JPH10249558A - Laser processing apparatus and laser processing method - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To eliminate a plume generated by laser processing and a signal caused by light emission of a molten material, the frequency of a laser beam is not restricted, and a plume generated by laser processing is not restricted. Provided is a laser processing apparatus and a processing method in which detection accuracy of detection light is not affected by the wavelength or intensity of light emission of a melt. A light detector (12) emitted from a detection light source (122) is provided.
6, the detection light 200 (work 1 which is a workpiece)
Aside from the surface information (including information on the surface), the photodetector 129 detects light including light emitted from a plume or a melt generated by laser beam irradiation, and outputs a corresponding detection signal B (B ^* ) to the photodetector 126. The detection signal C is generated by subtracting the detection signal C from the detection signal A. Then, the laser beam 100 is oscillated based on the detection signal C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a laser processing apparatus and a laser processing method capable of processing a desired processing position at high speed and accurately.

[0002]

2. Description of the Related Art Processing using pulsed laser light includes processing methods such as cutting, drilling, and welding.
It is used in manufacturing processes in various fields such as semiconductor devices. Among them, Japanese Patent Application Laid-Open Nos. 6-142968 and 7-284968 disclose conventional techniques relating to a laser processing apparatus or a laser processing method suitable for cutting and removing a dam bar of a semiconductor device.

[0003] The prior art described in Japanese Patent Application Laid-Open No. 6-142968 (hereinafter referred to as a first prior art) employs a detection optical system (light detecting means) arranged substantially coaxially with the optical axis of a processing optical system. The presence or absence of material in the workpiece, that is, the arrangement of the leads near the dam bar is optically detected based on the switching of light and dark, the detection signal is rectangularized, and a certain delay time is added to the rectangular signal. It controls the oscillation of the pulsed laser light based on the signal given the delay time. That is, when the dam bar of the semiconductor device is cut by this method, the arrangement state of the leads is directly visually detected, and the irradiation of the pulse laser light is immediately performed using the data. Accordingly, the dam bars are sequentially cut only by moving the optical axis of the laser beam (hereinafter, referred to as the laser optical axis) with respect to the workpiece, and the processing can be performed reliably and at high speed.

In the first prior art, there is a concern that light such as a plume generated by laser processing may be erroneously detected as reflected light or transmitted light based on the presence or absence of a material of a workpiece. There is a concern that a laser beam is oscillated by the detected signal, and laser processing is performed at an incorrect position other than a predetermined laser processing position.

On the other hand, in Japanese Patent Application Laid-Open No. Hei 7-284968 (hereinafter referred to as a second prior art), a gate circuit for ignoring a signal based on light emission within a predetermined time is added or a band-pass filter is provided. For example, a method of removing a signal caused by light emission (plume or the like) generated by laser processing has been disclosed. According to the second conventional technique, laser processing is not unnecessarily performed based on light such as a plume generated by laser processing.

[0006]

In the second prior art, the gate width of a gate signal for ignoring light emission generated by laser processing is determined based on the period of detection light reflected or passed from a lead. Time) is limited. That is, as shown in FIG. 9, a gate width WG equal to or less than the period S1 of the detection light reflected or transmitted from the workpiece (eg, a lead of a semiconductor lead frame) is the maximum value of the settable gate width. In actual processing, laser light is emitted after a certain delay time from the rise of a signal based on detection light (FIG. 9A) reflected or passed from the workpiece, and as a result, a plume having an emission time Wp is emitted. (FIG. 9
(B)). At this time, the signal accompanying the plume within the preset gate width WG is ignored. In this case, the settable gate width WG is less than the period S1 of the detection light reflected or transmitted from the workpiece. Needless to say.

If the period S1 of the detection light reflected or transmitted from the workpiece is 0.01 s (corresponding to 100 Hz as the repetition frequency in the laser oscillator), the gate width WG can be set to 0.01 s or less. .

The present inventors have conducted experiments to determine the gate width WG.
When the pulse width of one pulse of laser light was set to 0.1 to 1.0 ms, the
When cutting a metal material with a thickness of about 0.2 mm,
In practice, it has been confirmed that unless the gate width WG is set to about 5 to 10 ms, erroneous irradiation due to light emission accompanying laser processing cannot be completely avoided.

