JP2009250708A - Measurement device and measurement method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that in a measurement method of a hollow shape by an existing technology, a hollow shape of an object is not obtained simultaneously and the object or a light source has to be rotated so that a device may be complicated, and to solve the problem of preciseness. <P>SOLUTION: This measurement device is adapted to measure an inner shape of a hollow cylindrical object to be measured. The measurement device includes a light transmission section for transmitting light in a first direction as an axial direction of the hollow cylindrical object, a change section for changing an advancing direction of the light to a direction perpendicular to the first direction, a modulation section for applying a physical modulation to the light so as to identify the light changed by the change section in the first direction, a detection section for detecting information about focusing of the light reflected at the inside of the object to be measured in the light of which the direction is changed by the change section and information about the physical modulation, and a shape measurement section for measuring the inner shape of the object to be measured by obtaining a deviation from a predetermined reference position on the basis of the detected result of the detection section. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a measuring apparatus and a measuring method for measuring a hollow shape of an object.

Conventionally, a distance sensor method, an oblique incidence optical system method, and the like are known as methods for measuring the hollow shape of an object without contact. For example, the distance sensor method is a method of measuring the hollow shape of an object by projecting laser light inside the hollow and measuring the displacement of reflected light while rotating the object (see, for example, Patent Document 1).
JP 2006-38820 A

  The distance sensor method according to the prior art cannot obtain a hollow shape of an object at a time, and it is necessary to rotate the object and the light source, which not only complicates the apparatus but also has a problem in accuracy.

  An object of the present invention is to provide a hollow shape measuring apparatus and a measuring method with little error.

  A measuring apparatus according to the present invention is a measuring apparatus that measures an inner shape of a hollow cylindrical object to be measured, and a light transmitting unit that transmits light in a first direction that is an axial direction of the hollow cylindrical object; , Converting the light in a direction substantially orthogonal to the first direction, a conversion unit that converts the traveling direction of the light, and performing physical modulation so that the light converted by the conversion unit can be distinguished in the first direction. A modulation unit that provides, a detection unit that detects focusing information of light reflected from the inside of the object to be measured among light whose direction has been converted by the conversion unit, and information on the physical modulation; and And a shape measuring unit that measures an inner shape of the object to be measured by obtaining a deviation from a predetermined reference position based on a detection result.

  Further, the detection unit is capable of detecting a first edge position that is one end portion and a second edge position that is the other end portion in the first direction of the light subjected to the physical modulation. Features.

  Further, the apparatus further includes a moving unit that relatively moves the conversion unit and the device under test in the first direction, and the shape measuring unit is configured to measure the device under measurement at a plurality of relative positions with the conversion unit and the device under test. It is characterized by measuring the inner shape of an object.

  The light transmitting unit includes a light source that generates the light, a first optical system that guides light from the light source and has a focal point at a reference position, and is closer to the light source than the focal point. A first light limiting member disposed at a position conjugate with the focal point of the system and having an opening of a predetermined shape; and a second optical system that forms an image of light returned from the object to be measured, and the detection unit Is arranged on a non-imaging plane translated in the optical axis direction from an imaging plane on which an image of the object at the reference position is formed by the second optical system, and receives light from the light source. A light receiving unit having a conjugate relation with the reference position is provided.

  In addition, a second light limiting member having an opening having a predetermined shape for shielding a part of a light beam irradiated from the first light limiting member to the object to be measured is provided.

  Further, the present invention is characterized in that a color filter is provided that applies different modulations on the first edge side and the second edge side at both ends of the light beam transmitted through the second light limiting member.

  In addition, there is provided a shape variable mechanism that arbitrarily changes at least one edge shape of the first edge side and the second edge side of both ends of the light beam transmitted through the second light limiting member into a concentric shape. To do.

  Further, the detection unit detects the first edge position and the second edge position by performing color detection of a light beam that is projected when the light beam that has passed through the color filter is reflected inside the object to be measured. It is characterized by that.

  Further, the light transmitter is disposed at a position where light is transmitted from a direction different from the first direction, and the light transmitter transmits light between the object to be measured and the light transmitter. A half mirror is provided that reflects light in the first direction and transmits light returning from the object to be measured to the light receiving unit side.

  Further, the conversion unit is constituted by a conical mirror.

  The first light limiting member may be a circular slit.

  A measuring method according to the present invention is a measuring method for measuring an inner shape of a hollow cylindrical object to be measured, and a light transmitting unit transmits light transmitted in a first direction which is the axial direction of the hollow cylindrical shape. The traveling direction of the light is converted to a direction substantially orthogonal to the first direction, and the light whose traveling direction has been converted is subjected to physical modulation in the first direction so as to be distinguishable in the first direction by the modulator. The deviation from the predetermined reference position is determined based on the detection result obtained by detecting the focusing information of the light reflected inside the object to be measured and the information of the physical modulation among the light subjected to the local modulation. The inner shape of the object to be measured is measured by obtaining the measurement object.

  Further, the first edge position which is one end portion and the second edge position which is the other end portion in the first direction of the light subjected to the physical modulation are detected.

  Further, the detection is performed while relatively moving the conversion unit and the device under test in the first direction, and the inner shape of the device under test is measured at a plurality of relative positions with the conversion unit and the device under test. It is characterized by doing.

  ADVANTAGE OF THE INVENTION According to this invention, the inner side shape of the hollow cylindrical to-be-measured object which has an inclination in an inner surface can be measured.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(First embodiment)
FIG. 1 is a block diagram of a hollow shape measuring apparatus 101 according to the first embodiment. The hollow shape measuring apparatus 101 obtains a cross-sectional shape by measuring the inner shape of a hollow cylindrical object at a predetermined height, and synthesizes the obtained cross-sectional shape in the height direction to form a three-dimensional hollow shape of the object. It is a device that constructs automatically.

  The hollow shape measuring apparatus 101 includes a light source system 102, a circular slit 103, a light limiting slit 104, an illumination lens 105, a half mirror 106, an objective lens 107, a conical mirror 108, an imaging lens 110, The imaging unit 111, the image processing unit 112, the Z-axis drive unit main body 113, the moving unit 114, and the personal computer 115 are configured.

