Laser beam measurement device and output data correction method

Abstract

To provide a laser beam measurement device capable of attenuating a laser beam using a beam splitter to a level that does not damage a device that acquires image data even when the energy intensity of the laser beam is high, and accurately measuring the image shape of a spot and the energy intensity distribution of the laser beam.SOLUTION: A laser beam measurement device includes: a plate-type first beam splitter; an observation device that reads an image of a spot formed by the transmitted or reflected light of a laser beam incident on the first beam splitter; and a calculation device that performs numerical computation to correct the output data from the observation device. The device is configured such that the first beam splitter is tilted at an angle α in a range from 30° to 60° with respect to a plane perpendicular to an optical axis with an X-axis as the rotational axis when arbitrary orthogonal coordinate axes whose original point on a plane perpendicular to an optical axis of an optical unit for laser beam irradiation is on the optical axis are defined as the X-axis and a Y-axis.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a laser beam measuring device for a laser beam irradiated from a laser beam irradiation optical unit for forming a spot on an object to be processed and irradiating the object with the laser beam for laser processing, and a method for correcting output data in the laser beam measuring device. [Background technology]

[0002] In recent years, laser beams have been widely used to process various products. A laser beam is focused on one point and irradiated onto a workpiece, causing the surface temperature of the workpiece to rise rapidly, melting or evaporating the irradiated surface. A laser processing device that uses this laser beam is a device that processes the workpiece in this way, such as cutting, drilling, and welding. Since the laser beam is focused on one point, it is possible to perform pinpoint precise and fine processing. In addition, by using a higher energy laser beam, it is possible to shorten the processing time and process hard workpieces that are difficult to process with a blade.

[0003] Here, the laser processing device is equipped with a laser beam irradiation optical unit. Conventionally, the laser beam irradiation optical unit has a function of concentrating the laser beam on one spot or irradiating the laser beam so that the image shape of the laser beam on the spot is circular and the energy intensity distribution is Gaussian or top hat. However, in the laser processing using the conventional spot image shape, when cutting, welding, or drilling the workpiece, the workpiece melted by the laser beam remains on the cut surface or hole, which deteriorates the processing quality. Therefore, in recent years, a laser processing has been proposed in which the image shape of the laser beam on the spot is made annular, thereby appropriately scattering the melted workpiece and preventing it from remaining on the cut surface or hole.

[0004] In this way, the image shape of the laser beam at the spot and the energy intensity distribution in the image shape have changed from a circular Gaussian shape to an annular image shape or the like depending on the processing conditions such as welding and cutting of the workpiece. At this time, a laser beam measurement device is used to confirm that the image shape of the laser beam at the spot and the energy intensity distribution in the image shape are as desired before laser processing. As a means for attenuating the laser beam in this laser beam measurement device, a method of attenuating the laser beam with a filter and observing it with an image sensor such as a CCD or CMOS, a method of measuring the transmitted light intensity while blocking a part of the laser beam with a pinhole, a slit, or a knife edge, and calculating the intensity distribution from the correlation between the blocking position and the transmitted light intensity, a method of measuring the intensity distribution by scanning a rod with a small mirror at the tip or a light guiding rod with a small hole at the tip in the laser beam, a method of irradiating a laser beam on a plate that scatters the laser beam and taking an image of the scattered light from behind with a camera, and the like are known.

[0005] However, the above-mentioned method has problems such as the filter being deformed by the heat of the laser beam, the image shape of the laser beam being damaged in a pinhole, slit, or knife edge, it being difficult to measure a minute image shape in a small mirror, and the image being blurred when scattered light is used. Therefore, Patent Document 1 discloses a method in which a laser beam is irradiated onto a fluorescent screen, and the intensity distribution of the fluorescence emitted from the screen is measured using a camera or image sensor.

[0006] A method of irradiating a fluorescent screen with a laser beam and measuring the intensity distribution of the fluorescence emitted from it using a camera or image sensor is as follows. The fluorescent screen absorbs photons of the incident laser beam, electronically exciting the molecules of the fluorescent screen, and when the excited molecules return to the ground state, they emit photons of lower energy corresponding to a longer wavelength than the absorbed photon. These photons of longer wavelength are the fluorescence corresponding to the incident laser beam, and the energy of this fluorescence is lower than the energy of the incident laser beam. Here, since the wavelengths of the laser beam and the fluorescence are different, the laser beam and the fluorescence are separated using a light separation element (prism or mirror) that separates light of different wavelengths. The intensity distribution of this fluorescence is then measured to confirm the energy intensity distribution of the laser beam. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] International Publication No. 2019 / 021435 Summary of the Invention [Problem to be solved by the invention]

[0008] However, in the method using this fluorescent screen, if the thickness of the fluorescent screen is not thin, the image produced by the fluorescence will be blurred. Therefore, in the cited document 1, the thickness of the fluorescent screen is set to 0.2 mm. In this way, the method using the fluorescent screen requires a thin fluorescent screen, but this causes a problem that if the energy intensity of the incident laser beam is high, for example, 100 W or more, the fluorescent screen may be damaged by heat or the energy intensity of the fluorescence may become saturated, making it impossible to correctly measure the image shape and intensity distribution of the laser beam.

[0009] Therefore, a method is conceivable in which a laser beam is separated into transmitted light and reflected light using a beam splitter with a high energy intensity of the laser beam that can be incident thereon, and the transmitted light or reflected light with a lower energy intensity of the laser beam is used to measure the image shape and intensity distribution of the laser beam. For example, when a plate-type beam splitter is used, the surface of the beam splitter is arranged at a predetermined angle with respect to the optical axis. The laser beam incident on the beam splitter is not parallel light, but is focused light that is focused on a spot. In this case, the incidence angle of the laser beam at different incidence positions on the beam splitter is different. Here, generally, the transmittance or reflectance of the laser beam of the beam splitter is different depending on the incidence angle of the laser beam on the beam splitter. Therefore, since the transmittance or reflectance differs depending on the incidence position on the beam splitter, there is a problem that the energy intensity distribution cannot be measured correctly even if the measurement is performed using the transmitted light or reflected light of the beam splitter. In addition, when a focused light is incident on a beam splitter, the transmitted light from the beam splitter not only shifts its trajectory, but also generates astigmatism, which causes the light to be focused at a different focal length. In other words, the image of the transmitted light is distorted by astigmatism, which makes it impossible to measure the image shape of the laser beam spot correctly.

[0010] The present invention has been made in view of the above circumstances. It is an object of the present invention to provide a laser beam measurement device and an output data correction method that can accurately measure the image shape and energy intensity distribution of a laser beam spot by using a beam splitter to attenuate a laser beam to an extent that does not damage devices that acquire image data, such as image sensors and cameras, even if the energy intensity of the incident laser beam is high. [Means for solving the problem]

[0011] In order to solve the above-mentioned problems, the inventors have, as a result of extensive research, come up with the following laser beam measurement device and output data correction method.

[0012] The laser beam measurement device of the present invention is a laser beam measurement device for a laser beam irradiated from a laser beam irradiating optical unit for forming a spot on a workpiece and irradiating the laser beam to perform laser processing, and is equipped with a plate-type first beam splitter, an observation device for reading an image of the spot formed by transmitted light or reflected light of the laser beam incident on the first beam splitter, and a calculation device for performing numerical calculations on output data of the observation device to perform correction, and is characterized in that when the X-axis and Y-axis are arbitrary orthogonal coordinate axes whose origin in a plane perpendicular to the optical axis of the laser beam irradiating optical unit is the optical axis, the first beam splitter is positioned with the X-axis as the rotation axis and tilted at an angle α in the range of 30 degrees to 60 degrees with respect to the plane perpendicular to the optical axis.

[0013] It is preferable that the laser beam measurement device according to the present invention is the above-mentioned laser beam measurement device, further comprising a plate-type second beam splitter, and the second beam splitter is arranged at an angle -α with respect to a plane perpendicular to the optical axis, with an X'-axis that is parallel to the X-axis and passes through the optical axis as its axis of rotation, and the spot is formed by transmitted light of the laser beam incident on the first beam splitter and the second beam splitter.

[0014] The output data correction method according to the present invention is a method for correcting output data in a calculation device that performs numerical calculations to correct output data of an observation device that reads an image of a spot formed by the transmitted light of a laser beam incident on a first beam splitter in the above-mentioned laser beam measurement device, characterized in that a numerical calculation is performed to correct the energy intensity of the output data in the Y-axis direction of the output data based on the transmittance value of the first beam splitter corresponding to the incident angle of the laser beam on the first beam splitter, and a numerical calculation is performed to correct the coordinate position of the output data by correcting the coordinate position of the output data in the Y-axis direction based on the ratio value between the maximum image size in the X-axis direction of the image shape in the observation device and the maximum image size in the Y-axis direction.

[0015] The output data correction method of the present invention is a method for correcting output data in a calculation device that performs numerical calculations to correct output data from an observation device that reads an image of a spot formed by the reflected light of a laser beam incident on a first beam splitter in the above-mentioned laser beam measurement device, and employs an output data correction method characterized in that a numerical calculation is performed to correct the energy intensity in the output data in the Y-axis direction of the output data based on the reflectance value of the first beam splitter that corresponds to the incident angle of the laser beam on the first beam splitter.

[0016] The output data correction method according to the present invention is a method for correcting output data in a calculation device that performs numerical calculations and corrections on output data of an observation device that reads an image of a spot formed by transmitted light of a laser beam incident on a first beam splitter and a second beam splitter in a laser beam measurement device equipped with the above-mentioned second beam splitter, An output data correction method is adopted, which is characterized by performing a numerical calculation to correct the coordinate position in the output data by correcting the coordinate position in the Y-axis direction of the output data based on the ratio value between the maximum image size in the X-axis direction of the image shape in the observation device and the maximum image size in the Y-axis direction. Effect of the Invention

[0017] The laser beam measurement device of the present invention can measure the image shape and energy intensity distribution of the laser beam spot by attenuating the laser beam to a level that does not damage devices that acquire image data, such as image sensors and cameras, even if the energy intensity of the incident laser beam is high. The output data correction method of the present invention can correct the image shape of the output data to an appropriate image shape. The laser beam measurement device of the present invention can accurately measure the image shape and energy intensity distribution of the laser beam spot, even if the energy intensity of the laser beam is high. [Brief description of the drawings]

[0018] [Figure 1] 1 is a schematic diagram of a laser beam measurement device according to a first embodiment. [Diagram 2] 4 is an example of transmittance characteristics versus incident angle of a first beam splitter. [Diagram 3] FIG. 2 is an enlarged view of a first beam splitter portion. [Figure 4] 5 is a schematic diagram of a laser beam measurement device according to a second embodiment. [Diagram 5] 4 is an example of reflectance characteristics versus incident angle of a first beam splitter. [Figure 6] FIG. 2 is an enlarged view of a first beam splitter portion. [Figure 7] 13 is a schematic diagram of a laser beam measurement device according to a third embodiment. [Figure 8] FIG. 2 is an enlarged view of the first beam splitter and the second beam splitter. [Figure 9] 13 shows the results of measuring the energy intensity distribution of an image at a spot in Example 1. [Figure 10] 13 shows the image shape results for the spot in Example 1. [Figure 11] 13 shows the results of measuring the energy intensity distribution of an image at a spot in Example 2. [Figure 12] 13 shows the image shape results for the spot in Example 2. [Figure 13] 13 shows the results of measuring the energy intensity distribution of an image at a spot in Example 3. [Figure 14] 13 shows the image shape results for the spot in Example 3. [Figure 15] 13 shows the results of measuring the energy intensity distribution of an image in a spot in Comparative Example 1. [Figure 16] 13 shows the image shape results for the spots in Comparative Example 1. [Figure 17] 13 shows the results of measuring the energy intensity distribution of an image in a spot in Comparative Example 2. [Figure 18] 13 shows the image shape results for the spots in Comparative Example 2. [Figure 19]13 shows the results of measuring the energy intensity distribution of an image in a spot in Comparative Example 3. [Figure 20] 13 shows the image shape results for the spots in Comparative Example 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, the laser beam measurement device and the output data correction method according to the present invention will be described. Note that the following description merely shows one embodiment, and the present invention should not be construed as being limited to the following description.

[0020] 1. Laser beam measurement device The laser beam measurement device of the present invention attenuates a laser beam irradiated from a laser beam irradiation optical unit for forming a spot on an object to be processed and irradiating the laser beam to a level that does not damage a device for acquiring image data such as an image sensor or camera, and measures the image shape and energy intensity distribution of the laser beam spot.

