JP2013094816A - Focusing device and laser processing unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform auto-focusing, regardless of the reflecting state of a processing surface of a workpiece, without the switching of a measuring system of a displacement sensor or replacement of the displacement sensor.SOLUTION: A focusing unit including an error amplifier 213 and a motor driver 214 adjusts the focal position of an objective lens 217, when a probe light is regularly reflected by the processing surface of the workpiece 102, based on a measurement result measured by the displacement sensor 211 using a reflected light of the regularly-reflected probe light which is diffusely reflected by a diffusive reflecting plate 212 and then reflected by the processing surface. The focusing unit adjusts the focal position of the objective lens 217, when the probe light is regularly reflected by the processing surface, based on a measurement result measured by the displacement sensor 211 using the diffusely-reflected light. The invention can be applied to a laser processing unit.

Description

  The present invention relates to a focus adjustment apparatus and a laser processing apparatus, and more particularly to a focus adjustment apparatus and a laser processing apparatus equipped with an autofocus function.

  When laser processing of a thin film solar cell panel is performed, the distance between the objective lens that emits the laser beam for processing and the processing surface fluctuates due to bending of the glass substrate on which the thin film is deposited. It is necessary to make the position follow the machining surface. For this reason, the laser processing apparatus is usually equipped with an autofocus function for automatically adjusting the focal position of the objective lens in accordance with the vertical fluctuation of the processing surface.

  Also, to control such an autofocus function, irradiate a workpiece such as a thin-film solar cell panel with probe light, which is a laser beam for measurement, and measure the displacement of the workpiece or the distance to the workpiece by reflected light from the workpiece. A displacement sensor is often used (see, for example, Patent Document 1).

JP 2005-111534 A

  However, the displacement sensor measurement method is divided into two types: a regular reflection method using regular reflection light from the object to be measured and a diffuse reflection method using diffuse reflection light from the object to be measured. For this reason, it is necessary to switch the measurement method of the displacement sensor or replace the displacement sensor depending on whether the work surface of the workpiece is a regular reflection surface or a diffuse reflection surface.

  The present invention has been made in view of such a situation, and regardless of the state of reflection on the work surface of the workpiece, the autofocus is performed without switching the displacement sensor measurement method or replacing the displacement sensor. It is something that can be done.

  A laser processing apparatus according to a first aspect of the present invention is a focus adjustment apparatus for a laser processing apparatus, which includes an objective lens that emits laser light for processing, and measurement light that is displaced or reflected by the reflected light. Based on the displacement sensor that measures the distance to the object, the diffuse reflector that is placed at the position where the measurement light specularly reflected by the surface of the workpiece is incident, and the focus position of the objective lens based on the measurement result of the displacement sensor A focus adjustment unit that adjusts the measurement light when the measurement light is regularly reflected on the surface of the workpiece, and after the measurement light that is regularly reflected on the surface of the workpiece is diffusely reflected by the diffuse reflector, The position of the focal point of the objective lens is adjusted based on the first measurement result measured by the displacement sensor using the first reflected light reflected from the surface.

  In the laser processing apparatus according to the first aspect of the present invention, when the measurement light is regularly reflected on the surface of the workpiece, the measurement light that is regularly reflected on the surface of the workpiece is diffusely reflected by the diffuse reflector, Based on the first measurement result measured by the displacement sensor using the first reflected light reflected from the surface, the position of the focal point of the objective lens is adjusted.

  Therefore, even when the surface (processed surface) of the workpiece is a regular reflection surface, the position of the focal point of the objective lens can be adjusted based on the measurement result measured by the displacement sensor using diffuse reflection light. As a result, it is possible to perform autofocus without switching the measurement method of the displacement sensor or exchanging the displacement sensor, regardless of the state of reflection on the surface (work surface) of the workpiece.

  This diffuse reflector is made of, for example, a surface of a metal block that has been subjected to satin plating or sandblasting, or a ceramic block. The shape of the diffuse reflector is arbitrary such as a plate shape or a spherical shape. This focus adjustment unit is configured by, for example, an error amplifier, a motor driver, and the like.

  When the measurement light is diffusely reflected on the surface of the workpiece, the focus adjustment unit is configured to use the second reflected light diffusely reflected on the surface of the workpiece based on the second measurement result measured by the displacement sensor. The focus position of the objective lens can be adjusted.

  Thereby, regardless of the reflection state of the surface (work surface) of the workpiece, autofocus can be performed without switching the measurement method of the displacement sensor or replacing the displacement sensor.

  The focus adjustment unit can select whether to adjust the position of the focal point of the objective lens with respect to either the regular reflection surface or the diffuse reflection surface based on the state of reflection on the surface of the workpiece.

  Accordingly, it is possible to appropriately perform autofocus based on the state of reflection on the surface (processed surface) of the workpiece.

  The focus adjustment unit can switch whether the focus position of the objective lens is adjusted with respect to either the regular reflection surface or the diffuse reflection surface when the measurement result of the displacement sensor is out of a predetermined range.

  As a result, the focal position adjustment method can be automatically switched according to the state of reflection on the surface (machined surface) of the workpiece.

  In this focus adjustment device, two or more pairs of displacement sensors and diffuse reflectors can be provided, and the diffuse reflector can be provided between the same pair of displacement sensors and objective lens and in the vicinity of the objective lens. .

  Thereby, the distance between a displacement sensor and a diffuse reflector can be shortened.

  In this focus adjustment apparatus, an objective lens is disposed between the first displacement sensor and the second displacement sensor, and the relative directions between the first displacement sensor and the second displacement sensor are orthogonal to each other. It can be set obliquely with respect to the first processing direction and the second processing direction.

  Thus, using two pairs of displacement sensors and diffuse reflectors, for example, pre-reading the displacement of the workpiece surface (machined surface) in the four machining directions of X + direction, X- direction, Y + direction, and Y- direction. It can be performed.

  In this focus adjustment apparatus, the first relative direction of the first displacement sensor with respect to the objective lens is set to a predetermined first processing direction, and the second relative direction of the second displacement sensor with respect to the objective lens is set to The second machining direction can be set perpendicular to the first machining direction.

  Thereby, the displacement of the surface (working surface) of the workpiece with respect to, for example, four machining directions of the workpiece in the X + direction, the X− direction, the Y + direction, and the Y− direction using the two sets of displacement sensors and the diffuse reflector. Can be measured.

  In this focus adjustment apparatus, at least four pairs of displacement sensors and diffuse reflectors are provided, and between the first displacement sensor and the second displacement sensor and between the third displacement sensor and the fourth displacement sensor. The objective lens can be disposed at the right and the relative direction between the first displacement sensor and the second displacement sensor can be orthogonal to the relative direction between the third displacement sensor and the fourth displacement sensor.

  Thereby, for example, the pre-reading of the displacement of the surface (working surface) of the workpiece can be performed more accurately in the four machining directions of the X + direction, the X− direction, the Y + direction, and the Y− direction.

  Each diffuse reflector can be provided on a member mounted around the objective lens.

  Thereby, a focus adjustment apparatus can be reduced in size simply.

  The measurement point of the displacement sensor can be set in front of the focal position of the objective lens in the workpiece processing direction.

  Thereby, the prefetch of the displacement of the surface (working surface) of a workpiece | work can be performed.

  In this focus adjustment apparatus, a displacement mechanism, a diffuse reflector, and an objective lens are connected, and a displacement mechanism that moves the displacement sensor, the diffuse reflector, and the objective lens as a unit in a direction perpendicular to the workpiece is further provided. Can be provided.

  This can reduce the error in the focal position of the objective lens and simplify the focus adjustment method.

  This moving mechanism is composed of, for example, a motor, a galvanometer, a screw, and the like.

  The focus adjustment device further includes a movement amount detection unit that detects a movement amount of the objective lens in a direction perpendicular to the workpiece, and the focus adjustment unit has an objective based on the detection result of the movement amount detection unit. The position of the focal point of the lens can be adjusted.

  Thereby, the error of the focus position of the objective lens can be reduced.

  The movement amount detection unit is configured by, for example, a rotary encoder, a linear encoder, an electrostatic capacitor type sensor, or the like.

  In this focus adjustment apparatus, the objective lens is constituted by a plurality of lenses, and the focus adjustment unit adjusts the position of the focus of the objective lens by adjusting the interval between the lenses of the objective lens. Can be. Note that the objective lens has a fixed focus, and may be realized by combining a lens that adjusts another focus.

  Thereby, the position of the focal point can be adjusted without moving the objective lens.

  In this focus adjustment apparatus, a displacement mechanism and a diffuse reflector can be connected, and a moving mechanism that moves the displacement sensor and the diffuse reflector integrally with respect to the workpiece can be further provided.

  Thereby, the distance between the measurement point of the workpiece displacement and the laser processing point can be adjusted.

  This moving mechanism is comprised by various actuators, for example.

  In this focus adjustment apparatus, the relative direction between the displacement sensor and the diffuse reflector can be set obliquely with respect to the first processing direction and the second processing direction that are orthogonal to each other.

  Thus, by using a pair of displacement sensors and a diffuse reflector, for example, the look-ahead of the displacement of the workpiece surface (machined surface) in the four machining directions of X + direction, X- direction, Y + direction, and Y- direction. It can be performed.

  In this focus adjustment apparatus, at least two sets in which the displacement sensor and the diffuse reflector are connected are provided, and the relative direction between the first set of the displacement sensor and the diffuse reflector is defined as a predetermined first processing direction. And the relative direction between the second set of displacement sensors and the diffuse reflector can be set to a second processing direction orthogonal to the first processing direction.

  Thereby, for example, the pre-reading of the displacement of the surface (working surface) of the workpiece can be performed more accurately with respect to the four processing directions of the X + direction, the X− direction, the Y + direction, and the Y− direction.

  In this focus adjustment apparatus, a displacement sensor and a diffuse reflector can be connected, and a rotation mechanism can be further provided that rotates the displacement sensor and the diffuse reflector integrally with respect to the workpiece around the objective lens.

  Thereby, it is possible to arbitrarily set the direction in which the pre-reading of the displacement of the workpiece surface (working surface) is performed.

  This rotation mechanism is constituted by, for example, a motor, a rotation gear, and the like.

  In this focus adjustment apparatus, a displacement mechanism that moves the displacement sensor and the diffuse reflector integrally with respect to the workpiece can be further provided.