  Note that an optical system (first optical system) including a light source system 102, an illumination lens 105, and an objective lens 107, and a circular slit 103 (first optical system) disposed at a position conjugate with the focal point of the first optical system. And the imaging lens 110 (second optical system) that forms an image of the light returned from the DUT 109 on the light receiving surface of the imaging unit 111 constitutes a light transmission unit. The half mirror 106 belongs to both the first optical system and the second optical system. The half mirror 106 transmits light from the light source system 102 to the measured object 109 side and transmits light returned from the measured object 109 to the imaging unit. It plays the role of sending to the 111 side. Further, the light source system 102, the circular slit 103, the light limiting slit 104, the illumination lens 105, the half mirror 106, the objective lens 107, the conical mirror 108, the imaging lens 110, and the imaging unit 111 are supported and integrated by the moving unit 114. Thus, the measurement optical system is configured and moved up and down. The light limiting slit 104 (second light limiting member) is disposed closer to the object to be measured 109 than the circular slit 103.

  The moving unit 114 includes a portion where the light of the light source system 102 is incident on the half mirror 106, and a tip portion 114a of the moving unit 114 which is inserted into the object to be measured 109 in the circumferential direction of the conical mirror 108. Made of transparent material. The moving unit 114 is driven up and down in the direction of the central axis C1 by a Z-axis driving unit main body 113 fixed to a base (not shown). The distal end portion 114 a of the moving unit 114 enters and exits the concave portion of the measurement object 109 and measures the inner shape of the measurement object 109.

  The light emitted from the light source system 102 enters the light limiting slit 104 through the slit 103a of the circular slit 103 corresponding to the field stop. When the light beam passes through the light restricting slit 104, half of the light beam (for example, the light beam 151 at the inner portion centering on the one-dot chain line 154 indicating the center of the light beam) is blocked and is not output to the illumination lens 105 side.

  Here, the shapes of the circular slit 103 and the light limiting slit 104 will be described in detail with reference to FIG. The circular slit 103 shown in FIG. 2A is provided with a slit 103a that transmits light irradiated from the light source system 102 in a ring shape. Here, an alternate long and short dash line 154 in FIGS. 1 and 2A indicates the center position of the ring-shaped light beam.

  On the other hand, the light limiting slit 104 shown in FIG. 2B is provided with a ring-shaped slit 104a that shields the inner side of the light beam transmitted through the slit 103a of the circular slit 103 and transmits only the outer light beam. For this reason, the light flux inside the alternate long and short dash lines C2 and C3 is shielded, and only the light flux outside the alternate long and short dashed lines C2 and C3 is transmitted. In the case of FIG. 2B, since the inner diameter of the ring-shaped slit 104a is at the position of the alternate long and short dash line 154 indicating the center position of the ring-shaped light beam, the ring-shaped slit 104a transmits only the outer half of the light beam.

  The ring-shaped slit 104a is fitted with filters 104b and 104c of different colors concentrically. The filter 104b and the filter 104c are disposed at positions that separate the inner portion and the outer portion of the light beam that passes through the ring-shaped slit 104a, as indicated by alternate long and short dash lines C7 and C8. For this reason, the inside of the light beam that has passed through the light limiting slit 104 becomes light of the color of the filter 104b, and the outside of the light beam that has passed through the light limiting slit 104 becomes light of the color of the filter 104c. Note that the boundary between the filter 104b and the filter 104c is not necessarily at the center position of the slit 104a.

  Here, the circular slit 103 and the light limiting slit 104 can be realized, for example, by controlling the liquid crystal so as to transmit light in a ring shape using a liquid crystal plate. Alternatively, a method such as vapor-depositing a light shielding part on a glass plate or the like or etching a transmissive part may be used. Further, the sensitivity of the imaging unit 111 changes depending on the shielding rate. The filter 104b and the filter 104c may be realized by vapor-depositing a color on the slit 104a portion of the light limiting slit 104.

  The light whose half of the light beam is blocked by the light limiting slit 104 enters the half mirror 106 through the illumination lens 105. The half mirror 106 converts the direction of incident light and reflects it to the objective lens 107 side. Here, if the direction of light reflected by the half mirror 106 is defined as the first direction, the light reflected in the first direction by the half mirror 106 is transmitted to the conical mirror 108 via the objective lens 107. The conical mirror 108 irradiates horizontally toward the inside of the object 109 to be measured in the entire circumferential direction substantially orthogonal to the first direction. That is, the conical mirror 108 acts as a conversion unit that changes the direction of light in a direction substantially orthogonal to the first direction.

  The light irradiated horizontally from the conical mirror 108 is reflected inside the object to be measured 109, is incident again on the conical mirror 108, is reflected on the objective lens 107 side, and then the half mirror 106 and the imaging lens. An image is formed on the light receiving surface of the imaging unit 111 through 110. Note that the light receiving surface of the imaging unit 111, the circular slit 103 that forms the field stop, and the reference position where the DUT 109 is placed are optically conjugate positions, and these three places are in focus. It has become. Further, the ring center of the ring-shaped light beam reflected by the half mirror 106 is coincident with the center of the conical mirror 108.

  Here, the shape of the conical mirror 108 will be described with reference to FIG. 3A is a perspective view of the conical mirror 108, FIG. 3B is a top view, and FIG. 3C is a side view. An alternate long and short dash line 154 indicating the center of the light beam reflected in the first direction through the half mirror 106 is reflected in a direction substantially orthogonal to the first direction by the mirror portion 108a inclined outward from the conical mirror 108, Irradiates the inside of the measurement object 109. FIG. 1A illustrates this state in detail. The light beam transmitted without being blocked by the light limiting slit 104 is, for example, between a dashed line 154 indicating the center of the light beam and a dotted line 152 indicating the outside of the light beam, and reflected by the mirror portion 108 a of the conical mirror 108. Further, a dotted line 152 indicating the outside of the light beam is reflected by the object to be measured 109 and again reflected by the conical mirror 108 toward the objective lens 107 as indicated by a solid line 153. That is, half of the light beam reflected and returned from the inside of the object to be measured 109 is still shielded, and is between the alternate long and short dash line 154 indicating the center of the light beam and the solid line 153 indicating the outside of the light beam.

