uniformity of the shape of the energy intensity distribution in the direction of spot travel and the strength ratio of the energy intensity.

[0061] Based on the energy intensity distribution information of the laser beam in the spot thus confirmed, any of the first to third embodiments of the energy intensity distribution adjustment mechanism can be used to adjust the energy intensity distribution of the laser beam in the spot to an appropriate "non-uniform" state. After adjustment, the energy intensity distribution of the laser beam in the spot can be confirmed again using the method described above, and the completion of adjustment can be determined based on criteria such as the energy intensity distribution state obtained by comparing the magnitudes of EM1, EP1, EM2, and EP2, or whether the difference in peak values ​​between the front and rear regions in the direction of spot travel is within the allowable range of the energy intensity intensity ratio. If the adjustment fails to meet the criteria in one adjustment, it can be readjusted using the method described above. In this way, an appropriate energy distribution can be obtained in the spot.

[0062] In the first to third embodiments of the energy intensity distribution adjusting mechanism, when the energy intensity distribution of the laser beam at the spot is adjusted to an appropriate non-uniform state, the center position of the front and rear regions of the image at the spot (spot center position) may deviate from the position of the optical axis. In this case, by adjusting the energy intensity distribution of the laser beam at the spot to an appropriate non-uniform state and then measuring the deviation of the spot center position from the optical axis 10, the spot center position can be correctly aligned with the processing position of the workpiece during laser processing.

[0063] Furthermore, as described above, since the energy intensity distribution at the spot can be obtained as numerical information from the observation device 23, it is possible to automate the adjustment by, for example, having the control device of the laser beam irradiation optical unit 1 learn the above-mentioned observation values ​​obtained from the observation device 23 in advance according to the magnitude of adjustment by the energy intensity distribution adjustment mechanism.

[0064] 2. Laser processing equipment The laser processing apparatus according to the present invention is obtained by accommodating the above-described laser beam irradiation optical unit 1 in a laser processing head of the laser processing apparatus. This allows a laser beam to be irradiated onto a workpiece, thereby processing the workpiece by heating and melting it. Furthermore, the laser processing apparatus according to the present invention can adjust the energy intensity distribution of the laser beam at the spot to an appropriate "non-uniform" state using the first to third embodiments of the energy intensity distribution adjustment mechanism, which uses at least one of the laser beam direction adjustment mechanism 20, the collimator lens 21, and the condenser lens 22. This "non-uniformity" can be a distribution in which the energy intensity of the laser beam is weak in a forward region of the spot in the direction of travel during laser processing, with the boundary being a line perpendicular to the optical axis and including the optical axis of the spot, and strong in a rear region different from the forward region.

[0065] Therefore, even if the laser beam spot moves at a high speed, the laser processing device melts the workpiece in the area in front of the spot in the direction of movement, and appropriately blasts off the molten metal of the workpiece in the area behind the spot so that it does not remain on the cut surface or hole.

[0066] The embodiment of the present invention described above is one aspect of the present invention, and can be modified as appropriate without departing from the spirit of the present invention. In addition, the present invention will be described in more detail below using examples, but the present invention is not limited to the following examples. [Example]

[0067] The laser beam irradiation optical unit in Example 1 was an optical system according to the third embodiment of the energy intensity distribution adjustment mechanism shown in FIG. 5(b). A single-mode fiber laser YLS-6000 (manufactured by IPG Photonics) with a laser beam wavelength of 1070 nm was used as the laser oscillator. Because it was a single-mode laser, the energy intensity distribution at the spot was Gaussian. The laser beam output from this YLS-6000 was connected to a connector 31b via an optical fiber 30b. The direction of the laser beam emitted from the optical fiber 30b was approximately aligned with the optical axis 10. A lens with a focal length of 200 mm was used as the collimating lens 21 with a circular conversion function. Furthermore, a lens with a focal length of 200 mm and an aspherical surface was used as the focusing lens 22. A FocusMonitor FM+ (manufactured by PRIMES) was used as the observation device 23. Then, along the optical axis of the optical system of Example 1, a laser beam direction adjusting mechanism 20b, a collimating lens 21, a condensing lens 22, and an observation device 23 were arranged in this order from the laser oscillator side.

