JP2011117795A - Method and device for measuring surface properties - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To quantitatively and readily measure the surface roughness of a recessed section or a hollow section of a non-flat article, in particular, the surface roughness of an inner peripheral surface of the recessed section or an inner peripheral surface of the hollow section, in a noncontact manner and with high accuracy. <P>SOLUTION: A pattern is irradiated by a pattern forming device 11, reflected by a half mirror 13, further reflected by a mirror, and vertically projected to the inner peripheral surface of the recessed section or the inner peripheral surface of the hollow section of the non-flat article as an object 2 to be measured, and the reflected pattern is reflected by the mirror 14, and transmitted across the half mirror 13, and its image is picked up by an image pick-up section 3 (digital camera, and the like). Data of the obtained image signal is processed by a computer 3 to thereby measure and evaluate the surface property of a surface 22 to be measured. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a surface texture measuring method and a surface texture measuring apparatus for measuring the surface roughness of a concave inner surface or a hollow inner surface of a non-flat object.

  As a device that measures and evaluates the surface properties of a smooth surface close to a mirror surface, a device that takes a reflected image of a pattern with a camera, processes the video signal with a computer, and measures the surface properties quantitatively without contact. (For example, refer to Patent Documents 1 and 2).

JP 2001-99632 A JP 2006-84452 A

  However, in the above-described conventional apparatus for measuring the surface properties by taking a reflected image or virtual image of a pattern with a camera and processing the video signal with a computer, the pattern is inclined at a predetermined angle with respect to the normal to the surface to be measured. Projecting and reflecting to the opposite side at the same angle, which is suitable for measuring the flat surface of a flat object such as a polished steel plate, but is not a flat plate such as a mold or cylinder It is not suitable for measuring the inside of a concave portion or hollow portion of an object. Even if an attempt is made to measure the inside of such a concave portion or hollow portion of a non-flat object, if the periphery of the measurement target surface is narrow, an optical path or the like for pattern projection and reflection cannot be secured.

  The present invention is a surface that can measure the surface roughness of a recess or hollow part of a non-flat object, particularly the surface roughness of the inner peripheral surface of the recess or the inner peripheral surface of the hollow part, in a non-contact manner, quantitatively, accurately, and simply. An object is to provide a property measuring method and a surface property measuring apparatus.

  The surface texture measuring method of the present invention is a method for measuring the surface roughness of a concave inner surface or a hollow inner surface of a non-flat object such as a mold or a cylinder, and is a pattern showing a two-dimensional optical bright / dark distribution shape. Is irradiated in a direction substantially perpendicular to the vertical axis of the concave portion or hollow portion of the non-flat object, reflected by the half mirror toward the bottom surface of the concave portion or the bottom surface of the hollow portion, and further reflected by the mirror to be the concave portion that is the measurement target surface The pattern projected on the inner peripheral surface or the inner peripheral surface of the hollow portion substantially perpendicularly and reflected by the inner peripheral surface of the concave portion or the inner peripheral surface of the hollow portion is reflected by the mirror, and is further transmitted through the half mirror and photographed by the image sensor. The surface roughness of the inner peripheral surface of the concave portion or the inner peripheral surface of the hollow portion is evaluated by data processing of the video signal obtained by the above in a computer.

  In this method, the non-flat object that is the measurement object is arranged so that the measurement target surface of the inner peripheral surface of the concave portion or the inner peripheral surface of the hollow portion is substantially parallel to the pattern. Then, the pattern is reflected by the half mirror, further reflected by the mirror, and projected onto the surface to be measured substantially perpendicularly. At this time, the reflected image of the pattern projected on the measurement target surface and reflected by the mirror appears substantially perpendicular to the surface on which the pattern is arranged. This reflected image is photographed by the imaging element from the open side of the concave portion or hollow portion of the non-flat object through the half mirror. Then, the video signal is processed by a computer to evaluate the surface roughness of the measurement target surface. In this case, it is easy to secure an optical path for pattern projection and reflection. For example, the surface roughness of the inner peripheral surface of a concave portion or the inner peripheral surface of a hollow portion of a non-flat object such as a mold or a cylinder is determined without contact. Therefore, it is possible to measure accurately and easily. The computer processing in this case is, for example, obtaining a luminance distribution from the video signal, calculating a standard deviation of the luminance distribution, and evaluating the surface roughness of the measurement target surface based on the standard deviation of the luminance distribution. It's okay.