  This will be described with reference to FIG. FIG. 4 is a diagram depicting the optical configuration of the hollow shape measuring apparatus 101 of FIG. 1, and the same reference numerals as those in FIG. 1 denote the same components. The light source system 102 includes a light source 120, an aperture stop 121 that determines the NA of illumination, a lens 122 that collects light from the light source 120, and an imaging stop 123 that determines the NA on the light receiving side. As described above, the light receiving surface of the imaging unit 111, the circular slit 103 constituting the field stop, and the area of the object 109 to be measured at the reference position are optically conjugate positions. It can be seen that the camera is in focus at several locations. In FIG. 4, since half of the light beam is shielded by the light limiting slit 104, half of the light beam returning from the object to be measured 109 is also shielded, and half of the light beam 160 indicated by hatching is not incident on the imaging unit 111. .

  Next, the effect of the filter 104b and the filter 104c will be described in detail with reference to FIGS. Actually, in FIG. 1, the telecentric optical system performs reduction or enlargement depending on the relationship between the size of the image sensor 111 and the DUT 109. Here, for ease of explanation, FIG. 5 and FIG. Is described as a telecentric optical system of the same magnification. By adopting the 1 × telecentric system, in FIG. 5 and FIG. 6, an image when the virtual screen 301 is placed at the focal position of the light beam projected from the light source system 102 and the focal position on the light receiving side (of the image sensor 111). The image projected onto the (imaging plane) becomes equal. That is, the size (width, length, etc.) of the image formed on the virtual screen 301 can be measured from the captured image of the image sensor 111. Hereinafter, the description will be made in the state of an image on the virtual screen 301.

  5 and 6 show the case where the inner surface 402 of the DUT 109 has an inclination of an angle θ with respect to the perpendicular 401. In particular, FIG. 5 shows a case where the inner surface position of the DUT 109 is larger than the reference dimension, and FIG. 6 shows a case where the inner surface position of the DUT 109 is smaller than the reference dimension. Further, the illumination NA of the light transmitted through the light limiting slit 104 is assumed to be known from the design value of the optical system. Therefore, the light projected through the light limiting slit 104 in FIG. 1 is irradiated on the inner surface of the measurement object 109 with an angle α from the line 152 to the line 154 by the illumination NA in FIGS. 5 and 6. The Here, the line 152 is the outer edge of the light beam corresponding to the dotted line 152 in FIG. 1, and the line 154 is the inner edge of the light beam corresponding to the one-dot chain line 154 in FIG. Further, as described in FIG. 2, the light flux between the line 154 and the line 155 is colored by the filter 104b by the filters 104b and 104c of the light limiting slit 104, and the light flux between the line 155 and the line 152. Is colored in the filter 104c. The line 155 is the illumination NA created by the filter 104b. The line 156 is a parallel line of the line 154, and the line 154 and the perpendicular 401 intersect at a right angle.

  In FIG. 5, since the inner surface 402 of the measured object 109 is inclined by the angle θ with respect to the normal 401, the light reflected from the point P <b> 2 on the inner surface 402 of the measured object 109 is reflected by the light beam from the normal position of the line 154. Projected to a position O 2 on the virtual screen 301. At this time, since the incident angle and the reflection angle at the point P2 are respectively equal to the angle θ, the angle formed by the line segment O0-P2 and the line segment O2-P2 is 2θ. Similarly, the light reflected from the angle of the line 152 at the point P 1 on the inner surface 402 of the object to be measured 109 is projected onto the position O 3 on the virtual screen 301. At this time, the inclination of the inner surface of the object 109 to be measured has a negative value for θ in FIG. 5 when the clockwise direction is positive with respect to the vertical line 401 and the counterclockwise direction is negative. Accordingly, since the incident angle and the reflection angle at the point P1 of the light ray from the angle of the line 152 can be written as an angle (α + θ), the angle formed by the line segment O0−P1 and the line segment O3−P1 is 2 (α + θ). Become. Since the angle formed between the line 154 and the line 156 that is a parallel line and the line segment O0-P1 is α, the angle formed between the line 156 and the line 153 ′ is α + 2θ.

  However, the relationship between the position O2 and the position O3 may not be determined depending on the value of the angle θ, the angle α, or the value of the deviation L from the reference dimension. For example, when the inner surface position of the object to be measured 109 is larger than the reference dimension as shown in FIG. 5 and when the inner surface position of the object to be measured 109 is smaller than the reference dimension as shown in FIG. The positional relationship between the image position O2 and the position O3 is upside down. For this reason, it is impossible to determine whether the both end positions of the image projected on the virtual screen 301 are due to the outer edge or the inner edge of the light beam transmitted through the light limiting slit 104.

  Therefore, in the hollow shape measuring apparatus 101 according to the present embodiment, since the light beam passing through the slit 104a of the light limiting slit 104 passes through the filter 104b and the filter 104c, the color of the image projected on the virtual screen 301 is detected. (Actually, by using an imaging device capable of discriminating colors such as a color camera in the imaging unit 111), it is possible to determine whether the light beam has passed through the outer edge or the inner edge of the light limiting slit 104. Become. As a result, it is possible to accurately distinguish the position O2 of the image of the light beam transmitted through the inner edge and the position O3 of the image of the light beam transmitted through the outer edge. The position detection of the positions O2 and O3 can be realized by performing image processing for edge detection on the image captured by the image sensor 111 by the image processing unit 112. For example, it is possible to differentiate the photographic image for each color of the filter 104b or the filter 104c, detect the peak thereof to obtain a light / dark boundary, and read the positions O2 and O3 from the coordinates of the imaging surface.

  The deviation L from the reference dimension of the inner surface position of the measured object 109 and the inclination θ of the inner surface of the measured object 109 based on the position O2 and the position O3 of the image obtained by the image processing and the angle α by the known illumination NA. , Θ, the actual measurement position ΔZ has the following relationship: In each equation, the values of O2 and O3 indicate the distances of the position O2 and the position O3 to the position O0. Further, in each of the following expressions, the inclination of the inner surface of the DUT 109 is positive in the clockwise direction with respect to the vertical line 401 and negative in the counterclockwise direction, and as described above, θ in FIG. Similarly, the displacement ΔL also has a negative value.

In FIG. 5, the value of O2 can be obtained from Equation 1.
O2 = (L-.DELTA.L) .tan (2.theta.) Equation 1
Further, the value of O3 can be obtained by Equation 2.
O 3 = L · tan (α + 2θ) + L · tan (α) Equation 2
Here, ΔZ can be expressed by Equation 3, and ΔL can be expressed by Equation 4 using Equation 3.
ΔZ = L · tan (α) Equation 3
ΔL = ΔZ · tan (θ) = L · tan (θ) · tan (α) Equation 4
Also, the values of L from Equation 2 can be obtained as in Equation 5.

