JP2011104630A - Laser beam machining apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control a laser beam to be focused on the proper position of a workpiece, with a simple structure, even in machining the surface of a cylindrical workpiece having a small diameter with a laser beam. <P>SOLUTION: A cylindrical workpiece OB extending in the X axis direction is irradiated with a machining laser beam in the Z axis direction from a machining head 10 and also irradiated with a servo laser beam in the Z axis direction from the servo Z axis direction optical head 20. Thus, deviation in the Y axis direction of the workpiece OB is detected by the position of the projection of the workpiece OB projected on a photodetector 118. A Y axis direction servo circuit 162 or the like drives an objective lens 112 in the Y axis direction by servo control in accordance with the deviation in the Y axis direction. A delay circuit 164 delays the signal of the Y axis direction servo control, thereby driving the objective lens 112 in the Z axis direction. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a laser processing apparatus that performs laser processing on the surface of a cylindrical workpiece having a small diameter.

  Conventionally, a sheet-like workpiece is fixed to the outer peripheral surface of a drum-shaped fixing jig, and the fixing jig is moved along the axial direction while rotating around its central axis. Laser processing apparatuses that perform laser processing (formation of pits, grooves, reaction traces, etc.) spirally on the surface of the processing object by condensing light with an objective lens and irradiating the surface of the processing object are known. Yes. Such a laser processing apparatus is proposed in Patent Document 1 below, for example.

  When performing fine laser processing on an object to be processed in the drum type laser processing apparatus, for example, as proposed in Patent Document 2 below, the reflected light from the object to be processed is the same as the focus servo control in the optical disk apparatus. Is received by a photodetector having a light-receiving area divided into four parts, and a focus corresponding to a deviation in the optical axis direction between the focal position of the laser beam and the surface of the workpiece from the light-receiving signal of each light-receiving area by an astigmatism method or the like Generate an error signal. Then, by moving the objective lens that collects the laser light in the optical axis direction of the laser light so that the value of the focus error signal becomes zero, the focal position of the laser light coincides with the surface of the workpiece. I am doing so.

JP-A-8-132268 JP 2001-243663 A

  However, the focus servo control is based on the premise that the surface of the workpiece can be irradiated perpendicularly with the laser beam, but the workpiece is a very thin cylindrical member (for example, a cylindrical pipe having a diameter of 50 μm). In some cases, if the optical axis of the laser beam is deviated from the central axis of the cylindrical member (does not intersect), the laser beam is irradiated obliquely onto the surface of the workpiece, so an appropriate focus error The signal cannot be generated. In such a case, in addition to the change in the optical axis direction of the laser beam of the workpiece, the change in the direction perpendicular to the optical axis must be considered. Therefore, in the conventional focus servo control, it is impossible to control the laser beam so that the focus of the laser beam is an appropriate position of the workpiece.

  The present invention has been made to address the above-described problem. Even when the surface of a cylindrical workpiece having a small diameter is laser-processed, the laser beam is focused on the workpiece with a simple configuration. It aims at controlling so that it may become an appropriate position. 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 provides an object support means (51) for supporting a cylindrical object (OB) having a small diameter with its central axis direction as the X-axis direction, and a processing laser. A Z-axis direction perpendicular to the X-axis direction on the surface of the workpiece is processed laser light emitted from the processing laser light source and condensed by the objective lens, having a light source (102) and an objective lens (112). Laser beam irradiating means for irradiating, and a Y-axis actuator for moving the optical axis of the laser beam for processing in the Y-axis direction by displacing the objective lens in the Y-axis direction orthogonal to the X-axis direction and the Z-axis direction (114y), a Z-axis actuator (114z) that moves the focal position of the processing laser light in the Z-axis direction by displacing the objective lens in the Z-axis direction, and a processing object or processing laser light irradiation means X Rotate around axial direction The rotating means (52) for rotating the irradiation position of the processing laser light on the processing object relative to the processing object around the X-axis direction, and the processing object or the processing laser light irradiation means. Laser processing apparatus provided with moving means (53-55) that is displaced in the X-axis direction and moves the irradiation position of the processing laser light on the processing object relative to the processing object in the X-axis direction , The servo laser light irradiation means (20, 130) for irradiating the processing object with the servo laser light whose irradiation direction is set in the Z-axis direction, and the processing object generated based on the servo laser light A deviation in which a laser beam including information representing a position in the Y-axis direction is received, and a received light signal representing a deviation amount in the Y-axis direction of the center axis in the X-axis direction of the workpiece to be processed with respect to the optical axis of the machining laser beam Photodetector for detection 118, 140) and the received light signal output from the photodetection detector for deviation detection, a control signal for causing the optical axis of the laser beam for processing to intersect the central axis in the X-axis direction of the workpiece is generated, Y-axis servo control means (161 to 163) for driving and controlling the Y-axis actuator in accordance with the control signal to cross the optical axis of the machining laser beam with the central axis in the X-axis direction of the workpiece, and deviation detection The light reception signal output from the photo detector or the control signal generated by the Y-axis direction servo control means is input, and the deviation in the Y-axis direction is relative to the irradiation position of the processing laser beam by the rotating means around the X-axis direction. The input light reception signal or control signal is delayed by the time required to appear as a shift in the Z-axis direction with rotation, and the Z-axis actuator is used using the delayed light reception signal or control signal. There is provided Z-axis direction servo control means (164, 165) for driving and controlling the eta so that the focal position of the machining laser beam coincides with the outer peripheral surface of the workpiece.

  In this case, in order for the deviation detection photo detector to receive the laser beam generated based on the servo laser beam and including the information indicating the position of the workpiece in the Y-axis direction, the servo laser beam irradiation means A parallel laser beam having a diameter larger than the diameter of the object is used as a servo laser beam so that the object to be processed is irradiated at a position where the optical axis is the same as that of the processing laser beam. The laser light including the projection of the object to be processed may be received as the laser light including information indicating the position of the object in the Y-axis direction. Further, the laser beam irradiation means for servo irradiates the object to be processed at a position where the optical axis of the laser beam for processing is the same as the laser beam for processing as the laser beam condensed to the same degree as the laser beam for processing, Reflected light of servo laser light from the processing object as a laser light including information indicating the position of the processing object in the Y-axis direction at a position where the optical axis is the same as the processing laser light. May be received.

  In the present invention configured as described above, the laser beam for servo whose irradiation direction is set in the Z-axis direction is irradiated to the object to be processed, and the photo detector for detecting the deviation is generated based on the laser beam for servo and processed. A laser beam including information indicating the position of the object in the Y-axis direction is received, and a light-receiving signal indicating a deviation amount in the Y-axis direction of the central axis of the processing object in the X-axis direction with respect to the optical axis of the processing laser beam is received Output. Then, the Y-axis direction servo control means uses the received light signal output from the deviation detection photodetector to generate a control signal for causing the optical axis of the processing laser light to intersect the central axis in the X-axis direction of the processing target. The Y-axis actuator is generated and driven and controlled so that the optical axis of the processing laser beam intersects the central axis in the X-axis direction of the workpiece. The time required for the Z-axis direction servo control means to appear as a shift in the Z-axis direction due to the relative rotation around the X-axis direction of the irradiation position of the processing laser beam by the rotating means. Only by delaying the light reception signal or control signal input from the photodetector for detecting deviation or the Y-axis direction servo control means, and using the delayed light reception signal or control signal to drive and control the Z-axis actuator, The focal position is matched with the outer peripheral surface of the workpiece.

  Therefore, according to the present invention, even when the outer peripheral surface of a cylindrical workpiece having a small diameter is subjected to laser processing, it is possible to irradiate the outer peripheral surface of the workpiece with the focused laser beam that is properly condensed perpendicularly. it can. As a result, the outer peripheral surface of the object to be processed can be precisely laser processed, and a spiral processing mark having an appropriate width can be formed on the outer peripheral surface of the object to be processed. Further, according to the present invention, the Z-axis direction servo control means delays the light reception signal or control signal input from the deviation detection photodetector or the Y-axis direction servo control means, and uses the delayed light reception signal or control signal. Since the Z-axis actuator is driven and controlled, servo laser irradiation means for irradiating the laser beam in the Y-axis direction for detecting the deviation of the focal position of the processing laser light from the outer peripheral surface of the processing object, and A shift detection photodetector that receives the laser beam irradiated in the Y-axis direction is not required, and the entire laser processing apparatus can be easily configured.

