JP5246438B2 - Laser processing equipment - Google Patents

Description

  The present invention sets a plate-like workpiece on a table and rotates it, irradiates the workpiece with a pulse-train-shaped laser beam, and moves the irradiation position of the laser beam in the radial direction of the table. The present invention relates to a laser processing apparatus that forms a processing trace (pit or reaction trace) spirally on the surface of an object.

  Conventionally, a flat workpiece is set on a table and rotated to irradiate the workpiece with laser light, and the laser beam irradiation position is moved in the radial direction of the table to thereby move the surface of the workpiece. A laser processing apparatus that performs laser processing in a spiral manner is known. When forming a plurality of pits or reaction traces for forming pits (hereinafter collectively referred to as machining traces) on the entire surface of the workpiece, for example, as proposed in Patent Document 1, laser light is used. A pulse train signal (laser drive pulse train signal) is supplied to a laser light source that is an emission source of the laser beam, and a laser beam having a light emission waveform with respect to time is emitted.

  In this case, the rotation of the table is controlled so that the irradiation position of the laser beam is constant, and the period of the pulse train signal for driving the laser is fixed to a value determined from the set processing trace interval and the rotational linear velocity. If the distance that the irradiation position of the laser beam moves in the radial direction during one rotation of the table is set to the same value as the processing trace interval, the processing trace interval in the rotation direction and the processing trace interval in the radial direction become equal. Processing traces can be arranged uniformly over the entire surface of the object.

JP 2007-216263 A

  Such laser processing is used, for example, when an LED substrate is formed. An LED is formed by stacking thin films on a substrate by chemical vapor deposition. By forming irregularities on the surface of the substrate, the LED has a light extraction ratio that can be extracted to the outside with respect to the light generated in the light emitting layer. Light extraction efficiency can be improved. For this reason, fine processing traces are formed on the substrate by irradiating the pulsed laser beam, and the entire surface of the substrate is processed to be uneven.

  In conventional laser processing equipment, the pulse width, high-level laser intensity, radial movement processing trace, and rotational linear velocity of the pulse train emitted from the laser light source are set to be constant during laser processing. Has been. Therefore, the size and interval of the machining traces are always constant, and the plurality of machining traces are regularly arranged. Specifically, if the radial position changes, the distance that the laser light irradiation position moves during one rotation of the table, that is, the length of the circumference changes, so that when the formed processing trace portion is viewed in an enlarged manner, As shown in FIG. 11A, the formed machining traces are arranged on a parallelogram. On the other hand, when forming a processing mark on a substrate for manufacturing an LED, the processing marks are randomly formed as shown in FIG. 11B rather than regularly forming the processing marks as shown in FIG. There is also an experimental result that the light extraction efficiency may be higher in the case of forming the film. However, the conventional laser processing apparatus has a problem if the processing marks cannot be formed randomly.

  The present invention has been made to cope with the above-described problem, and provides a laser processing apparatus capable of randomly forming a processing mark over the entire processing region of a processing object. In addition, in the description of each constituent element of the present invention below, in order to facilitate understanding of the present invention, reference numerals of corresponding portions of the embodiment are described in parentheses, but each constituent element of the present invention is The present invention should not be construed as being limited to the configurations of the corresponding portions indicated by the reference numerals of the embodiments.

In order to achieve the above object, the present invention is characterized by a table (21) for setting a workpiece (OB), a rotating means (22) for rotating the table, and a processing set and rotated on the table. A processing head (30) that condenses and irradiates a laser beam emitted from a laser light source (31) onto an object by an objective lens (35), and a laser beam emitted from the processing head. Radial direction moving means (23-25) for moving the laser spot relative to the table in the radial direction of the table, and a pulse train-like drive signal are generated and supplied to the laser light source. Laser light source driving means (71, 72) for driving the laser light source so that the laser light is emitted, and along the radial direction of the table, In the laser machining apparatus to form a plurality of machining marks along the rotational direction of the Le, as between a plurality of processing traces formed along the radial direction of the table interval is changed randomly, a plurality of processing Random control means (43 to 46, 81 to 83) for controlling the formation of traces, which randomly changes the optical axis of the laser beam irradiated to the workpiece in the radial direction of the table. It is in providing.

According to this, in the processing marks pattern to be formed in a matrix in the object, machining marks pattern of intervals of a plurality of machining marks along the radial direction of the table is changed at random is formed. As a result, it is possible to satisfy a demand for a random processing trace pattern.

  Specifically, the radial random control means is arranged on the optical path of the laser light from the laser light source to the objective lens, and changes the optical axis of the laser light irradiated to the workpiece in the radial direction of the table. The acousto-optic modulation element or electro-optic modulation element (43) and the electro-optic modulation element or electro-optic modulation element are supplied with a randomly changing electric signal so that the acousto-optic modulation element or electro-optic modulation element is applied to the workpiece. The optical axis drive circuit (81) for controlling the acousto-optic modulation element or the electro-optic modulation element may be configured to randomly change the optical axis of the irradiated laser light in the radial direction of the table. According to this, since the time response of the acousto-optic modulation element or the electro-optic modulation element is high, it is effective when a processing trace with a fine interval is formed on the workpiece by rotating the table at a high speed.

  In addition, the radial direction random control means includes an actuator (44) for driving the objective lens to change the optical axis of the laser beam irradiated to the workpiece in the radial direction of the table, and an electric that randomly changes to the actuator. An optical axis drive circuit (82) that controls the actuator so as to change the optical axis of the laser beam irradiated to the workpiece by the objective lens randomly in the radial direction of the table by supplying a signal. Also good. In this case, for example, a tracking actuator can be used as the actuator, and it is easy to provide the processing head with the tracking actuator provided in the optical head used for recording / reproducing of the optical disk, and the optical axis drive circuit is also simple. Since it can be configured, the laser processing apparatus can be configured inexpensively and easily.

  Further, a radial direction random control means is disposed on the optical path of the laser light from the laser light source to the objective lens, and reflects the laser light from the laser light source and guides it to the objective lens, and drives the mirror. The actuator (46) for changing the optical axis of the laser beam irradiated to the workpiece in the radial direction of the table and an electrical signal that randomly changes to the actuator are supplied, and the mirror is irradiated to the workpiece. The optical axis drive circuit (83) for controlling the actuator may be configured so that the optical axis of the laser beam is changed randomly in the radial direction of the table. Also in this case, since the mirror, the actuator, and the optical axis drive circuit are configured relatively simply, the laser processing apparatus can be configured relatively inexpensively and simply.

Another feature of the present invention is random control means for controlling the formation of a plurality of machining traces such that the intervals between the plurality of machining traces formed along the radial direction of the table change randomly. Radial moving speed random control means (50) which electrically controls the radial moving means to randomly change the moving speed of the laser spot moving in the radial direction of the table relative to the table by the radial moving means. 62) . According to this, the interval between the plurality of machining traces formed along the radial direction of the table changes more randomly, and further, a request for a random machining trace pattern can be satisfied. Moreover, this case, since the radial moving means are provided in the laser machining apparatus is only electrically controlled, inexpensive and easily configured laser processing apparatus.

Another feature of the present invention is a random control means for controlling the formation of a plurality of machining traces such that the intervals between the plurality of machining traces formed along the rotation direction of the table change randomly. Rotation direction random control means (47, 84) for randomly changing the optical axis of the laser beam irradiated to the workpiece in the rotation direction of the table is provided. According to this, the intervals between the plurality of machining traces formed along the rotation direction of the table also change randomly, and further, a request for a random machining trace pattern can be satisfied.

  Specifically, the rotation direction random control means is arranged on the optical path of the laser beam from the laser light source to the objective lens, and changes the optical axis of the laser beam irradiated to the workpiece in the rotation direction of the table. The acousto-optic modulation element or electro-optic modulation element (47) and the electro-optic modulation element or electro-optic modulation element are supplied with an electric signal that randomly changes so that the acousto-optic modulation element or electro-optic modulation element is applied to the workpiece The optical axis drive circuit (84) for controlling the acousto-optic modulation element or the electro-optic modulation element may be configured to randomly change the optical axis of the irradiated laser light in the rotation direction of the table. According to this, since the time response of the acousto-optic modulation element or the electro-optic modulation element is high, it is effective when a processing trace with a fine interval is formed on the workpiece by rotating the table at a high speed.

  In addition, the rotation direction random control means supplies an actuator for driving the objective lens to change the optical axis of the laser beam irradiated to the workpiece in the rotation direction of the table, and an electric signal that randomly changes to the actuator. Then, the objective lens may be configured with an optical axis driving circuit that controls the actuator so that the optical axis of the laser light irradiated onto the workpiece is randomly changed in the rotation direction of the table. In this case, since the actuator and the optical axis drive circuit for driving the objective lens in the rotation direction are configured relatively simply, the laser processing apparatus can be configured relatively inexpensively and simply.

  Further, the rotation direction random control means is arranged on the optical path of the laser light from the laser light source to the objective lens, reflects the laser light from the laser light source and guides it to the objective lens, and drives the mirror to be processed. An actuator for changing the optical axis of the laser beam irradiated to the object in the rotation direction of the table, and an optical axis of the laser beam irradiated to the workpiece by the mirror by supplying an electric signal that randomly changes to the actuator May be configured with an optical axis drive circuit that controls the actuator so that the angle is changed randomly in the rotation direction of the table. Also in this case, since the mirror, the actuator, and the optical axis drive circuit are configured relatively simply, the laser processing apparatus can be configured relatively inexpensively and simply.

Another feature of the present invention is a random control means for controlling the formation of a plurality of machining traces such that the intervals between the plurality of machining traces formed along the rotation direction of the table change randomly. Rotation speed random control means (50, 61) for changing the rotation speed of the table rotated by the rotation means at random by electrically controlling the rotation means is provided. Also by this, the intervals between the plurality of machining traces formed along the rotation direction of the table also change randomly, and further, a request for a random machining trace pattern can be satisfied. Also in this case, since the rotation means provided in the laser processing apparatus is only electrically controlled, the laser processing apparatus can be configured inexpensively and easily.