[0021] The laser beam irradiating optical unit is an optical system necessary for laser processing, and is an optical system that irradiates a laser beam so as to form the image shape of the laser beam on the spot and the energy intensity distribution of the laser beam as desired, and to condense the laser beam on the spot. Here, the laser beam measuring device according to the present invention is attached between the laser beam irradiating optical unit and the spot, and is for measuring the image shape of the laser beam on the spot and the energy intensity distribution of the laser beam. After measuring the image shape of the laser beam on the spot and the energy intensity distribution of the laser beam, if necessary, the image shape of the laser beam on the spot and the energy intensity distribution of the laser beam are adjusted and measured again, and then the laser beam measuring device can be removed from the laser beam irradiating optical unit. Then, a workpiece is placed at the position of the spot, and laser processing can be performed. Also, the laser beam can be branched in the laser beam irradiating optical unit, and used as a laser beam measuring device for observing the image shape and energy intensity distribution of the laser beam during laser processing.

[0022] The laser beam irradiation optical unit according to the present invention may include any optical system as long as it can perform laser processing. For example, it may include a galvano optical system equipped with a galvano mirror.

[0023] 1 shows the layout configuration of the first embodiment 1 of the laser beam measurement device according to the present invention and a schematic irradiation trajectory of the laser beam. In the first embodiment 1 of the laser beam measurement device, an optical fiber 30 for guiding and emitting a laser beam output from a laser oscillator (not shown), a collimating lens 21 for converting the laser beam output in a divergent manner from the output end of the optical fiber 30 into a parallel beam, a condensing lens 22 for condensing the laser beam collimated by the collimating lens 21 into a spot on the surface of the workpiece, a light-reducing mechanism 40 for reducing the intensity of the laser beam condensed by the condensing lens 22, and an observation device 50 for observing an observation light for confirming the image shape and intensity distribution of the laser beam at the spot are arranged in this order from the laser oscillator side along the optical axis 10 of the irradiation trajectory of the laser beam irradiation optical unit 31. The positions of the optical center of the collimating lens 21 and the optical center of the condensing lens 22 are set to coincide with the optical axis 10 within the laser beam irradiation optical unit 31. With this configuration of the laser beam measurement device of the first embodiment 1, the laser beam converges and forms an image on a spot along the trajectory shown in the irradiation trajectory 15. The calculation device 51 is connected to the observation device 50 via a connection cable 52. The laser beam measurement device according to the present invention includes the above-mentioned light-reducing mechanism 40, the observation device 50, and the calculation device 51.

[0024] The laser beam incident from the laser oscillator to the laser beam irradiation optical unit 31 through the optical fiber 30 may be any laser beam that can be used for laser processing. In particular, it is preferable to use a near-infrared laser beam with an oscillation wavelength of about 920 to 1080 nm, such as 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, 940 to 1025 nm). Also, as long as it is a laser beam that can be used for laser processing, it may be a blue, green, or ultraviolet laser beam. In addition, the energy intensity distribution in a plane perpendicular to the optical axis 10 of the laser beam incident on the laser beam irradiation optical unit 31 may be Gaussian with strong energy in the center (optical axis portion) or may be uniform.

[0025] In FIG. 1, the collimating lens 21 and the condenser lens 22 are installed in the laser beam irradiation optical unit 31 so that their optical centers coincide with the optical axis 10. That is, the laser beam irradiation optical unit 31 is provided with an optical system required for laser processing. The laser beam irradiation optical unit 31 is connected to a dimming mechanism 40, and the dimming mechanism 40 is connected to an observation device 50. In this case, the dimming mechanism 40 may be covered with a lens barrel or the like so that the laser beam does not leak out of the dimming mechanism 40. The dimming mechanism 40 may also be detachable from the laser beam irradiation optical unit 31. By connecting the detachable dimming mechanism 40, which can be connected to the observation device 50, to the laser beam irradiation optical unit 31 that constitutes the optical axis 10 of the laser beam irradiation orbit 15, the image shape of the laser beam at the spot and the energy intensity distribution of the laser beam can be measured. Then, measurements are performed using the observation device 50 to adjust the image shape and intensity distribution of the laser beam at the spot to the desired ones, and then the dimming mechanism 40 and the observation device 50 are removed, and the surface of the object to be processed is positioned at the location where the imaging surface of the observation device 50 was located, thereby allowing laser processing to be performed with high precision.

[0026] Here, the image shape of the laser beam at the spot may be any image shape as long as the workpiece can be processed with the laser beam. For example, at least one of the collimator lens 21 and the condenser lens 22 of the laser beam irradiation optical unit 31 can have 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 area (hereinafter referred to as an annular conversion function in this specification). By making the shape of the energy intensity distribution of the spot into an annular shape consisting of at least an annular peripheral area, the energy of the laser beam is uniformly irradiated in all directions from the central area of ​​the spot on the surface of the workpiece. This allows zinc gas to escape during lap welding of molten zinc steel sheets, resulting in clean welding.

[0027] In addition, the shape of the spot by the annular transformation function is not particularly limited, and may be, for example, a ring shape and a dot shape (the dot part is Gaussian-shaped) in the center of the ring, or a top-hat shape. In this case, it is preferable that the energy intensity of the dot spot in the center of the ring is higher than the energy intensity of the ring. This is because, for example, in aluminum, which has a high light reflectance, the metal can be melted in the ring part with a weak energy intensity to reduce the reflectance, and the object to be processed can be deeply melted in the center with a high energy intensity, making laser processing easier.

[0028] In order to form the image shape of the spot described above, it is preferable that at least one of the optically effective surfaces of the optical element having an annular conversion function is a diffractive lens, an axicon lens, or an aspheric lens, because the spot shape of the laser beam can be annular or composed of an annular shape and a dot at the center of the annular shape.

[0029] In addition, the laser beam irradiation optical unit 31 does not necessarily have to have a circular conversion function, and a laser beam whose image shape emitted from the optical fiber 30 is a circular shape consisting of at least a circular peripheral area may be used.

[0030] The laser beam irradiation optical unit 31 may also include a laser beam direction adjustment mechanism consisting of a connector portion to which the optical fiber 30 is connected and a connector receiving portion that fixes the connector portion to the optical axis 10 of the irradiation orbit. The laser beam direction adjustment mechanism adjusts the incident direction of the laser beam to the irradiation orbit by rotating at least one of the connector portion and the connector receiving portion 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. The laser beam output from the laser oscillator is guided to the laser processing head of the laser processing device using the optical fiber 30, and the emission direction of the laser beam output from the output end of the optical fiber 30 has a certain range of inclination with respect to the optical axis 10. Specifically, for example, in the CW fiber laser of Raycus Fiber, the angle of the optical axis of the laser beam output from the output end of the optical fiber with respect 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 (milliradian) or less. The laser beam direction adjustment mechanism can be used when the emission direction of the laser beam output from the output end of the optical fiber 30 has a certain range of inclination with respect to the optical axis 10, to adjust the incidence direction of the laser beam onto the irradiation trajectory.

[0031] Although the optical unit 31 for laser beam irradiation is configured to include a collimator lens 21 and a condenser lens 22, any configuration may be used as long as it is possible to perform laser processing, and for example, it may include only the condenser lens 22.

[0032] [First embodiment of laser beam measurement device] As shown in Fig. 1, the first embodiment of the laser beam measurement device according to the present invention includes an attenuation mechanism 40 having a plate-type first beam splitter 41 on the spot side (observation device 50 side) of the laser beam irradiation optical unit 31, an observation device 50 that reads an image of a spot formed by transmitted light of a laser beam incident on the first beam splitter 41, and a calculation device 51 that performs numerical calculations on output data of the observation device 50 to perform correction. The observation device 50 and the calculation device 51 are connected via a connection cable 52. The laser beam measurement device according to the present invention includes the above-mentioned attenuation mechanism 40, the observation device 50, and the calculation device 51. The first beam splitter 41 may be disposed so that the center position of the first beam splitter 41 coincides with the optical axis 10, but may also be disposed so that at least the irradiation trajectory 15 of the laser beam is within the optically effective surface of the first beam splitter 41. When the X-axis and Y-axis are arbitrary orthogonal coordinate axes whose origin on a plane perpendicular to the optical axis 10 is the optical axis 10, the first beam splitter 41 is arranged tilted at an angle α in the range of 30 degrees to 60 degrees with respect to the plane perpendicular to the optical axis 10 with the X-axis as the rotation axis. Note that the plane perpendicular to the optical axis 10 in FIG. 1 is a plane perpendicular to the optical axis 10 that includes only one point on the optical axis 10, the X-axis is a straight line on the plane perpendicular to the optical axis 10 that perpendicularly passes through the plane when the figure in FIG. 1 is taken as a plane with the optical axis 10 as the origin, and the Y-axis is a straight line on the plane perpendicular to the optical axis 10 that is perpendicular to the X-axis on the plane when the figure in FIG. 1 is taken as a plane with the optical axis 10 as the origin. In the present invention, the X-axis and Y-axis are defined in the same manner as above in other figures as well.

[0033] The first beam splitter 41 has a function of splitting the incident laser beam into transmitted light and reflected light. In FIG. 1, the irradiation trajectory 15 of the laser beam shows the trajectory of the laser beam incident on the first beam splitter 41 and the trajectory of the transmitted light of the first beam splitter 41, and the reflected light of the first beam splitter 41 is omitted. That is, in the first embodiment, the observation device 50 observes the transmitted light of the first beam splitter 41. At this time, the transmittance of the laser beam of the first beam splitter 41 when the incident angle of the laser beam to the first beam splitter 41 based on the optical surface of the first beam splitter 41 is 45 degrees is preferably 0.1% or more and 5.0% or less. This is because the energy intensity of the transmitted light component of the laser beam decreases with respect to the incident laser beam. The unnecessary reflected light reflected by the first beam splitter 41 may be absorbed and dissipated by irradiating it on a copper plate or the like whose surface has been processed to be black so as to easily absorb the laser beam.

[0034] The thickness of the first beam splitter 41 is not particularly limited as long as it can be used in the light-reducing mechanism 40 .

[0035] Furthermore, in a plate-type beam splitter, refraction causes the transmitted light to shift relative to the optical axis 10 (the shift of the transmitted light is not shown in Figs. 1 and 3). However, since the light-reducing mechanism 40 is intended to measure the energy intensity distribution and image shape of the laser beam with the observation device 50, the shift of the transmitted light relative to the optical axis 10 does not pose a problem.

[0036] A beam splitter is usually designed to have a predetermined transmittance or reflectance when the incident angle of the laser beam on the beam splitter based on the optical surface of the beam splitter is 45 degrees. When the incident angle of the laser beam on the beam splitter changes continuously from 45 degrees to different values, the transmittance value of the beam splitter changes continuously to different values. FIG. 2 shows a design example of the transmittance against the incident angle of a beam splitter in which the incidence angle dependency of the transmittance is reduced by using a 19-layer optical thin film. The horizontal axis indicates the incident angle (°) of the laser beam on the beam splitter, and the vertical axis indicates the transmittance (%) of the laser beam. Here, the transmittance at an incident angle of 40° is 0.75%, and the transmittance at an incident angle of 50° is 0.92%. In FIG. 1, as shown by the irradiation trajectory 15, the laser beam is incident on the first beam splitter 41 via the condenser lens 22, so that the incident angle of the laser beam on the first beam splitter 41 changes continuously in the direction of the Y axis described above. 2, if the incident angle to the first beam splitter 41 is 40° at minimum and 50° at maximum, the transmittance ratio of the transmitted light at the minimum and maximum incident angles is 0.92 / 0.75=1.2 times. In this case, the energy intensity distribution of the laser beam at the spot cannot be measured correctly.

