JP2010279953A - Laser beam machining apparatus, and focus servo control method of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control the focal point of laser beam so as to become the appropriate position of an object OB to be machined even when performing the laser beam machining of the surface of the cylindrical tubular object OB of very small diameter. <P>SOLUTION: Laser beam for machining is applied to the cylindrical tubular object OB extending in X-axis direction in Z-axis direction from a machining head 10, and laser beam in Z-axis direction for servo is applied in Z-axis direction from a Z-axis direction beam head 20 for servo, and laser beam in Y-axis direction for servo is applied in Y-axis direction from a Y-axis direction beam head 30 for servo. The deviation in the Y-axis direction of the object OB is detected by the position of the projection of the object OB to be reflected on a photo detector 118. The deviation in the Z-axis direction of the object OB is detected by the position of the projection of the object OB to be reflected on a photo detector 402. <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 pipe-shaped object, and a focus servo control method that adjusts the focal position of laser light in the laser processing apparatus to an appropriate position of the object to be processed.

  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, for example.

  In a drum type laser processing apparatus, when performing fine laser processing on an object to be processed, for example, as proposed in Patent Document 2, the reflected light from the object to be processed is similar to focus servo control in an optical disk apparatus. A focus error corresponding to a deviation in the optical axis direction between the focal position of the laser beam and the surface of the object to be processed from the light reception signal of each light reception area by a photo detector having a light reception area divided into four, and using an astigmatism method or the like Generate a 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 laser beam can be irradiated perpendicularly to the surface of the workpiece. However, when the workpiece is a very thin cylindrical pipe (for example, a cylindrical pipe having a diameter of 50 μm). Generates an appropriate focus error signal because the laser beam is obliquely applied to the surface of the workpiece when the optical axis of the laser beam is deviated from the central axis of the cylindrical pipe (does not intersect). I can't. 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 focal point of the laser beam is at an appropriate position of the workpiece.

  The present invention has been made to cope with the above problem, and even when the surface of a cylindrical pipe-shaped workpiece having a very small diameter is subjected to laser machining, the focus of the laser beam is appropriate for the workpiece. The purpose is to control the position.

  In order to achieve the above object, the laser processing apparatus according to the present invention is characterized in that a cylindrical pipe-shaped workpiece is rotated around its central axis relative to a workpiece around the workpiece. And a laser beam for processing is condensed by an objective lens, and the surface of the processing object is irradiated in a Z-axis direction perpendicular to the X-axis direction that is the central axis direction of the processing object. In a laser processing apparatus comprising: a processing laser light irradiation means for performing laser processing; and a processing laser light irradiation position moving means for moving an irradiation position of the processing laser light applied to the processing object in the X-axis direction. Servo Z-axis laser light whose irradiation direction is set in the Z-axis direction, and servo Y whose irradiation direction is set in the Y-axis direction perpendicular to the Z-axis direction and the X-axis direction Processing with axial laser light Servo laser light irradiating means for irradiating an object, and projection or reflected light of the object to be processed of the servo Z-axis direction laser light irradiated in the Z-axis direction received on the light-receiving surface, A Z-axis direction laser beam detecting means for outputting a received light signal corresponding to the position of the projection or reflected light, and a projection or reflected light of the workpiece of the servo Y-axis direction laser beam irradiated in the Y-axis direction. Based on the Y-axis direction laser light detecting means that receives the light receiving surface and outputs a light receiving signal corresponding to the position of the projection or reflected light on the light receiving surface, and the light receiving signal output from the Z-axis direction laser light detecting means. Y-axis direction servo means for driving the objective lens in the Y-axis direction so that the optical axis of the processing laser light intersects the central axis of the object to be processed, and the Y-axis direction laser light detection means And a Z-axis direction servo means for driving the objective lens in the Z-axis direction so that the focal position of the processing laser beam coincides with the surface of the object to be processed based on the received light-receiving signal. .

  In the present invention, the processing laser beam irradiating means condenses the processing laser beam with the objective lens while rotating the cylindrical pipe-shaped processing object around its central axis by the rotating means, and is applied to the surface of the processing object. Irradiate. At the same time, the processing laser light irradiation position moving means moves the processing laser light irradiation position in the direction of the central axis of the processing object. Thereby, the surface of the workpiece is laser-processed in a spiral shape. For example, fine pits (intermittently formed grooves), continuous grooves, or reaction traces (forms that change depending on the developer) are formed in a spiral on the surface of the workpiece. The

  In the present invention, the central axis direction of the workpiece is the X-axis direction, the direction perpendicular to the X-axis direction and the laser beam for machining is irradiated onto the workpiece is the Z-axis direction, the X-axis direction and the Z-axis direction. The direction perpendicular to both of these is defined as the Y-axis direction. Therefore, the irradiation position of the processing laser light moves in the X-axis direction. In moving the irradiation position in the X-axis direction, the workpiece may be moved in the X-axis direction, or the processing laser beam may be moved in the X-axis direction.

  In general, when performing laser processing, the reflected light of the processing laser light is received to generate a focus error signal, and the objective lens is driven in the optical axis direction so that the focal position coincides with the surface of the processing object. In the present invention, since the object to be processed is a cylindrical pipe, if the diameter of the object to be processed is very thin, if the optical axis of the processing laser beam deviates to a position that does not intersect the center axis of the object to be processed, The focus error signal cannot be properly generated from the reflected light of the laser beam for use. Therefore, the present invention irradiates the processing target object with a non-processing intensity servo laser beam in the Z-axis direction and the Y-axis direction at the detection position of the projected or reflected light. Based on this, the objective lens is driven in the Z-axis direction and the Y-axis direction to perform focus servo control.

  The servo laser light irradiation means irradiates the workpiece with servo laser light (servo Z-axis laser light and servo Y-axis laser light) from two directions, the Z-axis direction and the Y-axis direction. To do. The servo Z-axis direction laser light and the servo Y-axis direction laser light are not limited to those emitted from separate laser light sources, but the laser light emitted from one laser light source is separated and the Z-axis direction and the Y-axis are separated. It may be irradiated in the direction.

  The Z-axis direction laser beam detecting means receives the projection or reflected light of the processing object of the servo Z-axis direction laser beam on the light receiving surface, and outputs a received light signal corresponding to the position of the projected or reflected light on the light receiving surface. The Y-axis direction servo means drives the objective lens in the Y-axis direction so that the optical axis of the processing laser light intersects the central axis of the object to be processed based on the received light signal output from the Z-axis direction laser light detecting means. To do. For example, if a parallel laser beam having a diameter larger than the diameter of the workpiece is used as the servo Z-axis laser beam, a rod-like projection of the workpiece is projected on the light receiving surface of the Z-axis laser beam detecting means. The position of the projection corresponds to the position of the workpiece in the Y-axis direction. Further, if a laser beam condensed to a diameter smaller than the diameter of the workpiece is used as the servo Z-axis direction laser beam, a laser spot is formed on the surface of the workpiece, and the center axis position of the workpiece is When the laser beam deviates from the optical axis, the reflection direction of the laser beam fluctuates accordingly. Therefore, the position of the reflected light received on the light receiving surface of the Z-axis direction laser beam detection means is Y of the workpiece. It corresponds to the position in the axial direction. Utilizing this fact, the Y-axis direction servo means drives the objective lens in the Y-axis direction based on the position where the projection or reflected light is detected. As a result, even if the object to be processed fluctuates in the Y-axis direction during laser processing, the optical axis of the processing laser light intersects with the center axis of the object to be processed. That is, the irradiation position in the Y-axis direction of the processing laser beam is appropriate.

  Similarly, the Y-axis direction laser beam detecting means receives the projection or reflected light of the workpiece of the servo Y-axis direction laser beam on the light receiving surface, and receives a received light signal corresponding to the position of the projected or reflected light on the light receiving surface. Output. The Z-axis direction servo means drives the objective lens in the Z-axis direction so that the focal position of the processing laser light coincides with the surface of the object to be processed based on the light reception signal output from the Y-axis direction laser light detection means. . For example, if a parallel laser beam having a diameter larger than the diameter of the workpiece is used as the servo Y-axis laser beam, a rod-like projection of the workpiece is projected on the light receiving surface of the Y-axis laser beam detector. The projected position corresponds to the position of the workpiece in the Z-axis direction. Further, if a laser beam condensed to a diameter smaller than the diameter of the workpiece is used as the servo Y-axis laser beam, a laser spot is formed on the surface of the workpiece, and the central axis position of the workpiece is When the laser beam deviates from the optical axis, the reflection direction of the laser beam fluctuates accordingly. Therefore, the position of the reflected light received by the light receiving surface of the Y-axis direction laser beam detection means is Z of the workpiece. It corresponds to the position in the axial direction. Utilizing this fact, the Z-axis direction servo means drives the objective lens in the Z-axis direction based on the position where the projected or reflected light is detected. As a result, even if the object to be processed fluctuates in the Z-axis direction during laser processing, the focal position of the processing laser light coincides with the surface of the object to be processed.

  As a result, in the present invention, even when the diameter of the workpiece is very small, it is possible to irradiate the processing laser beam to an appropriate position on the surface of the workpiece, and to process the workpiece satisfactorily. can do. In particular, this is effective for a fine cylindrical pipe-shaped workpiece having a diameter of 100 μm or less.

  Another feature of the laser processing apparatus according to the present invention is that the servo laser light irradiation means applies the parallel laser light having a diameter larger than the diameter of the processing object to the processing object as servo Z-axis direction laser light. Z axis direction irradiation means for irradiating in the Z axis direction, and Y axis for irradiating the workpiece in the Y axis direction with a parallel laser beam having a diameter larger than the diameter of the workpiece as a servo Y axis direction laser beam. Direction irradiation means, wherein the Z-axis direction laser light detection means receives a projection of the workpiece of the servo Z-axis direction laser light on a light receiving surface, and corresponds to the position of the projection on the light receiving surface A light reception signal is output, and the Y-axis direction laser light detection means receives the projection of the workpiece of the servo Y-axis direction laser light on a light receiving surface, and receives light according to the position of the projection on the light receiving surface. Output signal In the Rukoto.

  In the present invention, the Z-axis direction irradiation means irradiates the workpiece in the Z-axis direction with a parallel laser beam having a diameter larger than the diameter of the workpiece as a servo Z-axis direction laser beam. The Z-axis direction laser beam detecting means receives the projection of the workpiece of the servo Z-axis direction laser beam on the light receiving surface and outputs a light reception signal corresponding to the position of the projection on the light receiving surface. For example, in the Z-axis direction laser beam detecting means, the light receiving region is divided in the direction in which the rod-like projection of the workpiece of the servo Z-axis direction laser beam moves in accordance with the position variation of the workpiece in the Y-axis direction. A Z-axis laser light detector having a light receiving surface may be provided. When the difference in the magnitude (light intensity) of the light receiving signal in the divided light receiving areas is obtained, the light receiving is increased as the formation position of the projection of the workpiece on the Z-axis laser light detector is farther from the center of the light receiving surface. The difference in signal output increases. Therefore, the difference in the received light signal output corresponds to the positional relationship in the Y-axis direction between the optical axis of the processing laser beam and the central axis of the workpiece. Utilizing this fact, the Y-axis direction servo means drives the objective lens in the Y-axis direction based on the light reception signal output from the Z-axis direction laser light detection means. As a result, the optical axis of the processing laser beam intersects the central axis of the processing object.

  On the other hand, the Y-axis direction irradiation means irradiates the workpiece in the Y-axis direction with a parallel laser beam having a diameter larger than the diameter of the workpiece as servo Y-axis laser beam. The Y-axis direction laser light detecting means receives the projection of the workpiece of the servo Y-axis direction laser light on the light receiving surface and outputs a light reception signal corresponding to the position of the projection on the light receiving surface. For example, in the Y-axis direction laser beam detecting means, the light receiving region is divided in the direction in which the rod-like projection of the workpiece of the servo Y-axis direction laser beam moves according to the position variation of the workpiece in the Z-axis direction. A Y-axis direction laser beam detector having a light receiving surface may be provided. When the difference in the magnitude (light intensity) of the light receiving signal in the divided light receiving area is obtained, the light receiving is increased as the formation position of the projection of the workpiece on the Y-axis direction laser light detector is farther from the center of the light receiving surface. The difference in signal output increases. Therefore, the difference in the received light signal output corresponds to the positional relationship in the Z-axis direction between the focal position of the processing laser beam and the surface of the processing object. Utilizing this fact, the Z-axis direction servo means drives the objective lens in the Z-axis direction based on the light reception signal output from the Y-axis direction laser light detection means. Thereby, the focal position of the processing laser beam coincides with the surface of the processing object.

