Measuring device, measuring method, and laser processing device

Abstract

The state of the laser beam is accurately measured by appropriately separating and receiving the measurement light generated when the laser beam is irradiated onto a light-emitting object, from the laser beam itself. [Solution] A measuring device for measuring the state of a laser beam, comprising: a light emitter that emits measuring light of a different wavelength from the wavelength of the laser beam when irradiated with the laser beam; a light receiving unit having a light receiving element that receives the measuring light; a first lens section having positive power to refract the laser beam and the measuring light that have traveled from the light emitter; a separation section that separates the laser beam and the measuring light refracted by the first lens section, guides the measuring light to a measuring optical path leading to the light receiving element, and guides the laser beam to a separation optical path that does not reach the light receiving element; and a second lens section arranged in the measuring optical path and images the measuring light separated by the separation section onto the light receiving element.

Description

Technical Field

[0001] The present invention relates to a measuring device for measuring the state of a laser beam irradiated onto a workpiece by a laser processing device, a measuring method, and a laser processing device including the measuring device.

Background Art

[0002] In the manufacturing process of device chips, a wafer in which devices are formed in a plurality of regions partitioned by a plurality of streets (division planned lines) arranged in a grid pattern is used. By dividing this wafer along the streets and fragmenting it, device chips including the devices are manufactured. The device chips are incorporated into various electronic devices such as mobile phones and personal computers.

[0003] A laser processing device is used for dividing the wafer. The laser processing device includes a holding table for holding the workpiece and a laser irradiation unit for irradiating the workpiece with a laser beam. The laser irradiation unit incorporates an optical system composed of various optical elements (mirrors, lenses, etc.), and the laser beam is guided to the workpiece by the optical system. For example, by irradiating the workpiece with a laser beam having a wavelength that can be absorbed by the workpiece, ablation processing is performed on the workpiece, and the workpiece is divided.

[0004] A measuring device for measuring the state such as the intensity distribution and shape of the laser beam irradiated onto the workpiece by the laser processing device is known (see Patent Document 1). In the laser processing device, in order to appropriately laser-process the workpiece with the laser beam, the state of the laser beam is periodically measured by the measuring device.

[0005] This measuring device comprises a phosphor that emits fluorescence that becomes measurement light when irradiated with a laser beam, a separation element that separates the measurement light generated by the phosphor from the laser beam, a photodetector (image sensor) that receives the measurement light, and a lens group (objective lens and imaging lens) that forms an image of the measurement light on the photodetector. In this measuring device, the separation element is placed between the phosphor and the objective lens. The intensity distribution and shape of the laser beam are then measured by measuring the two-dimensional intensity distribution of the measurement light with the photodetector. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Patent No. 6244502 [Overview of the project] [Problems that the invention aims to solve]

[0007] However, in a separation element of a measuring device configured in this way, the separation element that separates the laser beam and the measuring light has a separation surface where separation occurs. Furthermore, the measuring light and the laser beam have a predetermined diameter. The measuring light and the laser beam are incident on this separation surface at an angle, but the angle of incidence differs slightly depending on the position of the measuring light, etc., in the cross-section upon reaching the separation surface.

[0008] The dielectric multilayer film used on the separation surface of the separation element exhibits different reflectivity and transmittance depending on the angle of incidence of the incident light, thus determining an optimal angle of incidence suitable for separation. Therefore, if the laser beam and measurement light are incident on the separation surface at different angles of incidence depending on their position in the cross-section, the laser beam and measurement light will not be properly separated at the separation surface as intended.

[0009] For example, if the laser beam that should be separated is not completely separated, that is, if the measurement light is not pure enough, the measurement light may be incident on the photodetector. When the laser beam is mixed with the measurement light, the laser beam becomes a noise source, making it impossible to accurately measure the shape of the measurement light. In addition, the photodetector may be damaged by the laser beam.

[0010] Furthermore, some of the measurement light that should be directed towards the photodetector may not reach it. In this case, the intensity of the measurement light received by the photodetector may be insufficient, potentially making it impossible to accurately measure the shape (intensity distribution) of the measurement light.

[0011] The present invention has been made in view of the above problems, and aims to provide a measuring device, a measuring method, and a laser processing apparatus equipped with the measuring device that can appropriately measure the state of a laser beam by appropriately separating and receiving the measuring light generated when the laser beam is irradiated onto a light-emitting object from the laser beam. [Means for solving the problem]

[0012] According to one aspect of the present invention, a measuring device for measuring the state of a laser beam is provided, comprising: a light emitter that emits measuring light of a different wavelength from the wavelength of the laser beam when irradiated with the laser beam; a light receiving unit having a light receiving element that receives the measuring light; a first lens section having positive power that refracts the laser beam and the measuring light that have traveled from the light emitter; a separation section that separates the laser beam and the measuring light refracted by the first lens section, guides the measuring light to a measuring optical path leading to the light receiving element, and guides the laser beam to a separation optical path that does not reach the light receiving element; and a second lens section arranged in the measuring optical path and images the measuring light separated by the separation section onto the light receiving element.

[0013] Preferably, the separation unit is a dichroic mirror that reflects the measuring light and transmits the laser beam.

[0014] Alternatively, preferably, the separation unit is a dichroic mirror that transmits the measuring light and reflects the laser beam.

[0015] More preferably, the device further includes a spacing adjustment unit for adjusting the distance between the focal point of the first lens portion and the light-emitting element.

[0016] Preferably, the first lens portion is a lens made of quartz or calcium fluoride.

[0017] Preferably, the second lens portion includes an achromatic lens.

[0018] According to another aspect of the present invention, a laser processing apparatus is provided for irradiating an object to be processed with a laser beam, comprising: a holding table for holding the object to be processed; a laser irradiation unit equipped with a light concentrator capable of focusing the laser beam onto the object to be processed held by the holding table; and the above-described measuring device, wherein the light concentrator is capable of focusing the laser beam and irradiating the light-emitting element of the measuring device.

[0019] Preferably, the system further includes a moving unit for moving the focusing point of the light condenser and the light-emitting element of the measuring device relative to each other.

[0020] More preferably, the holding table is movable together with the measuring device by the moving unit.

[0021] Furthermore, according to yet another aspect of the present invention, a measurement method is provided for measuring the shape of a laser beam using the above-described measuring device, comprising: an irradiation step of irradiating the light-emitting element with the laser beam; and a measurement step after the irradiation step of measuring the shape of the laser beam based on the shape of the measuring light imaged on the light-receiving element.

[0022] According to yet another aspect of the present invention, a measurement method for measuring the state of a laser beam, comprising: a measurement light generation step of irradiating a light-emitting body that emits measurement light of a different wavelength from the wavelength of the laser beam when irradiated with the laser beam to generate the measurement light; a first refraction step of refracting the laser beam and the measurement light that have traveled from the light-emitting body with a first lens portion having positive power; and separating the laser beam and the measurement light refracted by the first lens portion with a separation portion, guiding the measurement light to a measurement optical path, and the laser A measurement method is provided, comprising: a separation step of guiding a beam to a separation optical path; a second refraction step of imaging the measurement light separated in the separation section by a second lens section placed in the measurement optical path onto a photodetector; a light receiving step of receiving the measurement light refracted in the second refraction step with the photodetector; and an evaluation step of evaluating the state of the laser beam from the two-dimensional distribution of the measurement light received by the photodetector in the light receiving step, wherein the laser beam guided to the separation optical path in the separation step does not reach the photodetector. [Effects of the Invention]

[0023] In a measuring device, measuring method, and laser processing apparatus according to one aspect of the present invention, a laser beam is irradiated onto a light-emitting element to generate measuring light with a different wavelength from the laser beam. The laser beam and measuring light propagating from the light-emitting element are refracted by a first lens unit and separated in a separation unit. In the separation unit, the measuring light is guided to a measuring optical path leading to a photodetector, and the laser beam is guided to a separation optical path that does not reach the photodetector. Then, the measuring light is imaged onto a photodetector by a second lens unit located in the measuring optical path, and the measuring light is received by a photodetector unit.