L = O3 / (tan (α + 2θ) + tan (α)) Equation 5
As described above, since the values of O 2, O 3 and angle α are already known in the above equations 1, 4 and 5, solving the simultaneous equations of equations 1, 4 and 5, Three variables can be obtained: a deviation L from the reference position of the measured object 109, an inclination θ of the inner surface of the measured object 109, and a displacement ΔL. If the deviation amount L is known, the deviation amount ΔZ of the actual measurement position in the perpendicular direction (Z-axis direction) can be obtained from Equation 3. Note that the illumination NA value is calculated by using the calibration object to be measured having a known deviation L in the horizontal direction from the reference dimension and having no inclination of the inner surface as the object 109 to obtain the angle α from Equation 5. Can be sought. In addition, as described above, each of the above formulas shows a case of an equal magnification telecentric optical system, and an image projected on the actual imaging unit 111 is not necessarily an equal magnification. It is necessary to multiply by the corresponding coefficient.

  Similarly, even when the position of the inner surface of the object 109 to be measured shown in FIG. 6 is smaller than the reference dimension, Expressions 1 to 5 hold, so that the deviation L from the reference position of the object 109 to be measured, the object to be measured It is possible to obtain the inclination θ of the inner surface 109, the displacement ΔL, and the shift amount ΔZ of the measurement position in the Z-axis direction. In FIG. 6, the same reference numerals as those in FIG. 5 denote the same components. FIG. 6 differs from FIG. 5 in that the virtual screen 301 is located outside the inner surface 401 of the DUT 109.

  In FIG. 6, the inner surface 402 of the measured object 109 is inclined by the angle θ with respect to the perpendicular 401, so that the light beam from the normal position of the line 154 is reflected by the point P 3 on the inner surface 402 of the measured object 109 ( Line 154 ′) is equivalent to being projected at position O 2 on the virtual screen 301. Therefore, the angle formed by the line segment O0-P3 and the line segment O2-P3 is 2θ. Similarly, the light (line 153 ′) reflected by the point P 4 on the inner surface 402 of the object 109 to be measured from the angle of the line 152 is equivalent to being projected onto the position O 3 on the virtual screen 301. At this time, the inclination of the inner surface 402 of the DUT 109 comes from the direction of the line 152 since θ in FIG. 6 has a negative value when the clockwise direction is positive with respect to the vertical line 401 and the counterclockwise direction is negative. Since the incident angle and the reflection angle at the point P4 of the light ray to be written can be written as an angle (α + θ), the angle formed by the line segment O0−P4 and the line segment O3−P4 is 2 (α + θ). Since the angle formed by the line 154 and the line 156 that is a parallel line and the line segment O 0 -P 4 is α, the angle formed by the line 156 and the line 153 ′ is α + 2θ.

  In this manner, as in the case described with reference to FIG. 5, the same image as the virtual screen 301 can be taken by the imaging unit 111, and the position O 2 and the position O 3 can be obtained by the image processing unit 112. Further, since the angle α is known from the illumination NA, solving the simultaneous equations of Equations 1, 4 and 5, the deviation L from the reference position of the object 109 to be measured, the inclination θ of the inner surface of the object 109 to be measured, and the displacement Three variables of ΔL can be obtained. If the deviation amount L is known, the deviation amount ΔZ of the measurement position in the actual perpendicular 401 direction (Z-axis direction) can be obtained from Equation 3. Thereafter, the position of the inner surface 402 in the entire circumferential direction of the object to be measured 109 can be obtained by the method described with reference to FIGS. 5 and 6, and the inner shape of the object to be measured 109 at the Z-axis position can be measured. For example, FIG. 7 shows a case where the inner surface position of the object to be measured 109 is obtained every 45 degrees when the hole diameter of the object to be measured 109 is larger than the reference inner diameter (dotted line circle). Eight points (x marks) are obtained as the center position of the (shaded portion). Thereafter, the measurement error is eliminated from these points using a mathematical method such as a least square method, and the center of the object to be measured and the inner diameter of the object to be measured are calculated.

  Next, the image processing unit 112 sends a command to the Z-axis drive unit main body 113 connected via the cable 117 and moves the moving unit 114 holding the conical mirror 108 up and down at a predetermined pitch in the Z-axis direction. That is, the relative position between the measurement optical system and the conical mirror 108 is changed. Thereafter, similarly, image data is input from the imaging unit 111 at each predetermined position in the Z-axis direction of the moving unit 114, the input image data is processed, and the inner shape of the DUT 109 at the predetermined position in the Z-axis direction is processed. It is obtained for each position in the Z-axis direction.

  Next, an image of points constituting an image formed on the light receiving surface of the imaging unit 111 will be described with reference to FIG. FIG. 6A is a diagram showing a state when a certain point inside the object to be measured 109 is photographed by the imaging unit 111 when there is no light limiting slit 104, and in the case where the hole diameters are different at the measurement position. A change in the spread of the light beam, that is, a change in focus (blurred image) in the imaging unit 111 is depicted. Here, the focus is shifted depending on the inner diameter of the object 109 to be measured, but the inner diameter at the in-focus position is defined as the reference hole diameter, and the optical system of the hollow shape measuring apparatus 101 is preliminarily adjusted so that the focus is exactly at this reference hole diameter. It shall be calibrated.

  451 and 451a to 451f in FIG. 5A show images picked up by the image pickup unit 111, where the portion indicated by the straight line 401 is the reference hole diameter, and the hole diameter from the straight line 401 toward the upper side of the paper surface. On the contrary, the hole diameter decreases toward the lower side of the drawing. For example, when the reference hole diameter is photographed, the image is not blurred as the light beam 451, but the light beam spreads as the light beams 451a, 451b, and 451c as the hole diameter becomes larger than the reference hole diameter. Similarly, as the hole diameter becomes smaller than the reference hole diameter, the light beam spreads as light beams 451d, 451e, and 451f. That is, the magnitude of deviation from the reference hole diameter can be measured from the amount of spread of the light beam. However, at this time, the light beam spreads in the same way on both sides of the axis C4 passing through the focus position of the reference hole diameter regardless of whether the hole diameter increases or decreases. Cannot determine whether it has become smaller or smaller.