[0037] An enlarged view of the first beam splitter 41 is shown in FIG. 3. In FIG. 3, the irradiation trajectory 15 of the laser beam shows the trajectory of the laser beam incident on the first beam splitter 41 and the trajectory of the light transmitted through the first beam splitter 41, and the reflected light of the first beam splitter 41 is omitted. Here, the first beam splitter 41 is arranged tilted at an angle α with respect to the plane 61 perpendicular to the optical axis 10 in the above-mentioned range, with the X-axis as the rotation axis. The value of the incidence angle of the laser beam at the position of the optical axis 10 on the first beam splitter 41 with reference to the optical surface of the first beam splitter 41 is (90-α) when expressed as an angle smaller than 90 degrees, as shown in FIG. 3. For example, the incidence angle of the laser beam at the position of the upper end of the irradiation trajectory 15 on the first beam splitter 41 with reference to the optical surface of the first beam splitter 41 is expressed as (90-α)-θ with reference to the value of the incidence angle at the position of the optical axis 10. Moreover, the incidence angle of the laser beam at the position of the lower end of the irradiation trajectory 15 on the first beam splitter 41 with reference to the optical surface of the first beam splitter 41 is expressed as (90-α)+θ when the value of the incidence angle at the position of the optical axis 10 is used as a reference. Here, the angle θ is the incidence angle of the laser beam at the position of the upper end or lower end of the irradiation trajectory 15 with respect to a virtual line 62 parallel to the optical axis 10, that is, the angle of difference from the incidence angle at the position of the optical axis 10. In other words, the value of the incidence angle of the laser beam at the first beam splitter 41 with reference to the optical surface of the first beam splitter 41 changes continuously within the range from (90-α)-θ to (90-α)+θ.

[0038] As described above, since the value of the incident angle of the laser beam to the first beam splitter 41 with respect to the optical surface of the first beam splitter 41 changes continuously, the value of the transmittance of the first beam splitter 41 changes continuously depending on the incident position. Therefore, the energy intensity distribution of the transmitted light of the laser beam that has passed through the first beam splitter 41 changes in the Y-axis direction in accordance with the change in transmittance, relative to the energy intensity distribution of the incident light. In other words, the energy intensity distribution of the laser beam measured by the observation device 50 is a distribution biased in the Y-axis direction relative to the energy intensity distribution of the laser beam incident on the light-attenuating mechanism 40.

[0039] The energy intensity distribution of the output data of the laser beam measured in a biased manner in the Y-axis direction can be corrected by performing a numerical calculation using the arithmetic device 51. A method of correcting the output data to an energy intensity distribution similar to that of the laser beam incident on the first beam splitter 41 by performing a numerical calculation to correct the energy intensity distribution of the output data in the Y-axis direction will be described below, but the following description is not intended to be limited to the above description as long as the energy intensity distribution position of the output data can be corrected in the Y-axis direction. First, incident angle dependency data of the transmittance of the first beam splitter 41 is acquired in advance. Furthermore, for example, at each data position on the imaging surface of the observation device 50 at the spot position, the incident angle data of the first beam splitter 41 is acquired in advance by tracing the optical path of the light beam toward the emission point of the laser beam from the optical fiber 30 using a ray tracing method. These previously acquired data are stored in the storage device of the arithmetic device 51. Then, based on the incident angle data of the first beam splitter 41 at each data position on the imaging surface of the observation device 50 acquired in advance, the incident angle of the first beam splitter 41 is determined from the data position on the imaging surface of the observation device 50 for the output data of the observation device 50 resulting from the incidence of the laser beam. Furthermore, based on the incident angle dependency data of the transmittance of the first beam splitter 41 acquired in advance, the energy intensity values ​​of the output data of the observation device 50 are corrected for other positions using the transmittance of the incident angle to the first beam splitter 41 at the position of the optical axis 10 as a reference.

[0040] More specifically, for example, the following can be performed. The coordinate value of the X-axis of the output data at an arbitrary position from the observation device 50 is x, and the coordinate value of the Y-axis is y. Then, if the transmittance of the incident angle to the first beam splitter 41 at the position of the optical axis 10 is a, the transmittance of the incident angle to the first beam splitter 41 of the laser beam that reaches an arbitrary coordinate position (x, y) on the imaging surface of the observation device 50 is b, and the energy intensity value in the output data at the arbitrary coordinate position (x, y) of the observation device 50 is E, the corrected energy intensity value E' at the arbitrary coordinate position (x, y) of the observation device 50 can be corrected as E' = (a / b) · E. That is, for the Y-axis direction of the output data, the energy intensity in the output data can be corrected based on the transmittance value of the first beam splitter 41 corresponding to the incident angle of the laser beam to the first beam splitter 41. In this way, the energy intensity distribution of the laser beam, which is a distribution biased in the Y-axis direction and measured by the observation device 50, can be corrected to an energy intensity distribution similar to the energy intensity distribution of the laser beam incident on the first beam splitter 41 by using the arithmetic device 51. Therefore, it is preferable that the arithmetic device 51 has a numerical calculation function capable of performing the above-mentioned calculations.

[0041] Since the first beam splitter 41 is disposed tilted at an angle α with the X-axis as the rotation axis, the incident angle of the laser beam on the optical surface of the first beam splitter 41 does not change in the direction of the X-axis. Therefore, the energy intensity distribution of the laser beam measured by the observation device 50 is not biased in the direction of the X-axis with respect to the energy intensity distribution of the laser beam incident on the attenuation mechanism 40.

[0042] Next, as shown in FIG. 3, the first beam splitter 41 is disposed with the X-axis as the rotation axis and tilted at an angle α in the range of 30 degrees to 60 degrees with respect to the plane perpendicular to the optical axis 10. When a plate-type beam splitter is disposed with the X-axis as the rotation axis and parallel light is incident on the beam splitter, the trajectory of the light emitted from the beam splitter shifts with respect to the incident light due to refraction. When focused light is incident on the beam splitter, in addition to the shift in trajectory, astigmatism occurs in which the emitted light is focused at the same focal length in the X-axis direction but at a different focal length in the Y-axis direction. That is, the image of the laser beam transmitted through the first beam splitter 41 with the X-axis as the rotation axis is distorted in the Y-axis direction due to astigmatism.

[0043] The image shape of the output data of the laser beam that is measured distorted in the Y-axis direction can be corrected by performing a numerical calculation using the calculation device 51. Below, a method of correcting the output data to a similar image shape to the image shape of the laser beam incident on the first beam splitter 41 by performing a numerical calculation to correct the image shape of the output data in the Y-axis direction will be described, but as long as the image shape of the output data can be corrected in the Y-axis direction, the following description should not be construed as being limited to the above.

[0044] The first method is a method of correcting output data that can be used when the outer circumferential contour of the image shape on a plane perpendicular to the optical axis 10 of the laser beam incident on the dimming mechanism 40 is a circle. In this case, since the outer circumferential contour of the image shape on a plane perpendicular to the optical axis 10 of the laser beam incident on the dimming mechanism 40 is a circle, the ratio of the size in the X-axis direction to the size in the Y-axis direction of the outer circumferential contour of the image shape of the laser beam incident on the dimming mechanism 40 is 1:1. In this case, since the image on the X-axis of the image shape in the spot of the laser beam output from the dimming mechanism 40 is not distorted, the Y-axis position of the output data can be corrected using the ratio of the diameter of the image on the Y-axis to the diameter of the image on the X-axis as a reference.

[0045] For example, on the imaging surface of the observation device 50, the diameter value of the image in the X-axis direction is c, the diameter value of the image in the Y-axis direction is d, the X-axis coordinate value of the output data of an arbitrary position from the observation device 50 is x, and the Y-axis coordinate value is y. In this case, the data position after correction of the arbitrary position can be expressed as the X-axis coordinate value x and the Y-axis coordinate value (c / d)·y. That is, by performing a numerical calculation to correct the coordinate position of the output data from the observation device 50 in the Y-axis direction as described above using the calculation device 51, corrected output data having an image shape similar to the image shape of the laser beam incident on the first beam splitter 41 can be obtained. By displaying this corrected output data on a display device, it can be observed as the image shape at the spot. Therefore, it is preferable that the calculation device 51 has a numerical calculation function capable of performing the above-mentioned calculation.

[0046] The second method is an output data correction method that can be used when the outer contour of the image shape of the laser beam incident on the dimming mechanism 40 on a plane perpendicular to the optical axis 10 is a circle or a shape other than a circle. First, optical calculation is performed based on optical information of the optical system on the light source side of the dimming mechanism 40, i.e., the image shape of the laser beam from the light source and optical information of the collimator lens 21 and the condenser lens 22, to obtain image shape data (primary data) of the laser beam at multiple spot positions (focal length positions) without including the dimming mechanism 40 in advance, and store the data in the storage device of the calculation device 51. Next, in the optical system including the dimming mechanism 40, a laser beam is irradiated, and image shape data (secondary data) of the laser beam is obtained from the observation device 50 at an arbitrary position set as the spot position.

[0047] Then, from the primary data, image shape data at the same spot position (focal length position) as that at which the secondary data was acquired is selected, and the value of the maximum image size in the X-axis direction of the image shape is e, and the value of the maximum image size in the Y-axis direction is f. Also, from the secondary data, the value of the maximum image size in the X-axis direction of the image shape is g, and the value of the maximum image size in the Y-axis direction is h. In this case, if the X-axis coordinate value of an arbitrary position of the output data from the observation device 50 is x, and the Y-axis coordinate value is y, the data position after correction of the arbitrary position can be expressed as the X-axis coordinate value x and the Y-axis coordinate value ((f·g) / (e·h))·y. That is, by using the calculation device 51 to perform a numerical calculation for correcting the coordinate position in the Y-axis direction as described above for the output data from the observation device 50, the corrected output data can be obtained as an image shape similar to the image shape of the laser beam incident on the first beam splitter 41. By displaying this corrected output data on a display device, it can be observed as an image shape at the spot. Therefore, it is preferable that the arithmetic unit 51 has a numerical calculation function capable of performing the above-mentioned calculations.

[0048] In the above, when the diameter value of the image on the X-axis or Y-axis or the value of the maximum image size in the X-axis or Y-axis direction cannot be clearly determined, the diameter value of the image on the X-axis or Y-axis or the value of the maximum image size in the X-axis or Y-axis direction may be determined from the contour data of an image having a predetermined intensity (e.g., 10%) when the maximum value of the energy intensity of the laser beam measured by the observation device 50 is set to 100%.

[0049] That is, for the Y-axis direction of the output data, the coordinate position in the output data can be corrected by correcting the Y-axis direction coordinate position of the output data based on the ratio value between the maximum value of the image size in the X-axis direction of the image shape in the observation device 50 and the maximum value of the image size in the Y-axis direction. By using the above-mentioned first method, second method, etc., the image shape of the laser beam spot distorted in the Y-axis direction measured by the observation device 50 can be corrected to a correct image shape (an image shape similar to the image shape of the laser beam incident on the dimming mechanism 40) by using the calculation device 51.

[0050] In view of the above, in the first embodiment of the laser beam measurement device, it is preferable to provide a calculation device 51 having a numerical calculation function for correcting the energy intensity of the output data from the observation device 50 in the Y-axis direction and for correcting the coordinate position of the output data in the Y-axis direction.

[0051] In addition, in the configuration of the dimming mechanism 40 shown in Figure 1, if the energy intensity of the laser beam is insufficient to be dimmed so that it can be incident on the observation device 50, an optical element such as an ND filter capable of dimming the laser beam may be placed between the first beam splitter 41 and the observation device 50.

[0052] As described above, the first embodiment of the laser beam measurement device according to the present invention includes the attenuation mechanism 40 having the first beam splitter 41 on the spot side of the laser beam irradiation optical unit 31, the observation device 50 that measures information on the image of the laser beam focused at the spot position, and the calculation device 51 that performs numerical calculations on output data of the observation device 50 to perform correction, and when any orthogonal coordinate axes with the origin on the optical axis 10 on a plane perpendicular to the optical axis 10 are defined as the X-axis and the Y-axis, the first beam splitter 41 is disposed tilted at an angle α in the range of 30 degrees to 60 degrees with respect to the plane perpendicular to the optical axis 10, with the X-axis as the rotation axis. As a result, the power of the laser beam that can be incident is normally large at 1 kW, and the energy intensity of the laser beam can be reduced to a level that does not destroy the observation device 50 that acquires image data, such as an image sensor or a camera, and output from the attenuation mechanism 40. Then, for the Y-axis direction of the output data from the observation device 50, the energy intensity of the output data can be corrected for the Y-axis direction by using the calculation device 51 having a numerical calculation function, and the coordinate position of the output data can be corrected for the Y-axis direction. By using the output data after this correction, it is possible to measure the energy intensity distribution at the spot, which is similar to the energy intensity distribution of the laser beam incident on the light-attenuating mechanism 40 and has an image shape similar to the image shape of the laser beam incident on the light-attenuating mechanism 40.

