JP2007038226A - Laser machining monitoring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser machining monitoring device capable of monitoring the condition of an optical system and the actual laser output state by a highly reliable in-line system in a laser machining head and at a machining point where laser beams are received from optical fibers and a workpiece is irradiated with the laser beams. <P>SOLUTION: Laser beams LB generated or oscillation-output by a laser beam oscillator 10a in a laser machine body 10 are transmitted through optical fibers 14 for laser beam transmission to a remote laser machining head 12, and condensed toward a machining point WP of a workpiece W from the laser machining head 12 to allow the workpiece to be irradiated therewith. A monitor device body 16 is connected to the laser machining head 12 via two optical fibers 20, 22 for monitoring to display and output monitoring information on the laser output state of the laser beams LB immediately before irradiation from the laser machining head 12 toward the machining point of the workpiece W, a state of an optical component on a laser beam transmission path, and the machining quality at the machining point WP. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a laser processing monitoring apparatus using an optical fiber.

  In recent years, high-power lasers have been widely used in the field of processing industries such as welding, cutting or surface treatment. In particular, laser welding is becoming more and more important because it enables high-precision and high-speed machining, low thermal strain on the workpiece, and high-level automation. Further, remote laser welding using an optical fiber is possible, and it is not uncommon for welding to be performed at a remote location, for example, 30 m to 50 m away from the laser oscillator. A general laser welding machine has a function to monitor the laser output of the laser light oscillated and output from the built-in laser oscillator. If there is an abnormality in the laser oscillator, the situation is detected immediately by monitoring the laser output. It can be done.

  However, in remote laser processing, the laser beam oscillated and output from the laser oscillator is irradiated to the workpiece at a remote location via an optical system such as an incident unit, an optical fiber, and a laser processing head. Even if the laser output at the processing point of the workpiece is abnormally lowered due to dirt, damage, or deterioration of some optical parts on the laser beam path, the main body cannot grasp it. For this reason, it is necessary to discover defects only after the inspection after processing (appearance inspection, destructive inspection, nondestructive inspection, etc.), and there is a problem in production management (such as frequent occurrence of defective products). Moreover, the maintenance method (checking, cleaning, repair, parts replacement, etc.) of each part regularly in a short cycle has to stop the production line frequently for maintenance work, and in terms of production efficiency There's a problem. Conventionally, the output state of the laser light emitted from the laser processing head is also monitored by measurement with a laser power meter. However, this method is also performed with laser processing stopped, and there is a disadvantage that productivity is lowered.

  The present invention has been made in view of the above-mentioned problems of the prior art, and in an optical fiber transmission system, the actual laser output state on the laser processing head side, the processing state, the state of the optical system, etc. are highly reliable. It is an object of the present invention to provide a laser processing monitoring device that improves the production control, quality control, and production efficiency of laser processing by monitoring in-line.

  In order to achieve the above object, a first laser processing monitoring device of the present invention transmits laser light oscillated and output from a laser oscillation section to a laser processing head through an optical fiber for laser transmission, and A laser processing monitoring device for irradiating a processing point of a workpiece with a laser beam from a laser emission port of a processing head, wherein the laser beam is emitted from a terminal surface of the optical fiber for laser transmission in the laser processing head A first monitoring optical fiber that receives a part of light at one end surface and transmits the light to a remote first photoelectric conversion unit, and the other end surface of the first monitoring optical fiber in the first photoelectric conversion unit A first photoelectric conversion element that receives the light emitted from the first photoelectric conversion element and converts the light into a first electric signal; and the first electric signal output from the first photoelectric conversion element. And a signal processing unit for outputting the monitoring information on the laser power of the laser beam just before it is irradiated to the machining point of the workpiece from the laser processing head.

  In the above configuration, the light intensity (laser output) immediately before the laser beam is emitted in the laser processing head is detected by the first monitoring optical fiber and the first photoelectric conversion element, and converted into the first electric signal. Since the signal processing unit performs the monitoring signal processing based on the first electric signal after conversion, the state of the laser optical system including the optical fiber for laser transmission can be accurately measured or monitored in-line. In addition, a monitoring optical fiber with very low temperature characteristics (temperature dependence) is attached to the laser processing head as an optical sensor, and a photoelectric conversion element having a relatively large temperature characteristic is located far from the laser processing head. Therefore, it is possible to accurately monitor the laser power state of the laser beam immediately before irradiation at the processing site without being affected by severe environmental temperature or temperature change around the laser processing head. Furthermore, since the optical transmission in the first monitoring optical fiber is not affected by ambient electromagnetic noise at all, it is not necessary to provide a special noise removal circuit in the signal processing unit, and high-precision monitoring can be performed with a simple configuration. Can be realized.

  The second laser processing monitoring device of the present invention transmits the laser beam oscillated and output from the laser oscillating unit to the laser processing head through the optical fiber for laser transmission, and the laser processing head processes the laser beam. A laser processing monitoring apparatus for irradiating a processing point of an object, wherein all or part of light reflected from the processing point of the workpiece into the laser emission port of the laser processing head is applied to one end surface. A second monitoring optical fiber that receives the light and transmits it to a remote second photoelectric conversion unit; and receives light emitted from the other end surface of the second monitoring optical fiber in the second photoelectric conversion unit. A second photoelectric conversion element for converting into an electric signal and a laser beam at a processing point of the workpiece based on the second electric signal output from the second photoelectric conversion element. And a signal processing unit for outputting a determination result by determining the state of over.

  In the above configuration, the light reflected from the processing point of the workpiece into the laser processing head is detected by the second monitoring optical fiber and the second photoelectric conversion element and converted into the second electrical signal, Since the signal processing unit performs monitoring signal processing based on the second electric signal, the laser power state and the processing state at the processing point can be accurately measured or monitored in-line. In addition, an optical fiber with a very small temperature characteristic (temperature dependence) is attached to the laser processing head as an optical sensor, and a photoelectric conversion element having a relatively large temperature characteristic is arranged on the side of the photoelectric conversion unit far from the laser processing head. Therefore, it is possible to accurately monitor the laser power state and the processing state of the laser light irradiated to the workpiece without being affected by the severe environmental temperature or temperature change around the laser processing head. Furthermore, since the optical transmission in the second monitoring optical fiber is not affected by ambient electromagnetic noise at all, it is not necessary to provide a special noise removal circuit in the signal processing unit, and highly accurate monitoring can be performed with a simple configuration. Can be realized.

