TWI777625B - Laser power measurement device - Google Patents

Abstract

In order to provide a laser power measurement device that can suppress energy loss and achieve space saving. The first sensor, which has a light-receiving surface on which the laser beam is incident, measures the average power of the laser beam incident on the light-receiving surface. The second sensor, which is arranged at the position where the scattered light from the light-receiving surface of the first sensor is incident, measures the peak power of the incident laser beam.

Description

Laser power measurement device

The present invention relates to a laser power measuring device. This application claims priority based on Japanese Patent Application No. 2020-115642 filed on July 3, 2020. The entire contents of the Japanese application are incorporated in this specification by reference.

In order to detect the output variation of the laser oscillator or the generation of weak pulses whose peak power does not reach the specified value, a power meter and a photodetector are arranged at the outlet of the laser oscillator. Even while the laser beam is incident on the object to be processed, in order to detect output fluctuations or weak pulses, a beam splitter is arranged on the path of the laser beam, and a part of the laser beam is guided to the power meter and photodetector device. The energy of the laser beam branched by the beam splitter is usually about 2%~5% of the energy of the original laser beam.

The following Patent Document 1 discloses a laser control method that uses a power meter and a photodetector to detect a laser beam output from a laser oscillator, thereby achieving stabilization of the laser output. [Prior Art Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2010-147105

[Problems to be Solved by Invention]

In order to guide the laser beam to the power meter and photodetector, two beam splitters are arranged on the path of the laser beam, resulting in a total energy loss of about 4% to 5%. Also, a space for arranging the two beam splitters is required.

An object of the present invention is to provide a laser power measurement device capable of suppressing energy loss and achieving space saving. [Technical means to solve problems]

According to an aspect of the present invention, a laser power measurement device is provided, which has: The first sensor has a light-receiving surface on which the laser beam is incident, and measures the average power of the laser beam incident on the light-receiving surface; and The second sensor is arranged at a position where scattered light from the light-receiving surface of the first sensor is incident, and measures the peak power of the incident laser beam. [Effect of invention]

Since the scattered light from the light-receiving surface of the first sensor is incident on the second sensor, it is not necessary to arrange a beam splitter for allowing a part of the laser beam to be incident on the second sensor. Since the number of beam splitters can be reduced, energy loss can be suppressed and space saving can be achieved.

Referring to FIG. 1 to FIG. 6F , the laser power measurement device according to an embodiment will be described. FIG. 1 is a schematic diagram of a laser processing apparatus equipped with a laser power measuring apparatus 50 according to this embodiment. The laser processing device includes a laser oscillator 12 , a laser power measuring device 50 , a processing device 80 and a laser power source 60 .

The laser oscillator 12 is supported on the stage 11 , and the stage 11 is fixed to the common base 100 . The processing apparatus 80 includes a beam shaping optical system 81 and a stage 82 . The object to be processed 90 is held on the stage 82 . The beam shaping optical system 81 and the stage 82 are fixed to the common base 100 . The laser power measurement device 50 is supported by, for example, an optical table shared with the beam shaping optical system 81 . The common base 100 is tied to the floor, for example.

The laser oscillator 12 outputs a pulsed laser beam. As the laser oscillator 12, for example, a carbon dioxide laser oscillator is used. The pulsed laser beam output from the laser oscillator 12 is shaped by the beam shaping optical system 81 to shape the beam profile, and is incident on the object 90 to be processed. The laser power measuring device 50 measures the average power and peak power of the pulsed laser beam output from the laser oscillator 12, and outputs a voltage signal corresponding to the power. Average power is the power obtained by multiplying the pulse energy by the pulse repetition frequency. Peak power is approximated by dividing the pulse energy by the pulse width. The voltage signal output from the laser power measuring device 50 is input to the laser power source 60 through the amplifier 59 .

The laser power source 60 includes a control device 61 and a discharge voltage applying device 62 . The control device 61 has a function of integrating the measured value of the peak power for a certain period of time, and controlling the magnitude of the discharge voltage based on the integrated value. The discharge voltage applying device 62 applies the discharge voltage to the discharge electrodes of the laser oscillator 12 according to the magnitude of the discharge voltage controlled by the control device 61 .

