Patent Publication Number: US-2023158604-A1

Title: Laser processing apparatus and relationship determination method

Description:
TECHNICAL FIELD 
     The present invention relates to a laser processing apparatus that performs laser machining. 
     BACKGROUND ART 
     In recent years, a laser machining apparatus has been proposed in which a cylindrical irradiation region extending in the optical axis direction of a laser is displaced in a direction intersecting the optical axis to form a machining surface on the surface side of a sample through which the irradiation region passes (Patent Document 1). Machining by means of this apparatus is an excellent machining method in that mechanical damage can be reduced and a machining surface can be smoothly formed as compared with mechanical machining methods. 
     CITATION LIST 
     Patent Document 
     Patent Document 1: JP 6562536 B2 
     SUMMARY OF THE INVENTION 
     Problem to be Solved by the Invention 
     This type of machining method is also used in machining a corner portion in a sample formed by a plurality of adjacent surfaces, examples of which include a cutting tool having a corner portion formed by a rake surface and a flank surface. Specifically, laser irradiation is performed such that the optical axis extends along the direction of spread of the rake surface or the flank surface and the laser is displaced to form a new rake or flank surface in the corner portion as a machining surface. 
     As for this apparatus, machining is conducted when the laser irradiation region and the corner portion overlap. Accordingly, for efficient machining, a positional relationship is desirable in which the tip of the corner portion reaches the irradiation region (e.g. the outer periphery of the irradiation region or the optical axis in the irradiation region) prior to the machining. However, making such a positional relationship determination requires many additional components for that purpose only (e.g. laser and sensor) and entails a problematic increase in required cost. 
     The invention has been made to solve such a problem, and an object of the invention is to provide a technique with which the positional relationship between a laser and a corner end can be determined at a lower cost than in the related art in a laser machining apparatus. 
     Means for Solving Problem 
     A first aspect for solving the above problem is a laser processing apparatus configured to perform laser machining on a corner portion of a sample by causing the corner portion to relatively approach a laser, the laser being emitted such that an optical axis of the laser extends in a predetermined direction, the corner portion being formed by a plurality of adjacent surfaces of the sample, the laser processing apparatus including: a detection unit provided at a position at least outside an irradiation region of the laser, the irradiation region extending in a tubular shape in a plan view intersecting the optical axis, the detection unit being configured to detect intensity of light reaching the position; approach control means for controlling an actuator relatively displacing the sample along a direction intersecting the optical axis such that the sample relatively approaches the optical axis; value acquisition means for acquiring the intensity of the light defined as a value detected by the detection unit in a predetermined positional relationship in which a tip of the corner portion has reached the irradiation region; and relationship determination means for determining a positional relationship between the laser and the sample based on the intensity of the light detected by the detection unit while the sample relatively approaches the optical axis. When the detection unit detects the intensity of the light as a value the same as the value acquired by the value acquisition means or within a predetermined threshold range, the relationship determination means determines that the predetermined positional relationship is established. 
     This aspect may be as described in the following second aspect. 
     In the second aspect, the approach control means controls the actuator such that the sample relatively approaches the optical axis until the relationship determination means determines that the tip of the corner portion is in the predetermined positional relationship in which the tip has reached the irradiation region. 
     These aspects may be as described in the following third aspect. 
     In the third aspect, in a case where the detection unit detects the intensity of the light as a value outside the predetermined threshold range with the value acquired by the value acquisition means, the relationship determination means determines that the tip of the corner portion is not in the predetermined positional relationship in which the tip has reached the irradiation region, and the approach control means controls the actuator such that the sample relatively approaches the optical axis until the relationship determination means determines that the tip is in the positional relationship after the relationship determination means determines that the tip of the corner portion is not in the predetermined positional relationship in which the tip has reached the irradiation region. 
     The second and third aspects may be as described in the following fourth aspect. 
     In the fourth aspect, the actuator control by the approach control means, the light intensity acquisition by the value acquisition means, and the positional relationship determination by the relationship determination means are performed each time the corner portion is machined with the laser. 
