Measuring device, measuring method, and processing device

Abstract

This measurement device (1) is a device for measuring the surface roughness of an object (S), and is provided with: an off-axis parabolic mirror element (11) having: a first surface (12); a second surface (13) comprising a concave parabolic mirror surface and positioned on the reverse side of the first surface (12); and a through-hole (14) that connects the first surface (12) and the second surface (13). The off-axis parabolic mirror element (11) is disposed such that inspection laser light (Ld) from the inspection light source (3) travels toward the object (S) from the first surface (12) side through the through-hole (14), regular reflection light (Lr) from the second surface (13) side through the through-hole (14) travels toward the first detection unit (4), and scattered light (Ls) reflected by the second surface (13) travels toward the second detection unit (5).

Description

Technical Field

[0001] This disclosure relates to a measuring device, a measuring method, and a processing apparatus. Background Technology

[0002] In recent years, laser polishing has been known to smooth the surface of an object by irradiating it with a laser. In laser polishing, the surface of the object is smoothed by melting, reconfiguring, or ablating the surface material using a laser. Compared to polishing with other abrasive materials, laser polishing has the advantages of being able to process any area of ​​an object with complex shapes and suppressing changes in the object's shape before and after processing without producing polishing debris. Further development of this technology is anticipated.

[0003] In laser grinding, from the perspective of quality assessment and management, as with traditional abrasive grinding, it is essential to measure the surface roughness of the workpiece during processing. Previously, surface roughness was primarily measured offline using microscopes, but this method suffers from technical problems such as lack of real-time measurement and the need for a large amount of data.

[0004] As a method for measuring the surface condition of an object using light instead of a microscope, a surface defect detection device is described in Patent Document 1, for example. In this conventional detection device, an inspection laser is incident obliquely onto the surface of the object, and a light-receiving element measures the scattered light and reflected light from the surface of the object. Furthermore, defects on the surface of the object are detected based on the ratio of the intensity of the scattered light to the intensity of the reflected light.

[0005] [Existing Technical Documents]

[0006] [Patent Literature]

[0007] Patent Document 1: Japanese Patent Application Publication No. 11-230912 Summary of the Invention

[0008] [The problem the invention aims to solve]

[0009] However, when applying a detection device like that described in Patent Document 1 to measure the surface roughness of an object in laser grinding, fundamental problems arise, such as the anisotropy of scattered light intensity and the decrease in scattered light intensity on smooth surfaces. Regarding the former, in surfaces with directional roughness, like the ground surface, the anisotropy of scattered light may affect the measurement. Regarding the latter, when measuring smooth surfaces, such as near-mirror surfaces, the scattered light intensity becomes weak, and as a result, the signal-to-noise ratio (SNR) of the measurement signal may decrease.

[0010] Furthermore, when applying a detection device like that in Patent Document 1 to real-time surface roughness measurement in a processing apparatus, it is conceivable that the emission of plasma generated on the surface of the object due to the irradiation of the processing laser would become noise in the measurement. Moreover, in a detection device like that in Patent Document 1, since the scattered light is reflected in all directions from the irradiation position of the inspection laser, it is conceivable that the scattered light would be detected as noise by the light-receiving part used for orthogonal reflection.

[0011] This disclosure was made to solve the above-mentioned problems, and its purpose is to provide a measuring device, a measuring method, and a processing apparatus using the same for real-time measurement of the surface roughness of an object in laser grinding processing.

[0012] [Technical means to solve the problem]

[0013] One aspect of the present disclosure is a measuring device for measuring the surface roughness of an object; and includes: an inspection light source that outputs an inspection laser to the surface of the object; a first detection unit that detects the reflected light of the inspection laser from a measurement point on the surface of the object; a second detection unit that detects the scattered light of the inspection laser from a measurement point on the surface of the object; and an off-axis parabolic mirror element having: a first surface; a second surface, which is composed of a concave parabolic mirror and located on the opposite side of the first surface; and a through hole connecting the first surface and the second surface; and the off-axis parabolic mirror element is configured such that the inspection laser from the inspection light source travels towards the object from the first surface side through the through hole, the reflected light from the second surface side travels towards the first detection unit through the through hole, and the scattered light reflected from the second surface travels towards the second detection unit.

[0014] In this measuring device, by arranging an off-axis parabolic mirror element, the detection of reflected light from the first detection unit and scattered light from the second detection unit can be performed simultaneously. Scattered light generated on the surface of the object travels to the second detection unit at a constant solid angle through the concave parabolic mirror, i.e., the second surface of the off-axis parabolic mirror element. Therefore, even when the surface of the object is a polished surface and the scattered light is anisotropic, or when the surface of the object is a smooth surface and the scattered light is weak, the scattered light can be detected in the second detection unit with sufficient intensity. In addition, in this measuring device, the through-hole of the off-axis parabolic mirror element functions as an aperture that allows only reflected light to pass through, which can suppress light other than reflected light from traveling to the first detection unit. Furthermore, by spatially or temporally offsetting the scattered light reflected from the second surface relative to the processing laser, the emission of plasma generated on the surface of the object due to the irradiation of the processing laser and the scattered light can be suppressed from traveling to the second detection unit together. Therefore, this measuring device can be used to perform real-time measurement of the surface roughness of objects in laser grinding processes.

[0015] The measuring device may further include a calculation unit that calculates the surface roughness of the object based on the ratio of the intensity of the reflected light detected by the first detection unit to the intensity of the scattered light detected by the second detection unit. In this case, the influence of output fluctuations of the inspection laser can be eliminated when calculating the surface roughness of the object. Therefore, the measurement accuracy of surface roughness can be improved.

[0016] The off-axis parabolic mirror element can also be configured such that the inspection laser from the inspection light source travels perpendicularly to the surface of the object through a through-hole from the first surface side. When the inspection laser travels at an angle to the surface of the object, it is conceivable that the optical path of the orthographically reflected light would be significantly deflected due to a height shift in the object, and thus fail to reach the first detection unit. By configuring the off-axis parabolic mirror element such that the inspection laser travels perpendicularly to the surface of the object, the optical path of the orthographically reflected light can be maintained even when there is a height shift in the object, thereby ensuring the accuracy of surface roughness measurement.

[0017] The through-hole can also gradually narrow from the first surface side towards the second surface side. This enhances the through-hole's function as an aperture, and more reliably suppresses the propagation of plasma light caused by scattered light or processing laser towards the first detection unit. Therefore, further improvements in the accuracy of surface roughness measurement can be achieved.

[0018] In the measuring device, a focusing lens can be further configured in the optical path of the scattered light between the second surface and the second detection unit. This further increases the detection intensity of the scattered light from the second detection unit, thereby further improving the accuracy of surface roughness measurement.

[0019] In the measuring device, a semi-reflective mirror can be further configured to share a portion of the optical path of the inspection laser between the inspection light source and the first surface, and a portion of the optical path of the orthogonal reflected light between the first surface and the first detection unit. In this case, by sharing a portion of the optical path of the inspection laser and the orthogonal reflected light, miniaturization of the device can be achieved.