[0024] In particular, the measurement light generated by the light emitter is refracted by the first lens unit having positive power to be made close to parallel light and is incident on the separation unit. Therefore, the measurement light is incident on the separation unit at a more uniform incident angle over the entire cross-section. As a result, the separation unit exhibits performance as planned, the laser beam and the measurement light are appropriately separated, the intensity of the laser beam mixed in the measurement light separated by the separation unit is reduced, and on the other hand, the measurement light reaches the light receiving element with sufficient intensity and purity. Therefore, the measurement light is appropriately measured.

[0025] Therefore, according to one aspect of the present invention, there are provided a measuring device, a measuring method, and a laser processing device including the measuring device that can appropriately measure the state of a laser beam by appropriately separating and receiving the measurement light generated by irradiating the light emitter with the laser beam from the laser beam.

Brief Description of the Drawings

[0026] [Figure 1] It is a perspective view showing a laser processing device. [Figure 2] It is a perspective view showing a workpiece. [Figure 3] It is a plan view schematically showing a configuration example of an optical system of a measuring device. [Figure 4] FIG. 4(A) is a flowchart showing the flow of each step of a measuring method for measuring the shape (state) of a laser beam, and FIG. 4(B) is a flowchart showing the flow of each step of a measuring method for measuring the state of a laser beam.

Embodiments for Carrying Out the Invention

[0027] Hereinafter, an embodiment according to one aspect of the present invention will be described with reference to the attached drawings. First, an example of the configuration of a laser processing apparatus in which the measuring device according to this embodiment is used will be described. Figure 1 is a perspective view showing the laser processing apparatus 2. In Figure 1, the X-axis direction (processing feed direction, first horizontal direction, left-right direction) and the Y-axis direction (indexing feed direction, second horizontal direction, front-back direction) are perpendicular to each other. Also, the Z-axis direction (up-down direction, height direction, vertical direction) is perpendicular to the X-axis direction and the Y-axis direction.

[0028] The laser processing device 2 includes a base 4 that supports each component of the laser processing device 2. The upper surface of the base 4 is a flat surface that is generally parallel to the horizontal plane (XY plane), and a moving unit (moving mechanism) 6 is provided on the upper surface of the base 4. The moving unit 6 includes a Y-axis moving unit (Y-axis moving mechanism) 8 and an X-axis moving unit (X-axis moving mechanism) 18.

[0029] The Y-axis movement unit 8 includes a pair of Y-axis guide rails 10 arranged along the Y-axis direction on the upper surface of the base 4. A flat Y-axis movement table 12 is mounted on the pair of Y-axis guide rails 10 so as to be slidable along the Y-axis guide rails 10.

[0030] A nut (not shown) is provided on the underside (bottom) of the Y-axis moving table 12. A Y-axis ball screw 14, which is positioned along the Y-axis direction between a pair of Y-axis guide rails 10, is screwed into this nut. A Y-axis pulse motor 16 is connected to the end of the Y-axis ball screw 14. When the Y-axis pulse motor 16 rotates the Y-axis ball screw 14, the Y-axis moving table 12 moves along the Y-axis guide rails 10 in the Y-axis direction.

[0031] The X-axis movement unit 18 includes a pair of X-axis guide rails 20 arranged along the X-axis direction on the surface (upper surface) side of the Y-axis movement table 12. A flat X-axis movement table 22 is mounted on the pair of X-axis guide rails 20 so as to be slidable along the X-axis guide rails 20.

[0032] A nut (not shown) is provided on the underside (bottom) of the X-axis moving table 22. An X-axis ball screw 24, which is positioned along the X-axis direction between a pair of X-axis guide rails 20, is screwed into this nut. An X-axis pulse motor 26 is connected to the end of the X-axis ball screw 24. When the X-axis pulse motor 26 rotates the X-axis ball screw 24, the X-axis moving table 22 moves along the X-axis guide rails 20 in the X-axis direction.

[0033] A holding table (chuck table) 28 is connected to the moving unit 6. The holding table 28 is placed on the surface (top surface) of the X-axis moving table 22 and holds the workpiece 11, which is the object to be laser processed by the laser processing device 2.

[0034] Figure 2 is a perspective view showing the workpiece 11. For example, the workpiece 11 is a disc-shaped wafer made of a semiconductor material such as single-crystal silicon, and has a surface 11a and a back surface 11b that are generally parallel to each other. The workpiece 11 is divided into multiple rectangular regions by multiple streets (division lines) 13 arranged in a grid pattern so as to intersect each other. Devices 15 such as ICs (Integrated Circuits), LSIs (Large Scale Integrations), LEDs (Light Emitting Diodes), and MEMS (Micro Electro Mechanical Systems) devices are formed on the surface 11a side of each of the multiple regions divided by the streets 13.

[0035] However, there are no restrictions on the type, material, shape, structure, size, etc., of the workpiece 11. For example, the workpiece 11 may be a substrate (wafer) made of semiconductors other than silicon (GaAs, InP, GaN, SiC, etc.), sapphire, glass, ceramics, resin, metal, etc. Furthermore, there are no restrictions on the type, number, shape, structure, size, arrangement, etc., of the devices 15, and the workpiece 11 does not need to have devices 15 formed on it.

[0036] When processing the workpiece 11 with the laser processing device 2 (see Figure 1), the workpiece 11 is supported by an annular frame 17 for ease of handling (transportation, holding, etc.). The frame 17 is made of a metal such as SUS (stainless steel), and a circular opening 17a is provided in the center of the frame 17, penetrating the frame 17 in the thickness direction. The diameter of the opening 17a is larger than the diameter of the workpiece 11.

[0037] A circular sheet 19 is fixed to the workpiece 11 and the frame 17. For example, the sheet 19 may be a tape containing a circularly formed film-like base material and an adhesive layer (glue layer) provided on the base material. The base material is made of a resin such as polyolefin, polyvinyl chloride, or polyethylene terephthalate. The adhesive layer is made of an epoxy, acrylic, or rubber-based adhesive. The adhesive layer may also be made of an ultraviolet-curable resin.

[0038] With the object to be processed 11 positioned inside the opening 17a of the frame 17, the central part of the sheet 19 is attached to the back surface 11b of the object to be processed 11, and the outer edge of the sheet 19 is attached to the frame 17. As a result, the object to be processed 11 is supported by the frame 17 via the sheet 19.

[0039] As shown in Figure 1, the upper surface of the holding table 28 is a flat surface that is generally parallel to the horizontal plane (XY plane), and constitutes the holding surface 28a for holding the workpiece 11. The holding surface 28a is connected to a suction source (not shown), such as an ejector, via a flow path (not shown), a valve (not shown), etc., formed inside the holding table 28. In addition, a plurality of clamps 30 are provided around the holding table 28 to grip and fix the frame 17.

[0040] When the Y-axis moving table 12 is moved along the Y-axis, the holding table 28 moves along the Y-axis. Similarly, when the X-axis moving table 22 is moved along the X-axis, the holding table 28 moves along the X-axis. Furthermore, the holding table 28 is connected to a rotational drive source (not shown), such as a motor, which rotates the holding table 28 around a rotation axis that is roughly parallel to the Z-axis.

[0041] A rectangular parallelepiped support structure 32 is provided at the rear end of the base 4 (behind the movable unit 6 and the holding table 28). The support structure 32 is formed to protrude upward from the upper surface of the base 4, and the surface (front) of the support structure 32 is arranged along the XZ plane. A columnar support member 34 is connected to the support structure 32, protruding forward from the surface of the support structure 32.