     Each of the above aspects may be as described in the following fifth aspect. 
     In the fifth aspect, the detection unit is provided at the position at least outside the irradiation region in the plan view intersecting the optical axis with the position in a region opposite to a light source of the laser in a case where a space extending along the optical axis is divided into two by the sample. 
     A sixth aspect for solving the above problem is a position determination method including: a detection procedure of detecting intensity of light reaching a position at least outside an irradiation region of a laser, the irradiation region extending in a tubular shape in a plan view intersecting an optical axis of the laser having the optical axis extending in a predetermined direction; an approach control procedure of controlling an actuator relatively displacing a sample where a corner portion is formed by a plurality of adjacent surfaces of the sample along a direction intersecting the optical axis with the corner portion directed to the laser side such that the sample relatively approaches the optical axis; a value acquisition procedure of acquiring the intensity of the light defined as a value detected by the detection unit in a predetermined positional relationship in which a tip of the corner portion has reached the irradiation region; and a relationship determination procedure of determining a positional relationship between the laser and the sample based on the intensity of the light detected by the detection procedure while the sample relatively approaches the optical axis. When detecting the intensity of the light as a value the same as the value acquired in the value acquisition procedure or within a predetermined threshold range in the detection procedure, determining that the predetermined positional relationship is established. 
     Effect of the Invention 
     According to each of the aspects, the positional relationship between the laser and the sample can be determined based on a light intensity detection result simply by being capable of detecting the light intensity at a position outside the laser irradiation region. Accordingly, it is not necessary to provide a number of additional device configurations for the determination and the cost of positional relationship determination can be reduced. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a block diagram illustrating an overall configuration of a laser machining apparatus; 
         FIG.  2    is a block diagram illustrating a configuration of an irradiation unit; 
         FIG.  3    is a diagram illustrating a positional relationship between a laser irradiation region and a detection unit; 
         FIG.  4    is a flowchart illustrating a machining processing procedure; 
         FIG.  5    is a diagram illustrating an energy distribution in a laser; 
         FIG.  6    is a flowchart illustrating a relationship determination processing procedure; and 
         FIG.  7    is a graph illustrating a light intensity transition corresponding to a sample displacement amount. 
     
    
    
     MODE(S) FOR CARRYING OUT THE INVENTION 
     An embodiment for carrying out the invention will be described in detail with reference to the drawings. 
     (1) Apparatus Configuration 
     As illustrated in  FIG.  1   , a laser machining apparatus  1  includes an irradiation unit  10  performing laser irradiation such that an optical axis extends in a predetermined direction (up-down direction in  FIG.  1   ), a holding portion  20  for holding a sample  100 , an irradiation unit displacement mechanism  30  for displacing the irradiation unit  10  with respect to the sample  100 , a holding portion displacement mechanism  40  for displacing the holding portion  20  with respect to the laser, a detection unit  50  detecting the intensity of light at a predetermined position, and a control unit  60  controlling the operation of the entire laser machining apparatus  1 . 
     As illustrated in  FIG.  2   , the irradiation unit  10  includes, for example, an oscillator  11  outputting a pulsed laser, a vibration adjuster  13  adjusting the order of the frequency of the laser, a polarizing element  14  performing polarization state adjustment, an attenuator (ATT)  15  performing laser output adjustment, and a beam expander (EXP)  17  for laser diameter adjustment. The irradiation unit  10  is configured such that the laser passing through the components is output via an optical lens  19  and performs laser irradiation with the optical axis directed in a predetermined direction (Z-axis direction in the present embodiment). An Nd:YAG pulsed laser is used for the oscillator  11 . 
     The above configuration includes the single optical lens  19 . An alternative configuration may include a set of optical lenses disposed at predetermined intervals and a mechanism for adjusting the distance between the optical lenses. 
     The holding portion  20  is a rod-shaped member extending in a direction intersecting the optical axis of the laser (left-right direction in  FIG.  1   ) and is configured so as to be capable of holding the sample  100  at the tip of the holding portion  20 . The sample  100  is held in a positional relationship in which an end portion of the sample  100  protrudes from the tip of the holding portion  20 . 
