Measurement device, measurement method, and processing device

Abstract

This measuring device 1 for measuring the surface roughness of an object S includes an off-axis parabolic mirror element 11 having a first surface 12, a second surface 13 composed of a concave parabolic mirror surface and positioned opposite the first surface 12, and a through-hole 14 connecting the first surface 12 and the second surface 13. The off-axis parabolic mirror element 11 is arranged so that inspection laser light Ld from an inspection light source 3 travels from the first surface 12 side through the through-hole 14 to an object S, specular light Lr passing through the through-hole 14 from the second surface 13 side travels to a first detection part 4, and diffuse light Ls reflected by the second surface 13 travels to a second detection part 5.

Description

Measuring device, measuring method, and processing device

[0001] The present disclosure relates to a measurement device, a measurement method, and a processing device.

[0002] In recent years, laser polishing has become known, in which the surface of an object is smoothed by irradiating it with laser light. In laser polishing, the surface of the object is smoothed by melting and rearranging or ablating the surface material with laser light. Compared to conventional polishing using abrasives, laser polishing has the advantages of being able to process any area of ​​an object with a complex shape, minimizing changes in the shape of the object before and after processing, and not producing polishing debris, and further development of the technology is desired.

[0003] In laser polishing, from the viewpoint of evaluating and managing the processing quality, it is essential to measure the surface roughness of the object during processing, just as in polishing using conventional abrasives. Conventionally, offline measurement using a microscope or the like has been mainly used to measure the surface roughness of the object, but this method has technical issues such as poor real-time measurement and the large amount of data required for measurement.

[0004] As a method for measuring the surface condition of an object using light instead of a microscope, for example, there is a surface defect detection device described in Patent Document 1. In this conventional detection device, an inspection laser beam is incident on the surface of the object at an angle, and scattered light and specularly reflected light from the surface of the object are measured by a light receiving element. Then, 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 specularly reflected light.

[0005] Japanese Patent Application Publication No. 11-230912

[0006] However, when a detection device such as that described in Patent Document 1 is applied to measuring the surface roughness of an object during laser polishing, fundamental issues include anisotropy of scattered light intensity and a decrease in scattered light intensity on smooth surfaces. Regarding the former, on surfaces with directional roughness, such as polished surfaces, the anisotropy of scattered light can affect measurement. Regarding the latter, when measuring a smooth surface such as a mirror-like surface, the scattered light intensity becomes weak, which can reduce the signal-to-noise ratio of the measurement signal.

[0007] Furthermore, when a detection device such as that disclosed in Patent Document 1 is applied to real-time measurement of surface roughness in a processing device, it is conceivable that the light emitted by plasma generated on the surface of the object by irradiation with the processing laser light will become measurement noise. Furthermore, in a detection device such as that disclosed in Patent Document 1, scattered light is reflected in all directions from the irradiation position of the inspection laser light, and therefore the scattered light may be detected as a noise component by a light receiving unit for specular reflection light.

[0008] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a measuring device, a measuring method, and a processing device using the same that are suitable for real-time measurement of the surface roughness of an object during laser polishing processing.

[0009] A measuring device according to 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 inspection laser light toward the surface of the object, a first detection unit that detects specularly reflected light of the inspection laser light from a measurement point on the surface of the object, a second detection unit that detects scattered light of the inspection laser light from the measurement point on the surface of the object, and an off-axis parabolic mirror element having a first surface, a second surface formed by a concave parabolic mirror surface and positioned opposite the first surface, and a through hole connecting the first surface and the second surface, wherein the off-axis parabolic mirror element is positioned so that the inspection laser light from the inspection light source travels from the first surface side through the through hole to the object, the specularly reflected light that passes through the through hole from the second surface side travels to the first detection unit, and the scattered light reflected by the second surface travels to the second detection unit.

[0010] In this measurement device, the arrangement of the off-axis parabolic mirror element allows the first detection unit to detect specularly reflected light and the second detection unit to detect scattered light simultaneously. The scattered light generated on the surface of the object travels to the second detection unit at a fixed solid angle due to the second surface of the off-axis parabolic mirror element, which is a concave parabolic mirror surface. Therefore, even if the surface of the object is polished and the scattered light is anisotropic, or even if the surface of the object is smooth and the scattered light is weak, the scattered light can be detected with sufficient intensity in the second detection unit. Furthermore, in this measurement device, the through-hole of the off-axis parabolic mirror element functions as an aperture that passes only specularly reflected light, preventing light other than specularly reflected light from traveling to the first detection unit. Furthermore, by spatially or temporally shifting the scattered light reflected by the second surface relative to the processing laser beam, the emission of plasma generated on the surface of the object by irradiation with the processing laser beam can be prevented from traveling to the second detection unit along with the scattered light. Therefore, this measuring device can suitably perform real-time measurement of the surface roughness of an object during laser polishing.

[0011] The measuring device may further include a calculation unit that calculates the surface roughness of the object based on the ratio between the intensity of the specularly reflected light detected by the first detection unit and the intensity of the scattered light detected by the second detection unit. In this case, the influence of fluctuations in the output of the inspection laser light can be eliminated when calculating the surface roughness of the object. Therefore, the accuracy of measuring the surface roughness can be improved.

[0012] The off-axis parabolic mirror element may be arranged so that the inspection laser light from the inspection light source travels perpendicular to the surface of the object through the through hole from the first surface side. If the inspection laser light travels obliquely to the surface of the object, it is conceivable that if the height of the object shifts, the optical path of the specularly reflected light will shift significantly and will no longer travel to the first detection unit. By arranging the off-axis parabolic mirror element so that the inspection laser light travels perpendicular to the surface of the object, the optical path of the specularly reflected light is maintained even if the height of the object shifts, thereby ensuring the accuracy of surface roughness measurement.

[0013] The through-hole may be gradually narrowed from the first surface side toward the second surface side. This strengthens the aperture function of the through-hole and more reliably prevents scattered light or plasma light emitted by the processing laser beam from traveling to the first detection unit. This further improves the accuracy of measuring the surface roughness.

[0014] The measurement device may further include a condenser lens disposed in the optical path of the scattered light between the second surface and the second detector, thereby further increasing the intensity of the scattered light detected by the second detector, thereby further improving the accuracy of measuring surface roughness.

[0015] The measurement device may further include a half mirror that shares a part of the optical path of the inspection laser light between the inspection light source and the first surface and a part of the optical path of the specularly reflected light between the first surface and the first detection unit. In this case, by sharing a part of the optical path of the inspection laser light and a part of the optical path of the specularly reflected light, the device can be made smaller.

[0016] The measurement device may have an adjustment mechanism that relatively adjusts the positional relationship between the object and the off-axis parabolic mirror element in the traveling direction of the inspection laser light that passes through the through hole from the first surface side toward the object. Such an adjustment mechanism makes it easy to align the object and the off-axis parabolic mirror element.