  Another feature of the present invention is that the servo laser light irradiation means (20) is irradiated from the processing laser light irradiation means with a parallel laser light having a diameter larger than the diameter of the workpiece as servo laser light. The processing object is irradiated at a position where the optical axis is the same as that of the processing laser light and from the direction opposite to the irradiation direction of the processing laser light, and the deviation detection photo-detector (118) The laser beam including the projection is received, and the processing laser beam irradiation means separates the servo laser beam incident on the optical path from the optical path in the middle of the optical path for irradiating the workpiece with the processing laser beam. A separation optical element (110) led to the detection photodetector is provided.

  In another aspect of the present invention, the processing laser beam and the servo laser beam are irradiated on the same optical axis, and the shift detection photodetector is used for a servo having the same optical axis as the processing laser beam. Based on the laser light, a light reception signal representing the amount of deviation in the Y-axis direction of the central axis of the workpiece in the X-axis direction with respect to the optical axis of the processing laser light is output. Then, the Y-axis direction servo control means drives and controls the Y-axis direction actuator so that the optical axis of the processing laser beam intersects the central axis in the X-axis direction of the workpiece using this received light signal. The axis actuator is driven and controlled by closed loop control, and particularly Y-axis direction servo control can be performed with high accuracy.

  Another feature of the present invention is that the servo laser beam irradiation means (130) uses the laser beam focused by the objective lens as much as the processing laser beam as the servo laser beam, and the processing laser beam and light. The workpiece is irradiated at a position where the axes are the same, and the deviation detection photodetector (144) receives reflected light of the servo laser beam from the workpiece, and the processing laser beam irradiation means is a processing laser. In the middle of the optical path for irradiating the workpiece with light, a separation optical element (110) for separating the reflected light of the servo laser beam from the workpiece and separating it from the optical path and guiding it to a photodetection detector for displacement detection was provided. It is in.

  In another aspect of the present invention, the laser beam condensed by the objective lens to the same extent as the processing laser beam is used as a servo laser beam at a position where the processing laser beam and the optical axis are the same. The deviation detection photo-detector is based on the reflected light of the servo laser light from the workpiece, and the amount of deviation in the Y-axis direction of the central axis of the workpiece in the X-axis direction with respect to the optical axis of the machining laser light A light receiving signal representing is output. Then, the Y-axis direction servo control means drives and controls the Y-axis direction actuator so that the optical axis of the processing laser beam intersects the central axis in the X-axis direction of the workpiece using this received light signal. Accordingly, in this case as well, the Y-axis actuator is driven and controlled by closed-loop control, and particularly Y-axis servo control can be performed with high accuracy. Further, in this case, the detection position of the reflected light of the servo laser light greatly varies with respect to the displacement of the workpiece in the Y-axis direction, so that the Y-axis direction servo control can be performed with high accuracy.

  Furthermore, another feature of the present invention is that the reflected light of the processing laser light irradiated on the surface of the processing object is received by the processing laser light irradiation means, and a received light signal indicating the intensity of the reflected light is output. When the intensity detection photodetector (122) and the light reception signal output from the intensity detection photodetector are input, and the intensity of the reflected light represented by the input light reception signal is equal to or less than a reference value, the processing laser beam Determination means (90, step S116) for determining that the focal position is not appropriate.

  In the present invention described above, the intensity detection photodetector outputs a light reception signal indicating the intensity of the reflected light of the processing laser light irradiated on the surface of the object to be processed, and the determination means reflects the reflected light represented by the light reception signal. When the intensity of the laser beam is below the reference value, it is determined that the focal position of the processing laser beam is not appropriate. Therefore, before starting laser processing, check whether the focus servo control is properly performed by the judging means with the Y-axis direction servo control means and the Z-axis direction servo control means activated. Can do. For this reason, it becomes possible to prevent the failure of laser processing.

  Furthermore, the implementation of the present invention is not limited to the invention of the laser processing apparatus, and can also be implemented as a method invention.

1 is a system configuration diagram of a laser processing apparatus according to a first embodiment of the present invention. It is a schematic block diagram of the processing head and servo Z-axis direction optical head of the laser processing apparatus according to the first embodiment. It is explanatory drawing showing an X-axis direction, a Y-axis direction, and a Z-axis direction. It is explanatory drawing showing the state of the projection irradiated to the photodetector of FIG.1 and FIG.2. It is a characteristic view showing the relationship between the displacement of a workpiece and an error signal waveform value. It is a flowchart showing a laser processing control routine. It is the figure which looked at the mode when a processing target object rotates in the direction of a rotation axis. (A) is a waveform diagram showing a change in deviation in the Y-axis direction with respect to the rotation angle of the workpiece, and (B) is a waveform diagram showing a change in deviation in the Z-axis direction with respect to the rotation angle of the workpiece. It is a schematic block diagram of the process head of the laser processing apparatus which concerns on 2nd Embodiment. It is a figure showing the relationship between the displacement of the workpiece in FIG. 9, and the position change of the reflected light irradiated to the photodetector.

a. First Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a system configuration diagram of the laser processing apparatus according to the first embodiment of the present invention. This laser processing apparatus performs laser processing by irradiating the surface of a cylindrical processing object OB having a small diameter spirally with a processing laser beam. The laser processing apparatus holds the workpiece OB and rotates it around the central axis of the workpiece OB, and moves the workpiece OB in the direction of the central axis, and the surface of the workpiece OB. A processing head 10 for irradiating a processing laser beam (see FIG. 2), a servo Z-axis direction optical head 20 for irradiating the surface of the workpiece OB with a servo Z-axis direction laser beam (see FIG. 2); Various electric circuits (described later) and a controller 90 for controlling the operation of the entire laser processing apparatus are provided.

  Here, the direction in the laser processing apparatus is defined. As shown in FIG. 3, the central axis direction of the workpiece OB fixed to the workpiece driving device 50 is referred to as an X-axis direction. The direction of the optical axis of the processing laser beam that is orthogonal to the X-axis direction and is irradiated from the processing head 10 onto the processing object OB is referred to as the Z-axis direction. A direction orthogonal to both the X-axis direction and the Z-axis direction is referred to as a Y-axis direction.

  The processing object OB in the present embodiment is a nickel pipe having a diameter of 50 μm whose surface is coated with a photoresist. This object to be processed OB is finally processed into a pipe used for manufacturing a microspring having a diameter of 50 μm. The laser processing apparatus according to the present embodiment spirals a processing laser beam on the surface of a photoresist. Is used as an apparatus for forming a spiral reaction trace in a photoresist. Thereafter, the processing object OB is immersed in a developing solution to remove the reaction trace, and is etched using the remaining photoresist as a mask. As a result, a spiral opening is formed in the nickel pipe, and a microspring-producing pipe is produced.

  When laser processing is performed on a pipe-shaped workpiece OB having a very thin diameter as described above, a focus error is generated from the reflected light of the processing laser beam by an astigmatism method or the like as conventionally known. Even if the signal is generated, if the optical axis of the machining laser beam deviates from the center axis of the workpiece OB, an appropriate focus error signal cannot be obtained, and the machining laser beam is focused on the workpiece OB. It cannot be adjusted to the outer peripheral surface. Therefore, in the present embodiment, the processing object OB is irradiated with servo laser light in the Z-axis direction, and the focal position of the processing laser light is adjusted in the Y-axis direction based on the position of the projection on which the processing object OB is projected. The optical axis of the laser beam for processing intersects the central axis of the workpiece OB, and the signal for controlling in the Y-axis direction is delayed to control the focal position of the processing laser beam in the X-axis direction. Thus, the focal position of the processing laser beam is made to coincide with the outer peripheral surface of the processing object OB.

  First, the work driving device 50 will be described. The work drive device 50 includes a moving stage 51 that chucks and holds both ends of the processing object OB, and a spindle motor 52 that rotates the processing object OB held on the moving stage 51 around its central axis. And a screw feed mechanism 53 for moving the moving stage 51 in the X-axis direction.