  On the other hand, in the case of the present embodiment, half of the light beam irradiated to the object to be measured 109 is shielded by the light limiting slit 104, so the change in the spread of the light beam when the hole diameter is different is shown in FIG. become that way. In the figure, when the reference hole diameter is photographed, the image is not blurred as the light beam 452, but as the hole diameter becomes larger than the reference hole diameter, along the dotted line C5 as the light beams 452a, 452b and 452c. The luminous flux spreads. Similarly, as the hole diameter becomes smaller than the reference hole diameter, the light beam spreads along the dotted line C5 as light beams 452d, 452e and 452f. However, unlike the case of FIG. 8A, the light beams 452a, 452b and 452c are spread only in the direction of the dotted line C5 on the right side of the axis C4, and similarly, the light beams 452d, 452e and 452f. Is spread only in the direction of the dotted line C5 on the left side of the paper surface of the axis C4. That is, it is possible to determine whether the hole diameter of the DUT 109 is larger or smaller than the reference hole diameter depending on whether the dotted line C5 extends to the right or left from the axis C4. The image processing unit 112 measures the magnitude of the deviation from the reference hole diameter from the determination result and the amount of spread of the light beam, and determines how large or small the inner shape of the DUT 109 is with respect to the reference hole diameter. Can be sought.

  Although the state of the light beam imaged on the light receiving surface of the imaging unit 111 has been described with reference to FIG. 8, FIG. 8 illustrates a case where the inclination θ of the inner surface of the DUT 109 is zero. As described above with reference to FIGS. 5 and 6, when the inclination θ of the inner surface of the DUT 109 is not 0, an image is formed on the light receiving surface of the imaging unit 111 as illustrated in FIG. 9. 9A corresponds to the drawing of FIG. 8B when θ is negative, and FIG. 9B corresponds to the drawing of FIG. 8B when θ is positive. In FIG. 9, the same reference numerals as those in FIG. 8 indicate the same components. When θ is 0, the width corresponding to the hole diameter is formed in the portion sandwiched between the dashed line C4 and the dotted line C5 as in FIG. The statue spreads. On the other hand, when θ in FIG. 9A is negative, the image spreads in a portion sandwiched between the solid line C2 and the solid line C3. Similarly, when θ in FIG. 9B is positive, the image spreads in a portion sandwiched between the solid line C2 'and the solid line C3'. As in the case where θ is 0, the image spreads in the right direction with reference to solid line C2 or solid line C2 ′ when the hole diameter is large, and solid line C2 or solid line C2 when the hole diameter is small. The image spreads to the left with 'as the reference. In this way, when the image processing unit 112 receives the image data imaged on the light receiving surface of the imaging unit 111, whether the inner shape of the DUT 109 is larger or smaller than the reference hole diameter from the direction in which the light beam spreads. Can be determined.

Next, the measurement flow of the hollow shape measuring apparatus 101 will be described with reference to the flowchart of FIG.
(Step S201) First, the DUT 109 is set under the moving unit 114.
(Step S202) Next, measurement specifications such as a measurement range (movement range) in the Z-axis direction and a measurement pitch (movement pitch) in the Z-axis direction of the moving unit 114 are input from the personal computer 115. The measurement specification input by the personal computer 115 is output to the image processing unit 112 via the cable 118, and the image processing unit 112 moves the moving unit 114 to the measurement start position on the Z-axis drive unit main body 113 via the cable 117. Command.
(Step S <b> 203) Light is emitted from the light source system 102 at the current position of the moving unit 114, and an image is captured by the imaging unit 111.
(Step S <b> 204) The image received by the imaging unit 111 is output to the image processing unit 112 via the cable 116.
(Step S205) The image processing unit 112 obtains the inner diameter (shape) of the DUT 109. At this time, as described with reference to FIGS. 5 and 6, the inner diameter obtained by correcting the error due to the inclination θ of the inner surface of the DUT 109 is obtained.
(Step S206) It is determined whether the measurement is completed according to the measurement specification. For example, if the moving unit 114 has not reached the end position of the set movement range in the Z-axis direction, the process proceeds to step S207, and if it has reached the end position, the process proceeds to step S208.
(Step S207) According to the set measurement pitch in the Z-axis direction, the moving unit 114 moves to the next measurement position in the Z-axis direction, returns to Step S203, and performs measurement at the position.
(Step S208) When the movement unit 114 reaches the end position of the set movement range in the Z-axis direction and finishes the measurement, the inner height of the object to be measured 109 (relative position with respect to the measurement optical system) Shapes are obtained, and these shapes are synthesized to create hollow shape data.

  Here, a method of creating hollow shape data will be described with reference to FIG. In the figure, reference numerals 701 to 706 denote inner shapes when the height is varied from the height (n) to (n + 5) for each predetermined pitch in the Z-axis direction (height direction). In the drawing, the inner shape is shown as a circle for easy understanding. However, depending on the object to be measured 109, the shape has irregularities with different radii. Further, since the position shift of ΔZ occurs at each point due to the inclination of the surface, the hollow shape data of the object to be measured 109 is obtained by synthesizing the inner shapes 701 to 706 with ΔZ taken into account for each height. The three-dimensional hollow shape 109a can be constructed from the hollow shape data. In addition, it is preferable that the center of the measurement light coincides with the center of the object to be measured 109 at the time of measurement.

Now, returning to the flowchart of FIG.
(Step S209) The hollow shape data created by the image processing unit 112 is output to the personal computer 115 via the cable 118 and displayed on the screen of the personal computer 115.
(Step S210) If necessary, the personal computer 115 operates the keyboard or mouse to specify an arbitrary position of the device 109 displayed on the screen, and the device under test received from the image processing unit 112. The size and length of each part designated from 109 hollow shape data are displayed.
(Step S211) All measurements are terminated.

  In this way, by extracting the inner shape of the portion where the light hits the object to be measured while moving the moving unit 114 up and down in the Z-axis direction at a predetermined pitch, and synthesizing these as the inner shape for each predetermined position, The hollow shape of the DUT 109 can be measured. The measured hollow shape data of the measured object 109 is sent to the personal computer 115 via the cable 118, and the personal computer 115 can display the hollow shape data of the measured object 109.