[0042] The laser processing device 2 is equipped with a laser irradiation unit 36 ​​that irradiates the object to be processed 11 with a laser beam. The laser irradiation unit 36 ​​includes a laser oscillator 35. The laser oscillator 35 has, for example, Nd:YAG, Nd:YVO4, etc. as the laser medium. The laser oscillator 35 emits a single-pulse laser beam (for example, with a repetition frequency of several tens of MHz) with a wavelength that penetrates the object to be processed 11 or a wavelength that is absorbed by the object to be processed 11.

[0043] The laser irradiation unit 36 ​​includes a laser processing head 38 mounted on the tip of the support member 34. The laser beam, which originates from the laser oscillator 35, is irradiated from the laser processing head 38 onto the workpiece 11 held by the holding table 28, thereby performing laser processing on the workpiece 11. For example, the laser processing head 38 incorporates a light condenser (focusing lens) to focus the laser beam onto the workpiece 11.

[0044] An imaging unit (not shown) may be provided at the tip of the support member 34. The imaging unit is equipped with an image sensor such as a CCD (Charged-Coupled Devices) sensor or a CMOS (Complementary Metal-Oxide-Semiconductor) sensor and captures images of the workpiece 11 held by the holding table 28. There are no restrictions on the type of imaging unit; for example, a visible light camera or an infrared camera can be used. Based on the image acquired by imaging the workpiece 11 with the imaging unit, the workpiece 11 and the laser processing head 38 are aligned.

[0045] The support member 34 may be connected to the support structure 32 via a Z-axis movement unit (not shown) that moves the support member 34 along the Z-axis direction. For example, a ball screw type movement mechanism may be installed on the front side of the support structure 32 as the Z-axis movement unit. In this case, the Z-axis movement unit moves (raises and lowers) the support member 34 along the Z-axis direction, thereby adjusting the height of the focal point of the laser beam emitted from the laser processing head 38 and focusing the imaging unit.

[0046] Furthermore, the laser processing device 2 is equipped with a display unit (display unit, display device) 40 that displays various information related to the laser processing device 2. For example, a touch panel may be used as the display unit 40. In this case, the touch panel displays an operation screen for inputting information into the laser processing device 2, and the operator can input information into the laser processing device 2 by touching the touch panel. In other words, the touch panel also functions as an input unit (input unit, input device) for inputting various information into the laser processing device 2 and is used as a user interface. However, the input unit may be an input device such as a mouse or keyboard that is provided separately and independently from the display unit 40.

[0047] Furthermore, the laser processing device 2 includes a notification unit (notification section, notification device) 42 for notifying the operator of information. For example, the notification unit 42 is an indicator light (warning light), which lights up or flashes when an abnormality occurs in the laser processing device 2 to notify the operator of the error. However, there are no restrictions on the type of notification unit 42. For example, the notification unit 42 may be a speaker that notifies the operator of information by sound or voice.

[0048] Furthermore, the laser processing device 2 includes a controller (control unit, control unit, control device) 44 that controls the laser processing device 2. The controller 44 is connected to each component that makes up the laser processing device 2 (moving unit 6, holding table 28, clamp 30, laser irradiation unit 36, display unit 40, notification unit 42, etc.). The controller 44 operates the laser processing device 2 by outputting control signals to each component of the laser processing device 2.

[0049] For example, the controller 44 is comprised of a computer. Specifically, the controller 44 includes a processing unit that performs calculations and other processing necessary for the operation of the laser processing unit 2, and a storage unit that stores various information (data, programs, etc.) used for the operation of the laser processing unit 2. The processing unit includes a processor such as a CPU (Central Processing Unit). The storage unit includes memory such as ROM (Read Only Memory) and RAM (Random Access Memory).

[0050] When processing the workpiece 11, it is first held by the holding table 28. For example, the workpiece 11 is placed on the holding table 28 such that its front surface 11a is exposed upwards and its back surface 11b (sheet 19 side) faces the holding surface 28a. The frame 17 is also fixed by multiple clamps 30. In this state, when the suction force (negative pressure) of the suction source is applied to the holding surface 28a, the workpiece 11 is held by the holding table 28 via the sheet 19.

[0051] Next, a laser beam is irradiated from the laser processing head 38 onto the workpiece 11. This applies a predetermined laser processing to the workpiece 11. The irradiation conditions of the laser beam are set appropriately according to the content of the laser processing to be applied to the workpiece 11.

[0052] For example, the irradiation conditions of the laser beam are set so that the workpiece 11 can be laser-processed. Specifically, the wavelength of the laser beam is set so that a portion of the laser beam penetrates the workpiece 11. That is, the laser beam is penetrating to the workpiece 11. In addition, other irradiation conditions of the laser beam are set appropriately so that the workpiece 11 is subjected to appropriate laser processing. For example, the irradiation conditions of the laser beam can be set as follows. Wavelength: 1064nm Average output: 0.3W Pulse repetition frequency: 80kHz Machining feed rate: 300 mm / s

[0053] Then, by positioning the focal point of the laser beam inside the workpiece 11 and irradiating the laser beam along the street 13 (see Figure 2), a modified layer can be formed inside the workpiece 11 along the street 13. This modified layer serves as a starting point for dividing the workpiece 11.

[0054] Specifically, first, the holding table 28 is rotated to align the length of the predetermined street 13 with the X-axis direction. Then, the position of the holding table 28 in the Y-axis direction is adjusted so that the focusing position of the laser beam coincides with the position of the predetermined street 13 in the Y-axis direction.

[0055] Then, while irradiating a laser beam from the laser processing head 38, the holding table 28 is moved along the X-axis (processing feed). As a result, the holding table 28 and the laser processing head 38 move relative to each other along the X-axis, and the laser beam is irradiated along the street 13. Subsequently, by repeating the same procedure, the laser beam is irradiated along all of the street 13.

[0056] As described above, when a laser beam is irradiated onto the workpiece 11, a modified layer is formed along the street 13 of the workpiece 11. When the modified layer is formed, cracks may extend from the modified layer into the interior of the workpiece 11. Alternatively, cracks may extend from the modified layer due to force or impact applied to the workpiece 11 later. When the cracks connect from the surface 11a to the back surface 11b of the workpiece 11, the workpiece 11 is divided.

[0057] The wavelength of the laser beam irradiated onto the workpiece 11 by the laser processing device 2 may be set so that the workpiece 11 absorbs the laser beam. In this case, when the laser beam is focused onto the workpiece 11, ablation occurs and dividing grooves are formed on the workpiece 11. When dividing grooves are formed on the workpiece 11 along the street 13, the workpiece 11 is divided.

[0058] When the workpiece 11 is divided along street 13, multiple device chips, each equipped with a device 15 (see Figure 2), are manufactured. If it is difficult to divide the workpiece 11 with a single laser beam irradiation, the laser beam may be irradiated multiple times along each street 13.

[0059] In the laser processing apparatus 2, the state of the laser beam is periodically checked so that multiple workpieces 11 can be processed continuously and stably. The laser processing apparatus 2 shown in Figure 1 is equipped with a measuring device 46 according to this embodiment that can measure the state of the laser beam. The measuring device 46 is, for example, installed on the X-axis moving table 22 on which the holding table 28 is mounted.

[0060] When the Y-axis moving table 12 is moved along the Y-axis, the measuring device 46 moves along the Y-axis along with the holding table 28. Similarly, when the X-axis moving table 22 is moved along the X-axis, the measuring device 46 moves along the X-axis along with the holding table 28. In other words, in the laser processing device 2, the holding table 28 is movable together with the measuring device 46 by a moving unit.