[0068] Measurements were then performed using the YLS-6000 with an output of 600 W and LaserDiagnose Software (PRIMES) and FocusMonitor FM+. Figure 7 shows the measurement results when the tilt angle using the "arc rotation" function of the laser beam direction adjustment mechanism 20b was 0°. The X-intensity contour line in Figure 7 represents the energy intensity distribution of the spot at any coordinate on a plane perpendicular to the optical axis of the optical system of Example 1. The horizontal axis (X-axis) represents the coordinate whose center coincides with the position of the optical axis, and the vertical axis represents the energy intensity (higher energy at the top). The Y-intensity contour line represents the energy intensity distribution of the spot at coordinates perpendicular to the coordinate system of the X-intensity contour line. The vertical axis (Y-axis) represents the coordinate whose center coincides with the position of the optical axis, and the horizontal axis represents the energy intensity (higher energy at the right). The XY contour line is a plot of the area on the plane formed by the coordinates of the X and Y axes where the laser beam has the same energy intensity as the arrow in the Y Intensity contour line (peak value of energy intensity in Figure 7). The horizontal direction is the X axis, the vertical direction is the Y axis, and the center of the XY contour line is the origin of each axis. In this case, the diameter of the ring indicating the peak value of the spot was approximately 0.43 mm. The energy intensity of the arrow in the Y Intensity contour line was 688.42 kW / cm. 2 It was.

[0069] Next, the measurement results when the tilt angle using the "arc-shaped rotation" function of the laser beam direction adjustment mechanism 20b is 3° are shown in Figures 8 and 9. The information displayed in Figures 8 and 9 is the same as that explained in Figure 7, except that the XY contour line in Figure 8 depicts the area where a laser beam with the same intensity as the energy intensity indicated by the arrow in the Y intensity contour line diagram of Figure 8 exists, and the XY contour line in Figure 9 depicts the area where a laser beam with the same intensity as the energy intensity indicated by the arrow in the Y intensity contour line diagram of Figure 9 exists. From the Y intensity contour line diagrams in Figures 8 and 9, it was confirmed that the energy intensity distribution of the laser beam at the spot in the Y-axis direction could be adjusted to be "non-uniform" by tilting the laser beam direction adjustment mechanism 20b using the "arc-shaped rotation" function.

[0070] The energy intensity at the arrow in the Y Intensity contour line diagram in Figure 8 is 396.28 kW / cm 2 The energy intensity at the arrow in the Y Intensity contour line diagram in Figure 9 is 810.61 kW / cm 2 In other words, it was confirmed that the energy intensity on the strong energy intensity side after adjusting the energy intensity to "non-uniform" was greater than the energy intensity before adjusting to "non-uniform". This confirmed that even if the energy intensity distribution of the laser beam was adjusted to be non-uniform, the energy intensity distribution adjusting mechanism (laser beam direction adjusting mechanism in Example 1) did not change the total energy of the output laser beam relative to the input laser beam. [Example]

[0071] The laser beam irradiation optical unit of Example 2 was an optical system of the first embodiment of the energy intensity distribution adjustment mechanism shown in FIG. 3(a). The optical system used included a connector 31 connecting an optical fiber 30 that guides a laser beam having a Gaussian (single-mode) energy intensity distribution output from a laser oscillator, a connector receptacle 32 that fixes the connector 31 relative to the laser beam irradiation trajectory, a collimating lens 21 with a focal length of 200 mm that collimates the laser beam output from the output end of the optical fiber 30, and a focusing lens 22a with a focal length of 200 mm and an aspherical surface that has a circular conversion function to focus the laser beam collimated by the collimating lens 21 onto a spot on the surface of the workpiece. The laser beam direction adjustment mechanism 20, the collimating lens 21, the focusing lens 22a, and an observation device 23 were arranged, in order from the laser oscillator side, along the optical axis of the optical system of Example 2. The observation device 23, which observes the observation light to confirm the laser beam intensity distribution at the spot, was used as the observation point during the optical simulation.

[0072] A laser beam with a wavelength of 1070 nm was then set to enter the connector portion 31 from the optical fiber 30, and a simulation was performed using the optical simulator Zemax OpticStudio (manufactured by Zemax, LLC). Figures 10-17 show the simulation results of the energy intensity distribution at the spot when the focusing lens 22a was shifted by 0.0 mm, 0.125 mm, 1.0 mm, and 4.0 mm. Figures 10-13 show the energy distribution in the image shape of the laser beam formed on the imaging surface of the observation device 23. The negative side of the Y position on the vertical axis corresponds to the forward region during laser processing, and the positive side corresponds to the backward region. The X position on the horizontal axis represents the coordinate perpendicular to the vertical axis. The relative ratio of the energy intensity at this time is indicated by the shade of color. Figures 14-17 also show the energy intensity distribution in the Y position direction at the X position of zero in Figures 10-13. The horizontal axis represents the Y position, and the vertical axis represents the energy intensity of the laser beam.