  Thus, according to the present invention, since the objective lens is driven based on the detection position of the projection of the workpiece in the two directions of the Z-axis direction and the Y-axis direction, the position of the workpiece is the X-axis direction. Even if it fluctuates in the Y-axis direction, it is possible to easily irradiate the processing laser beam to the appropriate position on the surface of the processing target, and to process the processing target satisfactorily.

  Another feature of the laser processing apparatus of the present invention is that the Z-axis direction irradiating means has the same optical axis as the processing laser light irradiated from the processing laser light irradiating means. And irradiating the processing object from a direction opposite to the irradiation direction of the processing laser light, and the processing laser light irradiating means applies the processing laser light to the processing object. In the middle of the optical path for irradiating, a separation optical element for separating the servo Z-axis direction laser light incident on the optical path from the optical path and guiding it to the light receiving surface of the Z-axis direction laser light detection means is provided. is there.

  In the present invention, a machining laser beam and a servo Z-axis direction laser beam are irradiated on a workpiece on the same optical axis, and the servo Z-axis direction laser beam is used for machining. It detects separately from the optical path of a laser beam. Therefore, since the optical axes of the machining laser beam and the servo Z-axis direction laser beam coincide with each other, the received light signal of the Z-axis direction laser beam detecting means is always fed back to process the servo Z-axis direction laser beam. The objective lens can be driven in the Y-axis direction so as to intersect the central axis of the object. For this reason, the accuracy of the Y-axis direction servo means is improved. For example, the Z-axis direction laser light detection means is a light-receiving surface in which the light-receiving area is divided in the direction in which the projection of the processing object of the servo Z-axis direction laser light moves according to the position variation of the processing object in the Y-axis direction. A Z-axis direction laser light detector having Then, the Y-axis direction servo means drives the objective lens in the Y-axis direction by closed-loop control so that the difference in the magnitude (light intensity) of the received light signal in the divided light-receiving area becomes zero, The optical axis of the laser beam for processing can be crossed with the central axis of the processing object with high accuracy.

  Another feature of the laser processing apparatus of the present invention is that the servo laser beam irradiation means uses the laser beam condensed to the same extent as the processing laser beam by the objective lens as the servo Z-axis direction laser beam. Z-axis direction irradiating means for irradiating the object to be processed in the Z-axis direction at a position coaxial with the laser beam for use, and parallel laser light having a diameter larger than the diameter of the object to be processed for servo Y-axis direction laser light Y-axis direction irradiating means for irradiating the object to be processed in the Y-axis direction, and the Z-axis direction laser light detecting means receives reflected light of the object to be processed of the servo Z-axis direction laser light. The Y-axis direction laser light detecting means receives the projection of the workpiece of the servo Y-axis direction laser light received by the surface and outputs a light reception signal corresponding to the position of the reflected light on the light receiving surface. In the face Serial is to output a light reception signal corresponding to the position of the projection on the light receiving surface.

  In the present invention, the Z-axis direction irradiation means converts the laser beam condensed by the objective lens to the same extent as the processing laser beam as a servo Z-axis direction laser beam at a position coaxial with the processing laser beam. Irradiate in the Z-axis direction. The Z-axis direction laser beam detection means receives the reflected light of the servo Z-axis direction laser beam from the workpiece and outputs a received light signal corresponding to the position of the reflected light on the light-receiving surface. For example, the Z-axis direction laser light detection means is a light-receiving region in which the light-receiving region is divided in the direction in which the reflected light of the processing object of the servo Z-axis direction laser light moves in accordance with the position variation of the processing object in the Y-axis direction. A Z-axis laser light detector having a surface may be provided. When the difference in the magnitude (light intensity) of the light receiving signal of the divided light receiving areas is obtained, the light receiving position of the reflected light of the workpiece to be detected by the Z-axis laser light detector is further away from the center of the light receiving surface. The difference in the received light signal output increases. Therefore, the difference in the received light signal output corresponds to the positional relationship in the Y-axis direction between the optical axis of the processing laser beam and the central axis of the workpiece. Utilizing this fact, the Y-axis direction servo means drives the objective lens in the Y-axis direction based on the light reception signal output from the Z-axis direction laser light detection means. As a result, the optical axis of the processing laser beam intersects the central axis of the processing object.

  On the other hand, the Y-axis direction irradiation means irradiates the workpiece in the Y-axis direction with a parallel laser beam having a diameter larger than the diameter of the workpiece as servo Y-axis laser beam. The Y-axis direction laser light detecting means receives the projection of the workpiece of the servo Y-axis direction laser light on the light receiving surface and outputs a light reception signal corresponding to the position of the projection on the light receiving surface. For example, in the Y-axis direction laser beam detecting means, the light receiving region is divided in the direction in which the rod-like projection of the workpiece of the servo Y-axis direction laser beam moves according to the position variation of the workpiece in the Z-axis direction. A Y-axis direction laser beam detector having a light receiving surface may be provided. When the difference in the magnitude (light intensity) of the light receiving signal in the divided light receiving area is obtained, the light receiving is increased as the formation position of the projection of the workpiece on the Y-axis direction laser light detector is farther from the center of the light receiving surface. The difference in signal output increases. Therefore, the difference in the received light signal output corresponds to the positional relationship in the Z-axis direction between the focal position of the processing laser beam and the surface of the processing object. Utilizing this fact, the Z-axis direction servo means drives the objective lens in the Z-axis direction based on the light reception signal output from the Y-axis direction laser light detection means. Thereby, the focal position of the processing laser beam coincides with the surface of the processing object.

  As described above, according to the present invention, the objective lens is driven based on the detection position of the reflection of the servo Z-axis direction laser beam reflected from the workpiece and the projection of the servo target Y-axis direction laser beam. Therefore, even if the position of the processing object fluctuates in the X-axis direction and the Y-axis direction, it is possible to easily irradiate the processing laser beam to the appropriate position on the surface of the processing object, and to improve the processing object. Can be processed.

  Another feature of the laser processing apparatus of the present invention is that the Z-axis direction servo means is a relay lens that is movable in a direction perpendicular to the optical path of the incident light path to the light receiving surface of the Y-axis direction laser light detecting means. And the projection of the workpiece of the servo Y-axis direction laser light at the center of the light-receiving surface of the Y-axis direction laser light detection means based on the light-receiving signal output from the Y-axis direction laser light detection means The relay lens is driven so as to be positioned, and the objective lens is driven in the Z-axis direction together with the driving of the relay lens.

  In the present invention, the Z-axis direction servo means receives the Y-axis direction laser light reception based on the light-receiving signal output from the Y-axis direction laser light detection means. A relay lens (for example, an imaging lens) is driven so as to be positioned at the center of the light receiving surface of the means. When the relay lens is moved in the direction perpendicular to the optical axis, the projection of the workpiece of the servo Y-axis direction laser light projected on the light receiving surface of the Y-axis direction laser light detection means is moved accordingly. Therefore, the Z-axis direction servo means feeds back the projection position of the workpiece of the servo Y-axis direction laser light so that the projection is positioned at the center of the light receiving surface of the Y-axis direction laser light detection means. Can be controlled.

  For example, a Y-axis direction laser beam having a light-receiving surface in which a light-receiving area is divided in a direction in which a rod-like projection of the processing target object of the servo Y-axis direction laser beam moves in accordance with a change in position of the workpiece in the Z-axis direction A detector is provided, and the Z-axis direction servo means may drive the relay lens by closed loop control so that the difference in the magnitude of the received light signal (light intensity) in the divided light receiving area becomes zero.

  The Z-axis direction servo means drives the objective lens in the Z-axis direction together with the driving of the relay lens, thereby matching the focal position of the processing laser light with the surface of the processing object. As a result, the accuracy of the Z-axis direction servo means is improved, and the focal position adjustment range in the Z-axis direction of the processing laser beam can be widened.

  Another feature of the laser processing apparatus of the present invention is that the Y-axis direction irradiating means applies parallel laser light having a diameter larger than the diameter of the processing object to the processing object as a first servo Y-axis direction laser light. First Y-axis direction irradiating means for irradiating in the Y-axis direction, and laser light condensed to a diameter smaller than the diameter of the object to be processed as second servo Y-axis direction laser light to the object to be processed to the Y-axis Second Y-axis direction irradiating means for irradiating in the direction, and the Y-axis direction laser light detecting means is a first servo Y-axis direction laser light irradiated by the first Y-axis direction irradiating means. A first Y-axis direction laser light detector that receives the projection on the light-receiving surface and outputs a light-receiving signal corresponding to the position of the projection on the light-receiving surface, and a second servo Y irradiated by the second Y-axis direction irradiation means Before the axial laser beam A second Y-axis direction laser beam detector that receives the reflected light of the object to be processed on the light-receiving surface and outputs a light-receiving signal corresponding to the position of the reflected light on the light-receiving surface, and the Z-axis direction servo means includes: A relay lens that is movable in a direction perpendicular to the optical path in a common incident optical path of the first Y-axis direction laser light detector and the second Y-axis direction laser light detector, and the first servo Y-axis direction The relay lens is driven so that the projection of the processing object of the laser light is positioned at the center of the light receiving surface of the first Y-axis direction laser light detector, and the objective lens is moved to Z together with the driving of the relay lens. The first Z-axis servo means for driving in the axial direction and the reflected light of the workpiece of the second servo Y-axis laser light are positioned at the center of the light receiving surface of the second Y-axis laser light detector. To the above A second Z-axis servo unit that drives the lens and drives the objective lens in the Z-axis direction in conjunction with the driving of the relay lens; and the second Z-axis servo unit after the first Z-axis servo unit operates. And an operation switching means for switching the operation so that the means operates.

  In the present invention, two servo laser beams are used as the servo Y-axis direction laser beams. The first Y-axis direction irradiating unit irradiates the workpiece in the Y-axis direction with a parallel laser beam having a diameter larger than the diameter of the workpiece as first servo Y-axis laser beam. The second Y-axis direction irradiating means irradiates the processing object in the Y-axis direction with the laser light condensed to a diameter smaller than the diameter of the processing object as the second servo Y-axis direction laser light. The projection of the processing object of the first servo Y-axis direction laser light is incident on the light receiving surface of the first Y-axis direction laser light detector, and the reflected light of the processing object of the second servo Y-axis direction laser light is The light enters the light receiving surface of the second Y-axis direction laser beam detector.

  A common incident optical path of the two Y-axis direction laser light detectors is provided with a relay lens (for example, an imaging lens) that can move in a direction perpendicular to the incident optical path. The Z-axis direction servo means includes first Z-axis direction servo means, second Z-axis direction servo means, and operation switching means. The first Z-axis direction servo means and the second Z-axis direction servo means do not operate at the same time, and are switched by the operation switching means so that the second Z-axis direction servo means operates after the operation of the first Z-axis direction servo means. .

  The first Z-axis direction servo means drives the relay lens so that the projection of the workpiece of the first servo Y-axis direction laser beam is positioned at the center of the light receiving surface of the first Y-axis direction laser beam detector, The objective lens is driven in the Z-axis direction together with the driving of the lens. For example, the first Y-axis direction laser light detection having a light-receiving surface in which a light-receiving area is divided in a direction in which the projection of the servo-target Y-axis direction laser light moves in accordance with the position variation of the processing object in the Z-axis direction. The relay lens is driven so that the difference in the magnitude of the received light signal (light intensity) in the divided light receiving area becomes zero, and the objective lens is driven in the Z-axis direction by an amount corresponding to this drive amount. To do. Therefore, the first Z-axis direction servo means feeds back the projection position of the workpiece of the first servo Y-axis direction laser beam, and the projection is located at the center of the light receiving surface of the first Y-axis direction laser beam detector. Thus, the relay lens can be driven by closed loop control. Then, by driving the objective lens in the Z-axis direction together with the driving of the relay lens, the focal position of the processing laser light is made to coincide with the surface of the processing object.