[0061] Next, the measuring device 46 according to this embodiment will be described. The measuring device 46 according to this embodiment measures the state of the laser beam when it is irradiated from the laser irradiation unit 36. Figure 3 is a schematic plan view showing an example of the configuration of the measuring device 46. Figure 3 shows an example of the configuration when the measuring device 46 is realized with the simplest optical system. Therefore, the measuring device 46 may also include lenses, mirrors, and other optical components in addition to the configuration described below.

[0062] The measuring device 46 includes a light-emitting body 48 that emits measuring light 39 with a wavelength different from that of the laser beam 37 when irradiated with the laser beam 37. The light-emitting body 48 has a support substrate 50 and a light-emitting thin film 52 supported on the support substrate 50. The light-emitting thin film 52 is made of a light-emitting material that emits light with a wavelength different from that of the laser beam 37 when irradiated with the laser beam 37. Fluorescent materials can be used as the light-emitting material contained in the light-emitting thin film 52.

[0063] The light-emitting substance (fluorescent material) contained in the light-emitting thin film 52 may be, for example, Nd:YAG or Yb:YAG with added chromium ions. Alternatively, the light-emitting substance (fluorescent material) is a material that converts infrared light wavelengths into visible light, and is an upconversion phosphor that converts long-wavelength light into short-wavelength light.

[0064] Examples of such light-emitting materials (fluorescent materials) include TYPE PTIR475 / UF (manufactured by UVIX), which converts infrared light with wavelengths of approximately 950 nm and 980 nm into blue visible light with a wavelength of approximately 480 nm; TYPE PTIR545 / UF (manufactured by UVIX), which converts infrared light with wavelengths of approximately 950 nm and 980 nm into green visible light with wavelengths of approximately 548 nm and 554 nm; TYPE PTIR660 / UF (manufactured by UVIX), which converts infrared light with wavelengths of approximately 950 nm and 975 nm into red visible light with wavelengths of approximately 661 nm, 676 nm and 683 nm; and TYPE PTIR660 / UF, which converts infrared light with a wavelength of approximately 1550 nm into red visible light with a wavelength of approximately 670 nm. Examples include PTIR545 / N (manufactured by UVIX) and YAGLASS (manufactured by SUMITA), which converts infrared light with a wavelength of approximately 1060 nm into visible light of green (wavelength approximately 550 nm) or red (wavelength approximately 660 nm). Alternatively, for example, "YAGLASS-T," a nanocrystal-containing glass manufactured by Sumita Optical Glass Co., Ltd., can be used. However, the luminescent material is not limited to these. Furthermore, the luminescent material may emit light through a process different from fluorescence upon receiving the laser beam 37. In other words, the luminescent material contained in the luminescent thin film 52 is not limited to fluorescent materials.

[0065] The light emitted from the luminescent thin film 52, which is generated when the laser beam 37 is irradiated, has a different wavelength from the laser beam 37 and reflects the properties (state) of the laser beam 37. Therefore, this light is used in the measuring device 46 according to this embodiment to measure the state of the laser beam 37. Hereinafter, this light will be referred to as measuring light 39.

[0066] When the laser beam 37 is focused inside the light-emitting thin film 52, measurement light 39 is generated from the light-emitting thin film 52. If the area where measurement light 39 is generated becomes too large, the observation image obtained when the measurement light 39 is finally received by the light-receiving unit may become unclear, the resolution may decrease, or the error in the received light intensity may increase. Therefore, in order to measure the state of the laser beam 37 with high precision, it is preferable that the area in the light-emitting thin film 52 where measurement light 39 is generated is small.

[0067] When the laser beam 37 is focused into the light-emitting thin film 52 by the light-gathering unit 36, the cross-sectional area of ​​the laser beam 37 in a plane perpendicular to the direction of propagation of the laser beam 37 increases as the plane moves further away from the focal point. Therefore, in order to reduce the area in the light-emitting thin film 52 where measurement light 39 is generated, it is preferable that the light-emitting thin film 52 be thin.

[0068] If the light-emitting thin film 52 is sufficiently thin, the region through which the laser beam 37 passes can be limited. More specifically, if the light-emitting thin film 52 is sufficiently thin, the laser beam 37 enters the light-emitting thin film 52 with a sufficiently small cross-sectional area, and the laser beam 37 exits the light-emitting thin film 52 before it can spread out significantly after passing the focal point.

[0069] Therefore, the thickness of the light-emitting thin film 52 provided by the light-emitting body 48 is preferably determined by referring to the depth of focus of the light-emitting lens, which is calculated based on the numerical aperture (NA) value of the light-emitting lens provided on the laser processing head 38 and the wavelength of the laser beam 37. The depth of focus is calculated by dividing the wavelength of the laser beam 37 by the square of the numerical aperture (NA). It is then possible to set the thickness of the light-emitting thin film 52 to be less than or equal to the calculated depth of focus value.

[0070] For example, when a laser beam 37 is irradiated onto a workpiece 11 to form dividing grooves by ablation and divide the workpiece 11, the wavelength of the laser beam 37 is set to 0.193 μm to 0.800 μm. The numerical aperture (NA) of the condenser (focusing lens) provided on the laser processing head 38 used in this case is set to 0.15 to 0.5. The depth of focus calculated from these values ​​is 0.772 μm to 35.6 μm. Therefore, it is conceivable that the thickness of the light-emitting thin film 52 be set to be less than or equal to this depth of focus value.

[0071] Furthermore, for example, when a laser beam 37 is irradiated onto the workpiece 11 to form a modified layer and divide the workpiece 11, the wavelength of the laser beam 37 is set to 0.532 μm to 1.600 μm. The numerical aperture (NA) of the condenser (focusing lens) provided on the laser processing head 38 used in this case is set to 0.5 to 0.9. The depth of focus calculated from these values ​​is 0.657 μm to 6.40 μm. Therefore, it is conceivable that the thickness of the light-emitting thin film 52 be set to be less than or equal to this depth of focus value.

[0072] However, even when the light-emitting thin film 52 has a thickness that exceeds the depth of focus to a certain extent, it may still be possible to adequately measure the state of the laser beam 37. Therefore, for example, the thickness of the light-emitting thin film 52 is preferably 25% greater than the depth of focus or less, more preferably 15% greater than the depth of focus or less, and even more preferably 10% greater than the depth of focus or less.

[0073] For example, if the wavelength of the laser beam 37 is 1064 nm and the numerical aperture of the focuser of the laser irradiation unit 36 ​​is 0.6, the depth of focus will be 2.96 μm. The thickness of the light-emitting thin film 52 is preferably determined by referring to this depth of focus. For example, the thickness of the light-emitting thin film 52 is preferably 3.70 μm or less, which is 25% greater than the depth of focus, preferably 3.70 μm or less, which is 15% greater than the depth of focus, more preferably 3.40 μm or less, and even more preferably 3.26 μm or less, which is 10% greater than the depth of focus.

[0074] Furthermore, the thickness of the light-emitting thin film 52 can be set to less than or equal to the depth of focus, which is 2.96 μm. For example, the thickness of the light-emitting thin film 52 can be set to 2.00 μm. In this case, the state of the laser beam 37 can be measured with extremely high precision. However, the thickness of the light-emitting thin film 52 is not limited to these values.

[0075] The support substrate 50 for the light-emitting element 48 can be made of a material that can transmit the laser beam 37 and the measurement light 39 well. For example, quartz or calcium fluoride can be used for the support substrate 50. However, the material of the support substrate 50 is not limited to these. The thickness of the support substrate 50 should be such that the light-emitting thin film 52 can be formed with high precision at the aforementioned thickness and that the support substrate 50 can be adequately supported.

