JPH11320159A - Method and device for laser welding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable combination with a robot with low positioning accuracy, and adjust the position by a simple method so as to carry out laser welding. SOLUTION: A detecting laser from a laser diode 510 is reflected by a polarized prism 512 and radiated at the position separated by L2 from a center axis O of a work 1 via a lens 513 and the like. Then, the laser is reflected by the work 1 and incident on a photo diode 511. An optical axis of a processing laser light from an optical fiber 4 is set at the position separated by L1 from the center axis O of the work 1 in the route via a lens 520 and the like. A motor 55 inside a processing head is rotated for rotating wedge substrates 515, 521 and parallel flat substrates 516, 522. Furthermore, the irradiation position of the detecting laser and the optical axis of the processing laser in the work 1 are revolved around the center axis O as a center for detecting the butt face by the reflection light of the detecting laser. When the optical axis of the processing laser is positioned at the butt face, the processing laser is radiated to the work 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser welding method and a laser welding apparatus in which a laser beam output from a laser oscillator is transmitted through an optical fiber or the like, and butt welding is performed by a laser while positioning with a robot or the like. .

[0002]

2. Description of the Related Art As processing using pulsed laser light, processing methods such as cutting, drilling, welding, and the like are used in manufacturing processes in various fields such as machines, electronics, and semiconductor devices. An example in which the configuration of a conventional pulse laser welding apparatus is combined with a robot will be described with reference to FIGS.

As shown in FIG. 8, a conventional pulse laser welding apparatus includes a laser oscillator 3 comprising a laser head 31 and a laser power source 32,
Optical fiber 4 for transmitting the laser beam output from
And a processing head 5 for condensing a laser beam emitted from the optical fiber 4.

[0004] The pulse laser welding apparatus further includes a processing head 5, which is relatively moved by a robot 2 with respect to a workpiece 1 which is a workpiece. The laser power supply 32 is connected to the laser controller 3.
20, a stabilized power supply 321, a capacitor unit 322,
A switch unit 323.

In accordance with the voltage value instructed by the laser controller 320, the supplied AC voltage is
1, and the converted DC voltage is supplied to the capacitor unit 322. Then, the capacitor unit 32
2 is supplied to the switch unit 323, and discharged to the excitation lamp 310 of the laser head 31 based on the opening / closing timing of the switch unit 323.

The opening and closing of the switch section 323 is performed in accordance with a trigger signal instructing a pulse width and a pulse frequency from the laser controller 320. As described above, a pulsed laser beam is emitted from the laser head 31 and is applied to the work 1 via the optical fiber 4 and the processing head 5.

Next, a case where the above-described pulse laser processing apparatus and the robot 2 are combined to perform, for example, butt welding of a thin plate will be described. FIG. 9A shows an example in which straight line butt welding is performed, and FIG. 9B shows an example in which curved butt welding is performed. In the case of FIG. 9A, the coordinates of the processing start point A and the end point E are input to the robot 2 and the like, the processing head 5 is moved by linear interpolation between the points A and E, and a laser is irradiated during that time. Butt welding.

Also, in the case of FIG.
, An end point E, and arbitrary points B and C between them are set, and laser welding is performed by moving the processing head 5 between the points by linear or circular interpolation. In this case, since the robot 2 performs an in-position check at the start point, the end point, and the intermediate point, the robot 2 falls within a certain position accuracy range. A position error larger than the points A to E occurs. In particular, in the case of an articulated robot, since a straight line as shown in FIG. 9A also moves by a combination of each axis, a larger position error occurs than an orthogonal robot.

On the other hand, laser welding generally has a narrow bead width and features deep penetration welding.
If the laser irradiation position is displaced from the butt surface in the butt welding, problems such as insufficient penetration and a predetermined strength cannot be obtained.

When the laser welding apparatus is used in combination with the robot as described above, there is no problem particularly at the start point and the end point, but when the laser irradiation is displaced along the path, causing a problem such as insufficient strength. There is.

For this reason, various methods have been adopted as described below in order to improve the accuracy of the irradiation position. (1) A method of monitoring a phenomenon (for example, plasma emission) correlated with the irradiation position during laser processing and controlling the irradiation position based on this phenomenon (Japanese Patent Publication Nos. 59-33077 and 59-218291). Gazette). (2) A method of detecting a processing position using light or the like prior to a laser processing position and correcting the processing position based on the detected value (Japanese Patent Application Laid-Open No. 61-123494, Japanese Patent Publication No. 88150, JP-A-63-154283, JP-A-3-981079, and the like using a light-section method.