FIG. 2 is a cross-sectional view including the optical axis of the laser oscillator 12 . The laser oscillator 12 includes a chamber 15 that accommodates the laser dielectric gas, the optical resonator 20 and the like. The laser medium gas is contained in the chamber 15 . The inner space of the chamber 15 is divided into an optical chamber 16 located relatively on the upper side and a blower chamber 17 relatively located on the lower side. The optical chamber 16 and the blower chamber 17 are partitioned by upper and lower partition plates 18 . In addition, the upper and lower partition plates 18 are provided with openings for allowing the laser medium gas to flow between the optical chamber 16 and the blower chamber 17 . The bottom plate 19 of the optical chamber 16 protrudes from the side wall of the blower chamber 17 in the direction of the optical axis 20A of the optical resonator 20 .

The bottom plate 19 of the chamber 15 is supported by the stage 11 ( FIG. 1 ) at four support locations 45 . The four support parts 45 are arranged at positions corresponding to the four vertices of the rectangle in a plan view.

A pair of discharge electrodes 21 and a pair of resonator mirrors 25 are arranged in the optical chamber 16 . The pair of discharge electrodes 21 are respectively fixed to the electrode case 22 . A discharge voltage is applied to the discharge electrode 21 from a discharge voltage application device 62 ( FIG. 1 ). The pair of electrode boxes 22 are supported by the bottom plate 19 via a plurality of electrode supporting members 23 . The pair of discharge electrodes 21 are arranged at intervals in the vertical direction, and define a discharge region 24 therebetween. The discharge electrode 21 excites the laser dielectric gas by causing the discharge region 24 to discharge. A pair of resonator mirrors 25 constitute an optical resonator 20 having an optical axis 20A passing through the discharge region 24 . Hereinafter, as described with reference to FIG. 3 , the laser dielectric gas flows through the discharge region 24 in a direction perpendicular to the paper surface of FIG. 2 .

A pair of resonator mirrors 25 are fixed to a common resonator base 26 disposed in the optical chamber 16 . The resonator base 26 is a plate-like member whose long side is in the direction of the optical axis 20A, and is supported by the bottom plate 19 via a plurality of optical resonator support members 27 .

A light-transmitting window 28 through which the laser beam penetrates is installed at the intersection of the extension line extending the optical axis 20A of the optical resonator 20 in one direction (leftward in FIG. 1 ) and the wall surface of the optical chamber 16 . The laser beam excited in the optical resonator 20 penetrates the light-transmitting window 28 and is emitted to the outside.

A blower 29 is arranged in the blower chamber 17 . The blower 29 circulates the laser medium gas between the optical chamber 16 and the blower chamber 17 .

FIG. 3 is a cross-sectional view perpendicular to the optical axis 20A ( FIG. 2 ) of the laser oscillator 12 according to the embodiment. As already described with reference to FIG. 2 , the inner space of the chamber 15 is divided into the upper optical chamber 16 and the lower blower chamber 17 by the upper and lower partition plates 18 . A pair of discharge electrodes 21 and a resonator base 26 are arranged in the optical chamber 16 . The pair of discharge electrodes 21 are respectively fixed to the electrode case 22 . The electrode box 22 is supported by the bottom plate 19 ( FIG. 2 ) of the chamber 15 via a plurality of electrode support members 23 . A discharge region 24 is defined between the pair of discharge electrodes 21 . The resonator base 26 is supported by the bottom plate 19 ( FIG. 2 ) of the chamber 15 via a plurality of optical resonator support members 27 . Since the electrode supporting member 23 and the optical resonator supporting member 27 are arranged at positions deviating from the cross section shown in FIG. 3 , the electrode supporting member 23 and the optical resonator supporting member 27 are indicated by dotted lines in FIG. 3 .

A partition plate 40 is arranged in the optical chamber 16 . The partition plate 40 defines a first gas flow path 41 from the opening 18A provided in the upper and lower partition plates 18 to the discharge region 24 , and from the discharge region 24 to the other opening 18B provided in the upper and lower partition plates 18 . The second gas flow path 42 . The laser dielectric gas flows through the discharge region 24 in a direction orthogonal to the optical axis 20A (FIG. 2). The discharge direction is orthogonal to both the direction in which the laser medium gas flows and the optical axis 20A. The blower chamber 17 , the first gas flow path 41 , the discharge region 24 , and the second gas flow path 42 form a circulation path in which the laser medium gas circulates. The blower 29 generates a laser medium gas flow indicated by an arrow so as to circulate the laser medium gas in the circulation path.