  The screw feed mechanism 53 includes a screw rod 54 that is screwed into a nut (not shown) fixed to the moving stage 51, and a feed motor 55 that rotates the screw rod 54. The screw rod 54 is provided so as to extend in the X-axis direction parallel to the central axis of the workpiece OB held by the moving stage 51 (that is, the rotation axis of the spindle motor 52), and one end side of the screw rod 54 is the laser processing apparatus main body. It is connected to an output shaft of a feed motor 55 fixed to a frame (not shown), and the other end is rotatably supported by a bearing portion (not shown) fixed to the laser processing apparatus main body frame. The moving stage 51 is restricted in rotation by a guide guide (not shown) and can move only in the X-axis direction. Therefore, when the feed motor 55 is driven forward or reversely, the rotational motion of the feed motor 55 is converted into the linear motion of the moving stage 51 so that the workpiece OB can move forward or backward in the X-axis direction.

  An encoder 52 a is incorporated in the spindle motor 52. The encoder 52a outputs a pulse train signal whose output is alternately switched between a high level and a low level every time the spindle motor 52 rotates by a predetermined minute rotation angle. The pulse train signal output from the encoder 52 a is input to the spindle motor control circuit 56. The spindle motor control circuit 56 starts operating in response to an instruction from the controller 90, calculates the rotational speed of the spindle motor 52 from the number of pulses per unit time of the pulse train signal output from the encoder 52a, and the calculated rotational speed is the controller 90. The rotation of the spindle motor 52 is controlled to be equal to the rotation speed set by.

  An encoder 55 a is also incorporated in the feed motor 55. The encoder 55a outputs a pulse train signal whose output is alternately switched between a high level and a low level each time the feed motor 55 rotates by a predetermined minute rotation angle. The pulse train signal output from the encoder 55 a is input to the feed motor control circuit 57 and the movement position detection circuit 58. The movement position detection circuit 58 starts operating in response to an instruction from the controller 90. After the operation starts, when the pulse signal output from the encoder 55a is not input, the movement position detection circuit 58 outputs a signal indicating the movement limit position to the feed motor control circuit 57. Then, the count value is set to “0”, and thereafter, the number of pulses of the pulse signal output from the encoder 55a is counted. Then, the moving position of the moving stage 51 is calculated from the accumulated count number and output to the controller 90 and the feed motor control circuit 57. The movement limit position where the count value is “0” is the origin position for controlling the movement position of the movement stage 51.

  The feed motor control circuit 57 starts to operate in response to an instruction from the controller 90. When the moving position setting value is input from the controller 90, the moving position output from the moving position detection circuit 58 is input at a predetermined time interval. The feed motor 55 is driven to move the moving stage 51 until the moving position reaches the set value input from the controller 90. When the set value of the movement position is input immediately after the start of operation, the feed motor 55 is driven to move the movement stage 51 in the movement limit position direction, and a signal indicating the movement limit position is input from the movement position detection circuit 58. Then, the drive signal output to the feed motor 55 is stopped. Thereafter, the feed motor 55 is driven to move the moving stage 51 until the movement position output from the movement position detection circuit 58 reaches the set value of the movement position input from the controller 90.

  In addition, a set value (set speed) of the moving speed of the moving stage 51 is input to the feed motor control circuit 57 by the controller 90. When a movement start instruction is input from the controller 90, the moving speed of the moving stage 51 is calculated from the number of pulses per unit time of the pulse train signal output from the encoder 55a, so that the calculated moving speed becomes the set speed. The feed motor 55 is driven and controlled.

  Next, the processing head 10 will be described with reference to FIG. The processing head 10 receives the processing laser beam irradiated from the servo Z-axis direction optical head 20 with the function of irradiating the cylindrical surface of the processing object OB with the processing laser beam, and the processing target object. And a function of outputting a signal corresponding to the deviation of the OB in the Y-axis direction. The processing head 10 includes a laser light source 102 that emits processing laser light, a collimator lens 104 that is provided along the optical axis of the processing laser light emitted from the laser light source 102, a polarization beam splitter 106, and a quarter wavelength. A plate 108, a dichroic mirror 110, and an objective lens 112 are provided.

  The laser light source 102 is driven by the current and voltage supplied from the processing laser drive circuit 150 and emits processing laser light. The processing laser light emitted from the laser light source 102 is collimated by the collimator lens 104 and enters the polarization beam splitter 106. Most of the processing laser light (for example, 95%) passes through the polarization beam splitter 106 as it is, passes through the quarter wavelength plate 108, and is converted from linearly polarized light to circularly polarized light. The processing laser light that has passed through the quarter-wave plate 108 passes through the dichroic mirror 110 and enters the objective lens 112. Thus, the processing laser light is condensed on the surface of the processing object OB by the objective lens 112.

  The objective lens 112 is provided with a focus actuator 114. The focus actuator 114 includes a Z-axis actuator 114z that moves the objective lens 112 in the optical axis direction of the processing laser beam, that is, the Z-axis direction, and a Y-axis actuator 114y that moves the objective lens 112 in the Y-axis direction. . Therefore, by operating the Z-axis actuator 114z, the focal position of the processing laser beam can be moved in the Z-axis direction (optical axis direction), and by operating the Y-axis actuator 114y, the focal position of the processing laser beam (that is, light) The axis) can be moved in the Y-axis direction. The objective lens 112 is located at the center of the movable range in the Z-axis direction and the Y-axis direction when the actuators 114z and 114y are not energized. Hereinafter, this position is referred to as the origin position of the objective lens 112. An actuator that drives the objective lens in the biaxial direction is known from, for example, Japanese Patent Application Laid-Open No. 2004-39065.

  The processing laser light condensed by the objective lens 112 is irradiated onto the surface of the processing object OB and reflected. The reflected light reflected by the object OB passes through the objective lens 112, the dichroic mirror 110, and the quarter wavelength plate 108. In this case, since the reflected light has passed through the quarter-wave plate 108 twice, the direction of polarization differs from that of the laser light emitted from the laser light source. Therefore, the reflected light that has passed through the quarter-wave plate 108 is reflected by the polarization beam splitter 106. A condenser lens 120 and a photodetector 122 are provided in the reflection direction of the polarizing beam splitter 106. For this reason, the reflected light reflected by the polarization beam splitter 106 is condensed on the photodetector 122 by the condenser lens 120.

  The photodetector 122 is a light receiving element that outputs a light reception signal corresponding to the intensity of light collected on the light receiving surface. Therefore, the photodetector 122 outputs a light reception signal corresponding to the intensity of the reflected light reflected from the processing object OB by the processing laser light. The light reception signal output from the photodetector 122 is amplified by the amplifier circuit 152 and supplied to the A / D converter 153. The A / D converter 153 operates according to a command from the controller 90, converts the intensity (instantaneous value) of the received light signal supplied from the amplifier circuit 152 into a digital signal, and outputs the digital signal to the controller 90. The controller 90 determines whether servo control in the Z-axis direction and Y-axis direction, which will be described later, is appropriately performed from the reflected light intensity represented by the light reception signal.

  Further, the processing head 10 reflects a part (for example, 5%) of the processing laser light emitted from the laser light source 102 by the polarization beam splitter 106, and the reflected light is received by the photodetector 126 by the condenser lens 124. A configuration for condensing light onto the surface is provided. Similar to the photodetector 122, the photodetector 126 is a light receiving element that outputs a light reception signal corresponding to the intensity of light collected on the light receiving surface. Therefore, the photodetector 126 outputs a light reception signal corresponding to the intensity of the processing laser beam emitted from the laser light source 102. This received light signal is supplied to the processing laser drive circuit 150.

  Based on a command from the controller 90, the processing laser drive circuit 150 has a processing intensity for the laser light source, that is, an intensity capable of appropriately processing the surface of the processing object OB (in this example, a reaction trace is recorded on the photoresist). This is a circuit for supplying a current and a voltage for emitting a laser beam having an intensity that can be formed. In the present embodiment, the processing laser drive circuit 150 feeds back the light reception signal output from the photodetector 126 and supplies the current or voltage output to the laser light source 102 so that the intensity of the light reception signal becomes a preset set intensity. adjust. Thereby, the intensity of the processing laser beam applied to the processing object OB is maintained at the setting processing intensity.

  In the processing laser drive circuit 150, the output form of the drive signal to the laser light source 102 is controlled by the light emission signal supply circuit 151. The light emission signal supply circuit 151 receives data representing a machining pattern from the controller 90 and supplies a pulse train signal or a continuous signal corresponding to the data to the machining laser drive circuit 150 during laser machining. In this embodiment, since a continuous spiral reaction trace is formed on the photoresist on the surface of the workpiece OB, a continuous signal is output from the light emission signal supply circuit 151. When the pits are formed in a row, a pulse train signal including a high level signal and a low level signal having a time width corresponding to the pit length and the pit formation interval is output.