[0020] The measuring device may also include an adjustment mechanism that adjusts the positional relationship between the object and the off-axis parabolic mirror element relative to each other in the direction of travel of the inspection laser from the first surface side through the through hole toward the object. This adjustment mechanism facilitates the alignment of the object and the off-axis parabolic mirror element.

[0021] The adjustment mechanism can also be configured such that a holding part of the off-axis parabolic mirror element can be freely moved from the first surface side through a through hole toward the direction of travel of the inspection laser on the object. Therefore, even when measuring objects of different heights, the distance between the off-axis parabolic mirror element and the surface of the object can be easily made to match the focal distance of the concave parabolic mirror, i.e., the second surface of the off-axis parabolic mirror element.

[0022] The adjustment mechanism can also be configured as a stage that holds the object freely movable from the first surface side through a through hole toward the direction of travel of the inspection laser. Therefore, even when measuring objects of different heights, the distance between the off-axis parabolic mirror element and the surface of the object can be easily made to match the focal distance of the concave parabolic mirror, i.e., the second surface of the off-axis parabolic mirror element.

[0023] The first and second detection units can also be composed of single-channel photodiodes. In this case, the information used for roughness measurement is only the intensity signals of the reflected and scattered light. Therefore, compared to roughness measurement based on 2D image processing, the amount of data processed can be reduced, and processing speed can be improved.

[0024] One aspect of the present disclosure discloses a measurement method for measuring the surface roughness of an object; and includes: an output step, which outputs an inspection laser to the surface of the object; and a detection step, which uses a first detection unit to detect the direct reflection of the inspection laser from a measurement point on the surface of the object, and a second detection unit to detect the scattered light of the inspection laser from a measurement point on the surface of the object; and in the output and detection steps, an off-axis parabolic mirror element is used, which has: a first surface; a second surface, which is composed of a concave parabolic mirror and located on the opposite side of the first surface; and a through hole connecting the first surface and the second surface; the off-axis parabolic mirror element is configured such that the inspection laser travels towards the object from the first surface side through the through hole, the direct reflection of the laser from the second surface side through the through hole travels towards the first detection unit, and the scattered light reflected from the second surface travels towards the second detection unit.

[0025] In this measurement method, by configuring an off-axis parabolic mirror element, the detection of reflected light from the first detection unit and scattered light from the second detection unit can be performed simultaneously. Scattered light generated on the surface of the object travels to the second detection unit at a constant solid angle through the concave parabolic mirror, i.e., the second surface of the off-axis parabolic mirror element. Therefore, even when the surface of the object is polished and the scattered light is anisotropic, or when the surface of the object is smooth and the scattered light is weak, the scattered light can be detected in the second detection unit with sufficient intensity. In addition, in this measurement method, the through-hole of the off-axis parabolic mirror element functions as an aperture that allows only reflected light to pass through, which can suppress light other than reflected light from traveling to the first detection unit. Furthermore, by spatially or temporally offsetting the scattered light reflected from the second surface relative to the processing laser, the emission of plasma generated on the surface of the object due to the irradiation of the processing laser and the scattered light can be suppressed from traveling to the second detection unit together. Therefore, this measuring device can be used to perform real-time measurement of the surface roughness of objects in laser grinding processes.

[0026] One aspect of the present disclosure provides a processing apparatus for processing the surface of an object; and includes: a processing light source that outputs a processing laser to the surface of the object; and the aforementioned measuring device. In this processing apparatus, by using the aforementioned measuring device, real-time measurement of the surface roughness of the object during laser grinding processing can be preferably performed.

[0027] The processing apparatus may further include a calculation unit that calculates the surface roughness of the object based on the ratio of the intensity of the reflected light detected by the first detection unit to the intensity of the scattered light detected by the second detection unit. In this case, the influence of output fluctuations of the inspection laser can be eliminated when calculating the surface roughness of the object. Therefore, the measurement accuracy of surface roughness can be improved.

[0028] The processing apparatus may further include a stage that holds the object in a direction that allows it to move freely from the first surface side through a through-hole toward the object in the direction of travel of the inspection laser and in the in-plane direction of the object's surface. In this case, the processing laser and the inspection laser can be scanned onto the object's surface using the stage. Therefore, the surface roughness of the object can be continuously measured along the processing area, improving the workability of the processing.

[0029] On the surface of the object, the irradiation position of the inspection laser can be offset from the irradiation position of the machining laser. At this time, the optical path of the scattered light reflected from the second surface of the off-axis parabolic mirror element and traveling towards the second detection unit can be spatially separated from the optical path of the plasma emitted from the second surface of the off-axis parabolic mirror element and traveling towards the second detection unit. By spatially separating the optical path of the scattered light from the optical path of the plasma emitted from the plasma, the incident light emitted by the plasma onto the second detection unit can be suppressed, and the influence of the plasma emitted from the plasma on the measurement of the surface roughness of the object can be suppressed.

[0030] Alternatively, an aperture can be configured in the optical path of the scattered light between the second surface and the second detection unit to allow only the scattered light to pass through. In this case, since the aperture can block light other than the scattered light, the emission of plasma caused by the processing laser can be suppressed from traveling to the second detection unit. Therefore, real-time measurement of the surface roughness of the object can be performed more effectively.

[0031] The processing apparatus may further include a control unit that controls the processing laser and the inspection laser to irradiate the surface of the object during different output periods, thereby controlling the processing light source and the inspection light source. In this case, since the scattered light reflected from the second surface and directed towards the second detection unit is time-shifted with the emission of the plasma, which is also reflected from the second surface and travels towards the second detection unit, the influence of the plasma emission on the detection of the scattered light by the second detection unit can be suppressed. Therefore, real-time measurement of the surface roughness of the object can be performed more effectively.

[0032] The calculation unit can also calculate the surface roughness of the object based on the ratio of the intensity of the reflected light detected by the first detection unit during the period when the surface of the object is not irradiated by the processing laser to the intensity of the scattered light detected by the second detection unit during the same period. In this case, the influence of plasma emission caused by the processing laser can be eliminated when calculating the surface roughness of the object. Therefore, it is possible to improve the measurement accuracy of surface roughness.

[0033] [The effects of the invention]

[0034] According to this disclosure, real-time measurement of the surface roughness of an object in laser grinding processing can be preferably performed. Attached Figure Description

[0035] Figure 1 A schematic diagram illustrating the configuration of a measuring device according to one embodiment of the present disclosure.

[0036] Figure 2 This is a diagram showing an example of the calibration curve data stored in the calculation unit.

[0037] Figure 3 A diagram showing the structure of an off-axis parabolic mirror element.

[0038] Figure 4 A flowchart illustrating an example of a measurement method according to one embodiment of this disclosure.

[0039] Figure 5 To display the included Figure 1 A schematic diagram illustrating an example of the configuration of a processing device for the measuring apparatus shown.

[0040] Figure 6 To display the included Figure 1 A schematic diagram of another example of the configuration of the processing device shown in the diagram.

[0041] Figure 7 To display Figure 6 The diagram shows the output timing of the processing laser and the inspection laser in the processing device.