The heat exchanger 43 is accommodated in the circulation path in the blower chamber 17 . The laser medium gas heated in the discharge region 24 is cooled by passing through the heat exchanger 43 , and the cooled laser medium gas is supplied to the discharge region 24 again.

FIG. 4 is a schematic plan view of the laser power measurement device 50 . An optical holder 52 is fixed to the slide plate 51 . A beam splitter 53 , a power meter 54 as a first sensor, and a photodetector 55 as a second sensor are attached to the optical holder 52 . The pulsed laser beam LB output from the laser oscillator 12 ( FIG. 2 ) is incident on the beam splitter 53 at an incident angle of 45°. The sliding plate 51 can move along the optical axis of the pulsed laser beam LB.

About 2% to 5% of the pulsed laser beam incident on the beam splitter 53 passes through the transmission beam splitter 53 and is incident on the light-receiving surface 54A of the power meter 54 . The incident angle to the light-receiving surface 54A is, for example, 45°. The remaining components in the pulsed laser beam LB incident on the beam splitter 53 are reflected by the beam splitter 53, and are incident on the beam shaping optical system 81 (FIG. 1). As the beam splitter 53, a partial reflection mirror, a polarization beam splitter, or the like can be used.

The power meter 54 measures the average power of the pulsed laser beam incident on the light-receiving surface 54A. A voltage signal corresponding to the measured value of the average power is input to the laser power source 60 . A part of the pulsed laser beam incident on the light receiving surface of the power meter 54 is scattered by the light surface 54A. Part of the scattered light is incident on the light receiving surface 55A of the photodetector 55 . The light-receiving surface 55A of the photodetector 55 is arranged at a position where the light that is regularly reflected by the light-receiving surface 54A of the power meter 54 is incident. Usually, the area of the light-receiving surface 55A of the photodetector 55 is smaller than the area of the light-receiving surface 54A of the power meter 54 .

As the photodetector 55, for example, an MCT (HgCdTe) sensor is used. MCT sensors are characterized by fast response, such as nanosecond-level response characteristics. Accordingly, the photodetector 55 can measure the pulse waveform and peak power of a laser pulse with a pulse width of the nanosecond level.

The photodetector 55 outputs a voltage signal corresponding to the power of the light incident on the light receiving surface 55A. The voltage signal is input to the laser power source 60 through the amplifier 59 .

Next, referring to FIGS. 5 to 6F , the excellent effects of the above-mentioned embodiment will be described. FIG. 5 is a schematic diagram of a laser power measuring apparatus based on a comparative example. A part of the component of the pulsed laser beam LB is reflected by the first beam splitter 53A, and is incident on the light-receiving surface 55A of the photodetector 55 . Part of the pulsed laser beam that has passed through the first beam splitter 53A passes through the second beam splitter 53B, and is incident on the light-receiving surface 54A of the power meter 54 . The pulsed laser beam reflected by the second beam splitter 53B is used for laser processing. An energy loss corresponding to the total energy of the pulsed laser beam reflected by the first beam splitter 53A and the pulsed laser beam transmitted through the second beam splitter 53B is generated.

In the comparative example shown in FIG. 5 , the two beam splitters, the first beam splitter 53A and the second beam splitter 53B, are arranged at different positions along the path of the pulsed laser beam LB. In contrast to this, one beam splitter 53 is used in this embodiment. In the present embodiment, by reducing the number of beam splitters compared to the comparative example, the path length of the pulsed laser beam LB can be suppressed from being increased, and as a result, space saving can be achieved.

In the comparative example shown in FIG. 5 , a total of two energy losses occur in the first beam splitter 53A and the second beam splitter 53B. In contrast to this, in the present embodiment, the energy loss is based on the beam splitter 53 only once. Therefore, in the present embodiment, the energy loss can be reduced as compared with the comparative example.

The optical axis of the pulsed laser beam is generated due to changes in the oscillation duty ratio of the pulsed laser beam, deterioration of the laser medium gas, deterioration of optical components in the laser oscillator 12 (FIG. 2, FIG. 3), contamination, etc. deviation or beam profile changes. Next, the excellent effects of the present embodiment when optical axis deviation or beam profile change occurs will be described.

FIGS. 6A to 6C are diagrams showing beam profiles of the pulsed laser beam incident on the photodetector 55 of the laser power measuring apparatus according to the comparative example shown in FIG. 5 . The horizontal axis represents the position within the beam spot, and the vertical axis represents the light intensity. The center of the beam spot corresponds to the position of the optical axis of the laser beam. When the optical axis adjustment is performed, the optical axis (the center of the beam spot) of the pulsed laser beam coincides with the center of the light-receiving surface 55A. The beam spot is larger than the light-receiving surface 55A.