  Thereby, the direction in which the pre-reading of the displacement of the surface (working surface) of the workpiece can be arbitrarily set, and the distance between the measurement point of the workpiece displacement and the laser machining point can be adjusted.

  This moving mechanism is comprised by various actuators, for example.

  In the laser processing apparatus according to the second aspect of the present invention, the above-described focus adjusting apparatus can be provided.

  Therefore, regardless of the reflection state of the workpiece surface (processed surface), autofocus can be performed without switching the measurement method of the displacement sensor or replacing the displacement sensor.

  According to the first aspect or the second aspect of the present invention, autofocus is performed without switching the measurement method of the displacement sensor or exchanging the displacement sensor regardless of the state of reflection of the work surface of the workpiece. be able to.

It is a block diagram which shows one Embodiment of the laser processing apparatus to which this invention is applied. It is the figure which showed typically the structural example of the thin film solar cell panel which is an example of a workpiece | work. It is a block diagram which shows the structural example of the focus adjustment apparatus mounted in a laser processing apparatus. It is a figure for demonstrating the focus adjustment method in case the process surface of a workpiece | work is a diffuse reflection surface. It is a figure for demonstrating the focus adjustment method in case the process surface of a workpiece | work is a diffuse reflection surface. It is a figure for demonstrating the focus adjustment method in case the process surface of a workpiece | work is a regular reflection surface. It is a figure for demonstrating the focus adjustment method in case the process surface of a workpiece | work is a regular reflection surface. It is a block diagram which shows the 1st modification of the focus adjustment apparatus mounted in a laser processing apparatus. It is a block diagram which shows the 2nd modification of the focus adjustment apparatus mounted in a laser processing apparatus. It is a figure which shows an example in case a diffuse reflection surface and a regular reflection surface are mixed. It is a figure for demonstrating the method to detect the state of reflection of the processed surface of a workpiece | work. It is a figure for demonstrating the method to detect the state of reflection of the processed surface of a workpiece | work. It is a figure which shows 1st Embodiment of the installation method of a displacement sensor and a diffuse reflection board. It is a figure which shows 1st Embodiment of the installation method of a displacement sensor and a diffuse reflection board. It is a figure which shows the modification of 1st Embodiment of the installation method of a displacement sensor and a diffused reflection board. It is a block diagram which shows the structural example of a process unit. It is a figure which shows 2nd Embodiment of the installation method of a displacement sensor and a diffuse reflection board. It is a figure which shows the 1st modification of 2nd Embodiment of the installation method of a displacement sensor and a diffused reflection board. It is a figure which shows the 2nd modification of 2nd Embodiment of the installation method of a displacement sensor and a diffused reflection board. It is a figure which shows the 3rd modification of 2nd Embodiment of the installation method of a displacement sensor and a diffused reflection board. It is a figure which shows the 4th modification of 2nd Embodiment of the installation method of a displacement sensor and a diffused reflection board. It is a figure for demonstrating the modification of the adjustment method of a focus position. It is a figure for demonstrating the modification of the adjustment method of a focus position. It is a figure for demonstrating the modification of the adjustment method of a focus position.

Hereinafter, modes for carrying out the present invention (hereinafter referred to as embodiments) will be described. The description will be given in the following order.
1. Embodiment 2 of laser processing apparatus 2. Example of installation method of displacement sensor and diffuse reflector Modified example

<1. Embodiment of Laser Processing Apparatus>
[Configuration Example of Laser Processing Apparatus 101]
FIG. 1 is an external view schematically showing an embodiment of a laser processing apparatus 101 to which the present invention is applied.

  Hereinafter, the side that is visible on the left side of FIG. 1 in the longitudinal direction of the laser processing apparatus 101 is the front side, and the opposite side is the rear side. Hereinafter, in the short direction of the laser processing apparatus 101, the side that is visible in the foreground in FIG. 1 is the right side, and the opposite side is the left side.

  Further, hereinafter, the horizontal direction (left-right direction) of the laser processing apparatus 101 is referred to as an X direction, and a direction from left to right is a positive direction. Hereinafter, the positive direction in the X direction is referred to as the X + direction, and the negative direction is referred to as the X− direction. Further, hereinafter, the depth direction of the laser processing apparatus 101 is referred to as a Y direction, and the direction from the front to the back is a positive direction. Hereinafter, the positive direction in the Y direction is referred to as the Y + direction, and the negative direction is referred to as the Y− direction. Furthermore, hereinafter, the vertical direction of the laser processing apparatus 101 is referred to as the Z direction, and the direction from the bottom to the top is defined as the positive direction. Hereinafter, the positive direction in the Z direction is referred to as the Z + direction, and the negative direction is referred to as the Z− direction. The X direction, the Y direction, and the Z direction are orthogonal to each other.

  The laser processing apparatus 101 is an apparatus that performs various types of processing on the workpiece 102 using laser light. The laser processing apparatus 101 is configured to include a gantry 111, a Y-axis drive unit 112, a mounting table 113, a gantry 114, and processing heads 115a to 115f.

  The Y-axis drive unit 112 is provided on the gantry 111 so as to extend in the Y direction, and moves the stage 113 on which the workpiece 102 is placed in the Y direction. Then, when the stage 113 moves in the Y direction, the processing position of the workpiece 102 by the laser light advances in the Y direction. In other words, the processing direction of the workpiece 102 is the Y direction.

  A gate-shaped gantry 114 is provided at a position slightly behind the center of the gantry 111 in the Y direction so as to cross the top of the gantry 111 in the X direction. Further, processing heads 115a to 115f are provided on the front surface of the beam of the gantry 114.

  The processing heads 115a to 115f each process the workpiece 102 by irradiating the workpiece 102 with laser light. The machining heads 115a to 115f can be moved in the X direction along the beam of the gantry 114 by a drive system (not shown). Then, when the machining heads 115a to 115f move in the X direction, the machining position of the workpiece 102 by the laser light advances in the X direction. In other words, the machining direction of the workpiece 102 is the X direction.

  The machining heads 115a to 115f can be moved in the Z direction by a drive system (not shown).

  Hereinafter, when it is not necessary to individually distinguish the processing heads 115a to 115f, they are simply referred to as the processing heads 115. Moreover, the number of the processing heads shown in FIG. 1 is an example, and can be set to an arbitrary number.

[Configuration example of work 102]
The type of the workpiece 102 is not particularly limited, but an example is shown in FIG. Specifically, FIG. 2 schematically shows a configuration example of a thin-film solar cell panel 151 using CIGS (Copper Indium Gallium DiSelenide).

  The thin-film solar battery panel 151 has a four-layer structure of a glass substrate 151A, a back electrode layer 151B, a power generation layer 151C, and a transparent electrode layer 151D. For example, the thin film solar cell panel 151 is processed by irradiating laser light from the transparent electrode layer 151D side. The back electrode layer 151B is a metal layer made of, for example, Mo, and regularly reflects laser light. The power generation layer 151C is constituted by, for example, a light absorption layer made of CIGS or the like and a buffer layer made of ZnS, InS, or the like, and diffusely reflects the laser light. The transparent electrode layer 151D is made of, for example, ZnO and diffuses and reflects the laser light.

  Therefore, in the conventional displacement sensor, the displacement or distance with respect to the glass substrate 151A, the power generation layer 151C, and the transparent electrode layer 151D is measured using the diffuse reflection method, and the displacement or distance with respect to the back electrode layer 151B is measured with the regular reflection method. It is necessary to measure using

  In addition, the structure of the thin film solar cell panel used as the process symmetry of the laser processing apparatus 101 is not limited to this example. For example, a thin film solar cell panel or the like in which the back electrode layer 151B and the transparent electrode layer 151D are disposed in reverse and processed by irradiating laser light from the glass substrate 151A side is also envisaged.

[Configuration Example of Focus Adjustment Device 201]
FIG. 3 is a block diagram illustrating a configuration example of the focus adjustment apparatus 201 mounted on each processing head 115 of the laser processing apparatus 101.

  The focus adjustment device 201 includes a displacement sensor 211, a diffuse reflector 212, an error amplifier (EA) 213, a motor driver 214, a Z-axis drive motor 215, a Z-axis drive screw 216, and an objective lens 217. Is done.

  The displacement sensor 211 is a displacement sensor that measures the displacement of the object to be measured or the distance to the object to be measured using probe light (measurement light) that is laser light for measurement having a predetermined wavelength (for example, 650 nm). . The displacement sensor 211 includes a laser light source 231, a light receiving lens 232, a linear sensor 233, and a signal processing unit 234.

  The laser light source 231 emits probe light (measurement light) that is laser light for measurement having a predetermined wavelength (for example, 650 nm). The probe light emitted from the laser light source 231 is irradiated obliquely with respect to the processing surface, which is the surface of the workpiece 102, through a lens or the like (not shown) constituting a light projecting unit together with the laser light source 231.

  The incident angle θ of the probe light emitted from the laser light source 231 to the processed surface of the workpiece 102 is set within a range of 0 degree <θ <90 degrees.

  The light receiving lens 232 receives the reflected light of the probe light emitted from the laser light source 231 and forms an image of the received reflected light on the linear sensor 233.

  The linear sensor 233 is configured by, for example, a CCD image sensor or a CMOS image sensor in which light receiving elements are arranged one-dimensionally. Each light receiving element of the linear sensor 233 detects the amount of reflected light of the probe light incident through the light receiving lens 232. The linear sensor 233 supplies a detection signal indicating the amount of light received by each light receiving element to the signal processing unit 234.

  The signal processing unit 234 calculates the displacement of the object to be measured or the distance to the object to be measured based on the imaging position of the reflected light of the probe light at the linear sensor 233 (the position where the amount of received light reaches a peak) or the distribution of the amount of received light. To detect. Then, the signal processing unit 234 supplies a measurement signal indicating the detection result to the error amplifier 213. Hereinafter, a case where the signal processing unit 234 outputs a measurement signal indicating the distance to the object to be measured will be described.

  The diffuse reflection plate 212 is installed at a position where the specularly reflected probe light is incident when the probe light emitted from the laser light source 231 is specularly reflected on the processed surface of the workpiece 102. The diffuse reflection plate 212 diffusely reflects the probe light incident through the processed surface of the workpiece 102.