  The third laser processing monitoring device of the present invention transmits the laser beam oscillated and output from the laser oscillation unit to the laser processing head through the optical fiber for laser transmission, and the laser processing head processes the laser beam. A laser processing monitoring apparatus for irradiating a processing point of an object, wherein a part of the laser beam emitted from the end surface of the optical fiber for laser transmission in the laser processing head is received at one end surface to remotely A first monitoring optical fiber that transmits to the first photoelectric conversion unit; and light emitted from the other end surface of the first monitoring optical fiber in the first photoelectric conversion unit to receive a first electric A first photoelectric conversion element for converting into a signal, and all or part of the light reflected from the processing point of the workpiece into the laser emission port of the laser processing head. And receiving light emitted from the other end surface of the second monitoring optical fiber in the second photoelectric conversion unit. And the second photoelectric conversion element for converting into the second electric signal, and the laser light passes based on the first and second electric signals output from the first and second photoelectric conversion elements, respectively. A signal processing unit that determines the state of the optical component and / or the state of the laser power at the processing point of the laser beam and outputs a determination result.

  In the above configuration, by having both the configurations of the first and second laser processing monitoring devices, the respective operational effects can be achieved simultaneously.

  According to a preferred aspect of the present invention, a first temperature control unit for maintaining the temperature of the first photoelectric conversion element at a set temperature is provided in the first photoelectric conversion unit, and the first monitoring light is provided. A first optical filter is provided between the emission end face of the fiber and the first photoelectric conversion element. Preferably, the first photoelectric conversion unit adjusts the gain of the first amplifier and the first contact electrically connected to the output terminal of the first photoelectric conversion element via the first amplifier. And an insulating first connector body that holds the first contact, the first amplifier, and the first volume, and that is integrally coupled to the end of the first monitoring optical fiber. Have

  Further, a second temperature control unit for keeping the temperature of the second photoelectric conversion element at a set temperature is provided in the second photoelectric conversion unit, and the emission end face of the second monitoring optical fiber and the second photoelectric conversion unit are provided. A second optical filter is provided between the conversion element. Preferably, the second photoelectric conversion unit adjusts the gain of the second amplifier and the second contact electrically connected to the output terminal of the second photoelectric conversion element via the second amplifier. And a second contact for holding the second contact, the second amplifier, and the second volume, and integrally coupling to the terminal end of the second monitoring optical fiber. And a main body.

  In the above configuration, the photoelectric conversion function and related functions are all contained in the photoelectric conversion unit attached to the end of the monitoring optical fiber, so that the laser processing head is prevented from becoming bulky, and monitoring is performed with an efficient and compact configuration. The reliability of accuracy can be further improved.

  Further, according to a preferred aspect, in the laser processing head, most of the laser light emitted from the end face of the optical fiber for laser transmission is reflected to the processing point side of the workpiece, and part of the light leaks. Is provided as a transmission mirror. Alternatively, a mirror that passes most of the laser light emitted from the end face of the optical fiber to the processing point side of the workpiece and reflects a part thereof in a predetermined direction may be provided. Usually, a protective glass is attached to the exit of the laser irradiation unit, and an optical lens for focusing the laser light emitted from the end face of the optical fiber for laser transmission on the processing point of the workpiece is provided in the laser irradiation unit.

  According to a preferred aspect, the first monitoring optical fiber, the second monitoring optical fiber, and the laser transmission optical fiber are attached to the surface opposite to the laser emission port of the laser processing head. According to such a configuration, since the cables can be concentrated above the head and aerial wiring or laid, the mounting or mounting of the processing head is easy, the space efficiency near the processing location and the usability are improved, and the processing head The maintenance of itself and the safety at the time of laser leakage are also improved.

  According to the laser processing monitoring apparatus of the present invention, with the configuration and operation as described above, the actual laser output state, processing state, optical system state, etc. on the laser processing head side in the optical fiber transmission system is highly reliable inline. Monitoring system can improve production control, quality control and production efficiency of laser processing.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 shows an overall configuration of a laser processing apparatus to which a laser processing monitoring apparatus according to an embodiment of the present invention can be applied. This laser processing apparatus has, as a basic configuration, a laser processing machine main body 10 including a laser oscillator 10a that oscillates and outputs laser light for laser processing (for example, pulsed laser light) LB, and laser processing disposed at a desired processing location. Controls the head 12, the optical fiber 14 that optically connects the laser processing machine main body 10 and the laser processing head 12, the monitor main body 16 that performs necessary signal processing and display output for monitoring, and the entire system sequence. Controller 18.

  In this laser processing apparatus, the laser beam LB generated or oscillated and output by the laser oscillator 10a in the laser processing machine main body 10 is transmitted to the remote laser processing head 12 through the optical fiber 14 and is transmitted from the laser processing head 12 to the workpiece. (Workpiece) Condensed and irradiated toward the processing point WP of W. For example, in the case of welding, at the processing point WP of the workpiece W, two members that are overlapped (or abutted) with each other are melt-bonded by the laser energy of the laser beam LB. The monitoring device main body 16 is connected to the laser processing head 12 via two optical fibers 20 and 22 for monitoring, and the laser light immediately before being irradiated from the laser processing head 12 toward the processing point WP of the workpiece W. Monitoring information relating to the laser output state of the LB, the state of the optical components on the laser transmission path, the processing quality at the processing point WP, and the like is displayed and output.

  The laser oscillator 10a has, for example, a laser oscillator of a solid laser such as a YAG laser, a fiber laser, or a disk laser, or a laser oscillator of a gas laser such as a carbon dioxide gas laser. In the laser processing machine main body 10, an incident unit (not shown) for condensing and incident the laser beam LB emitted from the laser oscillator 10 a onto one end surface of the optical fiber 14, or the laser beam LB immediately before entering the optical fiber 14. A laser output measuring unit (not shown) for measuring the laser output is also provided. The optical fiber 14 may be an arbitrary multimode optical fiber, for example.

  The laser processing head 12 has a hollow housing or head main body 24 made of, for example, aluminum, and an optical lens, a mirror, etc., which will be described later, are arranged at a predetermined position in the head main body 24. In the head main body 24, a laser emission port 26 is provided on the lower surface of the main body facing the processing point WP of the workpiece W, and the laser transmission optical fiber 14 and the monitoring optical fiber are provided on the main body upper surface opposite to the laser emission port 26. 20 and 22 are attached.

  FIG. 2 shows a specific configuration of the laser processing head 12 in this embodiment. A cylindrical portion 28 extending downward from the center of the lower surface of the head main body 24 is formed, and a protective glass 30 is attached to a laser emission port 26 located at the lower end of the cylindrical portion 28, and is focused near the inner depth of the protective glass 30. A lens 32 is arranged.

