JP2013104673A - Apparatus and method for measuring x-ray diffraction - Google Patents

Abstract

PROBLEM TO BE SOLVED: To highly accurately measure a residual stress of a measuring object despite mounting accuracy of an imaging plate.SOLUTION: A controller CT irradiates a reference object BOB whose residual stress is 0 and a measuring object with X rays from an X-ray emitter 13 to capture diffraction rings of the reference object BOB and the measuring object OB on an imaging plate 28. The controller CT detects the shapes of both the captured diffraction rings respectively, calibrates the shape of the diffraction ring of the measuring object OB using the shape of the diffraction ring of the reference object BOB, and reduces the influence of a mounting error of the imaging plate 28 with respect to a table 27.

Description

  In the present invention, in order to measure the residual stress of a measurement object, the measurement object is irradiated with X-rays, and the shape of a diffraction ring formed on the surface of the imaging plate is measured by X-rays diffracted by the measurement object. The present invention relates to an X-ray diffraction measurement apparatus and an X-ray diffraction measurement method.

  Conventionally, the residual stress of a measurement object is often measured by X-ray diffraction. In the X-ray diffraction measurement apparatus, there is an apparatus disclosed in Patent Document 1 below as an apparatus that can be downsized and can shorten the X-ray irradiation time. This device irradiates a measurement object with X-rays at a predetermined angle, receives X-rays diffracted by the measurement object (hereinafter referred to as diffraction X-rays) with a photosensitive imaging plate, and forms them on the imaging plate. The shape of the formed circular X-ray diffraction image (hereinafter referred to as a diffraction ring) is measured. Then, the shape of the measured diffraction ring is analyzed by the cos α method, and the residual stress of the measurement object is calculated.

  Japanese Patent Application Laid-Open No. 2004-259561 also discloses a method of receiving diffracted X-rays with an X-ray CCD instead of an imaging plate and obtaining a diffraction ring shape from a signal output from each pixel of the X-ray CCD. In order to reduce the cost of the apparatus, a method of forming a diffraction ring on the imaging plate and detecting the shape of the formed diffraction ring is mainly used. This detection method is a method in which an imaging plate is scanned with excitation light such as a He-Ne laser, and the intensity of light generated by stimulated emission from the diffraction ring is amplified and detected by a photoelectron tube to obtain an image of the diffraction ring. is there.

JP-A-2005-241308

  If the imaging plate is mounted so that the normal direction coincides with the X-ray irradiation direction as shown in Patent Document 1, an object having a residual stress of “0” (for example, iron powder is applied to the object) The diffraction ring formed by the diffracted X-rays is a perfect circle, and the center of the circle is the point where the optical axis of the emitted X-ray intersects the imaging plate. Since the diffraction ring formed by the measurement object having the residual stress deviates from a perfect circle, the residual stress can be calculated from the shape of the diffraction ring. However, the inventor measured the diffraction ring of the object having a residual stress of “0” several times while attaching and removing the imaging plate. I found out that As exaggeratedly shown in FIG. 18A, the normal direction of the imaging plate does not coincide with the X-ray irradiation direction. That is, it is thought that this is because the imaging plate is attached at an inclination or the attached imaging plate is distorted.

  That is, if the diffracted X-ray generated from the X-ray irradiation point of the measurement object is a residual stress of “0”, any direction proceeds along the side surface of the cone, so the normal direction of the imaging plate is the X-ray irradiation direction. If they coincide with each other, a diffraction ring having the same shape as the cross section when the cone is cut along a plane parallel to the bottom surface is formed, and becomes a perfect circle as shown by a solid line X1 in FIG. However, when the imaging plate is mounted with an inclination, a diffraction ring having the same shape as the cross section when the cone is cut along a plane that is not parallel to the bottom surface is formed, and becomes an ellipse as indicated by a broken line X2 in FIG. Become. When the imaging plate is distorted, a diffractive ring having the same shape as the cross section when the cone is cut by the distorted surface is formed, and becomes a distorted circle as indicated by a dotted line X3 in FIG. As a result, if the imaging plate is mounted so that the normal direction thereof is accurately aligned with the X-ray irradiation direction, the measurement accuracy of the residual stress based on the measured diffraction ring will be good. Has a problem that the measurement accuracy deteriorates. In addition, the rotation center of the imaging plate may deviate from the optical axis of the outgoing X-ray, and this deviation further deteriorates the measurement accuracy of the residual stress based on the measured diffraction ring.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an X-ray diffractometer and an X-ray diffractometer that can accurately measure residual stress regardless of whether the imaging plate is attached accurately. It is to provide a measurement method. In the description of each constituent element of the present invention below, in order to facilitate understanding of the present invention, reference numerals of corresponding portions of the embodiments described later are shown in parentheses, but each constituent element of the present invention is described. Should not be construed as limited to the configuration of the corresponding parts indicated by the reference numerals of this embodiment.