  Note that the direction of the diffusive reflecting plate 212 may be a direction in which the probe light specularly reflected by the processed surface of the workpiece 102 is surely incident. For example, the probe light specularly reflected by the processed surface of the workpiece 102 is vertical. The incident direction is set.

  The diffuse reflector 212 is not particularly limited as long as it is not specularly reflected. For example, the diffused reflector 212 is made of a metal block having a satin-plated or sandblasted surface, or a ceramic block. . However, a material having a high reflectivity with respect to the wavelength of the probe light so that more probe light diffusely reflected by the diffuse reflector 212 is incident on the light receiving lens 232 of the displacement sensor 211 and the light receiving sensitivity of the displacement sensor 211 is increased. Alternatively, it is desirable to use a coating for the diffuse reflector 212.

  A focus setting value indicating the target value of the measurement signal output from the displacement sensor 211 is input to the error amplifier 213. For example, the focus setting value is set to a value of a measurement signal output from the displacement sensor 211 when the focus position of the objective lens 217 is aligned with the processing surface of the workpiece 102. Then, an error signal obtained by amplifying the difference between the value of the measurement signal supplied from the displacement sensor 211 and the focus setting value is supplied to the error amplifier 213 to the motor driver 214. Accordingly, the error signal is a value reflecting a deviation (error) between the focal position of the objective lens 217 and the processing surface of the workpiece 102.

  The motor driver 214 eliminates the error indicated by the error signal and drives the Z-axis driving motor 215 so that the focal point of the objective lens 217 is aligned with the processing surface of the workpiece 102 to move the objective lens 217 in the Z direction. As a result, the position of the focal point of the objective lens 217 is adjusted.

  The Z-axis drive motor 215 is connected to the objective lens 217 via a Z-axis drive screw 216. Then, the movement in the rotational direction of the Z-axis drive motor 215 is transmitted to the objective lens 217 via the Z-axis drive screw 216, so that the direction perpendicular to the machining surface of the workpiece 102 indicated by the arrow A is obtained. The objective lens 217 moves in the (Z direction). Thereby, the focal position of the objective lens 217 moves in the Z direction.

  The objective lens 217 receives the processing laser beam LB and forms an image on the processing surface of the workpiece 102.

[Focus Adjustment Method of Focus Adjustment Device 201]
Next, a focus adjustment method of the focus adjustment apparatus 201 will be described with reference to FIGS.

(Focus adjustment method for diffuse reflection surface)
First, with reference to FIG. 4 and FIG. 5, the focus adjustment method when the processed surface of the workpiece 102 is a diffuse reflection surface will be described.

  When the processing surface of the workpiece 102 is a diffuse reflection surface, the probe light emitted from the laser light source 231 proceeds in the direction of arrow A and is diffusely reflected on the processing surface of the workpiece 102. Part of the diffusely reflected probe light is reflected in the direction of the displacement sensor 211 as indicated by arrows B1 to B4. Among these, as indicated by arrows B <b> 2 and B <b> 3, the reflected light incident on the light receiving lens 232 forms an image on the linear sensor 233.

  On the other hand, a part of the probe light diffusely reflected on the processed surface of the workpiece 102 is reflected in the direction of the diffuse reflector 212 and further diffusely reflected by the diffuse reflector 212 as indicated by arrows B5 to B7. Since the reflected light diffusely reflected by the diffuse reflection plate 212 is very weak due to being diffusely reflected twice, it is again diffusely reflected by the processed surface of the workpiece 102 and enters the light receiving lens 232 of the displacement sensor 211. There is hardly anything.

  Accordingly, the displacement sensor 211 performs measurement using the reflected light that is diffusely reflected on the processed surface of the workpiece 102 for the first time, as in the case of the normal diffuse reflection method.

  FIG. 5 schematically shows the positional relationship between the displacement sensor 211, the diffuse reflector 212, and the objective lens 217.

  Here, in a state where the objective lens 217 is focused on the processing surface of the workpiece 102 (hereinafter referred to as a focused state), the height from the processing surface of the workpiece 102 to the displacement sensor 211 (probe light emission port) is high. The distance (work distance) between the objective lens 217 and the work surface of the workpiece 102 is WD, and the distance until the probe light emitted from the displacement sensor 211 enters the work surface of the work 102 is d1. . Further, the incident angle of the probe light emitted from the displacement sensor 211 to the processed surface of the workpiece 102 is θ. At this time, the following expression (1) holds.

  h1 = d1 × cosθ (1)

  The distance d1 is expressed by the following equation (2) from the equation (1).

  d1 = h1 / cosθ (2)

  At this time, since the displacement sensor 211 performs measurement with the reflected light diffusely reflected by the processed surface of the workpiece 102, the measurement distance of the displacement sensor 211 is the distance d1. Accordingly, the displacement sensor 211 supplies a measurement signal indicating the distance d1 as a measurement result to the error amplifier 213.

  On the other hand, the error amplifier 213 receives the value of the measurement signal indicating the distance d1 in the focused state at this time as the focus setting value. More simply, the focus setting value is set to the distance d1. Therefore, the value of the error signal output from the error amplifier 213 is 0.

  Further, when the workpiece 102 moves in the Z-direction (downward) from the in-focus state by the distance δ, the distance d1 ′ until the probe light is incident on the processing surface of the workpiece 102 is expressed by the following equation (3). Is done.

  d1 '= (h1 + δ) / cosθ (3)

  Therefore, the difference between the distance d1 before the workpiece 102 moves and the distance d1 'after the workpiece 102 is represented by the following equation (4).

  d1′−d1 = δ / cosθ (4)

  At this time, the displacement sensor 211 supplies a measurement signal indicating the distance d <b> 1 ′ as a measurement result to the error amplifier 213. Therefore, the value of the error signal output from the error amplifier 213 is a value indicating δ / cos θ on the right side of Equation (4).

  Here, since the incident angle θ is a design value and known, the motor driver 214 can determine the displacement δ in the Z direction of the machining surface of the workpiece 102 based on the value of the error signal. The motor driver 214 can focus the objective lens 217 on the processing surface of the workpiece 102 by driving the Z-axis driving motor 215 and moving the objective lens 217 downward by a distance δ.

(Focus adjustment method for regular reflection surface)
Next, with reference to FIG. 6 and FIG. 7, the focus adjustment method when the processed surface of the workpiece 102 is a regular reflection surface will be described.

  When the processed surface of the workpiece 102 is a regular reflection surface, the probe light emitted from the laser light source 231 proceeds in the direction of arrow A, is regularly reflected on the processed surface of the workpiece 102, and proceeds in the direction of arrow B. The probe light traveling in the direction of arrow B is incident on the diffuse reflector 212 and diffusely reflected by the diffuse reflector 212.

  Of the probe light diffusely reflected by the diffuse reflector 212, the probe light that has traveled in the directions of the arrows C1 and C2 is specularly reflected again on the processed surface of the workpiece 102, travels in the directions of the arrows D1 and D2, Incident. In this way, a part of the probe light diffusely reflected by the diffuse reflection plate 212 enters the light receiving lens 232 and forms an image on the linear sensor 233. The displacement sensor 211 performs measurement using a part of the reflected light that is diffusely reflected by the diffuse reflector 212 and then regularly reflected by the processed surface of the workpiece 102.

  FIG. 7 schematically shows the positional relationship between the displacement sensor 211, the diffuse reflector 212, and the objective lens 217, as in FIG. 5.

  Here, in the in-focus state, the distance until the probe light specularly reflected by the processed surface of the workpiece 102 enters the diffuse reflector 212 is d2. In addition, the height from the processing surface of the workpiece 102 to the incident position of the probe light on the diffuse reflection plate 212 is h2.

  Here, since the reflection angle of the probe light regularly reflected by the processed surface of the workpiece 102 is equal to the incident angle θ, the following equation (5) is established.

  h2 = d2 × cosθ (5)

  Therefore, the distance until the probe light emitted from the displacement sensor 211 enters the diffuse reflector 212 via the processed surface of the workpiece 102 is expressed by the following equation (6).

  d1 + d2 = (h1 + h2) / cosθ (6)

  At this time, since the displacement sensor 211 performs the measurement using the reflected light that is diffusely reflected by the diffuse reflection plate 212 and then regularly reflected by the processed surface of the workpiece 102, the measurement distance of the displacement sensor 211 is the distance d1 + d2. Therefore, the displacement sensor 211 supplies a measurement signal indicating the distance d1 + d2 to the error amplifier 213 as a measurement result.

  On the other hand, the error amplifier 213 receives the value of the measurement signal indicating the distance d1 + d2 in the focused state at this time as the focus setting value. More simply, the focus setting value is set to the distance d1 + d2. Therefore, the value of the error signal output from the error amplifier 213 is 0.

  Similarly to the example of FIG. 5 described above, when the work 102 moves from the in-focus state by a distance δ in the Z-direction (downward), the probe light passes through the processed surface of the work 102 and the diffuse reflector 212. The distance d 1 ′ + d 2 ′ until the light enters is expressed by the following equation (7).

  d1 '+ d2' = (h1 + h2 + 2δ) / cosθ (7)

  Therefore, the difference between the distance d1 + d2 before the workpiece 102 moves and the distance d1 '+ d2' after the workpiece 102 is expressed by the following equation (8).

  d1 ′ + d2 ′ − (d1 + d2) = 2δ / cosθ (8)

  At this time, the displacement sensor 211 supplies a measurement signal indicating the distance d1 ′ + d2 ′ to the error amplifier 213 as a measurement result. Therefore, the value of the error signal output from the error amplifier 213 is a value indicating 2δ / cos θ on the right side of Equation (8).

  Here, since the incident angle θ is a design value and known, the motor driver 214 can determine the displacement δ in the Z direction of the machining surface of the workpiece 102 based on the value of the error signal. The motor driver 214 can focus the objective lens 217 on the processing surface of the workpiece 102 by driving the Z-axis driving motor 215 and moving the objective lens 217 downward by a distance δ.

  Then, the focus adjustment device 201 is directed to either the regular reflection surface or the diffuse reflection surface based on the state of reflection of the processed surface of the workpiece 102 by an external command or setting, or automatically as described later. To select whether to adjust the focus of the objective lens 217. In other words, the focus adjustment device 201 selects either the focus adjustment method for the regular reflection surface or the focus adjustment method for the diffuse reflection surface based on the reflection state of the processed surface of the workpiece 102, and the focus of the objective lens 217. Adjust the position.