  Subsequently, the second Z-axis direction servo means moves the relay lens so that the reflected light from the workpiece of the second servo Y-axis direction laser beam is positioned at the center of the light receiving surface of the second Y-axis direction laser beam detector. In addition to driving, the objective lens is driven in the Z-axis direction together with the driving of the relay lens. For example, the second Y-axis direction laser light having a light-receiving surface in which the light-receiving region is divided in the direction in which the reflected light of the processing object of the servo Y-axis direction laser light moves according to the position variation of the processing object in the Z-axis direction. A detector is provided, and the relay lens is driven so that the difference in the magnitude (light intensity) of the light receiving signal in the divided light receiving areas becomes zero, and the objective lens is moved in the Z-axis direction by an amount corresponding to this driving amount. To drive. Therefore, the second Z-axis direction servo means feeds back the position of the reflected light of the workpiece of the second servo Y-axis direction laser light, and the reflected light is centered on the light receiving surface of the second Y-axis direction laser light detector. The relay lens can be driven by closed loop control so as to be positioned. Then, by driving the objective lens in the Z-axis direction together with the driving of the relay lens, the focal position of the processing laser light is made to coincide with the surface of the processing object.

  When detecting the deviation between the focal position of the laser beam and the surface of the workpiece, the detection range is widened by using the projection position of the workpiece, and the detection accuracy is enhanced by using the reflected light position of the workpiece. Therefore, first, focus servo control in the Z-axis direction is started based on the projection position of the processing object (servo control is pulled in), and then focus in the Z-axis direction is based on the reflected light position of the processing object. By performing servo control, the focus servo control in the Z-axis direction can be reliably pulled in, and the focus servo control in the Z-axis direction can be performed with high accuracy.

  Another feature of the laser processing apparatus of the present invention is that the servo laser light irradiation means includes a common laser light source for irradiating the servo Z-axis direction laser light and the servo Y-axis direction laser light, A separation optical path for separating laser light emitted from the laser light source into parallel light having a diameter larger than the diameter of the workpiece and separating the servo Z-axis laser light and the servo Y-axis laser light. The Z-axis direction laser light detection means and the Y-axis direction laser light detection means have a light-receiving surface in which the light-receiving area is divided in a cross shape, and output a light-receiving signal corresponding to the light intensity for each light-receiving area. And combining the servo Z-axis laser beam and the servo Y-axis laser beam so that the projections of the workpieces cross in a cross shape. Photo detector The Y-axis direction servo means is configured such that the optical axis of the laser beam for processing is the object to be processed based on the difference between the received light signals in the left and right or upper and lower light receiving areas of the laser light detector. The objective lens is driven in the Y-axis direction so as to intersect the central axis of the object, and the Z-axis direction servo means is based on the difference between the received light signals in the upper and lower or left and right light receiving regions of the laser light detector, The objective lens is driven in the Z-axis direction so that the focal position of the processing laser beam coincides with the surface of the object to be processed.

  In the present invention, the servo laser light irradiation means includes a common laser light source for irradiating the servo Z-axis direction laser light and the servo Y-axis direction laser light, and is emitted from the laser light source. The laser light is converted into parallel light having a diameter larger than the diameter of the workpiece, and is separated into a servo Z-axis direction laser beam and a servo Y-axis direction laser beam by passing through a separation optical path to the workpiece. And Y-axis direction.

  The servo Z-axis direction laser light and the servo Y-axis direction laser light applied to the object to be processed are combined so that the projections of the object to be processed cross in a cross shape in the combined optical path. The combined laser light is guided to a laser light detector having a light receiving surface in which a light receiving region is divided into a cross shape. In this case, the laser beam detector is used for servo when the optical axis of the machining laser beam intersects the central axis of the workpiece and the focal position of the machining laser beam coincides with the surface of the workpiece. The intersection of the projection of the laser beam in the Z-axis direction and the projection of the laser beam in the Y-axis direction for servo is arranged so as to be the center of the light receiving surface.

  Then, the Y-axis direction servo means has an objective lens so that the optical axis of the processing laser light intersects with the central axis of the object to be processed based on the difference between the light receiving signals in the left and right or upper and lower light receiving areas of the laser light detector. Is driven in the Y-axis direction. In this case, the difference between the received light signals in the light receiving region in the direction in which the projection of the servo Z-axis laser light moves when the workpiece changes in the Y-axis direction may be used. For example, if the projection of the laser beam in the servo Z-axis direction moves up and down on the light-receiving surface when the workpiece changes in the Y-axis direction, the difference between the received light signals in the upper and lower light-receiving areas of the laser light detector Based on this, the objective lens is driven. In the present invention, up and down and left and right do not mean absolute directions, but when one direction on the light receiving surface is defined as up and down, a direction perpendicular to that is defined as left and right. is there.

  As the optical axis of the laser beam for processing is further away from the center axis position of the workpiece, the position of the projection of the workpiece of the laser beam in the Z-axis direction for servo on the light receiving surface of the laser detector deviates from the center. Accordingly, the difference in the magnitude (light intensity) of the received light signal in the left and right or upper and lower light receiving areas also increases. By utilizing this fact, the Y-axis direction servo means uses the objective lens so that the optical axis of the processing laser beam intersects the central axis of the object to be processed based on the difference between the received light signals in the left and right or upper and lower light receiving areas. Can be driven in the Y-axis direction.

  On the other hand, the Z-axis servo means moves the objective lens so that the focal position of the machining laser beam coincides with the surface of the workpiece based on the difference between the received light signals in the upper and lower or left and right light receiving areas of the laser light detector. Drive in the Z-axis direction. In this case, the difference between the received light signals in the light receiving area in the direction in which the projection of the laser light in the Y-axis direction for servo moves when the workpiece changes in the Z-axis direction may be used. For example, if the projection of the laser beam in the Y-axis direction for servo moves left and right when the workpiece is moved in the Z-axis direction, the difference between the received light signals in the left and right light-receiving areas of the laser light detector Based on this, the objective lens is driven.

  As the focal position of the laser beam for processing is farther from the surface of the workpiece, the position of the projection of the workpiece of the laser beam in the Y-axis direction for servo on the light receiving surface of the laser detector deviates from the center. Alternatively, the difference in the magnitude (light intensity) of the received light signal between the left and right light receiving areas also increases. Utilizing this, the Z-axis servo means moves the objective lens so that the focal position of the machining laser beam coincides with the surface of the workpiece based on the difference between the received light signals in the upper and lower or left and right light receiving areas. It can be driven in the Z-axis direction.

  As described above, according to the present invention, the laser light source for focus servo, the laser light detector, and other optical elements can be reduced, so that the cost can be reduced.

  Another feature of the laser processing apparatus of the present invention is that the intensity of the reflected light of the processing laser light irradiated on the surface of the object to be processed is detected by the processing laser light irradiation means, and the intensity of the detected reflected light is detected. In other words, a focus position improper determination means for determining that the focus position of the laser beam for processing is not appropriate when the value is equal to or less than a reference value is provided.

  In the present invention, the focal position improperness determining means detects the intensity of the reflected light of the processing laser light irradiated on the surface of the processing object, and when the detected intensity of the reflected light is equal to or less than a reference value, It is determined that the focal position of the processing laser beam is not appropriate. Therefore, before starting laser processing, check whether focus servo control is properly performed by the focus position improper determination means with the Y-axis direction servo means and Z-axis direction servo means activated. can do. For this reason, it becomes possible to prevent the failure of laser processing.

  Furthermore, the embodiment of the present invention is not limited to the invention of the laser processing apparatus, and can also be implemented as an invention of a focus servo control method of the laser processing apparatus.

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 a schematic block diagram of the servo Y-axis direction optical head and Y-axis direction light receiving device 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. It is a characteristic view showing the relationship between the displacement of a workpiece and an error signal waveform value. It is explanatory drawing showing the state of the projection irradiated to the photodetector. It is a flowchart showing a laser processing control routine. It is a schematic block diagram of the process head of the laser processing apparatus which concerns on 2nd Embodiment. It is explanatory drawing showing the relationship between the displacement of a process target object, and the position change of the reflected light irradiated to the photodetector. It is a schematic block diagram of the Y-axis direction light-receiving device and Z-axis direction servo system circuit of the laser processing apparatus which concerns on 3rd Embodiment. It is a schematic block diagram of the Y-axis direction light-receiving device and Z-axis direction servo system circuit of the laser processing apparatus which concerns on 4th Embodiment. It is a flowchart (change part) showing the laser processing control routine of the laser processing apparatus which concerns on 4th Embodiment. It is a schematic block diagram of the process head and servo system circuit of the laser processing apparatus which concerns on 5th Embodiment. It is explanatory drawing showing the state of the cross-shaped projection irradiated to the photodetector. It is a schematic block diagram of the process head of the laser processing apparatus which concerns on the modification of 5th 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. This laser processing apparatus performs laser processing by irradiating the surface of a thin cylindrical pipe-shaped object OB with a processing laser beam in a spiral shape. 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), Similarly, the servo Y-axis direction optical head 30 that irradiates the surface of the workpiece OB with the servo Y-axis direction laser light (see FIG. 3), and the servo Y-axis direction optical head 30 that is irradiated from the servo Y-axis direction optical head 30. A Y-axis direction light receiving device 40 that receives laser light (see FIG. 3), various electric circuits (described later), and a controller 90 that controls the operation of the entire laser processing device are provided.

  Here, the direction in the laser processing apparatus is defined. As shown in FIG. 4, 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 perpendicular 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 perpendicular to both the X-axis direction and the Z-axis direction is referred to as a Y-axis direction. The servo Y-axis direction optical head 30 is fixed so that the optical axis of the servo laser light applied to the workpiece OB is in the Y-axis direction. Accordingly, the servo Y-axis direction optical head 30 and the Y-axis direction light receiving device 40 are located before and after the paper surface in FIG. 1, but here, they are described by being arranged on the left and right sides so that they do not overlap. is doing.

  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 processing laser beam deviates from the center axis of the processing object OB, an appropriate focus error signal cannot be obtained. Therefore, in the present embodiment, the processing object OB is irradiated with servo laser light in the Z-axis direction and the Y-axis direction, and the focal position of the processing laser light is based on the position of the projection on which the processing object OB is projected. To control.

  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. It has a function of outputting a signal corresponding to the displacement 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. Yes. Accordingly, by operating the Z-axis actuator 114z, the focal position of the processing laser light 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 light can be changed to the Y-axis. It can be moved in the 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 beam condensed by the objective lens 112 is irradiated and reflected on the surface of the processing object OB. The reflected light reflected by the object OB passes through the objective lens 112, the dichroic mirror 110, and the quarter wavelength plate. In this case, since the reflected light has passed through the quarter-wave plate 108 twice, the direction of polarization is 90 ° different 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 polarization 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 in response to a command from the controller 90, converts 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 light 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 on the photoresist). This is a circuit for supplying a current and a voltage for emitting a laser beam having an intensity capable of forming a laser beam. 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 to detect 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 light and the processing laser light are the rotation axis of the work driving device 50 (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. Therefore, 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 light reflected by the dichroic mirror 110 is converted into 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. 5, 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.

  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.

  FIG. 6 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. Therefore, in the range r (referred to as the S-shaped detection range r) from the peak (c position) to the valley (a position) of the S-shaped waveform, the amount of deviation 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 servo laser light 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.

  Next, the servo Y-axis direction optical head 30 and the Y-axis direction light receiving device 40 will be described. As shown in FIG. 3, the servo Y-axis direction optical head 30 and the Y-axis direction light receiving device 40 have a main body frame (not shown) of the laser processing apparatus so as to face each other with the workpiece OB sandwiched in the Y-axis direction. Fixed to. The servo Y-axis optical head 30 includes a laser light source 302 that emits servo laser light, a collimator lens 304 and a polarization beam splitter 306 that are provided along the optical axis of the servo laser light emitted from the laser light source 302. And a condenser lens 308 and a photodetector 310 provided in the reflection direction of the polarization beam splitter 306.

  The laser light source 302 is driven by the current and voltage supplied from the servo Y-axis direction laser drive circuit 340 and emits servo laser light. The servo laser light emitted from the laser light source 302 is collimated by the collimator lens 304 and enters the polarization beam splitter 306. Most of the servo laser light (for example, 95%) passes through the polarization beam splitter 306 as it is and exits from the servo Y-axis optical head 30. The laser beam emitted from the servo Y-axis direction optical head 30 is the servo Y-axis direction laser beam. The servo Y-axis direction laser light becomes parallel light having a diameter larger than the diameter of the workpiece OB.