[0017] The adjustment mechanism may be configured with a holder that holds the off-axis parabolic mirror element movably in the direction of propagation of the inspection laser light that passes through the through hole from the first surface side toward the object. This makes it possible to easily adjust the distance between the off-axis parabolic mirror element and the surface of the object to the focal length of the second surface of the off-axis parabolic mirror element, which is a concave parabolic mirror surface, even when measuring objects of different heights.

[0018] The adjustment mechanism may be configured with a stage that holds the object so as to be movable in the direction of propagation of the inspection laser light that passes through the through hole from the first surface side toward the object. This makes it possible to easily adjust the distance between the off-axis parabolic mirror element and the surface of the object to the focal length of the second surface of the off-axis parabolic mirror element, which is a concave parabolic mirror surface, even when measuring objects of different heights.

[0019] The first and second detectors may be configured with single-channel photodiodes. In this case, the information used for roughness measurement is only the intensity signals of specularly reflected light and scattered light. Therefore, the amount of data handled can be reduced compared to roughness measurement based on two-dimensional image processing, and processing speed can be increased.

[0020] A measurement method according to one aspect of the present disclosure is a measurement method for measuring the surface roughness of an object, comprising: an output step of outputting inspection laser light onto the surface of the object; and a detection step of detecting specularly reflected light of the inspection laser light from a measurement point on the surface of the object with a first detection unit, and detecting scattered light of the inspection laser light from the measurement point on the surface of the object with a second detection unit. In the output step and the detection step, an off-axis parabolic mirror element is used, which has a first surface, a second surface composed of a concave parabolic mirror surface and positioned opposite the first surface, and a through hole connecting the first surface and the second surface, and the off-axis parabolic mirror element is positioned so that the inspection laser light travels from the first surface side through the through hole to the object, the specularly reflected light that passes through the through hole from the second surface side travels to the first detection unit, and the scattered light reflected by the second surface travels to the second detection unit.

[0021] In this measurement method, the arrangement of the off-axis parabolic mirror element allows the first detection unit to detect specularly reflected light and the second detection unit to detect scattered light simultaneously. The scattered light generated on the surface of the object travels to the second detection unit at a constant solid angle due to the second surface of the off-axis parabolic mirror element, which is a concave parabolic mirror surface. Therefore, even if the surface of the object is polished and the scattered light is anisotropic, or even if the surface of the object is smooth and the scattered light is weak, the scattered light can be detected with sufficient intensity in the second detection unit. Furthermore, in this measurement method, the through-hole of the off-axis parabolic mirror element functions as an aperture that passes only specularly reflected light, preventing light other than specularly reflected light from traveling to the first detection unit. Furthermore, by spatially or temporally shifting the scattered light reflected by the second surface relative to the processing laser beam, it is possible to prevent plasma emission generated on the surface of the object by irradiation with the processing laser beam from traveling to the second detection unit together with the scattered light. Therefore, this measuring device can suitably perform real-time measurement of the surface roughness of an object during laser polishing.

[0022] According to one aspect of the present disclosure, a processing apparatus for processing a surface of an object includes a processing light source that outputs a processing laser beam to the surface of the object, and the measuring device. By using the measuring device, this processing apparatus can suitably perform real-time measurement of the surface roughness of the object during laser polishing.

[0023] The processing device may further include a calculation unit that calculates the surface roughness of the object based on the ratio between the intensity of the specularly reflected light detected by the first detection unit and the intensity of the scattered light detected by the second detection unit. In this case, the influence of fluctuations in the output of the inspection laser light can be eliminated when calculating the surface roughness of the object. Therefore, the accuracy of measuring the surface roughness can be improved.

[0024] The processing apparatus may further include a stage that holds the object so as to be movable in the direction of propagation of the inspection laser light directed from the first surface side through the through hole toward the object and in the in-plane direction of the surface of the object. In this case, the stage allows the processing laser light and the inspection laser light to scan the surface of the object. Therefore, the surface roughness of the object can be measured continuously along the processing area, improving processing workability.

[0025] On the surface of the object, the irradiation position of the inspection laser light may be shifted from the irradiation position of the processing laser light. In this case, the optical path of the scattered light reflected by the second surface of the off-axis parabolic mirror element and traveling to the second detection unit can be spatially separated from the optical path of the plasma light emission reflected by the second surface of the off-axis parabolic mirror element and traveling to the second detection unit. By spatially separating the optical paths of the scattered light and the plasma light emission, the plasma light emission is prevented from entering the second detection unit, and the plasma light emission can be prevented from affecting the measurement of the surface roughness of the object.

[0026] An aperture that passes only the scattered light may be disposed in the optical path of the scattered light between the second surface and the second detector. In this case, the aperture can block light other than the scattered light, thereby preventing plasma emission caused by the processing laser beam from progressing to the second detector. This allows for more suitable real-time measurement of the surface roughness of the object.

[0027] The processing apparatus may further include a control unit that controls the processing light source and the inspection light source so that the processing laser beam and the inspection laser beam are irradiated onto the surface of the object for different output periods. In this case, the scattered light reflected by the second surface and proceeding to the second detection unit and the plasma emission reflected by the second surface and proceeding to the second detection unit are time-delayed, thereby preventing the plasma emission from affecting the detection of the scattered light by the second detection unit. Therefore, real-time measurement of the surface roughness of the object can be more effectively performed.

[0028] The calculation unit may calculate the surface roughness of the object based on the ratio between the intensity of the specularly reflected light detected by the first detection unit during a period when the processing laser beam is not irradiated onto the surface of the object and the intensity of the scattered light detected by the second detection unit during the same period. In this case, the influence of plasma light emission caused by the processing laser beam can be eliminated when calculating the surface roughness of the object. Therefore, the accuracy of measuring the surface roughness can be improved.

[0029] According to the present disclosure, real-time measurement of the surface roughness of an object during laser polishing can be suitably performed.

[0030] 6 is a schematic diagram showing a configuration of a measurement device according to an embodiment of the present disclosure. FIG. 7 is a diagram showing an example of calibration curve data stored in a calculation unit. FIG. 8 is an enlarged view showing the configuration of an off-axis parabolic mirror element. FIG. 9 is a flowchart showing an example of a measurement method according to an embodiment of the present disclosure. FIG. 10 is a schematic diagram showing an example of the configuration of a processing device including the measurement device shown in FIG. 1. FIG. 11 is a schematic diagram showing another example of the configuration of a processing device including the measurement device shown in FIG. 1. FIG. 12 is a diagram showing output timings of a processing laser beam and an inspection laser beam in the processing device shown in FIG. 6. FIG. 7 is a schematic diagram showing yet another example of the configuration of a processing device including the measurement device shown in FIG.