  The processing head 10 is further provided with a relay lens (imaging lens) 116 and a photodetector 118 in the reflection direction of the dichroic mirror 110. The relay lens 116 and the photodetector 118 are provided for detecting servo Z-axis direction laser light emitted from the servo Z-axis direction optical head 20. Accordingly, the servo Z-axis direction optical head 20 will be described first.

  As shown in FIG. 2, the servo Z-axis direction optical head 20 is paired with the processing head 10 so as to face the processing head 10 with the processing object OB interposed therebetween. Abbreviated). The servo Z-axis direction optical head 20 includes a laser light source 202 that emits servo laser light, a collimator lens 204 and a polarization beam splitter 206 that are provided along the optical axis of the servo laser light emitted from the laser light source 202. And a condenser lens 208 and a photodetector 210 provided in the reflection direction of the polarization beam splitter 206.

  The laser light source 202 is driven by the current and voltage supplied from the servo Z-axis direction laser drive circuit 240 to emit servo laser light. The servo laser light emitted from the laser light source 202 is collimated by the collimator lens 204 and enters the polarization beam splitter 206. Most of the servo laser light (for example, 95%) passes through the polarization beam splitter 206 as it is and exits from the servo Z-axis direction optical head 20. The laser beam emitted from the servo Z-axis direction optical head 20 is the servo Z-axis direction laser beam. The servo Z-axis direction laser light becomes parallel light having a diameter larger than the diameter of the workpiece OB.

  The servo Z-axis direction optical head 20 is a processing head when the servo Z-axis direction laser light is emitted in the Z-axis direction and the optical axis of the objective lens 112 of the processing head 10 is at the origin position. The laser beam is positioned so as to coincide with the optical axis of the processing laser beam emitted from 10. In this case, in the servo Z-axis direction optical head 20 and the processing head 10, the optical axes of the servo Z-axis direction laser beam and the processing laser beam are the rotation axis of the work driving device 50 (the rotation axis of the spindle motor 52). A relative positional relationship with respect to the workpiece driving device 50 is determined so as to be orthogonal to each other.

  Since the servo Z-axis direction laser light emitted from the servo Z-axis direction optical head 20 is parallel light having a diameter larger than the diameter of the workpiece OB, the laser light not blocked by the workpiece OB is processed. Incident on the objective lens 112 of the head 10. In this case, when the servo Z-axis direction laser light incident on the objective lens 112 is received, a bar-shaped shadow of the workpiece OB is formed at the center. A shadow formed by the object OB is called projection, and the projection and the surrounding light are called projection light.

  The servo Z-axis direction laser light incident on the objective lens 112 is condensed and incident on the dichroic mirror 110. The dichroic mirror 110 is an optical element that reflects light of a specific wavelength and transmits light of other wavelengths, reflects the servo laser light emitted from the laser light source 202, and emits it from the laser light source 102. The wavelength of each laser beam is set so as to transmit the processed laser beam. Accordingly, the servo Z-axis direction laser light is reflected by the dichroic mirror 110. A relay lens 116 (imaging lens) and a photodetector 118 are provided in the reflection direction of the dichroic mirror 110, and the servo Z-axis direction laser beam reflected by the dichroic mirror 110 becomes parallel light by the relay lens 116 and the photodetector 118. Is incident on the light receiving surface. On the light receiving surface of the photodetector 118, a rod-like projection that is a shadow of the object OB is projected.

  As shown in FIG. 4, the photodetector 118 includes a light receiving element in which the light receiving area is divided into left and right (Y-axis direction), and receives a detection signal proportional to the intensity of light incident on the light receiving areas A and B. Output as (a, b). This photodetector 118 is processed so that the rod-like projection S in the received servo Z-axis direction laser light (projection light L) is parallel to the dividing line DIV of the light receiving areas A and B and viewed from the Z-axis direction. When the center axis of the object OB coincides with the rotation axis of the workpiece driving device 50, the projection S of the object OB is arranged at a position that is equally divided by the dividing line DIV of the light receiving area. Therefore, the light reception signals (a, b) are shifted in the Y-axis direction from the optical axis of the machining laser beam, that is, the central axis in the X-axis direction of the workpiece OB with respect to the rotation axis of the workpiece driving device 50 due to the difference therebetween. Represents quantity.

  The light reception signals (a, b) output from the photodetector 118 are input to the Y-axis direction error signal generation circuit 161. The Y-axis direction error signal generation circuit 161 amplifies the light reception signal (a, b), calculates a difference in light intensity (ab) using this signal, and calculates the calculation result as a Y-axis direction error signal ( The result is output to the Y-axis direction servo circuit 162 as ab). The magnitude of the Y-axis direction error signal (ab) represents the amount of deviation in the Y-axis direction between the center axis of the workpiece OB and the rotation axis of the workpiece driving device 50 (the optical axis of the processing laser beam). It is.

  FIG. 5 shows the peak value of the Y-axis direction error signal (ab) when the position of the workpiece OB is changed in the Y-axis direction. As shown in the figure, the Y-axis direction error signal (ab) has an S-shaped waveform. Accordingly, in the range r (referred to as S-shaped detection range r) from the peak (c position) to the valley (a position) of the S-shaped waveform, the displacement amount of the workpiece OB in the Y-axis direction and the Y-axis direction error The magnitude of the signal (ab) corresponds to one to one. For this reason, within the S-shaped detection range r, it is possible to detect the amount of deviation of the workpiece OB in the Y-axis direction based on the Y-axis direction error signal (ab).

  For example, when the position of the processing object OB is not shifted in the Y-axis direction, the projection S projected on the photodetector 118 is located at the center of the light receiving surface as shown in FIG. ab) is zero. On the other hand, when the position of the workpiece OB is shifted to one side (referred to as the left side) in the Y-axis direction, as shown in (a), the projection S projected on the photodetector 118 is positioned on the left side of the light receiving surface. Therefore, the Y-axis direction error signal (ab) takes a negative value. When the position of the processing object OB is shifted to the other side (referred to as the right side) in the Y-axis direction, the projection S projected on the photodetector 118 is positioned on the right side of the light receiving surface as shown in (c). Therefore, the Y-axis direction error signal (ab) takes a positive value.

  The Y-axis direction servo circuit 162 starts to operate in response to a command from the controller 90, and based on the Y-axis direction error signal (ab) input from the Y-axis direction error signal generation circuit 161, the Y-axis direction error signal ( A Y-axis direction servo signal is generated so that ab) is always zero and is output to the Y-axis direction drive circuit 163. The Y-axis direction drive circuit 163 outputs a signal for driving the Y-axis actuator 114y based on the Y-axis direction servo signal, and moves the objective lens 112 in the Y-axis direction. Therefore, the position of the objective lens 112 in the Y-axis direction is controlled so that the projection projected on the photodetector 118 is maintained at the center of the light receiving surface. The movement of the objective lens 112 in the Y-axis direction moves the optical axis of the processing laser light applied to the workpiece OB in the Y-axis direction. For this reason, the position of the objective lens 112 in the Y-axis direction is maintained so that the optical axis of the processing laser beam intersects the central axis of the processing object OB.

  The servo Z-axis direction optical head 20 reflects a part (for example, 5%) of the servo laser light emitted from the laser light source 202 by the polarization beam splitter 206, and the reflected light is reflected by the condenser lens 208 to the photodetector 210. The structure which condenses on the light-receiving surface is provided. The photodetector 210 is a light receiving element that outputs a light reception signal corresponding to the intensity of light collected on the light receiving surface. Therefore, the photodetector 210 outputs a light reception signal corresponding to the intensity of the servo laser light emitted from the laser light source 202. This light reception signal is supplied to the servo Z-axis direction laser drive circuit 240.

  The servo Z-axis direction laser drive circuit 240 does not change the surface of the object to be processed OB with respect to the laser light source 202 based on a command from the controller 90, and the projected light is projected by the photodetector 118 of the processing head 10. Is a circuit for supplying a current and a voltage for emitting a servo laser beam having an intensity capable of detecting. In the present embodiment, the servo Z-axis direction laser drive circuit 240 feeds back the light reception signal output from the photodetector 210 and outputs the current output to the laser light source 202 so that the intensity of the light reception signal becomes a preset set intensity. Alternatively, the voltage is controlled. Thus, the intensity of the servo Z-axis direction laser light emitted from the servo Z-axis direction optical head 20 is maintained at a constant appropriate value.