  In order to achieve the above object, the present invention is characterized by an X-ray emitter (13) that emits X-rays toward a target object, and a table in which a through-hole that allows X-rays to pass through is formed in the center ( 27), an imaging plate (28) which is attached to a table and has a light receiving surface for receiving X-ray diffracted light diffracted by an object, records a diffraction ring which is an image of the diffracted light, and laser light. It has a laser light source that emits light and a photodetector that receives the laser light, and irradiates the light receiving surface of the imaging plate with the laser light, and also receives the light emitted from the imaging plate by the laser light irradiation and receives light according to the light receiving intensity A laser detection device (PUH) that outputs a signal, a rotating means (24, 25) for rotating the table around the central axis of the through-hole, and rotation of the table by the rotating means Rotation angle detection means (26) for detecting the rotation angle from the quasi-position and movement means (15, 17,...) For moving the table relative to the laser detection device in a direction parallel to the light receiving surface of the imaging plate. 18, 22), a moving position detecting means (21) for detecting the moving position of the table by the moving means, and a table in which the table is moved by controlling the moving means, and the residual stress is “0” from the X-ray emitter. First diffraction ring imaging means (CT, S102, S110, S200 to S226) that irradiates an object (BOB) with X-rays and images the diffraction ring of the reference object on the imaging plate by X-rays diffracted by the reference object S600 to S614), and the rotation means and the movement means are controlled to rotate and move the imaging plate on which the diffractive ring of the reference object is recorded. Rotate the irradiation position of the laser beam on the imaging plate around the center of the imaging plate and change it in the radial direction. The received light intensity data representing the received light intensity is sequentially read in association with the irradiation position on the imaging plate of the laser light acquired from the rotation position detected by the rotation angle detection means and the movement position detected by the movement position detection means, First diffraction ring shape detecting means (CT, S104, S112, S300 to S350, S400 to S420, S700 to S750) for detecting the shape of the diffraction ring of the reference object formed on the imaging plate based on the read light intensity data. And control the moving means table , Irradiates the measurement object (OB) with X-rays from the X-ray emitter, and images the diffraction ring of the measurement object on the imaging plate by the X-ray diffracted by the measurement object Laser light emitted from the laser detection device by controlling the imaging means (CT, S802, S200 to S226) and the rotating means and moving means to rotate and move the imaging plate on which the diffraction ring of the measurement object is recorded. While rotating the irradiation position on the imaging plate around the center of the imaging plate and changing it in the radial direction, each of the received light signals output from the laser detector is input, and the received light intensity expressed by the input received light signal is calculated. The received light intensity data representing the rotation position detected by the rotation angle detection means and the movement position detection means A second diffraction ring for sequentially reading the laser light acquired from the moving position in association with the irradiation position on the imaging plate, and detecting the shape of the diffraction ring of the measurement object formed on the imaging plate based on the read received light intensity data The shape of the diffraction ring of the measurement object detected by the shape detection means (CT, S804, S300 to S350, S400 to S420) and the second diffraction ring shape detection means was detected by the first diffraction ring shape detection means. Correction means (CT, S106, S114, S118, S302, S808, S810) for correcting by using the shape of the diffraction ring of the reference object and reducing the influence of the mounting error on the imaging plate table is provided. .