As described above, the required gate width W is smaller than the pulse width of 0.1 to 1.0 ms per laser light pulse.
The reason why G becomes long as 5 to 10 ms is that not only the plume emits light due to laser processing, but also the metal of the work being melted and scattered after the irradiation of one pulse of laser light emits light for a long time. is there. That is, in actual processing,
Erroneous detection is performed by the emission of the melt of the workpiece, rather than the emission of the plume, and the possibility of the laser beam erroneously oscillating is higher. According to the above experimental results, the period S1 of the detection light reflected or transmitted from the workpiece can be used only in the range of 5 to 10 ms or more (that is, the above-mentioned WG or more). , Leading to a reduction in processing efficiency.

In the case where a signal caused by light emission generated during processing is deleted by the bandpass filter, the wavelength of light due to light emission of the plume and the melt is detected depending on the components of the workpiece and the laser output. In some cases, the light level is about the same as the wavelength of the light, and in other cases, the light emission is stronger than the detection light.Therefore, it is not possible to reduce the level of the signal accompanying the emission of the plume or melt to an appropriate level that can be deleted. Is also conceivable. If the level of the signal accompanying the light emission of the plume or the melt cannot be sufficiently reduced, the laser beam is erroneously irradiated by the erroneously detected signal.

An object of the present invention is to eliminate a plume generated by laser processing and a signal caused by light emission of a molten material without restricting the frequency of a laser beam. An object of the present invention is to provide a laser processing apparatus and a processing method in which the detection accuracy of detection light is not affected by the wavelength or intensity of light emission of a melt.

[0012]

According to the present invention, there is provided the following arrangement for achieving the above object.

(1) A laser oscillator that oscillates pulsed laser light, a processing optical system that guides the laser light to a processing position of the workpiece, and a transport that moves the workpiece and determines the processing position Means for detecting a presence or absence of a workpiece at the processing position, and a first light source corresponding to reflected light or transmitted light of the detection light from the processing position. First detection means for generating a detection signal of the first type, second detection means for detecting light generated by the laser light irradiation and generating a second detection signal corresponding to the light, and the first detection Processing light removing means for obtaining a third detection signal from a difference between the signal and the second detection signal, and a laser beam for irradiating a laser beam to a predetermined processing position of the workpiece based on the third detection signal Suppresses light oscillation Laser processing apparatus characterized by a control unit.

(2) A laser processing method for processing a workpiece by moving the workpiece to determine a processing position, and irradiating a pulsed laser beam from the laser oscillator to the processing position to process the workpiece. The processing position is irradiated with detection light for detecting the presence or absence of a workpiece, and reflected light or passing light of the detection light from the processing position is extracted to generate a first detection signal, which is generated by the laser light irradiation. And detecting a second detection signal corresponding to the detected light, and subtracting a second detection signal from the first detection signal. And generating a third detection signal based only on reflected light or passing light of the detection light from the processing position, and at a timing based on the third detection signal, a predetermined processing position of the workpiece. To Laser processing method characterized by irradiating laser light.

In the present invention configured as described in (1) and (2) above, detection light for detecting the presence or absence of the workpiece at the processing position is generated from the detection light source, and the first detection means is provided. Detects reflected light or transmitted light of the detection light from the processing position, and generates a first detection signal corresponding thereto. At this time, the first detecting means includes, in addition to reflected light or transmitted light (including information on the surface of the workpiece) of the detection light from the processing position, disturbance light (plume or melted light) accompanying the laser processing. (Emission). In addition to the first detection signal, the second detection means detects light generated by laser beam irradiation, that is, light including light emitted from a plume or a melt, and detects a second light corresponding to the light. Generate a detection signal. Then, the processing light removing means subtracts the second detection signal from the first detection signal to obtain a third detection signal. Thereby, disturbance of light due to laser processing out of light from the workpiece is removed, and the third detection signal is a signal based only on reflected light or transmitted light of detection light from the processing position. Further, the control means suppresses the oscillation of the laser light so that the predetermined processing position of the workpiece is irradiated with the laser light based on the third detection signal.

Therefore, the laser light is not oscillated based on the detection signal by the light accompanying the laser processing, and the laser light is not unnecessarily irradiated to the wrong position other than the predetermined processing position. Of course, since the gate signal is not used to ignore the light emission generated by the laser processing, the frequency of the laser light is not restricted by eliminating the disturbance light. Further, since a bandpass filter is not used to remove a signal caused by the disturbance light, the detection accuracy of the detection light is not affected by the wavelength and intensity of the disturbance light.