The Y-axis direction servo signal output from the Y-axis direction servo circuit 162 is also supplied to the delay circuit 164. The delay circuit 164 starts operating in response to a command from the controller 90, delays the Y-axis direction servo signal by a time instructed by the controller 90, and outputs it to the Z-axis direction drive circuit 165 as a Z-axis direction servo signal. . This delay time is calculated by the controller 90, and is the reciprocal of the rotational speed N (times / second) around the axial direction of the workpiece OB (that is, the time 1 / N per revolution of the workpiece OB). ) Divided by “4”, the time defined by the following formula 1 (that is, the time required for 1/4 rotation of the workpiece OB).
Delay time = (1/4) · (1 / rotational speed N) Equation 1

  The Z-axis direction drive circuit 165 outputs a signal for driving the Z-axis actuator 114z based on the Z-axis direction servo signal from the delay circuit 164, and moves the objective lens 112 in the Z-axis direction. In this case, the Z-axis direction servo signal output from the delay circuit 164 is, as will be described later, the amount of deviation of the workpiece OB in the Z-axis direction, that is, the X axis of the workpiece OB relative to the rotation axis of the workpiece driving device. This represents the amount of deviation in the Z-axis direction of the central axis of the direction. Therefore, the objective lens 112 is moved in the Z-axis direction from the origin position by the amount of deviation of the workpiece OB in the Z-axis direction.

  In the processing head 10, when the objective lens 112 is at the origin position and the center axis of the processing object OB coincides with the rotation axis of the workpiece driving device 50, the focal position of the processing laser light is the processing target. Positioned to coincide with the surface of the object OB. For this reason, even if the position of the workpiece OB fluctuates in the Z-axis direction, the focal position of the machining laser beam is always machined by moving the objective lens 112 in the Z-axis direction from the origin position by the fluctuation amount. It can be made to coincide with the surface of the object OB. That is, the focal position of the processing laser beam can be maintained closer to the objective lens 112 than the rotation axis of the workpiece driving device 50 by the radius of the processing object OB.

The point that the Y-axis direction servo signal delayed by the delay circuit 164 represents the amount of deviation of the workpiece OB in the Z-axis direction will be described in detail. FIG. 7 is a view of the workpiece OB viewed from the axial direction. It is assumed that the workpiece OB indicated by the broken line has rotated about the rotation center O in the direction of the arrow to the position shown in the solid line. The rotation angle at this time is θ, the center axis position of the workpiece OB is O1, and the distance from the rotation center O to the center axis position O1 of the workpiece OB is r. Note that the one-point difference line in the figure indicates a trajectory followed by the central axis position O1 of the workpiece OB when the workpiece OB rotates once. In this case, the illustrated horizontal direction is the Y-axis direction, and the vertical direction is the Z-axis direction. With reference to the center axis position O1 of the workpiece OB at the broken line position, the Y axis direction and the Z axis with respect to the rotation center O of the center axis position O1 of the workpiece OB are rotated by the rotation angle θ of the workpiece OB. The deviation amounts Devy and Devz in the direction are expressed by the following equations 2 and 3.
Devy = r · cosθ Equation 2
Devz = r · sin θ = r · cos (θ−π / 2) Equation 3

  The deviations Devy and Devz in the Y-axis direction and the Z-axis direction are as shown in the waveform diagrams of FIGS. As is clear from these, the deviation Devz of the workpiece OB in the Z-axis direction is delayed by π / 2 with respect to the deviation Devy of the workpiece OB in the Y-axis direction. Therefore, a signal obtained by delaying the Y-axis direction servo signal from the Y-axis direction servo circuit 162 by the time required for ¼ rotation of the workpiece OB by the delay circuit 164 is a deviation amount of the workpiece OB in the Z-axis direction. Represents.

This point will be further described. Since the rotation center O of the workpiece OB is deviated from the center axis position O1 of the workpiece OB, the deviation amount Devy of the workpiece OB in the Y-axis direction is determined as follows. When the object OB rotates 1/4 in the direction of the arrow in FIG. 7, it becomes equal to the deviation Devz of the processing object OB in the Z-axis direction. Therefore, the delay circuit 164 uses the servo signal for correcting the deviation amount Devy in the Y-axis direction as the deviation amount Devy of the workpiece OB in the Y-axis direction appears as the deviation amount Devz of the workpiece OB in the Z-axis direction. It will be delayed by the time required for this. When the workpiece OB rotates in the direction opposite to the arrow direction in FIG. 7, the deviation Devz of the workpiece OB in the Z-axis direction is relative to the deviation Devy of the workpiece OB in the Y-axis direction. It is delayed by a time corresponding to 3/4 rotation of the workpiece OB. Therefore, the delay time in this case is expressed by the following equation 4.
Delay time = (3/4) · (1 / rotational speed N) Equation 4

  The controller 90 is an electronic control device including a microcomputer including a CPU, a ROM, and a RAM, a storage device such as a hard disk and a nonvolatile memory, an input / output interface, and the like. Connected to the controller 90 are an input device 91 for an operator to instruct various parameters, processing, and the like, and a display device 92 for visually informing the operator of the operation status and the like.

  Next, control when performing laser processing will be described. FIG. 6 is a flowchart showing a laser processing control routine executed by the controller 90. The laser processing control routine is stored in the ROM of the controller 90 as a control program. After setting the workpiece OB on the workpiece driving device 50, the operator performs a laser machining start instruction operation using the input device 91. Thereby, this control routine is started.

  When this control routine is activated in step S100, the controller 90 starts the operation of various circuits in step S102. Subsequently, in step S104, a command to move to the machining start position is output to the feed motor control circuit 57. In response to this command, the feed motor control circuit 57 drives the feed motor 55 while taking the movement position detected by the movement position detection circuit 58 to move the movement stage 51 to the machining start position. Subsequently, the controller 90 outputs a rotation start command to the spindle motor control circuit 56 in step S106. As a result, the spindle motor 52 is activated and the workpiece OB starts to rotate. At this time, the spindle motor control circuit 56 calculates the rotational speed of the spindle motor 52 from the number of pulses per unit time of the pulse train signal detected by the encoder 52a, and the calculated rotational speed becomes the rotational speed set by the controller 90. The rotation of the spindle motor 52 is controlled so as to be equal.

  Subsequently, in step S108, the controller 90 outputs a servo laser beam irradiation start command to the servo Z-axis direction laser drive circuit 240. Therefore, the servo Z-axis direction laser beam is irradiated from the servo Z-axis direction optical head 20 to the workpiece OB in the Z-axis direction. Further, by the irradiation of the servo laser light, the photodetector 118 outputs a light reception signal (a, b), and the Y-axis direction error signal generation circuit 161 starts to output a Y-axis direction error signal (ab).

  Subsequently, in step S110, the controller 90 outputs a servo control start command to the Y-axis direction servo circuit 162 and the delay circuit 164. Thereby, the Y-axis direction servo circuit 162 receives the Y-axis direction error signal (ab) from the Y-axis direction error signal generation circuit 161, and based on the Y-axis direction error signal (ab), the Y-axis direction error signal (ab) A Y-axis direction servo signal is generated so that the axial direction error signal (ab) is always zero, and is output to the Y-axis direction drive circuit 163. The Y-axis direction drive circuit 163 outputs a signal for driving the Y-axis actuator 114y based on the Y-axis direction servo signal, and moves the objective lens 112 in the Y-axis direction. Therefore, the position of the objective lens 112 in the Y-axis direction is controlled so that the projection projected on the photodetector 118 is maintained at the center of the light receiving surface, so that the optical axis of the processing laser beam intersects the central axis of the processing object OB. Maintained.

  On the other hand, the delay circuit 164 receives, from the controller 90, delay time data representing the time for delaying the Y-axis direction servo signal simultaneously with the servo control start instruction. The controller 90 calculates a time corresponding to ¼ rotation of the workpiece OB and outputs it to the delay circuit 164 as delay time data. The delay circuit 164 delays the Y-axis direction servo signal input from the Y-axis direction servo circuit 162 by the delay time, and outputs the delayed signal to the Z-axis direction drive circuit 165 as a Z-axis direction servo signal. The Z-axis direction drive circuit 165 outputs a signal for driving the Z-axis actuator 114z based on the Z-axis direction servo signal, and moves the objective lens 112 in the Z-axis direction. The Z-axis direction servo signal formed by delaying the Y-axis direction servo signal represents the shift amount of the workpiece OB in the Z-axis direction as described above. Therefore, the objective lens 112 is controlled to a position away from the origin position in the Z-axis direction by the amount of deviation in the Z-axis direction of the processing object OB, and the focal position of the processing laser light always matches the surface of the processing object OB. To come.