[0053] [Second embodiment of laser beam measurement device] As shown in FIG. 4, the second embodiment of the laser beam measurement device according to the present invention includes an attenuation mechanism 40 having a plate-type first beam splitter 42 on the spot side (observation device 50 side) of the laser beam irradiation optical unit 31, an observation device 50 that reads an image of the spot formed by the reflected light of the laser beam incident on the first beam splitter 42, and a calculation device 51 that performs numerical calculations on output data of the observation device 50 to perform correction. The observation device 50 and the calculation device 51 are connected via a connection cable 52. The laser beam measurement device according to the present invention includes the above-mentioned attenuation mechanism 40, the observation device 50, and the calculation device 51. The first beam splitter 42 may be disposed so that the center position of the first beam splitter 42 coincides with the optical axis 10, but may also be disposed so that at least the irradiation trajectory 15 of the laser beam is within the optically effective surface of the first beam splitter 42. When the X-axis and Y-axis are arbitrary orthogonal coordinate axes whose origin on a plane perpendicular to the optical axis 10 is the optical axis 10, the first beam splitter 42 is arranged tilted at an angle α in the range of 30 degrees to 60 degrees with respect to the plane perpendicular to the optical axis 10 with the X-axis as the rotation axis. Note that the plane perpendicular to the optical axis 10 in FIG. 4 is a plane perpendicular to the optical axis 10 that includes only one point on the optical axis 10, the X-axis is a straight line on the plane perpendicular to the optical axis 10 that perpendicularly passes through the plane when the optical axis 10 is taken as the origin and the figure of FIG. 4 is taken as a plane, and the Y-axis is a straight line on the plane perpendicular to the optical axis 10 that is perpendicular to the X-axis on the plane when the optical axis 10 is taken as the origin and the figure of FIG. 4 is taken as a plane. In the present invention, the X-axis and the Y-axis are defined in the same manner as above in other figures as well.

[0054] The first beam splitter 42 has a function of splitting the incident laser beam into transmitted light and reflected light. In FIG. 4, the irradiation trajectory 15 of the laser beam shows the trajectory of the laser beam incident on the first beam splitter 42 and the trajectory of the reflected light of the first beam splitter 42, and the transmitted light of the first beam splitter 42 is not shown. That is, in the second embodiment, the observation device 50 observes the reflected light of the first beam splitter 42. At this time, the reflectance of the laser beam of the first beam splitter 42 at an incidence angle of the laser beam to the first beam splitter 42 based on the optical surface of the first beam splitter 42 is preferably 0.1% or more and 5.0% or less. This is because the energy intensity of the reflected light component of the laser beam decreases with respect to the incident laser beam. The unnecessary transmitted light that has passed through the first beam splitter 42 may be absorbed and dissipated by irradiating it on a copper plate or the like whose surface has been blackened to easily absorb the laser beam.

[0055] The thickness of the first beam splitter 42 is not particularly limited as long as it can be used in the light-reducing mechanism.

[0056] A beam splitter is usually designed to have a predetermined transmittance or reflectance when the incidence angle of the laser beam on the beam splitter based on the optical surface of the beam splitter is 45 degrees. When the incidence angle of the laser beam on the beam splitter changes continuously from 45 degrees to different values, the reflectance value of the beam splitter changes continuously to different values. In FIG. 4, as shown by the irradiation trajectory 15, the laser beam is incident on the first beam splitter 42 via the condenser lens 22, so that the incidence angle of the laser beam on the first beam splitter 42 changes continuously in the direction of the Y axis described above. FIG. 5 shows a design example of the reflectance against the incidence angle of a beam splitter in which a thin film is not formed on the surface of the plate and the incidence angle dependency is relatively large. The horizontal axis indicates the incidence angle (°) of the laser beam on the beam splitter, and the vertical axis indicates the reflectance (%) of the laser beam. Here, the reflectance at an incidence angle of 40 degrees is 3.95%, and the reflectance at an incidence angle of 50 degrees is 5.00%. 5, if the incident angle to the first beam splitter 42 is 40° at minimum and 50° at maximum, the reflectance ratio of the reflected light at the minimum and maximum incident angles is 5.00 / 3.95=1.27. In this case, the energy intensity distribution of the laser beam at the spot cannot be measured correctly.

[0057] This will be explained with reference to FIG. 6, which is an enlarged view of the first beam splitter 42. The first beam splitter 42 is disposed tilted at an angle α with respect to the plane 63 perpendicular to the optical axis 10 in the above-mentioned range with the X-axis as the rotation axis. The value of the incidence angle of the laser beam at the position of the optical axis 10 to the first beam splitter 42 with reference to the optical surface of the first beam splitter 42 is (90-α) when expressed as an angle smaller than 90 degrees, as shown in FIG. 6. For example, the incidence angle of the laser beam at the position of the upper end of the irradiation orbit 15 to the first beam splitter 42 with reference to the optical surface of the first beam splitter 42 is expressed as (90-α)-θ when the value of the incidence angle at the position of the optical axis 10 is used as the reference. Moreover, the incidence angle of the laser beam at the position of the lower end of the irradiation orbit 15 to the first beam splitter 42 with reference to the optical surface of the first beam splitter 42 is expressed as (90-α)+θ when the value of the incidence angle at the position of the optical axis 10 is used as the reference. Here, the angle θ is the incidence angle of the laser beam at the position of the upper end or lower end of the irradiation trajectory 15 with respect to the imaginary line 64 parallel to the optical axis 10, that is, the angle difference from the incidence angle at the position of the optical axis 10. In other words, the value of the incidence angle of the laser beam to the first beam splitter 42 with reference to the optical surface of the first beam splitter 42 changes continuously within the range from (90-α)-θ to (90-α)+θ.

[0058] As described above, since the value of the incident angle of the laser beam to the first beam splitter 42 with respect to the optical surface of the first beam splitter 42 changes continuously, the value of the reflectance of the first beam splitter 42 changes continuously depending on the incident position. Therefore, the energy intensity distribution of the reflected light of the laser beam reflected by the first beam splitter 42 changes in the Y-axis direction in response to the change in reflectance, relative to the energy intensity distribution of the incident light. In other words, the energy intensity distribution of the laser beam measured by the observation device 50 is a distribution biased in the Y-axis direction relative to the energy intensity distribution of the laser beam incident on the light-attenuating mechanism 40.

[0059] The energy intensity distribution of the output data of the laser beam measured in a biased manner in the Y-axis direction can be corrected by performing a numerical calculation using the above-mentioned arithmetic device 51. A method of correcting the output data to an energy intensity distribution similar to that of the laser beam incident on the first beam splitter 42 by performing a numerical calculation to correct the energy intensity distribution of the output data in the Y-axis direction will be described below, but the following description is not intended to be limited to the above description as long as the energy intensity distribution position of the output data can be corrected in the Y-axis direction. First, incident angle dependency data of the reflectance of the first beam splitter 42 is acquired in advance. Furthermore, for example, at each data position on the imaging surface of the observation device 50 at the spot position, incident angle data of the first beam splitter 42 is acquired in advance by tracing the optical path of the light beam toward the emission point of the laser beam from the optical fiber 30 using a ray tracing method. These previously acquired data are stored in the storage device of the arithmetic device 51. Then, based on the incident angle data of the first beam splitter 42 at each data position on the imaging surface of the observation device 50 acquired in advance, the incident angle of the first beam splitter 42 is determined from the data position on the imaging surface of the observation device 50 for the output data of the observation device 50 resulting from the incidence of the laser beam. Furthermore, based on the incident angle dependency data of the reflectance of the first beam splitter 42 acquired in advance, the energy intensity values ​​of the output data of the observation device 50 are corrected for other positions using the reflectance of the incident angle to the first beam splitter 42 at the position of the optical axis 10 as a reference.

[0060] More specifically, for example, the following can be performed. The coordinate value of the X-axis of the output data at an arbitrary position from the observation device 50 is x, and the coordinate value of the Y-axis is y. Then, if the reflectance of the incident angle to the first beam splitter 42 at the position of the optical axis 10 is i, the reflectance of the incident angle to the first beam splitter 42 of the laser beam that reaches an arbitrary coordinate position (x, y) on the imaging surface of the observation device 50 is j, and the energy intensity value in the output data at the arbitrary coordinate position (x, y) of the observation device 50 is E, the corrected energy intensity value E' at the arbitrary coordinate position (x, y) of the observation device 50 can be corrected as E' = (i / j) · E. That is, for the Y-axis direction of the output data, the energy intensity in the output data can be corrected based on the reflectance value of the first beam splitter 42 corresponding to the incident angle of the laser beam to the first beam splitter 42. In this way, the energy intensity distribution of the laser beam, which is a distribution biased in the Y-axis direction and measured by the observation device 50, can be corrected to an energy intensity distribution similar to the energy intensity distribution of the laser beam incident on the first beam splitter 42, using the arithmetic device 51. Therefore, it is preferable that the arithmetic device 51 has a numerical calculation function capable of performing the above-mentioned calculations.

[0061] Since the first beam splitter 42 is disposed tilted at an angle α with the X-axis as the axis of rotation, the incident angle of the laser beam on the optical surface of the first beam splitter 42 does not change in the direction of the X-axis. Therefore, the energy intensity distribution of the laser beam measured by the observation device 50 is not biased in the direction of the X-axis with respect to the energy intensity distribution of the laser beam incident on the attenuation mechanism 40.

[0062] In view of the above, the second embodiment of the laser beam measurement device preferably includes a calculation device 51 having a numerical calculation function for correcting the energy intensity of the output data from the observation device 50 in the Y-axis direction.

[0063] In the first embodiment of the laser beam measurement device, the image of the laser beam transmitted through the first beam splitter 41 is distorted in the Y-axis direction due to astigmatism when measured. On the other hand, the light attenuation mechanism 40 of the second embodiment 2 of the laser beam measurement device in the second embodiment of the laser beam measurement device uses the reflected light of the first beam splitter 42. That is, the light emitted from the first beam splitter 42 converges at the same focal length, and no astigmatism occurs. Therefore, in the second embodiment of the laser beam measurement device, no distortion in the Y-axis direction occurs in the image shape of the output data of the laser beam, and correction of the output data of the laser beam for distortion in the Y-axis direction is not necessarily required.

[0064] Furthermore, in the configuration of the dimming mechanism 40 shown in Figure 4, if the energy intensity of the laser beam is insufficient to be dimmed for it to be incident on the observation device 50, an optical element such as an ND filter capable of dimming the laser beam may be placed between the first beam splitter 42 and the observation device 50.

[0065] As described above, the second embodiment of the laser beam measurement device according to the present invention includes the attenuation mechanism 40 having the first beam splitter 42 on the spot side of the laser beam irradiation optical unit 31, the observation device 50 for measuring information on the image of the laser beam formed at the spot position, and the arithmetic device 51 for performing numerical calculation and correction of the output data of the observation device 50. When the X-axis and the Y-axis are arbitrary orthogonal coordinate axes whose origin on a plane perpendicular to the optical axis 10 is the optical axis 10, the first beam splitter 42 is arranged tilted at an angle α in the range of 30 degrees to 60 degrees with respect to the plane perpendicular to the optical axis 10, with the X-axis as the rotation axis. As a result, even if the power of the laser beam that can be incident is as high as 1 kW even in normal cases, the energy intensity of the laser beam can be reduced to a level that does not destroy the observation device 50 that acquires image data, such as an image sensor or a camera, and output from the attenuation mechanism 40. Then, the energy intensity of the output data from the observation device 50 can be corrected in the Y-axis direction by using the arithmetic device 51 having a numerical calculation function. By using this corrected output data, it is possible to measure an energy intensity distribution at the spot that is similar to the energy intensity distribution of the laser beam incident on the dimming mechanism 40 and has an image shape that is similar to the image shape of the laser beam incident on the dimming mechanism 40.

[0066] [Third embodiment of laser beam measurement device] As shown in FIG. 7, the third embodiment of the laser beam measurement device according to the present invention is configured by adding a second beam splitter 43 to the light attenuation mechanism 40 of the first embodiment of the laser beam measurement device shown in FIG. 1. That is, the observation device 50 is configured to read an image of a spot formed by the transmitted light of the laser beam incident on the first beam splitter 41 and the second beam splitter 43. The second beam splitter 43 may be disposed so that the center position of the second beam splitter 43 coincides with the optical axis 10, but may also be disposed so that at least the irradiation trajectory 15 of the laser beam is within the optically effective surface of the second beam splitter 43. When the X-axis and the Y-axis are arbitrary orthogonal coordinate axes whose origin on a plane perpendicular to the optical axis 10 is the optical axis 10, the second beam splitter 43 is disposed tilted at an angle -α with respect to a plane perpendicular to the optical axis 10 with the X'-axis, which is parallel to the X-axis and passes through the optical axis, as the rotation axis. Here, the position of the second beam splitter 43 in the optical axis direction is closer to the spot than the first beam splitter 41 in Fig. 7, but it may be closer to the condenser lens 22 (laser oscillator) than the first beam splitter 41. The plane perpendicular to the optical axis 10 in Fig. 7 is a plane perpendicular to the optical axis 10 that includes only one point on the optical axis 10, the X-axis is a straight line on the plane perpendicular to the optical axis 10 that perpendicularly passes through the plane when the diagram of Fig. 7 is taken as a plane with the optical axis 10 as the origin, and the Y-axis is a straight line on the plane perpendicular to the optical axis 10 that is orthogonal to the X-axis on the plane when the diagram of Fig. 7 is taken as a plane with the optical axis 10 as the origin. In the present invention, the X-axis and the Y-axis are defined in the same way in other figures as above.