  A vent mirror 34 is disposed immediately above the focusing lens 32 at a substantially central position inside the head main body 20 with its reflecting surface 34a inclined downward at an angle of, for example, 45 °, and further directly above the light for detecting reflected light. The fiber 22 is attached to a connector or receptacle 36 with its light receiving surface 22a facing vertically downward. Between the vent mirror 34 and the light receiving surface 22a of the optical fiber 22, for example, a diffusion plate 38 made of ceramic is disposed.

  On the upper surface of the head main body 24, a position shifted laterally from the optical fiber 22 on the head central axis line, that is, a position offset laterally (right side in FIG. 2) from the optical axis passing through the vent mirror 34 and the focusing lens 32, A cylindrical optical fiber emitting portion 40 extends vertically upward. A connector or a receptacle 42 is provided at the upper end of the optical fiber (the upper portion 40 is detachably receiving the end portion of the optical fiber 14).

  A collimating lens 44 for making the laser beam LB emitted radially from the end surface 14 a of the optical fiber 14 into parallel light is disposed inside the optical fiber emitting unit 40, and a vent mirror is provided directly below the collimating lens 44. 46 is arranged with its reflecting surface 46a obliquely upward at an angle of 45 °, for example. Here, the reflecting surface 46 a of the vent mirror 46 is optically opposed to the reflecting surface 34 a of the vent mirror 34, and the laser light LB from the end surface 14 a of the optical fiber 14 moves horizontally from the vertical direction by the vent mirror 46. The light beam is incident on the bent mirror 32 after being bent at right angles to the direction, and is incident on the focusing lens 32 by bending the optical path perpendicularly downward from the horizontal direction. The focusing lens 32 focuses the laser beam LB on the processing point WP of the workpiece W.

On the upper surface of the head main body 24, the optical fiber 20 for detecting laser light is offset to a position opposite to the cylindrical optical fiber emitting portion 40 (left side in FIG. 2) along with the optical fiber 22 for detecting reflected light. Is attached to the connector or receptacle 48 with its light receiving surface 20a facing vertically downward. A vent mirror 50 is disposed directly below the light receiving surface 20a of the optical fiber 20 with its reflecting surface 50a inclined obliquely upward at an angle of 45 °, for example. Here, the reflecting surface 50 a of the vent mirror 50 is optically opposed to the reflecting surface 46 a of the vent mirror 46 via the vent mirror 34, and the laser light LB from the end surface 14 a of the optical fiber 14 is transmitted from the vent mirror 34. The light _MLB leaked to the rear (left side) of the vent mirror 34 upon reflection is incident on the vent mirror 50, and the vent mirror 50 bends the optical path perpendicularly upward from the horizontal direction to the light receiving surface 20a of the optical fiber 20. It is made to enter. A diffusing plate 52 made of, for example, ceramic is disposed between the vent mirror 34 and the vent mirror 50.

  In the laser processing head 12, as described above, the laser beam LB from the laser oscillator 10a on the laser processing machine main body 10 side is emitted radially from the end surface 14a of the optical fiber 14 within the optical fiber emitting section 40, The laser beam LB emitted radially passes through the collimator lens 44 and becomes parallel light. The laser beam LB that has become parallel light is bent from the vertical direction to the horizontal direction by the vent mirror 46, and then bent from the horizontal direction to the vertical downward direction by the vent mirror 34 in the center of the head 12. The light is focused and irradiated from the laser emission port 26 toward the processing point WP of the workpiece W through the lens 30.

In the vent mirror 34, a part of the laser beam LB incident from the vent mirror 46 side leaks backward in the horizontal direction. The leaked light _MLB enters the vent mirror 50 through the diffusion plate 52, bends the optical path vertically upward by the vent mirror 50, and enters the light receiving surface 20a of the optical fiber 20 positioned immediately above. Optical fiber 20 transmits the light M _LB incident on the light receiving surface 20a to the monitor main body 16.

On the other hand, there is also reflected light that enters the laser processing head 12 from the processing point WP of the workpiece W, and the reflected light R _LB that has passed through the protective glass 30, the optical lens 32, the vent mirror 34, and the diffusion plate 38 is the optical fiber 22. Is incident on the light receiving surface 22a. The optical fiber 22 also transmits the light R _LB incident on the light receiving surface 22 a to the monitor body 16.

  The optical fibers 20 and 22 are made of, for example, a multimode optical fiber, and photoelectric conversion units 54 and 56 are respectively attached to the other end portions (termination portions). These photoelectric conversion connectors 54 and 56 are monitoring devices. It is electrically connected to the signal processing circuit on the main body 16 side, for example, in the form of a connector. FIG. 3 shows a specific configuration example of the photoelectric conversion connectors 54 and 56. Hereinafter, although one photoelectric conversion connector 54 will be described, the other photoelectric conversion connector 56 has substantially the same configuration and function.

  In FIG. 3, a photoelectric conversion connector 54 has a housing-like connector main body 58A made of an insulator, for example, a resin, and in this connector main body 58A, a photoelectric conversion element 60A, an optical filter 62A, a temperature control unit 64A, a circuit board. 66A, amplifier 68A, volume 70A, etc. are accommodated and held. The terminal portion of the optical fiber 20 is also inserted into the connector main body 58A.

  The photoelectric conversion element 60 </ b> A is made of, for example, a photodiode, and is arranged with its light receiving surface facing the end surface 20 b of the optical fiber 20. The optical filter 62A provided between the emission end face 20b of the optical fiber 20 and the photoelectric conversion element 60A includes, for example, a transmission filter that selectively transmits the wavelength of the laser light LB, an ND filter for attenuation, and the like. The temperature control unit 64A includes a cylindrical heat conductive block 63A that houses the photoelectric conversion element 60A and the optical filter 62A, a heating element (for example, a resistance heating element) 65A attached to the heat conductive block 65A, and a temperature sensor ( For example, thermistor) 67A. A temperature control circuit (not shown) of the temperature control unit 64A uses the output signal (temperature detection signal) of the temperature sensor 67A as a feedback signal so as to keep the temperature of the photoelectric conversion element 60A and the optical filter 62A at a set temperature. Controls the power supplied to 65A. The amplifier 68A is a circuit that amplifies the output signal of the photoelectric conversion element 60A with a desired gain, and the volume 70A manually adjusts the gain of the amplifier 68A. The amplifier 68A and the volume 70A are provided for calibrating the accuracy of the optical measurement system from the light receiving surface 20a of the optical fiber 20 to the output terminal of the photoelectric conversion connector 54. The circuit board 66A is mounted with the photoelectric conversion element 60A, the amplifier 68A, the volume 70A, the temperature control circuit, and other related circuits.