  In this way, regardless of whether the processed surface of the workpiece 102 is a regular reflection surface or a diffuse reflection surface, autofocus can be performed without switching the measurement method of the displacement sensor 211 or replacing the displacement sensor 211. . Also, various adjustments and settings required when switching the measurement method of the displacement sensor 211 or exchanging the displacement sensor 211 become unnecessary.

  In FIG. 7, the distance δ is shown to be large for easy understanding of the drawing, and the incident position of the probe light on the diffusing reflection plate 212 is greatly shifted before and after the workpiece 102 moves. . However, in practice, the displacement δ is a very small value, and the change in the incident position of the probe light on the diffuse reflector 212 before and after the workpiece 102 moves is very small.

  Further, when the workpiece 102 is tilted, the incident angle θ and the reflection angle θ change, and the incident position of the probe light on the diffuse reflector 212 changes. However, the change in the tilt of the workpiece 102 is very small, and the change in the incident position of the probe light on the diffuse reflector 212 before and after the workpiece 102 is tilted is very small.

  Further, in the displacement sensor 211, measurement is performed based on the distribution of the received light amount of the reflected light that has been diffusely reflected in all directions by the diffuse reflection plate 212 and then reflected by the processing surface of the workpiece 102 and returned to the displacement sensor 211. Therefore, the influence of the change in the incident position of the probe light on the diffuse reflection plate 212 on the measurement result of the displacement sensor 211 is very small and can be ignored.

  Since the incident angle θ is a fixed value, cos θ is a constant. Therefore, for example, the displacement sensor 211 may output a value obtained by multiplying the measurement result by the constant cos θ. Thereby, when the processing surface of the workpiece 102 is a diffuse reflection surface, a measurement signal indicating the height h1 or the height h1 + δ is output from the displacement sensor 211, and an error signal indicating the displacement δ is output from the error amplifier 213. become. When the processing surface of the workpiece 102 is a regular reflection surface, a measurement signal indicating the height h1 + h2 or the height h1 + h2 + 2δ is output from the displacement sensor 211, and an error signal indicating the displacement δ × 2 is output from the error amplifier 213. It becomes like this.

  For example, the error amplifier 213 may output a value obtained by multiplying the difference between the focus setting value and the measurement signal value by a constant cos θ. As a result, when the processed surface of the workpiece 102 is a diffuse reflection surface, an error signal indicating the displacement δ is output from the error amplifier 213. When the processed surface of the workpiece 102 is a regular reflection surface, an error signal indicating the displacement δ × 2 is output from the error amplifier 213.

  Hereinafter, the displacement in the Z direction of the processed surface of the workpiece 102 is also simply referred to as the displacement of the workpiece 102.

[First Modification of Focus Adjustment Device]
For example, if the Z-axis drive motor 215 is operated at a high speed in order to increase the autofocus response speed, the load on the Z-axis drive motor 215 at the start of operation becomes heavy. 215 step-out may occur. For example, when the Z-axis drive motor 215 is configured by a pulse motor and performs open loop control, if the Z-axis drive motor 215 is stepped out, the Z-direction of the objective lens 217 recognized by the motor driver 214 is detected. There is a deviation between the position and the actual position. This deviation is accumulated every time auto-focusing is performed. Finally, the focal point of the objective lens 217 is not aligned with the processing surface of the workpiece 102, so that the processing quality may be deteriorated.

  In order to prevent this phenomenon, for example, it may be possible to periodically perform an initialization operation for resetting the accumulated error. However, such an initialization operation is troublesome for the user. Further, when the laser processing apparatus 101 is continuously operated, the initialization operation cannot be performed.

  The focus adjusting device 301 in FIG. 8 is intended to prevent such a phenomenon from occurring.

  The focus adjustment device 301 is different from the focus adjustment device 201 of FIG. 3 in that a connection member 311 is added.

  The displacement sensor 211, the diffuse reflector 212, and the objective lens 217 are connected via a connection member 311. The connection member 311 is connected to the Z-axis drive motor 215 via the Z-axis drive screw 216. Then, the movement in the rotation direction of the Z-axis drive motor 215 is transmitted to the connection member 311 via the Z-axis drive screw 216, so that the direction perpendicular to the machining surface of the workpiece 102 indicated by the arrow A is obtained. The connecting member 311 moves in the (Z direction). As a result, the displacement sensor 211, the diffuse reflector 212, and the objective lens 217 connected to the connection member 311 move in the Z direction as a unit.

  As a result, the measurement signal of the displacement sensor 211 regardless of whether or not the Z-axis driving motor 215 has stepped out and whether the processed surface of the workpiece 102 is a diffuse reflection surface or a regular reflection surface. The focal point of the objective lens 217 is adjusted by simply adjusting the position of the connecting member 311 in the Z direction so that the value of the error signal output from the error amplifier 213 becomes zero. Can be matched to the machined surface.

  Therefore, even if the Z-axis driving motor 215 is stepped out, the objective lens 217 can be accurately focused on the processing surface of the workpiece 102.

  Further, it is not necessary to change the control method of the motor driver 214 depending on the state of reflection of the processed surface of the workpiece 102. That is, depending on whether the processed surface of the workpiece 102 is a diffuse reflection surface or a regular reflection surface, the value of the error signal is either δ / cos θ in the above equation (4) or 2δ / cos θ in the equation (8). The driver 214 may adjust the position of the objective lens 217 in the Z direction so that the value of the error signal becomes 0 regardless of the fluctuation of the value.

[Second Modification of Focus Adjustment Device]
The focus adjustment device 351 in FIG. 9 is provided with a countermeasure against the step-out of the Z-axis drive motor 215, similarly to the focus adjustment device 301 in FIG. 8.

  Compared with the focus adjustment device 301 in FIG. 8, the focus adjustment device 351 includes a mount 361 instead of the connection member 311, a motor driver 362 instead of the motor driver 214, and a rotary encoder 363. Is different.

  In the focus adjustment device 351, the displacement sensor 211 and the diffuse reflector 212 are fixed to the mount 361, and only the objective lens 217 moves in the Z direction during autofocus.

  The motor driver 362 detects the amount of movement of the objective lens 217 in the Z direction based on the number of rotations of the Z-axis drive motor 215 counted by the rotary encoder 363, and detects the position of the objective lens 217 in the Z direction. . Therefore, the motor driver 362 accurately detects the position of the objective lens 217 in the Z direction based on the actual number of rotations of the Z-axis driving motor 215 even if the Z-axis driving motor 215 is stepped out. be able to.

  Thus, even if the Z-axis driving motor 215 is stepped out and the objective lens 217 cannot be moved to the target position, the error can be detected and corrected at the next autofocus. Therefore, accumulation of displacement of the position of the objective lens 217 in the Z direction is prevented.

  When the Z-axis drive motor 215 is configured by a linear motor, for example, a linear encoder is provided instead of the rotary encoder 363.

  Further, in order to drive the objective lens 217 at a high speed, when the Z-axis drive motor 215 is configured by a voice coil motor or the like, for example, a linear encoder or an electrostatic capacitor type sensor is used instead of the rotary encoder 363. The position of the objective lens 217 is detected.

  Further, when the objective lens 217 is driven in the Z direction using a galvanometer capable of operating at high speed, the position of the objective lens 217 is detected using a digital galvanometer with an encoder instead of the rotary encoder 363, for example.

  Since the focus adjustment device 351 moves only the objective lens 217 in the Z direction as compared with the focus adjustment device 301 in FIG. 8, it is possible to reduce the load on the drive mechanism in the Z direction for autofocus. Therefore, the response speed of the drive mechanism can be increased, and the autofocus reaction speed can be increased. Alternatively, the drive mechanism can be downsized, and the laser processing apparatus 101 can be downsized and reduced in cost.

[Focus adjustment method when diffuse reflection surface and regular reflection surface coexist]
Next, with reference to FIG. 10 to FIG. 12, a focus adjustment method when a diffuse reflection surface and a regular reflection surface are mixed will be described.

  In FIG. 10, as an example in the case where a diffuse reflection surface and a regular reflection surface are mixed, the workpiece 102 is configured by a thin film solar cell panel 401 using CIGS, and the thin film solar cell panel 401 is placed on the substrate holder 402. The case where it processes is shown. 10 is a schematic view of the thin film solar cell panel 401 placed on the substrate holder 402 as viewed from above, and the lower diagram is a thin film solar cell panel placed on the substrate holder 402. It is a figure which shows the cross section of 401 typically.

  In this example, the thin-film solar cell panel 401 is in a state before laser processing in the P1 step, and a back electrode layer 401B that is a metal layer made of Mo or the like is laminated on a glass substrate 401A. As described above, the back electrode layer 401B regularly reflects the laser light.

  On the other hand, the substrate holder 402 is made of black anodized aluminum and diffusely reflects laser light.

  Hereinafter, in order to make the description easy to understand, it is assumed that the surface of the back electrode layer 401B of the thin-film solar cell panel 401 and the surface of the substrate holder 402 have the same height.

  For example, when processing the back electrode layer 401B of the thin-film solar battery panel 401 while moving the processing head 115 in the direction of arrow A, when the processing head 115 comes on the substrate holder 402, the surface of the substrate holder 402 is Auto focus is performed. Thereafter, when the processing head 115 comes on the thin film solar cell panel 401, autofocus is performed on the surface of the back electrode layer 401B of the thin film solar cell panel 401.

  Here, when processing the back electrode layer 401B, since the back electrode layer 401B is a regular reflection surface, the focus setting value input to the error amplifier 213 is the distance d1 + d2 as described above with reference to FIG. Set to

  On the other hand, when auto-focusing is performed on the surface of the substrate holder 402, the surface of the substrate holder 402 is a diffuse reflection surface. Therefore, even if the focus of the objective lens 217 is on the surface of the substrate holder 402, the displacement sensor 211 Is a distance d1, which is shorter than the focus setting value by a distance d2.

  Accordingly, when the displacement sensor 211, the diffuse reflector 212, and the objective lens 217 are moved together in the Z direction as in the focus adjustment device 301 of FIG. 8, the measurement distance of the displacement sensor 211 is d1 + d2. Since it is controlled, the objective lens 217 moves by a distance d2 × cos θ in the Z + direction.