Further, since the laser beam is applied to a position separated by a certain distance from the position where the information on the presence / absence of the workpiece is detected, not only when the processing positions are at equal intervals but also when the processing positions are not at equal intervals. Thus, a desired position to be cut can be processed reliably and at high speed in accordance with information on the presence or absence of a workpiece.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a laser processing apparatus and a laser processing method according to the present invention will be described with reference to FIGS. However, in the following, the removal of the dam bar portion of an IC package having pins at regular intervals will be described.

As shown in FIG. 1, a laser processing apparatus according to the present embodiment is equipped with a laser oscillator 10 including a laser head 11 and a laser power supply 13, a processing head 12, and a work 1 as a workpiece. A control having an XY table 21 as a transport means for moving in a horizontal plane (XY plane), a Z table 22 for moving the laser head 11 and the processing head 12 in the vertical direction (Z axis direction), a main controller 23 and a trigger unit 24 Unit 2
5. A detection signal processing circuit 310 is provided. The main controller 23 automatically controls the movement of the XY table 21 in the horizontal plane, the movement of the Z table 22 in the vertical direction, and the oscillation of the laser oscillator 10.

The laser power supply 13 includes a stabilized power supply 130,
Capacitor section 131, switch section 132, AC power supply 13
3 and a laser controller 26. In the laser power supply 13, first, the AC current supplied from the AC power supply 133 is supplied to the stabilizing power supply unit 130, changed to DC according to the voltage value instructed by the laser controller 26, and supplied to the capacitor unit 131. Capacitor part 1
The charge supplied to the 31 at the above voltage value is supplied to the excitation lamp 110 provided in the laser head 11 by opening and closing the switch unit 132 according to a trigger signal TP ₂ (described later) from the laser controller 26. The excitation lamp emits light by the pulse-like charges, thereby exciting the laser medium and emitting a pulse-like laser beam.

The laser head 11 shown in FIG. 1 has a built-in beam shutter 111. The beam shutter 111 turns on / off a pulsed laser beam emitted from the laser oscillator 10 by opening and closing.
Then, the irradiation of the laser light to the work 1 is controlled. That is, the beam shutter 111 is opened when the workpiece 1 is processed, and the beam shutter 111 is opened when the workpiece 1 is not processed.
Close. The operation time of the beam shutter 111 is 1
It is about 00 to 300 msec. Further, the ON / OFF control of the beam shutter 111 is performed by the laser controller 26, but can be performed by the main controller 23 via the laser controller 26.

As shown in FIG. 2, a bending mirror 120 and a condenser lens 121 having high reflectance characteristics with respect to the wavelength of a laser beam are provided inside the processing head 12, which is a conventional laser processing apparatus. The configuration is the same as that described above.
In this embodiment, a detection light source 122 that generates laser light as detection light, a collimator lens 123, a half mirror 124, an imaging lens 125, and a photodetector 126
A detection optical system 127 constituted by (first detection means) is added. As the detection light source 122, a laser light source such as a laser diode (semiconductor laser) is used. This detection optical system 127 is basically similar in configuration to the optical system of an optical pickup unit that reads a disk signal of a CD player. ing. It goes without saying that the laser light used as the detection light is different from the laser light for performing the laser processing. A signal from the detection optical system 127 is input to the detection signal processing circuit 310, and a signal from the detection signal processing circuit 310 is input to the trigger unit 24.

As shown in FIGS. 1 and 2, an imaging lens 128 and a photodetector 129 are provided beside the processing head 12.
(Second detecting means), and light generated by laser light irradiation (ie, light including light emitted from a plume or a melt)
Is detected by the photodetector 129. The imaging lens 128
As shown in FIG. 3, the photodetector 129 is set at a position outside the reflection range R1 of the detection light 200 and within the range R2 of light emission from the plume and the melt.

As shown in FIG. 4, the detection signal processing circuit 31
For 0, a detection signal comparison circuit 312 to which the detection signal A from the photodetector 126 is input and a signal level adjustment circuit 311 to which the detection signal B from the photodetector 129 are input are provided. The detection signal B from the photodetector 129 is adjusted by the signal level adjustment circuit 311 so as to have the same level as the signal level of the detection signal A from the photodetector 126, and is input to the detection signal comparison circuit 312 as the detection signal B ^*. Is done.
Then, in the detection signal comparison circuit 312, the detection signal A
Is subtracted from the detection signal B ^* , and is output as a detection signal C from which the disturbance of the plume and the emission of the melt is removed.