[0042] Figure 8 To display the included Figure 1 The diagram shows another example of the configuration of the processing device for the measuring apparatus shown. Detailed Implementation

[0043] Hereinafter, with reference to the accompanying drawings, a preferred embodiment of the measuring device, measuring method, and processing apparatus of this disclosure will be described in detail.

[0044] Figure 1 A schematic diagram illustrating the configuration of a measuring device according to one embodiment of the present disclosure. Figure 1 The measuring device 1 shown is configured as a device for measuring the surface roughness Sa of an object S. The object S is not particularly limited, and can be, for example, various metallic materials such as copper, aluminum, or iron, or semiconductor wafers.

[0045] like Figure 1 As shown, the measuring device 1 comprises a stage 2 for holding the object S, an inspection light source 3 for outputting an inspection laser Ld, a first detection unit 4 for detecting the reflected light Lr of the inspection laser Ld, a second detection unit 5 for detecting the scattered light Ls of the inspection laser Ld, and a calculation unit 6 for calculating the surface roughness of the object S based on the detection results of the reflected light Lr and the scattered light Ls. An off-axis parabolic mirror element 11 is arranged in the optical path of the inspection laser Ld, the reflected light Lr, and the scattered light Ls.

[0046] The stage 2 has a mounting area for placing the object S. The object S is placed on the stage 2 such that the surface Sa, which is the object to be measured, faces the direction of travel of the inspection laser Ld. The stage 2 functions as an adjustment mechanism that adjusts the positional relationship between the object S and the off-axis parabolic mirror element 11 relative to the direction of travel of the inspection laser Ld towards the object S via a through hole 14 from the first surface 12 side of the off-axis parabolic mirror element 11 (described later). In this embodiment, the stage 2 is, for example, a three-axis movable stage. For alignment of the off-axis parabolic mirror element 11 and the object S in the height direction, the stage 2 can move freely in the direction of travel of the inspection laser Ld. Furthermore, for the purpose of scanning the surface Sa of the object S with the measurement point of the inspection laser Ld, the stage 2 can move freely in the in-plane direction of the surface Sa of the object S.

[0047] The inspection light source 3 outputs an inspection laser Ld to the object S. The inspection light source 3 can be, for example, a HeNe laser. The inspection laser Ld is, for example, a CW (Continuous Wave) light. As an example, the wavelength of the inspection laser Ld is 632.8 nm, the output power is 1 mW, and the beam diameter is 500 μm. The inspection laser Ld output from the inspection light source 3 is reflected by the semi-reflecting mirror 7 and travels perpendicularly to the surface Sa of the object S placed on the stage 2. Alternatively, pulsed light can be used instead of CW light as the inspection laser Ld. When using pulsed light, in order to avoid overlap with the plasma emission from the processing point (e.g., the irradiation position Pw of the processing laser Lw described later), it is preferable to set the repetition frequency of the inspection laser Ld to be lower than the repetition frequency of the processing laser Lw.

[0048] The first detection unit 4 detects the ortho-reflected light Lr from the inspection laser Ld at the measurement point on the surface Sa of the object S. The first detection unit 4 generates information representing the detection result of the ortho-reflected light Lr and outputs this information to the calculation unit 6. In this embodiment, the first detection unit 4 is, for example, configured as a single-channel photodetector, and outputs an intensity signal (current value signal) proportional to the detection result of the ortho-reflected light Lr to the calculation unit 6. As the photodetector, for example, a photodiode, avalanche photodiode, photoelectron multiplier tube, etc., can be used.

[0049] Orthographically reflected light Lr is light reflected when the angle of incidence and the angle of reflection are equal relative to the reflecting surface. In this embodiment, the inspection laser Ld is incident perpendicularly on the surface Sa of the object S. Therefore, the orthographically reflected light Lr is light reflected perpendicularly from the irradiation position (measurement point) Pd of the inspection laser Ld on the surface Sa of the object S. The smaller the surface roughness at the measurement point, the greater the intensity of the orthographically reflected light Lr tends to be.

[0050] In this embodiment, the light-receiving surface of the first detection unit 4 is, for example, a rectangle of 3 mm × 3 mm. The size of this light-receiving surface can also be greater than or equal to the opening width on the first surface 12 side or the opening width on the second surface 13 side of the through hole 14 of the off-axis parabolic mirror element 11 described later. In this case, even if the optical axis of the orthogonal reflected light Lr shifts due to vibration or alignment errors during the use of the measuring device 1, it can be ensured that the orthogonal reflected light Lr is incident on the light-receiving surface of the first detection unit 4.

[0051] The second detection unit 5 detects the scattered light Ls from the inspection laser Ld at the measurement point on the surface Sa of the object S. The second detection unit 5 generates information representing the detection result of the scattered light Ls and outputs this information to the calculation unit 6. In this embodiment, the second detection unit 5 is, for example, configured as a single-channel photodetector, and outputs a current value signal proportional to the detection result of the scattered light Ls to the calculation unit 6. Similar to the first detection unit 4, the photodetector can be, for example, a photodiode, avalanche photodiode, photoelectron multiplier tube, etc.

[0052] Scattered light Ls is light reflected over a wide area from the reflecting surface due to its roughness. Scattered light Ls diffuses omnidirectionally from the irradiation point (measurement point) Pd of the inspection laser Ld on the surface Sa of the object S. When the surface Sa of the object S is, for example, a polished surface with directional surface roughness, scattered light Ls can be reflected anisotropically from the measurement point, corresponding to the direction of polishing. The smaller the surface roughness at the measurement point, the smaller the scattered light Ls tends to be; in the case where the surface Sa of the object S is a surface as smooth as a near-mirror, it can become a very weak light.

[0053] In this embodiment, the light-receiving surface of the second detection unit 5 is, for example, a rectangle of 3 mm × 3 mm. The size of this light-receiving surface can also be the same as that formed in the aperture 24 described later (see reference). Figure 5 The opening width of the pinhole (or opening diameter when the pinhole is circular) is greater than or equal to the opening width of the pinhole. In this case, even if the optical axis of the scattered light Ls is deflected due to vibration or alignment error during the use of the measuring device 1, it can be ensured that the scattered light Ls is incident on the light-receiving surface of the second detection unit 5.

[0054] The calculation unit 6 calculates the surface roughness of the object S. The calculation unit 6 is physically composed of a computer, such as one equipped with a processor (CPU, Central Processing Unit) and storage media such as RAM (Random-Access Memory) and ROM (Read-Only Memory). The computer may also be a smartphone or tablet terminal with an integrated display or input unit. The computer may also be a microcomputer or an FPGA (Field-Programmable Gate Array).

[0055] The calculation unit 6 receives detection result information from the first detection unit 4 and the second detection unit 5, respectively, and calculates the surface roughness of the object S based on the ratio of the intensity of the reflected light Lr to the intensity of the scattered light Ls obtained from these detection result information. When calculating the surface roughness based on the ratio of the intensity of the reflected light Lr to the intensity of the scattered light Ls, the calculation unit 6 pre-stores, for example, calibration curve data for each object S.