[0067] The first beam splitter 41 and the second beam splitter 43 have a function of splitting the incident laser beam into transmitted light and reflected light. In Fig. 7, the irradiation trajectory 15 of the laser beam shows the trajectory of the laser beam incident on the first beam splitter 41 and the second beam splitter 43 and the trajectory of the transmitted light between the first beam splitter 41 and the second beam splitter 43, and the reflected light between the first beam splitter 41 and the second beam splitter 43 is omitted. That is, in the third embodiment, the observation device 50 observes the transmitted light between the first beam splitter 41 and the second beam splitter 43. In this case, the transmittance of the laser beam through the first beam splitter 41 and the second beam splitter 43 when the incident angle of the laser beam to the first beam splitter 41 and the second beam splitter 43 is 45 degrees based on the optical surfaces of the first beam splitter 41 and the second beam splitter 43 is preferably 0.1% or more and 5.0% or less. This is because the energy intensity of the transmitted light component of the laser beam decreases with respect to the incident laser beam. Furthermore, it is preferable that the first beam splitter 41 and the second beam splitter 43 have the same change characteristic of the "transmittance at angles other than 45 degrees" of the incident angle of the laser beam to the first beam splitter 41 and the second beam splitter 43 based on the optical surfaces of the first beam splitter 41 and the second beam splitter 43 with respect to the "transmittance at 45 degrees". Unnecessary reflected light from the first beam splitter 41 and the second beam splitter 43 may be absorbed and dissipated by irradiating it onto a copper plate or the like whose surface has been blackened to facilitate absorption of the laser beam.

[0068] The thicknesses of the first beam splitter 41 and the second beam splitter 43 are not particularly limited as long as they can be used in the dimming mechanism 40, and the thicknesses of the first beam splitter 41 and the second beam splitter 43 may be the same or different.

[0069] Furthermore, in a plate-type beam splitter, refraction causes the transmitted light to shift relative to the optical axis 10 (the shift of the transmitted light is not shown in Figs. 7 and 8). However, since the light-reducing mechanism 40 is intended to measure the energy intensity distribution and image shape of the laser beam with the observation device 50, the shift of the transmitted light relative to the optical axis 10 does not pose a problem.

[0070] A beam splitter is usually designed to have a predetermined transmittance or reflectance when the incident angle to the beam splitter based on the optical surface of the beam splitter is 45°. When the incident angle of the laser beam to the beam splitter changes continuously from 45° to different values, the transmittance value of the beam splitter changes continuously to different values. In FIG. 7, as shown by the irradiation trajectory 15, the laser beam via the condenser lens 22 is incident on the first beam splitter 41 and the second beam splitter 43, so that the incident angle of the laser beam to the first beam splitter 41 and the second beam splitter 43 changes continuously in the direction of the Y axis described above. 2, if only one first beam splitter 41 is used as the attenuation mechanism 40, and assuming that the incident angle to the first beam splitter 41 is a minimum of 40° and a maximum of 50°, the transmittance ratio of the transmitted light at the minimum and maximum incident angles is 0.92 / 0.75=1.2. In this case, the energy intensity distribution of the laser beam at the spot cannot be measured correctly.

[0071] An enlarged view of the first beam splitter 41 and the second beam splitter 43 is shown in Fig. 8. In Fig. 8, the irradiation trajectory 15 of the laser beam shows the trajectory of the laser beam incident on the first beam splitter 41 and the second beam splitter 43 and the trajectory of the light transmitted through the first beam splitter 41 and the second beam splitter 43, and the reflected light from the first beam splitter 41 and the second beam splitter 43 is not shown. Here, the first beam splitter 41 is disposed tilted at an angle α within the above-mentioned range with respect to the plane 61 perpendicular to the optical axis 10 about the X-axis as the rotation axis, whereas the second beam splitter 43 is disposed tilted at an angle -α with respect to the plane 61 perpendicular to the optical axis 10 about the X'-axis as the rotation axis. The value of the incidence angle of the laser beam at the position of the optical axis 10 of the first beam splitter 41 with respect to the optical surface of the beam splitter is (90-α) when expressed as an angle smaller than 90°, as shown in FIG. 8. Similarly, the value of the incidence angle of the laser beam at the position of the optical axis 10 of the second beam splitter 43 with respect to the optical surface of the beam splitter is (90-α) when expressed as an angle smaller than 90°. For example, the incidence angle of the laser beam at the position of the upper end of the irradiation orbit 15 of the first beam splitter 41 with respect to the optical surface of the beam splitter is expressed as (90-α)-θ when the value of the incidence angle at the position of the optical axis 10 is used as the reference. The angle θ is the incidence angle of the laser beam at the position of the upper end of the irradiation orbit 15 with respect to the virtual line 62 parallel to the optical axis 10, that is, the angle of difference from the incidence angle at the position of the optical axis 10.

[0072] At this time, the transmitted light of the laser beam at the upper end position of the irradiation orbit 15, which is incident on the first beam splitter 41 at an angle of (90-α)-θ and transmitted therethrough, is incident on the second beam splitter 43 at an angle of (90-α)+θ. That is, the laser beam at the upper end position of the irradiation orbit 15 of the first beam splitter 41 is incident on the first beam splitter 41 at an incident angle shifted by an angle -θ from the incident angle at the position of the optical axis 10, and the transmitted light of the laser beam at the upper end position of the irradiation orbit 15 of the first beam splitter 41 is incident on the second beam splitter 43 at an incident angle shifted by an angle θ from the incident angle at the position of the optical axis 10. As described above, when the incident angle of the laser beam on the beam splitter changes continuously from 45° to different values, the value of the transmittance of the beam splitter changes continuously to different values. Therefore, the total transmittance of the transmitted light of the laser beam at the position of the upper end of the irradiation orbit 15 that has passed through the first beam splitter 41 and the second beam splitter 43 is approximately equal to the total transmittance of the transmitted light of the laser beam at the position of the optical axis 10. The above description has been given as an example of the transmitted light of the laser beam at the position of the upper end of the irradiation orbit 15 of the first beam splitter 41, but the same applies to the laser beam at any position on the irradiation orbit 15.

[0073] As described above, the third embodiment of the laser beam measurement device is configured by adding the second beam splitter 43 to the dimming mechanism 40 of the first embodiment of the laser beam measurement device, so that the energy intensity distribution of the laser beam incident on the dimming mechanism 40, measured by the observation device 50, can be measured correctly without being biased in the Y-axis direction.

[0074] Note that the first beam splitter 41 is tilted at an angle α around the X-axis as the rotation axis, and the second beam splitter 43 is tilted at an angle -α around the X'-axis as the rotation axis, so the incidence angle of the laser beam on the optical surfaces of the first beam splitter 41 and the second beam splitter 43 does not change in the direction of the X-axis.

[0075] Here, as shown in FIG. 8, the first beam splitter 41 is disposed with the X-axis as the rotation axis and tilted at an angle α in the range of 30 degrees to 60 degrees with respect to the plane perpendicular to the optical axis 10, and the second beam splitter 43 is disposed with the X'-axis, which is parallel to the X-axis and passes through the optical axis, as the rotation axis and tilted at an angle -α with respect to the plane perpendicular to the optical axis 10. When a plate-type beam splitter is disposed with a tilt with respect to the plane perpendicular to the optical axis in this way, if parallel light is incident on the beam splitter, the trajectory of the light emitted from the beam splitter shifts with respect to the incident light due to refraction. If focused light is incident on the beam splitter, in addition to the shift in trajectory, astigmatism occurs in which the emitted light is focused at the same focal length in the X-axis direction but is focused at a different focal length in the Y-axis direction. That is, the image of the transmitted light of the laser beam transmitted through the first beam splitter 41 and the second beam splitter 43 is distorted in the Y-axis direction due to astigmatism.

[0076] The image shape of the output data of the laser beam that is measured distorted in the Y-axis direction can be corrected by performing a numerical calculation using the calculation device 51. Below, a method of correcting the output data to a similar image shape to the image shape of the laser beam incident on the dimming mechanism 40 by performing a numerical calculation to correct the image shape of the output data in the Y-axis direction will be described, but as long as the image shape of the output data can be corrected in the Y-axis direction, the following description should not be construed as being limited to the above.

[0077] The first method is a method of correcting output data that can be used when the outer circumferential contour of the image shape on a plane perpendicular to the optical axis 10 of the laser beam incident on the dimming mechanism 40 is a circle. In this case, since the outer circumferential contour of the image shape on a plane perpendicular to the optical axis 10 of the laser beam incident on the dimming mechanism 40 is a circle, the ratio of the size in the X-axis direction to the size in the Y-axis direction of the outer circumferential contour of the image shape of the laser beam incident on the dimming mechanism 40 is 1:1. In this case, since the image on the X-axis of the image shape in the spot of the laser beam output from the dimming mechanism 40 is not distorted, the Y-axis position of the output data can be corrected using the ratio of the diameter of the image on the Y-axis to the diameter of the image on the X-axis as a reference.

[0078] For example, on the imaging surface of the observation device 50, the diameter value of the image in the X-axis direction is c, the diameter value of the image in the Y-axis direction is d, the X-axis coordinate value of the output data of an arbitrary position from the observation device 50 is x, and the Y-axis coordinate value is y. In this case, the data position after correction of the arbitrary position can be expressed as the X-axis coordinate value x and the Y-axis coordinate value (c / d)·y. That is, by using the arithmetic device 51 to perform a numerical calculation for correcting the coordinate position in the Y-axis direction of the output data from the observation device 50 as described above, corrected output data having an image shape similar to the image shape of the laser beam incident on the dimming mechanism 40 can be obtained. By displaying this corrected output data on a display device, it can be observed as the image shape at the spot. Therefore, it is preferable that the arithmetic device 51 has a numerical calculation function capable of performing the above-mentioned calculation.

[0079] The second method is an output data correction method that can be used when the outer circumferential contour of the image shape of the laser beam incident on the dimming mechanism 40 on a plane perpendicular to the optical axis 10 is a circle or a shape other than a circle. First, optical calculation is performed based on optical information of the optical system on the light source side (laser oscillator side) of the dimming mechanism 40, i.e., the image shape of the laser beam of the light source and optical information of the collimator lens 21 and the condenser lens 22, to obtain image shape data (primary data) of the laser beam at multiple spot positions (focal length positions) without including the dimming mechanism 40 in advance, and store the data in the storage device of the calculation device 51. Next, in the optical system including the dimming mechanism 40, a laser beam is irradiated, and image shape data (secondary data) of the laser beam is obtained from the observation device 50 at an arbitrary position set as the spot position.

[0080] Then, from the primary data, image shape data at the same spot position (focal length position) as that at which the secondary data was acquired is selected, and the value of the maximum image size in the X-axis direction of the image shape is e, and the value of the maximum image size in the Y-axis direction is f. Also, from the secondary data, the value of the maximum image size in the X-axis direction of the image shape is g, and the value of the maximum image size in the Y-axis direction is h. In this case, if the X-axis coordinate value of an arbitrary position of the output data from the observation device 50 is x, and the Y-axis coordinate value is y, the data position after correction of the arbitrary position can be expressed as the X-axis coordinate value x and the Y-axis coordinate value ((f·g) / (e·h))·y. That is, by using the calculation device 51 to perform a numerical calculation to correct the coordinate position in the Y-axis direction for the output data from the observation device 50 as described above, the corrected output data can be obtained as an image shape similar to the image shape of the laser beam incident on the dimming mechanism 40. By displaying this corrected output data on a display device, it can be observed as an image shape at the spot. Therefore, it is preferable that the arithmetic unit 51 has a numerical calculation function capable of performing the above-mentioned calculations.