  In particular, in this embodiment, even when the inner surface 402 of the hollow cylindrical object 109 is inclined, the shift amount ΔZ is corrected according to the inclination θ, so that the inner shape of the object 109 is increased. It can be measured with accuracy.

(Second Embodiment)
Next, a second embodiment will be described. The hollow shape measuring apparatus 101 according to the present embodiment has basically the same structure as the hollow shape measuring apparatus 101 according to the first embodiment shown in FIG. 1, but the light limiting slit 104 is different. In the present embodiment, for example, the light limiting slit 104 ′ shown in FIGS. 12B and 12C is used instead of the light limiting slit 104 of FIG. 2 of the first embodiment. FIG. 12A shows the same circular slit 103 as FIG. Here, an alternate long and short dash line 154 in FIGS. 1 and 12 indicates the center position of the ring-shaped light beam.

  The feature of the light limiting slit 104 'in this embodiment is that the slit width can be varied concentrically. FIG. 12B shows a case where the slit width is narrowed, and FIG. 12C shows a case where the slit width is widened.

  The light limiting slit 104 ′ in the case of FIG. 12B is provided with a ring-shaped slit 104 ′ d that shields half of the light beam transmitted through the circular slit 103 and transmits the remaining half. The feature of the light limiting slit 104 ′ is that the inner diameter of the ring-shaped slit 104′d corresponds to the position of the alternate long and short dash line 154 indicating the center position of the ring-shaped light beam as indicated by the one-dot chain lines C2 and C3. The ring-shaped slit 104′d transmits only a part of the outside of the light beam.

  Similarly, the light limiting slit 104 ′ in the case of FIG. 12C is provided with a ring-shaped slit 104 ′ e that shields half of the light beam transmitted through the circular slit 103 and transmits the remaining half. In the light limiting slit 104 ′ in FIG. 12C, the inner diameter of the ring-shaped slit 104′e is equal to the inner diameter of the ring-shaped slit 104′d in FIG. Although not changed, the outer edges C11 and C12 of the ring-shaped slit 104′e are wider than the outer edges C9 and C10 of the ring-shaped slit 104′d of FIG.

  In this way, the position of the outer edge of the light beam passing through the light limiting slit 104 'can be varied. As a method for changing the slit width of the light limiting slit 104 ', for example, the structure of a camera diaphragm can be applied. By providing such a movable part in the light restricting slit 104 ′ and controlling the movable part of the light restricting slit 104 ′ from the image processing unit 112 or the personal computer 115, the slit width of the light restricting slit 104 ′ can be arbitrarily set during measurement. Can be variable.

  Next, the measuring method of the hollow shape measuring apparatus 101 according to the present embodiment will be described. Also in this embodiment, in the same manner as the measurement method described in FIGS. 5 and 6 of the first embodiment, the deviation L from the reference position of the object 109 to be measured, the inclination θ of the inner surface of the object 109 to be measured. , Displacement ΔL, displacement amount ΔZ of the measurement position in the Z-axis direction can be obtained.

  However, in the first embodiment, the position O2 and the position O3 in FIGS. 5 and 6 are distinguished by the filter 104b and the filter 104c provided in the light limiting slit 104, but in the present embodiment, description will be given with reference to FIG. The position O2 and the position O3 are distinguished by the light limiting slit 104 '. In the hollow shape measuring apparatus 101 according to this embodiment, the light limiting slit 104 ′ can narrow or widen the position of the outer edge of the light beam during measurement. For example, in FIG. Is expanded or narrowed with respect to the line 154. As a result, the position O 3 projected on the virtual screen 301 moves on the virtual screen 301. The image processing unit 112 analyzes the image input from the imaging unit 111 and identifies the moving edge as the position O3. On the contrary, it can be seen that the edge not moving is O2. Also in FIG. 6, it is possible to identify the moving edge as the position O3 and the non-moving edge as the position O2.

  If the position O2 and the position O3 can be obtained, the deviation L from the reference position of the object 109 to be measured, the measured object 109 from the simultaneous equations of Expressions 1, 4 and 5 as in the first embodiment. The three variables of the inner surface inclination θ and displacement ΔL can be obtained. Further, the deviation amount ΔZ of the measurement position in the Z-axis direction can also be obtained from Equation 3.

  Since processing other than the above is the same as that of the flowchart of FIG. 10 of the first embodiment, redundant description is omitted.

  In this way, by extracting the inner shape of the portion where the light hits the object to be measured while moving the moving unit 114 up and down in the Z-axis direction at a predetermined pitch, and synthesizing these as the inner shape for each predetermined position, The hollow shape of the DUT 109 can be measured. The measured hollow shape data of the measured object 109 is sent to the personal computer 115 via the cable 118, and the personal computer 115 can display the hollow shape data of the measured object 109.

  In particular, in this embodiment, since the position of the outer edge of the light limiting slit 104 ′ is variable, the outer edge and the inner edge of the light flux that has passed through the slit of the light limiting slit 104 ′ are displayed in the image input from the imaging unit 111. It becomes possible to easily discriminate. As a result, even when the inner surface 402 of the hollow cylindrical object 109 is inclined, the shift amount ΔZ is corrected according to the inclination θ, so that the inner shape of the object 109 is measured with high accuracy. be able to.

(Third embodiment)
Next, a third embodiment will be described with reference to FIG. The hollow shape measuring apparatus 101 according to the present embodiment has basically the same structure as the hollow shape measuring apparatus 101 according to the first embodiment shown in FIG. 1, but the arrangement of the imaging unit 111 is different. Although the imaging unit 111 of the first embodiment is optically conjugate with the reference position where the object 109 is set, the imaging unit 111 ′ of the hollow shape measuring apparatus 101 ′ according to the present embodiment is The reference object 109 is placed at a position translated parallel to the reference position and the optical conjugate position.

  For this reason, as shown in FIGS. 14 and 15, the inner surface shape of the DUT 109 can be obtained. 14 corresponds to FIG. 5 of the first embodiment, showing a case where the inner surface position of the DUT 109 is larger than the reference dimension, and FIG. 15 corresponds to FIG. 6 of the first embodiment. The case where the inner surface position of the DUT 109 is smaller than the reference dimension is shown. 5 and 6 denote the same components. 14 and 15, the difference from FIGS. 5 and 6 is the position of the virtual screen 302, which is shifted from the position of the virtual screen 301 by ΔX. This is because, as described above, the position of the imaging unit 111 ′ is shifted from the position of the imaging unit 111. Due to the deviation ΔX of the virtual screen, the positions at which the positions O2 and O3 are projected are shifted to the positions O2 'and O3'.