Another feature of the present invention is a random control means for controlling the formation of a plurality of machining traces such that the intervals between the plurality of machining traces formed along the rotation direction of the table change randomly. There is provided pulse interval random control means (50, 72, 72a) for randomly changing the pulse interval in the pulse train drive signal generated by the laser light source driving means . Also by this, the intervals between the plurality of machining traces formed along the rotation direction of the table also change randomly, and further, a request for a random machining trace pattern can be satisfied. Also in this case, since the pulse interval random control means merely changes the pulse interval in the pulse train-like drive signal generated by the laser light source driving means, the laser processing apparatus can be configured inexpensively and easily. In addition, according to this, changing the pulse interval in the pulse train drive signal at random is synchronized with the formation of a plurality of machining traces, so the machining trace interval can be changed randomly at the same time as the formation of the machining traces. It is also effective when forming traces of fine intervals on a workpiece.

Another feature of the present invention is a random control means for controlling the formation of a plurality of machining traces so that the sizes of the plurality of machining traces to be formed are randomly changed . The pulse level random control means (50, 72, 72a) for randomly changing the pulse level in the generated pulse train drive signal is provided. According to this, the size of a plurality of processing traces to be formed also changes randomly, and further, a request for a random processing trace pattern can be satisfied. Also in this case, since the pulse level random control means only changes the pulse level in the pulse train drive signal generated by the laser light source driving means at random, the laser processing apparatus can be configured inexpensively and easily. Also, according to this, changing the pulse level in the pulse train drive signal at random is synchronized with the formation of multiple machining traces, so the size of the machining traces changes randomly simultaneously with the formation of the machining traces. It is also effective when forming traces of fine intervals on a workpiece.

  Furthermore, in carrying out the present invention, the present invention is not limited to the invention of the laser processing apparatus, but can also be implemented as an invention of a laser processing method.

1 is a system configuration diagram of a laser processing apparatus according to an embodiment of the present invention. It is a detailed block diagram of the optical axis drive circuit of FIG. It is a flowchart which shows the process preparation program performed by the controller of FIG. It is a flowchart which shows the detail of the random data generation routine of FIG. It is a table | surface showing the table used in order to derive | lead-out the conversion value which changes between -1 to +1 from 4-digit random data. It is a flowchart which shows the detail of the pulse control data generation routine of FIG. It is a flowchart which shows the process control program performed by the controller of FIG. It is a flowchart which shows the spindle motor control data generation program performed by the controller of FIG. It is a flowchart which shows the feed motor control data generation program performed by the controller of FIG. It is a system block diagram of the laser processing apparatus which concerns on the modification of the said embodiment. (A) is a figure which shows the formation state of the process trace by the conventional apparatus, (B) is a figure which shows the formation state of the process trace (pit) by this invention.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic system configuration diagram of a laser processing apparatus according to an embodiment. This laser processing apparatus has a table 21 as a support member for setting and fixing and supporting a flat plate-shaped workpiece OB, and processing for laser processing the workpiece OB by irradiating a laser beam toward the workpiece OB. And a head 30. The processing object OB is used as an LED substrate by forming innumerable nano-sized ultra-fine pits on the surface by the laser light emitted from the processing head 30. The table 21 is formed in a disk shape and is driven by a spindle motor 22 and a feed motor 23. The processing head 30 is fixed by a head support frame (not shown) fixed to the apparatus main body.

The spindle motor 22 functions as a rotating means of the present invention, and the table 21 is rotationally driven through the rotation shaft 22b by the rotation. The spindle motor 22 incorporates an encoder 22a that detects the rotation of the motor 22, that is, the table 21, and outputs a rotation signal representing the rotation. The rotation signal is alternately switched between an index signal Index generated every time the rotation position of the table 21 comes to one reference rotation position and a high level and a low level each time the table 21 rotates by a predetermined minute angle. It consists of pulse train signals Φ _A and Φ _B. The index signal Index is used to detect the reference rotation position of the table 21. The pulse train signals Φ _A and Φ _B are signals that are used to control the rotational speed of the table 21 and are out of phase with each other by π / 2 to identify the rotational direction.

The index signal Index is supplied to the controller 50, and the pulse train signals Φ _A and Φ _B are supplied to the spindle motor control circuit 61. The spindle motor control circuit 61 starts operation in response to a rotation start instruction from the controller 50, calculates the rotation speed of the spindle motor 22 based on the number of pulses per unit time of the pulse train signals ΦA and ΦB output from the encoder 22a, and calculates The rotation of the spindle motor 22 is controlled so that the rotation speed becomes equal to the rotation speed instructed by the controller 50. The rotational speed instructed by the controller 50 is a speed at which the rotational linear speed of the laser beam with respect to the workpiece OB becomes substantially constant, but it slightly fluctuates randomly with time. The rotational speed that slightly fluctuates randomly is supplied from the controller 50 by processing of a spindle motor control data generation program, which will be described later, executed by the controller 50.

  The feed motor 23 rotates the screw rod 24 to drive the table 21 in the radial direction. The screw rod 24 is connected to one end of the screw rod 24 so as to rotate integrally with the rotation shaft of the feed motor 23, and is screwed to a nut (not shown) fixed to the support member 25 at the other end. The support member 25 fixedly supports the spindle motor 22 and is only allowed to move in the radial direction of the table 21. Therefore, when the feed motor 23 rotates, the spindle motor 22, the table 21, and the support member 25 are displaced in the radial direction of the table 21 by the feed screw mechanism 20 including the screw rod 24 and the nut. The movement direction of the table 21 is set so that a straight line representing the movement locus of the rotation center of the table 21 passes through the irradiation position of the processing head 30. These feed motor 23, screw rod 24, and support portion 25 correspond to the radial movement means of the present invention.

Also incorporated in the feed motor 23 is an encoder 23a that detects the rotation of the feed motor 23 and outputs the same pulse train signals Φ _A and Φ _B as the encoder 22a. The pulse train signals Φ _A and Φ _B output from the encoder 23 a are output to the feed motor control circuit 62 and the radius value detection circuit 63. The radius value detection circuit 63 counts up or counts down the number of pulses of the pulse train signals Φ _A and Φ _B from the encoder 23a according to the rotation direction of the feed motor 23, and the laser beam is irradiated from the count value of the table 21. A radius value r representing the radial feed position (ie, radial position) is detected, and a signal representing the radius value r is output to the controller 50. The initial setting of the count value in the radius value detection circuit 63 is performed by an instruction from the controller 50 when the power is turned on.

That is, the controller 50 instructs the feed motor control circuit 62 to move the support member 25 to the initial position and the radius value detection circuit 63 when the power is turned on. In response to this instruction, the feed motor control circuit 62 rotates the feed motor 23 to move the support member 25 to the initial position. This initial position is a drive limit position of the support member 25 driven by the feed motor 23. The radius value detection circuit 63 continues to input the pulse train signals Φ _A and Φ _B from the encoder 23a while the support member 25 is moving. When the support member 25 reaches the initial position and the rotation of the feed motor 23 stops, the radius value detection circuit 63 detects the stop of the input of the pulse train signals Φ _A and Φ _B from the encoder 23a, and sets the count value to “0”. To "". At this time, the radius value detection circuit 63 outputs a signal for stopping the output to the feed motor control circuit 62, whereby the feed motor control circuit 62 stops outputting the drive signal to the feed motor 23. Thereafter, when the feed motor 23 is driven, the radius value detection circuit 63 counts up or counts down the number of pulses of the pulse train signals Φ _A and Φ _B according to the rotation direction of the feed motor 23, and the count value The radius value r representing the feed position in the radial direction of the table 21 is calculated based on the above, and the signal representing the radius value r is continuously output to the feed motor control circuit 62 and the controller 50.

  The feed motor control circuit 62 drives and controls the feed motor 23 in accordance with an instruction from the controller 50 to move the irradiation position of the laser beam to a designated radial position of the table 21 or move the table 21 in the radial direction at a designated speed. Or Specifically, the feed motor control circuit 62 uses the radius value r detected by the radius value detection circuit 63 when instructed to move the irradiation position of the laser beam to the radius position designated by the controller 50. The rotation of the feed motor 23 is controlled, and the feed motor 23 is rotated until the detected radius value r becomes equal to the value corresponding to the radius position designated by the controller 50.

When the feed motor control circuit 62 is instructed to move the irradiation position of the laser beam in the radial direction of the table 21 at the moving speed designated by the controller 50, the pulse train signals Φ _A , Φ output from the encoder 23a. The movement speed in the radial direction of the table 21 is calculated from _B, and the rotation of the feed motor 23 is controlled so that the calculated movement speed becomes equal to the movement speed designated by the controller 50. The moving speed instructed by the controller 50 is a speed that changes by a substantially constant amount in the radial direction while the laser beam makes one rotation of the workpiece OB, but slightly fluctuates randomly as time passes. The moving speed that varies slightly at random is supplied from the controller 50 by processing of a feed motor control data generation program, which will be described later, executed by the controller 50.

  Next, the processing head 30 will be described. The processing head 30 includes a laser light source 31 and is configured to irradiate laser light emitted from the laser light source 31 toward the processing object OB and to receive the reflected light. The processing head 30 includes a laser light source 31, a collimating lens 32, a polarizing beam splitter 33, a quarter wavelength plate 34, an objective lens 35, a condensing lens 36, a cylindrical lens 37, a four-divided photo detector 38, a focus actuator 39, and the like. Yes. The laser light emitted from the laser light source 31 passes through the collimating lens 32, the polarizing beam splitter 33, the quarter wavelength plate 34, and the objective lens 35, and is condensed on the surface of the processing object OB. Further, the laser beam condensed on the surface of the processing object OB is reflected on the surface of the processing object OB. The reflected light reflected from the surface of the workpiece OB passes through the objective lens 35 and the quarter wavelength plate 34, enters the polarization beam splitter 33, is reflected by the polarization beam splitter 33, and enters the condenser lens 36. . The condensing lens 36 condenses the light reflected by the polarization beam splitter 33 on a four-divided photo detector 38 via a cylindrical lens 37.