  The photoelectric conversion connector 54 has a plug portion 72A to be inserted into the connector on the monitor device main body 16 side on the back of the connector main body 58A when viewed from the end face 20b side of the optical fiber 20, and a plurality of plugs 72A are included in the plug portion 72A. Contact pin 74A. A part of these contact pins 74A is electrically connected to the output terminal of the photoelectric conversion element 60A via the amplifier 68A, and the other part is electrically connected to the temperature control circuit of the temperature control unit 64A. ing.

In the photoelectric conversion connector 54, light (leakage light corresponding to the laser light LB) M _LB emitted from the end surface 20b of the optical fiber 20 enters the light receiving surface of the photoelectric conversion element 60A through the optical filter 62A. The photoelectric conversion element 60A outputs an electric signal (laser light intensity detection signal) S _L indicating the light intensity of the light _MLB incident on the light receiving surface. The laser light intensity detection signal S _L from the photoelectric conversion element 60A is amplified by the amplifier 68A and then sent from the contact pin 74A to a signal processing circuit in the monitor body 16 described later.

In the other photoelectric conversion connector 56, the light (reflected light) R _LB emitted from the end surface 22b of the optical fiber 22 enters the light receiving surface of the photoelectric conversion element 60B through the optical filter 62B. The photoelectric conversion element 60B outputs an electric signal (reflected light intensity detection signal) S _R indicating the light intensity of the light R _LB incident on the light receiving surface. The reflected light intensity detection signal S _R from the photoelectric conversion element 60B is sent to the signal processing circuit in the monitor main body 16 to be described later from the contact pins 74B after amplification by the amplifier 68B.

  In FIG. 1, a monitor device body 16 includes a panel input unit 16a including keys or buttons on a front panel and a panel display unit 16b such as a liquid crystal screen, and performs various arithmetic processes necessary for monitoring according to the present embodiment. Built-in electronic circuit. The electronic circuit in the monitor device main body 16 includes, for example, a microcomputer and functionally includes a control unit 80, a laser light measurement calculation unit 82, a reflected light measurement calculation unit 84, and comparison units 86 and 88 as shown in FIG. , A monitor section setting section 90, a calculation section setting section 92, and the like. The control unit 80 performs a man-machine interface with the user through the panel input unit 16a and the panel display unit 16b. In addition, every time the laser beam LB is oscillated and output from the laser welding machine body 10, the control unit 80 synchronizes timing signals. The controller 18 receives a laser processing condition or condition number from the controller 18 and gives a necessary control signal or data to each part in the unit.

3, the laser beam measurement computation unit 82, based on the laser beam intensity detection signal S _L that is input from the contact pins (output terminals) 74A of the photoelectric conversion connector 54 coupled to the end portion of the optical fiber 20, laser A light intensity measurement value P _L of the laser beam LB immediately after being emitted from the end face 14 a of the optical fiber 14 in the processing head 12 is obtained. In general, the laser beam LB for laser welding is oscillated and output as a pulsed laser beam having a substantially rectangular laser output waveform as shown in FIG. When such a pulse laser beam LB is passed through the optical fiber 14, the amplitude or light intensity (laser output) is attenuated during fiber transmission as shown in FIG. The substantially rectangular laser output waveform is generally maintained. The laser light measurement calculation unit 82 obtains a peak value or an average value of the input light intensity detection signal S _L and multiplies it by a predetermined coefficient to obtain a light intensity measurement value P _L immediately after the laser light LB is emitted from the fiber. The laser light intensity measurement value P _L obtained by the laser light measurement calculation unit 82 is given to the control unit 80 and also to both comparison units 86 and 88. The control unit 80 may display and output the laser beam intensity measurement value P _L from the laser beam measurement calculation unit 82 as it is on the panel display unit 16b.

The comparison unit 86 is given a comparison reference value AP _L and a determination reference value J from the control unit 80. Here, the comparison reference value AP _L corresponds to the laser output setting value of the laser beam LB given from the controller 18 or the laser output measurement value of the laser beam LB given from the laser output measuring unit of the welding machine body 10. . The comparison / determination unit 86 obtains the ratio or ratio (P _L / AP _L ) of the laser light intensity measurement value P _{L to} the comparison reference value AP _L and compares the ratio (P _L / AP _L ) with the determination reference value J. To do. The control unit 80 receives the comparison result from the comparison unit 86, and when the ratio (P _L / AP _L )> J, the laser beam LB immediately after being emitted from the end surface of the optical fiber 14 in the laser processing head 12. When the laser output exceeds the reference value, that is, it is determined to be normal, and the ratio (P _L / AP _L ) ≦ J, the laser output of the laser beam LB is lower than the reference value, that is, is abnormal. Is determined.

  Thus, when an abnormal drop in the laser output is detected through the optical fiber 20, the tolerance of any of the optical components on the laser transmission path from the laser oscillator 10 a of the laser oscillation source to the vent mirror 34 in the laser processing head 12 is allowed. This is the case when there is more dirt, damage, deterioration, etc. If there is an abnormality around the laser oscillator 10a, it is detected by monitoring by a laser output measuring unit in the laser processing machine body 10. If there is no abnormality on the main body 10 side, the bent mirrors 46 and 34 are usually hardly contaminated / damaged / deteriorated, so it is determined that there is a cause (mainly damage / deterioration) of the optical fiber 14. Can be estimated. The control unit 80 may display and output the determination result through the panel display unit 16a, and may issue an appropriate alarm or message when the abnormality determination result is output. Furthermore, the determination result can also be sent to the controller 18.

The reflected light measurement calculation unit 84 performs the laser welding based on the reflected light intensity detection signal S _R sent from the contact pin (output terminal) 74B of the photoelectric conversion connector 56 coupled to the terminal end of the optical fiber 22. obtaining a light intensity measurements P _R of the reflected light R _LB emitted from the processing point WP of the workpiece W to the processing head 12 side. In general, this type of reflected light R _LB is detected as a laser output waveform considerably deformed from a rectangle as shown in FIG. In this embodiment, a monitor interval setting unit 86 and a calculation interval setting unit 88 are provided, and the user can arbitrarily set and input a desired monitor interval T _M and calculation interval T _C through the panel input unit 16a. Yes.