[0056] Figure 2 This is a graph illustrating an example of calibration curve data stored in the calculation unit. In this example graph, the horizontal axis represents the ratio of the intensity of scattered light to the intensity of reflected light, and the vertical axis represents the surface roughness. In this calibration curve data, for samples of multiple objects with pre-known surface roughness, the calculated ratio of the intensity of scattered light to the intensity of reflected light is plotted, and a fitting function based on the calculated results is generated.

[0057] The calculation unit 6 calculates the surface roughness measurement result at the measurement point on the surface Sa of the object S by referring to the calibration line data and substituting the ratio of the intensity of the reflected light Lr to the intensity of the scattered light Ls into the fitting function. The calculation unit 6 can display the surface roughness measurement result on a display unit such as a display screen, or store the history of the measurement results for each measurement point in the object S in the storage unit.

[0058] Next, the off-axis parabolic mirror element 11 will be described. Figure 3 The diagram shows the configuration of the off-axis parabolic mirror element in a magnified view. The off-axis parabolic mirror element (non-axis parabolic mirror element) 11 is an element that reflects light from the measurement point Pd as parallel light through the parabolic mirror. Here, the off-axis (non-axis) angle is 90°, but this angle can be set to any angle such as 30°, 45°, 60°, etc.

[0059] like Figure 3As shown, the off-axis parabolic mirror element 11 has a first surface 12, a second surface 13 located opposite to the first surface 12, and a through hole 14 connecting the first surface 12 and the second surface 13. The first surface 12 is a flat, non-mirror surface, while the second surface 13 is a concave parabolic mirror surface. Figure 3 In the image, the off-axis parabolic mirror element 11 is shown from the side, but the actual second surface 13 is a three-dimensional concave parabolic mirror. The width of the second surface 13 along the extension direction of the through hole 14 is, for example, 50 mm.

[0060] The through-hole 14 connects the space on the first surface 12 side with the space on the second surface 13 side. The through-hole 14 is, for example, a circular cross-section. Based on the viewpoint that the through-hole 14 functions as an aperture for positively reflected light Lr, it gradually narrows from the first surface 12 side toward the second surface 13 side. With this configuration, the inspection laser Ld can be reliably incident on the through-hole 14 on the first surface 12 side, and the scattered light Ls or the plasma light accompanying the processing can be better removed on the second surface 13 side.

[0061] From the viewpoint that the through-hole 14 functions as an aperture for positively reflected light Lr, the opening width on the first surface 12 side and the opening width on the second surface 13 side of the through-hole 14 are preferably 10 mm or less. Here, the opening on the first surface 12 side of the through-hole 14 is, for example, a circle with a diameter of 8 mm. The opening on the second surface 13 side of the through-hole 14 is, for example, a circle with a diameter of 3 mm. Furthermore, the cross-sectional shape (opening shape) of the through-hole 14 is not limited to a circle, and may also be elliptical, rectangular, triangular, or other polygonal shapes.

[0062] like Figure 1 As shown, the off-axis parabolic mirror element 11 is configured as follows: the inspection laser Ld from the inspection light source 3 travels towards the object S through the through hole 14 from the first surface 12 side; the positively reflected light Lr from the second surface 13 side travels towards the first detection unit 4 through the through hole 14; and the scattered light Ls reflected from the second surface 13 travels towards the second detection unit 5. The scattered light Ls is collimated when reflected by the concave parabolic mirror surface, i.e., the second surface 13, and travels towards the second detection unit 5 as parallel light.

[0063] Furthermore, the off-axis parabolic mirror element 11 is configured such that the focal point of the concave parabolic mirror surface, i.e., the second surface 13, coincides with the measurement point Pd of the inspection laser Ld. The distance from the measurement point Pd to the center of the opening on the second surface 13 side of the through hole 14 of the off-axis parabolic mirror element 11 is, for example, 50 mm. From the viewpoint of preventing damage to the off-axis parabolic mirror element 11 from debris or plasma generated during irradiation of the processing laser Lw, the distance from the measurement point Pd to the center of the opening on the second surface 13 side of the through hole 14 of the off-axis parabolic mirror element 11 is preferably 10 mm or more. From the viewpoint of miniaturizing the measuring device 1 and shortening the optical path length of the inspection laser Ld, the positively reflected light Lr, and the scattered light Ls to prevent signal attenuation, this distance is preferably 100 mm or less.

[0064] In this embodiment, the off-axis parabolic mirror element 11 is configured such that the parabolic mirror formed on the second surface 13 covers a solid angle of approximately 10% relative to the hemisphere defined by the surface Sa of the object S centered at the measurement point Pd. From the viewpoint of obtaining a sufficiently strong scattered light signal in the second detection unit 5, it is preferable that the parabolic mirror covers a solid angle of 5% or more relative to this hemisphere.

[0065] The solid angle covered by the parabolic mirror can be controlled by adjusting the shape of the parabolic mirror formed on the second surface 13 and the distance from the measuring point Pd to the center of the opening on the second surface 13 side of the through hole 14 of the off-axis parabolic mirror element 11. Specifically, the solid angle covered by the parabolic mirror can be increased by increasing the area of ​​the parabolic mirror, bringing the distance from the measuring point Pd to the center of the opening on the second surface 13 side of the through hole 14 of the off-axis parabolic mirror element 11 closer, or by using both.

[0066] By configuring this off-axis parabolic mirror element 11, in this embodiment, as... Figure 1 As shown, the inspection laser Ld, reflected by the semi-reflecting mirror 7, travels perpendicularly to the surface Sa of the object S through the through-hole 14 from the first surface 12 side. The positively reflected light Lr at the measurement point of the inspection laser Ld is coaxial with and opposite to the inspection laser Ld, passing through the through-hole 14 from the second surface 13 side, and after passing through the semi-reflecting mirror 7, it enters the first detection unit 4. Between the semi-reflecting mirror 7 and the surface Sa of the object S, the optical path of the inspection laser Ld traveling towards the object S and the optical path of the positively reflected light Lr from the object S towards the first detection unit 4 are common.

[0067] Although not shown, a condenser lens can be arranged in the optical path of the orthogonal reflected light Lr between the first surface 12 and the first detection unit 4. In this case, the orthogonal reflected light Lr passing through the through hole 14 from the second surface 13 side is incident on the first detection unit 4 in a state of being focused by the condenser lens. For example, multiple condenser lenses can be arranged in the optical path of the orthogonal reflected light Lr between the first surface 12 and the first detection unit 4. Specifically, a first condenser lens aimed at focusing the orthogonal reflected light Lr on the light-receiving surface of the first detection unit 4 can be arranged between the first detection unit 4 and the half-reflector 7, and a second condenser lens aimed at focusing the inspection laser Ld on the surface Sa of the object S can be arranged between the half-reflector 7 and the first surface 12. With this configuration, the focusing of the orthogonal reflected light Lr and the inspection laser Ld can be better implemented by using the first condenser lens and the second condenser lens corresponding to the orthogonal reflected light Lr and the inspection laser Ld, respectively. Alternatively, it can be configured to only have a first condenser lens and a second condenser lens.