  In the present invention configured as described above, the first diffraction ring shape detecting means diffracts the reference object formed on the imaging plate by irradiating the reference object with a residual stress of “0” with X-rays. Detect the shape of the ring. On the other hand, in the state where the normal direction of the imaging plate coincides with the X-ray emission direction and the rotation center of the imaging plate coincides with the X-ray emission point, X-rays are applied to the reference object having no residual stress. , A perfect circular diffractive ring at the X-ray emission position and centering on the rotation center of the imaging plate should be formed on the imaging plate. Therefore, the difference in the shape of the diffraction ring detected by the first diffraction ring shape detection means with respect to the perfect circular diffraction ring is that the normal direction of the imaging plate does not exactly match the X-ray emission direction or is attached. This represents a shift when the imaging plate is distorted, that is, a shift when the imaging plate is not properly attached to the table. The correction means corrects the shape of the diffraction ring of the measurement object detected by the second diffraction ring shape detection means by using the shape of the diffraction ring of the reference object detected by the first diffraction ring shape detection means. This reduces the influence of mounting errors on the imaging plate table. As a result, according to the present invention, the shape of the diffraction ring of the measurement object is accurately corrected and the residual stress of the measurement object can be accurately measured even if the imaging plate is not properly attached to the table. Become.

  In the above feature of the present invention, for example, the first diffractive ring imaging means controls the rotation means using the rotation angle detected by the rotation angle detection means, rotates the table, and sets the imaging plate at a predetermined angular position. The second diffractive ring imaging means controls the rotation means by using the rotation angle detected by the rotation angle detection means, rotates the table, and the imaging plate has a first angle position setting means (S102, S202). Is set at the same angular position as the predetermined angular position by the first angular position setting means (S802, S202), and the diffraction ring of the reference object detected by the first diffraction ring shape detection means is included. The shape is represented by the distance from the rotation center of the imaging plate for each predetermined angle, and the measurement object detected by the second diffraction ring shape detection means The shape of the diffraction ring is expressed by the distance from the rotation center of the imaging plate for each predetermined angle, and the correction means is applied to the imaging plate when the normal direction of the imaging plate coincides with the X-ray emission direction. Using the ratio of the radius of the diffraction ring consisting of a perfect circle of the reference object to be imaged and the distance from the rotation center of the imaging plate at a predetermined angle that represents the shape of the diffraction ring of the reference object, the diffraction ring of the object to be measured is used. The distance from the rotation center of the imaging plate for each predetermined angle representing the shape of the imaging plate is corrected, and when the normal direction of the imaging plate coincides with the X-ray emission direction, the measurement object imaged on the imaging plate First correction means (S810) for calculating the distance from the rotation center of the imaging plate for each predetermined angle representing the shape of the diffraction ring.

  In this case, when the normal direction of the imaging plate coincides with the X-ray emission direction, the image is picked up by the first diffraction ring imaging means and the radius of the diffraction ring made of a perfect circle of the reference object imaged on the imaging plate. The ratio of the distance from the center of rotation of the imaging plate for each predetermined angle that represents the shape of the diffraction ring of the reference object is imaged on the imaging plate when the normal direction of the imaging plate matches the X-ray emission direction. The distance from the rotation center of the imaging plate for each predetermined angle representing the shape of the diffraction ring of the measurement object to be measured, and for each predetermined angle representing the shape of the diffraction ring of the measurement object imaged by the second diffraction ring imaging means It is approximately equal to the ratio to the distance from the rotation center of the imaging plate. Therefore, even if the normal direction of the imaging plate and the X-ray emission direction do not match, the distance from the rotation center of the imaging plate calculated by the first correction means is the X-ray direction of the normal direction of the imaging plate. The distance from the rotation center of the imaging plate when it coincides with the emission direction of the imaging plate is accurately represented, and the residual stress of the measurement object can be measured with high accuracy. Here, the distance from the center of rotation means the distance from the actual center of rotation, and the distance from the actual center of rotation is substantially the same, but the normal direction of the imaging plate is the X-ray direction. When the direction coincides with the emission direction, it may mean the distance from the center of the diffraction ring made of a perfect circle of the reference object imaged on the imaging plate.