  In this surface texture measurement method, a non-flat object, which is a measurement object, is arranged so that the measurement object surface is substantially parallel to the pattern, the pattern is reflected by a half mirror, and further reflected by a mirror. The image projected onto the surface perpendicularly, reflected on the measurement target surface, and further reflected on the mirror can be taken by the image sensor from a direction parallel to the measurement target surface.

  By doing this, the optical axis of the projection optical system that reflects the pattern with the half mirror, and further reflects with the mirror and projects it onto the surface to be measured, and the pattern reflected by the surface to be measured are reflected with the mirror, and further the half mirror The optical axis of the imaging optical system that transmits the light and forms an image on the imaging element is coaxial between the half mirror and the measurement target surface. At this time, the reflected image of the pattern projected on the measurement target surface and reflected by the mirror appears substantially perpendicular to the surface on which the pattern is arranged. This reflected image is photographed by the imaging element from the open side of the concave portion or hollow portion of the non-flat object through the half mirror. Then, the video signal is processed by a computer to evaluate the surface roughness of the measurement target surface. In this case, it is easy to secure an optical path for pattern projection and reflection. For example, the surface roughness of the inner peripheral surface of a concave portion or the inner peripheral surface of a hollow portion of a non-flat object such as a mold or a cylinder is determined without contact. Therefore, it is possible to measure accurately and easily. In particular, since the optical axis of the projection optical system and the optical axis of the imaging optical system are coaxial between the half mirror and the measurement target surface, it becomes easier to secure the optical path, even in a deep part of a recess or a hollow part. Easy to measure.

  In this surface property measurement method, it is preferable that the image sensor is focused on the pattern image reflected through the measurement target surface, and the pattern projected on the measurement target surface is imaged on the virtual image plane and photographed.

  In addition, in this surface texture measurement method, by changing the angle of the mirror with respect to the image sensor, the measurement area on the inner peripheral surface of the concave portion or the inner peripheral surface of the hollow portion can be moved. Even if the surface is inclined with respect to the surface including the longitudinal axis of the concave portion or the hollow portion, the surface roughness can be easily measured.

  Further, in this surface property measurement method, the mirror can be rotated about the longitudinal axis of the concave portion or the hollow portion to move the measurement area on the inner peripheral surface of the concave portion or the inner peripheral surface of the hollow portion. Thus, the surface roughness of the inner peripheral surface of the concave portion or the inner peripheral surface of the hollow portion can be measured over the entire periphery.

  Further, the surface texture measuring device of the present invention measures the surface roughness of a concave portion or a hollow portion of a non-flat object such as a mold or a cylinder, and has a striped shape showing a two-dimensional distribution shape of optical brightness. Is irradiated in a direction substantially perpendicular to the longitudinal axis of the concave portion or hollow portion of the non-flat object, reflected by the half mirror toward the bottom surface of the concave portion or the hollow portion, and further reflected by the mirror to be measured. The projection optical system that projects perpendicularly to the inner peripheral surface of the concave part or hollow part of the non-flat object that is a surface, and the pattern that is projected by the projection part and reflected by the inner peripheral surface of the concave part or hollow part is reflected by the mirror In addition, the image pickup optical system that passes through the half mirror and shoots with the image pickup device is used. The image signal obtained by the image pickup device is processed by a computer to process the data on the inner peripheral surface of the recess or hollow. And evaluating the surface roughness of the inner circumferential surface.