[0068] The scattered light Ls at the measurement point of the laser Ld is reflected at the solid angle formed by the concave parabolic mirror, i.e., the second surface 13, and then incident on the second detection unit 5. Figure 1 In this example, a condenser lens 8 is arranged in the optical path of the scattered light Ls between the second surface 13 and the second detection unit 5. The scattered light Ls is collimated by the concave parabolic mirror, i.e., the second surface 13, and is incident as parallel light onto the condenser lens 8, and is incident onto the second detection unit 5 in a state where it is focused by the condenser lens 8.

[0069] In addition, Figure 1 In this example, the off-axis parabolic mirror element 11 is held by the holding part 9. Like the stage 2, the holding part 9 functions as an adjustment mechanism for relative adjustment of the positional relationship between the object S and the off-axis parabolic mirror element 11 in the direction of travel of the inspection laser Ld from the first surface 12 side of the off-axis parabolic mirror element 11 through the through hole 14 toward the object S. For alignment of the off-axis parabolic mirror element 11 with the object S in the height direction, the holding part 9 holds the off-axis parabolic mirror element 11 movably in the direction of travel of the inspection laser Ld from the first surface 12 side through the through hole 14 toward the object S. The holding part 9 may also be configured to hold the off-axis parabolic mirror element 11, the condenser lens 8, and the second detection part 5 together movably in the direction of travel of the inspection laser Ld from the first surface 12 side through the through hole 14 toward the object S while maintaining the positional relationship of these components.

[0070] Next, a measurement method according to one embodiment of the present disclosure will be described. Figure 4 A flowchart illustrating an example of a measurement method according to an embodiment of this disclosure. For example... Figure 4As shown, the measurement method comprises an output step (step S01), a detection step (step S02), and a calculation step (step S03).

[0071] The output step involves outputting an inspection laser Ld to the surface Sa of the object S. The detection step involves the first detection unit 4 detecting the reflected light Lr from the inspection laser Ld at the measurement point on the surface Sa of the object S, and the second detection unit 5 detecting the scattered light Ls from the inspection laser Ld at the measurement point. The calculation step involves calculating the surface roughness of the object S based on the ratio of the intensity of the reflected light Lr detected in the detection step to the intensity of the scattered light Ls detected in the second detection unit 5.

[0072] In both the output and detection steps, the off-axis parabolic mirror element 11 described above is used. In the output step, the inspection laser Ld travels from the first surface 12 side through the through-hole 14 towards the object S. In the detection step, the positively reflected light Lr from the second surface 13 side through the through-hole 14 travels towards the first detection unit 4, and the scattered light Ls reflected from the second surface 13 travels towards the second detection unit 5. In this embodiment, in the output step, while driving the stage 2 in the in-plane direction of the surface Sa of the object S, the surface Sa of the object S is scanned at the measurement point of the inspection laser Ld, and the detection and calculation steps are repeated. Thus, the surface roughness of the desired area of ​​the surface Sa of the object S can be measured.

[0073] Next, a processing apparatus according to one embodiment of the present disclosure will be described. Figure 5 This is a schematic diagram illustrating an example of the configuration of a processing apparatus. Figure 5 The processing apparatus 21A shown is configured to perform laser grinding processing on the surface Sa of an object S and to measure the surface roughness of the object S in the grinding area in real time.

[0074] like Figure 5 As shown, the processing apparatus 21A includes a processing light source 22 and a processing light source 22. Figure 1 The measuring device 1 shown is configured such that a processing light source 22 outputs a processing laser Lw to the surface Sa of the object S. The processing light source 22 can be, for example, a YAG laser. The processing laser Lw is, for example, a pulsed light. As an example, the wavelength of the processing laser Lw is 1064 nm, and the output intensity is 5 GW / cm². 2 The beam diameter is 50 μm and the repetition rate is 300 kHz. Alternatively, CW light can be used as the processing laser Lw. In this case, as an example, a fiber laser (wavelength 1090 nm) with an output power of around 100 W can be used.

[0075] The processing laser Lw, output from the self-processing light source 22, is focused by the condenser lens 23 and travels towards the surface Sa of the object S placed on the stage 2. In the processing apparatus 21A, by moving the stage 2 in the in-plane direction of the surface Sa of the object S, the surface Sa of the object S can be scanned at the irradiation position Pw of the processing laser Lw and the irradiation position Pd of the inspection laser Ld. Thus, laser grinding processing can be performed on the surface Sa of the object S, and the surface roughness of the object S in the grinding area can be measured in real time.

[0076] In this embodiment, firstly, an inspection laser Ld is irradiated at any point on the surface Sa of the object S, and the calculation unit 6 calculates the surface roughness at the measurement point Pd. After calculating the surface roughness at the measurement point Pd, the stage 2 is moved in the in-plane direction, causing the irradiation position Pw of the processing laser Lw to move to the position of the measurement point Pd, and processing is performed at that position. In this way, by simultaneously calculating and processing the surface roughness at different points, production capacity can be improved.

[0077] In the processing apparatus 21A, plasma is generated on the surface Sa of the object S due to irradiation by the processing laser Lw. It is conceivable that the emission Lp of this plasma will travel towards the first detection unit 4 and the second detection unit 5. The emission Lp of the plasma diffuses omnidirectionally from the irradiation position (measurement point) Pw of the processing laser Lw on the surface Sa of the object S. In the processing apparatus 21A, the off-axis parabolic mirror element 11 is positioned in the optical path of the inspection laser Ld, the positively reflected light Lr, and the scattered light Ls. The through-hole 14 of the off-axis parabolic mirror element 11 functions as an aperture that allows only the positively reflected light Lr to pass through the side of the first surface 12, thus suppressing the emission Lp of the plasma from traveling towards the first detection unit 4.

[0078] Furthermore, based on the viewpoint of suppressing the plasma's luminescence Lp from traveling towards the second detection unit 5, in the processing apparatus 21A, the processing laser Lw and the inspection laser Ld incident on the surface Sa of the object S are spatially offset. Figure 5 In the example, the processing laser Lw and the inspection laser Ld are not coaxial. The processing laser Lw travels towards the surface Sa of the object S in a state that is tilted relative to the inspection laser Ld, which travels perpendicularly towards the surface Sa of the object S.

[0079] On the surface Sa of the object S, the irradiation position Pd of the inspection laser Ld is offset from the irradiation position Pw of the processing laser Lw. The spatial offset between the irradiation positions Pd and Pw is preferably such that the irradiation spot of the processing laser Lw and the irradiation spot of the inspection laser Ld on the surface Sa of the object S do not overlap. For example, it is preferable that the irradiation position Pw of the processing laser Lw and the irradiation position Pd of the inspection laser Ld are separated by an interval of approximately twice the diameter of the irradiation spot of the processing laser Lw or the irradiation spot of the inspection laser Ld. As an example, the interval between the irradiation positions Pd and Pw can be set to approximately 1 mm.