As shown in FIG. 5, the trigger unit 24 includes a comparator 241 and a trigger signal generation circuit 2.
42, a delay circuit 243 is provided. In the trigger unit 24, the detection signal C from the detection signal comparison circuit 312 is binarized by a threshold value V _TH (see FIG. 7 or 8) in the comparator 241 to generate a rectangular wave signal TP. The signal generation circuit 242 outputs a trigger signal TP ₀ synchronized with the falling edge of the rectangular wave signal TP, and the trigger signal TP ₀ is input to the delay circuit 243 where the delay time commanded by the main controller 23 T _D is given, the signal TP ₁
Is output to the laser controller 26.

As shown in FIG. 6, the laser controller 26 includes an input / output unit 260, a central processing unit 261, and a trigger circuit 262. Trigger circuit 262
Generates a trigger signal TP ₂ having a pulse width instructed from the main controller 23 to the central processing unit 261 in synchronization with the rise of the trigger signal TP ₁ from the trigger unit 24, and this trigger signal TP ₂ is transmitted to the switch unit 132. Is entered. The voltage value of the electric charge supplied to the capacitor unit 131 is input from the input / output unit 260 to the central processing unit 261, and is instructed from the central processing unit 261 to the stabilized power supply unit 130. Thereafter, the laser light oscillates according to the above-described process.

Returning to FIG. 2, the functions of the processing head 12 and the detection optical system 127 will be described. First, the laser beam 100 oscillated from the laser head 11 is transmitted to a bending mirror 120.
Then, the direction is changed, and the light is condensed by the condenser lens 121 and irradiated onto the work 1. The detection light 200 emitted from the detection light source 122 is made parallel by the collimator lens 123, reflected by the half mirror 124, passes through the bending mirror 120, and passes through the condensing lens 121 to the work 1.
An image is formed with a minute spot on the top. However, the detection optical system 12
By adjusting 7, the spot forms an image at a position separated by a distance δd from the condensing position of the laser beam 100 for laser processing oscillated from the laser head 11. And
The detection light 200 reflected on the surface of the work 1 is
21, bending mirror 120, half mirror 124
, And is collected by a photodetector 126 by an imaging lens 125, and information on the surface of the work 1 is detected as an electric signal. In the present embodiment, since a laser light source is used as the detection light source 122, the laser light can be reduced to a very small size by the collimator lens 123 and the imaging lens 125, and when detecting information (the presence or absence of material) on the surface of the work 1 In addition, the rise (response) of the signal is faster, and detection can be performed with high resolution.

At this time, the condenser lens 121 and the imaging lens 1
25, the detection light 200 on the surface of the work 1
Is formed at the position of the photodetector 126. Also, as shown in FIG. 7, the spot of the detection light 200 hits a portion slightly outside the dam bar 2.
Laser beam 100 for laser processing from laser head 11
(See FIG. 2). Accordingly, the photodetector 126 can detect the presence or absence of the pin, that is, the portion (hereinafter, referred to as a web portion) 4 where the pin exists and the slit portion 3. On the other hand, the laser beam 100 used for laser processing irradiates almost the center of the dam bar. Therefore, the dam bar 2 to be cut can be cut based on the detection signal from the photo sensor 126 as described later.

The operation of the laser processing apparatus having the above configuration will be described. Work 1 which is the lead frame of IC
When the Y table 21 is moved at a constant speed in, for example, the positive direction of the X axis, the detection light 20 narrowed to a minute spot
Numeral 0 moves on the work 1 along a locus 5 shown in FIG.
As a result, of the detection signals detected by the photodetector 126, the change of the detection signal caused by the detection light 200 from the detection light source 122 becomes a high output in the web section 4 and a low output in the slit section 3. However, the X axis and the Y axis are determined as shown in FIG. At this time, the web part 4 and the slit part 3 of the work 1
Are arranged at an equal pitch, the detection signal when the XY table moves at a constant speed is detected as a waveform of a constant period. When the web portion 4 and the slit portion 3 of the work 1 are not arranged at an equal pitch, The detection signal is detected as a waveform having a time change proportional to the change in pitch.

