Surface roughness measuring device and surface roughness measuring method

Abstract

The objective is to provide a surface roughness measuring device and a surface roughness measuring method that can measure the surface roughness of an object being measured even when it is moving at high speed. [Solution] The system comprises a laser light source that irradiates the surface of an object to be measured with laser light at an angle of 5 to 45 degrees, a light receiving sensor that receives reflected laser light reflected at a measurement point on the surface of the object to be measured, and a laser light roughness calculation means that calculates a laser light roughness value, which is the surface roughness value of the object to be measured, from the amount of reflected laser light received by the light receiving sensor, wherein the laser light roughness calculation means calculates the laser light roughness value from the distribution of the magnitude of the amount of reflected laser light at a single measurement point.

Description

Technical Field

[0001] The present invention relates to a surface roughness measuring apparatus and a surface roughness measuring method for measuring the surface roughness of a measurement object having a surface capable of reflecting laser light.

Background Art

[0002] Conventionally, various surface roughness measuring apparatuses and surface roughness measuring methods for measuring the surface roughness of steel plates, bars, and the like have been proposed. A conventional surface roughness measuring apparatus is a contact type using a stylus. For example, the detector and the surface roughness measuring machine of Patent Document 1 have a measuring element having a stylus at its tip that contacts the measuring surface of the measurement object, a holding unit that holds the measuring element swingably by a rotation fulcrum, a sensor that detects the displacement of the measuring element, a main body unit that houses the holding unit and the sensor and from which the measuring element extends from an end, an illumination optical fiber that transmits illumination light incident from a first incident end and emits the illumination light from a first emission end disposed at the end of the main body unit, and an image transmission optical fiber that transmits subject light incident from a second incident end and emits the subject light from a second emission end, and is characterized by including these.

[0003] Further, the roughness measuring machine of Patent Document 2 includes a stylus unit having a stylus that can protrude and retract from a through hole of a skid and moves along the work surface, and a stylus displacement detection unit that detects the displacement of the stylus, and a drive unit that moves the stylus unit forward and backward in the drive shaft direction. Further, the roughness measuring machine includes a height detector provided on the side opposite to the front end surface of the main body housing portion with the skid interposed therebetween so as to detect the height of an object in a direction parallel to the measurement axis Z. When the height detector detects an object at the same height as the height of the main body support leg in the measurement axis direction, the drive unit automatically starts driving and the stylus unit performs tracing measurement of the work surface.

Prior Art Documents

Patent Documents

[0004] [Patent Document 1] Japanese Patent Publication No. 2018-169325 [Patent Document 2] Japanese Patent Publication No. 2021-42999 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] However, conventional surface roughness measuring instruments use a stylus for measurement, and because they are contact-based, they cannot measure the surface roughness of an object in manufacturing processes where the object is moving at high speed.

[0006] The present invention has been made in view of these circumstances, and aims to provide a surface roughness measuring device and a surface roughness measuring method that can measure the surface roughness of an object being measured even when it is moving at high speed. [Means for solving the problem]

[0007] The surface roughness measuring device according to claim 1 is characterized by comprising: a laser light source that irradiates the surface of an object to be measured with laser light at an angle of 5 to 45 degrees with the surface of the object to be measured; a light receiving sensor that receives reflected laser light reflected at a measurement point which is the surface of the object to be measured; and a laser light roughness calculation means that calculates a laser light roughness value, which is the value of the surface roughness of the object to be measured, from the amount of reflected laser light received by the light receiving sensor.

[0008] The surface roughness measuring device according to claim 2 is characterized in that, in addition to the configuration of claim 1, the laser roughness calculation means calculates a laser roughness value from laser light intensity distribution data, which is the distribution of the magnitude of the amount of reflected laser light at one measurement point.

[0009] The surface roughness measuring device according to claim 3 is characterized in that, in addition to the configuration of claim 2, the laser roughness value calculated by the laser roughness calculation means is a variance value calculated from laser light intensity distribution data.