  The servo Y-axis direction optical head 30 is positioned so that the emission direction of the servo Y-axis direction laser beam is the Y-axis direction, and the optical axis intersects with the rotation axis of the workpiece driving device 50. The Y-axis direction light receiving device 40 facing the servo Y-axis direction optical head 30 is provided with a photodetector 402 that receives the servo Y-axis direction laser light. The photodetector 402 is positioned so that the optical axis of the servo Y-axis direction laser beam passes through the center of the light receiving surface. Since the servo Y-axis direction laser beam emitted from the servo Y-axis direction optical head 30 is parallel light having a diameter larger than the diameter of the workpiece OB, the shadow of the workpiece OB is reflected on the light receiving surface of the photodetector 402. A rod-like projection is projected.

  As shown in FIG. 7, the photodetector 402 includes a light receiving element whose light receiving area is divided into two vertically (in the Z-axis direction), and receives a detection signal proportional to the intensity of light incident on the light receiving areas C and D. Output as signals (c, d). This photodetector 402 is processed so that the rod-shaped projection S in the received servo Y-axis laser light (projection light L) for the servo is parallel to the dividing line DIV of the light receiving regions C and D and viewed from the Y-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.

  The light reception signal (c, d) output from the photodetector 402 is input to the Z-axis direction error signal generation circuit 171. The Z-axis direction error signal generation circuit 171 amplifies the received light signal (c, d), calculates a difference in light intensity (cd) using this signal, and calculates the calculation result as a Z-axis direction error signal ( cd) is output to the Z-axis servo circuit 172. The magnitude of the Z-axis direction error signal (cd) is S-shaped, similar to the characteristics of the Y-axis direction error signal (ab) described above, when the position of the workpiece OB is changed in the Z-axis direction. (See FIG. 6). Accordingly, in the S-shaped detection range r, the amount of deviation in the Z-axis direction of the workpiece OB (the amount of deviation in the Z-axis direction between the center axis of the workpiece OB and the rotation axis of the workpiece driving device 50) and the Z-axis direction. There is a one-to-one correspondence with the magnitude of the error signal (cd). 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 Z-axis direction based on the Z-axis direction error signal (cd).

  The Z-axis direction servo circuit 172 starts to operate in response to a command from the controller 90, and based on the Z-axis direction error signal (cd) input from the Z-axis direction error signal generation circuit 171, Z of the workpiece OB is set. A shift amount in the axial direction is detected, and a Z-axis servo signal indicating the Z-axis direction movement amount of the objective lens 112 corresponding to the shift amount is generated and output to the Z-axis drive circuit 173. The Z-axis direction drive circuit 173 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. Therefore, the objective lens 112 is maintained at a position away from the origin position in the Z-axis direction by the amount of deviation of the workpiece OB in the Z-axis direction. Note that the position of the projection displayed on the photodetector 402 does not change with the movement of the objective lens 112 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 servo Y-axis direction optical head 30 reflects a part (for example, 5%) of the servo laser light emitted from the laser light source 302 by the polarization beam splitter 306, and the reflected light by the condenser lens 308. The structure which condenses on the light-receiving surface is provided. The photodetector 310 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 310 outputs a light reception signal corresponding to the intensity of the servo laser light emitted from the laser light source 302. This light reception signal is supplied to the servo Y-axis direction laser drive circuit 340.

  The servo Y-axis direction laser drive circuit 340 does not change the surface of the workpiece OB with respect to the laser light source 302 based on a command from the controller 90, and the photo-detector 402 of the Y-axis direction light receiving device 40 is used. This is a circuit for supplying current and voltage for emitting servo laser light having an intensity capable of detecting projected light. In the present embodiment, the servo Y-axis direction laser drive circuit 340 feeds back the light reception signal output from the photodetector 310 and outputs the current output to the laser light source 302 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 Y-axis direction laser light emitted from the servo Y-axis direction optical head 30 is maintained at a constant appropriate value.

  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. 8 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 and the servo Y-axis direction laser drive circuit 340. Accordingly, the servo Z-axis direction laser head 20 irradiates the servo Z-axis direction laser beam to the workpiece OB in the Z-axis direction, and the servo Y-axis direction optical head 30 emits the servo Y-axis direction laser beam. Irradiation is performed on the workpiece OB in the Y-axis direction. This process corresponds to a servo laser beam irradiation step including the Z-axis direction irradiation step and the Y-axis direction irradiation step of the present invention. Further, the process in which the photodetector 118 outputs the light reception signal (a, b) by the irradiation of the servo laser light corresponds to the Z-axis direction laser light detection step of the present invention, and the photodetector 402 receives the light reception signal (c, d). ) Corresponds to the Y-axis direction laser beam detection step of the present invention.

  Subsequently, in step S110, the controller 90 outputs a servo control start command to the Y-axis direction servo circuit 162 and the Z-axis direction servo circuit 172. 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. This process corresponds to the Y-axis direction servo step of the present invention.

  Similarly, the Z-axis direction servo circuit 172 receives the Z-axis direction error signal (cd) from the Z-axis direction error signal generation circuit 171 and performs machining based on the Z-axis direction error signal (cd). The amount of deviation of the object OB in the Z-axis direction is detected, and a Z-axis direction servo signal representing the amount of movement of the objective lens 112 in the Z-axis direction corresponding to the amount of deviation is generated and output to the Z-axis direction drive circuit 173. The Z-axis direction drive circuit 173 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. Accordingly, the objective lens 112 is controlled to a position away from the origin position in the Z-axis direction by the amount of deviation of the processing object OB in the Z-axis direction, and the focal position of the processing laser light always matches the surface of the processing object OB. To come. This processing corresponds to the Z-axis direction servo step of the present invention.

  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. Accordingly, a non-machining intensity laser beam 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 exceeds the lower limit value Rref. If the reflected light intensity R exceeds 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 less than or equal to 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. The processing in steps S116 and S138 corresponds to the focal position inappropriateness determination step of the present invention.

  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 to 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, the processing head 10 emits a laser beam having a processing intensity 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. Accordingly, 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 whether or not the current movement position has reached the machining end position in step S124. . The processes in steps S122 and S124 are repeated until the moving position of the moving stage 51 reaches the processing end position. Accordingly, 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 (S124: Yes), the controller 90 outputs a processing laser light irradiation stop command to the processing laser drive circuit 150 in step S126. 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, in step S130, the controller 90 outputs a servo control stop command to the Y-axis direction servo circuit 162 and the Z-axis direction servo circuit 172. As a result, the operations of the Y-axis actuator 114z and the Z-axis actuator 114z are stopped. Next, in step S132, a servo laser light irradiation stop command is output to the servo Z-axis direction laser drive circuit 240 and the servo Y-axis direction laser drive circuit 340. Thereby, the irradiation of the servo Z-axis direction laser light from the servo Z-axis direction optical head 20 and the irradiation of the servo Y-axis direction laser light from the servo Y-axis direction optical head 30 are 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 processing object OB is irradiated with the servo Z-axis direction laser light and the servo Y-axis direction laser light onto the processing object OB, and the projection thereof. Of the objective lens 112 so that the position of the optical axis of the processing laser beam intersects the central axis of the processing object OB and the focal position coincides with the surface of the processing object OB. The direction and the position in the Y-axis direction are controlled. Therefore, even when the surface of a very thin pipe-shaped workpiece OB of 50 μm is laser-processed as in the present embodiment, the laser beam for processing that is properly condensed is irradiated perpendicularly to the surface of the workpiece OB. 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 present 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 (ab) obtained from the light reception signal of the photodetector 118. Thus, the Y-axis actuator 114y is driven by closed loop control so that the Y-axis direction error signal (ab) is always zero, so that the Y-axis direction servo control can be performed with high accuracy.

  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.

  In order to control the outputs of the laser light sources 202 and 302 so that the intensity of the light detected by the photodetectors 210 and 310 becomes the set intensity when the servo Z-axis laser light and the servo Y-axis laser light are emitted. Servo control in the Z-axis direction and the Y-axis direction can be performed with high accuracy.

  Next, a laser processing apparatus according to the 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 a processing laser beam 102, a collimating lens 104, a polarization beam splitter 106, and a 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, 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.

  Similarly to the processing laser light, the servo laser light is condensed to a diameter smaller than the diameter of the processing object OB by the objective lens 112 and 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 return 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) passes 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 °. 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.

  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 received light signal (a, b), calculates a light intensity difference (ab) using this signal, and outputs the calculated result as a Y-axis direction error signal (a -B) is output to the Y-axis direction servo circuit 162. 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) 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 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 163 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 the reflected light is received by 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, and the servo Y-axis optical head 30 is larger than the diameter of the workpiece OB. A servo laser beam having a diameter (parallel light) is irradiated onto the workpiece OB, and the projected light is received by the Y-axis direction light receiving device 40, and the focal position of the machining laser beam is processed based on the position of the projection. The position of the objective lens 112 in the Z-axis direction is controlled so as to coincide with the surface position of the object OB. Accordingly, 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.

  Next, a laser processing apparatus according to the third embodiment will be described. The laser processing apparatus according to the third embodiment can perform servo control in the Z-axis direction by closed-loop control. The laser processing apparatus according to the first embodiment includes a Y-axis direction light receiving device and a Z-axis direction. The other servo system circuits are the same as those in the first embodiment.

  As shown in FIG. 11, the Y-axis direction light receiving device 43 in the laser processing apparatus according to the third embodiment has a first relay lens 404 and a second relay at the incident portion of the photodetector 402 of the Y-axis direction light receiving device 40 in the first embodiment. A relay lens 406 is provided, and a relay lens actuator 408 that drives the first relay lens 404 in the Z-axis direction is further provided. The first relay lens 404 condenses the servo Y-axis direction laser light (projected light of the workpiece OB) emitted from the servo Y-axis direction optical head 30, and the second relay lens 406 is the first relay lens. The servo laser beam condensed in 404 is returned to parallel light. The photodetector 402 receives the servo Y-axis direction laser light that has passed through the second relay lens 406. The position of the first relay lens 404 can be moved in the Z-axis direction by a relay lens actuator 408. The first relay lens 404 is positioned at the center of the movable range in the Z-axis direction when the relay lens actuator 408 is not energized (this position is referred to as the origin position). The photodetector 402 is positioned so that the optical axis of the servo Y-axis direction laser beam passes through the center of the light receiving surface when the first relay lens 404 is at the origin position.

  A rod-like projection of the workpiece OB is projected on the light receiving surface of the photodetector 402, but when the first relay lens 404 is driven in the Z-axis direction by the relay lens actuator 408, the projection is accompanied by the movement. The position also moves in the Z-axis direction.

  As described above, the photodetector 402 includes a light receiving element in which the light receiving region is divided into two in the vertical direction (Z-axis direction), and a detection signal proportional to the intensity of light incident on the light receiving regions C and D is received as a light receiving signal (c , D). In addition, the photodetector 402 is arranged so that the rod-like projection of the received servo Y-axis laser light is parallel to the dividing line DIV of the light-receiving area, and the first relay lens 404 is at the origin position and viewed from the Y-axis direction. When the center axis of the workpiece OB coincides with the rotation axis of the workpiece driving device 50, the projection of the workpiece OB is arranged at a position that is equally divided by the dividing line DIV of the light receiving area.

  The laser processing apparatus of the third embodiment includes a Z-axis direction servo circuit 182 and a Z-axis direction drive circuit 183 instead of the Z-axis direction servo circuit 172 and the Z-axis direction drive circuit 173 of the first embodiment. The Z-axis direction error signal generation circuit 171 is the same as that in the first embodiment. The light reception signal (c, d) output from the photodetector 402 is input to the Z-axis direction error signal generation circuit 171. The Z-axis direction error signal generation circuit 171 amplifies the received light signal (c, d), calculates a difference in light intensity (cd) using this signal, and calculates the calculation result as a Z-axis direction error signal ( cd) is output to the Z-axis servo circuit 182. The Z-axis direction servo circuit 182 receives the Z-axis direction error signal (cd), generates a Z-axis direction servo signal such that the Z-axis direction error signal (cd) is always zero, and generates a Z-axis direction servo signal. Output to the direction drive circuit 183. The Z-axis direction drive circuit 183 outputs a signal for driving the relay lens actuator 408 based on the Z-axis direction servo signal to move the first relay lens 404 in the Z-axis direction, and at the same time, the Z-axis actuator of the machining head 10 A signal for driving 114z is output to move the objective lens 112 in the Z-axis direction. In this case, each drive signal is set so that the movement amount of the first relay lens 404 and the movement amount of the objective lens 112 are the same. Accordingly, the relative position of the objective lens 112 and the first relay lens 404 in the Z-axis direction hardly changes.