  Next, the shift amount L from the reference position of the object 109 to be measured from the position O2 ′ and the position O3 ′, the inclination θ of the inner surface 402 of the measured object 109, the displacement ΔL, and the shift amount ΔZ of the measurement position in the Z-axis direction are obtained. Will be explained.

  The deviation L of the inner surface position of the measured object 109 from the reference dimension, the inner surface position of the measured object 109, based on the position O2 ′ and position O3 ′ of the image obtained by the image processing and the angle α by the known illumination NA. The shift amount ΔZ of the measurement position due to the inclinations θ and θ has the following relationship. In each equation, the values of O2 'and O3' indicate the distance between the position O2 'and the position O3' with respect to the position O0 '. In the following equations, the inclination of the inner surface 402 of the DUT 109 is positive in the clockwise direction with respect to the normal 401 and negative in the counterclockwise direction, and therefore θ in FIG. 5 has a negative value. Similarly, the displacement ΔL has a negative value. ΔX also has a negative value.

In FIG. 14, the value of O2 ′ can be obtained from Equation 6.
O2 '= (L-.DELTA.L + .DELTA.X) .tan (2.theta.) Equation 6
Further, the value of O3 ′ can be obtained by Expression 7.
O3 ′ = (L + ΔX) · tan (α + 2θ) + (L + ΔX) · tan (α) Equation 7
Here, ΔZ can be expressed by Equation 8, and ΔL can be expressed by Equation 9 using Equation 8.
ΔZ = L · tan (α) Equation 8
ΔL = ΔZ · tan (θ) = L · tan (θ) · tan (α) Equation 9
Further, the values of L from Equations 7 can be obtained as in Equation 10.
L = O3 ′ / (tan (α + 2θ) + tan (α)) Equation 10
In the above Equation 6, Equation 9, and Equation 10, since the values of O2 ′, O3 ′, and angle α are known, solving the simultaneous equations of Equation 6, Equation 9, and Equation 10 provides a reference for the object 109 to be measured. Three variables can be obtained: a deviation amount L from the position, an inclination θ of the inner surface of the measured object 109, and a displacement ΔL. If the deviation amount L is known, the deviation amount ΔZ of the actual measurement position in the perpendicular direction (Z-axis direction) can be obtained from Equation 8. Note that the value of the illumination NA is calculated by using the calibration object to be measured having a known deviation L in the horizontal direction from the reference dimension and having no inner surface tilt as the object to be measured 109. Can be obtained as In addition, each of the above formulas shows a case of an equal magnification telecentric optical system, and an actual image projected on the imaging unit 111 ′ is not necessarily an equal magnification, so it is necessary to multiply by a coefficient corresponding to an enlargement ratio or a reduction ratio. There is.

Here, when the position of the inner surface of the object to be measured 109 is equal to the reference position, that is, when L = 0, the position O3 cannot be specified by the equations 1 to 5 described in the first embodiment, so Although the inclination θ of the inner surface cannot be obtained, in the case of the present embodiment, it can be calculated as follows.
O2 '= ΔX · tan (2θ)
O3 ′ = ΔX · tan (2θ + α) + ΔX · tan (α)
Thus, the value of O2 ′ and the value of O3 ′ can be calculated.

Also, when L = ΔX, from Equation 6 and Equation 7,
O3 '= 0
O2 ′ = − ΔL · tan (2θ)
= L · tan (θ) · tan (α) · L · tan (2θ)
= ΔX · tan (θ) · tan (α) · L · tan (2θ)
Thus, the value of O2 ′ and the value of O3 ′ can be calculated.

  In this way, the deviation amount L from the reference position of the DUT 109, the inclination θ of the inner surface of the DUT 109, the displacement ΔL, and the deviation ΔZ of the measurement position in the Z-axis direction can be obtained.

  The measuring method of the hollow shape measuring apparatus 101 ′ according to the present embodiment is basically the same as the flowchart of FIG. 10 of the first embodiment, but the inclination θ of the inner surface of the DUT 109 is obtained in step S205. The processing at this time is different, and the inclination θ is obtained by the method described with reference to FIGS. Since other processes are the same as those in the first embodiment, a duplicate description is omitted.

  In this way, the inner shape of the portion where the light hits the object to be measured is accurately extracted while moving the moving unit 114 up and down in the Z-axis direction at a predetermined pitch, and these are synthesized as the inner shape for each predetermined position. Thus, the hollow shape of the DUT 109 can be measured. The measured hollow shape data of the measured object 109 is sent to the personal computer 115 via the cable 118, and the personal computer 115 can display the hollow shape data of the measured object 109. In particular, in the present embodiment, the inclination θ of the inner surface 402 of the object to be measured 109 can be obtained even when the position of the inner surface of the object to be measured 109 is equal to the reference position, that is, when L = 0, so that the object to be measured can be measured more accurately. The hollow shape of the object 109 can be measured. Note that the same processing can be performed even if the imaging unit 111 ′ is translated downward from the conjugate position optically with respect to the reference position.

  As described above, in each embodiment, the hollow shape measuring apparatus 101 of the present invention obtains the inner shape from the deviation from the reference hole diameter for each predetermined height of the hollow cylindrical object, and the height is variable. The hollow shape of the object can be three-dimensionally constructed by synthesizing the inner shape for each predetermined position measured. In particular, since the inner shape is obtained from the deviation from the reference hole diameter, it is not necessary to perform complicated calculations with a simple configuration. Further, the moire method for obtaining all the contour lines at once has a problem that an error becomes large due to the difference in height of the object. However, in the hollow shape measuring apparatus and the measuring method according to the present embodiment, the inner shape is obtained for each height. Therefore, highly accurate measurement is possible regardless of the height difference of the object. Further, since the inner shape over the entire circumference can be obtained by one imaging, three-dimensional measurement can be performed at a very high speed as compared with the conventional palpation-type three-dimensional measurement.

  In the first and third embodiments, the light limiting slit 104 is configured by a color filter, and in the second embodiment, the light limiting slit 104 ′ is used for mechanically changing the outer edge. For example, the light limiting slit is formed of a liquid crystal element and the outer edge side (first edge side) and the inner edge side (second edge side) are differently modulated. It is clear that the same effect as the above-described embodiment can be obtained even if time modulation is applied by changing the opening timing between the edge and the inner edge.