[0081] In the above, when the diameter value of the image on the X-axis or Y-axis or the value of the maximum image size in the X-axis or Y-axis direction cannot be clearly determined, the diameter value of the image on the X-axis or Y-axis or the value of the maximum image size in the X-axis or Y-axis direction may be determined from the contour data of an image having a predetermined intensity (e.g., 10%) when the maximum value of the energy intensity of the laser beam measured by the observation device 50 is set to 100%.

[0082] That is, for the Y-axis direction of the output data, the coordinate position in the output data can be corrected by correcting the Y-axis direction coordinate position of the output data based on the ratio value between the maximum value of the image size in the X-axis direction of the image shape in the observation device 50 and the maximum value of the image size in the Y-axis direction. By using the above-mentioned first method, second method, etc., the image shape of the laser beam spot distorted in the Y-axis direction measured by the observation device 50 can be corrected to a correct image shape (an image shape similar to the image shape of the laser beam incident on the dimming mechanism 40) by using the calculation device 51.

[0083] In view of the above, in the third embodiment of the laser beam measurement device, it is preferable to provide a calculation device 51 having a numerical calculation function for correcting the energy intensity of the output data from the observation device 50 in the Y-axis direction and for correcting the coordinate position of the output data in the Y-axis direction.

[0084] In the configuration of the dimming mechanism 40 shown in Figure 8, if the energy intensity of the laser beam is insufficient to be incident on the observation device 50, an optical element such as an ND filter capable of dimming the laser beam may be placed between the beam splitter group of the first beam splitter 41 and the second beam splitter 43 and the observation device 50.

[0085] As described above, the third embodiment of the laser beam measurement device according to the present invention comprises: attenuation mechanism 40 having first beam splitter 41 and second beam splitter 43 on the spot side of laser beam irradiation optical unit 31; observation device 50 which measures information of the laser beam image formed at the spot position; and calculation device 51 which performs numerical calculations on output data of observation device 50 for correction; when arbitrary orthogonal coordinate axes having their origin on the optical axis 10 on a plane perpendicular to optical axis 10 are defined as the X-axis and Y-axis, first beam splitter 41 is arranged so as to be tilted at angle α in the range of 30 degrees or more and 60 degrees or less with respect to the plane perpendicular to optical axis 10, with the X-axis as the axis of rotation; and second beam splitter 43 is arranged so as to be tilted at angle -α with respect to the plane perpendicular to optical axis 10, with the X'-axis which is parallel to the X-axis and passes through the optical axis 10 as the axis of rotation. As a result, the power of the laser beam that can be incident is normally as large as 1 kW, and the energy intensity of the laser beam can be reduced to a level that does not damage the observation device 50 that acquires image data, such as an image sensor or a camera, and output from the attenuation mechanism 40. Then, the coordinate position of the output data in the Y-axis direction from the observation device 50 can be corrected using a calculation device 51 having a numerical calculation function. By using the output data after this correction, it is possible to measure the energy intensity distribution at the spot, which has an energy intensity distribution similar to the energy intensity distribution of the laser beam incident on the attenuation mechanism 40 and has an image shape similar to the image shape of the laser beam incident on the attenuation mechanism 40.

[0086] [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.

[0087] [Condenser lens] The condenser lens 22 is an optical element for condensing the laser beam, which has been converted into parallel light by the collimator lens 21, onto a spot.

[0088] [Beam splitter] There are cube-type and plate-type beam splitters, but the beam splitter according to the present invention is preferably a plate-type. The shape of the plate-type beam splitter is not particularly limited as long as it can be used in the light-reducing mechanism according to the present invention, and may be a square, polygonal, or circular shape. The plate-type beam splitter may be a polarizing type or a non-polarizing type. The cube-type is not preferable because it has multiple faces perpendicular to the incident direction of the laser beam, which generates return light of the laser beam to the laser oscillator (light source), making the laser oscillation unstable. The cube-type usually has a structure in which the inclined surfaces of two prisms are bonded together using a bonding resin. The cube-type has a larger volume than the plate-type. Therefore, the cube-type is not preferable because the resin used for bonding is easily denatured by the heat generated when the laser beam is incident, and the generated heat is more difficult to dissipate than the plate-type, making it more likely to break.

[0089] [Observation equipment] The observation device 50 is not particularly limited as long as it can observe the irradiation position and image shape of the laser beam and the energy intensity distribution of the laser beam as information on the image of the laser beam at the spot, and any observation device such as an image sensor such as a CCD or CMOS can be used. The observation device 50 is preferably capable of outputting the observation result as data. This is because the calculation device 51 can be used to perform numerical calculations on the output data of the observation device 50. In addition, it is preferable that the light-reducing mechanism 40 to which the observation device 50 is connected is detachable from the laser beam irradiation optical unit 31. When the light-reducing mechanism 40 is connected to the laser beam irradiation optical unit 31, the position of the imaging plane (observation point) of the observation device 50 is preferably located at the same place as the surface of the workpiece to be processed on which the spot is formed during laser processing. Furthermore, it is preferable that the center position of the imaging plane of the observation device 50 is located on the optical axis 10 and is the center of the processed part of the workpiece. This is because the position of the laser beam and the energy intensity distribution of the laser beam can be observed at the same position as the surface of the workpiece to be processed on which the spot is formed.

[0090] [Arithmetic device] The calculation device 51 can be any calculation device as long as it is programmable and can perform numerical calculations on the output data of the observation device 50 described above, but it is preferable that the calculation device is equipped with a storage device for storing data. This is because optical calculations can be performed based on optical information of the optical system arranged in the laser beam irradiation optical unit 31, and image shape data (primary data) of the laser beam at multiple spot positions (focal distance positions) can be acquired in advance and stored in a storage device. In addition, in an optical system including the light-reducing mechanism 40 in the laser beam irradiation optical unit 31, a laser beam is irradiated, and image shape data (secondary data) of the laser beam is acquired from the observation device 50 at an arbitrary position set as a spot position, and then image shape data at the same spot position (focal distance position) as that at which the secondary data was acquired can be selected from the primary data, and the coordinate position of the secondary data in the Y-axis direction can be corrected in the calculation device 51.

[0091] Furthermore, it is preferable that the arithmetic device 51 is connected to the observation device 50 by a connection cable 52 capable of sending and receiving electronic data. This is because control signals can be exchanged between the observation device 50 and the arithmetic device 51, and output data observed by the observation device 50 can be imported into the arithmetic device 51 for numerical calculation. Note that the connection cable 52 may be in any form as long as it is capable of performing the above-mentioned functions, and may be a cable using metal wires or optical fiber, or may be wireless communication such as radio communication or infrared communication that is not in the form of a cable.

[0092] Although the data corrected by the calculation device 51 is not shown in Figures 1, 4, and 7, by using a display device, the image shape of the laser beam and the energy intensity distribution of the laser beam can be displayed.

[0093] 2. Output data correction method The correction method for performing numerical calculations to correct the output data of the observation device 50 according to the present invention is a correction method that uses the functions of the calculation device 51 described in the first embodiment of the laser beam measurement device, the second embodiment of the laser beam measurement device, and the third embodiment of the laser beam measurement device to perform numerical calculations to correct the energy intensity of the output data in the Y-axis direction and to correct the coordinate position of the output data in the Y-axis direction.

[0094] [Y-axis energy intensity correction method] The energy intensity distribution of the output data of the laser beam measured with a bias in the Y-axis direction can be corrected by performing a numerical calculation using the calculation device 51. A method of correcting the output data to an energy intensity distribution similar to that of the laser beam incident on the light-attenuating mechanism 40 by performing a numerical calculation to correct the energy intensity distribution of the output data in the Y-axis direction will be described below, but the following description should not be interpreted as being limited to the above as long as the energy intensity distribution position of the output data can be corrected in the Y-axis direction. As described above, in the third embodiment of the laser beam measurement device, the light-attenuating mechanism 40 is composed of the first beam splitter 41 and the second beam splitter 43, so that the energy intensity distribution of the output data of the laser beam does not have a bias in the Y-axis direction, and correction of the output data of the laser beam regarding the bias in the Y-axis direction is not necessarily required.

[0095] In the first embodiment of the laser beam measurement device, first, incident angle dependency data of the transmittance of the first beam splitter 41 is acquired in advance. Furthermore, for example, at each data position on the imaging plane of the observation device 50 at the position of the spot, incident angle data of the transmittance of the first beam splitter 41 is acquired in advance by tracing the optical path of the light beam toward the emission point of the laser beam from the optical fiber 30 using a ray tracing method. These previously acquired data are stored in the storage device of the calculation device 51. Then, based on the incident angle data of the first beam splitter 41 at each data position on the imaging plane of the observation device 50 acquired in advance, the incident angle of the first beam splitter 41 is determined from the data position on the imaging plane of the observation device 50 for the output data of the observation device 50 due to the incidence of the laser beam. Furthermore, based on the incident angle dependency data of the transmittance of the first beam splitter 41 acquired in advance, the energy intensity value of the output data of the observation device 50 is corrected at other positions based on the transmittance of the incident angle to the first beam splitter 41 at the position of the optical axis 10 as a reference.

[0096] More specifically, for example, the following can be performed. The coordinate value of the X-axis of the output data at an arbitrary position from the observation device 50 is x, and the coordinate value of the Y-axis is y. Then, if the transmittance of the incident angle to the first beam splitter 41 at the position of the optical axis 10 is a, the transmittance of the incident angle to the first beam splitter 41 of the laser beam that reaches an arbitrary coordinate position (x, y) on the imaging surface of the observation device 50 is b, and the energy intensity value in the output data at the arbitrary coordinate position (x, y) of the observation device 50 is E, the corrected energy intensity value E' at the arbitrary coordinate position (x, y) of the observation device 50 can be corrected as E' = (a / b) · E. That is, for the Y-axis direction of the output data, the energy intensity in the output data can be corrected based on the transmittance value of the first beam splitter 41 corresponding to the incident angle of the laser beam to the first beam splitter 41. In this way, the energy intensity distribution of the laser beam, which is a distribution biased in the Y-axis direction measured by the observation device 50, can be corrected by the calculation device 51 to an energy intensity distribution similar to the energy intensity distribution of the laser beam incident on the dimming mechanism 40.

[0097] In the second embodiment of the laser beam measurement device, first, incident angle dependency data of the reflectance of the first beam splitter 42 is acquired in advance. Furthermore, for example, at each data position on the imaging plane of the observation device 50 at the position of the spot, the incident angle data of the first beam splitter 42 is acquired in advance by tracing the optical path of the light beam toward the emission point of the laser beam from the optical fiber 30 using a ray tracing method. These previously acquired data are stored in the storage device of the calculation device 51. Then, based on the incident angle data of the first beam splitter 42 at each data position on the imaging plane of the observation device 50 acquired in advance, the incident angle of the first beam splitter 42 is determined from the data position on the imaging plane of the observation device 50 for the output data of the observation device 50 due to the incidence of the laser beam. Furthermore, based on the incident angle dependency data of the reflectance of the first beam splitter 42 acquired in advance, the energy intensity value of the output data of the observation device 50 is corrected at other positions based on the reflectance of the incident angle to the first beam splitter 42 at the position of the optical axis 10 as a reference.

[0098] More specifically, for example, the following can be performed. The coordinate value of the X-axis of the output data of an arbitrary position from the observation device 50 is x, and the coordinate value of the Y-axis is y. Then, if the reflectance of the incident angle to the first beam splitter 42 at the position of the optical axis 10 is i, the reflectance of the incident angle to the first beam splitter 42 of the laser beam that reaches the coordinate position (x, y) of an arbitrary position on the imaging surface of the observation device 50 is j, and the energy intensity value in the output data of the arbitrary coordinate position (x, y) of the observation device 50 is E, the corrected energy intensity value E' of the arbitrary coordinate position (x, y) of the observation device 50 can be corrected as E' = (i / j) · E. That is, for the Y-axis direction of the output data, the energy intensity in the output data can be corrected based on the reflectance value of the first beam splitter 42 corresponding to the incident angle of the laser beam to the first beam splitter 42. In this way, the energy intensity distribution of the laser beam, which is a distribution biased in the Y-axis direction measured by the observation device 50, can be corrected by the calculation device 51 to an energy intensity distribution similar to the energy intensity distribution of the laser beam incident on the dimming mechanism 40.