  In this apparatus, a non-flat object, which is a measurement object, is arranged with a projection optical system in a state where the measurement target surface of the inner peripheral surface of the recess or the inner peripheral surface of the hollow part is substantially parallel to the pattern. The light is reflected by a half mirror, further reflected by a mirror, and projected substantially perpendicularly onto the surface to be measured. Then, the reflection image projected on the measurement target surface and reflected by the mirror is transmitted through the half mirror, and is photographed by the imaging element of the imaging optical system from the open side of the concave portion or the hollow portion of the non-flat object, and the video signal is captured by the computer. The surface roughness of the measurement target surface is evaluated by data processing. In this case, it is easy to secure an optical path for pattern projection and reflection. For example, the surface roughness of the inner peripheral surface of a concave portion or the inner peripheral surface of a hollow portion of a non-flat object such as a mold or a cylinder is determined without contact. Therefore, it is possible to measure accurately and easily. The computer processing in this case is, for example, obtaining a luminance distribution from the video signal, calculating a standard deviation of the luminance distribution, and evaluating the surface roughness of the measurement target surface based on the standard deviation of the luminance distribution. It's okay.

  And this surface property measuring apparatus can make the optical axis of a projection optical system, and the optical axis of an imaging optical system coaxial with a half mirror and a measurement object surface.

  In this case, the non-flat object that is the measurement object is arranged so that the inner peripheral surface of the recess or the inner peripheral surface of the hollow part that is the measurement target surface is substantially parallel to the pattern. Then, the pattern is reflected by the half mirror, further reflected by the mirror, projected perpendicularly to the measurement target surface, reflected by the measurement target surface, and further the image reflected by the mirror is taken from the direction parallel to the measurement target surface. Shoot by. At this time, the reflected image of the pattern projected on the measurement target surface and reflected by the mirror appears substantially perpendicular to the surface on which the pattern is arranged. The reflected image is transmitted through a half mirror, photographed by an image sensor from the open side of a concave or hollow portion of a non-planar object, and the surface roughness of the measurement target surface is evaluated by processing the video signal with a computer. . In this case, it is easy to secure an optical path for pattern projection and reflection. For example, the surface roughness of the inner peripheral surface of a concave portion or the inner peripheral surface of a hollow portion of a non-flat object such as a mold or a cylinder is determined without contact. Therefore, it is possible to measure accurately and easily. In particular, since the optical axis of the projection optical system and the optical axis of the imaging optical system are coaxial between the half mirror and the measurement target surface, it becomes easier to secure the optical path, even in a deep part of a recess or a hollow part. Easy to measure.

  Moreover, in this surface texture measuring apparatus, the mirror can change the angle with respect to the image sensor. By doing so, it becomes possible to move the measurement region on the inner peripheral surface of the concave portion or the inner peripheral surface of the hollow portion by changing the angle of the mirror with respect to the imaging element, and the measurement target surface includes the vertical axis of the concave portion or the hollow portion. Even if it is inclined with respect to the surface, the surface roughness can be easily measured.

  In this surface texture measuring apparatus, the mirror can be rotated about the longitudinal axis of the concave portion or the hollow portion. By doing so, it becomes possible to move the measurement area on the inner peripheral surface of the concave portion or the inner peripheral surface of the hollow portion by rotating the mirror around the longitudinal axis of the concave portion or the hollow portion. The surface roughness of the inner peripheral surface can be measured over the entire circumference.

  In this surface texture measuring apparatus, the irradiation unit may be provided with a display that forms a pattern controllable by a computer, for example.

  In that case, for example, by using the contrast of the pattern formed on a display such as a liquid crystal as an element of the imaging system, the shape and directionality of the pattern can be determined by the computer according to the surface roughness, finishing direction, etc. By adjusting the pitch and the like, an optimum pattern can be obtained.

  The display for forming the pattern may be a display other than a liquid crystal display, such as plasma, organic / inorganic EL, or the like. The projection unit may project the slit pattern by applying light from the light source to the slit plate from behind, or may project the reflected image by illuminating the print pattern.