[0073] 10 to 13, it was confirmed by the change in color intensity that the energy intensity distribution changed from uniform to non-uniform while maintaining the annular shape by shifting the condenser lens 22a by 0.0 mm, 0.125 mm, 1.0 mm, and 4.0 mm. Furthermore, as shown in Figures 14 to 17, the energy intensity ratio between the front and rear regions, when the energy intensity in the rear region is set to 1.0, is 1.0 when shifted by 0.0 mm, but is 0.87 when shifted by 0.125 mm, 0.48 when shifted by 1.0 mm, and 0.10 when shifted by 4.0 mm. [Example]

[0074] The laser beam irradiation optical unit of Example 3 had the same configuration as Example 2, except that the optical system of the first embodiment of the energy intensity distribution adjustment mechanism shown in Figure 3(b) was selected and the same lens as the focusing lens 22a of Example 2 was used as the focusing lens 22b.

[0075] A laser beam with a wavelength of 1070 nm was then set to enter the connector portion 31 from the optical fiber 30, and a simulation was performed using the optical simulator Zemax OpticStudio (manufactured by Zemax, LLC). Figures 18-23 show the simulation results of the energy intensity distribution at the spot when the tilt angle of the condenser lens 22b was 0°, 3°, and 7°. Figures 18-20 show the energy distribution in the image shape of the laser beam formed on the imaging surface of the observation device 23, with the negative side of the Y position on the vertical axis corresponding to the forward region during laser processing and the positive side corresponding to the backward region. The X position on the horizontal axis represents the coordinate perpendicular to the vertical axis. The relative ratio of the energy intensity at this time is indicated by the shade of color. Figures 21-23 also show the energy intensity distribution in the Y position direction when the X position in Figures 18-20 is zero, with the horizontal axis representing the Y position and the vertical axis representing the energy intensity of the laser beam.

[0076] 18 to 20, by setting the tilt angle of the condenser lens 22b to 0°, 3°, and 7°, it was confirmed by the change in color intensity that the energy intensity distribution changed from uniform to non-uniform while maintaining the annular image shape. Furthermore, from Figures 21 to 23, it was confirmed that the energy intensity ratio in the front region and the rear region, when the energy intensity in the rear region was set to 1.0, was 1.0 at a tilt of 0°, 0.85 at a tilt of 3°, and 0.59 at a tilt of 7°. [Example]

[0077] For the laser beam irradiation optical unit of Example 4, an optical system according to the second embodiment of the energy intensity distribution adjustment mechanism shown in Fig. 4(a) was selected. Here, an aspherical lens with a focal length of 200 mm and equipped with a circular conversion function was used as the collimator lens 21a, and a lens with a focal length of 200 mm was used as the condenser lens 22. Then, from the laser oscillator side, the laser beam direction adjustment mechanism 20, the collimator lens 21a, the condenser lens 22, and the observation device 23 were arranged along the optical axis of the optical system of Example 4. The observation device 23, which was used to observe the observation light for confirming the intensity distribution of the laser beam at the spot, was used as the observation point during the optical simulation.

[0078] A laser beam with a wavelength of 1070 nm was then set to enter the connector portion 31 from the optical fiber 30, and a simulation was performed using the optical simulator Zemax OpticStudio (manufactured by Zemax, LLC). Figures 24-31 show the simulation results of the energy intensity distribution at the spot when the collimating lens 21a was shifted by 0.0 mm, 0.125 mm, 1.0 mm, and 4.0 mm. Figures 24-27 show the energy distribution in the image shape of the laser beam formed on the imaging surface of the observation device 23. The negative side of the Y position on the vertical axis corresponds to the forward region during laser processing, and the positive side corresponds to the backward region. The X position on the horizontal axis represents a coordinate perpendicular to the vertical axis. The relative ratio of the energy intensity at this time is indicated by the shade of color. Figures 28-31 also show the energy intensity distribution in the Y position direction when the X position in Figures 24-27 is zero. The horizontal axis represents the Y position, and the vertical axis represents the energy intensity of the laser beam.

[0079] 24 to 27, shifting the collimating lens 21a by 0.0 mm, 0.125 mm, 1.0 mm, and 4.0 mm confirmed that the energy intensity distribution changed from uniform to non-uniform while maintaining the annular image shape, as confirmed by the change in color intensity. Furthermore, as shown in Figures 28 to 31, the energy intensity ratio between the front and rear regions, when the energy intensity in the rear region is set to 1.0, is 1.0 with a 0.0 mm shift, but is 0.88 with a 0.125 mm shift, 0.49 with a 1.0 mm shift, and 0.12 with a 4.0 mm shift. [Example]

[0080] The laser beam irradiation optical unit of Example 5 had the same configuration as Example 4, except that the optical system of the second embodiment of the energy intensity distribution adjustment mechanism shown in Figure 4(b) was selected and the collimator lens 21b was the same lens as the collimator lens 21a of Example 4.