  In addition, when only the objective lens 217 is moved in the Z direction as in the focus adjustment device 351 in FIG. 9, the objective lens 217 is moved in the Z + direction by a distance d2 × cos θ / 2.

  Here, in general, the distance d2 from when the probe light is specularly reflected by the processed surface of the workpiece 102 to when it enters the diffuse reflector 212 is much larger than the displacement of the workpiece 102 in the Z direction. Therefore, in any of the above cases, the moving distance of the objective lens 217 on the substrate holder 402 is larger than that during normal autofocus.

  Therefore, after that, when autofocusing is performed on the surface of the back electrode layer 401B of the thin film solar cell panel 401, the moving distance of the objective lens 217 becomes long and the reaction speed of autofocus becomes slow.

  Incidentally, some commercially available displacement sensors have a function of setting a length measurement range and outputting an error signal when the length measurement range is exceeded. Accordingly, the length measurement range of the displacement sensor 211 is set to the focus setting value ± α, and when the error signal indicating that the length measurement distance exceeds the length measurement range is output from the displacement sensor 211, the auto focus is stopped. Then, it is conceivable that the movement of the objective lens 217 in the Z direction is stopped or returned to the position before the movement.

  Note that α is set to a value larger than the assumed range of displacement in the Z direction of the thin-film solar cell panel 401 and smaller than the distance d2.

  Accordingly, in the example of FIG. 10, when the autofocus with respect to the surface of the substrate holder 402 is stopped halfway and the autofocus is performed with respect to the surface of the back electrode layer 401 </ b> B of the thin film solar cell panel 401, the objective lens 217 is moved. The distance becomes shorter and the autofocus response speed becomes faster.

  Here, the case where the substrate holder 402 is not the object to be processed and the state of reflection of the object to be processed is only one type of the diffuse reflection surface (the back electrode layer 401B of the thin film solar cell panel 401) has been described. On the other hand, it is also assumed that the state of reflection on the processed surface is changed from the diffuse reflection surface to the regular reflection surface or from the regular reflection surface to the diffuse reflection surface during the processing.

  In this case, for example, when an error signal indicating that the measurement distance is out of the measurement range is output from the displacement sensor 211, it can be determined that the state of reflection on the processed surface has changed. When it is determined that the state of reflection on the processed surface has changed, it is possible to switch whether the focus of the objective lens 217 is adjusted with respect to either the regular reflection surface or the diffuse reflection surface. That is, it is possible to switch from the focus adjustment method for the diffuse reflection surface to the focus adjustment method for the regular reflection surface, or from the focus adjustment method for the regular reflection surface to the focus adjustment method for the diffuse reflection surface.

  For example, when the displacement sensor 211, the diffuse reflector 212, and the objective lens 217 are moved together in the Z direction as in the focus adjustment device 301 in FIG. 8, the error amplifier 213 is moved according to the state of reflection on the processing surface. The focus setting value to be input to may be switched to a value for the diffuse reflection surface (distance d1) or a value for the regular reflection surface (distance d1 + d2).

  Further, when only the objective lens 217 is moved in the Z direction as in the focus adjustment device 351 in FIG. 9, for example, in addition to switching the focus setting value according to the state of reflection on the processing surface, the motor driver 214. The method for obtaining the displacement of the workpiece 102 may be switched. That is, when the processing surface is a diffuse reflection surface, the displacement δ is obtained based on the right side of the above-described equation (4), and when the processing surface is a regular reflection surface, the displacement is based on the right side of the above-described equation (8). What is necessary is just to obtain | require (delta).

  When the above-described length measurement range setting function is not mounted on the displacement sensor 211, for example, the reflection state of the processed surface of the workpiece 102 is detected based on the intensity of the probe light incident on the diffuse reflector. It may be.

  FIGS. 11 and 12 show a part of a configuration example of the focus adjustment device 451 configured to detect the reflection state of the processed surface of the workpiece 102 based on the intensity of the probe light incident on the diffuse reflector. . 11 shows a case where the processed surface of the workpiece 102 is a regular reflection surface, and FIG. 12 shows a case where the processed surface of the workpiece 102 is a diffuse reflection surface.

  The focus adjustment device 451 is different from the focus adjustment device 201 of FIG. 3 in that a diffuse reflection plate 461 is provided instead of the diffuse reflection plate 212, and a photo sensor 462 and an amplification comparator 463 are provided. .

  A pinhole 461A is provided at the center of the diffuse reflector 461. The diffuse reflection plate 461 is arranged such that when the probe light emitted from the laser light source 231 of the displacement sensor 211 is specularly reflected on the processing surface of the workpiece 102, a part of the specularly reflected probe light is incident on the pinhole 461A. The

  The photosensor 462 detects the amount of probe light passing through the pinhole 461A, and supplies a detection signal indicating the detection value to the amplification comparator 463. The amplification comparator 463 amplifies the detection signal from the photosensor 462 and then compares the value of the detection signal after amplification with a predetermined threshold value, so that the processed surface of the workpiece 102 is either a regular reflection surface or a diffuse reflection surface. It is determined whether it is.

  For example, when the processing surface of the workpiece 102 is a regular reflection surface, as shown in FIG. 11, the probe light emitted from the laser light source 231 and traveling in the direction of arrow A is regularly reflected by the processing surface of the workpiece 102. Most of the light travels in the direction of arrow B, and a part of the light enters the pinhole 461A of the diffuse reflector 461. Accordingly, the amount of probe light detected by the photosensor 462 increases.

  On the other hand, when the processing surface of the workpiece 102 is a diffuse reflection surface, as shown in FIG. 12, the probe light emitted from the laser light source 231 and traveling in the direction of arrow A is diffusely reflected by the processing surface of the workpiece 102. Only part of the light travels in the direction of arrow B, and further part of the light enters the pinhole 461A of the diffuse reflector 461. Accordingly, the amount of probe light detected by the photosensor 462 is reduced.

  Therefore, the amplification comparator 463 determines that the processed surface of the workpiece 102 is a regular reflection surface when the value of the detection signal after amplification is equal to or greater than a predetermined threshold value, and if the value of the workpiece 102 is less than the predetermined threshold value, It is determined that the processed surface is a diffuse reflection surface. Then, the amplification comparator 463 supplies a signal indicating the determination result to the displacement sensor 211, the motor driver 214, and the like.

  Thereby, the state of reflection of the processed surface of the workpiece 102 can be automatically detected, and based on the result, the focus adjustment method of the objective lens 217 can be automatically switched as described above.

<2. Example of installation method of displacement sensor and diffuse reflector>
Next, an example of a method for installing the displacement sensor 211 and the diffuse reflector 212 will be described.

  Hereinafter, unless otherwise specified, the processing direction of the laser processing apparatus 101 is assumed to be four directions of X +, X−, Y +, and Y−.

[First Embodiment of Installation Method of Displacement Sensor 211 and Diffuse Reflecting Plate 212]
First, a first embodiment of a method for installing the displacement sensor 211 and the diffuse reflector 212 will be described with reference to FIGS.

  The measurement point of the displacement sensor 211, that is, the position where the probe light emitted from the laser light source 231 is irradiated onto the machining surface of the workpiece 102 is the laser machining point, that is, the laser beam emitted from the objective lens 217 is It is desirable to be as close as possible to the position where the processing surface is irradiated. However, if the measurement point is too close to the laser processing point, the probe light receives disturbance due to the laser plasma generated during laser processing, and the measurement accuracy may be reduced. Therefore, it is desirable that the measurement point be separated from the laser processing point by a predetermined distance (for example, 5 to 10 mm) or more so as not to be disturbed by the laser plasma.

  At this time, by setting the measurement point at a position offset forward from the laser processing point in the processing direction, it is possible to pre-read the displacement of the workpiece 102 to be processed from now on and to perform autofocus based on the pre-read result. . Thereby, even if the response speed of the displacement sensor 211 or the control system is limited, the processing speed is increased, or the displacement of the workpiece 102 in the Z-axis direction is large, the focal position of the objective lens 217 is increased. Can follow the displacement of the workpiece 102 accurately.

  FIG. 13 and FIG. 14 show an example of an installation method of the displacement sensor 211 and the diffusing reflection plate 212 that can set the measurement point at a position offset in the processing direction from the laser processing point. FIG. 13 is a view of the positional relationship between the displacement sensor 211 and the diffuse reflection plate 212 as viewed from above, and FIG. 14 is a view of the positional relationship between the displacement sensor 211 and the diffuse reflection plate 212 as viewed from the side. In FIG. 13, the left to right direction is the X + direction, and the bottom to top direction is the Y + direction.

  In this example, four sets of the displacement sensor 211 and the diffuse reflector 212 are provided. In FIG. 14, the displacement sensor 211c is not shown for easy understanding of the drawing.

  Hereinafter, the displacement sensors 211a to 211d are simply referred to as the displacement sensor 211 when it is not necessary to individually distinguish them, and the diffuse reflectors 212a to 212d are simply referred to as the diffuse reflector 212 when it is not necessary to distinguish them individually. Further, hereinafter, when it is not necessary to individually distinguish the measurement points MPa to MPd, they are simply referred to as measurement points MP. The same applies to the other embodiments described below.

  The displacement sensor 211a and the displacement sensor 211b are provided at positions symmetrical with respect to the objective lens 217 in the X direction. In other words, the objective lens 217 is disposed between the displacement sensor 211a and the displacement sensor 211b, and the relative direction between the displacement sensor 211a and the displacement sensor 211b is set to the X direction. The relative direction of the displacement sensor 211a with respect to the objective lens 217 is set to the X-direction, and the relative direction of the displacement sensor 211b to the objective lens 217 is set to the X + direction.

  The displacement sensor 211c and the displacement sensor 211d are provided at positions symmetrical with respect to the objective lens 217 in the Y direction. In other words, the objective lens 217 is disposed between the displacement sensor 211c and the displacement sensor 211d, and the relative direction between the displacement sensor 211c and the displacement sensor 211d is set in the Y direction. The relative direction of the displacement sensor 211c with respect to the objective lens 217 is set to the Y-direction, and the relative direction of the displacement sensor 211d to the objective lens 217 is set to the Y + direction.