[0031] Hereinafter, preferred embodiments of a measuring device, a measuring method, and a processing device according to one aspect of the present disclosure will be described in detail with reference to the drawings.

[0032] Fig. 1 is a schematic diagram showing the configuration of a measurement device according to an embodiment of the present disclosure. The measurement device 1 shown in Fig. 1 is configured as a device that measures the roughness of a surface Sa of an object S. The object S is not particularly limited, but may be, for example, various metal materials such as copper, aluminum, or iron, or a semiconductor wafer.

[0033] 1, the measurement device 1 includes a stage 2 on which an object S is placed, an inspection light source 3 that outputs an inspection laser light Ld, a first detection unit 4 that detects specularly reflected light Lr of the inspection laser light Ld, a second detection unit 5 that detects scattered light Ls of the inspection laser light Ld, and a calculation unit 6 that calculates the surface roughness of the object S based on the detection results of the specularly reflected light Lr and the scattered light Ls. An off-axis parabolic mirror element 11 is arranged in the optical paths of the inspection laser light Ld, the specularly reflected light Lr, and the scattered light Ls.

[0034] The stage 2 has a mounting area on which the object S is placed. The object S is placed on the stage 2 so that the surface Sa to be measured faces the traveling direction of the inspection laser light Ld. The stage 2 functions as an adjustment mechanism that relatively adjusts the positional relationship between the object S and the off-axis parabolic mirror element 11 with respect to the traveling direction of the inspection laser light Ld, which travels from the first surface 12 side of the off-axis parabolic mirror element 11 to the object S through the through hole 14, as described below. In this embodiment, the stage 2 is configured by, for example, a three-axis movable stage. The stage 2 is freely movable in the traveling direction of the inspection laser light Ld to align the height direction of the off-axis parabolic mirror element 11 and the object S. Furthermore, the stage 2 is freely movable in the in-plane direction of the surface Sa of the object S for the purpose of scanning the measurement points of the inspection laser light Ld on the surface Sa of the object S.

[0035] The inspection light source 3 outputs an inspection laser light Ld to the object S. As the inspection light source 3, for example, a HeNe laser or the like can be used. The inspection laser light Ld is, for example, a CW light. As an example, the inspection laser light Ld has a wavelength of 632.8 nm, an output power of 1 mW, and a beam diameter of 500 μm. The inspection laser light Ld output from the inspection light source 3 is reflected by the half mirror 7 and travels perpendicular to the surface Sa of the object S placed on the stage 2. Note that, instead of CW light, pulsed light can also be used as the inspection laser light Ld. When pulsed light is used, it is preferable to set the repetition frequency of the inspection laser light Ld lower than the repetition frequency of the processing laser light Lw so as not to overlap with plasma emission from the processing point (for example, an irradiation position Pw of the processing laser light Lw described below).

[0036] The first detection unit 4 detects specularly reflected light Lr of the inspection laser light Ld from a measurement point on the surface Sa of the object S. The first detection unit 4 generates information indicating the detection result of the specularly reflected light Lr and outputs the information to the calculation unit 6. In this embodiment, the first detection unit 4 is configured by, for example, a single-channel photodetector, and outputs an intensity signal (current value signal) having a magnitude proportional to the detection result of the specularly reflected light Lr to the calculation unit 6. As the photodetector, for example, a photodiode, an avalanche photodiode, a photomultiplier tube, or the like can be used.

[0037] The specularly reflected light Lr is light reflected from a reflecting surface at an angle of incidence and an angle of reflection that are equal. In this embodiment, the inspection laser light Ld is perpendicularly incident on the surface Sa of the object S. Therefore, the specularly reflected light Lr is light that is perpendicularly reflected from the irradiation position (measurement point) Pd of the inspection laser light Ld on the surface Sa of the object S. The intensity of the specularly reflected light Lr tends to increase as the surface roughness of the measurement point decreases.

[0038] In this embodiment, the light-receiving surface of the first detecting unit 4 has a rectangular shape measuring, for example, 3 mm x 3 mm. The size of the light-receiving surface may be equal to or greater than 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 specularly reflected light Lr is shifted due to vibrations or alignment errors during use of the measurement device 1, the incidence of the specularly reflected light Lr on the light-receiving surface of the first detecting unit 4 can be ensured.

[0039] The second detection unit 5 detects scattered light Ls of the inspection laser light Ld from a measurement point on the surface Sa of the object S. The second detection unit 5 generates information indicating the detection result of the scattered light Ls and outputs the information to the calculation unit 6. In this embodiment, the second detection unit 5 is configured by, for example, a single-channel photodetector, and outputs a current value signal having a magnitude proportional to the detection result of the scattered light Ls to the calculation unit 6. As with the first detection unit 4, the photodetector may be, for example, a photodiode, an avalanche photodiode, a photomultiplier tube, or the like.

[0040] The scattered light Ls is light that is reflected over a wide range from the reflecting surface due to the surface roughness of the reflecting surface. The scattered light Ls is diffused in all directions starting from the irradiation position (measurement point) Pd of the surface Sa of the object S with the inspection laser light Ld. If the surface Sa of the object S is, for example, a polished surface and the surface roughness has directionality, the scattered light Ls may be reflected from the measurement point with anisotropy according to the direction of polishing. The scattered light Ls tends to become smaller as the surface roughness of the measurement point decreases, and if the surface Sa of the object S is a smooth surface close to a mirror finish, the scattered light Ls may be weak in intensity.

[0041] In this embodiment, the light-receiving surface of the second detection unit 5 has a rectangular shape measuring, for example, 3 mm x 3 mm. The size of the light-receiving surface may be equal to or greater than the opening width (or the opening diameter if the pinhole is circular) of the pinhole formed in the aperture 24 (see FIG. 5 ), which will be described later. In this case, even if the optical axis of the scattered light Ls is shifted due to vibrations or alignment errors during use of the measurement device 1, it is possible to ensure that the scattered light Ls is incident on the light-receiving surface of the second detection unit 5.

[0042] The calculation unit 6 calculates the surface roughness of the target object S. The calculation unit 6 is physically configured by a computer including, for example, a processor such as a CPU, and storage media such as a RAM and a ROM. The computer may be a smartphone or tablet terminal that is integrated with a display unit and an input unit. The computer may also be configured by a microcomputer, an FPGA (Field-Programmable Gate Array), or the like.

[0043] The calculation unit 6 receives the detection result information from the first detection unit 4 and the detection result information from the second detection unit 5, and calculates the surface roughness of the object S based on the ratio between the intensity of the specular reflection light Lr and the intensity of the scattered light Ls obtained from the detection result information. The calculation unit 6 stores, in advance, for example, calibration curve data for each object S, in order to calculate the surface roughness based on the ratio between the intensity of the specular reflection light Lr and the intensity of the scattered light Ls.