[0012]

However, the above-described method of correcting the processing position has the following problems. (1) When a phenomenon during laser processing is used, the position is corrected after the phenomenon is detected, that is, after the result after the processing is fed back, so that the correction is delayed. (2) Since the phenomenon itself that occurs during machining is caused by factors other than the machining position, it is difficult to distinguish and detect the phenomenon caused by the machining position and the phenomenon caused by other factors. (3) It is conceivable to accurately detect the processing position during or immediately before the processing by some processing position detecting means. The processing position may not be included, and at this time, the processing position cannot be detected. (4) It is conceivable to add a correction value to the servo control of the robot or the like, but it is necessary to change the original control method of the robot itself, and a large change is required, which is not a simple method. (5) It is conceivable to adopt a method of detecting and correcting a processing position by a method involving image processing such as a light section method. In this method, however, the calculation time for calculating the detection position is reduced. Since it becomes longer, the processing speed becomes slower.

An object of the present invention is to detect a change in the surface of a workpiece at a high speed with respect to a processing position error of a robot or the like combined for laser welding, and to combine with a robot having a low positioning accuracy. An object of the present invention is to realize a laser welding apparatus and a laser welding method capable of performing laser welding while performing position correction based on the above detection by simple means that does not change a control unit such as a robot.

[0014]

In order to achieve the above object, the present invention is configured as follows. (1) In a laser welding method of oscillating a pulsed processing laser beam and irradiating the processing laser beam onto the workpiece to weld the workpiece, a change in the surface of the workpiece is detected. The detection light is generated, and the optical axes of the detection light and the processing laser light are revolved coaxially on the surface of the workpiece, and the reflected light of the detection light from the workpiece is detected. The processing position of the object is detected, and the detected position is irradiated with the processing laser to process the object.

(2) A laser welding apparatus comprising: a laser oscillator for oscillating a pulsed laser beam for processing; and a processing optical system for guiding the processing laser beam to a processing position of a workpiece. A detection light source that generates detection light for detecting a change in the surface of the workpiece, and detection means that detects reflected light of the detection light from the workpiece and generates a detection signal corresponding to the detected light. , Based on the detection signal,
Control means for controlling the oscillation of the pulsed laser light so that a predetermined processing position of the workpiece is irradiated with the processing laser light; and the detection light and the processing laser light on the surface of the workpiece. And a rotating optical system that revolves the optical axes of the lenses coaxially with each other.

In the present invention configured as described above,
A detection light for detecting a planned processing position of a workpiece at a processing position is generated from a detection light source, and the detection light is decentered by a certain distance from a central axis by a rotating optical system and revolved. The detection means detects a change in the detection light from the workpiece and generates a detection signal corresponding to the planned processing position.

On the other hand, the optical axis of the processing laser light is also the detection light,
It is revolved on a workpiece coaxially by a rotating optical system. The control means oscillates the processing laser light based on the detection signal indicating the processing expected position of the detection means and irradiates the processing laser light on the workpiece.

Thus, even if the positioning trajectory of the robot or the like deviates from the expected processing position, if the expected processing position is within the revolution radius of the detection light, the detected light and the detecting means can detect the expected processing position, thereby ensuring the processing. It is possible to irradiate the processing scheduled position with laser light. In other words, welding at the planned processing position can be reliably performed without changing the control of the robot or the like.

Further, since the planned processing position can be detected by a simple change in the detection light, high-speed processing can be performed without requiring spatial processing such as image processing.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a laser welding apparatus and a laser welding method according to the present invention will be described with reference to FIGS. FIG. 1 is a schematic configuration diagram of a laser welding apparatus according to one embodiment of the present invention. In FIG. 1, a laser welding device according to an embodiment of the present invention includes a laser head 3.
A laser oscillator 3 including a laser power source 1 and a laser power source 32;
An optical fiber 4, a processing head 5 on which a processing optical system and a detection system are mounted, and laser oscillation control means 6 for controlling laser oscillation based on the detection light are provided.