In the example shown in FIG. 6A , the optical axis of the pulsed laser beam LB ( FIG. 5 ) is not deviated from the position of the optical axis after the optical axis adjustment. Therefore, the center of the beam spot (in the case of a Gaussian beam, the position where the light intensity is maximum) coincides with the center of the light-receiving surface 55A.

In the example shown in FIG. 6B , as indicated by the dotted line in FIG. 5 , the optical axis of the pulsed laser beam LB is deviated from the position of the optical axis after the optical axis adjustment, and the center of the beam spot is deviated from the center of the light-receiving surface 55A. Therefore, compared with the case of FIG. 6A , the integrated value of the laser power incident on the light-receiving surface 55A becomes smaller. In this way, even if there is no change in the peak power of the pulsed laser beam LB, if the optical axis is deviated, the voltage signal output from the photodetector 55 will drop.

In the example shown in FIG. 6C , the optical axis of the pulsed laser beam LB is not deviated, the center of the beam spot coincides with the center of the light-receiving surface 55A, but the beam profile is distorted. Therefore, the integrated value of the laser power incident on the light-receiving surface 55A varies from the integrated value at the time of FIG. 6A . In this way, even if there is no change in the peak power of the pulsed laser beam LB, if the beam profile is aliased, the voltage signal output from the photodetector 55 will also change.

Even if there is no change in the peak power, if the voltage signal output from the photodetector 55 changes, the laser power supply 60 (FIG. 1) determines that the peak power changes and controls the discharge voltage. Consequently, normal control of the discharge voltage cannot be performed, resulting in failure of the control. In addition, since the light-receiving surface 54A of the power meter 54 ( FIGS. 4 and 5 ) is wider than the light-receiving surface 55A of the photodetector 55 , such a problem is less likely to occur.

FIGS. 6D to 6F are beam profiles of the pulsed laser beam incident on the photodetector 55 of the laser power measuring device 50 according to the embodiment shown in FIGS. 1 to 4 .

In the example shown in FIG. 6D , the optical axis of the pulsed laser beam LB ( FIG. 4 ) is not deviated from the position of the optical axis after the optical axis adjustment, and the center of the beam spot coincides with the center of the light-receiving surface 55A. In the present embodiment, since the scattered light (diffuse light) scattered by the light receiving surface 54A ( FIG. 4 ) of the power meter 54 is incident on the light receiving surface 55A of the photodetector 55 , the light receiving surface 55A is smaller than the case of FIG. 6A . The beam profile at the position widens and approaches a flat shape.

In the example shown in FIG. 6E , the optical axis of the pulsed laser beam LB ( FIG. 4 ) is deviated from the position of the optical axis after the optical axis adjustment, and the center of the beam spot is deviated from the center of the light-receiving surface 55A. However, since the beam profile has a wide and nearly flat shape, the amount of reduction in the integral value of the laser power is small when the optical axis is not deviated ( FIG. 6D ).

In the example shown in FIG. 6F , the optical axis of the pulsed laser beam LB is not deviated, the center of the beam spot coincides with the center of the light-receiving surface 55A, but the beam profile is distorted. However, since the original beam profile is nearly flat, even if the beam profile is aliased, the amount of variation in the integrated value of the laser power incident on the light-receiving surface 55A is small.

In this way, in this embodiment, even if the optical axis of the pulsed laser beam LB is deviated or the beam profile is aliased, the voltage signal from the photodetector 55 has little variation. Therefore, when the optical axis of the pulsed laser beam LB is deviated or the beam profile is aliased, the control failure of the discharge voltage is less likely to occur.

In order to solve the above problem in the comparative example, the following method can also be considered: the pulsed laser beam reflected by the first beam splitter 53A is introduced into the integrating sphere, and the light detector 55 detects the diffusely reflected light in the integrating sphere. Light. In this method, since the integrating sphere must be rearranged, the size of the apparatus and the increase in cost are caused.

Next, referring to FIG. 7 , a laser power measuring apparatus based on another embodiment will be described. Hereinafter, the description of the configuration common to the laser power measuring apparatus based on the embodiments shown in FIGS. 1 to 4 is omitted.