[0010] The surface roughness measuring device according to claim 4 is characterized in that, in addition to the configuration of any one of claims 1 to 3, it comprises a roughness value conversion means that converts the laser roughness value calculated by the laser roughness calculation means into a converted roughness value equivalent to that obtained when measured by a method other than laser light, based on the correlation with the roughness value measured by a method other than laser light.

[0011] The surface roughness measuring device according to claim 5 is characterized by comprising: a laser light source that irradiates the surface of an object to be measured with laser light at an angle of 5 to 45 degrees with the surface of the object to be measured; a light receiving sensor that receives reflected laser light reflected at a measurement point which is the surface of the object to be measured; and a roughness value conversion means that calculates a converted roughness value equivalent to the roughness value of another measurement method by using the correlation between the laser light intensity distribution data, which is the distribution of the magnitude of the amount of reflected laser light at one measurement point, and the roughness value of another measurement method measured by a method other than laser light.

[0012] The surface roughness measuring device according to claim 6 is characterized in that, in addition to the configuration of claim 5, the roughness value conversion means derives a regression equation in advance from laser light intensity distribution data and roughness values ​​from other measurement methods, and calculates a converted roughness value using the regression equation.

[0013] The surface roughness measuring device according to claim 7 is characterized in that, in addition to the configuration of claim 6, the roughness value conversion means uses the maximum value, minimum value, mean value, and standard deviation of the laser light intensity distribution data in order to derive a regression equation.

[0014] The surface roughness measuring device according to claim 8 is characterized in that, in addition to the configuration of claim 6 or claim 7, the roughness value conversion means is prepared and used by providing a regression equation for each type of object to be measured and each type of converted roughness value to be converted.

[0015] The surface roughness measurement method according to claim 9 is characterized by irradiating the surface of an object to be measured with laser light at an angle of 5 to 45 degrees with the surface of the object to be measured, receiving the reflected laser light reflected at a measurement point on the surface of the object to be measured with a light receiving sensor, and calculating a laser light roughness value, which is the value of the surface roughness of the object to be measured, from the amount of light of the reflected laser light received by the light receiving sensor.

[0016] The surface roughness measurement method according to claim 10 is characterized in that, in addition to the configuration of claim 9, the laser roughness value is calculated from laser light intensity distribution data, which is the distribution of the magnitude of the reflected laser light intensity at one measurement point, when calculating the laser light roughness value.

[0017] The surface roughness measurement method according to claim 11 is characterized in that, in addition to the configuration of claim 10, the laser roughness value to be calculated is a variance value calculated from laser light intensity distribution data.

[0018] The surface roughness measurement method according to claim 12 is characterized in that, in addition to the configuration of any one of claims 9 to 11, the calculated laser roughness value is converted to a converted roughness value equivalent to that obtained when measured by a method other than laser light, based on its correlation with the roughness value obtained by a method other than laser light.

[0019] The surface roughness measurement method according to claim 13 is characterized by irradiating the surface of an object to be measured with laser light at an angle of 5 to 45 degrees with the surface of the object to be measured, receiving the reflected laser light reflected at a measurement point on the surface of the object to be measured with a light receiving sensor, and calculating a converted roughness value equivalent to the roughness value of other measurement methods using the correlation between the laser light intensity distribution data, which is the distribution of the magnitude of the reflected laser light at one measurement point, and the roughness value measured by other measurement methods other than laser light.

[0020] The surface roughness measurement method according to claim 14 is characterized in that, in addition to the configuration of claim 13, a regression equation is derived in advance from laser light intensity distribution data and roughness values ​​from other measurement methods when calculating the converted roughness value, and the converted roughness value is calculated using the regression equation.

[0021] The surface roughness measurement method according to claim 15 is characterized in that, in addition to the configuration of claim 14, it uses the maximum value, minimum value, mean value, and standard deviation of the laser light intensity distribution data in order to derive a regression equation.