  In the above feature of the present invention, for example, the first diffractive ring imaging means controls the rotation means using the rotation angle detected by the rotation angle detection means, and the reference object for each of a plurality of different rotation angle positions of the imaging plate. The X-ray irradiator emits X-rays toward the, and images a plurality of diffractive rings of the reference object on the imaging plate by X-rays diffracted by the reference object. The shapes of the plurality of diffraction rings of the imaged reference object are respectively detected, and the correction means is determined from the shapes of the plurality of diffraction rings detected by the first diffraction ring shape detection means, and the positions of the plurality of diffraction rings are determined. X-ray emitted from the X-ray emitter using the fixed point axis detecting means for detecting a plurality of points or axes respectively related to X-ray emission point detection means (S118) for detecting a point at which the optical axis of the imaging plate intersects the imaging plate as an X-ray emission point, and a distance from the rotation center of the imaging plate for each predetermined angle representing the shape of the diffraction ring of the reference object Second correction means (S810) for correcting the distance from the rotation center of the imaging plate for each predetermined angle representing the shape of the diffraction ring of the measurement object and the predetermined angle using the detected X-ray emission point; And the calculation by the first correction means is performed after the correction by the second correction means.

  In this case, more specifically, the first diffractive ring imaging unit images the two diffractive rings of the reference object on the imaging plate for each rotation angle position different by 180 degrees of the imaging plate, and the fixed point axis detection unit The centroid positions of the two diffractive rings of the reference object are respectively detected from the shapes of the two diffractive rings of the detected reference object, and the X-ray emission point detecting means is an intermediate between the detected centroid positions of the two diffractive rings. A point is detected as an X-ray emission point. Further, the fixed point axis detecting means detects the positions of the centers of gravity of the plurality of diffraction rings of the reference object from the shapes of the plurality of diffraction rings of the detected reference object, respectively, and the X-ray emission point detecting means detects the detected The center position of a circle in which the centroid positions of a plurality of diffraction rings are on the circumference is detected as an X-ray emission point.

  According to this, even when the optical axis of the emitted X-ray and the rotation axis of the imaging plate do not coincide with each other, the first correction means is performed after performing correction to eliminate an error caused by the mismatch. The residual stress of the measurement object can be accurately measured.

  Furthermore, in carrying out the present invention, the present invention is not limited to the invention of the X-ray diffraction measurement device, but can also be implemented as an invention of an X-ray diffraction measurement method.

1 is an overall schematic diagram of an X-ray diffraction measurement apparatus according to an embodiment of the present invention. It is the enlarged view to which the main-body part of the X-ray-diffraction measuring apparatus of FIG. 1 was expanded. It is a flowchart which shows the reference | standard object diffraction ring measurement program performed by the controller of FIG. 11 is a flowchart illustrating in detail a first diffraction ring imaging routine of FIGS. 3 and 10. FIG. 11 is a flowchart showing in detail a first half part of a first diffraction ring reading routine of FIGS. 3 and 10. FIG. It is a flowchart which shows the latter half part of the said 1st diffraction ring reading routine in detail. 11 is a flowchart showing in detail a diffraction ring shape detection routine of FIGS. 3 and 10. 11 is a flowchart showing in detail a diffraction ring elimination routine of FIGS. 3 and 10. It is a flowchart which shows the 2nd diffraction ring imaging routine of FIG. 3 in detail. FIG. 4 is a flowchart showing in detail a first half part of a second diffraction ring reading routine of FIG. 3. FIG. It is a flowchart which shows the latter half part of the said 2nd diffraction ring reading routine in detail. It is a flowchart which shows the measurement object diffraction ring measurement program performed by the controller of FIG. It is explanatory drawing for demonstrating that a residual stress can be calculated correctly even if the attachment of an imaging plate is not favorable. It is explanatory drawing for demonstrating that the gravity center of a diffraction ring changes centering | focusing on an X-ray emission point by the rotation position of a table. It is explanatory drawing for demonstrating the method of calculating an X-ray-emitting point from the diffraction ring of several residual stress "0". It is description for demonstrating the correction | amendment by the shift | offset | difference of an X-ray emission point and the rotation center of an imaging plate. It is a figure for demonstrating the relationship between the movement distance from the movement limit position of an imaging plate, and the radial direction distance (radius) of the irradiation position of the laser beam in an imaging plate. It is explanatory drawing explaining the locus | trajectory of a reading point. It is a graph which shows an example of the light reception curve for demonstrating the peak of signal strength. It is explanatory drawing for demonstrating that the diffraction ring of residual stress "0" may not become a perfect circle depending on the attachment method of an imaging plate.