  In each embodiment, the image processing unit 112 that performs image processing and the personal computer 115 that displays the entire operation of the hollow shape measuring apparatus 101 and the measurement results are separately provided. You may make it incorporate hardware and software. Or, conversely, an operation unit or a display unit may be provided in the image processing unit 112 to be a control unit dedicated to the hollow shape measuring apparatus 101.

It is a lineblock diagram of hollow shape measuring device 101 concerning a 1st embodiment. It is a block diagram of the circular slit 103 and the light limiting slit 104 of the hollow shape measuring apparatus 101. 2 is a configuration diagram of a conical mirror 108 of the hollow shape measuring apparatus 101. FIG. 3 is an auxiliary diagram showing an optical system of the hollow shape measuring apparatus 101. FIG. It is an auxiliary figure for demonstrating a measurement principle. It is an auxiliary figure for demonstrating a measurement principle. It is an auxiliary figure for demonstrating a measurement principle. It is an auxiliary figure for demonstrating a hole diameter and the breadth of an image. It is an auxiliary figure for demonstrating a hole diameter and the breadth of an image. It is a flowchart which shows the measurement procedure of the hollow shape measuring apparatus 101. FIG. It is an auxiliary figure for demonstrating construction of a hollow shape. It is an auxiliary figure for explaining light limiting slit 104 'of hollow shape measuring device 101 concerning a 2nd embodiment. It is a block diagram of the hollow shape measuring apparatus 101 'which concerns on 3rd Embodiment. It is an auxiliary figure for demonstrating a measurement principle. It is an auxiliary figure for demonstrating a measurement principle.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 ... Hollow shape measuring apparatus; 102 ... Light source system; 103 ... Circular slit; 104 ... Light restricting slit; 105 ... Illumination lens; 106 ... Half mirror; 108: Conical mirror; 109 ... Object to be measured; 110 ... Imaging lens; 111 ... Imaging unit; 112 ... Image processing unit; 113 ... Z-axis drive unit body 114: moving unit; 115 ... personal computer

Claims (14)

A measuring device for measuring the inner shape of a hollow cylindrical object to be measured,
A light transmitting section for transmitting light in a first direction which is the axial direction of the hollow cylinder;
A converter that converts the traveling direction of the light into a direction substantially orthogonal to the first direction;
A modulation unit that applies physical modulation so that the light converted by the conversion unit is distinguishable in the first direction;
A detection unit for detecting focusing information of the light reflected inside the object to be measured and light information of the physical modulation among the light whose direction is converted by the conversion unit;
A measuring apparatus comprising: a shape measuring unit that measures an inner shape of the object to be measured by obtaining a deviation from a predetermined reference position based on a detection result of the detecting unit. The measuring apparatus according to claim 1,
The detection unit is capable of detecting a first edge position that is one end and a second edge position that is the other end in the first direction of the light subjected to the physical modulation. Measuring device. In the measuring apparatus according to claim 1 or 2,
A moving unit that relatively moves the conversion unit and the object to be measured in the first direction;
The shape measuring unit measures an inner shape of the measurement object at a plurality of relative positions with the conversion unit and the measurement object. In the measuring device according to any one of claims 1 to 3,
The light transmission unit includes: a light source that generates the light; a first optical system that guides light from the light source and has a focal point at a reference position; and the light source side of the first optical system with respect to the focal point. A first light limiting member disposed at a position conjugate with the focal point and having an opening of a predetermined shape;
A second optical system for imaging the light returned from the object to be measured,
The detection unit is disposed on a non-imaging plane that is translated in the optical axis direction from an imaging plane on which an image of the object to be measured at the reference position is formed by the second optical system, and detects light from the light source. A measuring apparatus, comprising: a light receiving unit having a conjugate relationship with the reference position for receiving light. The measuring apparatus according to claim 4, wherein
A measuring apparatus, comprising: a second light limiting member having an opening having a predetermined shape that blocks a part of a light beam irradiated to the object to be measured from the first light limiting member. The measuring apparatus according to claim 5, wherein
A measuring apparatus comprising: a color filter that performs different modulation on the first edge side and the second edge side of both ends of the light beam transmitted through the second light limiting member. The measuring apparatus according to claim 5, wherein
A shape variable mechanism for arbitrarily changing at least one edge shape of the first edge side and the second edge side of both ends of the light beam passing through the second light limiting member into a concentric shape is provided. apparatus. The measuring apparatus according to claim 6, wherein
The detection unit detects the first edge position and the second edge position by performing color detection of a light beam that is projected when the light beam that has passed through the color filter is reflected inside the object to be measured. Characteristic measuring device. In the measuring device according to any one of claims 1 to 8,
The light transmitting unit is disposed at a position for transmitting light from a direction different from the first direction,
Reflecting the light transmitted by the light transmitting unit in the first direction between the measured object and the light transmitting unit, and returning light returning from the measured object to the light receiving unit side A measuring device characterized in that a half mirror is provided. In the measuring device according to any one of claims 1 to 9,
The measuring device is characterized in that the conversion unit is constituted by a conical mirror. In the measuring device according to any one of claims 1 to 10,
The first light limiting member is configured by a circular slit. A measuring method for measuring the inner shape of a hollow cylindrical object to be measured,
The light transmitting unit converts the light transmitted in the first direction which is the axial direction of the hollow cylindrical shape, the traveling direction of the light is converted into a direction substantially orthogonal to the first direction, and the traveling direction is converted The light is physically modulated in the first direction by the modulation unit so as to be distinguishable, and the focusing information of the light reflected on the inside of the object to be measured among the light subjected to the physical modulation and the physical A measurement method comprising measuring an inner shape of the object to be measured by obtaining a deviation from a predetermined reference position based on a detection result obtained by detecting a modulation information by a detection unit. The measurement method according to claim 12, wherein
A measurement method comprising: detecting a first edge position which is one end portion and a second edge position which is the other end portion in the first direction of the light subjected to the physical modulation. The measurement method according to claim 12 or claim 13,
Performing the detection while relatively moving the conversion unit and the device under test in the first direction, and measuring an inner shape of the device under measurement at a plurality of relative positions with the conversion unit and the device under test. Measuring method characterized by

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