  The processing head 30 also includes a photodetector 42 that receives partially reflected light of the laser light from the laser light source 31 by the polarizing beam splitter 33 via the condenser lens 41. The condensing lens 41 condenses the partially reflected light on the photodetector 42. The photodetector 42 detects the amount of received light of the partially reflected light and outputs an electric signal representing the amount of received light. The amount of light received and detected by the photodetector 42 corresponds to the intensity of the laser light emitted from the laser light source 31.

  Further, the machining head 30 also includes an acousto-optic modulation element 43, a tracking actuator 44, and a mirror 45. The acousto-optic modulation element 43 is interposed between the polarization beam splitter 33 and the quarter-wave plate 34, and the optical axis of the laser beam from the polarization beam splitter 33, that is, the laser beam irradiated onto the workpiece OB. Is varied in the radial direction of the table 21. The acousto-optic modulation element 43 is a position on the optical path from the laser light source 31 to the objective lens 34, and varies the optical axis of the laser light applied to the workpiece OB in the radial direction of the table 21. As long as it is a position that can be used, it may be placed at any position. The tracking actuator 44 drives the objective lens 35 in the radial direction of the table 21, and the optical axis of the laser light from the quarter wavelength plate 34, that is, the optical axis of the laser light irradiated on the workpiece OB is set as a table. 21 is varied in the radial direction. The mirror 45 is interposed between the collimating lens 32 and the polarizing beam splitter 33, reflects the laser light from the collimating lens 32 on the reflecting surface and guides it to the polarizing beam splitter 33. The mirror 45 is assembled to the mirror actuator 46. The mirror actuator 46 drives the mirror 45 so that the angle of the reflecting surface of the mirror 45 with respect to the radial direction of the table 21 changes, so that the optical axis of the laser light from the collimating lens 32 to the polarization beam splitter 33, that is, the workpiece. The optical axis of the laser beam irradiated on the OB is varied in the radial direction of the table 21. The mirror 45 is also a position on the optical path from the laser light source 31 to the objective lens 34 and can change the optical axis of the laser light irradiated to the workpiece OB in the radial direction of the table 21. If so, it may be arranged at any position.

  The laser light source 31 is driven by a laser drive circuit 71. When the laser drive circuit 71 starts to operate in response to a command from the controller 50 and receives a pulse train signal from the pulse signal supply circuit 72, the cycle and duty ratio are the same as the input pulse train signal, and the high-side pulse A laser drive signal having a pulse train waveform whose level value is proportional to the level value of the high-side pulse of the input pulse train signal and whose level value of the low-side pulse is a reference value is output to the laser light source 31. The level value of the high-side pulse in the laser drive signal is determined such that the laser light source 31 has a laser beam having an intensity necessary for processing the surface of the workpiece OB by irradiating the surface of the workpiece OB, that is, forming pits. It is a high value which makes it radiate | emit from. Needless to say, this level value can be used for focus servo control described later. The reference value is a small level value that does not process the surface of the processing object OB by laser light irradiation. This laser drive signal is referred to as a laser drive signal set to a processing intensity in order to distinguish it from a laser drive signal set to a non-processing intensity described later. In the present specification, the high-side pulse means a rectangular waveform from when the low level is switched to the high level until the high level is switched to the low level. Further, the low-side pulse means a rectangular waveform having a direction opposite to that of the high-side pulse until switching from the high level to the low level and thereafter switching from the low level to the high level.

  Further, when a DC signal is input from the pulse signal supply circuit 72, the laser drive circuit 71 outputs a continuous laser drive signal at a level set to the non-processing intensity to the laser light source 31. The level value set for the non-working strength is a value similar to the reference value, and the surface of the workpiece OB is processed even when the surface of the workpiece OB is irradiated with laser light. The value is such that the laser light source 31 emits laser light having such intensity that the focus servo control can be performed without any problem. In the following description, this laser drive signal is referred to as a laser drive signal set to a non-processing intensity.

  The laser drive circuit 71 is supplied with an electrical signal representing the amount of laser light received from the photodetector 42, that is, the intensity of the laser light emitted from the laser light source 31. The laser drive circuit 71 feedback-controls the intensity of the laser light source 31 to the processing intensity or the non-processing intensity using an electrical signal representing the intensity of the laser light.

  The pulse signal supply circuit 72 has a built-in memory 72a for storing information relating to the pulse train signal output to the laser drive circuit 71 (hereinafter referred to as pulse train signal information). When pulse train signal information is supplied from the controller 50, the pulse signal supply circuit 72 stores the pulse train signal information supplied to the memory 72a. The pulse signal supply circuit 72 generates a pulse train signal using information stored in the memory 72 a and outputs the pulse train signal to the laser drive circuit 71 when an instruction to start the laser irradiation with the processing intensity is given from the controller 50. The pulse train signal information is the pulse width (duration) of the low-side pulse and high-side pulse and the level value of the high-side pulse. The level value of the low-side pulse is a predetermined fixed reference value. The pulse width of the low-side pulse corresponds to the machining interval in the rotation direction of the pit formed on the workpiece OB, and is almost equal to a fixed value proportional to the designated pit machining interval. fluctuate. The level value of the high side pulse (proportional to the intensity of the laser beam) corresponds to the size of the pit formed on the workpiece OB and is substantially equal to a fixed value proportional to the size of the designated pit. Slightly fluctuates over time. The pulse width of the low-side pulse and the level value of the high-side pulse are supplied from the controller 50 by processing of a later-described pulse control data generation routine executed by the controller 50. The pulse width (duration) of the high-side pulse is set to a predetermined value, and is a fixed value that is initially supplied from the controller 50 and stored in the memory 72a by executing an initial program (not shown). . The pulse signal supply circuit 72 outputs a DC signal to the laser drive circuit 71 when an instruction to start laser irradiation with non-processing intensity is given from the controller 50. These laser drive circuit 71 and pulse signal supply circuit 72 correspond to the laser light source drive means of the present invention.

  Next, laser beam focus servo will be described. The reflected light of the laser beam from the surface of the object OB is received by the four-divided photodetector 38. The four-divided photodetector 38 is constituted by a four-divided light receiving element composed of four light receiving elements having the same square shape divided by dividing lines, and receives light incident on the light receiving areas A, B, C, and D arranged in the clockwise direction. A detection signal having a magnitude proportional to the intensity is output as a light reception signal (a, b, c, d). The quadrant photodetector 38 is fixed so that the reflected light is collected at the center where the four light receiving elements are arranged.

  The received light signals (a, b, c, d) output from the quadrant photodetector 38 are input to the HF signal amplifier circuit 73. The HF signal amplifying circuit 73 amplifies the received light signals (a, b, c, d) and outputs them to the focus error signal generating circuit 74. The focus error signal generation circuit 74 generates a focus error signal by calculation using the amplified light reception signals (a ′, b ′, c ′, d ′). In this embodiment, since the focus servo control by the astigmatism method is used, the calculation of (a ′ + c ′) − (b ′ + d ′) is performed, and the calculation result is used as a focus error signal, and the focus servo circuit 75 Output to. The focus error signal (a ′ + c ′) − (b ′ + d ′) represents the amount of deviation of the focal position of the laser beam from the surface of the workpiece OB.

  The focus servo circuit 75 is operation-controlled by the controller 50, generates a focus servo signal based on the focus error signal, and outputs the focus servo signal to the drive circuit 76. The drive circuit 76 drives and controls the focus actuator 39 in accordance with the focus servo signal to displace the objective lens 35 in the optical axis direction of the laser light. In this case, by generating a focus servo signal so that the value of the focus error signal (a ′ + c ′) − (b ′ + d ′) is always a constant value (for example, zero), the surface of the object OB is processed. The laser beam can be continuously collected.

  Optical axis drive circuits 81, 82, and 83 are connected to the acousto-optic modulation element 43, the tracking actuator 44, and the mirror 45, respectively. As shown in FIG. 2, the optical axis drive circuit 81 includes three sine wave oscillators 81a, 81b, 81c and a mixing circuit 81d. The sine wave oscillators 81a, 81b, 81c start operating in response to an operation start command from the controller 50, and each has a sine wave having an amplitude proportional to the product of the change rate Ra1 and the radial machining interval ΔPt supplied from the controller 50. Each signal is generated. The frequencies of these sine wave signals are different from each other as shown in the figure, and their ratio is set so as not to be an integer ratio, for example, about 10 MHz to 400 MHz. The amplitudes of these sine wave signals may be the same or different. The mixing circuit 81d outputs a drive signal obtained by adding and mixing sine wave signals from the sine wave oscillators 81a, 81b, and 81c. Thereby, as shown in the figure, the optical axis drive circuit 81 randomly changes its instantaneous value over time, and has a waveform signal having a maximum amplitude proportional to the product of the change rate Ra1 and the radial machining interval ΔPt ( Drive signal) is supplied to the acousto-optic modulation element 43, and the acousto-optic modulation element 43 sets the optical axis of the laser beam in the radial direction of the table 21 by an amount corresponding to the product of the change rate Ra1 and the machining interval ΔPt in the radial direction. Change randomly.

  The optical axis drive circuits 82 and 83 are also configured in the same manner as the optical axis drive circuit 81, and supply drive signals whose instantaneous values randomly change with time to the tracking actuator 44 and the mirror actuator 46, respectively. However, the optical axis driving circuits 82 and 83 are supplied from the controller 50 with the product of the change rate Ra2 and the radial machining interval ΔPt and the product of the change rate Ra3 and the radial machining interval ΔPt, respectively. 83 respectively outputs drive signals having amplitudes proportional to the product of the change rate Ra2 and the radial machining interval ΔPt and the product of the change rate Ra3 and the radial machining interval ΔPt. The tracking actuator 44 drives the condenser lens 36 in the tracking direction, that is, the radial direction of the table 21 in accordance with the drive signal. Accordingly, the objective lens 35 also randomly changes the optical axis of the laser light in the radial direction of the table 21 by an amount corresponding to the product of the change rate Ra2 and the processing interval ΔPt in the radial direction. The mirror actuator 46 drives the mirror 45 so as to change the angle of the reflecting surface of the mirror 45 in the radial direction of the table 21 in accordance with the drive signal. Accordingly, the mirror 45 also randomly changes the optical axis of the laser light in the radial direction of the table 21 by an amount corresponding to the product of the change rate Ra3 and the processing interval ΔPt in the radial direction. However, since the tracking actuator 44 and the mirror actuator 46 do not have responsiveness to a higher frequency than the acousto-optic modulation element 43, the sine output from the sine wave oscillators in the optical axis drive circuits 82 and 83. The frequency of the wave signal is lower than the frequency of the sine wave signal output from the sine wave oscillator in the optical axis drive circuit 81, and is, for example, about 0.1 KHz to 50 KHz.