  A configuration of an X-ray diffraction measurement apparatus according to an embodiment of the present invention will be described with reference to FIGS. In order to evaluate the residual stress of the measurement object OB, this X-ray diffraction measurement apparatus irradiates the measurement object OB with X-rays and diffraction formed by diffracted X-rays from the measurement object OB due to the irradiation. Detect the shape of the ring. This X-ray diffraction measurement apparatus has a frame FR formed in a box shape, and support legs 11 are extended downward from corners of the bottom surface of the frame FR. That is, the bottom surface of the frame FR is located above the installation surface FL of the X-ray diffraction measurement apparatus. A lift 12 is provided below the frame FR. The elevator 12 has an elevator stage 12a for fixing the measurement object OB. The elevating stage 12a can be moved up and down. An opening is provided in the bottom surface of the frame FR, which is located above the elevator 12, and the fixed measurement object OB is carried into the frame FR by raising the elevating stage 12 a. Can do.

  An X-ray emitter 13 that emits X-rays, which is controlled by the X-ray control circuit 14, is fixed to the upper part of the frame FR. The direction of the exit of the X-ray emitter 13 such that the optical axis of the X-ray emitted from the X-ray emitter 13 and the normal of the measurement object OB form a predetermined angle θ (for example, 30 degrees). Is set.

  The X-ray control circuit 14 is controlled by a controller CT, which will be described later, and controls the drive current and drive voltage supplied to the X-ray emitter 13 so that X-rays with a certain intensity are emitted from the X-ray emitter 13. . In addition, the X-ray emitter 13 includes a cooling device (not shown), and the X-ray control circuit 14 also controls a drive signal supplied to the cooling device. Thereby, the temperature of the X-ray emitter 13 is kept constant.

  A moving stage 15 is provided below the X-ray emitter 13. The moving stage 15 can be moved in a direction perpendicular to the optical axis of the X-rays emitted from the X-ray emitter 13 by the stage feeder 16. The stage feeding device 16 includes a screw rod 17 that is screwed into a nut (not shown) fixed to the moving stage 15, and a feed motor 18 that rotates the screw rod 17. The screw rod 17 extends in a direction perpendicular to the optical axis of the X-ray emitted from the X-ray emitter 13. One end portion of the screw rod 17 is connected to the output shaft of the feed motor 18 fixed to the frame FR, and the other end portion is rotatably supported by the bearing portion 19 fixed to the frame FR. The moving stage 15 is sandwiched between a pair of opposing plate-like guides 20 and 20 fixed to the frame FR, and is movable along the axial direction of the screw rod 17. That is, when the feed motor 18 is driven forward or backward, the rotational motion of the feed motor 18 is converted into the linear motion of the moving stage 15. An encoder 18 a is incorporated in the feed motor 18. The encoder 18 a outputs a pulse train signal that alternately switches between a high level and a low level to the position detection circuit 21 and the feed motor control circuit 22 every time the feed motor 18 rotates by a predetermined minute rotation angle.

  The position detection circuit 21 and the feed motor control circuit 22 start to operate in response to a command from the controller CT. Immediately after the start of measurement, the feed motor control circuit 22 drives the feed motor 18 to move the moving stage 15 to the feed motor 18 side. When the pulse signal output from the encoder 18a is not input, the position detection circuit 21 outputs a signal indicating that the movement stage 15 has reached the movement limit position to the feed motor control circuit 22, and sets the count value to “0”. Set. When the feed motor control circuit 22 receives a signal indicating that the movement limit position has been reached from the position detection circuit 21, the feed motor control circuit 22 stops outputting the drive signal to the feed motor 18. The above movement limit position is set as the origin position of the moving stage 15. Therefore, the position detection circuit 21 outputs a position signal indicating “0” when the moving stage 15 moves in the upper left direction in FIGS. 1 and 2 to reach the movement limit position, and the movement stage 15 moves to the movement limit position. When moving from right to left, a signal indicating the movement distance x from the movement limit position is output as a position signal.

  When the feed motor control circuit 22 receives a set value indicating the position of the moving stage 15 from the controller CT, the feed motor control circuit 22 drives the feed motor 18 in a forward or reverse direction according to the set value. The position detection circuit 21 counts the number of pulses of the pulse signal output from the encoder 18a. Then, the position detection circuit 21 calculates the current position (movement distance x from the movement limit position) of the movement stage 15 using the counted number of pulses, and outputs it to the controller CT and the feed motor control circuit 22. The feed motor control circuit 22 drives the feed motor 18 until the current position of the moving stage 15 input from the position detection circuit 21 matches the position of the moving destination input from the controller CT.