Further, in the present embodiment, the laser beam 100 is applied to the center of the dam bar portion 2 to remove the dam bar as described later. However, when processing is performed by irradiating the laser beam to the workpiece as described above, From the processing position, light emission called a plume due to light due to the oxidation reaction with the plume accompanies. In addition, light is emitted from a molten metal that is scattered while being melted and burned by laser light irradiation. Therefore, the photodetector 1
As shown in FIG. 8, the detection signal A detected at 26 has the above-mentioned plume (indicated by P in the figure) and melt emission (see FIG. The waveform (disturbance) associated with the middle M is superimposed. However, in FIG. 8, the web portion 4 and the slit portion 3 when the work 1 is moved at a constant speed are schematically shown as time changes.

On the other hand, the detection signal B from the photodetector 129
Is adjusted by the signal level adjustment circuit 311 so as to be the same level as the signal level of the detection signal A to become the detection signal B ^* , and the detection signal B ^* is subtracted from the detection signal A by the detection signal comparison circuit 312, and the The detection signal C from which the waveform (disturbance) associated with (P) and the melt emission (M) is removed is generated.

The detection signal C input from the detection signal comparison circuit 312 to the comparator 241 of the trigger unit 24
Is binarized based on a predetermined threshold value V _TH indicated by a broken line in FIG.
42 the trigger signal TP ₀ is output on the basis of the fall of the rectangular wave signal TP by. Trigger signal TP ₀ is input to the delay circuit 243, a command delay time T _D from the main controller 23 to the trigger signal TP ₀ is input to the laser configuration torus 26 as a trigger signal TP ₁ given. The detection signal from the photodetector 126 may be amplified by an amplifier before being input to the trigger unit 24.

Next, the trigger signal TP ₁ in the laser controller 26 is input to the trigger circuit 262, from the trigger circuit 262, the trigger signal TP ₂ in synchronization with the rising edge of the trigger signal TP ₁ is output. The pulse width of the trigger signal TP ₂ is indicated via the central processing unit 261 from the main controller 23 as described above. Moreover the trigger signal TP ₂ is input to the switch unit 132, the switch unit 132 in synchronization with the rising edge of the trigger signal TP ₂
Is turned off, and the condenser 13 is connected to the excitation lamp 110.
Electric charges are supplied from 1, the switch unit 132 is turned ON and further synchronization with the falling edge of the trigger signal TP _2, the supply of charge to the excitation lamp 110 is stopped. Above manner, pulsed laser light synchronized with the trigger signal TP ₂ to oscillate. Although the trigger signal TP ₂ and the laser light in the drawing actually have a pulse waveform having a certain width, the trigger signal TP ₂ and the laser light are shown in a linear shape in the drawing because their pulse widths are much shorter than other signals. .

In the above description, the reflected light of the detection light 200 reflected on the surface of the work 1 is detected by the photodetector 126, but the transmitted light of the detection light 200 transmitted through the work 1 is detected by the photodetector 126. You may make it.

In this embodiment as described above, light detection is performed separately from the detection light 200 (including information on the surface of the work 1 as a workpiece) emitted from the detection light source 122 and detected by the photodetector 126. Detector 129 detects light including light emitted from a plume or a melt generated by laser light irradiation,
The detection signal C is generated by subtracting the detection signal B (B ^* ) corresponding to the detection signal A from the detection signal A from the photodetector 126, so that the detection signal C is only reflected light or transmitted light of the detection light 200 from the processing position. The signal may be based on
Then, by oscillating the laser beam 100 based on the detection signal C, the laser beam is not oscillated based on the detection signal due to the laser processing light (light including light emitted from the plume or the melt). Unnecessary irradiation of the laser beam to an incorrect position other than the predetermined processing position is prevented. In addition, since the gate signal is not used to ignore light emission (light including light from a plume or a melt) generated by laser processing, the frequency of the laser light is restricted in order to eliminate disturbance light. There is no. Further, since a bandpass filter is not used to remove a signal caused by the disturbance light, the detection accuracy of the detection light is not affected by the wavelength and intensity of the disturbance light.

Further, since the laser beam is applied to a position separated by a certain distance from the position where the information on the presence / absence of the workpiece is detected, not only when the processing positions are at equal intervals but also when they are not at equal intervals. In addition, a desired position to be cut can be reliably and rapidly processed in accordance with information on the presence or absence of a workpiece.