  In the first embodiment, since only the objective lens 112 is moved in the Z-axis direction, the projection of the processing object OB projected on the photodetector 402 does not move, but in the third embodiment, the first relay lens. Since 404 also moves in the Z-axis direction by the Z-axis direction servo signal, the projection of the processing object OB projected on the photodetector 402 moves in the Z-axis direction. Therefore, in the Z-axis direction servo control in the third embodiment, the projection of the workpiece OB projected on the photodetector 402 is always at the center of the light receiving surface, that is, the position where the projection is divided into two equal parts by the dividing line DIV of the light receiving area. Thus, the first relay lens 404 is driven in the Z-axis direction, and the objective lens 112 is driven in the Z-axis direction accordingly. Therefore, since the closed loop control is performed not only in the Y-axis direction servo control but also in the Z-axis direction servo control, the Z-axis direction servo control is also highly accurate. Further, even if the workpiece OB greatly fluctuates in the Z-axis direction, the relay lens actuator 408 adjusts the first relay lens 404 so that the position of the projection projected on the photodetector 402 is on the center side of the light receiving surface. Since it is moved, the detection area in the Z-axis direction of the workpiece OB is widened.

  Moreover, the laser processing apparatus of 3rd Embodiment performs the laser processing control routine similar to 1st Embodiment. In this case, in step S110, the Y-axis actuator 114y is driven based on the Y-axis direction servo signal such that the Y-axis direction error signal (ab) is always zero, and the Z-axis direction error signal (c− The relay lens actuator 408 is driven based on the Z-axis direction servo signal so that d) is always zero, and the Z-axis actuator 114z is driven with a drive amount equal to that.

  According to the laser processing apparatus of the third embodiment described above, in addition to the effects of the first embodiment, the detection range of the workpiece OB in the Z-axis direction is widened. Can be widened. Further, since the closed loop control is performed, the Z-axis direction servo control can be performed with high accuracy.

  Next, a laser processing apparatus according to the fourth embodiment will be described. In the third embodiment, one servo Y-axis direction laser beam is irradiated onto the workpiece OB, and the Z-axis servo control is performed based on the projection position of the workpiece OB. In the fourth embodiment, another servo Y-axis direction laser beam is irradiated onto the workpiece OB and the position of the reflected light is detected, so that the Z-axis is based on the positions of both the projection and the reflected light. Direction servo control is performed. As shown in FIG. 12, the laser processing apparatus of the fourth embodiment includes a second servo Y-axis direction optical head 44 instead of the Y-axis direction light receiving device 43 in the laser processing apparatus of the third embodiment. .

  The laser processing apparatus of the fourth embodiment is the same as the laser processing apparatus of the third embodiment except for the configuration described below, but the servo Y-axis direction optical head 30 and the second servo Y-axis direction are the same. In order to distinguish from the optical head 44, the servo Y-axis direction optical head 30 is referred to as a first servo Y-axis direction optical head 30. Also, the servo laser light emitted from the first servo Y-axis direction optical head 30 is called a first servo Y-axis direction laser light, the laser light source 302 is called a first laser light source 302, and the first laser light source 302 is called. The servo Y-axis direction laser drive circuit 340 for driving is called a first servo Y-axis direction laser drive circuit 340.

  First, the configuration for detecting the projection of the workpiece OB of the first servo Y-axis direction laser light in the second servo Y-axis direction optical head 44 will be described. As shown in FIG. 12, the second servo Y-axis direction optical head 44 includes a first relay lens 404, a second relay lens 406, a photodetector 402, and a relay, similarly to the Y-axis direction light receiving device 43 of the third embodiment. A lens actuator 408 is provided, and a dichroic mirror 418 is further interposed between the first relay lens 404 and the second relay lens 406. The wavelength of the first servo Y-axis direction laser light is set so that the wavelength is reflected by the dichroic mirror 418. Accordingly, the optical path traveled by the first servo Y-axis direction laser beam is bent 90 degrees by the dichroic mirror 418.

  The first servo Y-axis direction laser light incident on the first relay lens 404 becomes projection light of the workpiece OB. The projected light passes through the first relay lens 404 and is collected and reflected by the dichroic mirror 418. Then, the light is returned to parallel light by the second relay lens 406 and is incident on the light receiving surface of the photodetector 402. As a result, a rod-like projection of the workpiece OB is projected on the light receiving surface of the photodetector 402. Hereinafter, the photo detector 402 is referred to as a first photo detector 402.

  The first photodetector 402 includes a light receiving element in which a light receiving region is divided into right and left (in the Y-axis direction), and a detection signal proportional to the intensity of light incident on the light receiving regions C and D is received as a light receiving signal (c, d). ). The first photodetector 402 has a Y-axis laser beam at the origin position so that the rod-like projection of the received first servo Y-axis laser beam is parallel to the dividing line DIV of the light-receiving area. When the center axis of the workpiece OB coincides with the rotation axis of the workpiece driving device 50 as viewed from the direction, the projection of the workpiece OB is arranged at a position that is divided into two equal parts by the dividing line DIV of the light receiving area. .

  The position of the first relay lens 404 can be moved in the Z-axis direction by a relay lens actuator 408. The first relay lens 404 is located at the center of the movable range in the Z-axis direction, that is, at the origin when the relay lens actuator 408 is not energized.

  The second servo Y-axis direction optical head 44 further irradiates the workpiece OB with the second servo Y-axis direction laser light from the opposite direction to the first servo Y-axis direction laser light, and reflects the reflected light. As a configuration for detecting light, a second laser light source 410, a collimating lens 412, a polarization beam splitter 414, a ¼ wavelength plate 416, and a second photodetector 420 are provided. The second laser light source 410 is driven by the current and voltage supplied from the second servo Y-axis direction laser drive circuit 440 to emit servo laser light. The servo laser light emitted from the second laser light source 410 is collimated by the collimator lens 412 and enters the polarization beam splitter 414. Most of the servo laser light (for example, 95%) passes through the polarization beam splitter 414 as it is, passes through the quarter wavelength plate 416, and is converted from linearly polarized light to circularly polarized light. The servo laser light that has passed through the quarter-wave plate 416 passes through the dichroic mirror 418 and enters the first relay lens 404. The first relay lens 404 condenses servo laser light because it functions as an objective lens. In this way, the laser spot focused to a diameter smaller than the diameter of the workpiece OB is irradiated on the surface of the workpiece OB.

  The servo laser beam (second servo Y-axis laser beam) irradiated on the workpiece OB is reflected by the surface of the workpiece OB, enters the first relay lens 404, and is returned to parallel light. The light passes through the dichroic mirror 418 as it is, and further passes through the quarter wavelength plate 416. In this case, the second servo Y-axis direction laser beam is reflected by the polarization beam splitter 414 because the polarization direction is 90 ° different from that of the servo laser beam emitted from the second laser light source 410. A second photodetector 420 is provided in the reflection direction of the polarization beam splitter 414. Accordingly, the second servo Y-axis direction laser light reflected by the surface of the workpiece OB is incident on the second photodetector 420. The second photodetector 420 includes a light receiving element in which the light receiving region is divided into right and left (in the Y-axis direction), and a detection signal proportional to the intensity of light incident on the light receiving regions E and F is received as a light receiving signal (e, Output as f). This second photodetector 420 is to be processed when the first relay lens 404 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 when viewed from the Y-axis direction. The reflected light reflected by the object OB is arranged at a position that is divided into two equal parts by the dividing line DIV of the light receiving region.

  The second servo Y-axis direction optical head 44 reflects a part (for example, 5%) of the servo laser light emitted from the second laser light source 410 by the polarization beam splitter 414 and collects the reflected light. The optical lens 422 is configured to collect light on the light receiving surface of the photodetector 424. The photodetector 424 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 424 outputs a light reception signal corresponding to the intensity of the servo laser light emitted from the second laser light source 410. This light reception signal is supplied to the second servo Y-axis direction laser drive circuit 440.

  The second servo Y-axis direction laser drive circuit 440 does not change the surface of the object to be processed OB with respect to the second laser light source 410 based on a command from the controller 90, and is processed by the second photodetector 420. This is a circuit for supplying a current and a voltage for emitting servo laser light having an intensity capable of detecting reflected light from the object OB. The second servo Y-axis direction laser drive circuit 440 feeds back the light reception signal output from the photodetector 424 and outputs the current or voltage output to the second laser light source 410 so that the intensity of the light reception signal becomes a preset set intensity. Adjust. As a result, the intensity of the servo Y-axis direction laser light emitted from the second servo Y-axis direction optical head 44 is maintained constant.

  The laser processing apparatus of the fourth embodiment includes a Z-axis direction error signal generation circuit 191 and a Z-axis direction servo circuit 192 in place of the Z-axis direction error signal generation circuit 171 and the Z-axis direction servo circuit 182 of the third embodiment. I have. The Z-axis direction drive circuit 183 is the same as that in the third embodiment.

  The light reception signal (c, d) output from the first photodetector 402 and the light reception signal (e, f) output from the second photodetector 420 are input to the Z-axis direction error signal generation circuit 191. The Z-axis direction error signal generation circuit 191 includes a first generation unit 1911 and a second generation unit 1912, and a light reception signal (c, d) output from the first photodetector 402 is input to the first generation unit 1911. The light reception signal (e, f) output from the second photodetector 420 is input to the second generator 1912. The first generation unit 1911 amplifies the light reception signal (c, d), calculates a difference in light intensity (cd) using this signal, and outputs the calculation result as the first Z-axis direction error signal (c−). Output as d). The second generator 1912 amplifies the received light signal (e, f), calculates the difference in light intensity (ef) using this signal, and outputs the calculated result as the second Z-axis direction error signal (e−). Output as f).

  The first Z-axis direction error signal (cd) and the second Z-axis direction error signal (ef) are input to the Z-axis direction servo circuit 192. The Z-axis direction servo circuit 192 includes a first servo unit 1921 and a second servo unit 1922, and the first Z-axis direction error signal (cd) is input to the first servo unit 1921 and the second Z-axis direction error signal is input. (Ef) is input to the second servo unit 1922.

  The first servo unit 1921 starts to operate in response to a servo start command output from the controller 90, and the first Z-axis direction error signal (cd) is always based on the first Z-axis direction error signal (cd). A Z-axis direction servo signal that becomes zero is generated and output to the Z-axis direction drive circuit 183. Therefore, the first relay lens 404 is positioned in the Z-axis direction so that the projection of the workpiece OB projected on the first photodetector 402 is at the center of the light receiving surface, that is, at a position that is equally divided by the dividing line DIV of the light receiving area. The objective lens 112 is driven in the Z-axis direction with the same driving amount. Further, the first servo unit 1921 stops its operation based on a servo switching command from the controller 90.

  The second servo unit 1922 starts operation in place of the first servo unit 1921 in response to a servo switching command output from the controller 90, and based on the second Z-axis direction error signal (ef), the second Z-axis direction A Z-axis direction servo signal is generated so that the error signal (ef) is always zero, and is output to the Z-axis direction drive circuit 183. Accordingly, the first relay lens 404 is driven in the Z-axis direction so that the reflected light of the second servo Y-axis laser light received by the second photodetector 420 is maintained in the center of the light receiving region, and the same drive as this is performed. The objective lens 112 is driven in the Z-axis direction by the amount.

  Next, a laser processing control routine executed by the controller 90 in the fourth embodiment will be described. The laser processing control routine of the fourth embodiment is different from that of the first embodiment in steps S108 to S110 and steps S130 to S132. FIG. 13 is a partial flowchart showing the process of the fourth embodiment performed in place of the processes of steps S108 to S110 and steps S130 to S132 in the first embodiment.