[0076] The light-emitting element 48 is manufactured by forming a light-emitting thin film 52 on a support substrate 50, for example, by sputtering, vapor deposition, or other methods. The thickness of the light-emitting thin film 52 in the light-emitting element 48 can be allowed to vary by approximately ±10% in a 0.5 mm square area where the laser beam 37 is expected to be irradiated. Preferably, the variation in the thickness of the light-emitting thin film 52 is approximately ±0.5%.

[0077] The laser beam 37 irradiated onto the measuring device 46 by the laser irradiation unit 36 ​​is focused onto the light emitter 48. When the laser beam 37 is focused onto the light-emitting thin film 52 of the light emitter 48, a portion of it is absorbed by the light-emitting thin film 52, generating measurement light 39 from the light-emitting thin film 52. The measurement light 39 and the laser beam 37 that has passed through the light-emitting thin film 52 then travel through the support substrate 50 and diffuse to the outside of the light emitter 48.

[0078] The measuring device 46 according to this embodiment includes a first lens section 54 having positive power to refract the laser beam 37 and measuring light 39 propagating from the light emitter 48. The first lens section 54 has the function of bringing the diffusing measuring light 39 and laser beam 37 closer to parallel light with positive power.

[0079] The first lens section 54 is composed of one or more lenses 56a, 56b having positive power. For example, lenses 56a, 56b are plano-convex lenses, and the laser beam 37 enters lenses 56a, 56b from the flat surface and exits from the convex surface.

[0080] Furthermore, the measuring device 46 further includes a spacing adjustment unit 58 for adjusting the distance between the focal point of the first lens unit 54 and the light-emitting element 48 (light-emitting thin film 52). The spacing adjustment unit 58 adjusts the position of the first lens unit 54 relative to the light-emitting element 48 so that the focal point of the first lens unit 54 aligns with the light-emitting element 48 (light-emitting thin film 52). In particular, it is preferable that the focal point of the first lens unit 54 be aligned with the generation point of the measurement light 39 (the focusing point of the laser beam 37) by the spacing adjustment unit 58.

[0081] Here, the spacing adjustment unit 58 is preferably a piezoelectric drive device. A piezoelectric drive device is a drive device that uses a piezoelectric element, which is a piezoelectric element that expands and contracts when a voltage is applied. The focus of the first lens unit 54 is controlled by the voltage applied to the piezoelectric element.

[0082] Furthermore, the spacing adjustment unit 58 is, for example, a ball screw type moving mechanism (spacing change mechanism) not shown. Specifically, the spacing adjustment unit 58 includes a guide rail extending along the direction of travel of the laser beam 37 and measuring light 39 that travel from the light emitter 48 to the first lens unit 54, and a slide body that is slidably mounted on the guide rail and to which the first lens unit 54 is fixed. In addition, the spacing adjustment unit 58 includes a ball screw that extends along the guide rail and is screwed into a nut provided on the slide body, and a motor (rotation drive source) connected to one end of the ball screw that rotates the ball screw around the direction of extension.

[0083] If the spacing adjustment unit 58 is a ball screw type moving mechanism, the motor connected to the ball screw is activated to rotate the ball screw, causing the sliding body to which the first lens unit 54 is fixed to move along the guide rail together with the first lens unit 54. This adjusts the distance between the focal point of the first lens unit 54 and the light-emitting body 48.

[0084] If the first lens section 54 is composed of multiple lenses 56a, 56b, the spacing adjustment section 58 may be composed of multiple moving mechanisms that move each lens 56a, 56b individually. In this case, each lens 56a, 56b can be moved independently. Also, if the distance between the focal point of the first lens section 54 and the light-emitting body 48 can be adjusted by moving only some of the lenses 56a, 56b, the spacing adjustment section 58 may be composed of one or more moving mechanisms that move some of the lenses 56a, 56b.

[0085] Thus, the spacing adjustment unit 58 is a spacing adjustment mechanism that moves the first lens unit 54 and the light-emitting body 48 relative to each other. However, the spacing adjustment unit 58 is not limited to this. The spacing adjustment unit 58 may be composed of an additional lens disposed between the first lens unit 54 and the light-emitting body 48. That is, the spacing adjustment unit 58 may adjust the distance between the focal point of the first lens unit 54 and the light-emitting body 48 (light-emitting thin film 52) by inserting an additional lens into the optical path between the first lens unit 54 and the light-emitting body 48, or by removing an additional lens from the optical path.

[0086] Furthermore, if the transparency of the first lens portion 54 (lenses 56a, 56b) to the laser beam 37 is not sufficiently high, a portion of the laser beam 37 will be absorbed by the first lens portion 54 as it passes through it. This will cause the temperature of the first lens portion 54 to rise significantly. When the temperature of the first lens portion 54 rises, a phenomenon called the thermal lens effect occurs, in which the refractive index of the first lens portion 54 changes, altering its performance.

[0087] Therefore, it is preferable that the first lens portion 54 (lenses 56a, 56b) be made of a material that can transmit the laser beam 37 well. For example, the first lens portion 54 is preferably made of quartz or calcium fluoride. In this case, the thermal lensing effect is less likely to occur in the first lens portion 54.

[0088] The measuring light 39 and laser beam 37, which depart from the light-emitting element 48 and travel while diffusing, are refracted by the first lens section 54, which has positive power, and are brought closer to parallel light. Preferably, they are converted into parallel light. After departing from the first lens section 54, they reach the separation section 60.

[0089] The measuring device 46 includes a separation unit 60 that separates the laser beam 37 and the measuring light 39 refracted by the first lens unit 54. The separation unit 60 is, for example, a dichroic mirror 62 that reflects the measuring light 39 and transmits the laser beam 37.

[0090] For example, a dielectric multilayer film is provided on the separation surface 64 of the separation unit 60 (dichroic mirror 62), so that only the measurement light 39 is reflected by the separation surface 64, and the laser beam 37 passes through the separation surface 64. The separation unit 60 guides the measurement light 39 to the measurement optical path 66 leading to the photodetector 78 described later, and guides the laser beam 37 to the separation optical path 68 which does not reach the photodetector 78.

[0091] Here, at the separation surface 64 of the dichroic mirror 62, the reflectance and transmittance of light differ depending on the angle of incidence of the light, and an optimal angle of incidence is determined for separating the laser beam 37 and the measurement light 39. If the first lens portion 54 does not exist and the laser beam 37 and the measurement light 39 are not brought close to parallel light, a large difference in the angle of incidence of the measurement light 39, etc. will occur at various points on the separation surface 64.

[0092] In this case, the laser beam 37 and the measurement light 39 are not properly separated, and the measurement light 39 travels through the measurement light path 66 without sufficient separation of the laser beam 37, while some of the measurement light 39 travels through the separation light path 68.

[0093] In contrast, in the measuring device 46 according to this embodiment, the laser beam 37 and the measuring light 39 are incident on the separation surface 64 of the dichroic mirror 62 in a state where they are brought closer to parallel light by the first lens section 54. As a result, the incident angles of the measuring light 39 and the like are brought closer to uniform at various points on the separation surface 64, and the laser beam 37 and the measuring light 39 are appropriately separated on the separation surface 64.

[0094] The separation unit 60 may be equipped with a dichroic mirror instead of the dichroic mirror 62 described above, which has the property of reflecting the laser beam 37 and transmitting the measurement light 39 at the separation surface. The path of the light reflected from the separation surface may be used as the separation optical path, and the path of the light transmitted through the separation surface may be used as the measurement optical path.

[0095] Here, we will describe in detail the dichroic mirror applied to the separation unit 60. Generally, in dichroic mirrors that reflect a predetermined light and transmit other light at the separation surface, it is relatively easy to increase the reflectivity of the predetermined light, but it is relatively difficult to increase the transmittance of other light, and some of this other light is reflected at the separation surface.