[0044] 2 is a diagram showing an example of calibration curve data stored in the calculation unit. In the example shown in the figure, the horizontal axis represents the ratio of the intensity of scattered light to the intensity of specularly reflected light, and the vertical axis represents surface roughness. In this calibration curve data, the calculation results of the ratio of the intensity of scattered light to the intensity of specularly reflected light for multiple object samples with known surface roughness are plotted, and a fitting function is generated based on the calculation results.

[0045] The calculation unit 6 refers to the calibration curve data and substitutes the ratio between the intensity of the specularly reflected light Lr and the intensity of the scattered light Ls into a fitting function to calculate the measurement results of the surface roughness at the measurement points on the surface Sa of the object S. The calculation unit 6 may display the measurement results of the surface roughness on a display or other display unit, or may store a history of the measurement results for each measurement point on the object S in a storage unit.

[0046] Next, the off-axis parabolic mirror element 11 will be described. FIG. 3 is an enlarged view showing the configuration of the off-axis parabolic mirror element. The off-axis parabolic mirror element (off-axis parabolic mirror element) 11 is an element that reflects light from measurement point Pd as parallel light using a parabolic mirror surface. Here, the off-axis (off-axis) angle is 90°, but this angle can be set to any angle, such as 30°, 45°, or 60°.

[0047] As shown in Fig. 3, the off-axis parabolic mirror element 11 has a first surface 12, a second surface 13 located opposite 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. While Fig. 3 shows the off-axis parabolic mirror element 11 from the side, the second surface 13 is actually a three-dimensional concave parabolic mirror surface. The width of the second surface 13 along the extension direction of the through-hole 14 is, for example, 50 mm.

[0048] The through hole 14 communicates between the space on the first surface 12 side and the space on the second surface 13 side. The through hole 14 has, for example, a circular cross section. The through hole 14 gradually narrows from the first surface 12 side toward the second surface 13 side in order to function as an aperture for the specularly reflected light Lr. With this configuration, the inspection laser light Ld can be reliably incident on the through hole 14 on the first surface 12 side, while the scattered light Ls and plasma light associated with processing can be suitably cut off on the second surface 13 side.

[0049] From the viewpoint of allowing the through-hole 14 to function as an aperture for the specularly reflected light Lr, the opening width of the through-hole 14 on the first surface 12 side and the opening width on the second surface 13 side are preferably 10 mm or less. Here, the opening of the through-hole 14 on the first surface 12 side is, for example, a circle with a diameter of 8 mm. The opening of the through-hole 14 on the second surface 13 side is, for example, a circle with a diameter of 3 mm. Note that the cross-sectional shape (opening shape) of the through-hole 14 is not limited to a circle, and may be an ellipse, a rectangle, a triangle, or any other polygonal shape.

[0050] 1, the off-axis parabolic mirror element 11 is arranged so that the inspection laser light Ld from the inspection light source 3 travels from the first surface 12 side through the through-hole 14 to the object S, the specularly reflected light Lr that passes through the through-hole 14 from the second surface 13 side travels to the first detecting unit 4, and the scattered light Ls reflected by the second surface 13 travels to the second detecting unit 5. The scattered light Ls is collimated when reflected by the second surface 13, which is a concave parabolic mirror surface, and travels to the second detecting unit 5 in the form of parallel light.

[0051] The off-axis parabolic mirror element 11 is also positioned so that the focal point of the second surface 13, which is a concave parabolic mirror surface, coincides with the measurement point Pd of the inspection laser light Ld. The distance from the measurement point Pd to the center of the opening of the through-hole 14 of the off-axis parabolic mirror element 11 on the second surface 13 side is, for example, 50 mm. From the viewpoint of preventing damage to the off-axis parabolic mirror element 11 due to debris and plasma generated during irradiation with the processing laser light Lw, it is preferable that the distance from the measurement point Pd to the center of the opening of the through-hole 14 of the off-axis parabolic mirror element 11 on the second surface 13 side be 10 mm or more. From the viewpoint of miniaturizing the measurement device 1 and from the viewpoint of shortening the optical path lengths of the inspection laser light Ld, the specularly reflected light Lr, and the scattered light Ls to prevent attenuation of the signal amount, it is preferable that this distance be 100 mm or less.

[0052] In this embodiment, the off-axis parabolic mirror element 11 is arranged so that the parabolic mirror surface formed on the second surface 13 covers a solid angle of about 10% with respect to a hemisphere centered on the measurement point Pd and defined by the surface Sa of the object S. From the viewpoint of acquiring a scattered light signal of sufficient intensity in the second detection unit 5, it is preferable that the parabolic mirror surface covers a solid angle of 5% or more with respect to the hemisphere.

[0053] The solid angle covered by the parabolic mirror surface can be controlled by adjusting the shape of the parabolic mirror surface formed on the second surface 13 and 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. Specifically, the solid angle covered by the parabolic mirror surface can be increased by increasing the area of ​​the parabolic mirror surface, shortening 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, or by using both of these together.

[0054] 1 , in this embodiment, by disposing the off-axis parabolic mirror element 11 in this manner, the inspection laser light Ld reflected by the half mirror 7 travels perpendicularly to the surface Sa of the object S through the through-hole 14 from the first surface 12 side. The specularly reflected light Lr at the measurement point of the inspection laser light Ld travels through the through-hole 14 from the second surface 13 side coaxially with and in the opposite direction to the inspection laser light Ld, passes through the half mirror 7, and then enters the first detection unit 4. Between the half mirror 7 and the surface Sa of the object S, the optical path of the inspection laser light Ld traveling toward the object S and the optical path of the specularly reflected light Lr traveling from the object S toward the first detection unit 4 are shared.

[0055] Although not shown, a condenser lens may be arranged in the optical path of the specularly reflected light Lr between the first surface 12 and the first detection unit 4. In this case, the specularly reflected light Lr that has passed through the through hole 14 from the second surface 13 side is focused by the condenser lens and then enters the first detection unit 4. For example, a plurality of condenser lenses may be arranged in the optical path of the specularly reflected light Lr between the first surface 12 and the first detection unit 4. Specifically, a first condenser lens for focusing the specularly reflected light Lr at the light-receiving surface of the first detection unit 4 may be arranged between the first detection unit 4 and the half mirror 7, and a second condenser lens for focusing the inspection laser light Ld at the surface Sa of the target S may be arranged between the half mirror 7 and the first surface 12. With this configuration, the specularly reflected light Lr and the inspection laser light Ld can be more suitably focused by the first condenser lens and the second condenser lens corresponding to the specularly reflected light Lr and the inspection laser light Ld, respectively. It is also possible to adopt a configuration in which only one of the first condenser lens and the second condenser lens is disposed.