[0080] By examining the spatial offset between the irradiation position Pd of laser Ld and the irradiation position Pw of processing laser Lw, such as... Figure 5 As shown, the optical path of the scattered light Ls reflected from the second surface 13 of the off-axis parabolic mirror element 11 and traveling towards the second detection unit 5 can be spatially separated from the optical path of the plasma emission Lp. By spatially separating the optical path of the scattered light Ls from the optical path of the plasma emission Lp, the incident light emission Lp of the plasma onto the second detection unit 5 can be suppressed.

[0081] In addition, in the processing apparatus 21A, such as Figure 5 As shown, an aperture 24 is arranged in the optical path of the scattered light Ls between the second surface 13 and the second detection unit 5. The aperture 24 is, for example, constructed from a pinhole. Figure 5 In this example, the aperture 24 is positioned between the condenser lens 8 and the second detection unit 5. The aperture 24 is configured to allow only the scattered light Ls to pass through, while the second detection unit 5 blocks the emission Lp of the plasma spatially separated from the scattered light Ls. Based on the viewpoint that only the scattered light Ls travels towards the second detection unit 5 through the aperture 24, the width of the pinhole (or the opening diameter when the pinhole is circular) is preferably 1 mm or less. In this embodiment, the pinhole is circular, and its opening diameter is, for example, 0.1 mm.

[0082] As described above, in the measuring apparatus 1 and measuring method of this embodiment, by configuring the off-axis parabolic mirror element 11, the detection of the positively reflected light Lr of the first detection unit 4 and the detection of the scattered light Ls of the second detection unit 5 can be performed simultaneously. The scattered light Ls generated on the surface Sa of the object S travels towards the second detection unit 5 at a constant solid angle through the second surface 13 of the concave parabolic mirror, i.e., the off-axis parabolic mirror element 11. Therefore, even when the surface Sa of the object S is a polished surface and the scattered light Ls is anisotropic, or when the surface Sa of the object S is a smooth surface and the scattered light Ls is weak, the scattered light Ls can be detected in the second detection unit 5 with sufficient intensity.

[0083] Furthermore, in the measuring device 1, the through-hole 14 of the off-axis parabolic mirror element 11 functions as an aperture that allows only the positively reflected light Lr to pass through, thus suppressing light other than the positively reflected light Lr from traveling to the first detection unit 4. Moreover, by spatially or temporally offsetting the scattered light Ls reflected from the second surface 13 relative to the processing laser Lw, the emission Lp of plasma generated on the surface Sa of the object S due to the irradiation of the processing laser Lw can be suppressed from traveling to the second detection unit 5 along with the scattered light. Therefore, in this measuring device 1, real-time measurement of the surface roughness of the object S during laser grinding can be preferably performed.

[0084] The measuring device 1 includes a calculation unit 6, which calculates the surface roughness of the object S based on the ratio of the intensity of the reflected light Lr detected by the first detection unit 4 to the intensity of the scattered light Ls detected by the second detection unit 5. This calculation method eliminates the influence of output fluctuations of the inspection laser Ld when calculating the surface roughness of the object S. Therefore, it is possible to improve the measurement accuracy of surface roughness.

[0085] In the measuring device 1, the off-axis parabolic mirror element 11 is configured such that the inspection laser Ld from the inspection light source 3 travels perpendicularly from the first surface 12 side through the through hole 14 towards the surface Sa of the object S. When the inspection laser Ld travels at an angle towards the surface Sa of the object S, it is conceivable that if the height of the object S is offset, the optical path of the positively reflected light Lr will be significantly deflected and will not travel towards the first detection unit 4. By configuring the off-axis parabolic mirror element 11 so that the inspection laser Ld travels perpendicularly towards the surface Sa of the object S, the optical path of the positively reflected light Lr can be maintained even if the height of the object S is offset, thus ensuring the accuracy of surface roughness measurement.

[0086] In the measuring device 1, the through-hole 14 gradually narrows from the first surface 12 side toward the second surface 13 side. This enhances the function of the through-hole 14 as an aperture, and more reliably suppresses the propagation of plasma light Lp caused by scattered light Ls or processing laser Lw toward the first detection unit 4. Therefore, further improvement in the accuracy of surface roughness measurement can be achieved.

[0087] In the measuring device 1, a condenser lens 8 is arranged in the optical path of the scattered light Ls between the second surface 13 and the second detection unit 5. This further enhances the detection intensity of the scattered light Ls from the second detection unit 5. Therefore, it is possible to further improve the measurement accuracy of surface roughness.

[0088] In the measuring device 1, a semi-reflective mirror 7 is provided to make a portion of the optical path of the inspection laser Ld between the inspection light source 3 and the first surface 12 and the optical path of the positively reflected light Lr between the first surface 12 and the first detection unit 4 common. In this way, by making a portion of the optical path of the inspection laser Ld and the optical path of the positively reflected light Lr common, the device can be miniaturized.

[0089] The measuring device 1, serving as an adjustment mechanism for the relative positional relationship between the object S and the off-axis parabolic mirror element 11, includes a holding part 9 that can be freely moved and held in the direction of travel of the inspection laser Ld from the first surface 12 side through the through hole 14 toward the object S. Therefore, even when measuring objects S at different heights, the distance between the off-axis parabolic mirror element 11 and the surface Sa of the object S can be easily made to match the focal distance of the concave parabolic mirror surface, i.e., the second surface 13 of the off-axis parabolic mirror element 11.

[0090] The measuring device 1, serving as an adjustment mechanism for the relative positional relationship between the object S and the off-axis parabolic mirror element 11, includes a stage 2 that can be freely moved and held by the object S through the through hole 14 towards the direction of travel of the inspection laser Ld on the object S. Therefore, even when measuring objects S at different heights, the distance between the off-axis parabolic mirror element 11 and the surface Sa of the object S can be easily made to match the focal distance of the concave parabolic mirror surface, i.e., the second surface 13 of the off-axis parabolic mirror element 11.

[0091] In the measuring device 1, the first detection unit 4 and the second detection unit 5 can also be composed of single-channel photodetectors. Therefore, the information used for roughness measurement is only the intensity signals (current signals) of the reflected light Lr and the scattered light Ls. Thus, compared to roughness measurement based on 2D image processing, the amount of data processed can be reduced, allowing for faster processing.

[0092] Furthermore, in the processing apparatus 21A, by using the aforementioned measuring device 1, the surface roughness of the object S during laser grinding can be measured in real time more effectively. In the processing apparatus 21A, the surface Sa of the object S can be scanned by the aforementioned stage 2 using the processing laser Lw and the inspection laser Ld. Therefore, the surface roughness of the object S can be continuously measured along the processing area, improving the workability of the processing.

[0093] In the processing apparatus 21A, the irradiation position Pd of the inspection laser Ld on the surface Sa of the object S can also be offset from the irradiation position Pw of the processing laser Lw. This allows the optical path of the scattered light Ls, reflected from the second surface 13 of the off-axis parabolic mirror element 11 and traveling towards the second detection unit 5, to be spatially separated from the optical path of the plasma emission Lp, which is also reflected from the second surface 13 of the off-axis parabolic mirror element 11 and traveling towards the second detection unit 5. By separating the optical path of the scattered light Ls from the optical path of the plasma emission Lp, the incident of the plasma emission Lp onto the second detection unit 5 can be suppressed, and the influence of the plasma emission Lp on the measurement of the surface roughness of the object S can be suppressed.