[0037]

According to the present invention, detection means (second detection means) different from the first detection means detects light generated by laser beam irradiation and generates a corresponding second detection signal. And
Since the third detection signal is obtained by subtracting the second detection signal from the first detection signal, the third detection signal, which is a base for laser light oscillation, is reflected from the processing position by reflected light of the detection light or passed therethrough. It can be a signal based only on light. Therefore,
The laser light is not unnecessarily irradiated to a wrong position other than the predetermined processing position, the frequency of the laser light is not restricted to remove disturbance light, and the wavelength and intensity of the disturbance light are further reduced. It is possible to prevent the detection accuracy from being affected by the detection light.

Further, since the laser beam is applied to a position separated by a certain distance from the position where the information on the presence / absence of the workpiece is detected, not only when the processing positions are at equal intervals but also when they are not at equal intervals. In addition, a desired position to be cut can be reliably and rapidly processed in accordance with information on the presence or absence of a workpiece.

[Brief description of the drawings]

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

FIG. 2 is a schematic diagram of a configuration of a processing head and a detection optical system of FIG. 1;

FIG. 3 is a diagram showing a relationship between a reflection range of a detection light 200 and a range of light emission from a plume and a melt.

FIG. 4 is a diagram illustrating a configuration of a detection signal processing circuit of FIG. 1;

FIG. 5 is a diagram illustrating a configuration of a trigger unit in FIG. 1;

FIG. 6 is a diagram illustrating a configuration of a laser controller of FIG. 1;

FIG. 7 shows a dam bar portion of a lead frame and a photodetector 126.
FIG. 6 is a diagram showing a correspondence relationship with a detection signal from FIG.

FIG. 8 is a time chart from output of a detection signal from a photodetector to oscillation of laser light.

FIG. 9 is a diagram showing a relationship between a period of a detection signal from a photodetector and a gate width of a gate signal for ignoring light emission generated by laser processing in the second conventional technique.

[Explanation of symbols]

 Reference Signs List 1 work 2 dam bar 3 slit part 4 web part 5 locus 10 laser oscillator 11 laser head 12 processing head 13 laser power supply 21 XY table 22 Z table 23 main controller 24 trigger unit 25 control unit 26 laser controller 110 excitation lamp 120 bending mirror 121 collection Optical lens 122 Detection light source 123 Collimator lens 124 Half mirror 125 Imaging lens 126 Photodetector 127 Detection optical system 128 Imaging lens 129 Photodetector 130 Stabilized power supply 131 Capacitor section 132 Switch section 133 AC power supply 241 Comparator 242 Trigger signal generation Circuit 243 Delay circuit 261 Central processing unit 262 Trigger circuit 310 Detection signal processing circuit 311 Signal level adjustment circuit 312 Output signal comparison circuit P wave associated with the waveform M melt emission accompanying the plume

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Shigeyuki Sakurai 650, Kandate-cho, Tsuchiura-shi, Ibaraki Hitachi Construction Machinery Co., Ltd. (72) Inventor Yasushi Minomoto Yasushi Minatomoto 650, Kandamachi, Tsuchiura-shi, Ibaraki Hitachi Construction Machinery Engineering Co., Ltd.

Claims (2)

[Claims] 1. A laser oscillator that oscillates pulsed laser light, a processing optical system that guides the laser light to a processing position of a workpiece, and a transport unit that moves the workpiece and determines the processing position. A laser processing apparatus comprising: a detection light source that generates detection light for detecting the presence or absence of a workpiece at the processing position; and a first light corresponding to reflected light or transmitted light of the detection light from the processing position. First detection means for generating a detection signal of the first type, second detection means for detecting light generated by the laser light irradiation and generating a second detection signal corresponding to the light, and the first detection Processing light removing means for obtaining a third detection signal from a difference between the signal and the second detection signal, and a laser beam is irradiated to a predetermined processing position of the workpiece based on the third detection signal. Suppresses laser light oscillation A laser processing apparatus comprising: 2. A processing position is determined by moving a workpiece.
In a laser processing method of processing the workpiece by irradiating a pulsed laser beam to the processing position from a laser oscillator, irradiating the processing position with detection light for detecting the presence or absence of the workpiece at the processing position. Then, reflected light or passing light of the detection light from the processing position is extracted to generate a first detection signal, light generated by the laser light irradiation is detected, and a second detection signal corresponding to the light is detected. Causes
By subtracting the second detection signal from the first detection signal, of the light from the workpiece, a disturbance of light accompanying laser processing is removed, and reflected light or transmitted light of the detection light from the processing position. A laser processing method, comprising: generating a third detection signal based only on the third detection signal; and irradiating a predetermined processing position of the workpiece with laser light at a timing based on the third detection signal.