  As is clear from the above description, according to the present invention, the surface roughness of the inner peripheral surface of the concave portion or the inner peripheral surface of the non-flat object is measured in a non-contact, quantitative, accurate and simple manner. be able to. In particular, it is possible to measure the surface roughness of 1n (nano) to 100n near the mirror surface.

It is the schematic of the surface property measuring system which concerns on an example of embodiment of this invention.

  FIG. 1 shows an example of an embodiment of the present invention. In this embodiment, for example, the surface properties of the inner peripheral surface of a concave portion or the inner peripheral surface of a hollow portion of a non-flat object such as a mold or a cylinder are measured and evaluated. In the figure, 1 is a surface texture measuring device, 2 is an object to be measured, and 3 is a computer.

  The surface texture measuring device 1 includes a pattern forming device 11 that forms and irradiates a two-dimensional distribution pattern of optical brightness such as a striped pattern, an imaging device 12 that captures a reflected image of the pattern, a half mirror 13, The pattern forming device 11 is used to form a pattern showing a two-dimensional optical bright and dark distribution shape in a direction substantially orthogonal to the vertical axis of the concave portion or hollow portion of the non-flat object that is the measurement object 2. Irradiated, reflected by the half mirror 13 toward the bottom surface 21 of the recess or hollow part, and further reflected by the mirror 14 to measure the measurement object surface 22 (non-flat object) of the measurement object 2 (non-flat object) The pattern projected on the surface substantially perpendicular to the circumferential surface (projected at an angle of 90 degrees in the figure) and reflected by the measurement symmetry surface 22 (inner circumferential surface of the recess or inner circumferential surface of the hollow portion) is reflected by the mirror 14. Was Isa is configured to shoot by the image pickup device by transmitting the half mirror 13.

  The imaging device 12 includes an area image sensor such as a CCD, CMOS, or digital camera as an image sensor.

  As shown in FIG. 1, the measurement object 2 (non-flat object) is such that the measurement object surface 21 (the inner surface of the recess or the inner surface of the hollow portion) is parallel to the pattern formed by the pattern forming device 11. (In the example of the figure, the pattern is arranged in the vertical direction, and the measurement target surface is arranged in the vertical direction.) Then, a pattern showing a two-dimensional distribution pattern of optical brightness is irradiated in a direction substantially perpendicular to the longitudinal axis of the concave portion or hollow portion of the measurement object 2 (non-flat object), reflected by the half mirror 13, and further reflected by the mirror 14. And is projected substantially perpendicularly onto the measurement target surface 22 (the inner surface of the recess or the inner surface of the hollow portion).

  In the example of the figure, the pattern is irradiated in a direction (horizontal direction) orthogonal to the vertical axis of the concave portion or hollow portion of the non-flat object that is the measurement object 2. The half mirror 13 is arranged at an angle of 45 degrees with respect to the horizontal direction, the mirror 14 is also arranged at an angle of 45 degrees with respect to the horizontal direction, and the pattern image reflected by the half mirror 13 and further reflected by the mirror 14 is obtained. It is projected onto the measurement target surface 22 at an angle of 90 degrees.

  At this time, the reflected image of the pattern projected onto the measurement target surface 22 appears perpendicular to the surface on which the pattern is arranged via the mirror 14. The reflected image is transmitted through the half mirror 13 and is imaged by the imaging device of the imaging device 12 from the open side of the concave portion or the hollow portion of the measuring object 2 (non-flat object).

  In this case, the pattern is reflected by the half mirror 13, and further reflected by the mirror 14 and projected onto the measurement target surface 22, and the pattern reflected by the measurement target surface 22 is imaged on the image sensor. The optical axis of the imaging optical system is coaxial between the half mirror 13 and the measurement target surface 22.