     The irradiation unit displacement mechanism  30  includes a mechanism main body  31  as an actuator displaced in a predetermined direction with the irradiation unit  10  attached and a drive unit  33  operating the mechanism main body  31  based on a command from the outside. In the present embodiment, the mechanism main body  31  is configured to displace the irradiation unit  10  in a direction intersecting the optical axis of the laser (direction from the front to the back of the paper surface in  FIG.  1   ). 
     The holding portion displacement mechanism  40  includes a mechanism main body  41  as an actuator displaced in a predetermined direction with the holding portion  20  attached and a drive unit  43  operating the mechanism main body  41  based on a command from the outside. In the present embodiment, the mechanism main body  41  is configured to displace the holding portion  20  in the direction in which the holding portion  20  extends. 
     As illustrated in  FIG.  3   , the detection unit  50  is an optical sensor provided at a position at least outside an irradiation region  200  when viewed from a plane intersecting an optical axis  210  (plane of the broken line in  FIG.  3   ) with the position in the region opposite to the irradiation unit  10  in a case where the space extending along the optical axis  210  is divided into two at the position of the sample  100  (region below the holding portion  20  in  FIG.  3   ). The detection unit  50  detects the intensity of light that reaches this position (hereinafter, also referred to as “light intensity”). In the present embodiment, a line sensor in which a plurality of light receiving elements are disposed in a direction away from the optical axis  210  is adopted as the detection unit  50 . The detection unit  50  is disposed at a position that diffracted light is capable of reaching with sufficient intensity in the relationship determination processing to be described later. 
     The control unit  60  is a computer controlling, for example, the laser irradiation that is performed by the irradiation unit  10 , the displacement of the irradiation unit  10  that is performed by the irradiation unit displacement mechanism  30 , and the displacement of the holding portion  20  that is performed by the holding portion displacement mechanism  40  by means of control commands to the respective parts. 
     As for the sample  100 , a corner portion  110  is formed by a plurality of adjacent surfaces. In the present embodiment, the sample  100  is a cutting tool made of cemented carbide, one surface of the tool is a rake surface, and the other is a flank surface. 
     By installing the corner portion  110  of the sample  100  toward the laser irradiation region  200  side, the surface formed by the corner portion  110  is disposed along the optical axis  210 . 
     As for the laser machining apparatus  1  configured as described above, a machining surface can be formed on the corner portion  110  by performing laser irradiation such that the optical axis  210  extends along the plane direction formed by the corner portion  110  and displacing the laser. 
     (2) Procedure of Processing by Control Unit  60   
     (2-1) Machining Processing 
     Hereinafter, the procedure of “machining processing” that the control unit  60  executes with a program stored in a built-in memory  61  will be described with reference to  FIG.  4   . This machining processing is executed after the sample  100  is held by the holding portion  20  and positioned and is started when a start command is received from an interface (operation device or communication device, not illustrated). 
     This machining processing is performed after the holding portion  20  holding the sample  100  is positioned at a predetermined reference position and is started when the start command is received from the interface (operation device or communication device, not illustrated). Here, with the holding portion  20  positioned, the tip of the corner portion  110  in the sample  100  reaches the irradiation region  200  in terms of positional relationship. Specifically assumed as the positional relationship is, for example, the tip of the corner portion  110  overlapping the outer periphery of the irradiation region  200 , overlapping the irradiation region  200  by a predetermined range, or reaching the optical axis  210 . 
     When this machining processing is started, first, machining processing setting information pre-stored in the built-in memory  61  is read (s 110 ). This setting information is information preset by a user and includes an output P 0  [w] of the laser emitted by the irradiation unit  10 , a machining threshold Pth [w] corresponding to the material properties of the sample  100  installed in the holding portion  20 , and coordinate information defining each of one or more machining surfaces to be formed on the sample  100 . 