[0096] For example, if a dichroic mirror is used in the separation unit 60 to transmit the measurement light 39, and the measurement light 39 that has passed through the dichroic mirror is allowed to proceed into the measurement optical path, the laser beam 37 is reflected well at the separation surface. On the other hand, a portion of the measurement light 39 is reflected without being transmitted by the dichroic mirror. In other words, the intensity of the measurement light 39 that proceeds into the measurement optical path after passing through the separation unit 60 is reduced.

[0097] Conversely, if a dichroic mirror is used in the separation unit 60 to reflect the measurement light 39, and the measurement light 39 reflected by the dichroic mirror is allowed to proceed into the measurement optical path, the measurement light 39 is well reflected at the separation surface and proceeds into the measurement optical path with little loss of intensity. On the other hand, a portion of the laser beam 37 is reflected by the dichroic mirror without being transmitted. In other words, because a portion of the laser beam 37 also proceeds into the measurement optical path, the purity of the measurement light 39 becomes relatively low.

[0098] Therefore, if greater importance is placed on the high intensity of the measurement light 39 separated in the separation unit 60, it is preferable to use the dichroic mirror 62 described above in the separation unit 60. That is, it is preferable that the measurement light 39 is reflected at the separation surface 64 and the laser beam 37 is transmitted through it.

[0099] In the measuring device 46 according to this embodiment, the laser beam 37 and the measuring light 39 proceed to the separation unit 60 in a state where they are brought closer to parallel light by the first lens unit 54. As a result, the laser beam 37 and the measuring light 39 are well separated at the separation surface of the dichroic mirror in the separation unit 60, that is, the separation characteristics are enhanced. Therefore, in this case, the measuring light 39 that proceeds to the measuring light path can achieve high intensity that could not be achieved in conventional configurations while ensuring the necessary purity. Furthermore, as described later, if the second lens unit 72 is an achromatic lens, the influence of the laser beam 37 mixed into the measuring light path can be ignored.

[0100] On the other hand, if higher purity of the measurement light 39 separated in the separation unit 60 is to be prioritized, it is preferable to use a dichroic mirror in the separation unit 60 that transmits the measurement light 39 and reflects the laser beam 37 at the separation surface.

[0101] In the measuring device 46 according to this embodiment, the laser beam 37 and the measuring light 39 proceed to the separation unit 60 in a state where they are brought closer to parallel light by the first lens unit 54. As a result, the laser beam 37 and the measuring light 39 are well separated at the separation surface of the dichroic mirror in the separation unit 60, that is, the separation characteristics are enhanced. Therefore, in this case, it is easy to obtain extremely high purity of the measuring light 39 that proceeds to the measuring light path, while ensuring the necessary intensity, which was not possible with conventional configurations.

[0102] The measuring device 46 is equipped with a beam damper 70 at the end of the separated optical path 68. In the separation section 60, the laser beam 37 that has passed through the separation surface 64 is absorbed and processed by the beam damper 70. This prevents the laser beam 37 from becoming ambient light in the measurements performed by the measuring device 46.

[0103] The measuring device 46 includes a second lens section 72 positioned in the measuring optical path 66 and a light receiving unit 76 positioned at the end of the measuring optical path 66. The light receiving unit 76 has a light receiving element 78 that receives the measuring light 39.

[0104] The second lens section 72 has the function of imaging the measurement light 39 reflected by the separation surface 64 of the separation section 60 onto the photodetector 78. Preferably, the second lens section 72 is composed of an achromatic lens. An achromatic lens is realized by combining two concave and convex lenses 74a and 74b made of materials with different refractive indices. More specifically, the achromatic lens is composed of a convex lens 74a with positive power and a concave lens 74b with negative power.

[0105] When an achromatic lens is used in the second lens section 72, chromatic aberration and spherical aberration are corrected so that the measurement light 39 is imaged onto the light receiving unit 76. In particular, it is preferable that the system be configured so that the measurement light 39 (for example, light with a wavelength of 520 nm to 580 nm) is imaged well onto the light receiving unit 76.

[0106] In the measuring device 46 according to this embodiment, the laser beam 37 and the measurement light 39 are well separated in the separation unit 60. However, it is conceivable that a small amount of the laser beam 37 may be mixed in with the measurement light 39 traveling in the measurement light path 66. When the laser beam 37 travels in the measurement light path 66 and reaches the light receiving unit 76, the laser beam 37 may become noise in the reception of the measurement light 39 by the light receiving unit 76, potentially reducing the accuracy of the measurement. Furthermore, the light receiving unit 76 may be damaged by the laser beam 37.

[0107] However, when an achromatic lens corresponding to the wavelength band in which the measurement light 39 has intensity is used in the second lens section 72, light of each wavelength included in the measurement light 39 is similarly imaged on the light receiving unit 76. On the other hand, light of wavelengths not supported by the achromatic lens, such as the laser beam 37, is not properly imaged on the light receiving unit 76. In other words, the effect of chromatic aberration of the measurement light 39 can be eliminated, and problems caused by the laser beam 37 that could not be completely separated from the measurement light 39 by the separation section 60 can be avoided.

[0108] For example, the second lens section 72 should use an achromatic lens that does not image light with a wavelength shorter than 520 nm or light with a wavelength greater than 580 nm onto the light receiving unit 76. In other words, it is preferable to use an achromatic lens that images light with a wavelength from 520 nm to 580 nm onto the light receiving unit 76. In this case, the measurement of the state of the laser beam 37 performed by the light receiving unit 76 can be performed with higher precision.

[0109] The measuring device 46 according to this embodiment includes a light-receiving unit 76 having a light-receiving element 78 that receives measuring light 39. The measuring light 39, separated by the separation unit 60 and traveling along the measuring optical path 66, is imaged onto the light-receiving element 78 of the light-receiving unit 76 by the second lens unit 72 and received by the light-receiving element 78. The light-receiving element 78 is, for example, an image sensor such as a CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor).

[0110] For example, the light receiving unit 76 captures the measurement light 39 with the photodetector element 78 and obtains an image. The measurement light 39 is captured in the image. The shape and intensity of the measurement light 39 captured in the image reflect the state of the laser beam 37. Therefore, the state of the laser beam 37 can be determined from the measurement light 39 captured in the image.

[0111] For example, the image captured by the light receiving unit 76 is sent to the controller (control unit) 44 of the laser processing device 2. The controller 44 then evaluates the state of the laser beam 37 based on the received image. For example, the controller 44 determines whether the laser beam 37 is in a state suitable for processing the workpiece 11 by checking whether the intensity distribution (shape, size) of the measuring light 39 captured in the image satisfies predetermined determination conditions.

[0112] Furthermore, for example, the memory unit of the controller 44 may store an image obtained when the laser beam 37 is incident on the measuring device 46 and the light is received by the light receiving element 78 of the light receiving unit 76, in the case when the state of the laser beam 37 is normal. In other words, this image may be stored in the memory unit of the controller 44 as a reference image.

[0113] Furthermore, when measuring the state of the laser beam 37, which is the target of the state measurement, it is preferable that the image obtained by capturing the measurement light 39 with the light receiving unit 76 is compared with a reference image stored in the controller 44. The degree of agreement between the two is then calculated, and the state of the laser beam 37 is measured and evaluated based on this, and the quality of the state of the laser beam 37 is determined.

[0114] The controller 44 displays the determination result on the display unit 40, or notifies the operator of the laser processing device 2 via the notification unit 42. Specifically, the controller 44 notifies the operator that the processing of the workpiece 11 can be properly carried out when the laser beam 37 is in a state suitable for processing the workpiece 11. Alternatively, if the laser beam 37 is not in a state suitable for processing the workpiece 11, the controller 44 warns the operator and prompts them to inspect or correct the laser processing device 2.