FIG. 7 is a schematic plan view of the laser power measuring apparatus 50 according to the present embodiment. In the present embodiment, the condensing optical component 30 is arranged between the light-receiving surface 54A of the power meter 54 and the light-receiving surface 55A of the photodetector 55 . The condensing optical component 30 condenses the light scattered by the light-receiving surface 54A of the power meter 54 and makes it incident on the light-receiving surface 55A of the photodetector 55 .

A condenser cone is used as the condenser optics 30 . The condensing cone has an inner surface that constitutes a side surface of a truncated cone (hereinafter also referred to as a truncated cone surface). The entrance-side opening 31 provided at the position corresponding to the bottom surface of the truncated cone is larger than the exit-side opening 32 provided at the position corresponding to the upper surface of the truncated cone. The entrance-side opening 31 faces the light-receiving surface 54A of the power meter 54 , and the exit-side opening 32 faces the light-receiving surface 55A of the photodetector 55 . Light scattered by the light-receiving surface 54A of the power meter 54 and incident on the incident-side opening 31 of the condensing optical component 30 enters the light-receiving surface 55A of the photodetector 55 through the exit-side opening 32 .

Next, the excellent effects of this embodiment will be described. In this embodiment, the light scattered by the light-receiving surface 54A of the power meter 54 is condensed and incident on the light-receiving surface 55A of the photodetector 55 . Therefore, the power of the light incident on the light-receiving surface 55A of the photodetector 55 is increased compared to the embodiment shown in FIGS. 1 to 4 . In other words, the transmittance of the beam splitter 53 can be reduced without reducing the power of the light incident on the light receiving surface 55A of the photodetector 55 . By reducing the transmittance of the beam splitter 53, energy loss can be reduced.

In fact, the conditions other than the presence or absence of the condensing optical component 30 were set to be the same, and in the structure in which the condensing optical component 30 was arranged and the structure in which the condensing optical component 30 was not arranged, the measurement of the power of the pulsed laser beam by the photodetector 55 was performed. Evaluate the experiment. In the structure in which the condensing optical components 30 are arranged, the area of the voltage waveform corresponding to one pulse is approximately 3.3 times that in the structure in which the light-converging optical element 30 is not arranged. From this evaluation experiment, it was confirmed that the power of the light incident on the light-receiving surface 55A of the photodetector 55 increases when the condensing optical component 30 is arranged.

When a carbon dioxide laser is used as the laser oscillator 12 , the wavelength of the pulsed laser beam is about 10.6 μm, so even if the truncated cone of the condensing cone is formed by machining, it can function as a reflecting surface. Since it is not necessary to perform high-precision mirror finishing, it is possible to suppress an increase in cost due to the additional arrangement of the condensing cone.

Next, a modification of the above-described embodiment will be described. In the above-mentioned embodiment, the condensing cone is used as the condensing optical component 30, but other optical components that can condense the scattered light and enter a specific area can also be used. For example, a condenser lens, a concave mirror, or the like can be used. In addition, in the above-mentioned embodiment, the side surface of the condensing cone is formed by the side surface of a truncated cone, but it may be formed by the side surface of a polygonal frustum such as a quadrangular pyramid, or may be formed by a paraboloid. In addition, as the condensing optical component 30, an internal reflection type parabolic lens or the like can be used. Internal reflection type parabolic lens is an optical component that condenses the light incident from the incident end face to the outgoing end face after being reflected by the side surface of the paraboloid.

Next, referring to FIG. 8 , a laser power measuring apparatus based on another embodiment will be described. Hereinafter, the description of the configuration common to the laser power measuring apparatus based on the embodiment shown in FIGS. 1 to 4 and the embodiment shown in FIG. 7 is omitted.

FIG. 8 is a schematic plan view of the laser power measuring apparatus 50 according to the present embodiment. In the embodiment shown in FIG. 7 , the incident angle of the pulsed laser beam LB to the light-receiving surface 54A of the power meter 54 is 45°. On the other hand, in the present embodiment, the incident angle θi is 22.5° or less. The light-receiving surface 55A of the photodetector 55 is arranged at a position where the light that has undergone regular reflection by the light surface 54A is incident. That is, the angle θr formed by the vector from the incident point of the pulsed laser beam LB on the light-receiving surface 54A to the center point of the light-receiving surface 55A and the normal vector of the light-receiving surface 54A is equal to the incident angle θi.