[0022] The surface roughness measurement method according to claim 16 is characterized in that, in addition to the configuration of claim 14 or claim 15, a regression equation is prepared and used for each type of the object to be measured or the type of the converted roughness value to be converted.

Advantages of the Invention

[0023] According to the invention of the present application, the surface roughness can be measured even for an object to be measured moving at high speed.

Brief Description of the Drawings

[0024] [Figure 1] FIG. 1 is an explanatory diagram showing an example of the configuration of a surface roughness measurement apparatus according to the present invention. [Figure 2] FIG. 2 is an explanatory diagram showing the configuration of the optical system of the surface roughness measurement apparatus. [Figure 3] FIG. 3 is an explanatory diagram showing the distribution curve of the amount of reflected laser light of the surface roughness measurement apparatus. [Figure 4] FIG. 4 is an explanatory diagram showing an example of the amount of reflected laser light of the surface roughness measurement apparatus.

Embodiments for Carrying Out the Invention

[0025] Hereinafter, the embodiments of the present invention will be specifically described with reference to the drawings. FIG. 1 is an explanatory diagram showing an example of the configuration of a surface roughness measurement apparatus according to the present invention. FIG. 2 is an explanatory diagram showing the configuration of the optical system of the surface roughness measurement apparatus. FIG. 3 is an explanatory diagram showing the distribution curve of the amount of reflected laser light of the surface roughness measurement apparatus. FIG. 4 is an explanatory diagram showing an example of the amount of reflected laser light of the surface roughness measurement apparatus.

[0026] The surface roughness measuring device 1 shown in the figure is for measuring the surface roughness of an object W having a surface capable of reflecting laser light. The object W can be any material capable of reflecting laser light, as detailed later; examples include metal, resin, and rubber. The shape of the object W is not limited to a plate, but can also be a rod or a cylinder; however, shapes that cause the laser light reflected from the surface of the object W to not reach the light receiving sensor 20 (described later) are excluded, as measurement is not possible with such shapes.

[0027] The surface roughness measuring device 1 includes a laser light source 10 that irradiates laser light L toward the surface of the object W to be measured, and a light receiving sensor 20 that receives reflected laser light R (R1, R2) reflected from the laser light L of the laser light source 10 at the measurement point P on the surface of the object W to be measured. Although Figure 1 includes an optical system 22, which will be described in detail later, this optical system 22 is not essential.

[0028] The laser light source 10 receives power from the power supply 12 and emits laser light L, with a wavelength of 300 nm to 700 nm. More specifically, it is a red laser (center wavelength: red (650 nm)), a green laser (center wavelength: green (532 nm)), a violet laser (center wavelength: blue-violet (405 nm)), a blue laser (center wavelength: blue (375 nm)), etc. The laser light source 10 irradiates the measurement point P on the surface of the object to be measured W with the laser light L, with a predetermined elevation angle θ toward the object to be measured W. The elevation angle θ is between 5 and 45 degrees. The elevation angle θ should be appropriately determined depending on the material, thickness, and surface condition of the object to be measured W.

[0029] The light receiving sensor 20 receives the reflected laser light R(R1, R2) reflected at the measurement point P of the object W to be measured, and is, for example, a photodiode that outputs the amount of light received. The light receiving sensor 20 is positioned to receive the reflected laser light R(R1, R2) most accurately. In Figure 1, one light receiving sensor 20 is shown, but multiple light receiving sensors may be used to receive the reflected laser light R(R1, R2) at the measurement point P, or a single light receiving sensor with multiple light receiving elements may be used. As will be described later, since it is necessary to obtain the distribution of the magnitude of the reflected laser light R(R1, R2) reflected at a single measurement point P, multiple light receiving sensors will be used, or a single light receiving sensor with multiple light receiving elements will be used (the diagram shown in Figure 3(a) shows that light receiving elements 1 to 16 are arranged vertically on a single light receiving sensor 20, but this is not limited by the number of light receiving elements).