[0099] [How to correct the coordinate position in the Y-axis direction] The image shape of the output data of the laser beam that is measured distorted in the Y-axis direction can be corrected by performing a numerical calculation using the calculation device 51. Below, a method of correcting the output data to a similar image shape to the energy intensity distribution of the laser beam incident on the light-attenuating mechanism 40 by performing a numerical calculation to correct the image shape of the output data in the Y-axis direction in the first embodiment of the laser beam measurement device and the third embodiment of the laser beam measurement device will be described, but the following description should not be interpreted as being limited to the above as long as the image shape of the output data can be corrected in the Y-axis direction. As described above, in the second embodiment of the laser beam measurement device, since the light-attenuating mechanism 40 does not cause astigmatism, the image shape of the output data of the laser beam does not distort in the Y-axis direction, and correction of the output data of the laser beam regarding the distortion in the Y-axis direction is not necessarily required.

[0100] The first method is a method of correcting output data that can be used when the outer circumferential contour of the image shape on a plane perpendicular to the optical axis 10 of the laser beam incident on the dimming mechanism 40 is a circle. In this case, since the outer circumferential contour of the image shape on a plane perpendicular to the optical axis 10 of the laser beam incident on the dimming mechanism 40 is a circle, the ratio of the size in the X-axis direction to the size in the Y-axis direction of the outer circumferential contour of the image shape of the laser beam incident on the dimming mechanism 40 is 1:1. At this time, since the image on the X-axis of the image shape in the spot of the laser beam output from the dimming mechanism 40 is not distorted, the Y-axis position of the output data can be corrected using the ratio of the diameter of the image on the Y-axis to the diameter of the image on the X-axis as a reference. For example, on the imaging surface of the observation device 50, the diameter value of the image in the X-axis direction is c, the diameter value of the image in the Y-axis direction is d, and the X-axis coordinate value of the output data at an arbitrary position from the observation device 50 is x and the Y-axis coordinate value is y. At this time, the corrected data position of the arbitrary position can be expressed as x on the X-axis and (c / d)·y on the Y-axis. That is, by using the calculation device 51 to perform a numerical calculation to correct the coordinate position of the output data from the observation device 50 in the Y-axis direction as described above, corrected output data having an image shape similar to the image shape of the laser beam incident on the attenuation mechanism 40 can be obtained. By displaying this corrected output data on a display device, it can be observed as the image shape of the spot.

[0101] The second method is an output data correction method that can be used when the outer contour of the image shape of the laser beam incident on the dimming mechanism 40 on a plane perpendicular to the optical axis 10 is a circle or a shape other than a circle. First, optical calculation is performed based on optical information of the optical system on the light source side of the dimming mechanism 40, i.e., the image shape of the laser beam from the light source and optical information of the collimator lens 21 and the condenser lens 22, to obtain image shape data (primary data) of the laser beam at multiple spot positions (focal length positions) without including the dimming mechanism 40 in advance, and store the data in the storage device of the calculation device 51. Next, in the optical system including the dimming mechanism 40, a laser beam is irradiated, and image shape data (secondary data) of the laser beam is obtained from the observation device 50 at an arbitrary position set as the spot position.

[0102] Then, from the primary data, image shape data at the same spot position (focal length position) as that at which the secondary data was acquired is selected, and the value of the maximum image size in the X-axis direction of the image shape is e, and the value of the maximum image size in the Y-axis direction is f. Also, from the secondary data, the value of the maximum image size in the X-axis direction of the image shape is g, and the value of the maximum image size in the Y-axis direction is h. In this case, if the X-axis coordinate value of an arbitrary position of the output data from the observation device 50 is x, and the Y-axis coordinate value is y, the data position after correction of the arbitrary position can be expressed as the X-axis coordinate value x and the Y-axis coordinate value ((f·g) / (e·h))·y. That is, by using the calculation device 51 to perform a numerical calculation to correct the coordinate position in the Y-axis direction for the output data from the observation device 50 as described above, the corrected output data can be obtained as an image shape similar to the image shape of the laser beam incident on the dimming mechanism 40. By displaying this corrected output data on a display device, it can be observed as an image shape at the spot.

[0103] In the above, when the diameter value of the image on the X-axis or Y-axis or the value of the maximum image size in the X-axis or Y-axis direction cannot be clearly determined, the diameter value of the image on the X-axis or Y-axis or the value of the maximum image size in the X-axis or Y-axis direction may be determined from the contour data of an image having a predetermined intensity (e.g., 10%) when the maximum value of the energy intensity of the laser beam measured by the observation device 50 is set to 100%.

[0104] That is, for the Y-axis direction of the output data, the coordinate position in the output data can be corrected by correcting the Y-axis direction coordinate position of the output data based on the ratio value between the maximum value of the image size in the X-axis direction of the image shape in the observation device 50 and the maximum value of the image size in the Y-axis direction. By using the above-mentioned first method, second method, etc., the image shape of the laser beam spot distorted in the Y-axis direction measured by the observation device 50 can be corrected to a correct image shape (an image shape similar to the image shape of the laser beam incident on the dimming mechanism 40) by using the calculation device 51.

[0105] 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. The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples. EXAMPLES

[0106] In Example 1, the configuration of the first embodiment 1 of the laser beam measurement device shown in FIG. 1, which is the first embodiment of the laser beam measurement device, was used. A condenser lens 22 equipped with a ring-shaped conversion function was used so that the image shape at the spot became ring-shaped. A plate-type first beam splitter 41 was used, which had a thickness of 3 mm and a transmittance characteristic shown in FIG. 2. The first beam splitter 41 was placed at an angle of 45 degrees with the X-axis as the rotation axis. In the first embodiment 1 of the laser beam measurement device, the image shape is distorted in the Y-axis direction in the output data of the observation device 50, and the energy intensity distribution is biased in the Y-axis direction. This was corrected by the following method.

[0107] The image shape of the output data of the laser beam distorted in the Y-axis direction and measured is a circle on the plane perpendicular to the optical axis 10 of the laser beam incident on the dimming mechanism 40, so the ratio of the size in the X-axis direction to the size in the Y-axis direction of the image shape of the laser beam incident on the dimming mechanism 40 is 1:1. At this time, the image on the X-axis of the image shape of the spot of the laser beam output from the dimming mechanism 40 is not distorted. Then, on the imaging surface of the observation device 50, the diameter value of the image in the X-axis direction is c, the diameter value of the image in the Y-axis direction is d, and the X-axis coordinate value of the output data of an arbitrary position from the observation device 50 is x, and the Y-axis coordinate value is y. At this time, the data position after correction of the arbitrary position can be corrected to have the X-axis coordinate value x and the Y-axis coordinate value (c / d)·y. In this way, the image shape distorted in the Y-axis direction measured by the observation device 50 is corrected to an image shape similar to the image shape of the laser beam incident on the dimming mechanism 40 by the calculation device 51.

[0108] Furthermore, the energy intensity distribution of the output data of the laser beam measured with a bias in the Y-axis direction was corrected as follows. First, at each data position on the imaging plane of the observation device 50 at the spot position, the optical path of the light beam was traced toward the emission point of the laser beam from the optical fiber 30 using a ray tracing method, thereby obtaining the incident angle data of the first beam splitter 41 in advance. This makes it possible to specify the incident angle of the output data of the observation device 50 to the first beam splitter 41 from the data position on the imaging plane of the observation device 50. Here, the X-axis coordinate value of the output data of an arbitrary position from the observation device 50 is set to x, and the Y-axis coordinate value is set to y. Then, if the transmittance of the incident angle to the first beam splitter 41 at the position of the optical axis 10 is a, the transmittance of the incident angle to the first beam splitter 41 of the laser beam that reaches an arbitrary coordinate position (x, y) on the imaging surface of the observation device 50 is b, and the energy intensity value in the output data of the arbitrary coordinate position (x, y) of the observation device 50 is E, the corrected energy intensity value E' of the arbitrary coordinate position (x, y) of the observation device 50 can be corrected as E' = (a / b) · E. In this way, the energy intensity distribution of the laser beam, which is a distribution biased in the Y-axis direction measured by the observation device 50, is corrected by the calculation device 51 to an energy intensity distribution similar to the energy intensity distribution of the laser beam incident on the attenuation mechanism 40.

[0109] The energy intensity distribution of the image at the spot corrected in this manner is shown in Fig. 9. Fig. 9(a) shows the energy intensity distribution on the X axis of the image at the spot, with the horizontal axis indicating the coordinate position on the X axis and the vertical axis indicating the energy intensity. Fig. 9(b) shows the energy intensity distribution on the Y axis of the image at the spot, with the vertical axis indicating the coordinate position on the Y axis and the horizontal axis indicating the energy intensity. From Fig. 9, it was confirmed that the energy intensity distribution of the output data obtained from the laser beam measurement device of Example 1 was corrected to an unbiased state.

[0110] Next, the image shape results for the spot are shown in Figure 10. The left side of the figure shows the focal position corresponding to underfocus, and the right side of the figure shows the focal position corresponding to overfocus. Figure 10 shows that the image shape for the spot is circular, and it can be confirmed that the image shape has been corrected. EXAMPLES

[0111] In Example 2, the configuration of the second embodiment 2 of the laser beam measurement device shown in FIG. 4, which is the second embodiment of the laser beam measurement device, was used. A condenser lens 22 equipped with an annular conversion function was used so that the image shape at the spot became annular. A plate-type first beam splitter 42 having a thickness of 3 mm and a reflectance characteristic shown in FIG. 5 was used. The first beam splitter 42 was placed at an angle of 45 degrees with the X-axis as the rotation axis. In the second embodiment 2 of the laser beam measurement device, the energy intensity distribution is biased in the Y-axis direction in the output data of the observation device 50. This was corrected by the following method.

[0112] The energy intensity distribution of the output data of the laser beam measured with a bias in the Y-axis direction was corrected as follows. First, at each data position on the imaging plane of the observation device 50 at the spot position, the optical path of the light beam was traced toward the emission point of the laser beam from the optical fiber 30 using a ray tracing method, thereby obtaining the incident angle data of the first beam splitter 42 in advance. This makes it possible to specify the incident angle of the output data of the observation device 50 to the first beam splitter 42 from the data position on the imaging plane of the observation device 50. Here, the X-axis coordinate value of the output data of an arbitrary position from the observation device 50 is set to x, and the Y-axis coordinate value is set to y. Then, assuming that the reflectance at the angle of incidence on the first beam splitter 42 at the position of the optical axis 10 is i, the reflectance at the angle of incidence on the first beam splitter 42 of the laser beam that reaches an arbitrary coordinate position (x, y) on the imaging surface of the observation device 50 is j, and the energy intensity value in the output data of the arbitrary coordinate position (x, y) of the observation device 50 is E, the corrected energy intensity value E' at the arbitrary coordinate position (x, y) of the observation device 50 can be corrected as E' = (i / j) · E. In this way, the energy intensity distribution of the laser beam, which is a distribution biased in the Y-axis direction measured by the observation device 50, is corrected by the calculation device 51 to an energy intensity distribution similar to the energy intensity distribution of the laser beam incident on the attenuation mechanism 40.

[0113] The energy intensity distribution of the image at the spot corrected in this manner is shown in Fig. 11. Fig. 11(a) shows the energy intensity distribution on the X axis of the image at the spot, with the horizontal axis indicating the coordinate position on the X axis and the vertical axis indicating the energy intensity. Fig. 11(b) shows the energy intensity distribution on the Y axis of the image at the spot, with the vertical axis indicating the coordinate position on the Y axis and the horizontal axis indicating the energy intensity. From Fig. 11, it was confirmed that the energy intensity distribution of the output data obtained from the laser beam measurement device of Example 2 was corrected to be unbiased.

[0114] Next, the result of the image shape at the spot is shown in Fig. 12. The left side of the figure shows the focal position corresponding to underfocus, and the right side of the figure shows the focal position corresponding to overfocus. From Fig. 12, it was confirmed that the image shape at the spot was circular. This is because Example 2 uses the reflected light of the first beam splitter 42, and no astigmatism occurs in the reflected light, so that an image shape similar to the image shape of the laser beam incident on the dimming mechanism 40 can be obtained without correcting the output data. EXAMPLES

[0115] In Example 3, the configuration of the third embodiment 3 of the laser beam measurement device shown in FIG. 7, which is the third embodiment of the laser beam measurement device, was used. A condenser lens 22 equipped with an annular conversion function was used so that the image shape at the spot became annular. Also, plate-type first beam splitter 41 and second beam splitter 43 were used, which had a thickness of 3 mm and had the transmittance characteristics shown in FIG. 2. The first beam splitter 41 was arranged at an inclination of 45 degrees with the X-axis as the rotation axis, and the second beam splitter 43 was arranged at an inclination of -45 degrees with the X'-axis as the rotation axis. In the third embodiment 3 of the laser beam measurement device, the image shape is distorted in the Y-axis direction in the output data of the observation device 50. This was corrected by the following method.