     The laser output is determined such that a machinable region having an energy distribution equal to or higher than the machining threshold Pth [w] required for the laser machining of the sample  100  is formed inside the irradiation region  200 , which extends in a tubular shape along the optical axis  210 , in the laser. The laser output is an output level corresponding to the material properties of the sample  100 . In addition, the coordinate information determines the position of the machining surface in the sample  100  as three-dimensional coordinates with reference to a predetermined origin. 
     The length of the machinable region along the optical axis direction is required to be longer than at least that on the machining surface of the sample  100 . Accordingly, the output of the laser is set in view of the relationship with the coordinate information such that this length is realized. Specifically, the output level P 0  of the laser is a value larger than the machining threshold Pth (P 0 &gt;Pth). 
     Next, the machinable region is set based on the setting information read in s 110  (s 120 ). Here, an energy distribution P(r) at each position on the optical axis of the laser is calculated based on the laser output P 0  [w] and the machining threshold Pth [w] among the setting information read in s 110 , and then a tubular region formed by connecting a planar region with a predetermined radius rth, which has an energy distribution equal to or higher than the machining threshold Pth, along the optical axis is specified (see  FIG.  5   ). Then, the radius rth in this region is specified as a parameter that defines the machinable region. 
     It has been experimentally confirmed that this machinable region changes from a linear tubular shape to a constricted tubular shape decreasing in diameter toward the focal position as the laser output PO increases. In other words, the outer periphery of the machinable region changes from a linear shape to a curved shape as the laser output P 0  increases. Accordingly, as for the laser output P 0 , a value corresponding to a shape required for the machining surface is selectively included in the setting information. 
     Next, it is checked whether or not there is an unformed machining surface (s 130 ). Here, it is determined that there is an unformed machining surface in a case where the coordinate information that has not been referred to since the start of this machining processing is left in the coordinate information in the setting information read in s 110 . 
     In a case where it is determined in s 130  that there is an unmachined machining surface (s 130 : YES), any coordinate information that is not referred to in the subsequent processing is extracted and the machining surface defined by this coordinate information is set as a target machining surface to be formed in the subsequent processing (s 140 ). 
     Next, the relationship determination processing to be described later is executed (s 150 ). Here, it is determined whether or not the tip of the corner portion  110  reaches the irradiation region  200  in the predetermined positional relationship at this point in time and the positional relationship between the tip of the corner portion  110  and the irradiation region  200  is corrected such that such a positional relationship is achieved. 
     Next, laser irradiation by means of the irradiation unit  10  is started (s 160 ). Here, the control unit  60  commands the irradiation unit  10  to perform laser irradiation by which the machinable region set in s 120  can be formed and the laser irradiation by means of the irradiation unit  10  is started with this command received. In this manner, the laser is emitted such that the optical axis  210  extends in a predetermined direction (up-down direction in  FIG.  1    in the present embodiment). 
     Next, the holding portion displacement mechanism  40  causes the sample  100  to approach the irradiation region  200  in the laser emitted by the irradiation unit  10  (s 170 ). Here, a control command is given to the holding portion displacement mechanism  40  such that the sample  100  approaches the irradiation region  200  side. In response to this control command, the holding portion displacement mechanism  40  displaces the sample  100  until the sample  100  and the machinable region overlap. 
     The sample  100  and the machinable region overlap by causing the irradiation region  200  to approach the sample  100  until the distance between the optical axis of the laser and the machining surface of the sample  100  (distance along the left-right direction in  FIG.  1    in the present embodiment) corresponds to the radius rth defining the machinable region of the irradiation region  200  based on the radius rth defined in s 120  and the coordinate information on the machining surface set in s 140 . 
     Next, the irradiation unit displacement mechanism  30  performs scanning with the irradiation region  200  in the laser emitted by the irradiation unit  10  along the corner portion  110  of the sample  100  (s 180 ). Here, a control command is given to the irradiation unit displacement mechanism  30  such that the irradiation unit  10  is displaced along the corner portion  110 . In response to this control command, the irradiation unit displacement mechanism  30  starts displacement from a predetermined reference position, displaces the irradiation unit  10  until the irradiation region  200  passes through the entire machining surface, and then returns to the reference position. The scanning of the corner portion  110  by means of the irradiation region  200  here is repeated a plurality of times. 