[0115] In the laser processing apparatus 2 equipped with the measuring device 46 described above, multiple workpieces 11 are successively laser-processed by the laser irradiation unit 36, and the measuring device 46 is used periodically to measure the state of the laser beam 37.

[0116] In other words, the laser processing apparatus 2 comprises a holding table 28 for holding the workpiece 11, a laser irradiation unit 36 ​​equipped with a laser processing head (concentrator) 38 that can focus a laser beam 37 onto the workpiece 11 held by the holding table 28, and the aforementioned measuring device 46. The laser processing head (concentrator) 38 is capable of focusing the laser beam 37 and irradiating the light-emitting element 48 of the measuring device 46.

[0117] Preferably, the laser processing apparatus 2 further includes a moving unit 6 that moves the focusing point of the light condenser and the light-emitting element 48 of the measuring device 46 relative to each other. As described above, the holding table 28 is movable together with the measuring device 46 by this moving unit 6.

[0118] Next, a measurement method for measuring the shape (state) of the laser beam 37, performed using the measuring device 46 according to this embodiment, will be described. In the measurement method shown in Figure 4(A), the shape, intensity, and other states of the laser beam 37 are measured. This measurement method is performed, for example, by the measuring device 46 incorporated into the laser processing device 2. However, the measurement method for measuring the shape of the laser beam 37 does not need to be performed by the measuring device 46 incorporated into the laser processing device 2. The measuring device 46 may be detachable from the laser processing device 2, or it may be placed outside the laser processing device 2.

[0119] Figure 4(A) is a flowchart showing the flow of each step in a measurement method for measuring the shape (state) of a laser beam 37. This measurement method includes an irradiation step S10 in which the laser beam 37 is irradiated onto a light emitter 48, and a measurement step S20 in which the shape of the laser beam 37 is measured based on the shape of the measurement light 39 imaged on the light receiving element 78 after the irradiation step S10.

[0120] When the laser beam 37, whose shape (state) is to be confirmed, is irradiated onto the light-emitting element 48, a measurement light 39 with a wavelength different from that of the laser beam 37 is generated, as described above. Then, by imaging the generated measurement light 39 onto the photodetector 78 and observing its shape, the shape (state) of the laser beam 37 can be measured.

[0121] Next, the measurement method for measuring the state of the laser beam 37 will be explained in more detail. Figure 3 schematically shows the path of light in the measuring device 46 when this measurement method is performed. Figure 4(B) is a flowchart showing the flow of each step in the measurement method for measuring the state of the laser beam 37. The measurement method shown in Figure 4(B) measures the state of the laser beam 37, such as its shape and intensity. This measurement method is performed, for example, by a measuring device 46 incorporated into the laser processing device 2.

[0122] In this measurement method, the measurement light generation step S21 is performed first. When this measurement method is performed in the laser processing device 2, the moving unit 6 is activated to move the measurement device 46 below the laser processing head (focuser) 38 of the laser irradiation unit 36 ​​when performing the measurement light generation step S21. In addition, the distance between the laser processing head (focuser) 38 and the measurement device 46 (light emitter 48) is adjusted as needed.

[0123] In the measurement light generation step S21, the laser beam 37 is irradiated onto a light-emitting element 48 that emits measurement light 39 with a wavelength different from that of the laser beam 37, thereby generating the measurement light 39. When the laser beam 37 is focused onto the light-emitting element 48, a portion of the laser beam 37 is converted into measurement light 39. As shown in Figure 3, the measurement light 39 and the laser beam 37a that has passed through the light-emitting element 48 proceed to the first lens section 54.

[0124] Next, a first refraction step S22 is performed in which the laser beam 37a and the measurement light 39 that have traveled from the light emitter 48 are refracted by a first lens section 54 having positive power. When the laser beam 37a and the measurement light 39 are refracted by the first lens section 54, they are brought closer to becoming parallel light. After that, the laser beam 37a and the measurement light 39 travel to the separation section 60.

[0125] Next, a separation step S23 is performed in which the laser beam 37a and the measurement light 39 refracted by the first lens section 54 are separated by the separation section 60, the measurement light 39 is guided to the measurement optical path 66, and the laser beam 37a is guided to the separation optical path 68.

[0126] When the laser beam 37a and the measuring light 39 are incident on the separation surface 64 of the separation unit 60, the measuring light 39 is reflected by the separation surface 64 and proceeds into the measuring light path 66, and the laser beam 37a passes through the separation surface 64 and proceeds into the separation light path 68.

[0127] Here, the measurement light 39 etc. incident on the separation surface 64 is brought closer to parallel light by the first lens section 54 which has positive power. As a result, the measurement light 39 etc. incident on the separation surface 64 at a uniform angle of incidence at various points on the separation surface 64. Consequently, the measurement light 39 is appropriately reflected by the separation surface 64, while the laser beam 37a is appropriately transmitted through the separation surface 64.

[0128] Alternatively, in separation step S23, when the laser beam 37a and the measuring light 39 are incident on the separation surface 64 of the separation unit 60, the measuring light 39 may pass through the separation surface 64 and proceed into the measuring light path, and the laser beam 37a may be reflected by the separation surface 64 and proceed into the separation light path 68.

[0129] In this case as well, the measurement light 39 etc. incident on the separation surface 64 is brought closer to parallel light by the first lens section 54 which has positive power. As a result, the measurement light 39 etc. is incident on the separation surface 64 at a uniform angle of incidence at various points on the separation surface 64. Consequently, the laser beam 37a is appropriately reflected by the separation surface 64, while the measurement light 39 is appropriately transmitted through the separation surface 64.

[0130] In any case, the measurement light 39 does not travel through the separation optical path 68, and the laser beam 37a does not travel through the measurement optical path 66. The laser beam 37a traveling through the separation optical path 68 is absorbed by the beam damper 70.

[0131] Next, a second refraction step S24 is performed in which the measurement light 39 separated in the separation unit 60 is imaged onto the photodetector 78 by the second lens unit 72 located in the measurement optical path 66. Then, a light receiving step S25 is performed in which the measurement light 39 refracted in the second refraction step S24 is received by the photodetector 78. When the measurement light 39 is received by the photodetector 78, an image of the measurement light 39 is obtained. In other words, a two-dimensional distribution of the intensity of the measurement light 39 is obtained. The obtained image is transmitted to the controller 44 of the laser processing device 2.

[0132] Next, an evaluation step S26 is performed to evaluate the state of the laser beam 37 from the two-dimensional distribution of the measurement light 39 received by the photodetector 78 in the light receiving step S25. The characteristics of the measurement light 39 generated when the laser beam 37, which is the subject of evaluation, is irradiated onto the light-emitting thin film 52 of the light-emitting body 48, reflect the state of the laser beam 37. Therefore, the state of the laser beam 37 can be evaluated from the state of the measurement light 39 received by the photodetector 78.

[0133] For example, the two-dimensional distribution (shape) of the intensity of the measurement light 39 received by the photodetector 78 reflects the intensity distribution (shape) of the laser beam 37 in a plane perpendicular to the direction of propagation of the laser beam 37. Therefore, the intensity distribution of the laser beam 37 in a plane perpendicular to the direction of propagation of the laser beam 37 can be evaluated from the two-dimensional distribution of the intensity of the measurement light 39 received by the photodetector 78.

[0134] In the memory unit of the controller 44 of the laser processing device 2, for example, the two-dimensional distribution (imaging image) of the intensity of the measurement light 39 received by the photodetector 78 of the measuring device 46 when the state of the laser beam 37 is normal is pre-registered as a reference two-dimensional distribution (reference imaging image).