  Note that a signal generator that generates different waveforms such as a triangular waveform and a sawtooth waveform may be used in place of the sine wave oscillators constituting the optical axis driving circuits 81, 82, and 83. Further, regarding the number of sine wave oscillators (or other signal generators that generate other waveforms), if the instantaneous values of the signals generated from the optical axis drive circuits 81, 82, and 83 change with time, other than three. But you can. Furthermore, as a waveform signal output from the sine wave oscillator (or a signal generator that generates another waveform), a waveform signal whose frequency (that is, period) and / or amplitude changes randomly may be adopted.

  The controller 50 is an electronic control device including a plurality of microcomputers including CPUs, ROMs, RAMs, storage devices such as hard disks and nonvolatile memories, input / output interfaces, and the like. The storage device stores various programs and routines to be described later. Connected to the controller 50 are an input device 51 for an operator to instruct various parameters, processing, and the like, and a display device 52 for visually informing the operator of inspection results, operating conditions, and the like. .

  When performing laser processing, the operator uses the input device 51 to instruct the controller 50 to start execution of the processing preparation program. The machining preparation program is shown in the flowchart of FIG. 3, and its execution is started in step S10. After starting the execution of the machining preparation program, the controller 50 displays the machining conditions (start radius value Rf, end radius value Re, rotation linear velocity F, rotation interval W in the rotation direction, radial direction) in step S11. The operator is prompted to input the processing interval ΔPt, the basic level value Pw of the high-side pulse, and the maximum change rate R1, Rr, R3, R4), and the processing conditions input by the operator using the input device 51 are input. Remember. Instead of the input from the input device 51, a value stored in the memory of the controller 50 may be used.

  The start radius value Rf is the distance from the rotation center of the table 21 of the laser spot when laser processing is started. The end radius value Re is the distance of the laser spot from the rotation center of the table 21 when the laser processing is ended. The rotation linear velocity F is a speed at which the laser spot (irradiation position) moves in the circumferential direction on the surface of the workpiece OB in laser processing. The processing interval W in the rotation direction is an interval at which pits are formed in the rotation direction (circumferential direction) in laser processing, that is, an interval in the rotation direction between two pit centers adjacent to the rotation direction. The processing interval ΔPt in the radial direction is an interval for forming pits in the radial direction in laser processing, that is, the amount of movement of the laser spot in the radial direction when the laser spot moves on the surface of the workpiece OB by one round. The basic level value Pw of the high-side pulse represents the basic level of the high-side pulse, and proportionally controls the intensity of the laser beam, that is, the size of the laser processing trace. The maximum change rate R1 is the maximum change rate of the rotational linear velocity F. The maximum change rate Rr is the maximum change rate of the processing interval ΔPt in the radial direction. The maximum change rate R3 is the maximum change rate of the pulse width (low level duration) of the low-side pulse. The maximum change rate R4 is the maximum change rate of the level value of the high-side pulse. Note that these maximum change ratios R1, Rr, R3, and R4 are values of, for example, several percent to several tens percent.

After the process of step S11, the controller 50 uses the input rotational linear velocity F and the processing interval W in the rotational direction and the pulse width Wh of the high-side pulse, which is a fixed value, in step S12. To calculate the basic pulse width Wd of the low-side pulse. The basic pulse width Wd of the low-side pulse is the basic low-level duration of the pulse train signal output from the pulse signal supply circuit 72, that is, the drive pulse train supplied from the laser drive circuit 71 to the laser light source 31. Represents the basic duration of the low level of the signal.
(Equation 1)
Wd = (W / F) -Wh

  Next, in step S13, the controller 50 uses the maximum change rate Rr with respect to the input radial processing interval ΔPt, by the acoustooptic modulator 43, the tracking actuator 44, the mirror actuator 46, and the feed motor control circuit 62. The ratios Ra1, Ra2, Ra3, R2 of the random change in the radial direction of the optical axis of the laser light are calculated. In this case, the ratios Ra1, Ra2, Ra3, and R2 may be obtained by dividing the maximum change ratio Rr into four equal parts, or may be ratios set in advance. In step S14, the controller 50 supplies values obtained by multiplying the calculated ratios Ra1, Ra2, Ra3 by the radial machining interval ΔPt to the optical axis drive circuits 81, 82, 83, respectively. The optical axis driving circuits 81, 82, 83 store the supplied values obtained by multiplying the ratios Ra 1, Ra 2, Ra 3 by the radial machining interval ΔPt, and the operation start instruction from the controller 50. Wait for.

After the processing in step S14, the controller 50 executes random data generation processing in step S15, thereby changing four types that change randomly in units of “0.01” between “−1” and “+1”. Random data a (n), b (n), c (n), and d (n) are generated. In this random data generation process, first, the random data generation routine of FIG. 4 is executed. The execution of this random data generation routine is started in step S100, and the controller 50 initializes the variable n to “1” in step S101, and the variable n is determined in advance by the processing in steps S105 and S106. The cyclic processing consisting of steps S102 to S106 is repeatedly executed while increasing the variable n by “1” until the maximum value n _max is reached. Then, when the variable n reaches the maximum value n _max , the execution of the random data generation routine is terminated in step S107.

In step S102, the controller 50 sets a four-digit random number Ran (n) in decimal notation. In setting this random number Ran (n), it may be calculated a random number Ran (n) for each processing of step S102 by executing a previously prepared random program, according to pre-n _max pieces of decimal 4 A random number of digits may be stored in the memory, and the random number specified by the variable n may be set as the random number Ran (n). The value n _max is a predetermined value indicating the number of set random numbers Ran (n). In step S103, it is determined whether the set random number Ran (n) is equal to or less than “9848”. The reason for executing this determination processing is that “201” random numbers in units of “0.01” between “−1” and “+1” will be described later for the values “9849” to “9999”. This is because they cannot be equally allocated to the conversion table. When the set random number Ran (n) is larger than “9848”, it is determined as “No” in step S103, and the processes in steps S102 and S103 are executed again. If the set random number Ran (n) is “9848” or less, “Yes” is determined in step S103, and the process proceeds to step S104.

  In step S104, the set 4-digit decimal number Ran (n) is expressed in units of “0.01” from “−1” to “+1” using the conversion table shown in the table of FIG. Is converted to one of the data that changes. The conversion table equalizes the data that increases by “0.01” from “−1” to “+1” with respect to the 4-digit decimal number from “0000” to “9848” that the random number Ran (n) can take. Assigned to. In the conversion process of step S104, in the table of FIG. 5, the conversion value at the right end of the row to which the 4-digit random number Ran (n) set by the process of step S102 belongs is set as random data a (n). Is done. Specifically, for example, if the set random number Ran (n) is any value such as “0000” or “0201” in the first row in the table, the random data a (n) The value “0.00” is set. If the set random number Ran (n) is any value such as “0001” and “0202” in the second row in the table, the value “0.01” is assumed as random data a (n). Is set.

By executing this random data generation routine, random data a (1) to a (n _max ) in which numerical values in units of “0.01” from “−1” to “+1” are randomly selected are set, and the controller It is stored in 50 memories. Returning again to the description of the random data generation process in step S15 in FIG. 3, the controller 50 also performs random data similar to that in FIG. 5 described above for random data b (n), c (n), and d (n). The generation routine is executed, and random data b (1) to b (n _max ), c (1) to c (1) that change randomly from “−1” to “+1” in units of “0.01”. n _max ), d (1) to d (n _max ) are generated and stored in the memory in the controller 50. In these cases, the maximum value n _max representing the number of random data b (n), c (n), and d (n) is different from the random data a (n) even if it is the same value as the random data a (n). There may be. For random data b (n), c (n), and d (n), instead of executing a random data generation routine similar to FIG. 5, random data a (1) to a (n _max ), A (p) to a (n _max ), a (1) to a (p−1) in random data b (1) to b (n _max ), c (1) to c (n _max ) , D (1) to d (n _max ). Note that p is an integer value of any one of “2” to “n _max ”, and is different depending on b (n), c (n), and d (n). Further, in place of the random data generation process in step S15 in FIG. 3, random data a (1) to a (n _max ) that change randomly between “−1” and “+1” in units of “0.01”. ), B (1) to b (n _max ), c (1) to c (n _max ), and d (1) to d (n _max ) may be stored in the memory in the controller 50 in advance. .

After the processing in step S15, the controller 50 corrects the low-side pulse that randomly changes with respect to the calculated basic pulse width Wd of the low-side pulse by executing the pulse control data generation processing in step S16. A correction level value Pw (n) of the high-side pulse that randomly changes with respect to the pulse width Wd (n) and the basic level value Pw of the input high-side pulse is generated. In this pulse control data generation process, the pulse control data generation routine of FIG. 6 is executed. The execution of this pulse control data generation routine is started in step S200. The controller 50 initializes the variable n to “1” in step S201, and the variable n is determined in advance by the processing in steps S205 and S206. The cyclic process consisting of steps S202 to S206 is repeatedly executed while increasing the variable n by “1” until the maximum value n _max is reached. Then, when the variable n reaches the maximum value n _max , the execution of this pulse control data generation routine is terminated in step S207.