[0030] The light receiving sensor 20 is connected to the calculation means 50. The calculation means 50 includes a laser light roughness calculation means 30 and a roughness value conversion means 40 that calculate the laser light roughness value and converted roughness value, which are values ​​of the surface roughness of the object W to be measured, from the light intensity value of the light receiving sensor 20 (however, depending on the embodiment, there may be only either the laser light roughness calculation means 30 or the roughness value conversion means 40). The calculation means 50 may be an electronic computer such as a personal computer, or a digital processing means composed of logic circuits, and is not limited by its form.

[0031] Next, the operation of the surface roughness measuring device 1 will be explained. First, a laser beam L is shone onto the measurement point P of the object W to be measured, and the reflected laser beam R(R1, R2) is projected onto the light receiving sensor 20. When the surface roughness of the measurement point P is below a predetermined level, the amount of reflected laser beam R(R1, R2) received by the light receiving sensor 20 at a single measurement point P has a distribution curve C that shows a distribution of light amount like a normal distribution with a peak in the center and a curved slope that is evenly distributed on both sides, as shown in Figure 3(b). In Figure 3(b), the left-right direction shows the amount of light A, and the up-down direction shows the distribution B.

[0032] If the measurement point P has a predetermined surface roughness, the distribution curve will be trapezoidal, or the light intensity A of the distribution curve will be small overall, resulting in a light intensity value that differs from the distribution curve C, unlike in Figure 3(b). The present invention calculates the surface roughness value of an object W to be measured from the light intensity of reflected laser light R, and in particular, calculates the laser light roughness value and converted roughness value from laser light distribution data, which is the distribution of the magnitude of the light intensity of reflected laser light R at a single measurement point P on the surface of the object W to be measured.

[0033] Here, both the laser roughness value and the converted roughness value are numerical values ​​that indicate the surface roughness of the object W being measured. However, the laser roughness value is a numerical value of roughness calculated based on the magnitude of the laser light R, while the converted roughness value is a value equivalent to the numerical values ​​of roughness in the Japanese Industrial Standards JIS B 0601:2013, JIS B 0633:2001, and JIS B 0651:2001, which are calculated by converting the laser roughness value or directly from the distribution of the magnitude of the reflected laser light R. For example, it is a numerical value equivalent to the arithmetic mean roughness (hereinafter referred to as Ra), the maximum height roughness (hereinafter referred to as Rz), and the 10-point average roughness (hereinafter referred to as RzJIS).

[0034] Furthermore, in the context of the optical system, the surface roughness measuring device 1 will be described as a long, tubular object W whose surface can reflect the laser beam L. During measurement, the object W moves at a predetermined speed, and the surface roughness measuring device 1 measures the surface roughness of the moving object W.

[0035] As shown in Figure 1, the surface roughness measuring device 1 is equipped with an optical system 22 on the light-receiving side of the light-receiving sensor 20. As shown in Figure 2(b), the optical system 22 has two lenses 22a and 22b. This optical system 22 is a beam expander for expanding the diameter of the reflected laser light R. Although a beam expander is used as the optical system 22, it is also possible to use an optical system with other functions, taking into account the characteristics of the light-receiving sensor 20. The optical system 22 consists of a lens 22a that plays the role of expanding the beam diameter of the incident reflected laser light R, and a lens 22b that emits the expanded reflected laser light R1 as parallel light, which is reflected laser light R2. Ultimately, the light-receiving sensor 20 receives the reflected laser light R2. In the example in Figure 2, the optical system 22 expands the reflected laser light R to match the effective area of ​​the light-receiving element of the light-receiving sensor 20.