[0135] Then, when measuring the state of the laser beam 37, the laser beam 37 to be measured is irradiated onto the light-emitting thin film 52 of the light-emitting element 48 of the measuring device 46, thereby obtaining a two-dimensional distribution (image) of the intensity of the measurement light 39 received by the photodetector 78. Subsequently, this two-dimensional distribution (image) is compared with a reference two-dimensional distribution (reference image) stored in the memory unit of the controller 44. The state of the laser beam 37 may be measured in this way.

[0136] For example, a predetermined tolerance range is set for the degree of agreement between the two, and it is determined whether or not there is an abnormality in the state of the laser beam 37 based on whether or not the degree of agreement between the two meets this tolerance range. Alternatively, the controller 44 extracts the outer shape of the cross-sectional shape of the laser beam 37 from both, calculates the amount of positional deviation, and determines whether or not there is an abnormality in the state of the laser beam 37 based on whether or not this positional deviation meets the tolerance range.

[0137] If the measuring device 46 confirms that there is an abnormality in the condition of the laser beam 37, the controller 44 will display a warning screen on the display unit 40. Alternatively, the notification unit 42 will warn the operator. For example, if the notification unit 42 is an indicator light (warning light), it will light up or flash the indicator light to notify the operator of the abnormality. If the notification unit is a speaker, it will emit an alarm sound through the speaker.

[0138] In this case, according to the measurement method shown in Figure 4(B), the laser beam 37a does not mix with the measurement light 39 received by the light-receiving element 78 of the light-receiving unit 76, and the laser beam 37a does not reach the light-receiving element 78 of the light-receiving unit 76. Therefore, the light-receiving element 78 is not damaged by the laser beam 37a, and the state of the laser beam 37 can be measured (evaluated) without being affected by the laser beam 37a.

[0139] Furthermore, the measurement light 39 that has traveled to the separation unit 60 is less likely to travel to the separation optical path 68, and instead travels to the measurement optical path 66 with high intensity, where it is received by the photodetector 78. As a result, the photodetector 78 is less affected by the loss of measurement light 39 in the separation unit 60, and can receive the measurement light 39 with a high intensity and high purity that could not be achieved conventionally.

[0140] As described above, according to the measuring device 46 of this embodiment, the state of the laser beam 37 can be appropriately measured by appropriately separating and receiving the measurement light 39 generated when the laser beam 37 irradiates the light-emitting thin film 52 of the light-emitting body 48 from the laser beam 37a.

[0141] In the above embodiment, the case described was one in which the thickness of the light-emitting thin film 52 of the light-emitting body 48 is determined by referring to the depth of focus of the light-emitting lens, which is calculated based on the numerical aperture (NA) of the light-emitting lens provided on the laser processing head 38 and the wavelength of the laser beam 37. For example, the thickness of the light-emitting thin film 52 is set to a value smaller than the depth of focus. However, the present invention is not limited to this embodiment.

[0142] The thickness of the light-emitting thin film 52 of the light-emitting body 48 may significantly exceed the depth of focus of the light-gatherer. In this case, when the laser beam 37 is irradiated onto the light-emitting thin film 52 of the light-emitting body 48, a relatively high-intensity measurement light 39 is generated from the light-emitting body 48. As a result, the intensity of the measurement light 39 received by the photodetector 78 increases, which may allow for more detailed measurements of the state of the laser beam 37.

[0143] Furthermore, the structures, methods, etc., according to the above embodiments can be modified as appropriate without departing from the scope of the objectives of the present invention. [Explanation of Symbols]

[0144] 11. Items to be processed 11a surface 11b Back side 13th Street 15 devices 17 frames 17a aperture 19 seats 2. Laser Processing Equipment 4 base 6 Mobile Units 8 Y-axis movement unit 10 Y-axis guide rail 12 Y-axis moving table 14 Y-axis ball screw 16 Y-axis pulse motor 18 X-axis movement unit 20 X-axis guide rail 22 X-axis moving table 24 X-axis ball screw 26 X-axis pulse motor 28 Retention Table 28a Holding surface 30 clamps 32 Support structure 34 Support Member 35 Laser Oscillator 36 Laser irradiation unit 37,37a laser beam 38 Laser processing heads 39 Measuring light 40 display units 42 Hochi Unit 44 controllers 46 Measuring device 48 Light-emitting body 50 Support substrate 52 Light-emitting thin film 54 First lens section 56a, 56b lenses 58 Spacing adjustment section 60 Separation section 62 Dichroic Mirror 64 Separation plane 66 Measurement optical path 68 Separation optical path 70 Beam Damper 72 Second lens section 74a Convex lens 74b concave lens 76 Light receiving unit 78 Light-receiving element

Claims

1. A measuring device for measuring the state of a laser beam, A light-emitting body that emits measuring light of a wavelength different from the wavelength of the laser beam when irradiated with the laser beam, A light receiving unit having a light receiving element that receives the measurement light, A first lens portion having positive power to refract the laser beam and the measuring light that have traveled from the light-emitting body, A separation unit separates the laser beam and the measuring light refracted by the first lens unit, guides the measuring light to a measuring optical path leading to the photodetector, and guides the laser beam to a separated optical path that does not reach the photodetector, A measuring device comprising: a second lens unit disposed in the measuring optical path and imaging the measuring light separated by the separation unit onto the photoreceiving element.

2. The measuring apparatus according to claim 1, wherein the separation part is a dichroic mirror that reflects the measuring light and transmits the laser beam.

3. The measuring apparatus according to claim 1, wherein the separation part is a dichroic mirror that transmits the measuring light and reflects the laser beam.

4. The measuring device according to any one of claims 1 to 3, further comprising a spacing adjustment unit for adjusting the distance between the focal point of the first lens portion and the light-emitting element.

5. The measuring device according to any one of claims 1 to 3, wherein the first lens portion is a lens made of quartz or calcium fluoride.

6. The measuring device according to any one of claims 1 to 3, wherein the second lens portion includes an achromatic lens.

7. A laser processing apparatus that irradiates an object to be processed with a laser beam, A holding table for holding the object to be processed, A laser irradiation unit equipped with a light-focusing device that can focus the laser beam onto the workpiece held on the holding table, A measuring device according to any one of claims 1 to 3, comprising: The light concentrator is a laser processing device capable of concentrating the laser beam and irradiating the light-emitting element of the measuring device.

8. The laser processing apparatus according to claim 7, further comprising a moving unit for relatively moving the focusing point of the light condenser and the light-emitting element of the measuring device.

9. The laser processing apparatus according to claim 8, wherein the holding table is movable together with the measuring device by the moving unit.

10. A method for measuring the shape of a laser beam using a measuring device according to any one of claims 1 to 3, An irradiation step of irradiating the light-emitting object with the laser beam, A measurement method comprising: an irradiation step followed by a measurement step of measuring the shape of the laser beam based on the shape of the measurement light imaged on the photodetector.

11. A measurement method for measuring the state of a laser beam, A measurement light generation step involves irradiating a light-emitting element that emits measurement light of a wavelength different from the wavelength of the laser beam when irradiated with the laser beam, thereby generating the measurement light; A first refraction step in which the laser beam and the measuring light propagating from the light emitter are refracted by a first lens section having positive power, A separation step involves separating the laser beam and the measuring light refracted by the first lens section in a separation section, guiding the measuring light to a measuring optical path, and guiding the laser beam to a separation optical path. A second refraction step in which the measurement light separated in the separation unit is imaged onto a photodetector by a second lens unit positioned in the measurement optical path, A light receiving step in which the measuring light refracted in the second refraction step is received by the light receiving element, The light receiving step includes an evaluation step in which the state of the laser beam is evaluated from the two-dimensional distribution of the measurement light received by the light receiving element, A measurement method characterized in that the laser beam guided into the separated optical path in the separation step does not reach the photodetector.

Images