In step S202, by using the calculated basic pulse width Wd of the low-side pulse, the calculated random data c (n), and the input maximum change rate R3, A correction pulse width Wd (n) of a low-side pulse that randomly changes is calculated.
(Equation 2)
Wd (n) = {1 + R3 · c (n)} · Wd

In step S203, by using the basic level value Pw of the input high-side pulse, the calculated random data d (n), and the input maximum change ratio R4, A correction level value Pw (n) of a randomly changing high side pulse is calculated.
(Equation 3)
Pw (n) = {1 + R4 · d (n)} · Pw

In step S204, the calculated correction pulse width Wd (n) of the low-side pulse and the correction level value Pw (n) of the high-side pulse are output to the pulse signal supply circuit 72. The pulse signal supply circuit 72 stores the low pulse correction pulse width Wd (n) and the high pulse correction level value Pw (n) output in the memory 72a. The correction pulse widths Wd (1), Wd (2),..., For each of n _max low-side pulses that change randomly when the pulse control data generation routine is completed by repeating the steps S202 to S204. wd (n _max) and the high-side pulse correction level value Pw (1), Pw (2 ) ··· Pw (n max) is stored in the memory 72a.

  Returning to the description of FIG. 3 again, after the completion of the pulse control data generation process in step S16, the controller 50 ends the execution of the machining preparation program in step S17. This machining preparation program is a program to be executed when forming a new type of pits on the workpiece OB, and needs to be executed when forming the same pits on a plurality of workpieces OB. There is no.

Next, laser processing will be described. The operator sets the workpiece OB on the table 21 and uses the input device 51 to instruct the controller 50 to start executing the laser machining control program. The execution of the laser processing control program is started in step S300 in FIG. 7, and the controller 50 outputs a rotation start command to the spindle motor control circuit 61 in step S301. When outputting the rotation start command, the controller 50 inputs the radius value r detected by the radius value detection circuit 63, and using this radius value r, the rotational linear velocity of the laser spot is the radius at which the laser spot is located. Regardless of the position, the rotational speed of the spindle motor 22 is always calculated so that the specified rotational linear speed F is obtained, and the calculated rotational speed is output to the spindle motor control circuit 61. The spindle motor control circuit 61 calculates the rotation speed of the spindle motor 22 by using the pulse train signals Φ _A and Φ _B from the encoder 22 a, and the spindle so that the calculated rotation speed becomes equal to the rotation speed input from the controller 50. The rotation control of the motor 22 is started. After outputting the rotation start instruction, the controller 50 repeatedly calculates the rotation speed of the spindle motor 22 according to the radius value r by executing a later-described spindle motor control data generation program that is different from the machining control program. Each time, the calculated rotation speed is output to the spindle motor control circuit 61.

  Subsequently, the controller 50 outputs a movement command to the start radius position to the feed motor control circuit 62 in step S302. The start radius position is a radius position corresponding to the start radius value Rf input in advance by the operator. In response to this movement command, the feed motor control circuit 62 rotates the feed motor 23 and starts moving the table 21 in a direction in which the irradiation position of the laser light approaches the radial position corresponding to the start radius value Rf. In step S303, the controller 50 inputs the radius value r from the radius value detection circuit 63, and the laser beam irradiation position is the start radius value Rf until the input radius value r becomes equal to the start radius value Rf. The determination process is continued until the radius position corresponding to is reached. Then, when the table 21 moves and the radius value r becomes equal to the start radius value Rf, the controller 50 determines “Yes” in step S303, and instructs the laser drive circuit 71 to start driving in step S304. And a DC signal output start command to the pulse signal supply circuit 72. As a result, the pulse signal supply circuit 72 outputs a DC signal to the laser drive circuit 71, and the laser drive circuit 71 outputs a continuous laser drive signal set to the non-processing intensity to the laser light source 31. In this case, the laser drive circuit 71 feedback-controls the laser drive signal using an electrical signal representing the amount of light received from the photodetector 42. The laser light source 31 is driven by the laser drive signal output from the laser drive circuit 71 and emits non-processing laser light. As a result, a light spot of non-machining laser light is formed on the surface of the workpiece OB, and the reflected light of this light spot is detected by the four-divided photodetector 38. The processing object OB is not processed by the irradiation of the non-processing laser beam.

  After the processing in step S304, the controller 50 outputs a focus servo start command to the focus servo circuit 75 in step S305. Thereby, a focus actuator drive circuit (not shown) drives the focus actuator 39, and the focus servo circuit 75 generates a focus servo signal using the focus error signal from the focus error signal generation circuit 74, and an S-character detection circuit (not shown). At the timing when an S-shaped waveform is formed in the focus error signal, drive control of the focus actuator 39 is started via the drive circuit 76 in accordance with the focus servo signal, and focus servo control is started. That is, the focus servo is started at the timing when the focal position of the laser beam moves in the optical axis direction of the laser beam and the focal position of the laser beam coincides with the surface of the workpiece OB. Then, the objective lens 35 is driven and controlled in the optical axis direction of the laser light so that the focal position of the laser light coincides with the surface of the workpiece OB.

  Next, in step S306, the controller 50 instructs the optical axis drive circuits 81, 82, 83 to start operation. In response to this operation start instruction, the optical axis drive circuits 81, 82, 83 multiply the change rates Ra1, Ra2, Ra3 supplied from the controller 50 by the execution of the machining preparation program described above by the machining intervals ΔPt in the radial direction. The optical axis drive signal whose amplitude is proportional to the measured value and whose instantaneous value changes at random is started to be supplied to the acousto-optic modulator 43, the tracking actuator 44 and the mirror actuator 46, respectively. As a result, the acoustooptic modulator 43, tracking actuator 44, and mirror actuator 46 multiply the optical axis of the laser beam in the radial direction of the table 21 and the change ratios Ra1, Ra2, Ra3 by the machining interval ΔPt in the radial direction. Start changing the amount of each value randomly.

  Next, in step S307, the controller 50 reads a rotation signal indicating the rotation of the spindle motor 22 from the encoder 22a, and determines whether or not the index signal Index has been input. The index signal Index is a signal output from the encoder 22a every time the rotation position of the table 21 reaches the reference rotation position, that is, a signal output at the reference rotation position only once during one rotation of the table 21. . Until the index signal Index is input, the controller 50 continues to determine “No” in step S307 and repeats the determination process. When the index signal Index is input, the controller 50 determines “Yes” in step S307 and executes the process of step S308.

In step S308, the controller 50 outputs a pulse train signal output start command to the pulse signal supply circuit 72 and instructs the laser drive circuit 71 to start operation. When the pulse signal supply circuit 72 receives the pulse train signal output start command output from the controller 50, the pulse signal supply circuit 72 outputs a pulse train signal to the laser drive circuit 71 in accordance with the pulse train signal information stored in the memory 72a. In this case, as the level value of the pulse width and the high-side pulse low side pulse is a pulse train signal information, by executing the pulse control data generating routine described above, n _max that is supplied from the controller 50 is stored in the memory 72a The correction pulse widths Wd (1), Wd (2)... Wd (n _max ) of the randomly changing low side pulse and the correction level values Pw (1), Pw (2) of the high side pulse. • Pw (n _max ) is used. As the pulse width (duration) Wh of the high-side pulse that is pulse train signal information, a fixed value that is initially supplied from the controller 50 and stored in the memory 72a by execution of an initial program (not shown) is used. . The level value of the low-side pulse is a predetermined fixed reference value.

The generation of the pulse train signal using the pulse train signal information will be described in detail. The pulse signal supply circuit 72 includes the correction pulse widths Wd (1), Wd (2),. ..Wd (n _max ) and correction level values Pw (1), Pw (2)... Pw (n _max ) of the high side pulse are read out one by one, and the pulse width of the low side pulse and the high side pulse And the pulse width Wh of the high-side pulse stored in the memory 72a is read out. The pulse signal supply circuit 72 is at a level defined by a fixed reference value and has a pulse width of the set low-side pulse and a level value of the set high-side pulse. One pulse signal composed of a high-side pulse having a prescribed level and having the pulse width Wh of the read high-side pulse is sequentially generated and sequentially output to the laser driving circuit 71. Therefore, the pulse train signal supplied to the laser drive circuit 71 has the pulse width of the low-side pulse and the level value of the high-side pulse sequentially and randomly changed. In this case, strictly speaking, the pulse width of the low-side pulse and the level value of the high-side pulse of the pulse train signal have periodicity of n _max pieces, but if the value n _max is sufficiently large, In the predetermined laser processed region, the pulse width of the low-side pulse and the level value of the high-side pulse can be considered to change sufficiently randomly.

The laser drive circuit 71 receives the pulse train signal from the pulse signal supply circuit 72, so that the period and duty ratio are the same as the pulse train signal inputted, and the level value of the high pulse is the high side pulse of the inputted pulse train signal. The laser light source 31 starts to output a laser drive signal having a pulse train waveform that is proportional to the level value and whose level value of the low-side pulse is a reference value. In this case as well, the laser drive circuit 71 feedback-controls the laser drive signal using an electrical signal representing the amount of light received from the photodetector 42. Accordingly, the laser light source 31 emits a processing laser beam in the form of a pulse train in which the pulse width of the low-side pulse and the level value of the high-side pulse are sequentially changed at random. In this case, strictly speaking, the pulse width of the low-side pulse and the level value of the high-side pulse of the pulse train signal have periodicity of n _max pieces, but as described above, the value n _max is sufficient. If a large value is taken, it can be considered that the pulse width of the low-side pulse and the level value of the high-side pulse change sufficiently randomly in a predetermined region processed by laser processing.

  The processing laser light emitted from the laser light source 31 passes through the collimating lens 32, the mirror 45, the polarizing beam splitter 33, the acoustooptic modulator 43, the quarter wavelength plate 34, and the objective lens 35, and the surface of the processing object OB. To collect light. Therefore, the processing object OB starts to be processed by the processing laser beam. In this case, the acousto-optic modulator 43, the tracking actuator 44, and the mirror actuator 46 change the optical axis of the processing laser light at random in the radial direction of the table 21, so that the processing target by the processing laser light is used. The processing position of the object OB also changes randomly in the radial direction of the table 21. Also in this case, the reflected light of the processing laser light reflected on the surface of the processing object OB passes through the objective lens 35, the quarter wavelength plate 34, the polarization beam splitter 33, the condensing lens 36, and the cylindrical lens 37. Then, the light enters the quadrant photodetector 38. The HF signal amplification circuit 73, the focus error signal generation circuit 74, the focus servo circuit 75, the drive circuit 76, and the focus actuator 39 use the reflected light of the processing laser light incident on the four-divided photodetector 38, and the objective lens 35 is controlled in focus.