  In step S106, the controller 90 outputs a rotation start command to the spindle motor control circuit 56. Subsequently, in step S201, the servo Z-axis direction laser drive circuit 240 and the first servo Y-axis direction laser drive circuit are provided. The servo laser beam irradiation start command is output to 340. Accordingly, the servo Z-axis direction laser head 20 irradiates the servo Z-axis direction laser beam to the workpiece OB in the Z-axis direction, and the first servo Y-axis direction optical head 30 emits the first servo Y-axis. Directional laser light is applied to the workpiece OB in the Y-axis direction. The process of irradiating the first servo Y-axis direction laser beam from the first servo Y-axis direction optical head 30 corresponds to the first Y-axis direction irradiation step of the present invention. Further, the process in which the first photodetector 402 outputs the light reception signal (c, d) by the irradiation of the first servo Y-axis laser beam corresponds to the first Y-axis direction laser beam detection step of the present invention.

  Subsequently, the controller 90 outputs a servo start command to the Z-axis direction servo circuit 192 and the Y-axis direction servo circuit 162 in step S202. Thereby, each servo circuit starts the above-described Z-axis direction servo and Y-axis direction servo control. In this case, in the Z-axis direction servo circuit 192, only the first servo unit 1921 operates to generate a Z-axis direction servo signal. The processing of the first generation unit 1911, the first servo unit 1921, and the Z-axis direction drive circuit 183 in this case corresponds to the first Z-axis direction servo step of the present invention.

  Subsequently, in step S203, the controller 90 stands by until a predetermined time has elapsed from the output of the servo start command. During this time, the servo control described above is continued. In this case, in the Z-axis direction servo, the projection of the workpiece OB of the first servo Y-axis direction laser light emitted from the first servo Y-axis direction optical head 30 is the second servo Y-axis direction light. The first relay lens 404 is driven in the Z-axis direction so as to be positioned at the center of the light-receiving surface of the first photodetector 402 of the head 44, and the objective lens 112 is driven in the Z-axis direction with the same driving amount. Wide range of servo control in the axial direction. Therefore, even if the center axis of the workpiece OB is greatly displaced in the Z-axis direction with respect to the rotation center axis of the workpiece driving device 50, the focal position of the machining laser beam is moved to the surface of the workpiece OB. Can do.

  When a predetermined time has elapsed from the output of the servo start command (S203: Yes), the controller 90, in step S204, the first servo Y-axis direction laser drive circuit 340, the second servo Y-axis direction laser drive circuit 440, and the Z-axis A servo switching command is output to the direction servo circuit 192. As a result, the driving of the first laser light source 302 by the first servo Y-axis direction laser drive circuit 340 is stopped, and the driving of the second laser light source 410 by the second servo Y-axis direction laser drive circuit 440 is started instead. Is done. Accordingly, the workpiece OB is irradiated with the second servo Y-axis direction laser beam instead of the first servo Y-axis direction laser beam. The process of irradiating the second servo Y-axis direction laser beam from the second servo Y-axis direction optical head 44 corresponds to the second Y-axis direction irradiation step of the present invention. Further, the process in which the second photodetector 420 outputs the light reception signal (e, f) by the irradiation of the second servo Y-axis laser beam corresponds to the second Y-axis direction laser beam detection step of the present invention.

  At the same time, in the Z-axis direction servo circuit 192, the second servo unit 1922 starts operating instead of the first servo unit 1921. As a result, the servo control mode in the Z-axis direction is switched, and the first relay lens so that the reflected light from the workpiece OB of the second servo Y-axis direction laser light comes to the center position of the light receiving surface of the second photodetector 420. 404 is driven in the Z-axis direction, and the objective lens 112 is driven in the Z-axis direction with the same drive amount. In this case, since Z-axis direction servo control is performed based on the reflected light position, the second Z-axis direction error signal (ef) output from the second servo unit 1922 with respect to the displacement of the workpiece OB in the Z-axis direction. Thus, the Z-axis servo control can be performed with high accuracy. The processes of the second generation unit 1912, the first servo unit 1922, and the Z-axis direction drive circuit 183 in this case correspond to the second Z-axis direction servo step of the present invention. When the controller 90 switches the servo control mode in the Z-axis direction in step S204, the controller 90 executes the processing from step S112 described above.

  The controller 90 executes the processes of steps S205 and S206 instead of the processes of steps S130 and S132 of the first embodiment. In step S <b> 205, the controller 90 outputs a servo control stop command to the Z-axis direction servo circuit 192 and the Y-axis direction servo circuit 162. As a result, the operations of the Z-axis actuator 114z, the Y-axis actuator 114y, and the relay lens actuator 408 are stopped. Subsequently, in step S206, a servo laser light irradiation stop command is output to the servo Z-axis direction laser drive circuit 240 and the second servo Z-axis direction laser drive circuit 440. As a result, the irradiation of the servo Z-axis direction laser light from the servo Z-axis direction optical head 20 and the irradiation of the second servo Y-axis direction laser light from the second servo Y-axis direction optical head 44 are stopped. Is done.

  According to the laser processing apparatus of the fourth embodiment described above, first, focus servo control in the Z-axis direction is started based on the detection position of projection of the workpiece OB (servo control is pulled in), and then Since the Z-axis servo control is performed based on the detection position of the reflected light of the workpiece OB, the Z-axis servo control can be reliably pulled in and the Z-axis servo control can be performed with high accuracy. it can.

  Next, a laser processing apparatus according to the fifth embodiment will be described. In the laser processing apparatuses of the first to fourth embodiments described above, separate laser light sources are provided in the Z-axis direction and the Y-axis direction as the servo laser light irradiation sources, and these servo laser lights are detected. In the fifth embodiment, a configuration in which the laser light source and the photodetector are used in common in the Z-axis direction and the Y-axis direction is employed.

  FIG. 14 shows a schematic configuration of the machining head 15 in the laser machining apparatus of the fifth embodiment. This processing head 15 is provided in place of the processing head 10, servo Z-axis direction optical head 20, servo Y-axis direction optical head 30, and Y-axis direction light receiving device 40 in the first embodiment. A function of irradiating the surface of the object OB with the processing laser light, a function of irradiating the processing object OB with the servo Z-axis direction laser light and the servo Y-axis direction laser light, and the processing object OB. Further, it has a function of detecting projection light of both the servo Z-axis direction laser beam and the servo Y-axis direction laser beam. In the figure, the same components as those in the first embodiment are denoted by the same reference numerals as those used in the first embodiment, and are simply described.

  The processing head 15 is provided with a region H (space) through which the processing object OB is inserted at the center, and is configured to emit processing laser light and servo laser light to the region H. . The processing head 15 is configured to irradiate the processing laser beam onto the surface of the processing object OB, and the laser light source 102 driven by the processing laser driving circuit 150 and the processing laser light emitted from the laser light source 102 are processed. A collimating lens 104, a polarizing beam splitter 106, a quarter-wave plate 108, a dichroic mirror 110, an objective lens 112, and a focus for adjusting the positions of the objective lens 112 in the Z-axis direction and the Y-axis direction provided along the optical axis. Actuator 114 (Z-axis actuator 114z, Y-axis actuator 114y). Moreover, the condensing lens 120 and the photodetector 122 are provided as a structure for detecting the intensity | strength of the reflected light which the processing laser beam reflected in the process target OB. Further, a condensing lens 124 and a photodetector 126 are provided as a configuration for detecting the intensity of the processing laser beam. These configurations are the same as those in the first embodiment. Accordingly, the path along which the processing laser light travels and the control based on the outputs of the photodetectors 122 and 126 are the same as in the first embodiment.

  In the processing head 15, 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 work driving device 50, the focal position of the processing laser beam is the processing target. Positioned to coincide with the surface of the object OB.

  Next, a configuration for irradiating the workpiece OB with servo laser light will be described. The processing head 15 is similar to the servo Z-axis optical head 20 of the first embodiment. The laser light source 202 emits servo laser light, and the servo laser light emitted from the laser light source 202 is converted into parallel light. A collimating lens 204, a polarizing beam splitter 206 that transmits most of parallel light (for example, 95%) and reflects the rest, a condensing lens 208 provided in the reflecting direction of the polarizing beam splitter 206, and a condensing lens 208. A photodetector 210 for detecting the intensity of the emitted servo laser light is provided. The laser light source 202 is driven by the current and voltage supplied from the servo laser drive circuit 540 and emits servo laser light. The servo laser drive circuit 540 corresponds to the servo Z-axis direction laser drive circuit 240 of the first embodiment, and the laser light source is set so that the light intensity of the servo laser light detected by the photodetector 210 becomes the set intensity. The current or voltage output to 202 is adjusted.

  A beam splitter 212 is provided in the direction in which the servo laser light passes through the polarization beam splitter 206. The beam splitter 212 transmits half of the incident servo laser light and reflects the other half. Therefore, the servo laser light is divided into two servo laser lights having the same light intensity. The servo laser light that has passed through the beam splitter 212 is applied to the workpiece OB in the Z-axis direction from the opposite direction to the processing laser light. Hereinafter, the servo laser light transmitted through the beam splitter 212 is referred to as servo Z-axis direction laser light. The servo Z-axis direction laser light is parallel light having a diameter larger than the diameter of the workpiece OB, similar to the servo Z-axis direction laser light of the first embodiment, and the optical axis is the processing head. The optical path is positioned so as to coincide with the optical axis of the processing laser beam when the 15 objective lenses 112 are at the origin position.

  Since the servo Z-axis direction laser light is parallel light having a diameter larger than the diameter of the object OB, the laser light that is not blocked by the object OB enters the objective lens 112. In this case, the servo Z-axis direction laser light incident on the objective lens 112 becomes projected light in which a rod-like projection of the workpiece OB is formed at the center when it is received. The servo Z-axis direction laser light incident on the objective lens 112 is condensed, incident on the dichroic mirror 110, and reflected. In the reflection direction of the dichroic mirror 110, a relay lens 116 (imaging lens), a polarizing beam splitter 228, and a photodetector 230 are provided. In the polarization beam splitter 228, the transmission direction is set to the polarization direction of the laser light emitted from the laser light source 202. Therefore, the servo Z-axis direction laser light reflected by the dichroic mirror 110 passes through the relay lens 116 to become parallel light, passes through the polarization beam splitter 228, and enters the light receiving surface of the photodetector 230. Thus, a rod-like projection extending in the X-axis direction, which is a shadow of the workpiece OB, is projected on the light receiving surface of the photodetector 230.

  As shown in FIG. 15, the photodetector 230 includes four light receiving elements having the same square shape in which the light receiving area is divided into four in a cross shape, and is incident on the light receiving areas A, B, C, and D arranged in the clockwise direction. A detection signal proportional to the light intensity is output as a light reception signal (a, b, c, d). The photodetector 230 is arranged so that the cross-shaped dividing line DIV faces the Z-axis direction and the X-axis direction. Hereinafter, among the dividing lines DIV, a dividing line facing in the X-axis direction is referred to as an X-axis direction dividing line DIVX, and a dividing line facing in the Z-axis direction is referred to as a Z-axis direction dividing line DIVZ.

  Further, the servo laser light reflected by the beam splitter 212 is reflected by the first reflecting mirror 214 and the second reflecting mirror 216 and is irradiated on the workpiece OB in the Y-axis direction. Hereinafter, the servo laser light reflected by the beam splitter 212 is referred to as servo Y-axis direction laser light. The servo Y-axis direction laser light is parallel light having a diameter larger than the diameter of the workpiece OB, similar to the servo Y-axis direction laser light of the first embodiment, and the optical axis thereof is the workpiece driving device 50. The optical path is positioned so as to intersect with the rotation axis.

  A third reflection mirror 218 is provided at a position facing the second reflection mirror 216 across the workpiece OB. The servo Y-axis direction laser light reflected by the second reflecting mirror 216 is parallel light having a diameter larger than the diameter of the workpiece OB, and therefore the laser light (projected light) that is not blocked by the workpiece OB. The light enters the third reflection mirror 218. The servo Y-axis direction laser light is reflected by the third reflecting mirror 218 and further reflected by the fourth reflecting mirror 220. In the reflection direction of the fourth reflection mirror 220, an image rotation prism (double prism) 222 and a fifth reflection mirror 224 are provided. The servo Y-axis direction laser light reflected by the fourth reflecting mirror 220 is rotated 90 degrees by the image rotating prism 222. Accordingly, in the servo Y-axis direction laser light emitted from the image rotation prism 222, the projection direction of the workpiece OB is the Z-axis direction. The servo Y-axis laser light emitted from the image rotating prism 222 is reflected by the fifth reflecting mirror 224 to change the traveling direction, and passes through the half-wave plate 226 to change the polarization direction by 90 degrees. The light enters the beam splitter 228. Since the polarization beam splitter 228 has a transmission direction set to the polarization direction of the laser light emitted from the laser light source 202, the incident servo Y-axis direction laser light is reflected by the polarization beam splitter 228. As a result, the servo Y-axis direction laser beam and the servo Z-axis direction laser beam are combined.