  A diffuse reflection block 501 is mounted below the objective lens 217. The diffuse reflection block 501 has a shape in which an octagonal cross section is provided with four rectangular surfaces at an interval of 90 degrees with one side of the octagon being the upper end and facing obliquely downward, with the lower surface being square. Have. In addition, diffuse reflectors 212a to 212d are provided on four rectangular surfaces, respectively.

  The diffuse reflection plate 212a is provided between the displacement sensor 211a and the objective lens 217 so as to face obliquely downward in the X-direction. The diffuse reflection plate 212b is provided between the displacement sensor 211b and the objective lens 217 so as to face obliquely downward in the X + direction. In addition, the diffuse reflector 212a and the diffuse reflector 212b are provided at positions that are symmetrical about the objective lens 217 in the X direction.

  The diffuse reflector 212c is provided between the displacement sensor 211c and the objective lens 217 so as to face obliquely downward in the Y-direction. The diffuse reflection plate 212d is provided between the displacement sensor 211d and the objective lens 217 so as to face obliquely downward in the Y + direction. Further, the diffuse reflection plate 212c and the diffuse reflection plate 212d are provided at positions symmetrical with respect to the objective lens 217 in the Y direction.

  For the diffuse reflectors 212a to 212d, for example, a ceramic plate having a high reflectivity with respect to the probe light may be attached to the diffuse reflector block 501, or the diffuse reflector block 501 is made of an aluminum material or the like. Alternatively, the diffuse reflection plates 212a to 212d may be formed on the surface of the diffuse reflection block 501 by sandblasting or anodizing.

  As indicated by an arrow Aa in FIG. 14, the probe light emitted from the displacement sensor 211a travels in the X + direction and obliquely downward, and is irradiated to the measurement point MPa between the displacement sensor 211a and the objective lens 217. When the processed surface of the workpiece 102 is a regular reflection surface, the probe light reflected at the measurement point MPa is incident on the reflection point RPa of the diffuse reflection plate 212a and diffusely reflected at the reflection point RPa. Therefore, the displacement of the workpiece 102 at the measurement point MPa offset in the X-direction from the laser processing point FP which is the focal point of the objective lens 217 can be measured by the combination of the displacement sensor 211a and the diffuse reflector 212a. When the machining direction is the X-direction, the displacement of the workpiece 102 can be prefetched by using a combination of the displacement sensor 211b and the diffuse reflector 212b.

  Similarly, the displacement of the workpiece 102 at the measurement point MPb offset in the X + direction from the laser processing point FP can be measured by the combination of the displacement sensor 211b and the diffuse reflector 212b. Therefore, when the machining direction is the X + direction, the displacement of the workpiece 102 can be prefetched by using a combination of the displacement sensor 211b and the diffuse reflector 212b.

  Further, the displacement of the workpiece 102 at the measurement point MPc offset in the Y-direction from the laser processing point FP can be measured by the combination of the displacement sensor 211c and the diffuse reflector 212c. Therefore, when the machining direction is the Y-direction, the displacement of the workpiece 102 can be prefetched by using a combination of the displacement sensor 211c and the diffuse reflector 212c.

  Furthermore, the displacement of the workpiece 102 at the measurement point MPd offset in the Y + direction from the laser processing point FP can be measured by the combination of the displacement sensor 211d and the diffuse reflector 212d. Therefore, when the machining direction is the Y + direction, the displacement of the workpiece 102 can be prefetched by using a combination of the displacement sensor 211d and the diffuse reflector 212d.

  Thus, in this embodiment, the displacement of the workpiece 102 can be prefetched even if the machining direction is any of X +, X−, Y +, and Y−.

  Further, by attaching the diffuse reflection block 501 to the objective lens 217, the structure of the processing head 115 in FIG. 1 can be simplified and miniaturized. The diffuse reflection block 501 has a shape that can be easily processed, and can be manufactured robustly and inexpensively.

  Further, since the distance between the pair of displacement sensors 211 and the diffuse reflection plate 212 can be shortened, and the measurement distance of each displacement sensor 211 can be shortened, the amount of diffuse reflected light received by each displacement sensor 211 Can be increased. As a result, the measurement accuracy of each displacement sensor 211 is improved.

  Note that when the displacement of the workpiece 102 is prefetched, the measurement point MP may protrude outside the workpiece 102 in the vicinity of the edge of the workpiece 102 and the displacement may not be measured. On the other hand, for example, the displacement sensor 211 to be used may be switched.

  For example, when the machining direction is the X + direction and the displacement of the workpiece 102 is measured using the displacement sensor 211b, the measurement point MPb is outside the workpiece 102 near the right end (X + direction end) of the workpiece 102. It will stick out. In this case, the measurement point MPb may be switched to the displacement sensor 211a to be used before it protrudes outside the workpiece 102.

  Alternatively, instead of switching the displacement sensor 211 to be used, for example, the measurement value immediately before the measurement point MP protrudes from the workpiece 102 is stored, and the stored measurement is performed while the measurement point MP protrudes from the workpiece 102. You may make it perform autofocus using a value.

  In addition, since the position of the Y-axis stage which consists of the Y-axis drive part 112 and the mounting base 113 in FIG. 1 and the position of the processing head 115 mounted on the X-axis stage are detected in real time by a linear encoder or the like, It is possible to accurately grasp the position where the measurement point MP protrudes from the workpiece 102 and perform the above-described control strictly in accordance with the position.

  In particular, when it is not necessary to perform prefetching of the displacement of the processing surface of the workpiece 102, for example, among the displacement sensors 211a to 211d in FIG. 13, the two are arranged in directions of 90 degrees with respect to the objective lens 217. Only one displacement sensor 211 and a diffuse reflector 212 corresponding to each displacement sensor 211 may be provided. That is, the displacement sensor 211a and the displacement sensor 211c, the displacement sensor 211a and the displacement sensor 211d, the displacement sensor 211b and the displacement sensor 211c, or any combination of the displacement sensor 211b and the displacement sensor 211d, and the diffusion corresponding to each displacement sensor 211 Only the reflection plate 212 may be provided.

  For example, when only the displacement sensor 211a and the displacement sensor 211c are provided, when the machining direction is the X + direction or the X-direction, the displacement of the workpiece 102 is measured using the displacement sensor 211a, and the machining direction is the Y + direction or When the direction is the Y-direction, the displacement of the workpiece 102 is measured using the displacement sensor 211c.

  In this way, the set of the displacement sensor 211 and the diffuse reflector 212 can be reduced, and the processing head 115 can be reduced in size.

  In this embodiment, since the measurement point MP can be as close as possible to the laser processing point FP, the influence of the fact that the displacement of the workpiece 102 cannot be prefetched is small.

  In addition, as shown in FIG. 15, by disposing the displacement sensor 211 and the diffusing reflection plate 212, it is possible to execute the prefetching of the displacement of the workpiece 102 using the two sets of the displacement sensor 211 and the diffusing reflection plate 212. It becomes possible.

  Specifically, in the embodiment of FIG. 15, the displacement sensor 211c and the displacement sensor 211d, and the diffuse reflector 212c and the diffuse reflector 212d are omitted from the embodiment of FIG. Further, the relative direction between the displacement sensor 211a and the displacement sensor 211b is set obliquely with respect to the X direction and the Y direction. As a result, the measurement point MPa is set in the direction between the X-direction and the Y-direction with respect to the objective lens 217 (laser processing point FP), and the measurement point MPb is set on the objective lens 217 (laser processing point FP). On the other hand, it is installed in the direction between the X + direction and the Y + direction.

  Accordingly, it is possible to pre-read the displacement of the workpiece 102 in any of the machining directions of the X + direction, the X− direction, the Y + direction, and the Y− direction using the two displacement sensors 211. Specifically, when the machining direction is the X + direction or the Y + direction, the displacement of the workpiece 102 is pre-read at the measurement point MPb using the displacement sensor 211b, and when the machining direction is the X-direction or the Y-direction, the displacement The displacement of the workpiece 102 is prefetched at the measurement point MPa using the sensor 211a.

  Note that the measurement point MPa and the measurement point MPb are set obliquely with respect to the X direction and the Y direction with respect to the laser processing point FP, so that the displacement of the position deviated from the position where the actual laser processing is performed. Is measured. However, since the deviation of the measurement position is slight, an error in the measured value of the displacement due to the deviation can be ignored.

  Further, in this case, if pre-reading is performed when laser processing is performed along the end portion of the workpiece 102, the measurement point MP may protrude from the workpiece 102. For example, when laser machining is performed in the Y + direction along the X + direction end of the workpiece 102, the measurement point MPb of the displacement sensor 211b protrudes outside the workpiece 102.

  In such a case, the other displacement sensor 211 may be used without performing prefetching. For example, in the previous example, the displacement sensor 211a may be used instead of the displacement sensor 211b to measure the displacement of the workpiece 102 at the measurement point MPa.

  The relative direction between the measurement point MPa and the measurement point MPb is arbitrary as long as it is oblique to the X direction and the Y direction. However, it is desirable to set to 45 degrees or a direction close to 45 degrees with respect to the X direction and the Y direction.

  In addition, the measurement point MPa and the measurement point MPb are not necessarily arranged at positions symmetrical to the laser processing point FP. For example, the distance between the measurement point MPa and the laser processing point FP is different from the distance between the measurement point MPb and the laser processing point FP, or the relative direction from the laser processing point FP to the measurement point MPa and the laser processing. The relative direction from the point FP to the measurement point MPb does not have to be opposite.

[Second Embodiment of Installation Method of Displacement Sensor 211 and Diffuse Reflecting Plate 212]
Next, a second embodiment of a method for installing the displacement sensor 211 and the diffuse reflector 212 will be described with reference to FIGS.

  FIG. 16 shows a configuration example of the measurement unit 601 and the moving mechanism drive system 602 that can adjust the distance between the laser processing point FP and the measurement point MP (hereinafter referred to as the pre-reading distance).

  The measurement unit 601 is configured to include a displacement sensor 211, a diffuse reflector 212, a connection member 611, and a moving mechanism 612. The displacement sensor 211 and the diffuse reflection plate 212 are connected to each other with a predetermined interval by a connection member 611. An objective lens 217 is disposed between the displacement sensor 211 and the diffuse reflection plate 212, and the displacement sensor 211, the objective lens 217, and the diffuse reflection plate 212 are disposed so as to be aligned in the processing direction.