  Further, the feed motor control circuit 22 inputs a set value indicating the moving speed of the moving stage 15 from the controller CT. Then, the moving speed of the moving stage 15 is calculated using the number of pulses per unit time of the pulse signal input from the encoder 18a, and the calculated moving speed of the moving stage 15 becomes the moving speed input from the controller CT. The feed motor 18 is driven.

  The upper ends of the pair of guides 20 are connected by a plate-like upper wall 23. A through hole 23 a is provided in the upper wall 23, and a distal end portion of the emission port of the X-ray emitter 13 is inserted into the through hole 23 a. The positions of the X-ray emitter 13 and the moving stage 15 are set so that the tip of the emission port of the X-ray emitter 13 does not contact the moving stage 15.

  A spindle motor 24 is assembled to the moving stage 15. In the spindle motor 24, an encoder 24a similar to the encoder 18a is incorporated. That is, the encoder 24 a outputs a pulse train signal that alternately switches between a high level and a low level to the spindle motor control circuit 25 and the rotation angle detection circuit 26 every time the spindle motor 24 rotates by a predetermined minute rotation angle. Furthermore, the encoder 24a outputs an index signal that switches from a low level to a high level for a predetermined short period each time the spindle motor 24 makes one rotation, to the controller CT and the rotation angle detection circuit 26.

  The spindle motor control circuit 25 and the rotation angle detection circuit 26 start to operate in response to a command from the controller CT. The spindle motor control circuit 25 inputs a set value representing the rotational speed of the spindle motor 24 from the controller CT. Then, the rotational speed of the spindle motor 24 is calculated using the number of pulses per unit time of the pulse signal input from the encoder 24a, and the drive signal is converted to the spindle so that the calculated rotational speed becomes the rotational speed input from the controller CT. Supply to the motor 24. The rotation angle detection circuit 26 counts the number of pulses of the pulse train signal output from the encoder 24a, calculates the rotation angle of the spindle motor 24, that is, the rotation angle θp of the imaging plate 28 using the count value, and sends it to the controller CT. Output. When the rotation angle detection circuit 26 receives the index signal output from the encoder 24a, the rotation angle detection circuit 26 sets the count value to “0”. That is, the position where the index signal is input is the reference position with a rotation angle of 0 degree.

  A disk-shaped table 27 is fixed to the tip of the output shaft of the spindle motor 24. The center axis of the table 27 coincides with the center axis of the output shaft of the spindle motor 24. The table 27 has a protruding portion 27a that protrudes downward from the center of the lower surface, and a thread is formed on the outer peripheral surface of the protruding portion 27a. The central axis of the protrusion 27 a coincides with the central axis of the output shaft of the spindle motor 24. An imaging plate 28 is attached to the lower surface of the table 27. The imaging plate 28 is a circular plastic film whose surface is coated with a phosphor. A through hole 28a is provided at the center of the imaging plate 28. The projection 27a is passed through the through hole 28a, and a nut-like fixture 29 is screwed into the projection 27a, whereby the imaging plate 28 is fixed. It is sandwiched between the tool 29 and the table 27 and fixed. The fixing tool 29 is a cylindrical member, and a thread corresponding to the thread of the protruding portion 27a is formed on the inner peripheral surface. The imaging plate 28 is driven by the feed motor 18 and moves together with the moving stage 15, the spindle motor 24 and the table 27 from the origin position to the diffraction ring imaging position for imaging the diffraction ring. The imaging plate 28 is driven by the spindle motor 24 to rotate and is driven by the feed motor 18 to read the imaged diffraction ring together with the moving stage 15, the spindle motor 24 and the table 27. Move within the diffractive ring erase region that erases the ring.

  Further, the moving stage 15, the output shaft of the spindle motor 24, the table 27, and the fixture 29 are provided with through holes through which the X-rays emitted from the X-ray emitter 13 pass. The center axis of these through holes and the rotation axis of the table 27 coincide. That is, when the central axis of these through holes coincides with the optical axis of the X-ray emitted from the X-ray emitter 13, the X-ray is irradiated onto the measurement object OB. Thus, the position of the imaging plate 28 when irradiating the measurement object OB with X-rays is the diffraction ring imaging position.