For example, as shown in FIGS. 8 and 9, if the monitor interval T _M can be set to a period including only one (single shot) pulse laser beam as shown in FIGS. It is also possible to set a period including a plurality (multiple shots) of pulsed laser light. In the latter case (multiple shots), it is possible to evaluate pass / fail judgment for the entire pulse train (collective). The computation interval T _C is a second time point (t _c ) before the falling edge (t _d ) from the first time point (t _b ) after the desired time after the rising edge (t _a ) of the pulse laser beam. ) Can be set as _a section (t _{a to} t _b ). Actually, the reflected light R _LB from the workpiece W shows an unstable overshoot waveform due to the influence of the workpiece surface state at the time of rising of the pulse laser beam, and after it settles, the reflected light intensity corresponding to the original laser output Indicates. It reflected light measuring unit 84 calculates, in accordance with an instruction from the control unit 80 (or the user), in order to obtain the light intensity measurements P _R of the reflected light R _LB, a calculation interval T _C eg integral value E _R or the average value _PAV is calculated. The integral value E _R corresponds to the laser energy (joule) of the pulse laser beam. The average value P _AV may be an arithmetic average obtained by sampling the light intensity detection signal S _R at an appropriate period. Although not illustrated, it may be a light intensity measurements P _R with the maximum value or peak value in the calculation interval T _C. The monitoring and multiple shots of monitoring each pulse is basically only the length of the monitoring interval T _M to set the user is different, requires no special switching algorithm or hardware or software.

The reflected light intensity measurement value P _R obtained by the reflected light measurement calculation unit 84 is given to the control unit 80 and also to the comparison unit 88. Control unit 80 may be directly displayed and output on the display panel 16b the light intensity measurements P _R from the reflected light measurement computation unit 84. The comparison unit 88 is provided with the light intensity measurement value P _LB from the laser beam measurement calculation unit 82 as described above, and the control unit 80 receives the determination reference value D for normality / abnormality of the processing portion and the welding quality determination. A judgment reference value F and a required coefficient K are given. Here, the coefficient K is set according to the laser processing conditions (particularly the material of the workpiece W, etc.). The determination reference value D for processing quality determination corresponds to the laser output setting value of the laser beam LB given from the controller 18 or the laser output measurement value of the laser beam LB given from the laser output measuring unit of the laser processing machine body 10. may be those, it may be set as the upper limit F _H and the lower limit value F _L.

For processing unit normal / abnormal determination, comparison unit 88 obtains the ratio or proportion of the reflected light intensity measurement P _R with respect to the laser beam intensity measurements P _LB immediately after the optical fiber emission (P _R / P _LB), the The ratio (P _R / P _LB ) is compared with the criterion value D. The control unit 80 receives the comparison result from the comparison unit 88, and when the ratio (P _R / P _LB )> D, the laser output at the processing point WP of the laser beam LB exceeds the reference value or threshold value, that is, processing. Is determined to be normal (no abnormality), and when the ratio (P _R / P _LB ) ≦ D, the laser output of the laser beam LB at the processing point WP is lower than the reference value or threshold value, that is, processing It is determined that there is an abnormality in the part.

  As described above, when it is determined that there is an abnormality in the processing part, there is an abnormality in the state of the workpiece W (particularly the surface state), or the optical parts on the optical path in the laser processing head 12, that is, the vent mirrors 40 and 34, the focusing This is a case where either the lens 32 or the protective lens 30 has dirt, damage, deterioration, etc. exceeding the tolerance. In any case, it is a scene where the laser processing should be stopped once and the processing portion should be inspected.

When an abnormality on the workpiece W side cannot be assumed, it can be determined or estimated that there is a cause on the optical component side. Usually, the vent mirrors 40, 34 and the focusing lens 32 built in the unit 12 rarely have a cause (dirt, damage, deterioration, etc.), and the case where the protective lens 30 facing the workpiece W is dirty is the cause. It is almost. In general, the contamination of the protective lens 30 increases with time. Therefore, it is also possible to monitor how the ratio (P _R / P _LB ) decreases with time. The control unit 80 may display and output a determination result urging inspection or inspection through the panel display unit 16a, and may issue an appropriate alarm or message when outputting the determination result of abnormality. Further, the determination result may be sent to the controller 18.

For welding (processing) quality judgment, the comparator 88 compares the reflected light intensity measurement P _R and the determination reference value F (upper limit F _H and the lower limit value F _L). Control unit 80 receives the comparison result from the comparison unit 88 determines that F _L <P _R <laser output at the processing point WP of the laser beam LB when the F _H is within the normal range welding good, P _R When ≦ F _L or P _R ≧ F _H, the laser output at the processing point WP of the laser beam LB is outside the normal range, and it is determined that the welding is defective. The control unit 80 outputs the determination result about the quality of processing through the panel display unit 16 a or sends it to the controller 18. Furthermore, it is also possible to send a determination result or reflected light intensity measurements P _R for the laser output feedback control in the laser processing machine main body 10.

In the monitor device main body 16 described above, the ratio (P _R / P) between the laser light intensity measurement value P _LB and the reflected light intensity measurement value P _R immediately after emission of the optical fiber in the comparison unit 88 in order to determine whether the processing part is normal or abnormal. _LB ) was obtained and compared with the criterion value D. However, as another approach, none of the laser light intensity measurements P _LB and the reflected light intensity measurement P _R by utilizing a certain point in a certain relationship between the laser power state at the processing point WP of the laser beam LB, the laser beam it is also possible from both sides of the intensity measurements P _LB and the reflected light intensity measurement P _R to evaluate the laser power condition of the work point comprehensively or complex.

As described above, in the laser processing monitoring device of this embodiment, the optical fibers 20 and 22 are attached to the laser processing head 12 as optical sensors, and the laser processing head 12 immediately after being emitted from the end face 14a of the optical fiber 14 in the processing head 12 is used. The light intensity of the laser beam LB is measured on the monitor body 16 side through the optical fiber 20, and the light intensity of the light R _LB reflected from the processing point WP of the workpiece W to the laser processing head 12 is transmitted through the optical fiber 22. Te measured by the monitor main body 16 side, of the optical components through which a laser beam LB on the basis of the laser beam LB light intensity measurements P _LB and the light intensity measurement values P _R of the reflected light R _LB state, the workpiece W state, Optical measurement and pass / fail judgment can be made in-line for the laser output status, etc., and useful monitoring that is highly reliable for users in terms of production control or quality control. It is possible to provide the information. In addition, since abnormalities and failures are discovered and reported in a timely manner, it is possible to minimize the time required to stop the production line for maintenance such as replacement of protective glass.

  In particular, in this laser processing monitoring apparatus, photoelectric conversion connectors 54 and 56 are attached to the terminal portions of the monitoring optical fibers 20 and 22, and the emission end faces 20 b and 20 b of the optical fibers 20 and 22 are installed in the photoelectric conversion connectors 54 and 56. Photoelectric conversion elements 60A and 60B are optically coupled to 22b. Thus, the optical fibers 20 and 22 having very small temperature characteristics (temperature dependence) are attached to the laser processing head 12, and the photoelectric conversion elements 60 </ b> A and 60 </ b> B having relatively large temperature characteristics are separated from the laser processing head 12. Since it is arranged on the monitor main body 16 side, the laser power state of the laser beam LB at the processing site, the processing state of the processing point WP, etc. are not affected by severe environmental temperature or temperature change around the laser processing head 12. It can be monitored accurately.