The condensing optical component 30 is arranged so that the central axis of the conical surface of the condensing optical component 30 is aligned with the straight line from the incident point of the pulsed laser beam LB on the light-receiving surface 54A to the center point of the light-receiving surface 55A.

Next, the excellent effects of this embodiment will be described. In this embodiment, since the incident angle θi of the pulsed laser beam on the light-receiving surface 54A of the power meter 54 is 22.5° or less, compared with the case where the incident angle θi is 45°, the beam formed on the light-receiving surface 54A point gets smaller. If the beam spot is small, the amount of scattered light from the light-receiving surface 54A that is captured by the condensing optical part 30 is larger. Thereby, more energy of the pulsed laser beam LB can be condensed to the photodetector 55 . In other words, the transmittance of the beam splitter 53 can be reduced without reducing the power of the light incident on the light-receiving surface 55A of the photodetector 55 . By reducing the transmittance of the beam splitter 53, energy loss can be reduced.

The conditions other than the incident angle θi were the same, and the voltage signal output from the photodetector 55 was measured when the incident angle θi was 45° and 22.5°. As a result, when the incident angle θi is set to 22.5°, the output of the photodetector 55 is approximately 1.2 times higher than when the incident angle θi is 45°. As described above, by reducing the incident angle θi, the power of the light incident on the light-receiving surface 55A of the photodetector 55 can be increased. In order to obtain a sufficient effect of increasing the power of the light incident on the light-receiving surface 55A, the incident angle θi is preferably set to 22.5° or less.

Next, referring to FIGS. 9A to 9C , the preferred shape of the truncated conical surface of the condensing cone will be described.

FIGS. 9A and 9B are diagrams showing an example of a path of light that is scattered by the light surface 54A and is incident on the edge of the incident-side opening 31 of the condensing optical component 30 . In FIGS. 9A and 9B , the apex angle of the truncated cone of the light-condensing optical component 30 is different, and the apex angle of the truncated cone shown in FIG. 9B is larger than the apex angle of the truncated cone shown in FIG. 9A . Here, the apex angle of the truncated cone refers to the apex angle of the cone including the truncated cone with the truncated cone as the side surface.

As shown in FIG. 9A , light scattered by the light surface 54A and incident on the edge of the incident side opening 31 of the condensing optical component 30 is reflected several times by the truncated cone, and then output to the outside through the exit side opening 32 . As shown in FIG. 9B , if the apex angle of the truncated conical surface is increased, the light scattered on the light receiving surface 54A and incident on the edge of the incident-side opening 31 of the condensing optical component 30 may be repeatedly reflected by the truncated conical surface. And it returns to the incident side opening part 31 .

In fact, an evaluation experiment for measuring the voltage signal output from the photodetector 55 was performed using a plurality of condensing optical components 30 having different apex angles of the truncated cone. In the evaluation experiment, the positions of the entrance side opening 31 and the exit side opening 32 on the straight line connecting the centers of the two light receiving surfaces 54A and 55A were fixed, and the size of the entrance side opening 31 was changed.

FIG. 9C is a graph showing the relationship between the magnitude of the vertex angle of the truncated cone and the magnitude of the voltage signal output from the photodetector 55 . The horizontal axis represents the normalized value of the vertex angle of the truncated cone, and the vertical axis represents the normalized value of the magnitude of the voltage signal from the photodetector 55 . When the vertex angle is of a certain size, the voltage signal from the photodetector 55 exhibits a maximum value. The size of the vertex at this time is set to 1, and the vertex is normalized. In addition, the output from the photodetector 55 at this time is set to 1, and the output is normalized.

As the normalized vertex angle becomes larger from 1, the normalized output of the photodetector 55 decreases. This is because, as shown in FIG. 9B , a part of the light incident on the entrance-side opening 31 is not output through the exit-side opening 32 and has many components that return to the entrance-side opening 31 . Also, even if the normalized vertex angle becomes smaller from 1, the normalized output of the photodetector 55 decreases. This is because the amount of scattered light condensed by the condensing optical component 30 is reduced because the area of the incident-side opening 31 is reduced.

As shown in Fig. 9C, there is an optimum value in the apex angle of the frustum that maximizes the output of the photodetector 55. For example, the apex angle of the truncated conical surface of the condensing optical part 30 is preferably set so that the light scattered by the light-receiving surface 54A of the power meter 54 and incident on the edge of the incident-side opening of the condensing optical part passes through the exit-side opening The size of the external output to the external. It is also preferable to maximize the incident-side opening 31 within a range that satisfies this condition.