  A light receiving sensor 31 (for example, an X-ray CCD) including a plurality of light receiving elements that receive X-rays reflected by the measurement object OB is assembled below the feed motor 18. The light receiving sensor 31 is sufficiently separated from the measurement object OB and the imaging plate 28 toward the feed motor 18. Thus, when the imaging plate 28 is at the diffraction ring imaging position, the light receiving sensor 31 can directly receive the X-ray reflected by the measurement object OB. The light receiving surface of the light receiving sensor 31 is parallel to the upper surface of the measurement object OB. The light receiving position of the X-ray on the light receiving surface of the light receiving sensor 31 corresponds to the height of the measurement object OB. In other words, this corresponds to the distance between the imaging plate 28 and the measurement object OB. The light receiving sensor 31 outputs a light receiving signal received by each light receiving element to the sensor signal extracting circuit 32.

  The sensor signal extraction circuit 32 starts to operate in response to a command from the controller CT, calculates a peak position of the light receiving signal on the light receiving surface of the light receiving sensor 31 using the light receiving signal input from the light receiving sensor 31, and represents a light receiving position representing the light receiving position. The signal is output to the controller CT.

  A laser detection device PUH is assembled below the light receiving sensor 31. The laser detection device PUH irradiates the imaging plate 28 that images the diffraction ring with laser light, and detects the intensity of the light incident from the imaging plate 28. The laser detection device PUH is sufficiently separated from the measurement object OB and the imaging plate 28 toward the feed motor 18. That is, when the imaging plate 28 is at the diffraction ring imaging position, the X-ray diffracted by the measurement object OB is not blocked by the laser detection device PUH. The laser detection device PUH includes a laser light source 33, a collimating lens 35, a reflecting mirror 36, a polarizing beam splitter 37, a ¼ wavelength plate 38, and an objective lens 39.

  The laser light source 33 is controlled by the laser drive circuit 34 and emits laser light that irradiates the imaging plate 28. The laser drive circuit 34 is controlled by the controller CT and controls and supplies a drive signal so that laser light with a predetermined intensity is emitted from the laser light source 33. The laser drive circuit 34 receives the light reception signal output from the photodetector 51 described later, and controls the drive signal output to the laser light source 33 so that the intensity of the light reception signal becomes a predetermined intensity. Thereby, the intensity of the laser light applied to the imaging plate 28 is kept constant.

  The collimating lens 35 converts the laser light emitted from the laser light source 33 into parallel light. The reflecting mirror 36 reflects the laser light converted into parallel light by the collimating lens 35 toward the polarization beam splitter 37. The polarization beam splitter 37 transmits most (for example, 95%) of the laser light incident from the reflecting mirror 36 as it is. The quarter wave plate 38 converts the laser light incident from the polarization beam splitter 37 from linearly polarized light to circularly polarized light. The objective lens 39 focuses the laser light incident from the quarter wavelength plate 38 on the surface of the imaging plate 28.

  A focus actuator 40 is assembled to the objective lens 39. The focus actuator 40 is an actuator that moves the objective lens 39 in the optical axis direction of the laser light. The objective lens 39 is positioned at the center of the movable range when the focus actuator 40 is not energized.

  When the laser beam condensed by the objective lens 39 is irradiated onto the surface of the imaging plate 28 where the diffraction ring is imaged, a photo-stimulated luminescence phenomenon occurs. That is, after imaging the diffraction ring and irradiating the imaging plate 28 with laser light, the phosphor of the imaging plate 28 is light corresponding to the intensity of the diffracted X-ray, and light having a wavelength shorter than the wavelength of the laser light. To emit. The reflected light of the laser beam irradiated and reflected on the imaging plate 28 and the light emitted from the phosphor pass through the objective lens 39 and the quarter wavelength plate 38 and are reflected by the polarization beam splitter 37. In the reflection direction of the polarization beam splitter 37, a condenser lens 41, a cylindrical lens 42, and a photodetector 43 are provided. The condensing lens 41 condenses the light incident from the polarization beam splitter 37 on the cylindrical lens 42. The cylindrical lens 42 causes astigmatism in the transmitted light. The photodetector 43 is composed of four divided light receiving elements composed of four light receiving elements of the same square shape divided by dividing lines, and the light incident on the light receiving areas A, B, C, and D arranged in the clockwise direction. A detection signal having a magnitude proportional to the intensity is output to the amplifier circuit 44 as a light reception signal (a, b, c, d).