[0056] Scattered light Ls at the measurement point of the inspection laser light Ld is reflected by the second surface 13, which is a concave parabolic mirror surface, at a solid angle formed by the second surface 13, and is incident on the second detection unit 5. In the example of Fig. 1, a condenser lens 8 is disposed 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 second surface 13, which is a concave parabolic mirror surface, and is incident on the condenser lens 8 as parallel light. The scattered light Ls is then incident on the second detection unit 5 in a state where it is condensed by the condenser lens 8.

[0057] 1 , the off-axis parabolic mirror element 11 is held by a holding unit 9. Similar to the stage 2, the holding unit 9 functions as an adjustment mechanism that relatively adjusts the positional relationship between the object S and the off-axis parabolic mirror element 11 in the traveling direction of the inspection laser light Ld traveling from the first surface 12 side of the off-axis parabolic mirror element 11 through the through hole 14 toward the object S. The holding unit 9 holds the off-axis parabolic mirror element 11 movably in the traveling direction of the inspection laser light Ld traveling from the first surface 12 side toward the object S through the through hole 14, in order to align the height direction of the off-axis parabolic mirror element 11 and the object S. The holding unit 9 may be configured to hold the off-axis parabolic mirror element 11, the condenser lens 8, and the second detection unit 5 movably together in the traveling direction of the inspection laser light Ld traveling from the first surface 12 side toward the object S through the through hole 14, while maintaining the positional relationship among them.

[0058] Next, a measurement method according to an embodiment of the present disclosure will be described. Fig. 4 is a flowchart showing an example of the measurement method according to an embodiment of the present disclosure. As shown in Fig. 4, this measurement method includes an output step (step S01), a detection step (step S02), and a calculation step (step S03).

[0059] The output step is a step of outputting the inspection laser light Ld to the surface Sa of the object S. The detection step is a step of detecting the specularly reflected light Lr of the inspection laser light Ld from a measurement point on the surface Sa of the object S with the first detection unit 4, and detecting the scattered light Ls of the inspection laser light Ld from the measurement point with the second detection unit 5. The calculation step is a step of calculating the surface roughness of the object S based on the ratio between the intensity of the specularly reflected light Lr detected in the detection step and the intensity of the scattered light Ls detected by the second detection unit 5.

[0060] The output step and the detection step use the off-axis parabolic mirror element 11 described above. In the output step, the inspection laser light Ld is caused to travel from the first surface 12 side through the through-hole 14 to the object S. In the detection step, the specularly reflected light Lr that has passed through the through-hole 14 from the second surface 13 side is caused to travel to the first detection unit 4, and the scattered light Ls reflected by the second surface 13 is caused to travel to the second detection unit 5. In this embodiment, in the output step, the stage 2 is driven in the in-plane direction of the surface Sa of the object S, and the detection step and the calculation step are repeatedly performed while the measurement point of the inspection laser light Ld is scanned across the surface Sa of the object S. This makes it possible to measure the surface roughness of a desired region of the surface Sa of the object S.

[0061] Next, a processing apparatus according to an embodiment of the present disclosure will be described. Fig. 5 is a schematic diagram showing an example of the configuration of the processing apparatus. The processing apparatus 21A shown in Fig. 5 is configured to perform laser polishing on the surface Sa of the object S and to perform real-time measurement of the surface roughness of the object S in the polishing region.

[0062] As shown in Fig. 5, the processing device 21A includes a processing light source 22 and the measuring device 1 shown in Fig. 1. The processing light source 22 outputs a processing laser light Lw to the surface Sa of the object S. As the processing light source 22, for example, a YAG laser or the like can be used. The processing laser light Lw is, for example, pulsed light. As an example, the processing laser light Lw has a wavelength of 1064 nm and an output intensity of 5 GW / cm. ２ The beam diameter is 50 μm and the repetition frequency is 300 kHz. Note that CW light may be used as the processing laser light Lw. In this case, for example, a fiber laser (wavelength 1090 nm) with an output power of about 100 W may be used.

[0063] The processing laser light Lw output from the processing light source 22 is focused by the focusing lens 23 and travels toward the surface Sa of the object S placed on the stage 2. In the processing device 21A, the stage 2 is moved in the in-plane direction of the surface Sa of the object S, so that the irradiation position Pw of the processing laser light Lw and the irradiation position Pd of the inspection laser light Ld can be scanned over the surface Sa of the object S. This makes it possible to perform laser polishing on the surface Sa of the object S and to measure the surface roughness of the object S in the polishing region in real time.

[0064] In this embodiment, first, an arbitrary point on the surface Sa of the object S is irradiated with the inspection laser light Ld, and the surface roughness at the measurement point Pd is calculated by the calculation unit 6. After calculating the surface roughness at the measurement point Pd, the stage 2 is moved in the in-plane direction to move the irradiation position Pw of the processing laser light Lw to the position of the measurement point Pd, and processing of that position is performed. In this way, by simultaneously calculating the surface roughness and processing different points, throughput is improved.

[0065] In the processing device 21A, it is considered that plasma is generated on the surface Sa of the target object S by irradiation with the processing laser light Lw, and the plasma light Lp travels to the first detection unit 4 and the second detection unit 5. The plasma light Lp diffuses in all directions from the irradiation position (measurement point) Pw of the processing laser light Lw on the surface Sa of the target object S as the starting point. To cope with such plasma light Lp, the processing device 21A has the above-mentioned off-axis parabolic mirror element 11 disposed in the optical paths of the inspection laser light Ld, the specularly 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 specularly reflected light Lr to pass toward the first surface 12, thereby suppressing the plasma light Lp from traveling to the first detection unit 4.

[0066] Furthermore, from the viewpoint of suppressing the progression of the plasma light emission Lp toward the second detection unit 5, in the processing device 21A, the processing laser light Lw and the inspection laser light Ld that are incident on the surface Sa of the object S are spatially shifted. In the example of Fig. 5, the processing laser light Lw and the inspection laser light Ld are non-coaxial, and the processing laser light Lw proceeds toward the surface Sa of the object S at an angle relative to the inspection laser light Ld that proceeds perpendicularly toward the surface Sa of the object S.

[0067] On the surface Sa of the object S, the irradiation position Pd of the inspection laser light Ld is shifted from the irradiation position Pw of the processing laser light Lw. The spatial shift amount between the irradiation positions Pd, Pw is preferably such that the irradiation spot of the processing laser light Lw and the irradiation spot of the inspection laser light Ld do not overlap each other on the surface Sa of the object S. For example, it is preferable that the irradiation position Pw of the processing laser light Lw and the irradiation position Pd of the inspection laser light Ld are separated by a distance that is about twice the diameter of the irradiation spot of the processing laser light Lw or the diameter of the irradiation spot of the inspection laser light Ld. As an example, the distance between the irradiation positions Pd, Pw can be about 1 mm.