[0081] A laser beam with a wavelength of 1070 nm was then set to enter the connector portion 31 from the optical fiber 30, and a simulation was performed using the optical simulator Zemax OpticStudio (manufactured by Zemax, LLC). Figures 32-37 show the simulation results of the energy intensity distribution at the spot when the tilt angle of the collimating lens 21b was 0°, 1°, and 4°. Figures 32-34 show the energy distribution in the image shape of the laser beam formed on the imaging surface of the observation device 23, with the negative side of the Y position on the vertical axis corresponding to the forward region during laser processing and the positive side corresponding to the backward region. The X position on the horizontal axis represents the coordinate perpendicular to the vertical axis. The relative ratio of the energy intensity at this time is indicated by the shade of color. Figures 35-37 also show the energy intensity distribution in the Y position direction when the X position in Figures 32-34 is zero, with the horizontal axis representing the Y position and the vertical axis representing the energy intensity of the laser beam.

[0082] 32 to 34, it was confirmed by the change in color intensity that the energy intensity distribution changes from uniform to non-uniform while maintaining the annular image shape by setting the tilt angle of collimator lens 21b to 0°, 1°, and 4°. Furthermore, from Figures 35 to 37, it was confirmed that the energy intensity ratio between the front and rear regions, when the energy intensity in the rear region is set to 1.0, is 1.0 at a tilt of 0°, 0.86 at a tilt of 1°, and 0.34 at a tilt of 4°. [Example]

[0083] For the laser beam irradiation optical unit of Example 6, an optical system according to the third embodiment of the energy intensity distribution adjustment mechanism shown in Fig. 5(a) was selected. Here, an aspherical lens with a focal length of 200 mm and equipped with a circular conversion function was used as the collimating lens 21, and a lens with a focal length of 200 mm was used as the condenser lens 22. Then, from the laser oscillator side, the laser beam direction adjustment mechanism 20a, the collimating lens 21, the condenser lens 22, and an observation device 23 were arranged along the optical axis of the optical system of Example 6. The observation device 23, which was used to observe the observation light for confirming the intensity distribution of the laser beam at the spot, was used as the observation point during the optical simulation.

[0084] A laser beam with a wavelength of 1070 nm was then set to enter the connector portion 31 from the optical fiber 30, and a simulation was performed using the optical simulator Zemax OpticStudio (manufactured by Zemax, LLC). Figures 38-43 show the simulation results of the energy intensity distribution at the spot when the laser beam direction adjustment mechanism 20a was shifted by 0.0 mm, 0.125 mm, and 4.0 mm. Figures 38-40 show the energy distribution in the image shape of the laser beam formed on the imaging plane of the observation device 23. The negative side of the Y position on the vertical axis corresponds to the forward region during laser processing, and the positive side corresponds to the backward region. The X position on the horizontal axis represents a coordinate perpendicular to the vertical axis. The relative ratio of the energy intensity at this time is indicated by the shade of color. Figures 41-43 also show the energy intensity distribution in the Y position direction when the X position in Figures 38-40 is zero. The horizontal axis represents the Y position, and the vertical axis represents the energy intensity of the laser beam.

[0085] 38-40, by shifting the laser beam direction adjustment mechanism 20a by 0.0 mm, 0.125 mm, and 4.0 mm, the image shape remained annular, while the energy intensity distribution changed from uniform to non-uniform, as confirmed by the change in color intensity. Furthermore, as shown in Figures 41-43, when the energy intensity in the forward region is set to 1.0, the energy intensity in the forward region is 1.0 when shifted by 0.0 mm, 0.89 when shifted by 0.125 mm, and 0.14 when shifted by 4.0 mm. [Example]

[0086] The optical system of the third embodiment of the energy intensity distribution adjusting mechanism shown in Fig. 5(b) was selected as the laser beam irradiation optical unit of Example 7. Here, the configuration was the same as that of Example 6 except that the laser beam direction adjusting mechanism 20b was used.