  At the time of photographing, in the illustrated method, the focus of the photographing device 12 (imaging device) is adjusted to the virtual image surface 4 in which the pattern reflected by the measurement target surface 22 forms an image, and the pattern image formed on the virtual image surface 4 is mirrored. The image is reflected by 14, transmitted through the half mirror 13, and imaged by the imaging element of the imaging device 12 from the open side of the concave portion or the hollow portion of the measurement object 2 (non-flat object).

  In focusing, the focal length of the image sensor is fixed, and either the position of the surface texture measuring device 1 itself or the position of the table on which the measuring object 2 is placed is adjusted to adjust the mirror 14 and the measuring object surface. This is preferably done by adjusting the distance to 22. By doing so, focusing can be performed easily.

  Then, the video signal obtained by the imaging device is subjected to data processing by the computer 3 to measure and evaluate the surface property of the measurement target surface 22.

  It is preferable that the mirror 14 can change the angle with respect to the imaging device 12 (imaging device). By changing the angle of the mirror 14 with respect to the imaging device 12 (imaging device), it is possible to move the measurement region on the inner peripheral surface of the concave portion or the inner peripheral surface of the hollow portion. Or even if it inclines with respect to the surface containing the vertical axis | shaft of a hollow part, surface roughness can be measured easily.

  The processing by the computer in this case may be, for example, obtaining a luminance distribution from the video signal, calculating a standard deviation of the luminance distribution, and evaluating the surface roughness based on the standard deviation of the luminance distribution. There is a relatively linear correlation between the standard deviation of the luminance value distribution and the standard deviation of the surface inclination angle distribution due to surface irregularities, and the surface roughness can be evaluated by the standard deviation of the luminance distribution. In addition, there are various methods for measuring and evaluating surface properties by combining characteristics such as the degree of blurring, distortion, contrast, and brightness of the image of the imaging system composed of the measurement target surface, lens system, and image sensor. Is available.

  As the pattern forming apparatus 11, a liquid crystal display that forms a pattern controllable by a computer can be used. In that case, by using the contrast of the pattern formed on the liquid crystal display as an element of the imaging system, the shape, directionality, and pitch of the pattern are determined by the computer according to the surface roughness, finishing direction, etc. of the measurement target surface 22. Etc. can be adjusted, and an optimum pattern can be formed.

  In addition to the liquid crystal display, plasma, organic / inorganic EL or other displays may be used for the pattern forming apparatus 11. In addition, the slit pattern may be projected by applying light from the light source to the slit plate from behind, or the reflected image may be projected by illuminating the printed pattern.

  According to this embodiment, an optical path for pattern projection and reflection can be ensured as long as the mirror 14 is inserted, even inside the recess or hollow portion. For example, in the recess of a non-flat object such as a mold or a cylinder. The surface roughness of the peripheral surface and the inner peripheral surface of the hollow part can be measured in a non-contact, quantitative, accurate and simple manner. In particular, when the optical axis of the projection optical system and the optical axis of the imaging optical system are coaxial between the half mirror and the measurement target surface, it is easy to secure an optical path, and measurement is easy even in a deep part of a recess or hollow part. it can. However, it is not always necessary that the optical axis of the projection optical system and the optical axis of the imaging optical system are strictly coaxial between the half mirror 13 and the mirror 14.

  It is preferable that the mirror 14 can change the angle with respect to the imaging device 12 (imaging device). By doing so, it becomes possible to move the measurement region on the inner peripheral surface of the concave portion or the inner peripheral surface of the hollow portion, and even if the measurement target surface 22 is inclined with respect to the surface including the vertical axis of the concave portion or the hollow portion. The surface roughness can be easily measured.

  The mirror 14 is preferably rotatable about the longitudinal axis of the concave portion or hollow portion. By doing so, the measurement area | region in a recessed part inner peripheral surface or a hollow part inner peripheral surface can be moved, and the surface roughness of a recessed part inner peripheral surface or a hollow part inner peripheral surface can be measured over a perimeter.