[0068] 5 , the optical path of the scattered light Ls reflected by the second surface 13 of the off-axis parabolic mirror element 11 and traveling to the second detection unit 5 can be spatially separated from the optical path of the plasma light emission Lp. The spatial separation of the optical path of the scattered light Ls from the optical path of the plasma light emission Lp prevents the plasma light emission Lp from entering the second detection unit 5.

[0069] Furthermore, in the processing apparatus 21A, as shown in FIG. 5 , an aperture 24 is disposed in the optical path of the scattered light Ls between the second surface 13 and the second detection unit 5. The aperture 24 is configured, for example, as a pinhole. In the example of FIG. 5 , the aperture 24 is disposed between the condenser lens 8 and the second detection unit 5. The aperture 24 is disposed to pass only the scattered light Ls and blocks the plasma light emission Lp, which is spatially separated from the scattered light Ls, before reaching the second detection unit 5. From the viewpoint of allowing only the scattered light Ls to travel to the second detection unit 5 through the aperture 24, the width of the pinhole (opening diameter if 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.

[0070] As described above, in the measurement device 1 and measurement method according to this embodiment, the arrangement of the off-axis parabolic mirror element 11 allows the first detection unit 4 to detect the specularly reflected light Lr and the second detection unit 5 to detect the scattered light Ls simultaneously. The scattered light Ls generated on the surface Sa of the object S travels to the second detection unit 5 at a certain solid angle due to the second surface 13 of the off-axis parabolic mirror element 11, which is a concave parabolic mirror surface. Therefore, even if the surface Sa of the object S is a polished surface and the scattered light Ls is anisotropic, or even if the surface Sa of the object S is a smooth surface and the scattered light Ls is weak, the second detection unit 5 can detect the scattered light Ls with sufficient intensity.

[0071] Furthermore, in the measurement device 1, the through hole 14 of the off-axis parabolic mirror element 11 functions as an aperture that passes only the specularly reflected light Lr, and can prevent light other than the specularly reflected light Lr from proceeding to the first detection unit 4, and by spatially or temporally shifting the scattered light Ls reflected by the second surface 13 relative to the processing laser light Lw, it is possible to prevent the plasma light emission Lp generated on the surface Sa of the object S by irradiation with the processing laser light Lw from proceeding together with the scattered light to the second detection unit 5. Therefore, the measurement device 1 can suitably perform real-time measurement of the surface roughness of the object S during laser polishing.

[0072] The measurement device 1 includes a calculation unit 6 that calculates the surface roughness of the object S based on the ratio between the intensity of the specularly reflected light Lr detected by the first detection unit 4 and the intensity of the scattered light Ls detected by the second detection unit 5. This calculation method can eliminate the influence of fluctuations in the output of the inspection laser light Ld when calculating the surface roughness of the object S. Therefore, the measurement accuracy of the surface roughness can be improved.

[0073] In the measurement device 1, the off-axis parabolic mirror element 11 is arranged so that the inspection laser light Ld from the inspection light source 3 travels from the first surface 12 side through the through hole 14 perpendicular to the surface Sa of the object S. When the inspection laser light Ld travels obliquely to the surface Sa of the object S, it is conceivable that if the height of the object S is shifted, the optical path of the specularly reflected light Lr will be significantly shifted and will no longer travel to the first detection unit 4. By arranging the off-axis parabolic mirror element 11 so that the inspection laser light Ld travels perpendicular to the surface Sa of the object S, the optical path of the specularly reflected light Lr is maintained even if the height of the object S is shifted, thereby ensuring the measurement accuracy of the surface roughness.

[0074] In the measurement device 1, the through-hole 14 gradually narrows from the first surface 12 side toward the second surface 13 side. This strengthens the function of the through-hole 14 as an aperture, and more reliably prevents the scattered light Ls or the plasma light emission Lp caused by the processing laser light Lw from traveling to the first detection unit 4. This further improves the accuracy of measuring the surface roughness.

[0075] In the measurement device 1, a condenser lens 8 is disposed in the optical path of the scattered light Ls between the second surface 13 and the second detection unit 5. This makes it possible to further increase the detection intensity of the scattered light Ls at the second detection unit 5. Therefore, the measurement accuracy of the surface roughness is further improved.

[0076] In the measurement device 1, a half mirror 7 is disposed to share a part of the optical path of the inspection laser light Ld between the inspection light source 3 and the first surface 12, and a part of the optical path of the specularly reflected light Lr between the first surface 12 and the first detection unit 4. In this way, by sharing a part of the optical path of the inspection laser light Ld and the optical path of the specularly reflected light Lr, the device can be made smaller.

[0077] The measurement device 1 is provided with a holding unit 9, which serves as an adjustment mechanism for relatively adjusting the positional relationship between the object S and the off-axis parabolic mirror element 11, and which holds the off-axis parabolic mirror element 11 movably in the traveling direction of the inspection laser light Ld that passes from the first surface 12 side through the through hole 14 toward the object S. This makes it possible to easily adjust the distance between the off-axis parabolic mirror element 11 and the surface Sa of the object S to the focal length of the second surface 13 of the off-axis parabolic mirror element 11, which is a concave parabolic mirror surface, even when measuring objects S of different heights.

[0078] The measurement device 1 is provided with a stage 2, which serves as an adjustment mechanism for relatively adjusting the positional relationship between the object S and the off-axis parabolic mirror element 11, and which holds the object S movably in the direction of propagation of the inspection laser light Ld that passes from the first surface 12 side through the through hole 14 toward the object S. This makes it possible to easily adjust the distance between the off-axis parabolic mirror element 11 and the surface Sa of the object S to the focal length of the second surface 13 of the off-axis parabolic mirror element 11, which is a concave parabolic mirror surface, even when measuring objects S of different heights.

[0079] In the measurement device 1, the first detection unit 4 and the second detection unit 5 are configured as single-channel photodetectors. As a result, the only information used for roughness measurement is the intensity signals (current value signals) of the specularly reflected light Lr and the scattered light Ls. Therefore, the amount of data handled can be reduced compared to when roughness measurement is performed based on two-dimensional image processing, and processing speed can be increased.

[0080] Furthermore, the processing device 21A can suitably perform real-time measurement of the surface roughness of the object S during laser polishing by using the above-described measuring device 1. In the processing device 21A, the above-described stage 2 can scan the processing laser beam Lw and the inspection laser beam Ld over the surface Sa of the object S. Therefore, measurement of the surface roughness of the object S can be performed continuously along the processing area, improving the workability of processing.