  Subsequently, in step S112, the controller 90 outputs a processing laser light irradiation start command to the processing laser drive circuit 150. In this case, the controller 90 outputs an irradiation start command in which the intensity of the processing laser light is set to a low level at which the processing object OB does not change. As a result, the processing laser drive circuit 150 drives the laser light source 102 by setting the intensity of the voltage and current supplied to the laser light source 102 to low levels. Therefore, non-machining intensity laser light is emitted from the machining head 10 toward the workpiece OB. The processing object OB is not laser-processed with respect to this non-processing intensity laser beam.

  Subsequently, in step S114, the controller 90 takes in the received light signal output from the photodetector 122 provided in the processing head 10 via the amplifier circuit 152 and the A / D converter 153, and reflects the reflected light intensity of the processing laser light. R is detected. Next, in step S116, it is determined whether or not the reflected light intensity R is greater than the lower limit value Rref. If the reflected light intensity R is greater than the lower limit value Rref, it is determined that the Z-axis direction servo control and the Y-axis direction servo control described above are normally performed, and the process proceeds to step S118. On the other hand, if the reflected light intensity R is equal to or lower than the lower limit value Rref, it is determined that the Z-axis direction servo control and the Y-axis direction servo control are not normally performed, and in step S138, the display device 92 is informed. Display, and the process proceeds to step S130.

  If the controller 90 determines “Yes” in step S116, that is, if the Z-axis direction servo control and the Y-axis direction servo control are normally performed, the controller 90 sends the processing laser drive circuit 150 in step S118. On the other hand, a command for changing the intensity of the laser light emitted from the laser light source 102 from the non-processing intensity to the processing intensity is output. As a result, the processing laser drive circuit 150 operates the laser light source 102 by switching the intensity of the voltage and current supplied to the laser light source 102 to the processing level. Therefore, from the processing head 10, a laser beam with processing intensity is emitted toward the processing object OB.

  Subsequently, the controller 90 outputs a movement start command of the moving stage 51 in the X-axis direction to the feed motor control circuit 57 in step S120. The feed motor control circuit 57 calculates the moving speed of the moving stage 51 from the number of pulses per unit time of the pulse train signal output from the encoder 55a, and drives and controls the feed motor 55 so that the calculated moving speed becomes the set speed. To do.

  Thereby, the processing object OB rotates around its central axis and moves in the X-axis direction, and the processing laser beam is irradiated on the surface thereof. Therefore, the processing object OB is irradiated with the processing laser light in a spiral shape, and a reaction trace is formed in the photoresist along the irradiation trajectory. At the same time, the Z-axis direction and the Y-axis of the objective lens 112 so that the optical axis of the processing laser beam intersects the center axis of the processing object OB and the focal position coincides with the surface of the processing object OB. The position of the direction is controlled. Accordingly, the surface of the object OB to be processed is irradiated with a vertically focused processing laser beam vertically, and a spiral reaction trace having an appropriate width is formed in the photoresist.

  Subsequently, the controller 90 takes in the movement position of the movement stage 51 detected by the movement position detection circuit 58 in step S122, and determines in step S124 whether or not the current movement position has reached the machining end position. . The processes in steps S122 and S124 are repeated until the moving position of the moving stage 51 reaches the processing end position. Therefore, during this period, as described above, laser processing and servo control of the workpiece OB are continued.

  When the moving position of the moving stage 51 reaches the processing end position, the controller 90 determines “Yes” in step S124, and in step S126, instructs the processing laser drive circuit 150 to stop irradiation of the processing laser light. Is output. Thereby, irradiation of the processing laser beam is stopped. Next, in step S128, a movement stop command for the moving stage 51 is output to the feed motor control circuit 57. As a result, energization of the feed motor 55 is stopped and the moving stage 51 is stopped. Subsequently, the controller 90 outputs a servo control stop command to the Y-axis direction servo circuit 162 and the delay circuit 164 in step S130. As a result, the Y-axis direction servo circuit 162 and the delay circuit 164 stop operating, and the Y-axis actuator 114y and the Z-axis actuator 114z stop operating. Next, in step S132, a servo laser beam irradiation stop command is output to the servo Z-axis direction laser drive circuit 240. Thereby, the irradiation of the servo Z-axis direction laser beam from the servo Z-axis direction optical head 20 is stopped.

  Subsequently, the controller 90 outputs a rotation stop command to the spindle motor control circuit 56 in step S134. Thereby, the energization to the spindle motor 52 is stopped, and the rotation of the workpiece OB is stopped. Next, in step S136, a command to move the workpiece OB to the removal position is output to the feed motor control circuit 57. Accordingly, the feed motor control circuit 57 drives the feed motor 55 while taking in the movement position detected by the movement position detection circuit 58 to move the movement stage 51 to the removal position of the workpiece OB. The operator removes the workpiece OB from the workpiece driving device 50 at this position. When the moving stage 51 is moved to the predetermined removal position in this way, the laser processing control routine is finished in step S140.

  According to the laser processing apparatus of the first embodiment described above, the Z-axis direction laser beam for servo is irradiated onto the processing object OB, and based on the position of the projection, the Y-axis direction error signal generation circuit 161, the Y-axis The direction servo circuit 162 and the Y-axis direction drive circuit 163 control the position of the objective lens 112 in the Y-axis direction, so that the position of the optical axis of the processing laser light intersects the central axis of the processing object OB. Further, the position of the objective lens 112 in the Z-axis direction is controlled by the action of the delay circuit 164 using the Y-axis direction servo signal and the Z-axis direction drive circuit 165 so that the focal position coincides with the surface of the workpiece OB. become. Therefore, even when laser processing is performed on the surface of a very thin cylindrical workpiece OB of 50 μm as in the present embodiment, the surface of the workpiece OB is irradiated with a properly focused processing laser beam. Accordingly, a spiral reaction trace having an appropriate width can be formed in the photoresist. As a result, it is possible to manufacture a pipe for producing a microspring with high accuracy.

  In the first embodiment, since the delay circuit 164 delays the Y-axis direction servo signal to form the Z-axis direction servo signal, the servo circuit for irradiating servo Y-axis direction laser light is used. The Y-axis direction optical head and the Y-axis direction light receiving device for receiving the servo Y-axis direction laser beam are not required, and the entire laser processing apparatus can be configured easily.

  In the first embodiment, the processing laser beam and the servo Z-axis direction laser beam are irradiated on the same optical axis, and the Y-axis direction error signal (a−) obtained from the light reception signal of the photodetector 118 is used. b) is fed back, and the Y-axis actuator 114y is driven by closed-loop control so that the Y-axis direction error signal (ab) is always zero. In particular, the Y-axis direction servo control can be performed with high accuracy. it can.

  Further, based on the comparison between the reflected light intensity R of the machining laser beam and the lower limit value Rref, it is determined whether or not an abnormality has occurred in the Z-axis direction servo control and the Y-axis direction servo control. Laser processing is stopped because the focal position of the laser beam for use is not appropriate. Thereby, the failure of laser processing can be prevented.

  Further, when the servo Z-axis direction laser light is emitted, the servo control in the Z-axis direction and the Y-axis direction is performed in order to control the output of the laser light source 202 so that the intensity of the light detected by the photodetector 210 becomes the set intensity. It can be performed with high accuracy.

b. Second Embodiment Next, a laser processing apparatus according to a second embodiment will be described. FIG. 9 shows a schematic configuration of the processing head 12 in the laser processing apparatus of the second embodiment. The laser processing apparatus of the second embodiment is provided with a processing head 12 in place of the processing head 10 and servo Z-axis direction optical head 20 of the laser processing apparatus of the first embodiment. Is the same as in the first embodiment. This processing head 12 has a configuration for irradiating / receiving a servo Z-axis laser beam in addition to a configuration for irradiating / receiving a processing laser beam. Hereinafter, about the structure similar to 1st Embodiment, the code | symbol same as 1st Embodiment is attached | subjected to drawing, and only a brief description is given.