Further, the processing head 5 is relatively moved with respect to the workpiece 1 which is a workpiece.
Are combined with a laser welding device. Robot 2
Is a commonly used articulated or orthogonal robot, which is usually composed of a mechanical unit 21 and a controller 22. In addition to controlling the movement of the mechanical unit 21, the laser oscillator 3 starts / ends machining. Perform simple control such as.

The laser power supply 32 is connected to the laser controller 3
20, a stabilizing power supply 321, a capacitor unit 322, and a switch unit 323. In the laser power supply 32, first, an AC voltage supplied from an external AC power supply is supplied to the stabilizing power supply section 321, changed to a DC voltage according to a voltage value instructed by the laser controller 320, and supplied to the capacitor section 322. .

The charge supplied to the capacitor unit 322 at the above voltage value is supplied to the laser excitation lamp provided in the laser head 31 by opening and closing the switch unit 323 with a predetermined pulse width according to a trigger signal FP from the laser controller 320. 310. The pulsed charges cause the flash lamp 310 to emit light, thereby exciting the laser medium and emitting pulsed laser light.

The processing head 5 is provided with a detection light source described later, a laser diode 510 and a photodiode 511 as detection means, and a detection signal from the photodiode 511 is input to the oscillation control means 6. When the detection signal is input to the oscillation control means 6, the oscillation control means 6 outputs a trigger signal TP to the laser controller 320 in the laser power supply 32. The laser controller 320 is supplied with a processing start / end command signal from the controller 22, and its operation is controlled by this signal.

As shown in FIG. 2, the control means 6 is provided with a comparator 61 as a comparison means composed of an operational amplifier and the like, a delay circuit 62 as a delay means, and a trigger circuit 63.

The detection signal from the photodiode 511 is supplied to a comparator 61, which binarizes the signal to generate a rectangular signal, and a delay circuit 62 gives a delay time to the rectangular signal. Subsequently, the rectangular wave signal delayed by the delay circuit 62 is supplied to a trigger circuit 63, and the trigger circuit 63 generates a trigger signal TP for laser irradiation from the rectangular wave signal. Then, the trigger signal TP is output to the laser controller 320.

The laser controller 320 to which the trigger signal TP has been input operates the switch section 323 based on the trigger signal P according to the above-described process, and the pulsed laser light is oscillated from the excitation lamp 310.

FIG. 3 is an internal configuration diagram of the processing head 5. As described below, the processing head 5 includes a detection optical system (a) for detecting a processing position, a processing optical system (b) for laser processing, and an optical system for both processing position detection and laser processing. (C).

(A) Detection Optical System The detection optical system includes a laser diode 51 as a detection light source.
0 (hereinafter abbreviated as LD510), photodiode 511 (hereinafter abbreviated as PD511) for detecting reflected light, LD51
A polarizing prism 512 is provided to reflect the laser light from 0 and pass the reflected light from the work 1. The detection optical system includes a lens 513 that collimates the laser light from the LD 510 and forms an image of the reflected light from the work 1 on the PD 511, a quarter-wave plate 514 that changes the polarization direction of the passing laser light, and the LD 510. A wedge substrate 515 for decentering the irradiation position of the laser light, and a parallel plane substrate 516 for moving the paths of the incident light and the reflected light in parallel.

(B) Processing Optical System The processing optical system includes a lens 520 for collimating the laser light output from the optical fiber 4, a wedge substrate 521 for deviating the irradiation position of the processing laser light, and a light emitting direction of the processing laser. A parallel plane substrate 522 for making a right angle to the work 1 and a bending mirror 523 for bending the optical axis of the processing laser toward the detection optical system are provided.

(C) Dual-Use Optical System The optical system used in both the detection optical system and the processing optical system includes:
The dichroic mirror 53 and the LD 51 which transmit the light of the detection LD 510 and have a reflection characteristic with respect to the processing laser light.
A condenser lens 54 for condensing the laser light from 0 and the processing laser light respectively is provided. The laser light and the processing laser light from the LD 510 are irradiated on the surface of the work 1 eccentrically with respect to the central axis O. In order to revolve the irradiation position around the central axis O, the wedge substrate 5
A motor 55 is provided for simultaneously rotating the flat substrates 15, 521 and the parallel flat substrates 516, 522.