[0036] When measuring the surface roughness of an object W, as shown in Figure 2(a), the light receiving sensor 20 is positioned so as to extend vertically upward when viewed from the central axis direction of the object W. As shown in Figure 2(a), the light receiving sensor 20 is configured to receive light with a single light receiving sensor 20 having multiple light receiving elements, as shown in Figure 3(a), and it is shown that the light receiving elements are arranged vertically from 1 to 16 on a single light receiving sensor 20. Note that the number of light receiving elements on a single light receiving sensor is arbitrary, and it is also arbitrary whether or not all of the light receiving elements are used. The reflected laser light R(R1, R2) reflected from the measurement point P on the surface of the object W reaches the light receiving sensor 20.

[0037] Figure 4 shows, as an example, the waveform data of the reflected laser light R reflected at the measurement point P on the surface of the object W to be measured, which was received by the light receiving sensor 20. In each waveform in Figure 4, the horizontal axis represents the channel number (CN) of each individual light receiving element of the light receiving sensor 20, and the vertical axis represents the light intensity of each channel, with these values ​​connected in a line graph (note that the number of light receiving elements in the light receiving sensor in Figure 4 is not necessarily 16 (16 channels)). Figure 4(a) is the waveform when the surface of the object W to be measured is smooth, Figure 4(b) is the waveform when the surface of the object W to be measured is normal and average, and Figure 4(c) is the waveform when the surface of the object W to be measured is rough.

[0038] The following embodiments will describe examples of the operation of the laser roughness calculation means 30 and the roughness value conversion means 40.

[0039] With this configuration and operation, the surface roughness measuring device 1 can measure the surface roughness of the object W without contact, even if the object W is moving at high speed. [Examples]

[0040] This embodiment 1 describes the calculation of the laser roughness value by the laser roughness calculation means 30 and the calculation of the converted roughness value by the roughness value conversion means 40 using the laser roughness value calculated by the laser roughness calculation means 30.

[0041] First, the laser roughness calculation means 30 calculates a laser roughness value, which is the surface roughness value of the object W to be measured, from the amount of reflected laser light R received by the light receiving sensor 20. The method for calculating the laser roughness value of the laser roughness calculation means 30 is not limited, but one method is to calculate the laser roughness value from laser light intensity distribution data, which is the distribution of the magnitude of the amount of reflected laser light R at a single measurement point P (for example, the magnitude of the amount of reflected laser light R obtained from each light receiving element shown in Figure 3(a)).

[0042] A more specific method for calculating the laser roughness value using the laser roughness calculation means 30 is to calculate a variance value from laser light intensity distribution data (for example, the values ​​of the magnitude of the reflected laser light R obtained from each photodetector shown in Figure 3(a)), which is the distribution of the magnitude of the reflected laser light R at a single measurement point P, and use this variance value as the laser roughness value. Note that any method may be used to calculate the variance value.

[0043] Furthermore, the roughness value conversion means 40 in this embodiment 1 converts the laser roughness value calculated by the laser roughness calculation means 30 into a converted roughness value. Specifically, the laser roughness value calculated by the laser roughness calculation means 30 is converted to a converted roughness value equivalent to that obtained when measured by a method other than laser light, based on its correlation with the roughness value measured by a method other than laser light. Here, the roughness value measured by a method other than laser light is not limited to the values ​​according to the Japanese Industrial Standards (e.g., Ra, Rz, RzJIS) mentioned above, but using the values ​​according to the Japanese Industrial Standards (e.g., Ra, Rz, RzJIS) provides a highly versatile numerical value. A regression method can be considered for the conversion method, but the conversion method can be arbitrarily selected. Note that the roughness value conversion means 40 is not essential in the configuration of embodiment 1. [Examples]

[0044] In this embodiment 2, the operation of calculating the converted roughness value using the roughness value conversion means 40 will be described. The roughness value conversion means 40 in this embodiment 2 calculates a converted roughness value equivalent to the roughness value of other measurement methods (as described above) by using the correlation between the laser light intensity distribution data, which is the distribution of the magnitude of the amount of reflected laser light R at a single measurement point P, and the roughness value measured by other measurement methods other than laser light.