  Similar to the processing head 10 of the first embodiment, the processing head 12 is configured to irradiate the processing object OB with the processing laser beam 102, the collimating lens 104, the polarization beam splitter 106, and the quarter wavelength. A plate 108, a dichroic mirror 110, and an objective lens 112 are provided, and a condenser lens 120 and a photodetector 122 are provided as a configuration for detecting the reflected light intensity of the processing laser light, and the intensity of the processing laser light emitted from the laser light source 102 is detected. The configuration includes a condensing lens 124 and a photodetector 126, and a configuration for driving the objective lens 112 in the Z-axis direction and the Y-axis direction includes a focus actuator 114 including a Z-axis actuator 114z and a Y-axis actuator 114y.

  Further, the processing head 12 includes a laser light source 130 for irradiating servo laser light, a collimating lens 132 provided along the optical axis of the servo laser light emitted from the laser light source 130, a polarization beam splitter 134 and 1 / A four-wave plate 136 is provided. The laser light source 130 is driven by the current and voltage supplied from the servo Z-axis direction laser drive circuit 240 to emit servo laser light. The servo laser light emitted from the laser light source 130 is collimated by the collimator lens 132 and enters the polarization beam splitter 134. Most of the servo laser light (for example, 95%) passes through the polarization beam splitter 134 as it is, passes through the quarter-wave plate 136, and is converted from linearly polarized light to circularly polarized light. The servo laser light that has passed through the quarter-wave plate 136 is incident on the dichroic mirror 110 provided in the optical path of the processing laser light, and is reflected there. Therefore, the servo laser beam and the processing laser beam are combined and enter the objective lens 112. In this case, the optical paths of the servo laser beam and the processing laser beam are such that the optical axis of the servo laser beam reflected by the dichroic mirror 110 and the optical axis of the processing laser beam transmitted through the dichroic mirror 110 coincide with each other. Is set.

  The servo laser light has a diameter smaller than the diameter of the processing object OB by the objective lens 112, is condensed to the same extent as the processing laser light, and is irradiated onto the surface of the processing object OB in a spot shape. The servo laser beam irradiated on the workpiece OB is the servo Z-axis direction laser beam. The machining laser beam and the servo Z-axis direction laser beam are reflected by the surface of the workpiece OB, enter the objective lens 112, and are returned to parallel light. In this case, the processing laser light passes through the dichroic mirror 110 as it is, but the servo Z-axis direction laser light is reflected by the dichroic mirror 110. Therefore, the machining laser beam and the servo Z-axis direction laser beam are separated by the dichroic mirror 110.

  The servo Z-axis direction laser light reflected by the dichroic mirror 110 passes through the quarter-wave plate 136. In this case, the servo Z-axis direction laser light (reflected light) has passed through the quarter-wave plate twice, so that the polarization direction differs from the laser light emitted from the laser light source 130 by 90 degrees. It becomes. Therefore, the servo Z-axis direction laser light is reflected by the polarization beam splitter 134.

  A photodetector 140 is provided in the reflection direction of the polarization beam splitter 134. Therefore, the servo Z-axis direction laser light reflected from the surface of the workpiece OB is incident on the photodetector 140. Similar to the photodetector 118 of the first embodiment, the photodetector 140 includes two light receiving elements in which the light receiving area is divided into left and right (Y-axis direction), and the intensity of light incident on the light receiving areas A and B is adjusted. A proportional detection signal is output as a light reception signal (a, b). Further, when the objective lens 112 is at the origin position and the center axis of the workpiece OB coincides with the rotation axis of the workpiece driving device 50 when the objective lens 112 is at the origin position, the photodetector 140 is in FIG. 2), the servo Z-axis direction laser beam is arranged at a position that is divided into two equal parts by the dividing line DIV of the light receiving region. Therefore, this light reception signal (a, b) also shifts in the Y-axis direction from the optical axis of the machining laser beam, that is, the central axis in the X-axis direction of the workpiece OB with respect to the rotation axis of the workpiece driving device 50 due to the difference therebetween. Represents quantity.

  The received light signals (a, b) output from the photodetector 140 are input to the Y-axis direction error signal generation circuit 161 as in the first embodiment. The Y-axis direction error signal generation circuit 161 amplifies the light reception signal (a, b), calculates a difference in light intensity (ab) using this signal, and calculates the calculation result as a Y-axis direction error signal ( The result is output to the Y-axis direction servo circuit 162 as ab). When the position of the workpiece OB fluctuates in the Y-axis direction, as shown in FIGS. 10A, 10B, and 10C, the servo Z-axis irradiated to the workpiece OB according to the fluctuating position. The position of the directional laser beam changes, and accordingly, the position of the reflected light RL received by the photodetector 140 changes. For this reason, the magnitude of the Y-axis direction error signal (ab) is the amount of deviation in the Y-axis direction between the center axis of the workpiece OB and the rotation axis of the workpiece driving device 50 (the optical axis of the processing laser beam). It represents.

  The operations of the Y-axis direction servo circuit 162 and the Y-axis direction drive circuit 163 are the same as in the first embodiment. That is, the Y-axis direction error signal (ab) is always zero based on the Y-axis direction error signal (ab) input from the Y-axis direction error signal generation circuit 161 by the Y-axis direction servo circuit 162. The Y-axis direction servo signal is generated, and the Y-axis direction drive circuit 163 outputs a drive signal to the Y-axis actuator 114y based on the Y-axis direction servo signal to move the objective lens 112 in the Y-axis direction. Therefore, the position of the objective lens 112 in the Y-axis direction is controlled so that the reflected light of the servo Z-axis laser beam received by the photodetector 140 is maintained at the center of the light-receiving surface. For this reason, the optical axis of the processing laser light is maintained so as to intersect the central axis of the processing object OB.

  The processing head 12 further reflects a part (for example, 5%) of the servo laser light emitted from the laser light source 130 by the polarization beam splitter 134 and receives the reflected light from the photodetector 144 by the condenser lens 142. A configuration for condensing light onto the surface is provided. The photodetector 144 outputs a light reception signal corresponding to the intensity of the servo laser light emitted from the laser light source 130, as with the photodetector 210 of the first embodiment. This light reception signal is supplied to the servo Z-axis direction laser drive circuit 240. The servo Z-axis direction laser drive circuit 240 feeds back the light reception signal output from the photodetector 144 and adjusts the output of the laser light source 130 so that the intensity of the light reception signal becomes a preset intensity. As a result, the intensity of servo Z-axis direction laser light emitted from the processing head 12 toward the processing object OB is maintained at a constant appropriate value.

  Moreover, the laser processing apparatus of 2nd Embodiment performs the laser processing control routine similar to 1st Embodiment.

  In the laser processing apparatus according to the second embodiment described above, servo laser light in the Z-axis direction is condensed by the processing head 12 and applied to the processing object OB, and the processing laser is based on the position of the reflected light. The position of the objective lens 112 in the Y-axis direction is controlled so that the position of the optical axis of the light intersects the central axis of the workpiece OB. Further, the delay circuit 164 and the Z-axis direction drive circuit 165 use the Y-axis direction servo signal from the Y-axis direction servo circuit 162 so that the focal position of the processing laser beam coincides with the surface position of the processing object OB. The position of the objective lens 112 in the Z-axis direction is controlled. Therefore, the same effects as those of the first embodiment are obtained. Further, the detection position of the reflected light of the servo Z-axis direction laser beam greatly varies with respect to the displacement of the workpiece OB in the Y-axis direction, so that Y-axis direction servo control can be performed with high accuracy.

  The first and second 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. is there.

  In the first embodiment, the servo Z-axis direction laser beam is received by the photodetector 118 via the objective lens 112 for condensing the processing laser beam, but the servo Z-axis direction laser beam is used. The optical axis of the light may be slightly shifted from the optical axis of the processing laser light, and the servo Z-axis direction laser light may be received by a photodetector provided in the vicinity of the objective lens 112. In this configuration, the variation of the processing object OB is detected in the vicinity of the focal position of the processing laser beam. However, if the variation of the processing object OB is not large, servo control is possible.