  As shown in FIG. 15, a projection S of the workpiece OB by the servo Y-axis direction laser beam and the servo Z-axis direction laser beam is projected onto the photodetector 230. This projection S is the same as the Z-axis direction. The cross shape extends in the X-axis direction. In the photodetector 230, the projection S is divided into two equal parts by the Z-axis direction dividing line DIVZ of the light receiving area when the central axis of the workpiece OB is coincident with the rotation axis of the work driving device 50 when viewed from the Y-axis direction. And the projection S is the X axis of the light receiving area 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 viewed from the Z-axis direction. They are arranged at positions that are equally divided by the direction dividing line DIVX.

  The light reception signals (a, b, c, d) output from the photodetector 230 are input to the Y-axis direction error signal generation circuit 561 and the Z-axis direction error signal generation circuit 571, respectively. In the fifth embodiment, the Y-axis direction error signal generation circuit 561 performs a calculation of ((a + d) − (b + c)) using the received light signals (a, b, c, d), and the calculation result is obtained. Y-axis direction error signal ((a + d)-(b + c)) is output. The magnitude of the Y-axis direction error signal (((a + d)-(b + c)) 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 Z-axis direction error signal generation circuit 571 calculates ((a + b)-(c + d)) using the received light signals (a, b, c, d), and outputs the calculation result as a Z-axis direction error signal (( a + b) − (c + d)) The magnitude of the Z-axis direction error signal ((a + b) − (c + d)) is determined in the Z-axis direction between the center axis of the workpiece OB and the rotation axis of the workpiece driving device 50. It represents the amount of deviation at.

  The Y-axis direction servo circuit 562 starts operating in response to a command from the controller 90, and based on the Y-axis direction error signal (((a + d) − (b + c)) input from the Y-axis direction error signal generation circuit 561, the Y-axis direction servo circuit 562 A Y-axis direction servo signal is generated so that the axial direction error signal (((a + d) − (b + c)) is always zero, and is output to the Y-axis direction drive circuit 563. The Y-axis direction drive circuit 563 is A signal for driving the Y-axis actuator 114y is output based on the direction servo signal, and the objective lens 112 is moved in the Y-axis direction, so that a portion facing the X-axis direction in the cross-shaped projection projected on the photodetector 230 is The position of the objective lens 112 in the Y-axis direction is controlled so that the position of the light-receiving area is equally divided by the X-axis direction dividing line DIVX. Result, the optical axis of the processing laser beam is maintained at a position intersecting the center axis of the workpiece OB.

  Further, the Z-axis direction servo circuit 572 starts to operate in response to a command from the controller 90, and based on the Z-axis direction error signal ((a + b) − (c + d)) input from the Z-axis direction error signal generation circuit 571, The amount of deviation of the workpiece OB in the Z-axis direction is detected, and a Z-axis direction servo signal representing the amount of movement of the objective lens 112 in the Z-axis direction corresponding to the amount of deviation is generated and output to the Z-axis direction drive circuit 573. The Z-axis direction drive circuit 573 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. Therefore, the objective lens 112 is maintained at a position away from the origin position in the Z-axis direction by the amount of deviation of the workpiece OB in the Z-axis direction. For this reason, even if the position of the workpiece OB fluctuates in the Z-axis direction, the objective lens 112 is moved from the origin position by an amount by which the central axis of the workpiece OB deviates from the rotation axis of the workpiece driving device 50. Thus, the focal position of the processing laser beam can always coincide with the surface of the processing object OB.

  Also in this embodiment, the first relay lens 404 and the second relay lens 406 are provided on the optical path of the servo Y-axis direction laser light, and the first relay lens 404 is connected to the relay lens actuator 408 as in the third embodiment. And the Z-axis actuator 114z is driven with the same amount of drive, and Z-axis direction servo control can be performed by closed loop control.

  Further, when the diameter of the beam spot formed on the processing object OB may be large, the focal length of the objective lens 112 can be increased as shown in FIG. A beam splitter 232 may be provided between 112, and the servo Y-axis direction laser light and the servo Z-axis direction laser light emitted from the image rotation prism 222 may be combined by the beam splitter 232. In this case, since it is necessary to make the optical path length from the object OB to the objective lens 112 equal in the laser light in two directions, the relay lenses 234 and 236 are provided. According to this, since the servo Y-axis direction laser beam can also pass through the objective lens 112, Z-axis direction servo control can be performed by closed loop control without providing a relay lens.

  According to the laser processing apparatus of the fifth embodiment described above, not only the effects of the first embodiment are obtained, but also the number of servo laser light sources, servo laser drive circuits, photodetectors, and other optical elements are reduced. Thus, the cost of the apparatus can be reduced.

  In the first embodiment, in the processing of steps S108 and S132 in the laser processing control routine, the irradiation start command or both of the servo Z-axis direction laser drive circuit 240 and the servo Y-axis direction laser drive circuit 340 are given. Although the irradiation stop command is output, in the fifth embodiment, since the servo Z-axis direction laser beam and the servo Y-axis direction laser beam are emitted from the common laser light source 202, the irradiation start is started. The command and the irradiation stop command are output only to the servo laser drive circuit 540 that drives the laser light source 202.

  As mentioned above, although five embodiment of this invention was described, in implementing this invention, it is not limited to the said embodiment, A various deformation | transformation is possible unless it deviates from the objective of this invention.

  For example, in the first embodiment, a configuration is adopted in which the servo Z-axis direction laser light is received by the photodetector 118 via the objective lens 112 that condenses the processing laser light. The optical axis of the laser beam may be slightly shifted from the optical axis of the processing laser beam, and the servo Z-axis direction laser beam 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 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 the 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 circuits 162 and 562 may be detected without providing a displacement sensor in the Y-axis actuator 114y.

  Further, in each of the above embodiments, when the irradiation position of the processing laser beam is moved in the X-axis direction, the workpiece OB is moved in the X-axis direction by the work driving device 50. 10. The unit in which the servo Z-axis direction optical head 20, the servo Y-axis direction optical head 30, and the Y-axis direction light receiving device 40 are integrated may be moved in the X-axis direction.

  In each of the above embodiments, the workpiece OB is rotated about its central axis. However, the workpiece OB is fixed, the machining head 10, the servo Z-axis optical head 20, and the servo Y. The configuration may be such that the axial optical head 30 and the Y-axis light receiving device 40 are rotated around the central axis of the workpiece OB.

  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 orientations of the processing laser beam, servo Z-axis direction laser beam, and servo Y-axis direction laser beam are arbitrarily set under conditions that satisfy the relationship of the X-axis, Y-axis, and Z-axis directions. It can be done.

  OB ... object to be processed, 10, 12, 15 ... processing head, 20 ... Z-axis optical head for servo, 30 ... Y-axis optical head for servo, 40, 43 ... Y-axis light receiving device, 44 ... second Y-axis optical head for servo, 50 ... work drive device, 51 ... moving stage, 52 ... spindle motor, 55 ... feed motor, 56 ... spindle motor control circuit, 57 ... feed motor control circuit, 58 ... moving position detection circuit, 90 ... Controller, 102, 202, 130, 302, 410 ... Laser light source, 110 ... Dichroic mirror, 112 ... Objective lens, 114 ... Focus actuator, 114y ... Y-axis actuator, 114z ... Z-axis actuator, 118, 122, 126, 140, 144, 210, 230, 310, 402, 420, 424 ... Photo data 404, first relay lens, 408, relay lens actuator, 161, 561, Y axis direction error signal generation circuit, 162, 562, Y axis direction servo circuit, 163, 563, Y axis direction drive circuit, 171, 191 , 571 ... Z-axis direction error signal generation circuit, 172, 182, 192, 572 ... Z-axis direction servo circuit, 173, 183, 573 ... Z-axis direction drive circuit, 212 ... Beam splitter, 222 ... Image rotation prism, 240 ... Servo Z-axis direction laser drive circuit, 340... Servo Y-axis direction laser drive circuit, 440... Second servo Z-axis direction laser drive circuit, 540.

Claims (16)