The function of the processing head 5 will be described below. First, the beam of the pulsed laser light output from the laser head 31 is input to the optical fiber 4,
Is collimated by the lens 520 into a substantially parallel beam. The parallel beam becomes a parallel beam inclined by a certain angle by the wedge substrate 521, and is translated by the parallel plane substrate 522 so that the optical axis of the parallel beam passes through the front focus F of the condenser lens 54.

The direction of the laser beam translated by the parallel plane substrate 522 is changed by the bending mirror 523 and the dichroic mirror 53, and the condensing lens 54.
The light is incident obliquely. Since the laser beam incident on the condenser lens 54 passes through the front focus F, the position where the laser beam is condensed and incident on the work 1 is perpendicular to the work 1 and deviated from the central axis O of the condenser lens 54. Position.

The wedge substrate 5 is driven by the motor 55.
21 and the parallel plane substrate 522, the work 1
The irradiation position of the laser beam condensed on the orbit revolves at a position separated by a distance L1 about the central axis O.

That is, the optical axis of the laser beam emitted from the laser head 31 revolves around the central axis O at a position separated by a distance L1 from the central axis O. When the laser light is actually emitted from the laser head 31, the laser beam is applied to the position of the optical axis on the work 1 at the time when the laser light is emitted.

On the other hand, the laser light output from the LD 510 is reflected by the polarizing prism 512, collimated by the lens 513, passed through the quarter-wave plate 514, where the polarization plane is rotated by 45 °. The laser beam that has passed through the 波長 wavelength plate 514 is tilted in direction by the wedge substrate 515, is translated by the parallel plane substrate 516 so as to pass through the front focus F of the condenser lens 54, and is inclined by the condenser lens 54. And a certain distance L from the central axis O
Light is condensed perpendicularly to the work 1 at a position separated by two.

Here, the light reflected from the surface of the work 1 travels along the same path as that at the time of incidence, and the condenser lens 54, the dichroic mirror 53, the parallel plane substrate 516, and the wedge substrate 5
15 and the polarization plane is again changed to 4 by the 波長 wavelength plate 514.
Rotate 5 °. And the light whose polarization plane is rotated by 45 ° is
The light becomes a light whose polarization plane is rotated by 90 ° as compared with the light exiting from the LD 510, and enters the polarizing prism 512 via the lens 513.

The polarizing prism 512 has a characteristic of reflecting light having a predetermined polarization plane and transmitting light having a polarization plane rotated by 90 ° from the predetermined polarization plane, so that a quarter-wave plate 514 and a lens 513 are provided. Through the polarizing prism 512
Is reflected by the polarizing prism 512, and the reflected light
It is collected on D511.

The wedge substrate 5 is driven by the motor 55.
When the substrate 15 and the parallel plane substrate 516 are rotated, the optical axis (irradiation position) of the converged detection laser light revolves around the center axis O at a distance L2.

As described above, the detection light output from the inside of the processing head 5 and the processing laser light output from the laser head 31 are both distances (L1, L2) about the center axis O on the work 1. Orbit) only at a distance. At this time, the phases of the respective lights are the wedge substrates 515 and 5
21, for example, the wedge substrate 515
And 521 face each other to form a plane-symmetric shape,
The 180 ° phase is different, and the phase of each light irradiation position is also shifted by 180 °.

The eccentric distance from the central axis O is determined by the inclination angle of the wedge substrates 515 and 521, and has the relationship shown in the following equation (1). L = (n−1) · f · tan α (1) where L is the eccentric distance, and n is the wedge substrates 515 and 52
1 is a refractive index, f is a focal length of the condenser lens 54, and α is an inclination angle of the wedge substrates 515 and 521.

In this case, the eccentric distances may be equal or different, but it is preferable that L2 ≧ L1. This is because if L2 ≧ L1, the detection light is the same as or ahead of the optical axis of the processing light, and the processing accuracy can be improved.

The operation of the pulse laser welding apparatus having the above configuration will be described. First, the irradiation function of the processing laser is turned on from the controller 22 to the laser controller 320.
And the motor 55 inside the processing head 5
Is issued, and the irradiation position of the detection laser and the optical axis of the processing laser are revolved.

Next, the robot 2 starts to move the center axis O of the processing head 5 along the abutting surface of the work 1. The process from the detection of the butted surface to the irradiation of the processing laser at this time will be described with reference to FIGS.