[0045] First, the roughness value conversion means 40 derives a regression equation in advance from the laser light intensity distribution data and the roughness values ​​from other measurement methods, and then calculates the converted roughness value from the laser light intensity distribution data of the measured object W using the pre-prepared regression equation.

[0046] For example, first, the laser light intensity distribution data of a reference object W is measured, and the roughness value of the same object W is measured using another measurement method according to the method specified in the Japanese Industrial Standards mentioned above. Then, a regression equation is calculated and stored from the laser light intensity distribution data of the reference object W and the roughness value of this reference object W. Then, by multiplying the laser light intensity distribution data of the object W to be measured by the previously stored regression equation, the converted roughness value of the object W to be measured can be obtained.

[0047] The method by which the roughness value conversion means 40 pre-determines the regression equation is arbitrary, but for example, the maximum value, minimum value, mean value, and standard deviation of the laser light intensity distribution data for a single measurement point P can be used. Examples of regression equations obtained by this method are shown in equations 1 to 9. In equations 1 to 9, Ra, RzJIS, and Rz represent the above-mentioned converted roughness values ​​(in μm), MAX represents the maximum value of the laser light intensity distribution data, MIN represents the minimum value of the laser light intensity distribution data, Average represents the mean value of the laser light intensity distribution data, and σ represents the standard deviation of the laser light intensity distribution data.

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[0057] Here, equations 1 to 3 are regression equations for bright steel bars whose surfaces are ground with a centerless grinder. Equations 4 to 6 are regression equations for bright steel bars that are cold-drawn through a die (mold). Equations 7 to 9 are regression equations for bright steel bars that are cut (turned) with a cutting tool.

[0058] Thus, the roughness value conversion means 40 can use a regression equation prepared for each type of object W to be measured or for each type of converted roughness value to be converted.

[0059] This invention allows for various embodiments and modifications without departing from the broad spirit and scope of the invention. Furthermore, the embodiments described above are for illustrative purposes only and do not limit the scope of the invention. In other words, the scope of the invention is indicated by the claims, not by the embodiments. Various modifications made within the scope of the claims and the equivalent scope of the meaning of the invention are considered to be within the scope of this invention. [Industrial applicability]

[0060] As described above, the present invention provides a surface roughness measuring device and a surface roughness measuring method that can measure the surface roughness of an object being measured even when it is moving at high speed. [Explanation of Symbols]

[0061] 1. Surface roughness measuring device 10. Laser light source 12...Power supply 20.....Light receiving sensor 22...Optical system 22a...Lens 22b...Lens 30. Laser roughness calculation method 40. Roughness value conversion method 50...Calculation method W...Object to be measured P...Measurement point L.....Laser light R·····Reflected laser light R1....Reflected laser light R2....Reflected laser light θ...Elevation angle A·····Light intensity B...Distribution C...Distribution curve

Claims

1. In a surface roughness measuring device that measures the surface roughness of an object to be measured having a surface capable of reflecting laser light, A laser light source that irradiates the surface of the object to be measured with the laser beam such that the angle between the laser beam and the surface of the object to be measured is between 5 and 45 degrees, A light receiving sensor that receives reflected laser light reflected at a measurement point which is the surface of the object to be measured, A surface roughness measuring device characterized by comprising: a laser light roughness calculation means that calculates a laser light roughness value, which is the value of the surface roughness of the object to be measured, from the amount of reflected laser light received by the light receiving sensor.

2. The laser roughness calculation means, The surface roughness measuring device according to claim 1, characterized in that it calculates the laser light roughness value from laser light intensity distribution data, which is the distribution of the magnitude of the amount of reflected laser light at one of the measurement points.

3. The laser roughness value calculated by the laser roughness calculation means is The surface roughness measuring device according to claim 2, characterized in that the variance value is calculated from the aforementioned laser light intensity distribution data.