  In each of the above embodiments, the Y-axis direction servo signal from the Y-axis direction servo circuit 162 is guided to the delay circuit 164, and the delay circuit 164 generates the Z-axis direction servo signal. However, instead of this, as shown by the broken line in FIG. 1, the drive signal output from the Y-axis direction drive circuit 163 is input to the delay circuit 164, and the delay circuit 164 sends the drive signal to each of the above-described embodiments. Similarly to the embodiment, the Z-axis direction servo signal may be generated with a delay. Further, in the case of a configuration in which the optical axis of the servo Z-axis direction laser light is slightly shifted from the optical axis of the processing laser light, and the servo Z-axis direction laser light is received by a photodetector provided in the vicinity of the objective lens 112, Since the servo control is open loop control, the error signal may be delayed. That is, the delay circuit 164 inputs the Y-axis direction error signal (ab) output from the Y-axis direction error signal generation circuit 161 to the delay circuit 164, and the delay circuit 164 outputs the Y-axis direction error signal (ab). Is delayed in the same manner as in the above embodiments. Then, a Z-axis direction servo circuit similar to the Y-axis direction servo circuit 162 is newly provided, and the Z-axis direction servo circuit generates a Z-axis direction servo signal using the delayed Y-axis direction error signal (ab). It may be generated and supplied to the Z-axis direction drive 165.

  Further, when the servo control is open loop control, the light reception signal used when generating the error signal may be delayed. That is, as indicated by broken lines in FIG. 1, the light reception signal (a, b) output from the photodetector 118 is input to the delay circuit 164, and the delay circuit 164 converts the light reception signal (a, b) Delay as in the embodiment. Then, a Z-axis direction error signal generation circuit and a Z-axis direction servo circuit similar to the Y-axis direction error signal generation circuit 161 and the Y-axis direction servo circuit 162 are newly provided, and the Z-axis direction error signal generation circuit is delayed. A Z-axis direction error signal is generated by using the received light signals (a, b), and a Y-axis direction servo circuit generates a Z-axis direction servo signal by using the generated Z-axis direction error signal. 165 may be supplied.

  In each of the above embodiments, the focal position of the processing laser beam is controlled to be an appropriate position of the processing object OB only by driving the objective lens 112 by the actuator 114. However, a displacement sensor is provided to the Y-axis actuator 114y. And detecting the DC component (offset part) of the signal output from the displacement sensor, and moving the machining head and servo Z-axis direction optical head integrally in the Y-axis direction so that the DC component becomes zero. An actuator may be provided separately. In this case, since the objective lens 112 is driven around the origin position, servo control with higher accuracy can be performed. The DC component of the signal output from the Y-axis direction servo circuit 162 or the delay circuit 168 may be detected without providing a displacement sensor in the Y-axis actuator 114y.

  Further, in each of the above embodiments, in order to move the irradiation position of the processing laser light in the X-axis direction relative to the processing object OB, the work driving device 50 moves the processing object OB in the X-axis direction. Moved. However, instead of this, the object OB is fixed, and the unit in which the machining head 10 and the servo Z-axis direction optical head 20 (or the machining head 12) are integrated is moved in the X-axis direction. Also good. Further, both the processing object OB and the unit in which the processing head 10 and the servo Z-axis direction optical head 20 (or the processing head 12) are integrated may be moved simultaneously in the X-axis direction. .

  In each of the above embodiments, the processing object OB is rotated around its central axis in order to rotate the irradiation position of the processing laser light relative to the processing object OB around the X-axis direction. . However, instead of this, a unit in which the workpiece OB is fixed and the machining head 10 and the servo Z-axis direction optical head 20 (or the machining head 12) are integrated around the central axis of the workpiece OB. It may be rotated. Further, both the processing object OB and the unit in which the processing head 10 and the servo Z-axis direction optical head 20 (or the processing head 12) are integrated may be rotated simultaneously around the X-axis direction.

  Moreover, in each said embodiment, although the process target OB is being fixed toward the horizontal direction, the direction which fixes the process target OB can be set to arbitrary directions. Along with this, the direction of the processing laser beam and the servo Z-axis direction laser beam can be arbitrarily set under conditions satisfying the relationship between the X-axis, Y-axis, and Z-axis directions.

DESCRIPTION OF SYMBOLS 10,12 ... Machining head, 20 ... Z-axis direction optical head, 50 ... Work drive device, 51 ... Moving stage, 52 ... Spindle motor, 90 ... Controller, 102, 130, 202 ... Laser light source, 112 ... Objective lens, 114: Focus actuator, 118, 122, 126, 140, 144, 210 ... Photo detector, 150 ... Laser drive circuit for processing, 161 ... Y-axis direction error signal generation circuit, 162 ... Y-axis direction servo circuit, 164 ... Delay circuit, 240 ... Z-axis direction laser drive circuit for servo

Claims (4)

An object support means for supporting a cylindrical workpiece having a small diameter with its central axis direction as the X-axis direction;
A Z-axis having a processing laser light source and an objective lens, and processing laser light emitted from the processing laser light source and condensed by the objective lens on the surface of the processing object orthogonal to the X-axis direction A laser beam irradiating means for irradiating from a direction;
A Y-axis actuator that moves the optical axis of the processing laser light in the Y-axis direction by displacing the objective lens in a Y-axis direction orthogonal to the X-axis direction and the Z-axis direction;
A Z-axis actuator that displaces the objective lens in the Z-axis direction and moves a focal position of the processing laser light in the Z-axis direction;
The processing object or the processing laser light irradiation means is rotated about the X-axis direction, and the irradiation position of the processing laser light on the processing object is relatively set with respect to the processing object. Rotating means for rotating around the direction;
By displacing the processing object or the processing laser light irradiation means in the X-axis direction, the irradiation position of the processing laser light on the processing object is set relative to the processing object in the X-axis direction. In a laser processing apparatus provided with a moving means for moving to
Servo laser beam irradiation means for irradiating a workpiece with a servo laser beam whose irradiation direction is set in the Z-axis direction;
A laser beam generated based on the servo laser beam and including information representing the position of the workpiece in the Y-axis direction is received, and the X of the workpiece relative to the optical axis of the machining laser beam is received. A shift detection photodetector that outputs a light receiving signal representing a shift amount in the Y-axis direction of the central axis in the axial direction;
A control signal for causing the optical axis of the laser beam for processing to intersect the central axis in the X-axis direction of the processing object is generated using the light reception signal output from the photodetector for detecting deviation, and the control signal And a Y-axis direction servo control means for driving and controlling the Y-axis actuator to cross the optical axis of the processing laser light with the central axis in the X-axis direction of the workpiece.
The light reception signal output from the deviation detection photodetector or the control signal generated by the Y-axis direction servo control means is input, and the deviation in the Y-axis direction is the X of the irradiation position of the processing laser beam by the rotation means. With the relative rotation around the axial direction, the input light reception signal or control signal is delayed by the time required for appearing as a deviation in the Z axis direction, and the Z axis actuator is delayed using the delayed light reception signal or control signal. And a Z-axis direction servo control means for adjusting the focal position of the processing laser beam to the outer peripheral surface of the workpiece. The laser processing apparatus according to claim 1,
The servo laser beam irradiation means uses a parallel laser beam having a diameter larger than the diameter of the object to be processed as the servo laser beam, and the processing laser beam and the optical axis emitted from the processing laser beam irradiation unit are Irradiate the object to be processed from the opposite position to the irradiation direction of the laser beam for processing at the same position,
The shift detection photodetector receives a laser beam including a projection of the workpiece,
The processing laser beam irradiating means separates the servo laser beam incident on the optical path from the optical path in the middle of the optical path for irradiating the processing laser beam to the processing object, and detects the deviation. A laser processing apparatus comprising a separation optical element that leads to a laser beam. The laser processing apparatus according to claim 1,
The servo laser beam irradiation means uses the laser beam condensed by the objective lens as much as the processing laser beam as the servo laser beam at a position coaxial with the processing laser beam. And the deviation detection photodetector receives the reflected light of the servo laser light from the workpiece,
The processing laser light irradiation means separates reflected light of the servo laser light from the processing target from the optical path in the middle of an optical path for irradiating the processing laser light on the processing target. A laser processing apparatus comprising a separation optical element that leads to a photodetection detector for deviation detection. The laser processing apparatus according to any one of claims 1 to 3, further comprising:
An intensity detection photodetector that receives the reflected light of the processing laser light irradiated on the surface of the object to be processed by the processing laser light irradiation means, and outputs a received light signal indicating the intensity of the reflected light;
When the light reception signal output from the intensity detection photodetector is input and the intensity of the reflected light represented by the input light reception signal is equal to or less than a reference value, it is determined that the focal position of the processing laser light is not appropriate. A laser processing apparatus comprising: a determination unit configured to perform determination.

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