DESCRIPTION OF SYMBOLS 1 Surface texture measuring apparatus 11 Pattern formation apparatus 12 Imaging device 13 Half mirror 14 Mirror 2 Measurement object 21 Bottom surface 22 Measurement object surface 3 Computer 4 Virtual image surface

Claims (10)

A surface property measurement method for measuring the surface roughness of the inner peripheral surface of the recess or the inner peripheral surface of the hollow part of the non-flat object,
A pattern showing a two-dimensional distribution shape of optical brightness is irradiated in a direction substantially perpendicular to the longitudinal axis of the concave portion or hollow portion of the non-flat object, and reflected by the half mirror toward the bottom surface of the concave portion or the hollow portion. Further, it is reflected by a mirror and projected substantially perpendicularly to the inner peripheral surface of the concave portion or the inner peripheral surface of the hollow portion, which is the measurement target surface,
The pattern reflected on the inner peripheral surface of the concave portion or the inner peripheral surface of the hollow portion is reflected by the mirror, and further, the half mirror is transmitted and photographed by the imaging device,
A surface property measuring method characterized by evaluating the surface roughness of the inner peripheral surface of the concave portion or the inner peripheral surface of the hollow portion by performing data processing on a video signal obtained by the image pickup device with a computer. A non-flat object that is a measurement object is arranged so that the measurement target surface is substantially parallel to the pattern, and the pattern is reflected by the half mirror, and further reflected by the mirror and projected perpendicularly to the measurement target surface. 2. The surface property measuring method according to claim 1, wherein an image reflected by the measurement target surface and further reflected by the mirror is photographed by the image sensor from a direction parallel to the measurement target surface. 3. The surface property according to claim 1, wherein the image sensor is focused on a pattern image reflected through the measurement target surface, and a pattern projected on the measurement target surface is imaged on a virtual image surface and photographed. Measuring method. The surface property measurement method according to claim 2 or 3, wherein a measurement region on the inner peripheral surface of the concave portion or the inner peripheral surface of the hollow portion is moved by changing an angle of the mirror with respect to the imaging element. 5. The surface according to claim 2, 3 or 4, wherein the measurement region on the inner peripheral surface of the concave portion or the inner peripheral surface of the hollow portion is moved by rotating the mirror about the longitudinal axis of the concave portion or the hollow portion. Property measurement method. A surface texture measuring device for measuring the surface roughness of the inner peripheral surface of a concave portion or the inner peripheral surface of a hollow portion of a non-flat object,
A pattern showing a two-dimensional distribution shape of optical brightness is irradiated in a direction substantially perpendicular to the longitudinal axis of the concave portion or hollow portion of the non-flat object, and reflected by the half mirror toward the bottom surface of the concave portion or the hollow portion. Further, a projection optical system for projecting perpendicularly to the inner peripheral surface of the concave portion or the inner peripheral surface of the hollow portion of the non-flat object that is the measurement target surface by being reflected by a mirror,
A pattern projected by the projection unit and reflected from the inner peripheral surface of the recess or the inner peripheral surface of the hollow portion is reflected by the mirror, and further includes an imaging optical system that transmits through the half mirror and captures an image by the imaging device.
A surface texture measuring apparatus characterized by evaluating the surface roughness of the inner peripheral surface of the concave portion or the inner peripheral surface of the hollow portion by performing data processing on a video signal obtained by the imaging device with a computer. 7. The surface property measuring apparatus according to claim 6, wherein the optical axis of the projection optical system and the optical axis of the imaging optical system are coaxial between the half mirror and the measurement target surface. The surface texture measuring device according to claim 7, wherein the mirror is capable of changing an angle with respect to the image sensor. The surface texture measuring apparatus according to claim 7, wherein the mirror is rotatable about a longitudinal axis of the concave portion or the hollow portion. The surface property measuring apparatus according to claim 6, wherein the irradiation unit includes a display that forms a pattern controllable by a computer.

Images