[0081] In the processing device 21A, the irradiation position Pd of the inspection laser beam Ld is shifted from the irradiation position Pw of the processing laser beam Lw on the surface Sa of the object S. This makes it possible to spatially separate the optical path of the scattered light Ls that is reflected by the second surface 13 of the off-axis parabolic mirror element 11 and travels to the second detection unit 5, and the optical path of the plasma light emission Lp that is also reflected by the second surface 13 of the off-axis parabolic mirror element 11 and travels to the second detection unit 5. Because the optical paths of the scattered light Ls and the plasma light emission Lp are spatially separated, the plasma light emission Lp is prevented from entering the second detection unit 5, and the plasma light emission Lp can be prevented from affecting the measurement of the surface roughness of the object S.

[0082] In the processing device 21A, an aperture 24 that passes only the scattered light Ls is disposed in the optical path of the scattered light Ls between the second surface 13 and the second detection unit 5. In this case, light other than the scattered light Ls can be blocked by the aperture 24, and therefore, the plasma light emission Lp caused by the processing laser light Lw can be prevented from proceeding to the second detection unit 5. Therefore, real-time measurement of the surface roughness of the target object S can be more suitably performed.

[0083] Fig. 6 is a schematic diagram showing another example of the configuration of a processing apparatus. The processing apparatus 21B shown in Fig. 6 differs from the processing apparatus 21A shown in Fig. 5 in that the processing laser light Lw and the inspection laser light Ld directed toward the target object S are coaxial. In the example of Fig. 6, the processing laser light Lw output from the processing light source 22 is reflected by a dichroic mirror 25 and condensed by a condenser lens 23. Thereafter, the processing laser light Lw passes through the through hole 14 of the off-axis parabolic mirror element 11 from the first surface 12 side and proceeds toward the surface Sa of the target object S placed on the stage 2.

[0084] The inspection laser light Ld output from the inspection light source 3 is reflected by the half mirror 7, passes through the dichroic mirror 25, and becomes coaxial with the processing laser light Lw. Thereafter, the inspection laser light Ld is condensed together with the processing laser light Lw by the condenser lens 23, passes through the through hole 14 of the off-axis parabolic mirror element 11 from the first surface 12 side, and proceeds toward the surface Sa of the object S placed on the stage 2. The specularly reflected light Lr at the measurement point of the inspection laser light Ld passes through the through hole 14 from the second surface 13 side coaxially with and in the opposite direction to the processing laser light Lw and the inspection laser light Ld, passes through the dichroic mirror 25 and the half mirror 7, and then enters the first detection unit 4.

[0085] In the processing device 21B, the irradiation position Pd of the inspection laser light Ld and the irradiation position Pw of the processing laser light Lw are aligned, while the processing laser light Lw and the inspection laser light Ld incident on the surface Sa of the object S are shifted in time. In the example of Fig. 6, the processing device 21B includes a control unit 26 that controls the processing light source 22 and the inspection light source 3 so that the processing laser light Lw and the inspection laser light Ld are irradiated onto the surface Sa of the object S for different periods.

[0086] The control unit 26 is configured with a mechanical shutter that shapes the inspection laser light Ld, which is, for example, a CW light, into a pulsed form. As shown in FIG. 7 , for example, the control unit 26 shapes the inspection laser light Ld so that the inspection laser light Ld has the same pulse width and repetition frequency as the processing laser light Lw and so that their output periods do not overlap (so that the pulses of the inspection laser light Ld and the processing laser light Lw do not overlap). The control unit 26 generates information indicating the output periods of the processing laser light Lw and the inspection laser light 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 between the intensity of the specular reflection light Lr detected by the first detection unit 4 during a period T when the processing laser light Lw is not irradiated onto the surface Sa of the object S and the intensity of the scattered light Ls detected by the second detection unit 5 during the same period T. The repetition frequencies of the inspection laser light Ld and the processing laser light Lw may be different from each other. For example, by making the repetition frequency of the processing laser light Lw higher than the repetition frequency of the inspection laser light Ld, the inspection laser light Ld may be output once for each multiple (e.g., 2 to 20) outputs of the processing laser light Lw. The pulse widths of the inspection laser light Ld and the processing laser light Lw may be different from each other. For example, the processing laser light Lw may be output as a burst pulse having an extremely short pulse width.

[0087] 5 , this processing apparatus 21B can also suitably perform real-time measurement of the surface roughness of the object S during laser polishing. Furthermore, in the processing apparatus 21B, there is a time lag between the scattered light Ls reflected by the second surface 13 and proceeding toward the second detection unit 5 and the plasma light emission Lp also reflected by the second surface 13 and proceeding toward the second detection unit 5, so that it is possible to prevent the plasma light emission Lp from affecting the detection of the scattered light Ls by the second detection unit 5. Therefore, it is possible to more suitably perform real-time measurement of the surface roughness of the object S.

[0088] In the processing device 21B, the calculation unit 6 calculates the surface roughness of the object S based on the ratio between the intensity of the specularly reflected light Lr detected by the first detection unit 4 during a period T in which the processing laser light Lw is not irradiated onto the surface Sa of the object S and the intensity of the scattered light Ls detected by the second detection unit 5 during the same period T. This makes it possible to eliminate the influence of the plasma light emission Lp caused by the processing laser light Lw when calculating the surface roughness of the object S, thereby improving the measurement accuracy of the surface roughness.

[0089] The configuration of the optical system in the processing device 21B is not limited to the example shown in Fig. 6, and other configurations may be employed. For example, a configuration may be adopted in which the optical path of the specularly reflected light Lr traveling from the second surface 13 side through the through hole 14 toward the first detection unit 4 is separated from the optical path of the processing laser light Lw traveling toward the target object S. A half mirror, for example, can be used to separate the optical path of the specularly reflected light Lr from the processing laser light Lw. In this case, even if the processing laser light Lw and the inspection laser light Ld are coaxial, the specularly reflected light of the processing laser light Lw can be prevented from traveling toward the first detection unit 4.

[0090] Furthermore, in the processing device 21B, instead of the mechanical shutter, a mode may be adopted in which the timing of reading out data from the first detection unit 4 and the second detection unit 5 is shifted from the timing of irradiating the processing laser beam Lw. The mode in which the timing of reading out data is shifted from the timing of irradiating the processing laser beam Lw may be used in combination with the mechanical shutter.

[0091] 8 is a schematic diagram showing another example of the configuration of the processing apparatus. The processing apparatus 21C shown in FIG. 8 differs from the processing apparatus shown in FIG. 6 in that the processing laser light Lw and the inspection laser light Ld directed toward the object S are non-coaxial and further include the control unit 26 shown in FIG. 6. In the example of FIG. 8, the processing laser light Lw output from the processing light source 22 and the inspection laser light Ld output from the inspection light source 3 pass through the through hole 14 of the off-axis parabolic mirror element 11 from the first surface 12 side in a spatially shifted state and proceed toward the surface Sa of the object S placed on the stage 2. The amount of spatial shift here is preferably such that the irradiation spots of the processing laser light Lw and the irradiation spots of the inspection laser light Ld do not overlap each other on the surface Sa of the object S, as in the case of FIG. 5.