  After the process of step S308, the controller 50 outputs a command to start radial movement to the feed motor control circuit 62 in step S309. Thereby, the feed motor 23 is driven by the feed motor control circuit 62, and the table 21 starts to move in the radial direction. After outputting the radial direction movement start instruction, the controller 50 calculates the rotational speed of the feed motor 23 according to the radius value r by executing a feed motor control data generation program, which will be described later, which is different from the machining control program. The calculated rotation speed is output to the spindle motor control circuit 61 each time. Thereby, the irradiation position of the processing laser beam on the processing object OB starts to change in the radial direction of the table 21, and pits start to be formed in the rotation direction and the radial direction of the table 21 on the processing object OB.

  After the processing in step S309, the controller 50 inputs the radius value r detected by the radius value detection circuit 63 in step S310, and determines whether or not the input radius value r is equal to or greater than the end radius value Re. to decide. The end radius value Re is a value input by the operator as the laser processing condition as described above. The process of step S310 is repeated until the radius value r becomes equal to or greater than the end radius value Re. Accordingly, during this time, a pulse train signal is output from the pulse signal supply circuit 72, and laser processing of the workpiece OB is continued.

  Here, a spindle motor control data generation program and a feed motor control data generation program executed by the controller 50 in parallel with the machining control program will be described.

The spindle motor control data generation program is started in step S400 as shown in FIG. After starting the execution, the controller 50 initializes the variable n to “1” in step S401, and waits for the input of the index signal Index from the encoder 22a in step S402. When the index signal Index is input, the controller 50 determines “Yes” in step S402, and inputs a radius value r representing the radius position where the laser spot is located from the radius value detection circuit 63 in step S403. . Then, in step S404, the controller 50 executes the calculation of the following equation 4 using the radius value r and the rotational linear velocity F, so that the rotational linear velocity of the laser spot by the processing laser beam is the input rotational linear velocity. The basic rotational speed Ro of the table 21 is calculated so as to be maintained at F.
(Equation 4)
Ro = F / 2 · π · r

Next, the controller 50, in step S405, the random data a (n) specified by the calculated basic rotational speed Ro and the variable n in the calculated random data a (1) to a (n _max ), Then, using the inputted maximum change rate R1, the corrected rotational speed Ro ′ is calculated by executing the following equation (5).
(Equation 5)
Ro ′ = {1 + R1 · a (n)} · Ro
Then, the controller 50 outputs the calculated corrected rotational speed Ro ′ to the spindle motor control circuit 61 in step S406.

The spindle motor control circuit 61 adjusts the spindle motor 22 so that the rotational speed of the spindle motor 22 calculated using the pulse train signals Φ _A and Φ _B from the encoder 22a is equal to the corrected rotational speed Ro ′ output from the controller 50. 22 is controlled. Therefore, the spindle motor 22 starts to rotate at the corrected rotational speed Ro ′. After the process of step S406, the controller 50 determines whether a laser irradiation stop command (to be described later) has been issued in step S407. If there is no laser irradiation stop command, the controller 50 determines “No” in step S407, and the variable n reaches the end of the random data a (1) to a (n _max ), that is, the value n _max in step S408. Determine if you did. If the variable n has not reached the value n _max , the controller 50 determines “No” in step S408, adds “1” to the variable n in step S409, and returns the program to step S402. In step S402, the controller 50 again waits for the input of the index signal Index from the encoder 22a.

When the index signal Index is input, the controller 50 determines “Yes” in step S402 and executes the processes of steps S403 to S407 described above again. As a result, the corrected rotational speed Ro ′ newly calculated by the calculation of Equation 5 is output to the spindle motor control circuit 61, and the spindle motor 22 starts to rotate at the newly calculated corrected rotational speed Ro ′. As long as there is no laser irradiation stop command and the variable n does not reach the value n _max , the controller 50 continues to determine “No” in steps S407 and S408, while increasing the variable n by “1”, Through the processing in steps S402 to S406, a new corrected rotational speed Ro ′ is output to the spindle motor control circuit 61 based on the new radius value r and random data a (n), and the rotational speed of the spindle motor 22 is corrected and rotated. Control is performed so that the speed Ro ′ is reached.

When the variable n reaches the value n _max , the controller 50 determines “Yes” in step S408, returns the variable n to “1” in step S401, and then performs the processing from step S402 onward. Run. By such processing, every time the irradiation position of the processing laser light is rotated once, the rotation speed of the processing object OB is randomly changed from the basic rotation speed Ro slightly. As a result, every time the irradiation position of the processing laser light is rotated once, the rotational position of the pit formed on the processing object OB by the processing laser light is randomly changed. Also in this case, strictly speaking, the random data a (n) has a periodicity of n _max pieces, but if a sufficiently large value is taken as the value n _max , in a predetermined region processed by laser processing, It can be considered that the rotation direction position of the pit for each rotation formed on the workpiece OB changes sufficiently randomly.

The feed motor control data generation program is started in step S500 as shown in FIG. After starting the execution, the controller 50 initializes the variable m to “1” in step S501, and inputs a radius value r representing the radius position where the laser spot is located from the radius value detection circuit 63 in step S502. . Then, in step S503, the controller 50 performs the following mathematical expression 6 using the processing interval ΔPt, the radius value r, and the rotational linear velocity F, thereby performing one rotation in the radial direction of the laser spot by the processing laser beam. A basic radial direction moving speed Fr of the table 21 is calculated such that the amount of movement per unit is maintained at the input machining interval ΔPt.
(Equation 6)
Fr = ΔPt / (2 · π · r / F)

Next, in step S505, the controller 50 determines the random data b (m (m) specified by the calculated basic radial movement speed Fr and the variable m in the calculated random data b (1) to b (m _max ). ) And the inputted maximum change rate R2, the corrected radial movement speed Fr ′ is calculated by executing the following equation (7).
(Equation 7)
Fr ′ = {1 + R2 · b (m)} · Fr
Then, the controller 50 outputs the calculated corrected radial direction moving speed Fr ′ to the feed motor control circuit 62 in step S505.

The feed motor control circuit 62 calculates the radial movement speed of the table 21 from the pulse train signals Φ _A and Φ _B from the encoder 23a, and the calculated radial movement speed becomes equal to the corrected radial movement speed Fr ′. The rotation of the feed motor 23 is controlled. By controlling the rotation of the feed motor 23, the laser spot of the processing laser light starts to move in the radial direction of the table 21 at the corrected radial movement speed Fr ′. After the process of step S505, the controller 50 determines whether a laser irradiation stop command (to be described later) has been issued in step S506. If there is no laser irradiation stop command, the controller 50 determines “No” in step S506, and the variable m reaches the end of the random data b (1) to b (m _max ), that is, the value m _max in step S507. Determine if you did. If the variable m has not reached the value m _max , the controller 50 determines “No” in step S507, adds “1” to the variable m in step S508, and returns the program to step S502.

Then, the controller 50 executes the processes of steps S502 to S505 described above again. As a result, the corrected radial movement speed Fr ′ newly calculated by the calculation of Equation 7 is output to the feed motor control circuit 62, and the feed motor 23 is set to the newly calculated corrected radial movement speed Fr ′. Start rotating at the corresponding rotation speed. As long as there is no laser irradiation stop command and the variable m does not reach the value m _max , the controller 50 continues to determine “No” in steps S506 and S507, and increases the variable m by “1”. Through the processing in steps S502 to S505, a new corrected radial movement speed Fr ′ is output to the feed motor control circuit 62 based on the new radius value r and the random data b (n), and the rotation speed of the feed motor 23 is determined. The rotation speed is controlled to correspond to the correction radial direction movement speed Fr ′.

When the variable m reaches the value m _max , the controller 50 determines “Yes” in step S507, returns the variable m to “1” in step S501, and then executes the processes in and after step S502 described above. To do. By such processing, the moving speed in the radial direction of the processing laser light changes slightly at random from the basic radial moving speed Fr. As a result, the radial position of the pits formed on the workpiece OB by the machining laser light changes randomly. Again, strictly speaking, although the random data b (m) will have a periodicity of m _max pieces each, taking a sufficiently large value as the value m _max, a predetermined region of laser machining, It can be considered that the radial position of the pit formed on the workpiece OB changes sufficiently randomly.

  Returning to the description of the machining control program in FIG. 7 again, when the radius value r detected by the radius value detection circuit 63 is equal to or greater than the end radius value Re, the controller 50 determines “Yes” in step S310. , Steps S311 to S316 are executed. In step S311, an operation stop command is output to the focus servo circuit 75, and focus servo control by the focus servo circuit 75 is stopped. In step S312, the operation stop command is output to the optical axis drive circuits 81 to 83, and the operation of the optical axis drive circuits 81 to 83 is also stopped. In step S 314, a pulse train signal output stop command is output to the pulse signal supply circuit 72, and a laser beam irradiation stop command is output to the laser drive circuit 71. The output of the laser drive signal by the laser drive circuit 71 is stopped. As a result, the laser light source 31 stops emitting the processing laser light. In step S315, a feed stop command in the radial direction is output to the feed motor control circuit 62, and the feed motor control circuit 62 stops the feed motor 23. In step S316, a rotation stop command is output to the spindle motor control circuit 61, and the spindle motor control circuit 61 stops the rotation of the spindle motor 22. And the controller 50 complete | finishes a laser processing control routine in step S317.

  Further, with the generation of the laser beam irradiation stop command in step S314, the controller 50 determines “Yes” in step S407 also in the spindle motor control data generation program of FIG. 8, and the spindle in step S410. The execution of the motor control data generation program is terminated. Further, the controller 50 determines “Yes” in step S506 in the feed motor control data generation program of FIG. 9 in response to the generation of the laser beam irradiation stop command, and feed motor control data in step S509. Terminates the generation program execution.