FIG. 4 is a view of the work 1 as viewed from the laser incident side. The solid line in the figure is the abutting surface, and the dotted line is the trajectory that the center axis O of the processing head 5 is to be moved by the robot 2. At the point ()), the butting surface and the movement locus coincide with each other, and at the point (B), they are shifted.

The irradiation positions of the detection laser and the processing laser are 180 ° out of phase with each other. A circle indicates the irradiation position of the detection laser, and a black circle indicates the position of the optical axis of the processing laser. Each of the irradiation position and the optical axis position is rotated about the central axis O of the processing head 5, and the detection laser is continuously irradiated. The reflected light of the revolving motion of this detection laser is PD
FIG. 5 shows a waveform detected by the PD 511.

As shown in FIG. 5A, since the detection laser is reflected on the surface of the work 1 and detected by the PD 511, the output from the PD 511 is large, and a gap or the like exists on the abutting surface. Therefore, the amount of reflected light decreases and the output decreases.

Here, in FIG. 4, the detection laser is 1
While passing through the abutting surface twice during rotation, the lower passing point in FIG. 4 has already been irradiated with the processing laser, and the change in reflected light has become smaller. That is, the portion indicated by α in FIG. 5A corresponds to the butted surface that has not been irradiated with the processing laser, and the portion indicated by β corresponds to the butted surface that has been irradiated with the processing laser.

The output from the PD 511 shown in FIG. 5A is binarized by the comparator 61 of the control means 6 based on the threshold level Vth, and becomes a rectangular wave signal as shown in FIG. 5B. . The rectangular wave signal binarized by the comparator 61 is shifted by a delay time t by a delay circuit 62 as shown in FIG.

The signal shifted by the delay time t by the delay circuit 62 is, as shown in FIG. 5D, a signal whose falling and rising intervals are smaller than a predetermined interval to be described later by the trigger circuit 63. Then, only a small signal is output to the laser controller 320 as the trigger signal TP.

The laser controller 320 sends a trigger signal TP from the oscillation control means 6 to the switch section 323 to perform switching, and the electric charge of the capacitor section 322 is supplied to the lamp 310. Then, as shown in FIG. 5E, a pulsed laser oscillates from the lamp 310. Here, since the laser irradiation time is short, FIG.
Are shown as lines.

Here, the delay time t shown in FIG.
Is related to the phase difference θ between the irradiation position of the detection laser and the optical axis of the processing laser on the work 1 and is determined by the following equation (2). t = θ / 2πf + t0 (2) where f is the number of revolutions of the irradiation position of the detection laser (the optical axis of the processing laser), and t0 is the delay time from the input of the trigger signal TP to the irradiation of the laser. is there. Note that the rotation speed f is a rotation speed synchronized with the frequency of the pulse laser.

According to the above equation (2), when the butting surface is detected by the detecting laser, the processing laser is irradiated so as to match the butting surface. Further, since the processing head 5 moves during the delay time t, the processing laser is irradiated with a delay from the actual detection position. Therefore, it is needless to say that it is better to reduce the phase difference between the detection laser and the processing laser. For example, if the phase difference is 90
° is desirable.

As shown in FIG. 4B, even if the center axis O of the processing head 5 moves out of the abutting surface, the revolving radii of the detection and processing lasers (L in the example of FIG. 4).
If there is an abutting surface within 1, L2), the abutting surface can be detected by using the detection laser, and the abutting surface can be reliably irradiated with the processing laser by the above-described process.

Therefore, even when the accuracy of the moving axis of the robot or the like is not good, the butted surface can be detected. In addition, the orbital radius of the laser for detection and processing is adjusted to the accuracy of the moving axis of the robot or the like used,
It is also possible to set.

When the rotational movement of the detection and processing lasers is increased, the laser is irradiated in accordance with the number of rotations, and the welding is performed in one pulse depending on the feed rate. And reliable butt welding can be performed.

Here, the reason why the trigger circuit 63 extracts a signal whose interval between the fall and the rise is smaller than a predetermined interval as the trigger signal TP will be described with reference to FIGS. 6 and 7. FIG. FIG. 6 shows a case where the processing start position is the end face of the work 1. In this case, since the reflected light of the detection laser does not return at a position separated from the end face, the output from the PD 511 becomes low, and the waveform becomes as shown in FIG. That is, the signal corresponding to the portion deviating from the end surface of the work 1 is lower than the threshold level Vth, and the interval T from the fall to the rise is determined by the signal (part of α) due to the light reflected from the butted surface. )).