[0094] In the processing apparatus 21A, an aperture 24 can be configured in the optical path of the scattered light Ls between the second surface 13 and the second detection unit 5 to allow only the scattered light Ls to pass through. In this case, since light other than the scattered light Ls can be blocked by the aperture 24, the emission Lp of plasma caused by the processing laser Lw can be suppressed from traveling to the second detection unit 5. Therefore, real-time measurement of the surface roughness of the object S can be performed more effectively.

[0095] Figure 6 This is a schematic diagram illustrating another example of the configuration of a processing apparatus. Figure 6 The processing apparatus 21B shown is located at a point coaxial with the processing laser Lw and the inspection laser Ld, which are directed toward the object S. Figure 5 The processing apparatus 21A shown is different. Figure 6 In this example, the processing laser Lw output from the self-processing light source 22 is reflected by the dichroic mirror 25 and focused by the condenser lens 23. Subsequently, the processing laser Lw travels from the first surface 12 side through the through hole 14 of the off-axis parabolic mirror element 11 toward the surface Sa of the object S placed on the stage 2.

[0096] The inspection laser Ld, output from the inspection light source 3, is reflected by the semi-reflecting mirror 7, passes through the dichroic mirror 25, and is coaxial with the processing laser Lw. Subsequently, the inspection laser Ld is focused together with the processing laser Lw by the condenser lens 23, and travels from the first surface 12 side through the through-hole 14 of the off-axis parabolic mirror element 11 towards the surface Sa of the object S placed on the stage 2. The positively reflected light Lr from the measurement point of the inspection laser Ld is coaxial with and in opposite directions to the processing laser Lw and the inspection laser Ld, passes through the through-hole 14 from the second surface 13 side, passes through the dichroic mirror 25 and the semi-reflecting mirror 7, and then enters the first detection unit 4.

[0097] In the processing apparatus 21B, the irradiation position Pd of the inspection laser Ld coincides with the irradiation position Pw of the processing laser Lw. However, the processing laser Lw and the inspection laser Ld, which are incident on the surface Sa of the object S, are out of time. Figure 6In the example, the processing apparatus 21B includes a control unit 26, which controls the processing light source 22 and the inspection light source 3 by irradiating the surface Sa of the object S with the processing laser Lw and the inspection laser Ld at different times.

[0098] The control unit 26 is, for example, a mechanical shutter that shapes a CW light inspection laser Ld into a pulse shape. Figure 7 As shown, the inspection laser Ld is shaped such that the pulse width and repetition frequency of the inspection laser Ld are the same as those of the processing laser Lw, and their output periods do not overlap (the pulses of the inspection laser Ld and the processing laser Lw do not overlap). The control unit 26 generates information indicating the output periods of the processing laser Lw and the inspection laser Ld, and outputs it to the calculation unit 6. The calculation unit 6 calculates the surface roughness of the object S based on the ratio of the intensity of the positively reflected light Lr detected by the first detection unit 4 during the period T when the surface Sa of the object S is not irradiated by the processing laser Lw to the intensity of the scattered light Ls detected by the second detection unit 5 during the same period T. Furthermore, the repetition frequencies of the inspection laser Ld and the processing laser Lw can also be different. For example, by making the repetition frequency of the processing laser Lw greater than that of the inspection laser Ld, the inspection laser Ld can be output once for every few outputs of the processing laser Lw (e.g., about 2 to 20 times). Furthermore, the pulse widths of the inspection laser Ld and the processing laser Lw can be different. For example, the processing laser Lw can also be output as a burst pulse with an extremely short pulse width.

[0099] In this processing apparatus 21B, with Figure 5 Similarly, the processing apparatus 21A shown can also better perform real-time measurement of the surface roughness of the object S during laser grinding. Furthermore, in the processing apparatus 21B, because the scattered light Ls reflected from the second surface 13 and directed towards the second detection unit 5 is time-shifted with the emission Lp of the plasma also reflected from the second surface 13 and traveling towards the second detection unit 5, the influence of the plasma emission Lp on the detection of the scattered light Ls of the second detection unit 5 can be suppressed. Therefore, real-time measurement of the surface roughness of the object S can be performed even better.

[0100] In the processing apparatus 21B, the calculation unit 6 calculates the surface roughness of the object S based on the ratio of the intensity of the positively reflected light Lr detected by the first detection unit 4 during the period T during which the surface Sa of the object S is not irradiated by the processing laser Lw to the intensity of the scattered light Ls detected by the second detection unit 5 during the same period T. Therefore, when calculating the surface roughness of the object S, the influence of plasma emission Lp caused by the processing laser Lw can be eliminated, thereby improving the accuracy of surface roughness measurement.

[0101] The optical system in processing apparatus 21B is not limited to the following configurations. Figure 6 The example shown can also be configured in other ways. For instance, the optical path of the positively reflected light Lr from the second surface 13 side through the through hole 14 toward the first detection unit 4 can be separated from the optical path of the processing laser Lw toward the object S. For example, a semi-reflective mirror can be used to separate the optical path of the positively reflected light Lr from the processing laser Lw. In this case, even if the processing laser Lw and the inspection laser Ld are made coaxial, the positively reflected light of the processing laser Lw can be suppressed from traveling toward the first detection unit 4.

[0102] Alternatively, in the processing apparatus 21B, it can be configured such that, instead of a mechanical shutter, the readout timing of the data from the first detection unit 4 and the second detection unit 5 is offset from the irradiation timing of the processing laser Lw. The configuration that offsets the data readout timing from the irradiation timing of the processing laser Lw can also be used in conjunction with a mechanical shutter.

[0103] Figure 8 This is a schematic diagram illustrating another example of the configuration of the processing apparatus. Figure 8 The processing device 21C shown is Figure 6 The difference in the processing apparatus shown is that, in addition to setting the processing laser Lw and the inspection laser Ld, which are directed toward the object S, to be non-coaxial, it is further equipped with... Figure 6 The control unit 26 is shown. Figure 8 In the example, with the processing laser Lw output from the self-processing light source 22 and the inspection laser Ld output from the self-inspection light source 3 spatially offset, the laser travels from the first surface 12 side through the through hole 14 of the off-axis parabolic mirror element 11 towards the surface Sa of the object S placed on the stage 2. The spatial offset here is related to... Figure 5 Similarly, the preferred method is to measure the offset of the degree to which the irradiation spot of the processing laser Lw and the irradiation spot of the inspection laser Ld do not overlap on the surface Sa of the object S.