     Through s 170  to s 180  in this manner, the corner portion  110  of the sample  100  is machined by the machinable region of the irradiation region  200 . 
     After s 180 , the laser irradiation by means of the irradiation unit  10  started in s 160  ends (s 190 ). Here, the control unit  60  commands the irradiation unit  10  to end the irradiation and the irradiation unit  10  ends the laser irradiation with this command received. 
     After finishing s 190 , the process returns to s 130 . Subsequently, s 130  to s 190  are carried out until there is no unmachined machining surface. Subsequently, this machining processing ends in a case where it is determined in s 130  that there is no unmachined machining surface (s 130 : NO). 
     (2-2) Relationship Determination Processing 
     The procedure of “relationship determination processing” executed by s 150  of the machining processing will be described below with reference to  FIG.  6   . 
     When this relationship determination processing is started, the irradiation region  200  is set first (s 210 ). Here, a value smaller than the machining threshold Pth is set as the laser output level P 0  based on the setting information read in s 110  (P 0 &lt;Pth). 
     Next, laser irradiation by means of the irradiation unit  10  is started (s 220 ). Here, the control unit  60  commands the irradiation unit  10  to perform laser irradiation by which the irradiation region  200  set in s 210  can be formed and the laser irradiation by means of the irradiation unit  10  is started with this command received. In this manner, the laser is emitted such that the optical axis  210  extends in a predetermined direction (up-down direction in  FIG.  1    in the present embodiment). 
     Next, information indicating a predetermined light intensity is acquired as a comparative value used in the subsequent processing (s 230 ). Acquired here is information indicating the light intensity defined as being detected by the detection unit  50  in a case where the tip of the corner portion  110  reaches the irradiation region  200  in terms of positional relationship with respect to the laser irradiation region  200  set in s 210 . 
     In the present embodiment, the light intensity actually detected by the detection unit  50  in a case where the positional relationship between the irradiation region  200  and the tip of the corner portion  110  is changed with respect to each of the irradiation regions  200  having a plurality of assumed patterns is pre-recorded as information in the built-in memory  61  and the information indicating the light intensity as the comparative value is acquired by reading the information matching in positional relationship from the information recorded in this manner. The information read here matches the current positional relationship defined by the initial positional relationship at a point in time when the holding portion  20  is positioned (e.g. positional relationship of the tip of the corner portion  110  overlapping the outer periphery of the irradiation region  200 , overlapping the irradiation region  200  by a predetermined range, or reaching the optical axis  210 ) and the amount of displacement of the sample  100  in the machining processing (s 170  in particular). 
     In the present embodiment, not only the total value or the average value of the light intensities (W) respectively output from the light receiving elements of the line sensor adopted as the detection unit  50  but also the distribution along the disposition direction of the light receiving element in the line sensor (value of each light receiving element position) are detected and recorded as the light intensity in each positional relationship. 
     Next, the light intensity detected by the detection unit  50  is acquired (s 240 ). Here, not only the total value or the average value of the light intensities (W) respectively output from the light receiving elements of the line sensor adopted as the detection unit  50  but also the distribution along the disposition direction of the light receiving element in the line sensor (value of each light receiving element position) are detected as the actual light intensity in the current positional relationship. 
     Next, the positional relationship between the laser and the sample  100  is determined based on the light intensity acquired in s 230  and s 240  (s 250 ). Here, based on the actual light intensity acquired in s 240  being the same as the light intensity that is the comparative value acquired in s 230  or within a predetermined threshold range, it is determined that the tip of the corner portion  110  reaches the irradiation region  200  in the predetermined positional relationship at that point in time. “Predetermined positional relationship” here means that the positional relationship between the tip of the corner portion  110  and the irradiation region  200  matches the initial positional relationship at a point in time when the holding portion  20  is positioned. 
     In a case where the light intensity is a value of each light receiving element position in the line sensor, the light intensities at the same position are compared and it is checked whether or not all the values are the same or within a predetermined threshold range. 