  By executing such a machining control program, as shown in FIG. 11B, pit patterns with substantially equal intervals in the rotational direction and the radial direction are formed on the surface of the workpiece OB. However, during the formation of the pits, the acousto-optic modulator 43, the tracking actuator 44, and the mirror 45 randomly change the optical axis of the laser beam for processing in the radial direction by a drive signal output from the optical axis drive circuits 81 to 83. To change. Further, the feed motor control circuit 62 controls the rotational speed of the feed motor 23 based on the corrected radial movement speed Fr ′ generated by the feed motor control data generation program of FIG. Change the position randomly by a small amount. By these random controls, the position of the pits formed on the surface of the workpiece OB changes randomly by a small amount in the radial direction.

  Further, during the formation of the pits, the spindle motor control circuit 61 controls the rotation speed of the spindle motor 22 by the corrected rotation speed Ro ′ generated by the spindle motor control data generation program of FIG. The irradiation position in the rotation direction of the laser beam for use is randomly changed by a small amount. The pulse signal supply circuit 72 outputs a pulse train signal obtained by randomly changing the pulse width of the low-side pulse for each pulse to the laser drive circuit 71, and the laser drive circuit 71 is irradiated on the surface of the workpiece OB. The emission interval of the processing laser beam is changed randomly. By these controls, the positions of the pits formed on the surface of the workpiece OB are randomly changed by a small amount in the rotation direction.

  Further, during the formation of the pits, the pulse signal supply circuit 72 outputs a pulse train signal obtained by randomly changing the level value of the high-side pulse for each pulse to the laser drive circuit 71, and the laser drive circuit 71 The irradiation intensity of the processing laser beam irradiated on the surface of the OB is randomly changed. By this control, the intensity of the processing laser light irradiated on the surface of the workpiece OB changes randomly, and the size of the pits formed on the surface of the workpiece OB changes randomly. By these random controls, as shown in FIG. 11B, the pits formed on the surface of the workpiece OB are not regular, and their rotational direction position (lateral position in the figure), radial position ( The position in the illustrated vertical direction) and the size change randomly.

  In particular, in this embodiment, the acousto-optic modulation element 43 is controlled by a randomly changing drive signal so that the pit position is randomly changed by a small amount in the radial direction, and the pulse train signal output from the pulse signal supply circuit 72 By randomly changing the pulse width of the low-side pulse, the pit position is randomly changed by a small amount in the rotation direction, and the level value of the high-side pulse of the pulse train signal output from the pulse signal supply circuit 72 is randomly The size of the pits was changed randomly by changing it. These random controls are performed by randomly changing the optical axis of the processing laser beam in the radial direction by the tracking actuator 44 and the mirror actuator 46, and by rotating the irradiation position of the processing laser beam by random control of the rotation speed of the spindle motor 22. The time response is higher than the random change in the radial direction of the irradiation position of the processing laser beam by the random change of the laser beam and the random control of the rotation speed of the feed motor 23. Therefore, it is extremely effective for random control when the table 21 is rotated at a high speed to form finely spaced pits on the workpiece OB.

  If the workpiece OB on which the pit pattern is formed in this manner is removed from the table 21, the workpiece OB on which a plurality of pits are randomly formed can be obtained. When forming a pit pattern on a new workpiece OB, the operator sets the new workpiece OB on the table 21 and uses the input device 51 to perform laser machining control on the controller 50. Instructs the start of program execution. Thereby, as described above, a plurality of random pits are formed on the new workpiece OB.

  The embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the object of the present invention.

  For example, in the present embodiment, in order to randomly change the radial position where pits are formed, random change in the radial direction of the optical axis of the processing laser beam by the tracking actuator 44 and the mirror actuator 46 is employed. . However, in addition to these random controls, as shown in FIG. 10, an acousto-optic modulation element 47 for displacing the optical axis of the processing laser beam in the rotational direction, that is, processing on the surface of the processing object OB. An acousto-optic modulation element 47 that displaces the optical axis of the laser light in a direction orthogonal to the case of the acousto-optic modulation element 43 may be provided. In this case, an optical axis drive circuit 84 configured in the same manner as the optical axis drive circuits 81 to 83 of the above embodiment is provided, and a processing laser is supplied to the acousto-optic modulation element 47 by a control signal output from the optical axis drive circuit 84. It is preferable to change the optical axis of light randomly in the rotation direction.

  Other configurations are the same as those in the above embodiment. However, the mirror 45 can be omitted. Even in this modification, the pits formed on the surface of the workpiece OB are not regular, and their rotational direction position (lateral position in the figure), radial position (vertical position in the figure), and size are random. Will be changed. In this modification, the pits formed on the surface of the workpiece OB are randomly changed in the rotation direction by the optical axis drive circuit 84 and the acoustooptic modulator 47, and the random control by the acoustooptic modulator 47 is Since the time response is high, even if the random control of the pulse width of the low-side pulse of the pulse train signal is omitted, it is extremely useful for the random control when the table 21 is rotated at a high speed to form pits with fine intervals on the workpiece OB. It is valid.

  In the above embodiment, in order to randomly change the pits formed on the surface of the workpiece OB in the radial direction, the acoustooptic modulator 43, the tracking actuator 44, and the optical axis driving circuits 81, 82, and 83 are used. Random control of the mirror actuator 46 and random control of the feed motor 23 by the feed motor control circuit 62 are employed. However, in order to randomly change the pits in the radial direction, at least one of these random controls may be adopted, and if necessary, any one to three of these random controls may be used. It may be omitted. Further, if it is not necessary to randomly change the pits in the radial direction, all of these random controls may be omitted. This means that in the above modification, random control using the acousto-optic modulation element 47 by the optical axis drive circuit 84 and random control of the feed motor 23 by the feed motor control circuit 62 are omitted.

  Further, in the above embodiment, in order to randomly change the pits formed on the surface of the workpiece OB in the rotation direction, the spindle motor 22 is randomly controlled by the spindle motor control circuit 61, and the low-side pulse of the pulse train signal. Adopted random control of the pulse width. However, in order to change the pits randomly in the rotation direction, it is sufficient to employ at least one of these random controls, and omit one of these random controls as necessary. Also good. Furthermore, if it is not necessary to change the pits randomly in the rotation direction, all of these random controls may be omitted.

  Further, in the above embodiment, random control of the level value of the high-side pulse of the pulse train signal is employed in order to randomly change the size of the pit formed on the surface of the workpiece OB. However, this random control may be omitted if it is not necessary to randomly change the size of the pits.

  Further, in the above embodiment and the modified example, the correction rotational speed Ro ′ is output to the spindle motor control circuit 61 to change the rotational speed of the spindle motor 22 at random, thereby forming on the surface of the workpiece OB. The interval in the pit rotation direction was randomly changed for each rotation. However, instead of this, the rotational speed of the spindle motor 22 is randomly changed by using a drive signal that is output from an optical axis drive circuit configured in the same manner as the optical axis drive circuits 81 to 84 and changes randomly. You may make it change the space | interval of the rotation direction of the pit formed in the surface of the target object OB at random. In this case, the basic rotation speed Ro is output to the spindle motor control circuit 61 by the processing of steps S402 to S404 in the spindle motor control data generation program of FIG. Then, the drive signal is supplied to the spindle motor control circuit 61. The spindle motor control circuit 61 controls the rotation of the spindle motor 22 by controlling the rotation of the spindle motor 22 with a signal obtained by adding the drive signal to the basic rotation speed Ro. The speed may be changed by the drive signal with respect to the basic rotation speed Ro.

  Moreover, in the said embodiment and modification, it forms on the surface of the workpiece OB by outputting correction | amendment radial direction moving speed Fr 'to the feed motor control circuit 62, and changing the rotational speed of the feed motor 23 at random. The pit radial interval was changed randomly. However, instead of this, as in the case described above, the rotational speed of the feed motor 23 is adjusted using a drive signal that is output from an optical axis drive circuit configured similarly to the optical axis drive circuits 81 to 84 and changes at random. You may make it change at random and change the space | interval of the radial direction of the pit formed in the surface of the workpiece OB at random. In this case, the basic radial direction moving speed Fr is output to the feed motor control circuit 62 by the processing of steps S502 to S503 in the feed motor control data generation program of FIG. Then, the drive signal is supplied to the feed motor control circuit 62. The feed motor control circuit 62 adds the rotation control of the feed motor 23 by the drive signal to the control of the rotation speed of the feed motor 23 by the basic radial direction moving speed Fr. Thus, the rotational speed of the feed motor 23 may be varied by the amount corresponding to the drive signal with respect to the rotational speed corresponding to the basic radial direction moving speed Fr.

  Further, in the above embodiment and the modification, the pulse signal supply circuit 72 is stored in the memory 72a by executing the pulse control data generation routine by the controller 50, and the correction pulse width Wd (n ) And the correction level value Pw (n) of the high-side pulse, the pulse width of the low-side pulse and the level value of the high-side pulse of each pulse train signal are randomly changed. However, instead of this, the index signal Index is supplied from the encoder 22a to the pulse signal supply circuit 72 as shown by the broken lines in FIGS. The pulse signal supply circuit 72 receives the correction pulse width Wd (n) of the low-side pulse and the correction level value of the high-side pulse every time the index signal Index is input, that is, every time the workpiece OB rotates once. Pw (n) may be used to randomly change the pulse width of the low-side pulse and the level value of the high-side pulse of the pulse train signal. According to this, since the pulse width of the low-side pulse and the level value of the high-side pulse of the pulse train signal are changed only for each rotation of the workpiece OB, the degree of randomness is low, but the workpiece OB When viewed throughout the formed pits, the interval between the pits in the rotational direction and the size of the pits change randomly. In this case, the capacity of the memory 72a in the pulse signal supply circuit 72 can be kept small.

  In the above-described embodiment and modification, acousto-optic modulation elements (EOD) 43 and 47 are used to randomly change the pits formed on the surface of the workpiece OB in the radial direction and the rotation direction. However, instead of the acousto-optic modulation elements 43 and 47, electro-optic modulation elements may be used. In this case, the electro-optic modulation element may be driven and controlled by a drive signal from an optical axis drive circuit configured similarly to the optical axis drive circuits 81 and 84. Also by this, since the electro-optic modulation element has a good time response, it is extremely effective for random control when the table 21 is rotated at a high speed to form pits with fine intervals on the workpiece OB.