[0116] The image shape of the output data of the laser beam distorted in the Y-axis direction and measured is a circle on the plane perpendicular to the optical axis 10 of the laser beam incident on the dimming mechanism 40, so the ratio of the size in the X-axis direction to the size in the Y-axis direction of the image shape of the laser beam incident on the dimming mechanism 40 is 1:1. At this time, the image on the X-axis of the image shape of the spot of the laser beam output from the dimming mechanism 40 is not distorted. Then, on the imaging surface of the observation device 50, the diameter value of the image in the X-axis direction is c, the diameter value of the image in the Y-axis direction is d, and the X-axis coordinate value of the output data of an arbitrary position from the observation device 50 is x, and the Y-axis coordinate value is y. At this time, the data position after correction of the arbitrary position can be corrected to have the X-axis coordinate value x and the Y-axis coordinate value (c / d)·y. In this way, the image shape distorted in the Y-axis direction measured by the observation device 50 is corrected to an image shape similar to the image shape of the laser beam incident on the dimming mechanism 40 by the calculation device 51.

[0117] The energy intensity distribution of the image at the spot corrected in this manner is shown in FIG. 13. FIG. 13(a) shows the energy intensity distribution on the X axis of the image at the spot, with the horizontal axis showing the coordinate position on the X axis and the vertical axis showing the energy intensity. FIG. 13(b) shows the energy intensity distribution on the Y axis of the image at the spot, with the vertical axis showing the coordinate position on the Y axis and the horizontal axis showing the energy intensity. From FIG. 13, it was confirmed that the energy intensity distribution was not biased. This is because Example 3 uses the attenuation mechanism 40 of the third embodiment of the laser beam measurement device, and therefore an energy intensity distribution similar to the energy intensity distribution of the laser beam incident on the attenuation mechanism 40 can be obtained without correcting the output data.

[0118] Next, the result of the image shape at the spot is shown in FIG. 14. The left side of the figure shows the focal position corresponding to underfocus, and the right side of the figure shows the focal position corresponding to overfocus. From FIG. 14, it was confirmed that the image shape at the spot was circular, and the image shape was corrected. Comparative Example

[0119] Comparative Example 1 In Comparative Example 1, a configuration was used in which the calculation device 51 was removed from the first embodiment 1 of the laser beam measurement device shown in FIG. 1. A condenser lens 22 equipped with a circular conversion function was used so that the image shape at the spot became circular. A plate-type first beam splitter 41 having a thickness of 3 mm and the transmittance characteristics shown in FIG. 2 was used. The first beam splitter 41 was disposed at an angle of 45 degrees with the X-axis as the rotation axis. No correction was made to the output data of the observation device 50.

[0120] The results of the energy intensity distribution of the image at the spot are shown in Fig. 15. Fig. 15(a) shows the energy intensity distribution on the X axis of the image at the spot, with the horizontal axis showing the coordinate position on the X axis and the vertical axis showing the energy intensity. Fig. 15(b) shows the energy intensity distribution on the Y axis of the image at the spot, with the vertical axis showing the coordinate position on the Y axis and the horizontal axis showing the energy intensity. From Fig. 15, it was confirmed that the energy intensity distribution was biased for the output data obtained from the laser beam measurement device of Comparative Example 1.

[0121] Next, the image shape at the spot is shown in Figure 16. The horizontal position indicates the focal position corresponding to underfocus on the left side of the figure and overfocus on the right side of the figure. From Figure 16, it was confirmed that the image shape at the spot is elliptical, and the image shape is distorted in the Y-axis direction.

[0122] Comparative Example 2 In Comparative Example 2, a configuration was used in which the calculation device 51 was removed from the second embodiment 2 of the laser beam measurement device shown in FIG. 4. A condenser lens 22 equipped with a circular conversion function was used so that the image shape at the spot became circular. A plate-type first beam splitter 42 having a thickness of 3 mm and the reflectance characteristics shown in FIG. 5 was used. The first beam splitter 42 was disposed at an angle of 45 degrees with the X-axis as the rotation axis. No correction was made to the output data of the observation device 50.

[0123] The results of the energy intensity distribution of the image at the spot are shown in Fig. 17. Fig. 17(a) shows the energy intensity distribution on the X axis of the image at the spot, with the horizontal axis indicating the coordinate position on the X axis and the vertical axis indicating the energy intensity. Fig. 17(b) shows the energy intensity distribution on the Y axis of the image at the spot, with the vertical axis indicating the coordinate position on the Y axis and the horizontal axis indicating the energy intensity. From Fig. 17, it was confirmed that the energy intensity distribution was biased for the output data obtained from the laser beam measurement device of Comparative Example 2.

[0124] Next, the image shape at the spot is shown in Figure 18. The horizontal position indicates the focal position corresponding to underfocus on the left side of the figure and overfocus on the right side of the figure. From Figure 18, it was confirmed that the image shape at the spot is circular and the image shape is not distorted.

[0125] Comparative Example 3 In Comparative Example 3, a configuration was used in which the calculation device 51 was removed from the third embodiment 3 of the laser beam measurement device shown in FIG. 7. A condenser lens 22 equipped with a ring-shaped conversion function was used so that the image shape at the spot was ring-shaped. The plate-type first beam splitter 41 and second beam splitter 43 were 3 mm thick and had the transmittance characteristics shown in FIG. 2. The first beam splitter 41 was tilted 45 degrees around the X-axis as the rotation axis, and the second beam splitter 43 was tilted -45 degrees around the X'-axis as the rotation axis. No correction was made to the output data of the observation device 50.

[0126] The results of the energy intensity distribution of the image at the spot are shown in Fig. 19. Fig. 19(a) shows the energy intensity distribution on the X axis of the image at the spot, with the horizontal axis indicating the coordinate position on the X axis and the vertical axis indicating the energy intensity. Fig. 19(b) shows the energy intensity distribution on the Y axis of the image at the spot, with the vertical axis indicating the coordinate position on the Y axis and the horizontal axis indicating the energy intensity. From Fig. 19, it was confirmed that the energy intensity distribution was not biased for the output data obtained from the laser beam measurement device of Comparative Example 1.

[0127] Next, the image shape at the spot is shown in Figure 20. The horizontal position indicates the focal position corresponding to underfocus on the left side of the figure and overfocus on the right side of the figure. From Figure 20, it was confirmed that the image shape at the spot is elliptical, and the image shape is distorted in the Y-axis direction. [Industrial Applicability]

[0128] The laser beam measurement device according to the present invention can measure the image shape and energy intensity distribution of the laser beam spot by attenuating the laser beam to an extent that does not damage devices that acquire image data, such as image sensors and cameras, even if the laser beam has a high energy intensity. Furthermore, the laser beam measurement device can correct the energy intensity and coordinate position of the output data from the observation device to perform accurate measurement, even in the case of focused light whose incidence angle varies depending on the incidence position. In other words, the laser beam measurement device according to the present invention is suitable for measuring the image shape and energy intensity distribution of the laser beam at the spot in a laser processing device that processes an object by irradiating a laser beam. [Explanation of symbols]

[0129] 1. First embodiment of laser beam measurement device 2. Second embodiment of laser beam measurement device 3. Third embodiment of laser beam measurement device 10 Optical axis 15 Irradiation trajectory 21 Collimating lens 22 Condenser lens 30 Optical Fiber 31 Laser beam irradiation optical unit 40 Dimming mechanism 41 First beam splitter 42 First beam splitter 43 2nd beam splitter 50 Observation Equipment 51 Arithmetic unit 52 Connection cable 61 Surface perpendicular to the optical axis 10 62 Imaginary line parallel to optical axis 10 63 Surface perpendicular to optical axis 10 64 Imaginary line parallel to optical axis 10

Claims

1. A laser beam measurement device for a laser beam irradiated from a laser beam irradiation optical unit for forming a spot on a processing object and irradiating the laser beam to perform laser processing, comprising: a plate-type first beam splitter, an observation device that reads an image of the spot formed by transmitted light or reflected light of the laser beam incident on the first beam splitter, and a calculation device that performs numerical calculations on output data of the observation device to perform correction, a laser beam measurement device characterized in that, when arbitrary orthogonal coordinate axes having an origin on a plane perpendicular to an optical axis of the laser beam irradiation optical unit at the optical axis are defined as X-axis and Y-axis, the first beam splitter is disposed tilted at an angle α in the range of 30 degrees or more and 60 degrees or less with respect to a plane perpendicular to the optical axis, with the X-axis as a rotation axis.

2. 2. The laser beam measurement device according to claim 1, further comprising a plate-type second beam splitter, the second beam splitter being arranged at an angle -α with respect to a plane perpendicular to the optical axis, with an X'-axis that is parallel to the X-axis and passes through the optical axis as a rotation axis, and the spot being formed by transmitted light of the laser beam incident on the first beam splitter and the second beam splitter.

3. 2. The laser beam measurement device according to claim 1, wherein the first beam splitter has a transmittance of 0.1% or more and 5.0% or less when the incident angle of the laser beam is 45 degrees, or a reflectance of 0.1% or more and 5.0% or less when the incident angle of the laser beam is 45 degrees.

4. 3. The laser beam measurement device according to claim 2, wherein the first beam splitter and the second beam splitter have a transmittance of 0.1% or more and 5.0% or less when the incident angle of the laser beam is 45 degrees.

5. When the image of the spot is formed by the transmitted light, the calculation device correcting the energy intensity of the output data in a Y-axis direction of the output data based on a transmittance value of the first beam splitter corresponding to an incident angle of the laser beam to the first beam splitter; correcting a coordinate position in the Y-axis direction of the output data based on a ratio value between a maximum value of an image size in the X-axis direction of an image shape in the observation device and a maximum value of an image size in the Y-axis direction of the output data; 2. The laser beam measurement device according to claim 1, further comprising a numerical calculation function.

6. When the image of the spot is formed by the reflected light, the calculation device correcting the energy intensity of the output data in a Y-axis direction of the output data based on a reflectance value of the first beam splitter corresponding to an incident angle of the laser beam to the first beam splitter; 2. The laser beam measurement device according to claim 1, further comprising a numerical calculation function.

7. The computing device includes: correcting a coordinate position in the Y-axis direction of the output data based on a ratio value between a maximum value of an image size in the X-axis direction of an image shape in the observation device and a maximum value of an image size in the Y-axis direction of the output data; 3. The laser beam measurement device according to claim 2, further comprising a numerical calculation function.

8. 2. A method for correcting output data in a calculation device, which performs numerical calculations to correct output data of an observation device that reads an image of a spot formed by transmitted light of a laser beam incident on a first beam splitter in the laser beam measurement device according to claim 1, comprising the steps of: performing a numerical calculation to correct the energy intensity of the output data in a Y-axis direction of the output data based on a transmittance value of the first beam splitter corresponding to an incident angle of the laser beam to the first beam splitter; performing a numerical calculation to correct a coordinate position in the output data by correcting a coordinate position in the Y-axis direction of the output data based on a ratio value between a maximum value of an image size in the X-axis direction of an image shape in the observation device and a maximum value of an image size in the Y-axis direction; 23. A method for correcting output data comprising the steps of:

9. 2. A method for correcting output data in a calculation device, which performs numerical calculations to correct output data of an observation device that reads an image of a spot formed by reflected light of a laser beam incident on a first beam splitter in the laser beam measurement device according to claim 1, comprising the steps of: performing a numerical calculation to correct the energy intensity of the output data in a Y-axis direction of the output data based on a reflectance value of the first beam splitter corresponding to an incident angle of the laser beam to the first beam splitter; 23. A method for correcting output data comprising the steps of:

10. 3. A method for correcting output data in a calculation device in the laser beam measurement device according to claim 2, the method comprising the steps of: calculating a numerical value of output data of an observation device that reads an image of a spot formed by transmitted light of a laser beam incident on a first beam splitter and a second beam splitter; performing a numerical calculation to correct a coordinate position in the output data by correcting a coordinate position in the Y-axis direction of the output data based on a ratio value between a maximum value of an image size in the X-axis direction of an image shape in the observation device and a maximum value of an image size in the Y-axis direction; 23. A method for correcting output data comprising the steps of:

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