  The moving mechanism 612 is driven by the moving mechanism drive system 602, so that the displacement sensor 211, the diffuse reflector 212, and the connection member 611 are integrated in the direction of arrow A (that is, the processing direction or the opposite direction). Move. Then, the displacement sensor 211 and the diffuse reflector 212 move in the direction of the arrow A while maintaining a gap, so that the measurement point MP moves in the direction of the arrow A, and between the measurement point MP and the laser processing point FP. The prefetch distance L is adjusted.

  The moving mechanism drive system 602 acquires information such as the processing speed and the response time of the displacement sensor 211, and calculates an appropriate value of the prefetch distance L based on the acquired information. Then, the movement mechanism drive system 602 drives the movement mechanism 612 to move the measurement unit 601 in the direction of arrow A, and adjusts the prefetch distance L to an appropriate distance.

  For example, when the processing speed is V (mm / s), the displacement of the workpiece 102 at the position processed after L / V (s) is measured. Therefore, for example, when the time required for the internal processing of the displacement sensor 211 is T1 (s) and the time required for controlling the autofocus based on the measurement result of the displacement sensor 211 is T2 (s), the moving mechanism drive system In step 602, the prefetch distance L is set so that L / V ≧ T1 + T2.

  Thereby, the prefetch distance L can be appropriately set according to the processing speed, processing time, etc., and autofocus can be performed more accurately. As a result, the processing quality of the workpiece 102 is improved.

  FIG. 17 shows an example of a method for installing the measurement unit 601. In this example, four measurement units 601a to 601d are provided.

  The measurement unit 601a is installed such that the objective lens 217 is disposed between the displacement sensor 211a and the diffuse reflector 212a, and the relative direction from the displacement sensor 211a to the diffuse reflector 212a is the X + direction. The measurement point MPa of the displacement sensor 211a is set at a position offset in the X + direction from the laser processing point FP.

  The measuring unit 601b is installed such that the objective lens 217 is disposed between the displacement sensor 211b and the diffuse reflector 212b, and the relative direction from the displacement sensor 211b to the diffuse reflector 212b is the X-direction. The measurement point MPb of the displacement sensor 211b is set at a position offset in the X-direction from the laser processing point FP.

  The measurement unit 601c is installed such that the objective lens 217 is disposed between the displacement sensor 211c and the diffuse reflector 212c, and the relative direction from the displacement sensor 211c to the diffuse reflector 212c is the Y + direction. The measurement point MPc of the displacement sensor 211c is set at a position offset in the Y + direction from the laser processing point FP.

  The measurement unit 601d is installed such that the objective lens 217 is disposed between the displacement sensor 211d and the diffuse reflector 212d, and the relative direction from the displacement sensor 211d to the diffuse reflector 212d is the Y-direction. The measurement point MPd of the displacement sensor 211d is set at a position offset in the Y-direction from the laser processing point FP.

  In order to make the figure easy to understand, the measurement points MPa to MPd are illustrated in an oblique direction with respect to the laser processing point FP, but actually, the measurement points MPa, the measurement points MPb, and The laser processing points FP are arranged in a substantially straight line in the X direction, and the measurement points MPc, the measurement points MPd, and the laser processing points FP are arranged in a substantially straight line in the Y direction.

  The processing system control system 651 controls the entire laser processing by the laser processing apparatus 101 of FIG. For example, the machining system control system 651 gives a command to the movement mechanism drive system 602 to adjust the positions of the measurement points MPa to MPd. Further, for example, the machining system control system 651 gives a command to the XY stage control unit 652 to control the machining direction, the machining speed, and the like. Further, for example, the machining system control system 651 gives a command to the AF direction control unit 653 and switches the displacement sensor 211 to be used.

  The XY stage control unit 652 controls the machining direction, the machining speed, and the like by controlling the drive system in the X direction of the Y axis drive unit 112 and the machining head 115, for example.

  The AF direction control unit 653 is provided, for example, between the displacement sensor 211 and the error amplifier 213 in FIG. Then, the AF direction control unit 653 switches the contact of the switch 654 according to the processing direction, and selects the displacement sensor 211 that supplies the measurement signal to the error amplifier 213. For example, when the machining direction is the X + direction, the displacement sensor 211a is selected. When the machining direction is the X− direction, the displacement sensor 211b is selected. When the machining direction is the Y + direction, the displacement sensor 211c is selected. Is the Y-direction, the displacement sensor 211d is selected.

  As a result, the displacement of the workpiece 102 can be prefetched regardless of whether the machining direction is any of the X + direction, the X− direction, the Y + direction, and the Y− direction. Can do.

  Note that the number of measurement units 601 can be reduced to two as shown in FIG. 18 by using the fact that the position of the measurement point MP can be adjusted.

  In the example of FIG. 18, the measurement unit 601b and the measurement unit 601d are deleted from the example of FIG. 17, and the measurement unit 601a and the measurement unit 601c are left.

  For example, when the processing direction is the X + direction, the moving mechanism drive system 602 drives the moving mechanism 612a so that the measurement point MPa is offset from the laser processing point FP in the X + direction (for example, the measurement point MPa1). The measurement unit 601a is set at the position indicated by the solid line. The AF direction control unit 653 selects the displacement sensor 211a via the switch 654.

  When the machining direction is the X-direction, the movement mechanism drive system 602 drives the movement mechanism 612a so that the measurement point MPa is offset in the X-direction from the laser machining point FP (for example, the measurement point MPa2). The measurement unit 601a is set at a position indicated by a dotted line. The AF direction control unit 653 selects the displacement sensor 211a via the switch 654.

  When the machining direction is the Y + direction, the movement mechanism drive system 602 drives the movement mechanism 612c to position the measurement unit 601c with a solid line so that the measurement point MPc is offset from the laser machining point FP in the Y + direction. Set to (measurement point MPc1). In addition, the AF direction control unit 653 selects the displacement sensor 211 c via the switch 654.

  When the machining direction is the Y-direction, the moving mechanism drive system 602 drives the moving mechanism 612c to indicate the measurement unit 601c with a dotted line so that the measurement point MPc is offset from the laser machining point FP in the Y-direction. Set to the position (measurement point MPc2). In addition, the AF direction control unit 653 selects the displacement sensor 211 c via the switch 654.

  In this way, even if the number of measurement units 601 is reduced to two, the pre-reading of the displacement of the workpiece 102 is performed in any machining direction of the X + direction, the X− direction, the Y + direction, or the Y− direction. It becomes possible to do.

  Note that the measurement unit 601a and the measurement unit 601c may be deleted, and the measurement unit 601b and the measurement unit 601d may be left.

  Similarly to the embodiment of FIG. 15, the relative direction between the measurement point MP and the laser processing point FP is set obliquely with respect to the X direction and the Y direction, as shown in FIG. The number of measurement units 601 can be reduced to one.

  Specifically, in the measurement unit 601, the objective lens 217 is disposed between the displacement sensor 211 and the diffuse reflector 212, and the relative direction from the displacement sensor 211 to the diffuse reflector 212 is oblique with respect to the X direction and the Y direction. It is installed to become. Further, the displacement sensor 211 is disposed in the direction between the X + direction and the Y + direction with respect to the objective lens 217 (laser processing point FP), and the diffuse reflector 212 is disposed with respect to the objective lens 217 (laser processing point FP). It is arranged in a direction between the X-direction and the Y-direction.

  For example, when the machining direction is the X + direction or the Y + direction, the movement mechanism drive system 602 drives the movement mechanism 612 so that the measurement point MP is offset from the laser machining point FP in the X + direction and the Y + direction (for example, , Measurement point MP1) and measurement unit 601 are set to positions indicated by solid lines.

  On the other hand, when the machining direction is the X-direction or the Y-direction, the movement mechanism drive system 602 drives the movement mechanism 612 so that the measurement point MP is offset from the laser machining point FP in the X-direction and the Y-direction. In this manner (for example, the measurement point MP2), the measurement unit 601 is set at a position indicated by a dotted line.

  In this way, even if the number of measurement units 601 is reduced to one, the pre-reading of the displacement of the workpiece 102 is performed in any machining direction of the X + direction, the X− direction, the Y + direction, or the Y− direction. It becomes possible to do. Further, the AF direction control unit 653 and the switch 654 can be deleted.

  The relative direction from the displacement sensor 211 to the diffuse reflector 212 is arbitrary as long as it is oblique to the X direction and the Y direction. For example, as shown in FIG. 20, the relative direction from the displacement sensor 211 to the diffuse reflector 212 may be set to a direction rotated 180 degrees from the example of FIG.

  However, it is desirable that the relative direction between the displacement sensor 211 and the diffuse reflector 212 is set to 45 degrees or a direction close to 45 degrees with respect to the X direction and the Y direction.

  Further, when the measurement point MP protrudes outside the workpiece 102, the measurement value immediately before protruding from the workpiece 102 is stored and used as in the embodiment of FIG. 15, or the measurement point MP does not protrude. The measuring unit 601 may be moved to the position.

  Furthermore, as shown in FIG. 21, a rotation mechanism for rotating the measurement unit 601 around the laser processing point FP is provided in parallel with the processing surface of the workpiece 102, and the measurement point MP is rotated about the laser processing point FP. You may make it make it.

  This rotation mechanism is constituted by, for example, a motor 701 and a rotation gear 702. Note that an opening 702A for allowing a processing laser beam to enter the objective lens 217 is provided at the center of the rotation gear 702.

  Then, by driving the motor 701 and rotating the rotary gear 702, the measurement unit 601 rotates around the objective lens 217 in the direction of arrow A, and the measurement point MP rotates around the laser processing point FP.

  Thereby, even if the machining direction is set in a direction other than the X direction and the Y direction, the direction in which the displacement of the workpiece 102 is pre-read can be set in accordance with the machining direction.

  In this example, the moving mechanism drive system 602 and the moving mechanism 612 can be deleted, and the adjustment function of the look-ahead distance L can be deleted.

  The mechanism for rotating the measurement unit 601 is arbitrary, and for example, it may be rotated using a hollow motor or the like.

<3. Modification>
Hereinafter, modifications of the embodiment of the present invention will be described.

  In the laser processing apparatus 101 of FIG. 1, the example in which the gantry 114 is fixed is shown. For example, the Y-axis drive unit 112 of FIG. 1 is eliminated and the gantry 114 itself is driven in the Y direction (moving gantry system stage). Also good.