Therefore, if a limit is provided for this interval, the irradiation of the processing laser at a portion deviating from the end face of the work 1 is limited.

This interval can be set, for example, to the time when the spot diameter of the detection laser beam passes through a certain point on the work 1. This interval can also be adjusted by the actual butting interval.

The comparator 61 may determine whether the interval between the fall and the rise is smaller than the predetermined interval in the trigger circuit 63. An interval determination circuit may be provided.

As described above, according to one embodiment of the present invention, the irradiation position of the detection laser light on the work 1 and the optical axis of the processing laser light on the work 1 are set to the central axis O of the condenser lens. Are rotated at predetermined distances L2 and L1 from the laser light.
When the butting surface is detected, and when the optical axis of the processing laser beam is located at the detected position, the processing laser is irradiated to the work 1 to weld the butting surface, so that the robot with low positioning accuracy can be used. It is possible to realize a laser welding apparatus and a laser welding method that can be combined and that can perform laser welding while performing position correction by simple means that does not change the control unit such as a robot.

Further, since the position to be processed can be detected by a simple change of the detection light, high-speed processing is possible without requiring spatial processing such as image processing.

[0063]

Since the present invention is configured as described above, it has the following effects. It can detect changes in the workpiece surface at high speed in response to machining position errors of robots and the like combined for laser welding, and can be combined with robots with low positioning accuracy, and without changing the control unit of the robot etc. A laser welding apparatus and a laser welding method capable of performing laser welding while performing position correction based on the above detection by any means can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a laser welding apparatus according to an embodiment of the present invention.

FIG. 2 is an internal configuration diagram of a laser oscillation control unit in the example of FIG.

FIG. 3 is an internal configuration diagram of a processing head in the example of FIG. 1;

FIG. 4 is a diagram illustrating a workpiece abutting surface and a planned movement locus of a processing head.

FIG. 5 is a time chart of a signal from detection of a butted surface to laser irradiation.

FIG. 6 is a diagram illustrating a movement locus of a detection laser on a work end surface.

FIG. 7 is a diagram showing a detection signal waveform at a work end surface.

FIG. 8 is a schematic configuration diagram of a conventional laser welding apparatus.

FIG. 9 is a diagram illustrating a workpiece abutting surface and a movement locus of a robot.

[Description of sign]

 Reference Signs List 1 work 2 robot 3 laser oscillator 4 optical fiber 5 processing head 6 laser oscillation control circuit 21 mechanism unit 22 controller 31 laser head 32 laser power supply 53 dichroic mirror 54 condensing lens 55 motor 61 comparator 62 delay circuit 63 trigger circuit 310 excitation lamp 320 Laser controller 321 Stabilized power supply 322 Capacitor section 323 Switch section 510 Laser diode 511 Photodiode 512 Polarizing prism 513, 520 Lens 515, 521 Wedge substrate 516, 522 Parallel plane substrate 523 Bending mirror

Claims (2)

[Claims] 1. A laser welding method for oscillating a pulsed processing laser beam, irradiating the processing laser beam onto the workpiece, and welding the workpiece, detecting a change in the surface of the workpiece. And the optical axes of the detection light and the processing laser light are revolved coaxially on the surface of the workpiece to detect reflected light of the detection light from the workpiece. A laser welding method comprising: detecting a planned processing position of the workpiece; and irradiating the detected processing position with the processing laser to process the workpiece. 2. A laser welding apparatus comprising: a laser oscillator for oscillating a pulsed processing laser beam; and a processing optical system for guiding the processing laser beam to a processing position of the workpiece. A detection light source that generates detection light for detecting a change in the surface of the workpiece, detection means that detects reflected light of the detection light from the workpiece, and generates a detection signal corresponding to the detected light, Control means for controlling the oscillation of the pulsed laser beam so that the laser beam for processing is irradiated to the position to be processed of the workpiece based on the signal; and the detection light and the processing on the surface of the workpiece. A rotary optical system that revolves the optical axis of the laser light for use coaxially with each other.