[0104] According to this processing device 21C, and Figure 5 Similarly, the emission Lp of the plasma spatially separated from the scattered light Ls can be blocked by the aperture 24 near the second detection unit 5. Furthermore, with Figure 6 Similarly, the surface roughness of the object S can be calculated based on the ratio of the intensity of the positively reflected light Lr detected by the first detection unit 4 during the period T when the surface Sa of the object S is not irradiated by the processing laser Lw to the intensity of the scattered light Ls detected by the second detection unit 5 during the same period T. Therefore, when calculating the surface roughness of the object S, the influence of the plasma emission Lp caused by the processing laser Lw can be eliminated, thereby improving the accuracy of surface roughness measurement.

[0105] This disclosure is not limited to the embodiments described above. For example, in the embodiments described above, although a single through-hole 14 is provided in the off-axis parabolic mirror element 11, multiple through-holes 14 may also be provided in the off-axis parabolic mirror element 11. In this case, for example, one through-hole 14 may be formed at an angle relative to the normal direction of the first surface 12, and another through-hole 14 may be formed at an angle relative to the normal direction of the first surface 12 on the opposite side of the first through-hole 14. Furthermore, the inspection laser Ld travels from the first surface 12 side to the second surface 13 side through one through-hole 14, and the positively reflected light Lr travels from the second surface 13 side to the first surface 12 side through another through-hole 14. Even with this configuration, as in the embodiments described above, real-time measurement of the surface roughness of the object in laser grinding processing can be preferably performed.

[0106] [Symbol Explanation]

[0107] 1: Measuring device

[0108] 2: Stage (adjustment mechanism)

[0109] 3: Check the light source

[0110] 4: First Inspection Department

[0111] 5: Second Inspection Department

[0112] 6: Calculation Department

[0113] 7: Semi-reflective mirror

[0114] 8: Condensing lens

[0115] 9: Maintenance Department (Adjustment Organization)

[0116] 11: Off-axis parabolic mirror element

[0117] 12: Page 1

[0118] 13: Page 2

[0119] 14: Through hole

[0120] 21A~21C: ​​Processing equipment

[0121] 22: Light source for processing

[0122] 24: Aperture

[0123] Ld: Laser for inspection

[0124] Lw: Laser for processing

[0125] Lr: Directly reflected light

[0126] Ls: Scattered light

[0127] Lp: Emission of plasma

[0128] S: Object

[0129] Sa: Surface

[0130] Pd: The location (measurement point) where the laser is applied.

[0131] Pw: Irradiation position of the laser used for processing

[0132] T: The period during which the surface of the object is not irradiated with the laser used for processing.

Claims

1. A measuring device for measuring the surface roughness of an object. Include: An inspection light source that outputs an inspection laser onto the surface of the object; The first detection unit detects the positive reflection of the inspection laser from measurement points on the surface of the object; The second detection unit detects the scattered light from the inspection laser at the measurement point on the surface of the object; and An off-axis parabolic mirror element includes: a first surface; a second surface, which is formed by a concave parabolic mirror and located opposite to the first surface; and a through hole connecting the first surface and the second surface. The off-axis parabolic mirror element is configured such that: the inspection laser from the inspection light source travels from the first surface side through the through hole toward the object; the positively reflected light from the second surface side through the through hole travels toward the first detection unit; and the scattered light reflected from the second surface travels toward the second detection unit.

2. The measuring device as claimed in claim 1, wherein, It further includes a calculation unit that calculates the surface roughness of the object based on the ratio of the intensity of the positively reflected light detected by the first detection unit to the intensity of the scattered light detected by the second detection unit.

3. The measuring device as described in claim 1 or 2, wherein, The off-axis parabolic mirror element is configured such that the inspection laser from the inspection light source travels perpendicularly to the surface of the object through the through hole from the first surface side.

4. The measuring device according to any one of claims 1 to 3, wherein, The through hole gradually narrows as it moves from the first surface towards the second surface.

5. The measuring device according to any one of claims 1 to 4, wherein, A focusing lens is further provided in the optical path of the scattered light between the second surface and the second detection unit.

6. The measuring device according to any one of claims 1 to 5, wherein, A semi-reflective mirror is further configured to make a portion of the optical path of the inspection laser between the inspection light source and the first surface, and the optical path of the positively reflected light between the first surface and the first detection unit common.

7. The measuring device according to any one of claims 1 to 6, wherein, It includes: an adjustment mechanism that adjusts the positional relationship between the object and the off-axis parabolic mirror element relative to each other in the direction of travel of the inspection laser from the first surface side through the through hole toward the object.

8. The measuring device as claimed in claim 7, wherein, The adjustment mechanism is configured to movably hold the holding portion of the off-axis parabolic mirror element in the direction of travel of the inspection laser from the first surface side through the through hole toward the object.

9. The measuring device as claimed in claim 7, wherein, The adjustment mechanism is configured to hold the object on a stage that can be moved freely from the first surface side through the through hole toward the direction of travel of the inspection laser on the object.

10. The measuring device according to any one of claims 1 to 9, wherein, The first detection unit and the second detection unit are configured using a single-channel photodetector.

11. A measurement method for measuring the surface roughness of an object. Include: The output step involves outputting a laser for inspection onto the surface of the object; and The detection step involves using a first detection unit to detect the reflected light of the inspection laser from the measurement points on the surface of the object, and using a second detection unit to detect the scattered light of the inspection laser from the measurement points on the surface of the object. In the output step and the detection step, An off-axis parabolic mirror element is used, comprising: a first surface; a second surface, which is formed by a concave parabolic mirror and located on the opposite side of the first surface; and a through hole connecting the first surface and the second surface. The off-axis parabolic mirror element is configured such that: the inspection laser travels from the first surface side through the through hole toward the object, the positively reflected light from the second surface side through the through hole travels toward the first detection unit, and the scattered light reflected from the second surface travels toward the second detection unit.

12. A processing apparatus for processing the surface of an object, Include: A processing light source that outputs a processing laser to the surface of the object; and The measuring device as described in any one of claims 1 to 10.

13. The processing apparatus as claimed in claim 12, wherein, It further includes a calculation unit that calculates the surface roughness of the object based on the ratio of the intensity of the positively reflected light detected by the first detection unit to the intensity of the scattered light detected by the second detection unit.

14. The processing apparatus as described in claim 12 or 13, wherein, It further includes a stage that can move freely to hold the object in the direction of travel of the inspection laser toward the object from the first surface side through the through hole and in the in-plane direction of the surface of the object.

15. The processing apparatus according to any one of claims 12 to 14, wherein, On the surface of the object, the irradiation position of the inspection laser is offset from the irradiation position of the processing laser.

16. The processing apparatus as claimed in claim 15, wherein, The optical path of the scattered light between the second surface and the second detection unit is provided with an aperture that allows only the scattered light to pass through.

17. The processing apparatus as claimed in claim 13, wherein, It further includes a control unit that controls the processing light source and the inspection light source such that the processing laser and the inspection laser irradiate the surface of the object during different output periods.

18. The processing apparatus as claimed in claim 17, wherein, The calculation unit calculates the surface roughness of the object based on the ratio of the intensity of the positively reflected light detected by the first detection unit during the period when the processing laser does not irradiate the surface of the object to the intensity of the scattered light detected by the second detection unit during the same period.

Images