  In general, since the monitor main body 16 is disposed on the laser processing machine main body 10 side, the length of the optical fibers 20 and 22 is not limited to 10 meters to several tens of meters. Is not affected by ambient electromagnetic noise. As a result, it is not necessary to provide a special noise removal circuit in the signal processing circuit on the monitor body 16 side, and highly accurate monitoring can be realized with a simple configuration.

  Further, temperature control units 64A and 64B for controlling the temperature of the photoelectric conversion elements 60A and 60B and the optical filters 62A and 62B in the photoelectric conversion connectors 54 and 56, amplifiers 68A and 68B for calibration of measurement accuracy, and volumes 70A and 70B. Etc., and the reliability of the monitoring accuracy can be further improved efficiently without making the laser processing head 12 bulky.

  Furthermore, in the laser processing head 12 of this embodiment, the laser transmission optical fiber 14 and the monitoring optical fibers 20 and 22 are connected to or attached to the upper surface of the laser processing head 12, so that all the cables are connected above the head. It can be aggregated into aerial wiring or laid. This simplifies the mounting or mounting of the machining head 12 on a head support unit or robot arm (not shown), improves the space efficiency near the machining location and ease of use, and improves the maintainability of the machining head 12 itself. . Further, even if the attachment ports of the optical fibers 20 and 22 are opened for some reason and the laser light is emitted from the processing head 12 to the outside, it leaks upward rather than to the side of the processing head 12. There is no risk of irradiation, and it is excellent in terms of safety.

  Next, another embodiment of the present invention will be described with reference to FIGS.

  FIG. 10 shows the overall configuration of the laser processing apparatus according to the second embodiment. This laser processing apparatus is mainly suitable for use in welding copper or gold, and a YAG fundamental pulse laser beam having a fundamental wavelength (1064 nm) and a harmonic, for example, a second harmonic (532 nm) YAG harmonic pulse laser. This is a laser processing apparatus that irradiates the processing point WP of the workpiece W with light superimposed thereon. The main part different from the first embodiment described above is provided with two YAG pulse laser oscillators 96 and 98 for oscillating and outputting the YAG fundamental laser beam LA and the YAG harmonic laser beam SHG, respectively, in the laser processing machine body 94. And an optical system that superimposes the YAG fundamental laser beam LA and the YAG harmonic laser beam SHG in the laser processing head 100 is incorporated.

  Both YAG pulse laser oscillators 96 and 98 and the laser processing head 100 are optically connected by optical fibers 102 and 104 for laser transmission, respectively. The laser processing head 100 has a hollow housing or head main body 106 made of, for example, aluminum, and an optical lens, a mirror, etc., which will be described later, are arranged at a predetermined position in the head main body 106. In the head main body 106, a laser emission port 108 is provided on the lower surface of the main body facing the processing point WP of the workpiece W. On the upper surface of the main body opposite to the laser emission port 108, laser processing optical fibers 102 and 104 and Optical fibers 114, 116, and 118 for monitoring are attached.

  11 to 13 show a specific configuration of the laser processing head 100. FIG. 11 is a top view, FIG. 12 is a longitudinal sectional view taken along line XX of FIG. 11, and FIG. 13 is a longitudinal sectional view taken along line YY of FIG.

  As shown in FIGS. 12 and 13, a cylindrical portion 120 extending downward from the central portion of the lower surface of the head main body 106 is formed, and a protective glass 122 is attached to the lower end portion of the cylindrical portion 120, that is, the laser emission port 108. A converging lens 124 is disposed in the vicinity of the inner side of the glass 122.

A YAG fundamental wave system bent mirror 126 is disposed directly above the focusing lens 124 at a substantially central position inside the head body 106 with its reflecting surface 126a inclined downward in the X direction at an angle of 45 °, for example (FIG. 12). The YAG harmonic system bent mirror 128 is disposed immediately above the reflecting surface 128a at an angle of 45 °, for example, obliquely downward in the Y direction (FIG. 13). A fiber 118 is attached to the connector or receptacle 130 with its light receiving surface 118a facing vertically downward (FIGS. 12 and 13). A diffusion plate 132 is disposed between the vent mirror 128 and the light receiving surface 118 a of the optical fiber 118.
As shown in FIG. 12, on the upper surface of the head main body 106, a cylindrical optical fiber emitting portion 134 extends vertically upward at a position offset in the X direction from the optical fiber 118 on the head central axis. A connector or receptacle 136 that detachably receives the terminal end of the optical fiber 102 is provided at the upper end of the optical fiber emitting portion 134.

  A collimating lens 138 for making the YAG fundamental wave laser beam LA emitted radially from the end surface 102 a of the optical fiber 102 into parallel light is disposed inside the optical fiber emitting section 134, and directly below the collimating lens 138. Further, the bent mirror 140 is disposed with its reflecting surface 140a obliquely upward at an angle of 45 ° in the −X direction, for example. Here, the reflecting surface 140a of the bent mirror 140 is optically opposed to the reflecting surface 126a of the bent mirror 126, and the YAG fundamental pulse laser beam LA from the end surface 102a of the optical fiber 102 passes through the optical path by the bent mirror 140. The light beam is bent at a right angle from the vertical direction to the horizontal direction (−X direction) and then incident on the vent mirror 126. It is like that. The focusing lens 124 focuses the YAG fundamental wave pulse laser beam LA on the processing point WP of the workpiece W.

On the upper surface of the head main body 106, the light for detecting the YAG fundamental wave laser light is offset from the optical fiber 118 for detecting reflected light to the position opposite to the YAG fundamental wave system optical fiber attachment portion 134 (-X direction). A fiber 114 is attached to the receptacle 145 with its light receiving surface 114a facing vertically downward. A vent mirror 142 is disposed directly below the light receiving surface 114a of the optical fiber 114 with the reflecting surface 142a inclined obliquely upward at an angle of 45 ° in the X direction, for example. Here, the reflecting surface 142a of the vent mirror 142 is optically opposed to the reflecting surface 140a of the vent mirror 140 via the vent mirror 126, and the YAG fundamental wave laser beam from the end surface 102a of the laser transmission optical fiber 102 is used. When LA is reflected vertically downward (on the focusing lens 124 side) by the bent mirror 140, the light _MLA leaked to the rear (−X direction) of the bent mirror 126 is incident on the bent mirror 142, and the optical path is horizontal by the bent mirror 142. The light is bent perpendicularly upward from the direction and enters the light receiving surface 114 a of the monitoring optical fiber 114. A diffusion plate 144 is disposed between the vent mirror 126 and the vent mirror 142.