The above-mentioned embodiments are examples, and of course, the structures shown in different embodiments may be partially replaced or combined. The same functions and effects based on the same structure of the plurality of embodiments will not be described one by one for each embodiment. In addition, this invention is not limited to the above-mentioned embodiment. For example, it will be apparent to those skilled in the art that various modifications, improvements, combinations, etc. can be made.

11: Bench 12: Laser oscillator 15: Chamber 16: Optical Room 17: Blower room 18: Upper and lower dividers 18A, 18B: Opening 19: Bottom plate 20: Optical resonator 20A: Optical axis 21: Discharge electrode 22: Electrode box 23: Electrode support member 24: Discharge area 25: Resonator lens 26: Resonator base 27: Optical resonator support member 28: Translucent window 29: Blower 30: Condensing Optical Parts 31: Incident side opening 32: Exit side opening 40: Divider 41: 1st gas flow path 42: Second gas flow path 43: Heat Exchanger 45: Support part 50: Laser power measurement device 51: Sliding board 52: Optical holder 53: Beam Splitter 53A: 1st beam splitter 53B: 2nd beam splitter 54: Power meter (first sensor) 54A: light-receiving surface 55: Photodetector (second sensor) 55A: light-receiving surface 59: Amplifier 60: Laser power supply 61: Controls 62: Discharge voltage application device 80: Processing device 81: Beam shaping optics 82: stage 90: Processing object 100: Shared base

FIG. 1 is a schematic diagram of a laser processing apparatus equipped with the laser power measuring apparatus according to the present embodiment. [FIG. 2] is a cross-sectional view including the optical axis of the laser oscillator. FIG. 3 is a cross-sectional view perpendicular to the optical axis of the laser oscillator according to the embodiment. [ Fig. 4 ] It is a schematic plan view of a laser power measuring device. FIG. 5 is a schematic diagram of a laser power measurement device based on a comparative example. [FIG. 6A]~[FIG. 6C] are beam profiles showing the pulsed laser beam incident on the photodetector of the laser power measuring device based on the comparative example shown in FIG. 5, [FIG. 6D]~[FIG. 6F] ] represents the beam profile of the pulsed laser beam incident on the photodetector of the laser power measuring device based on the embodiment shown in FIGS. 1 to 4 . FIG. 7 is a schematic plan view of a laser power measuring device according to another embodiment. [ Fig. 8] Fig. 8 is a schematic plan view of a laser power measuring apparatus according to still another embodiment. [ Fig. 9A ] and [ Fig. 9B ] are diagrams showing an example of the path of light scattered on the light-receiving surface and incident on the edge of the incident-side opening of the condensing optical component, and [ Fig. 9C ] is a diagram showing the apex angle of the truncated conical surface The relationship between the magnitude of and the magnitude of the voltage signal output from the detector.

51: Sliding board

52: Optical holder

53: Beam Splitter

54: Power meter (first sensor)

54A: light-receiving surface

55: Photodetector (second sensor)

55A: light-receiving surface

59: Amplifier

60: Laser power supply

LB: pulsed laser beam

Claims (5)

A laser power measuring device is provided with: The first sensor has a light-receiving surface on which the laser beam is incident, and measures the average power of the laser beam incident on the light-receiving surface; and The second sensor is arranged at a position where scattered light from the light-receiving surface of the first sensor is incident, and measures the peak power of the incident laser beam. The laser power measuring device according to claim 1, further comprising: The light-condensing optical component is used for condensing the light scattered by the light-receiving surface of the first sensor and entering the second sensor. The laser power measuring device according to claim 2, wherein, The incident angle of the laser beam to the light-receiving surface of the first sensor is 22.5° or less, and the condensing optical component is arranged at a position where the light that is specularly reflected by the light-receiving surface of the first sensor is incident. The laser power measuring device according to claim 3, wherein, The condensing optical component is a condensing cone, the inner surface of the condensing cone constitutes the side surface of the truncated cone, and the incident side opening at the position corresponding to the bottom surface of the truncated cone faces the first sensor and corresponds to the upper surface of the truncated cone. The exit-side opening at the position faces the second sensor. The laser power measuring device according to claim 4, wherein, The apex angle of the inner surface of the condensing optical part is set so that the light scattered by the light-receiving surface of the first sensor and incident on the edge of the incident-side opening of the condensing optical part is output to the exit-side opening through the exit-side opening. external size.

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