4. The surface roughness measuring apparatus according to any one of claims 1 to 3, characterized in that it comprises a roughness value conversion means for converting the laser roughness value calculated by the laser roughness calculation means into a converted roughness value equivalent to that obtained when measured by a method other than laser light, based on the correlation with the roughness value measured by a method other than laser light.

5. In a surface roughness measuring device that measures the surface roughness of an object to be measured having a surface capable of reflecting laser light, A laser light source that irradiates the surface of the object to be measured with the laser beam such that the angle between the laser beam and the surface of the object to be measured is between 5 and 45 degrees, A light receiving sensor that receives reflected laser light reflected at a measurement point which is the surface of the object to be measured, A surface roughness measuring device characterized by comprising a roughness value conversion means that calculates a converted roughness value equivalent to the roughness value measured by another measurement method, using the correlation between laser light intensity distribution data, which is the distribution of the magnitude of the reflected laser light intensity at a single measurement point, and the roughness value measured by another measurement method other than laser light.

6. The roughness value conversion means is A regression equation is derived in advance from the laser light intensity distribution data and the roughness value from the other measurement method. The surface roughness measuring device according to claim 5, characterized in that the converted roughness value is calculated using the regression equation.

7. The roughness value conversion means is The surface roughness measuring device according to claim 6, characterized in that the maximum value, minimum value, mean value, and standard deviation of the laser light intensity distribution data are used to derive the regression equation.

8. The roughness value conversion means is The surface roughness measuring device according to claim 6 or 7, characterized in that the regression equation is prepared and used for each type of object to be measured or for each type of converted roughness value to be converted.

9. In a surface roughness measurement method for measuring the surface roughness of an object to be measured that has a surface capable of reflecting laser light, The laser beam is shone onto the surface of the object to be measured such that the angle between the laser beam and the surface of the object to be measured is between 5 and 45 degrees. The light receiving sensor receives the reflected laser light reflected from the surface of the object being measured at the measurement point, A surface roughness measurement method characterized by calculating a laser light roughness value, which is the value of the surface roughness of the object to be measured, from the amount of reflected laser light received by the light receiving sensor.

10. In calculating the aforementioned laser roughness value, The surface roughness measurement method according to claim 9, characterized in that the laser light roughness value is calculated from laser light intensity distribution data, which is the distribution of the magnitude of the amount of reflected laser light at one of the measurement points.

11. The laser roughness value to be calculated is The surface roughness measurement method according to claim 10, characterized in that the variance value is calculated from the aforementioned laser light intensity distribution data.

12. The surface roughness measurement method according to any one of claims 9 to 11, characterized in that the calculated laser roughness value is converted to a converted roughness value equivalent to that obtained when measured by a method other than laser light, based on its correlation with the roughness value obtained by a method other than laser light.

13. In a surface roughness measurement method for measuring the surface roughness of an object to be measured that has a surface capable of reflecting laser light, The laser beam is shone onto the surface of the object to be measured such that the angle between the laser beam and the surface of the object to be measured is between 5 and 45 degrees. The light receiving sensor receives the reflected laser light reflected from the surface of the object being measured at the measurement point, A surface roughness measurement method characterized by calculating a converted roughness value equivalent to the roughness value measured by other measurement methods, using the correlation between laser light intensity distribution data, which is the distribution of the magnitude of the reflected laser light intensity at a single measurement point, and the roughness value measured by other measurement methods other than laser light.

14. In calculating the aforementioned converted roughness value, A regression equation is derived in advance from the laser light intensity distribution data and the roughness value from the other measurement method. The surface roughness measurement method according to claim 13, characterized in that the converted roughness value is calculated using the regression equation.

15. The surface roughness measurement method according to claim 14, characterized in that the maximum value, minimum value, mean value, and standard deviation of the laser light intensity distribution data are used to derive the regression equation.

16. The surface roughness measurement method according to claim 14 or 15, characterized in that the regression equation is prepared and used for each type of object to be measured or for each type of converted roughness value to be converted.

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