  Further, as shown in FIG. 13, a cylindrical optical fiber emitting portion 146 extends vertically upward on the upper surface of the head main body 106 at a position offset in the Y direction from the monitoring optical fiber 118 on the head central axis. ing. At the upper end of the optical fiber emitting portion 146, a connector or receptacle 148 that detachably receives the terminal end of the laser transmission optical fiber 104 is provided.

  A collimating lens 150 for making the YAG harmonic pulse laser beam SHG emitted radially from the end face 104 a of the optical fiber 104 into parallel light is disposed inside the optical fiber emitting portion 146. Bent mirror 152 is arranged directly below the reflecting surface 152a obliquely upward at an angle of 45 ° in the Y direction, for example. Here, the reflecting surface 152 a of the bent mirror 152 is optically opposed to the reflecting surface 128 a of the bent mirror 128, and the YAG harmonic pulse laser beam SHG from the terminal surface 104 a of the optical fiber 104 passes through the optical path by the vent mirror 152. The light beam is bent at a right angle from the vertical direction to the horizontal direction (−Y direction) and then incident on the vent mirror 128, and the light path is bent at a right angle from the horizontal direction (−Y direction) to the vertical direction by the vent mirror 128 and passes through the vent mirror 126. The light enters the focusing lens 124. The focusing lens 124 focuses the YAG harmonic pulse laser beam SHG on the processing point WP of the workpiece W.

In FIG. 13, on the upper surface of the head main body 76, the YAG harmonic laser is offset from the optical fiber probe 118 for detecting reflected light to the position opposite to the YAG harmonic optical fiber mounting portion 146 (−Y direction). An optical fiber 116 for light detection is attached to the receptacle 155 with its light receiving surface 116a facing vertically downward. A vent mirror 154 is disposed directly below the light receiving surface 116a of the optical fiber 116 with the reflecting surface 154a facing obliquely upward at an angle of 45 ° in the Y direction, for example. Here, the reflecting surface 154a of the vent mirror 154 is optically opposed to the reflecting surface 152a of the vent mirror 152 via the vent mirror 128, and the YAG harmonic laser beam from the end surface 104a of the optical fiber 104 for laser transmission. When SHG is reflected vertically downward (on the converging lens 124 side) by the vent mirror 128, the light M _SHG leaked to the rear (−Y direction) of the vent mirror 128 is incident on the vent mirror 154, and the optical path is horizontal by the vent mirror 154. The light is incident on the light receiving surface 116a of the monitoring optical fiber 116 by bending it vertically upward from the direction (−Y direction). A diffusion plate 156 is disposed between the vent mirror 128 and the vent mirror 154.

In FIG. 10, monitoring optical fibers 114, 116, and 118 are made of, for example, multimode optical fibers, and photoelectric conversion connector units 158, 160, and 162 are attached to the other end portions (termination portions) thereof. The photoelectric conversion connectors 158, 160, 162 are electrically connected to a connector (not shown) on the monitor device body 16 side. Each photoelectric conversion connector 158, 160, 162 has substantially the same configuration and function as the photoelectric conversion connectors 54, 56 (FIG. 3) in the first embodiment, and the optical fiber 114, from the laser processing head 100, 116, 118, an electrical signal representing the light intensity of the light M _LA , M _SHG , R _LA transmitted, that is, the YAG fundamental laser light intensity detection signal S _LA , the YAG harmonic laser light intensity detection signal S _SHG , and the reflected light intensity. Each detection signal S _{R ′} is output.

The monitor device main body 16 is based on the YAG fundamental wave laser beam intensity detection signal S _LA , the YAG harmonic laser beam intensity detection signal S _SHG , and the reflected beam intensity detection signal S _{R ′} given from the photoelectric conversion connectors 158, 160, 162. Optical measurement and pass / fail judgment are performed in-line with respect to the state of the optical component through which the YAG fundamental wave laser beam LA and the YAG harmonic laser beam SHG pass, the state of the workpiece W, the laser output state, and the like.

  Also in this embodiment, the same effect as the first embodiment described above can be obtained. In particular, as the number of optical fibers 102 and 104 for laser processing and optical fibers 114, 116, and 118 for monitoring is large, monitoring accuracy / reliability / efficiency, simplicity of apparatus configuration, space efficiency / useability / Greater advantages in terms of maintainability and safety can be achieved.

  In the above embodiment, the laser transmission optical fiber 14 (102, 104) and the monitoring optical fibers 20, 22 (114, 116, 118) are all attached to the upper surface of the laser processing head 12 (100). For example, a configuration in which part or all of the laser beam is attached to the side surface of the laser processing head 12 (100) is also possible. Although not shown, the end face of the optical fiber is attached to a position facing the laser emission port or the protective lens in the laser processing head, and the laser light emitted from the end face of the optical fiber is straightened straight without going through the vent mirror. It is also possible to emit the light out of the protective lens. In that case, a mirror having a very low reflectance may be disposed in the middle, and the light reflected by the mirror may be guided to the light receiving surface of the monitoring optical fiber. The present invention is not limited to laser welding as in the above embodiment, but can be applied to any laser processing using an optical fiber.

It is a figure which shows the whole structure of the laser processing apparatus in one Embodiment of this invention. It is a longitudinal cross-sectional view which shows the specific structure of the laser processing head in embodiment. It is a longitudinal cross-sectional view which shows the specific structure of the photoelectric conversion connector in embodiment. It is a block diagram which shows the functional structure of the signal processing part in the monitor apparatus main body in embodiment. It is a wave form diagram which shows the waveform of the light in each part of the laser processing apparatus of embodiment. It is a figure which shows the monitoring area with respect to a single pulse laser beam, a calculation area, and the light intensity measurement calculation method (an example) in embodiment. It is a figure which shows the monitoring area with respect to a single pulse laser beam, a calculation area, and the light intensity measurement calculation method (an example) in embodiment. It is a figure which shows the monitoring section with respect to a series (a plurality of shots) pulsed laser beam, a calculation section, and the light intensity measurement calculation method (an example) in the embodiment. It is a figure which shows the monitoring section with respect to a series (a plurality of shots) pulsed laser beam, a calculation section, and the light intensity measurement calculation method (an example) in the embodiment. It is a figure which shows the whole structure of the laser processing apparatus in another embodiment. It is a top view which shows the structure of the ray processing head in another embodiment. It is a longitudinal cross-sectional view about the XX line of FIG. It is a longitudinal cross-sectional view about the YY line of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Laser processing machine main body 10a Laser oscillator 12 Laser processing head 14 Optical fiber for laser transmission 16 Monitor apparatus main body 18 Controller 20, 22 Monitoring optical fiber 30 Protective glass 32 Condensing lens 34, 46, 50 Vent mirror 44 Collimator lens 54, 56 Photoelectric conversion connector 58A, 58B Connector main body 60A, 60B Photoelectric conversion element 62A, 62B Optical filter 64A, 64B Temperature control unit 68A, 68B Amplifier 70A, 70B Volume 74A, 74B Contact pin 94 Laser processing machine main body 100 Laser processing head 102, 104 Optical fiber for laser transmission 114, 116, 118 Optical fiber for monitoring 158, 160, 162 Photoelectric connector