     Here, the actual light intensity being the same as the light intensity that is the comparative value or within a predetermined threshold range, that is, the actually detected light intensity being the same as or close to the light intensity assumed in the same positional relationship means a state where the machining of the corner portion  110  has not been sufficiently carried out in the machining processing executed so far (machining being yet to be performed in the present embodiment) or a state where the positional relationship is corrected in the process to be described later. 
     The actual light intensity being outside the predetermined threshold range of the light intensity that is the comparative value, that is, the actually detected light intensity not being close to the light intensity assumed in the same positional relationship means that the machining of the corner portion  110  has been sufficiently carried out in the machining processing executed so far. In this state, the positional relationship between the irradiation region  200  and the tip of the corner portion  110  is changed as a result of the tip of the corner portion  110  retracting toward the outside of the irradiation region  200 , and thus the actual light intensity is outside the predetermined threshold range of the light intensity that is the comparative value. 
     Next, in a case where the actual light intensity is not close to the light intensity that is the comparative value as a result of the determination by s 250  (s 260 : NO), the holding portion displacement mechanism  40  causes the sample  100  to approach the irradiation region  200  in the laser emitted by the irradiation unit  10  (s 270 ). Here, a control command is given to the holding portion displacement mechanism  40  such that the sample  100  approaches the irradiation region  200  side. In response to this control command, the holding portion displacement mechanism  40  displaces the sample  100  by a predetermined unit distance. The unit distance in this displacement is sufficiently smaller than the amount of displacement of the sample  100  in the machining processing (s 170  in particular). 
     After finishing s 270 , the process returns to s 240 . Subsequently, s 240  to s 270  are repeated until it is determined that the actual light intensity is the same as or close to the light intensity that is the comparative value. In this manner, in this relationship determination processing, the sample  100  approaches the optical axis  210  after the first determination that the actual light intensity is not the same as or close to the light intensity that is the comparative value, and thus the positional relationship between the laser and the sample  100  is gradually corrected. As a result, the positional relationship between the tip of the corner portion  110  and the irradiation region  200  matches the initial positional relationship at a point in time when the holding portion  20  is positioned. 
     In a case where it is determined as a result of the determination by s 250  that the actual light intensity is the same as or close to the light intensity that is the comparative value (s 260 : YES), the laser irradiation by means of the irradiation unit  10  started in s 220  ends (s 280 ). Here, the control unit  60  commands the irradiation unit  10  to end the irradiation and the irradiation unit  10  ends the laser irradiation with this command received. 
     In this manner, after finishing s 280 , the relationship determination processing ends and the process returns to the machining processing. 
     s 230  described above is the value acquisition means in the invention, s 240  is the detection procedure in the invention, s 260  and s 270  are the approach control means and the approach control procedure in the invention, and s 250  is the position determination means and the position determination procedure in the invention. 
     (3) Modification Examples 
     Although an embodiment of the invention has been described above, the invention is not limited to the above embodiment. It is a matter of course that various forms can be taken insofar as the forms belong to the technical scope of the invention. 
     For example, in the configuration exemplified in the above embodiment, the sample  100  side is displaced along a direction intersecting the optical axis  210 . In an alternative configuration, the optical axis  210  side (that is, laser) may be displaced with respect to the sample  100 . 
     In the configuration exemplified in the above embodiment, the relationship determination processing is executed by the control unit  60  of the laser machining apparatus  1 . In an alternative configuration, this relationship determination processing may be executed by an apparatus different from the laser machining apparatus  1 . It is conceivable that the apparatus for this purpose includes the irradiation unit  10 , the holding portion  20 , the holding portion displacement mechanism  40 , the detection unit  50 , and the control unit  60  that executes the relationship determination processing. 
     In the configuration exemplified in the above embodiment, the light intensity that is a comparative value is acquired by reading pre-recorded information in s 230  of the relationship determination processing. In an alternative configuration, the light intensity that is a comparative value may be acquired as a value calculated from parameters such as the energy distribution in the laser irradiation region  200 , the positional relationship between the detection unit  50  and the corner portion  110 , and the shape of the corner portion  110 . 