  In the above-described embodiment, random control of the tracking actuator 44, the mirror 45, and the mirror actuator 46 is employed in order to randomly change the pits formed on the surface of the workpiece OB in the radial direction. However, instead of this, using a polygon mirror and an actuator for driving the polygon mirror, an actuator for driving the galvano mirror and the galvano mirror, an actuator for driving the laser light source 31, etc., the optical axis of the laser light is randomly selected in the radial direction. The pits formed on the surface of the workpiece OB may be changed randomly in the radial direction. Also in this case, the actuator may be driven and controlled by a drive signal from an optical axis drive circuit similar to the optical axis drive circuits 82 and 83 of the above embodiment. Further, in order to randomly change the pits formed on the surface of the workpiece OB in the rotational direction, the mirror 45 and the mirror actuator 46 of the above embodiment, the polygon mirror and the actuator for driving the polygon mirror of the modification, a galvano An actuator that drives the mirror and the galvanometer mirror, an actuator that drives the laser light source 31, and the like may be used. Also in this case, the actuator may be driven and controlled by a drive signal from an optical axis drive circuit similar to the optical axis drive circuits 82 and 83 of the above embodiment. However, in this case, it is necessary to change the optical axis of the laser light in the rotation direction by driving the mirror 45, the polygon mirror, the galvanometer mirror, the galvanometer mirror, and the laser light source 31.

Further, in the above embodiment, the controller 50 executes the spindle motor control data generation program of FIG. 8 and the feed motor control data generation program of FIG. 9 in parallel with the machining control program of FIG. However, instead of this, the controller 50 interrupts the spindle motor control data generation program of FIG. 8 and the feed motor control data generation program of FIG. 9 at predetermined intervals during execution of the machining control program of FIG. You may make it do. In this case, in the spindle motor control data generation program of FIG. 8, the initial setting process of the variable n in step S401 is omitted, and the initial setting program prepared separately at the first execution of the spindle motor control data generation program is executed. The variable n is initialized to “1”. If no index signal Index is input in step S402, it is determined as “No” in step S402, and the execution of the spindle motor control data generation program is terminated. However, in this case, the index signal Index input from the encoder 22a needs to be stored in the controller 50 for a short time. In addition, after the processing in step S409, the execution of the spindle motor control data generation program is terminated. Furthermore, when “Yes”, that is, the variable n reaches the maximum value n _max in step S408, the variable n is initialized to “1”, and then the execution of the spindle motor control data generation program is terminated. .

In the feed motor control data generation program of FIG. 9, the initial setting process of the variable m in step S501 is omitted, and the initial setting program prepared at the first execution of the feed motor control data generation program is executed. The variable m is initialized to “1”. In addition, after the process of step S508, the execution of the feed motor control data generation program is terminated. Further, if “Yes”, that is, the variable m reaches the maximum value m _max in step S507, the variable m is initialized to “1”, and then the execution of the feed motor control data generation program is terminated. .

  In the above embodiment, the table 21 is moved when the irradiation position of the laser beam is moved in the radial direction of the table 21. However, the processing head 30 is moved in the radial direction of the table 21. May be. Further, both the table 21 and the processing head 30 can be moved in association with each other.

  Furthermore, in the above-described embodiment, fine pits are formed on the LED production substrate. However, in the case of forming fine reaction traces in which pits are formed by post-processing of a developer or the like, the above-described embodiment is also used. The laser processing apparatus and laser processing method which concern on can be utilized. Further, the laser processing apparatus and the laser processing method according to the above-described embodiment can be used even when fine pits or fine reaction traces are randomly formed on a flat plate other than the LED production substrate.

DESCRIPTION OF SYMBOLS 21 ... Table, 22 ... Spindle motor, 23 ... Feed motor, 30 ... Processing head, 31 ... Laser light source, 35 ... Objective lens, 43, 47 ... Acoustooptic modulator, 44 ... Tracking actuator, 45 ... Mirror, 46 ... Mirror Actuator, 50 ... Controller, 52 ... Radius value detection circuit, 61 ... Spindle motor control circuit, 62 ... Feed motor control circuit, 63 ... Radius value detection circuit, 72 ... Pulse signal supply circuit, 81-84 ... Optical axis drive circuit

Claims (12)

A table for setting the workpiece,
Rotating means for rotating the table;
A processing head for condensing and irradiating a laser beam emitted from a laser light source on a workpiece to be set and rotated by the objective lens;
Radial direction moving means for moving a laser spot formed on the object to be processed by the laser light emitted from the processing head in the radial direction of the table relative to the table;
A laser light source driving unit configured to generate a pulse train drive signal and supply the laser light source to drive the laser light source so that a pulse train laser beam is emitted from the laser light source;
In the laser processing apparatus adapted to form a plurality of processing marks along the rotation direction of the table as well as along the radial direction of the table on the processing object,
As interval of the plurality of processing traces formed along the radial direction of the table is changed at random, a random controlling means for controlling the formation of said plurality of processing marks are irradiated to the processing object A laser processing apparatus comprising a radial random control means for randomly changing the optical axis of the laser beam in the radial direction of the table . The laser processing apparatus according to claim 1 ,
The radial random control means,
An acousto-optic modulation element or electro-optical element arranged on the optical path of laser light from the laser light source to the objective lens, and for changing the optical axis of the laser light irradiated on the workpiece in the radial direction of the table A modulation element;
An electrical signal that randomly changes is supplied to the acousto-optic modulation element or the electro-optic modulation element, and the optical axis of the laser beam irradiated onto the workpiece by the acousto-optic modulation element or the electro-optic modulation element is A laser processing apparatus configured with an optical axis driving circuit for controlling the acousto-optic modulation element or the electro-optic modulation element so as to be randomly changed in a radial direction. The laser processing apparatus according to claim 1 ,
The radial random control means,
An actuator for driving the objective lens to change the optical axis of the laser light applied to the object to be processed in the radial direction of the table;
The actuator is controlled such that an electric signal that randomly changes is supplied to the actuator, and the objective lens randomly changes the optical axis of the laser light applied to the object to be processed in the radial direction of the table. A laser processing device composed of an optical axis drive circuit. The laser processing apparatus according to claim 1 ,
The radial random control means,
A mirror disposed on the optical path of laser light from the laser light source to the objective lens, and reflecting the laser light from the laser light source and guiding it to the objective lens;
An actuator for driving the mirror to change the optical axis of the laser beam irradiated to the workpiece in the radial direction of the table;
Light that controls the actuator by supplying an electrical signal that randomly changes to the actuator, so that the mirror randomly changes the optical axis of the laser beam irradiated on the workpiece in the radial direction of the table. A laser processing device composed of a shaft drive circuit. In the laser processing apparatus as described in any one of Claims 1 thru | or 4 ,
Random control means for controlling the formation of the plurality of machining traces such that the intervals between the plurality of machining traces formed along the radial direction of the table are randomly changed, wherein the radial movement means is electrically is controlled to, characterized in that a radial movement speed random control means for changing at random the movement speed of the laser spot moves radially relatively the table for the table by the radial moving means laser processing apparatus according to. In the laser processing apparatus as described in any one of Claims 1 thru | or 5 ,
Random control means for controlling the formation of the plurality of machining traces so that the intervals between the plurality of machining traces formed along the rotation direction of the table change randomly, and irradiates the workpiece. A laser processing apparatus comprising a rotation direction random control means for randomly changing an optical axis of a laser beam in a rotation direction of the table. The laser processing apparatus according to claim 6 ,
The rotation direction random control means,
An acousto-optic modulation element or electro-optical element arranged on the optical path of laser light from the laser light source to the objective lens, and for changing the optical axis of the laser light irradiated on the workpiece in the rotation direction of the table A modulation element;
An electrical signal that randomly changes is supplied to the acousto-optic modulation element or the electro-optic modulation element, and the optical axis of the laser beam irradiated onto the workpiece by the acousto-optic modulation element or the electro-optic modulation element is A laser processing apparatus configured with an optical axis driving circuit for controlling the acousto-optic modulation element or the electro-optic modulation element so as to change randomly in the rotation direction. The laser processing apparatus according to claim 6 ,
The rotation direction random control means,
An actuator for driving the objective lens to change the optical axis of the laser light applied to the object to be processed in the rotation direction of the table;
The actuator is controlled so that an electric signal that randomly changes is supplied to the actuator, and the objective lens randomly changes the optical axis of the laser light applied to the object to be processed in the rotation direction of the table. A laser processing device composed of an optical axis drive circuit. The laser processing apparatus according to claim 6 ,
The rotation direction random control means,
A mirror disposed on the optical path of laser light from the laser light source to the objective lens, and reflecting the laser light from the laser light source and guiding it to the objective lens;
An actuator for driving the mirror to change the optical axis of the laser beam irradiated to the workpiece in the rotation direction of the table;
Light that controls the actuator so as to supply an electrical signal that randomly changes to the actuator so that the mirror randomly changes the optical axis of the laser light applied to the workpiece in the rotation direction of the table. A laser processing device composed of a shaft drive circuit. In the laser processing apparatus as described in any one of Claims 1 thru | or 9 ,
Random control means for controlling the formation of the plurality of machining traces such that the intervals between the plurality of machining traces formed along the rotation direction of the table change randomly, and electrically controls the rotation means. Then , a laser processing apparatus comprising a rotation speed random control means for randomly changing the rotation speed of the table rotated by the rotation means. In the laser processing apparatus as described in any one of Claims 1 thru | or 10 ,
Random control means for controlling the formation of the plurality of machining traces so that the intervals between the plurality of machining traces formed along the rotation direction of the table change randomly, and generated by the laser light source driving means A laser processing apparatus characterized by comprising pulse interval random control means for randomly changing a pulse interval in a drive signal in the form of a pulse train. In the laser processing apparatus according to any one of claims 1 to 11 ,
Random control means for controlling the formation of the plurality of processing traces so that the sizes of the plurality of processing traces to be randomly changed, the pulse train drive generated by the laser light source driving means A laser processing apparatus comprising pulse level random control means for randomly changing a pulse level in a signal.

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