[0087] A laser beam with a wavelength of 1070 nm was then set to enter the connector portion 31 from the optical fiber 30, and a simulation was performed using the optical simulator Zemax OpticStudio (manufactured by Zemax, LLC). Figures 44-49 show the simulation results of the energy intensity distribution at the spot when the tilt angle due to the "arc-shaped rotation" function of the laser beam direction adjustment mechanism 20b was 0°, 3°, and 7°. Figures 44-46 show the energy distribution in the image shape of the laser beam formed on the imaging surface of the observation device 23. The negative side of the Y position on the vertical axis corresponds to the forward region during laser processing, and the positive side corresponds to the backward region. The X position on the horizontal axis represents the coordinate perpendicular to the vertical axis. The relative ratio of the energy intensity at this time is indicated by the shade of color. Figures 47-49 also show the energy intensity distribution in the Y position direction when the X position in Figures 44-46 is zero. The horizontal axis represents the Y position, and the vertical axis represents the energy intensity of the laser beam.

[0088] 44-46, by setting the tilt angle of the "arc rotation" function of the laser beam direction adjustment mechanism 20b to 0°, 3°, and 7°, it was confirmed by the change in color intensity that the energy intensity distribution changed from uniform to non-uniform while maintaining the annular shape of the image. Furthermore, from Figures 47-49, it was confirmed that the energy intensity ratio in the front and rear regions, when the energy intensity in the rear region was set to 1.0, was 1.0 at a tilt of 0°, 0.63 at a tilt of 3°, and 0.49 at a tilt of 7°. [Industrial Applicability]

[0089] The laser beam irradiating optical unit of the present invention can melt the workpiece in the area in front of the laser beam spot in the moving direction, even when the spot moves at a high speed, and appropriately remove the molten metal from the workpiece in the area behind the spot. This prevents molten material from remaining on the cut surface or hole of the workpiece. Furthermore, a laser processing device using the laser beam irradiating optical unit of the present invention has high laser processing throughput. In other words, the laser beam irradiating optical unit of the present invention is suitable for laser processing, which processes a workpiece by irradiating it with a laser beam. [Explanation of symbols]

[0090] 1. Laser beam irradiation optical unit 10 Optical axis of irradiation orbit 11 Laser beam emission direction 12 Reference optical axis determined by the structure of the output end of the optical fiber and the structure of the connector 15 Irradiation trajectory 20 Laser beam direction adjustment mechanism 20a Laser beam direction adjustment mechanism 20b Laser beam direction adjustment mechanism 21 Collimating lens 21a Collimating lens 21b Collimating lens 22 Condenser lens 22a Condenser lens 22b Condenser lens 23 Observation equipment 30 Optical Fiber 30a optical fiber 30b optical fiber 31 Connector part 31a Connector part 31b Connector part 32 Connector receiving part 32a Connector receptacle 32b Connector receiving part 33 Telescope tube 34 Observation tube 40 Turning Trajectory

Claims

1. A laser beam irradiation optical unit for laser processing by forming a spot on a processing object with a laser beam irradiated from a laser oscillator, an energy intensity distribution adjusting mechanism that adjusts the energy intensity distribution of the laser beam at the spot within an irradiation trajectory of the laser beam from the laser oscillator to the workpiece so that the energy intensity distribution of the laser beam at the spot is asymmetric with respect to the traveling direction of the spot on the workpiece; an observation device within the irradiation orbit for confirming the energy intensity distribution at the spot adjusted by the energy intensity distribution adjustment mechanism, 10. An optical unit for laser beam irradiation, wherein the observation light observed by the observation device is the observation light for observation different from the laser beam.

2. 2. The laser beam irradiation optical unit according to claim 1, wherein the energy intensity distribution asymmetric with respect to the direction of travel of the spot is an energy intensity distribution in which the energy intensity of the laser beam is weak in a front region, which is a region on the workpiece in the direction of travel of the spot, and the energy intensity of the laser beam is strong in a rear region different from the front region.

3. 3. An optical unit for laser beam irradiation according to claim 1 or claim 2, wherein the intensity ratio of the energy intensity distribution asymmetric in the direction of travel of the spot is such that, when the strong energy intensity in the energy intensity distribution is 1, the weak energy intensity is 0.1 or more and 0.95 or less.

4. 4. The laser beam irradiation optical unit according to claim 1, wherein the image shape of the laser beam on the spot is an annular shape having at least an annular peripheral region.

5. The energy intensity distribution adjusting mechanism includes: a laser beam direction adjusting mechanism for adjusting the incident direction of the laser beam onto the irradiation trajectory; a collimating lens for collimating the laser beam; and 5. The laser beam irradiation optical unit according to claim 1, further comprising at least one condenser lens for condensing the laser beam onto the spot.

6. 6. A laser processing device comprising a laser processing head that accommodates the laser beam irradiation optical unit according to claim 1.

Images