Rotating means for rotating a cylindrical pipe-shaped workpiece relative to the periphery of the workpiece around its central axis;
Laser light for processing is condensed by an objective lens, and laser processing is performed by irradiating the surface of the processing object in the Z-axis direction perpendicular to the X-axis direction that is the central axis direction of the processing object. Laser beam irradiation means for processing;
In a laser processing apparatus comprising: a processing laser beam irradiation position moving unit that moves an irradiation position of the processing laser beam irradiated to the processing object in the X-axis direction;
Servo Z-axis direction laser light whose irradiation direction is set in the Z-axis direction, and servo Y-axis whose irradiation direction is set in the Y-axis direction perpendicular to the Z-axis direction and the X-axis direction Laser beam irradiation means for servo that irradiates a workpiece with a direction laser beam,
The projection or reflected light of the workpiece to be processed of the servo Z-axis laser beam irradiated in the Z-axis direction is received by a light receiving surface, and a light reception signal corresponding to the position of the projection or reflected light on the light receiving surface is received. Z-axis direction laser beam detecting means for outputting;
The projection or reflected light of the workpiece to be processed of the servo Y-axis laser beam irradiated in the Y-axis direction is received by a light-receiving surface, and a light-receiving signal corresponding to the position of the projection or reflected light on the light-receiving surface is received. Y-axis direction laser beam detection means for outputting;
A Y-axis that drives the objective lens in the Y-axis direction so that the optical axis of the processing laser light intersects the central axis of the object to be processed based on the light reception signal output from the Z-axis direction laser light detecting means. Direction servo means;
Z-axis direction for driving the objective lens in the Z-axis direction so that the focal position of the processing laser light coincides with the surface of the object to be processed based on the light reception signal output from the Y-axis direction laser light detection means And a laser processing device. The servo laser light irradiation means is a Z-axis direction irradiation means for irradiating the workpiece in the Z-axis direction with a parallel laser beam having a diameter larger than the diameter of the workpiece as servo Z-axis laser light. Y-axis direction irradiation means for irradiating the processing object in the Y-axis direction with a parallel laser beam having a diameter larger than the diameter of the processing object as Y-axis direction laser light for servo,
The Z-axis direction laser light detecting means receives a projection of the workpiece of the servo Z-axis direction laser light on a light receiving surface, and outputs a light reception signal corresponding to the position of the projection on the light receiving surface,
The Y-axis direction laser light detecting means receives a projection of the workpiece of the servo Y-axis direction laser light on a light receiving surface and outputs a light reception signal corresponding to the position of the projection on the light receiving surface. The laser processing apparatus according to claim 1, wherein: The Z-axis direction irradiation means applies the servo Z-axis direction laser light at a position where the optical axis is the same as that of the processing laser light irradiated from the processing laser light irradiation means, and onto the object to be processed. For irradiation from the direction opposite to the irradiation direction of the processing laser light,
The processing laser beam irradiation means separates the servo Z-axis direction 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 target, and the Z 3. The laser processing apparatus according to claim 2, further comprising a separating optical element that leads to a light receiving surface of the axial laser light detecting means. The servo laser beam irradiating means uses the laser beam condensed to the same extent as the processing laser beam by the objective lens as a servo Z-axis direction laser beam at a position coaxial with the processing laser beam. Z-axis direction irradiation means for irradiating an object in the Z-axis direction, and parallel laser light having a diameter larger than the diameter of the object to be processed is irradiated as Y-axis laser light for servo in the Y-axis direction to the object to be processed Y-axis direction irradiation means
The Z-axis direction laser light detecting means receives the reflected light of the processing target of the servo Z-axis direction laser light on a light receiving surface and outputs a light reception signal corresponding to the position of the reflected light on the light receiving surface. ,
The Y-axis direction laser light detecting means receives a projection of the workpiece of the servo Y-axis direction laser light on a light receiving surface and outputs a light reception signal corresponding to the position of the projection on the light receiving surface. The laser processing apparatus according to claim 1, wherein: The Z-axis direction servo means is
The incident optical path to the light receiving surface of the Y-axis direction laser light detection means includes a relay lens that can move in a direction perpendicular to the optical path, and based on the light reception signal output from the Y-axis direction laser light detection means, The relay lens is driven such that the projection of the workpiece of the servo Y-axis direction laser light is positioned at the center of the light receiving surface of the Y-axis direction laser light detection means, and in conjunction with the driving of the relay lens. The laser processing apparatus according to any one of claims 1 to 4, wherein the objective lens is driven in a Z-axis direction. The Y-axis direction irradiation means is
First Y-axis direction irradiation means for irradiating the processing object in the Y-axis direction with a parallel laser beam having a diameter larger than the diameter of the processing object as a first servo Y-axis direction laser beam;
A second Y-axis direction irradiating means for irradiating the workpiece in the Y-axis direction with a laser beam condensed to a diameter smaller than the diameter of the workpiece as a second servo Y-axis laser beam;
The Y-axis direction laser beam detecting means is
The projection of the processing object of the first servo Y-axis direction laser light irradiated by the first Y-axis direction irradiation means is received by a light receiving surface, and a light reception signal corresponding to the position of the projection on the light receiving surface is output. A first Y-axis direction laser light detector;
The reflected light of the workpiece of the second servo Y-axis direction laser light irradiated by the second Y-axis direction irradiation means is received by a light receiving surface, and a light reception signal corresponding to the position of the reflected light on the light receiving surface is received. A second Y-axis direction laser beam detector for outputting,
The Z-axis direction servo means is
A relay lens movable to a common incident optical path of the first Y-axis direction laser beam detector and the second Y-axis direction laser beam detector in a direction perpendicular to the optical path;
The relay lens is driven so that the projection of the workpiece of the first servo Y-axis direction laser beam is positioned at the center of the light receiving surface of the first Y-axis direction laser beam detector, and the relay lens is driven. Together with the first Z-axis direction servo means for driving the objective lens in the Z-axis direction,
The relay lens is driven so that the reflected light of the workpiece of the second servo Y-axis direction laser light is positioned at the center of the light receiving surface of the second Y-axis direction laser light detector, and the relay lens Second Z-axis direction servo means for driving the objective lens in the Z-axis direction together with driving;
6. An operation switching means for performing an operation switching so that the second Z-axis direction servo means operates after the operation of the first Z-axis direction servo means. The laser processing apparatus according to one item. The servo laser beam irradiation means is
A common laser light source for irradiating the servo Z-axis direction laser beam and the servo Y-axis direction laser beam;
A separation optical path for separating laser light emitted from the laser light source into parallel light having a diameter larger than the diameter of the workpiece and separating the servo Z-axis laser light and the servo Y-axis laser light. Prepared,
The Z-axis direction laser light detection means and the Y-axis direction laser light detection means are
A laser light detector having a light receiving surface divided into a cross shape in a light receiving region, and outputting a light receiving signal corresponding to the light intensity for each light receiving region;
The servo Z-axis direction laser beam and the servo Y-axis direction laser beam are combined so that the projections of the workpieces cross each other in a cross shape and guided to the light receiving surface of the laser light detector. With an optical path,
The Y-axis direction servo means is arranged so that the optical axis of the laser beam for processing intersects the central axis of the workpiece based on the difference between the received light signals in the right and left or upper and lower light receiving areas of the laser light detector. Driving the objective lens in the Y-axis direction;
The Z-axis direction servo means is configured so that the focal position of the processing laser light coincides with the surface of the processing object based on a difference between light receiving signals in the light receiving regions on the top and bottom or the left and right of the laser light detector. The laser processing apparatus according to claim 1, wherein the objective lens is driven in the Z-axis direction.   When the intensity of the reflected light of the processing laser light irradiated on the surface of the workpiece is detected by the processing laser light irradiation means, and the detected reflected light intensity is below a reference value, The laser processing apparatus according to any one of claims 1 to 7, further comprising a focal position inappropriateness determining unit that determines that the focal position of the laser beam is not appropriate. Rotating means for rotating a cylindrical pipe-shaped workpiece relative to the periphery of the workpiece around its central axis;
Laser light for processing is condensed by an objective lens, and laser processing is performed by irradiating the surface of the processing object in the Z-axis direction perpendicular to the X-axis direction that is the central axis direction of the processing object. Laser beam irradiation means for processing;
Applied to a laser processing apparatus comprising: a processing laser light irradiation position moving means for moving the irradiation position of the processing laser light applied to the processing object in the X-axis direction, and the focal position of the processing laser light In the focus servo control method for controlling
Servo Z-axis direction laser light whose irradiation direction is set in the Z-axis direction, and servo Y-axis whose irradiation direction is set in the Y-axis direction perpendicular to the Z-axis direction and the X-axis direction A laser beam irradiation step for servo that irradiates a workpiece with a direction laser beam;
The projection or reflected light of the object to be processed of the servo Z-axis laser light irradiated in the Z-axis direction is received by the light-receiving surface of the Z-axis laser light detector, and the projection or reflected light on the light-receiving surface. Z-axis direction laser beam detection step for outputting a light reception signal according to the position of
The projection or reflected light of the workpiece of the servo Y-axis laser light irradiated in the Y-axis direction is received by the light-receiving surface of the Y-axis laser light detector, and the projection or reflected light on the light-receiving surface. Y-axis direction laser beam detection step for outputting a light reception signal corresponding to the position of
The objective lens is driven in the Y-axis direction so that the optical axis of the processing laser light intersects the central axis of the object to be processed based on the light reception signal output in the Z-axis direction laser light detection step. An axial servo step;
A Z-axis that drives the objective lens in the Z-axis direction so that the focal position of the processing laser light coincides with the surface of the object to be processed based on the light reception signal output in the Y-axis direction laser light detection step. A focus servo control method for a laser processing apparatus, comprising: a direction servo step. The servo laser beam irradiation step includes a Z-axis direction irradiation step of irradiating the workpiece with the parallel laser beam having a diameter larger than the diameter of the workpiece as the servo Z-axis direction laser beam in the Z-axis direction; A Y-axis direction irradiation step of irradiating the processing target object in the Y-axis direction with a parallel laser beam having a diameter larger than the diameter of the processing target object as servo Y-axis direction laser light,
The Z-axis direction laser light detecting step receives a projection of the workpiece of the servo Z-axis direction laser light on a light-receiving surface of the Z-axis direction laser light detector, and at the position of the projection on the light-receiving surface. According to the received light signal,
The Y-axis direction laser beam detecting step receives the projection of the workpiece of the servo Y-axis direction laser beam on the light-receiving surface of the Y-axis direction laser beam detector, and at the position of the projection on the light-receiving surface. 10. The focus servo control method for a laser processing apparatus according to claim 9, wherein a corresponding light reception signal is output. In the Z-axis direction irradiation step, the servo Z-axis direction laser light is applied to the processing object at a position where the optical axis is the same as the processing laser light irradiated from the processing laser light irradiation means. For irradiation from the direction opposite to the irradiation direction of the processing laser light,
In the Z-axis direction laser beam detecting step, the servo Z-axis direction laser beam incident on the optical path is obtained by a separation optical element provided in the middle of the optical path for irradiating the processing laser beam on the workpiece. The focus servo control method for a laser processing apparatus according to claim 10, wherein the focus servo control method for the laser processing apparatus is separated from the optical path and led to the light receiving surface of the Z-axis direction laser light detector. In the servo laser beam irradiation step, the laser beam focused to the same extent as the processing laser beam by the objective lens is used as a servo Z-axis direction laser beam at a position coaxial with the processing laser beam. Irradiating an object in the Z-axis direction, and irradiating the object to be processed in the Y-axis direction as a servo Y-axis laser beam having a diameter larger than the diameter of the object to be processed. Y-axis direction irradiation step to
The Z-axis direction laser light detection step receives the reflected light of the workpiece of the servo Z-axis direction laser light on the light-receiving surface of the Z-axis direction laser light detector, and detects the reflected light on the light-receiving surface. Outputs the received light signal according to the position,
The Y-axis direction laser beam detecting step receives the projection of the workpiece of the servo Y-axis direction laser beam on the light-receiving surface of the Y-axis direction laser beam detector, and at the position of the projection on the light-receiving surface. 10. The focus servo control method for a laser processing apparatus according to claim 9, wherein a corresponding light reception signal is output. The Z-axis direction servo step includes:
A relay lens that is movable in a direction perpendicular to the optical path is provided on the incident optical path to the light receiving surface of the Y-axis direction laser light detector, and based on the light-receiving signal output from the Y-axis direction laser light detector. The relay lens is driven so that the projection of the workpiece of the Y-axis laser light for servo is located at the center of the light receiving surface of the Y-axis laser light detector, and the driving of the relay lens is performed. 13. The focus servo control method for a laser processing apparatus according to claim 9, wherein the objective lens is driven in the Z-axis direction. The Y-axis direction irradiation step includes:
A first Y-axis direction irradiation step of irradiating the workpiece in the Y-axis direction with a parallel laser beam having a diameter larger than the diameter of the workpiece as a first servo Y-axis laser beam;
A second Y-axis direction irradiation step of irradiating the processing object in the Y-axis direction with a laser beam condensed to a diameter smaller than the diameter of the processing object as a second servo Y-axis direction laser beam,
The Y-axis direction laser beam detection step includes:
The projection of the object to be processed by the first servo Y-axis direction laser light irradiated in the first Y-axis direction irradiation step is received by the light-receiving surface of the first Y-axis direction laser light detector, and the projection of the projection on the light-receiving surface is performed. A first Y-axis direction laser beam detection step for outputting a light reception signal corresponding to the position;
The reflected light of the workpiece of the second servo Y-axis direction laser light irradiated in the second Y-axis direction irradiation step is received by the light-receiving surface of the second Y-axis direction laser light detector, and the reflection on the light-receiving surface. A second Y-axis direction laser light detection step for outputting a light reception signal corresponding to the position of the light,
The Z-axis direction servo step includes:
A relay lens movable in a direction perpendicular to the optical path is provided on a common incident optical path of the first Y-axis direction laser light detector and the second Y-axis direction laser light detector, and the first servo Y-axis The relay lens is driven so that the projection of the workpiece of the directional laser light is located at the center of the light receiving surface of the first Y-axis direction laser light detector, and the objective lens is moved together with the driving of the relay lens. A first Z-axis servo step for driving in the Z-axis direction;
After the first Z-axis direction servo step, the reflected light of the workpiece of the second servo Y-axis direction laser light is positioned at the center of the light receiving surface of the second Y-axis direction laser light detector. 14. A second Z-axis direction servo step for driving the relay lens and driving the objective lens in the Z-axis direction in combination with the driving of the relay lens. A focus servo control method for the laser processing apparatus according to the item. In the servo laser light irradiation step, the laser light emitted from one laser light source is converted into parallel light having a diameter larger than the diameter of the workpiece, the servo Z-axis laser light and the servo Y-axis direction. Separated into laser light,
The Z-axis direction laser light detection step and the Y-axis direction laser light detection step include:
The servo Z-axis direction laser beam and the servo Y-axis direction laser beam are combined so that the projections of the workpieces cross in a cross shape, and the light receiving region is divided into cross shapes. Led to the light-receiving surface of the laser detector that outputs a light-receiving signal corresponding to the light intensity for each light-receiving region,
In the Y-axis direction servo step, the optical axis of the processing laser beam intersects the central axis of the processing object based on the difference between the received light signals in the left and right or upper and lower light receiving regions of the laser light detector. Driving the objective lens in the Y-axis direction;
In the Z-axis direction servo step, based on the difference between the received light signals in the upper and lower or left and right light receiving regions of the laser light detector, the focal position of the processing laser light coincides with the surface of the processing object. The focus servo control method for a laser processing apparatus according to claim 9, wherein the objective lens is driven in the Z-axis direction.   When the processing laser beam irradiation step detects the intensity of reflected light of the processing laser beam irradiated on the surface of the processing object, and the detected reflected light intensity is below a reference value, the processing laser beam is irradiated. 16. The focus servo control method for a laser processing apparatus according to claim 9, further comprising a focus position inappropriateness determining step for determining that the focal position of the laser beam is not appropriate.

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