[0092] 5, such a processing apparatus 21C can block the plasma light emission Lp spatially separated from the scattered light Ls by the aperture 24 before the second detection unit 5. Also, similar to the case of Fig. 6, the surface roughness of the object S can be calculated based on the ratio between the intensity of the specular reflection light Lr detected by the first detection unit 4 during a period T in which the processing laser light Lw is not irradiated onto the surface Sa of the object S and 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 light emission Lp caused by the processing laser light Lw can be eliminated, thereby improving the measurement accuracy of the surface roughness.

[0093] The present disclosure is not limited to the above-described embodiment. For example, in the above-described embodiment, a single through hole 14 is provided in the off-axis parabolic mirror element 11. However, multiple through holes 14 may be provided in the off-axis parabolic mirror element 11. In this case, for example, one through hole 14 is formed at an angle with respect to the normal direction of the first surface 12, and the other through hole 14 is formed at an angle on the opposite side to the one through hole 14 with respect to the normal direction of the first surface 12. Then, the inspection laser light Ld is propagated from the first surface 12 side to the second surface 13 side through one through hole 14, and the specularly reflected light Lr is propagated from the second surface 13 side to the first surface 12 side through the other through hole 14. Even in this configuration, as in the above-described embodiment, real-time measurement of the surface roughness of an object during laser polishing can be preferably performed.

[0094] 1...measuring device, 2...stage (adjustment mechanism), 3...inspection light source, 4...first detection unit, 5...second detection unit, 6...calculation unit, 7...half mirror, 8...condensing lens, 9...holding unit (adjustment mechanism), 11...off-axis parabolic mirror element, 12...first surface, 13...second surface, 14...through hole, 21A to 21C...processing device, 22...processing light source, 24...aperture, Ld...inspection laser light, Lw...processing laser light, Lr...specularly reflected light, Ls...scattered light, Lp...plasma emission, S...object, Sa...surface, Pd...irradiation position of inspection laser light (measurement point), Pw...irradiation position of processing laser light, T...period when the processing laser light is not irradiated onto the surface of the object.

Claims

1. A measuring device for measuring the surface roughness of an object, comprising: an inspection light source that outputs an inspection laser beam to the surface of the object; a first detection unit that detects specular reflection light of the inspection laser light from a measurement point on the surface of the object; a second detection unit that detects scattered light of the inspection laser light from the measurement point on the surface of the object; an off-axis parabolic mirror element having a first surface, a second surface configured with a concave parabolic mirror surface and positioned opposite the first surface, and a through hole connecting the first surface and the second surface; The off-axis parabolic mirror element is arranged so that the inspection laser light from the inspection light source travels from the first surface side through the through hole to the object, the specularly reflected light that passes through the through hole from the second surface side travels to the first detection unit, and the scattered light reflected at the second surface travels to the second detection unit.

2. 2. The measuring device according to claim 1, further comprising a calculation unit that calculates the surface roughness of the object based on a ratio between the intensity of the specularly reflected light detected by the first detection unit and the intensity of the scattered light detected by the second detection unit.

3. 3. The measurement device according to claim 1, wherein the off-axis parabolic mirror element is arranged so that the inspection laser light from the inspection light source travels perpendicular to the surface of the object from the first surface side through the through hole.

4. The measurement device according to claim 1 , wherein the through-hole gradually narrows from the first surface side toward the second surface side.

5. The measurement device according to claim 1 or 2, further comprising a condenser lens disposed in an optical path of the scattered light between the second surface and the second detection unit.

6. 3. The measurement device according to claim 1, further comprising a half mirror that shares a part of the optical path of the inspection laser light between the inspection light source and the first surface and a part of the optical path of the specularly reflected light between the first surface and the first detection unit.

7. 3. The measurement device according to claim 1, further comprising an adjustment mechanism that relatively adjusts the positional relationship between the object and the off-axis parabolic mirror element in the propagation direction of the inspection laser light that passes through the through hole from the first surface side toward the object.

8. 8. The measurement device according to claim 7, wherein the adjustment mechanism is configured by a holding unit that holds the off-axis parabolic mirror element movably in the propagation direction of the inspection laser light that passes through the through hole from the first surface side toward the object.

9. 8. The measuring device according to claim 7, wherein the adjustment mechanism is configured by a stage that holds the object so as to be movable in the direction of propagation of the inspection laser light that passes through the through hole and heads toward the object from the first surface side.

10. 3. The measuring device according to claim 1, wherein the first detecting unit and the second detecting unit are configured by single-channel photodetectors.

11. A measurement method for measuring the surface roughness of an object, comprising: an output step of outputting an inspection laser beam to the surface of the object; a detecting step of detecting specularly reflected light of the inspection laser light from a measurement point on the surface of the object with a first detecting unit and detecting scattered light of the inspection laser light from the measurement point on the surface of the object with a second detecting unit, In the outputting step and the detecting step, an off-axis parabolic mirror element having a first surface, a second surface configured by a concave parabolic mirror surface and positioned opposite the first surface, and a through hole connecting the first surface and the second surface; A measurement method in which the off-axis parabolic mirror element is positioned so that the inspection laser light travels from the first surface side through the through hole to the object, the specularly reflected light that passes through the through hole from the second surface side travels to the first detection unit, and the scattered light reflected at the second surface travels to the second detection unit.

12. A processing device for processing a surface of an object, a processing light source that outputs processing laser light to the surface of the object; A processing device comprising the measuring device according to claim 1.

13. The processing apparatus according to claim 12, further comprising a calculation unit that calculates the surface roughness of the object based on a ratio between the intensity of the specularly reflected light detected by the first detection unit and the intensity of the scattered light detected by the second detection unit.

14. The processing apparatus according to claim 12, further comprising a stage that holds the object so that it can be moved freely in the direction of propagation of the inspection laser light that passes through the through hole from the first surface side toward the object and in the in-plane direction of the surface of the object.

15. 13. The processing device according to claim 12, wherein the irradiation position of the inspection laser light on the surface of the object is shifted from the irradiation position of the processing laser light.

16. The processing apparatus according to claim 15 , wherein an aperture that passes only the scattered light is disposed in an optical path of the scattered light between the second surface and the second detection unit.

17. The processing device according to claim 13 , further comprising a control unit that controls the processing light source and the inspection light source so that the processing laser light and the inspection laser light are irradiated onto the surface of the object for output periods different from each other.

18. 18. The processing device according to claim 17, wherein the calculation unit calculates the surface roughness of the object based on a ratio between the intensity of the specular reflected light detected by the first detection unit during a period when the processing laser light is not irradiated onto the surface of the object and the intensity of the scattered light detected by the second detection unit during the same period.