  In the above description, the example using the plate-like diffuse reflection plate 212 has been described. However, a diffuse reflector having a shape other than the plate shape (for example, spherical shape) may be used.

  Further, for example, the function of the error amplifier 213 may be built in the displacement sensor 211.

  For example, the signal processing unit 234 of the displacement sensor 211 may calculate the displacement δ of the workpiece 102 based on the measurement result and output a measurement signal indicating the displacement δ. In this case, for example, the signal processing unit 234 calculates the displacement δ with respect to the diffuse reflection surface based on the above-described equation (4) based on the detection result of the reflection state of the processed surface of the workpiece 102, and the above-described equation ( The calculation method of the displacement δ with respect to the regular reflection surface based on 8) may be automatically switched.

  Further, for example, the signal processing unit 234 of the displacement sensor 211 may detect the state of reflection of the processed surface of the workpiece 102 based on whether or not the measurement distance is within the measurement range. For example, when the length measurement range for the regular reflection surface is set, when the measurement distance is out of the measurement range, it is detected that the processing surface of the workpiece 102 has changed from the regular reflection surface to the diffuse reflection surface, When the measurement range for the diffuse reflection surface is set, when the measurement distance is out of the measurement range, it can be detected that the processing surface of the workpiece 102 has changed from the diffuse reflection surface to the regular reflection surface. .

  In the above description, the example in which the position of the focal point of the objective lens 217 is adjusted by the position of the objective lens 217 in the Z direction has been described. However, in the present invention, for example, the objective lens 217 includes a plurality of lenses, and the lens The present invention can also be applied to the case where the focus position is adjusted according to the interval between them.

  Further, instead of the linear sensor 233, a two-dimensional image sensor or the like may be used.

  In the above description, the example in which the focus of the objective lens 217 is focused on the processing surface using the probe light that is regularly or diffusely reflected on the processing surface of the workpiece 102 has been described. However, according to the present invention, it is possible to focus the objective lens 217 on the processed surface using probe light that is specularly reflected or diffusely reflected on a surface different from the processed surface.

  For example, as shown by an arrow A1 in FIG. 22, a case in which processing is performed by irradiating a regular reflection film 802 (for example, a Mo film) from the glass substrate 801 side with laser light will be considered. In this case, first, as described above, the focus position can be adjusted to the surface 801a of the glass substrate 801 using the probe light diffusely reflected by the surface 801a of the glass substrate 801. At this time, by setting the focal position to be offset from the surface 801a of the glass substrate 801 by a position deeper by the thickness of the glass substrate 801, the probe light diffusely reflected on the surface 801a of the glass substrate 801 is used to actually The focal position can be adjusted to the surface 802a of the regular reflection film 802 which is a processed surface.

  For example, as indicated by an arrow A2 in FIG. 23, laser light is applied to the regular reflection film 812 from the transparent or translucent film substrate 811 (for example, a flexible sheet such as a PI sheet, a PET sheet, a COC sheet, etc.). The same applies to the processing by irradiating. That is, using the probe light diffusely reflected by the surface 811a of the film substrate 811, the focal position can be adjusted to the surface 812a of the regular reflection film 812 which is an actual processed surface.

  In addition, as shown in FIG. 24, the present invention is also applicable to a case where the focus position is adjusted to the processing surface using the probe light reflected from the processing surface deeper than the surface of the work 102 as well as the surface of the work 102. Applicable.

  Specifically, for example, the wavelength of the probe light is set to a wavelength having a good transmittance with respect to the film substrate 821, and the surface 821a of the film substrate 821 is coated so that the probe light is less likely to diffusely reflect. . Then, as indicated by an arrow A3, the probe light incident from the film substrate 821 side is transmitted through the film substrate 821 and regularly reflected by the surface 822a of the regular reflection film 822. Using the probe light specularly reflected by the surface 822 a of the regular reflection film 822, the focal position can be adjusted to the surface 822 a of the regular reflection film 822.

  For example, in the embodiment shown in FIGS. 13 and 14, when laser processing is performed obliquely with respect to the X direction and the Y direction, the surface of the diffuse reflection block 501 on which the diffuse reflection plate 212 is provided It is also possible to provide a diffuse reflector on the surface of the inverted triangle.

  Note that the present invention can also be applied to apparatuses that perform autofocus other than laser processing apparatuses.

  The embodiments of the present invention are not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 101 Laser processing apparatus 102 Work 112 Y-axis drive part 113 Mounting stage 114 Gantry 115a thru | or 115f Processing head 201 Focus adjustment apparatus 211, 211a thru | or 211d Displacement sensor 212, 212a thru | or 212d Diffuse reflector 213 Error amplifier 214 Motor driver 215 Z axis Drive motor 216 Z-axis drive screw 217 Objective lens 231 Laser light source 232 Light receiving lens 233 Linear sensor 234 Signal processing unit 301 Focus adjustment device 311 Connection member 351 Focus adjustment device 361 Mounting stand 362 Motor driver 363 Rotary encoder 451 Focus adjustment device 461 Diffusion Reflector 461A Pinhole 462 Photosensor 463 Amplification comparator 501 Diffuse reflection block 601, 601a to 601d Measurement unit 602 Mobile device Drive system 611,611a to 611d connecting member 612,612a to 612d moving mechanism 651 processing system control system 652 XY stage controller 653 AF direction control unit 654 switches 701 motor 702 rotates gear FP laser machining point MP measuring point

Claims (19)

In the focus adjustment device of the laser processing device,
An objective lens that emits a laser beam for processing;
A displacement sensor that emits measurement light and measures the displacement of the object or the distance to the object by the reflected light; and
A diffuse reflector disposed at a position where the measurement light regularly reflected on the surface of the workpiece is incident;
A focus adjustment unit that adjusts the position of the focal point of the objective lens based on the measurement result of the displacement sensor, and
When the measurement light is specularly reflected on the surface of the workpiece, the focus adjusting unit is configured to reflect the measurement light specularly reflected on the surface of the workpiece after being diffusely reflected by the diffuse reflector, and then on the surface of the workpiece. A focus adjustment device that adjusts a focal position of the objective lens based on a first measurement result measured by the displacement sensor using the reflected first reflected light. When the measurement light is diffusely reflected on the surface of the workpiece, the focus adjusting unit uses the second reflected light that is diffusely reflected on the surface of the workpiece and the second measurement result measured by the displacement sensor. The focus adjustment apparatus according to claim 1, wherein the focus position of the objective lens is adjusted based on the following. The focus adjustment unit selects whether to adjust a focus position of the objective lens with respect to either a regular reflection surface or a diffuse reflection surface based on a reflection state of the surface of the workpiece. Item 3. The focus adjustment device according to Item 2. The focus adjustment unit switches whether to adjust a focus position of the objective lens with respect to either a regular reflection surface or a diffuse reflection surface when a measurement result of the displacement sensor is out of a predetermined range. The focus adjusting apparatus according to claim 3. Two or more pairs of the displacement sensor and the diffuse reflector are provided,
The focal point according to any one of claims 1 to 4, wherein the diffuse reflector is provided between the displacement sensor and the objective lens of the same set and in the vicinity of the objective lens. Adjustment device. A first process in which the objective lens is disposed between a first displacement sensor and a second displacement sensor, and relative directions between the first displacement sensor and the second displacement sensor are orthogonal to each other. The focus adjustment apparatus according to claim 5, wherein the focus adjustment apparatus is set obliquely with respect to the direction and the second processing direction. A first relative direction of the first displacement sensor with respect to the objective lens is set to a predetermined first processing direction;
The focus adjusting apparatus according to claim 5, wherein a second relative direction of the second displacement sensor with respect to the objective lens is set to a second processing direction orthogonal to the first processing direction. . At least four pairs of the displacement sensor and the diffuse reflector are provided,
The objective lens is disposed between the first displacement sensor and the second displacement sensor and between the third displacement sensor and the fourth displacement sensor, and the first displacement sensor and the second displacement sensor. 6. The focus adjustment apparatus according to claim 5, wherein a relative direction between the first displacement sensor and the third displacement sensor is orthogonal to a third direction. The focus adjusting apparatus according to claim 5, wherein each of the diffuse reflectors is provided on a member attached around the objective lens. The focus adjustment device according to claim 1, wherein a measurement point of the displacement sensor is set in front of a focus position of the objective lens in a processing direction of the workpiece. The displacement sensor, the diffuse reflector, and the objective lens are connected;
The focal point according to any one of claims 1 to 10, further comprising a moving mechanism that moves the displacement sensor, the diffuse reflector, and the objective lens together in a direction perpendicular to the workpiece. Adjustment device. A movement amount detection unit for detecting a movement amount of the objective lens in a direction perpendicular to the workpiece;
The focus adjustment apparatus according to claim 1, wherein the focus adjustment unit adjusts a focus position of the objective lens based on a detection result of the movement amount detection unit. The objective lens is composed of a plurality of lenses,
The focus adjustment apparatus according to claim 1, wherein the focus adjustment unit adjusts a position of a focus of the objective lens by adjusting a distance between the lenses of the objective lens. The displacement sensor and the diffuse reflector are connected;
The focus adjustment apparatus according to claim 1, further comprising a moving mechanism that moves the displacement sensor and the diffuse reflector integrally with respect to the workpiece. The relative direction between the displacement sensor and the diffuse reflector is set obliquely with respect to the first processing direction and the second processing direction orthogonal to each other. Focus adjustment device. At least two sets in which the displacement sensor and the diffuse reflector are connected are provided,
A relative direction between the first set of displacement sensors and the diffuse reflector is set to a predetermined first processing direction;
The relative direction between the displacement sensor of the second set and the diffuse reflector is set to a second processing direction orthogonal to the first processing direction. Focus adjustment device. The displacement sensor and the diffuse reflector are connected;
5. The focus adjustment device according to claim 1, further comprising: a rotation mechanism that rotates the displacement sensor and the diffuse reflector integrally with the objective lens in parallel with respect to the workpiece. . The focus adjusting apparatus according to claim 17, further comprising a moving mechanism that moves the displacement sensor and the diffuse reflector integrally with respect to the workpiece. A laser processing apparatus comprising the focus adjustment apparatus according to claim 1.

Images