     In the configuration exemplified in the above embodiment, the relationship determination processing is executed and the positional relationship between the laser and the sample  100  is determined every time a machining surface is formed on the sample  100  in the machining processing. However, the timing of determination of the positional relationship between the laser and the sample  100  is not limited thereto and it is conceivable to determine the positional relationship at, for example, each scan of the sample  100  with the irradiation region  200 . Conceivable in this case is a configuration in which the relationship determination processing is executed before or after the scan in s 180 . 
     In addition, the positional relationship between the laser and the sample  100  may be determined during the actual machining in the machining processing. Conceivable in this case is a configuration in which the relationship determination processing is executed in parallel during the scan in s 180 . 
     In addition, the timing of determination of the positional relationship between the laser and the sample  100  may be irrelevant to the machining processing. In this case, the relationship determination processing may be executed at any timing with a start command received. 
     In the configuration exemplified in the above embodiment, the actual light intensity is compared to a comparative value in determining the positional relationship in the relationship determination processing. In an alternative configuration, the time-axis transitions of the actual light intensity and the light intensity that is a comparative value may be compared in determining the positional relationship. 
     The following is a specific example, in which “positional relationship in which the tip of the corner portion  110  reaches the optical axis  210 ” is adopted as the initial positional relationship at a point in time when the holding portion  20  is positioned. s 240  to s 270  of the relationship determination processing are carried out using the light intensity in the process in which the tip of the corner portion  110  reaches the optical axis  210  from the outside of the irradiation region  200  as a comparative value. It has been experimentally confirmed that a section where the light intensity increases at a certain rate or more (side to the left of the one-dot chain line in  FIG.  7   ) and a section where the rate of increase is less than a certain rate (side to the right of the one-dot chain line in  FIG.  7   ) arrive in order as illustrated in  FIG.  7    after the tip of the corner portion  110  reaches and overlaps the irradiation region  200  in this process and the tip of the corner portion  110  reaches the optical axis  210  when the latter section arrives. Accordingly, in this case, it is determined that the tip of the corner portion  110  reaches the irradiation region  200  in the predetermined positional relationship at that point in time based on the actual light intensity being the same as the light intensity that is a comparative value or within a predetermined threshold range in terms of the degree of increase. 
     (4) Actions and Effects 
     In the above embodiment, the positional relationship between the laser and the sample  100  can be determined based on a light intensity detection result simply by being capable of detecting the light intensity at a position outside the laser irradiation region  200 . Accordingly, it is not necessary to provide a number of additional device configurations for the determination and the cost of positional relationship determination can be reduced. 
     In the laser machining apparatus  1  of the above embodiment, the positional relationship with the irradiation region  200  can be determined and corrected in real time in parallel with the machining of the sample  100 . 
     INDUSTRIAL APPLICABILITY 
     The invention can be used in determining a laser-sample positional relationship at a low cost without providing a number of additional device configurations. 
     EXPLANATIONS OF LETTERS OR NUMERALS 
       1  LASER MACHINING APPARATUS 
       10  IRRADIATION UNIT 
       11  OSCILLATOR 
       13  VIBRATION ADJUSTER 
       14  POLARIZING ELEMENT 
       15  ATTENUATOR (ATT) 
       17  BEAM EXPANDER (EXP) 
       19  OPTICAL LENS 
       20  HOLDING PORTION 
       30  IRRADIATION UNIT DISPLACEMENT MECHANISM 
       31  MECHANISM MAIN BODY 
       33  DRIVE UNIT 
       40  HOLDING PORTION DISPLACEMENT MECHANISM 
       41  MECHANISM MAIN BODY 
       43  DRIVE UNIT 
       50  DETECTION UNIT 
       60  CONTROL UNIT 
       61  BUILT-IN MEMORY 
       100  SAMPLE 
       110  CORNER PORTION 
       200  IRRADIATION REGION 
       210  OPTICAL AXIS