Claims (18)

A laser beam that is oscillated and output from a laser oscillation unit is transmitted to a laser processing head through an optical fiber for laser transmission, and the laser beam is irradiated to a processing point of a workpiece from a laser emission port of the laser processing head A monitoring device for processing,
A first monitoring optical fiber that receives a part of the laser light emitted from the end face of the laser transmission optical fiber in the laser processing head at one end face and transmits it to a remote first photoelectric conversion unit. When,
A first photoelectric conversion element that receives light emitted from the other end face of the first monitoring optical fiber in the first photoelectric conversion unit and converts the light into a first electrical signal;
Based on the first electric signal output from the first photoelectric conversion element, monitoring information related to the laser power of the laser beam immediately before being applied to the processing point of the workpiece is output from the laser processing head. And a laser processing monitoring device. Laser processing monitoring device for transmitting laser light oscillated and output from a laser oscillating section to a laser processing head through an optical fiber for laser transmission, and irradiating a processing point of a workpiece with the laser light from the laser processing head Because
A second part that receives all or part of light reflected from the processing point of the workpiece into the laser emission port of the laser processing head at one end surface and transmits the received light to a remote second photoelectric conversion unit. Optical fiber for monitoring,
A second photoelectric conversion element that receives light emitted from the other end face of the second monitoring optical fiber in the second photoelectric conversion unit and converts it into an electrical signal;
A laser processing unit including: a signal processing unit that determines a laser power state at a processing point of the workpiece based on the second electric signal output from the second photoelectric conversion element and outputs a determination result; Monitoring device. Laser processing monitoring device for transmitting laser light oscillated and output from a laser oscillating section to a laser processing head through an optical fiber for laser transmission, and irradiating a processing point of a workpiece with the laser light from the laser processing head Because
A first monitoring optical fiber that receives a part of the laser light emitted from the end face of the laser transmission optical fiber in the laser processing head at one end face and transmits it to a remote first photoelectric conversion unit. When,
A first photoelectric conversion element that receives light emitted from the other end face of the first monitoring optical fiber in the first photoelectric conversion unit and converts the light into a first electrical signal;
A second part that receives all or part of light reflected from the processing point of the workpiece into the laser emission port of the laser processing head at one end surface and transmits the received light to a remote second photoelectric conversion unit. Optical fiber for monitoring,
A second photoelectric conversion element that receives light emitted from the other end face of the second monitoring optical fiber in the second photoelectric conversion unit and converts the light into a second electric signal;
Based on the first and second electrical signals respectively output from the first and second photoelectric conversion elements, the state of the optical component through which the laser beam passes and / or the laser power at the processing point of the laser beam A laser processing monitoring device comprising: a signal processing unit that determines a state and outputs a determination result.   4. The laser processing monitoring apparatus according to claim 1, wherein a first temperature control unit is provided in the first photoelectric conversion unit to keep the temperature of the first photoelectric conversion element at a set temperature. 5.   5. The laser processing monitoring apparatus according to claim 1, wherein a first optical filter is provided between an emission end face of the first monitoring optical fiber and the first photoelectric conversion element. 6. The first photoelectric conversion unit is
A first contact electrically connected to an output terminal of the first photoelectric conversion element via a first amplifier;
A first volume for adjusting the gain of the first amplifier;
An insulating first connector body that holds the first contact, the first amplifier, and the first volume, and that is integrally coupled to a terminal portion of the first monitoring optical fiber. Item 6. The laser processing monitoring device according to any one of Items 1 to 5.   The laser processing monitoring apparatus according to any one of claims 2 to 6, wherein a second temperature control unit is provided in the second photoelectric conversion unit to keep the temperature of the second photoelectric conversion element at a set temperature.   The laser processing monitoring apparatus according to any one of claims 2 to 7, wherein a second optical filter is provided between an emission end face of the second monitoring optical fiber and the second photoelectric conversion element. The second photoelectric conversion unit is
A second contact electrically connected to the output terminal of the second photoelectric conversion element via a second amplifier;
A second volume for adjusting the gain of the second amplifier;
An insulating second connector main body that holds the second contact, the second amplifier, and the second volume, and that is integrally coupled to a terminal end of the second monitoring optical fiber. Item 9. The laser processing monitoring device according to any one of Items 2 to 8.   Provided in the laser processing head is a mirror that reflects most of the laser light emitted from the end face of the laser transmission optical fiber to the processing point side of the workpiece and transmits a part thereof as leakage light. The laser processing monitoring apparatus according to any one of claims 1 to 9.   In the laser processing head, there is provided a mirror that passes most of the laser light emitted from the end surface of the laser transmission optical fiber to the processing point side of the workpiece and reflects a part thereof in a predetermined direction. The laser processing monitoring apparatus according to any one of claims 1 to 9.   The laser processing monitoring apparatus according to claim 10 or 11, wherein a light receiving end face of the first monitoring optical fiber is disposed optically opposite to a terminal face of the optical fiber via the mirror.   The laser processing monitoring apparatus according to any one of claims 1 to 12, wherein the first monitoring optical fiber is attached to a surface of the laser processing head opposite to the laser emission port.   14. The optical lens for focusing the laser beam emitted from the end face of the laser transmission optical fiber on a processing point of the workpiece is provided in the laser processing head. The laser processing monitoring device described.   The laser processing monitoring apparatus according to claim 14, wherein the second monitoring optical fiber receives light that has passed through the optical lens from a processing point of the workpiece on one end surface.   The laser processing monitoring device according to any one of claims 1 to 15, wherein the second monitoring optical fiber is attached to a surface of the laser processing head opposite to the laser emission port.   The laser processing monitoring device according to claim 1, wherein the laser transmission optical fiber is attached to a surface of the laser processing head opposite to the laser emission port. The laser processing monitoring apparatus according to any one of claims 1 to 17, wherein a protective glass is attached to a laser emission port of the laser processing head.

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