  The amplifying circuit 44 amplifies the received light signals (a, b, c, d) output from the photodetector 43 with the same amplification factor to generate received light signals (a ′, b ′, c ′, d ′). And output to the focus error signal generation circuit 45 and the SUM signal generation circuit 48. In this embodiment, focus servo control based on the astigmatism method is used. The focus error signal generation circuit 45 generates a focus error signal by calculation using the amplified light reception signals (a ′, b ′, c ′, d ′). That is, the focus error signal generation circuit 45 performs a calculation of (a ′ + c ′) − (b ′ + d ′), and outputs the calculation result to the focus servo circuit 46 as a focus error signal. The focus error signal (a ′ + c ′) − (b ′ + d ′) represents the amount of deviation of the focal position of the laser beam from the surface of the imaging plate 28.

  The focus servo circuit 46 is controlled by the controller CT, generates a focus servo signal based on the focus error signal, and outputs the focus servo signal to the drive circuit 47. The drive circuit 47 drives the focus actuator 40 in accordance with the focus servo signal to displace the objective lens 39 in the optical axis direction of the laser light. In this case, by generating a focus servo signal so that the value of the focus error signal (a ′ + c ′) − (b ′ + d ′) is always a constant value (for example, zero), a laser is applied to the surface of the imaging plate 28. The light can be continuously collected.

  The SUM signal generation circuit 48 adds the received light signals (a ′, b ′, c ′, d ′) to generate a SUM signal (a ′ + b ′ + c ′ + d ′) and outputs it to the A / D conversion circuit 49. To do. The intensity of the SUM signal corresponds to the intensity of the laser light reflected by the imaging plate 28 and the intensity of the light generated by the stimulated light emission, but the intensity of the laser light reflected by the imaging plate 28 is substantially constant. Therefore, the intensity of the SUM signal corresponds to the intensity of light generated by the stimulated light emission. That is, the intensity of the SUM signal corresponds to the intensity of the diffracted X-ray incident on the imaging plate 28. The A / D conversion circuit 49 is controlled by the controller CT, receives the SUM signal from the SUM signal generation circuit 48, converts the instantaneous value of the input SUM signal into digital data, and outputs the digital data to the controller CT.

  Further, the laser detection device PUH includes a condenser lens 50 and a photodetector 51. The condensing lens 50 condenses the laser light that is a part of the laser light emitted from the laser light source 33 and reflected without passing through the polarization beam splitter 37 on the light receiving surface of the photodetector 51. The photodetector 51 is a light receiving element that outputs a light reception signal corresponding to the intensity of light collected on the light receiving surface. Therefore, the photodetector 51 outputs a light reception signal corresponding to the intensity of the laser light emitted from the laser light source 33 to the laser driving circuit 34.

  Further, an LED 52 is provided adjacent to the objective lens 39. The LED 52 is controlled by the LED driving circuit 53 to emit visible light and erase the diffraction ring imaged on the imaging plate 28. The LED drive circuit 53 is controlled by the controller CT, and supplies a drive signal for generating visible light having a predetermined intensity to the LED 52.

  The controller CT is an electronic control unit mainly including a microcomputer including a CPU, ROM, RAM, a large capacity storage device, and the like, and includes the subroutines of FIGS. 4 to 9B stored in the large capacity storage device. And a measurement object diffraction ring measurement program shown in FIG. 10 are executed. The controller CT has an input device 55 for an operator to input various parameters, work instructions, and the like, and a display device 54 for visually informing the operator of various setting conditions, operating conditions, measurement results, and the like. And are connected. The controller CT processes the digital data of the SUM signal output from the A / D conversion circuit 49 to detect the intensity of the light emitted from the phosphor of the imaging plate 28.

  Hereinafter, the measurement of the shape of the diffraction ring of the measurement object OB using the X-ray diffraction measurement apparatus configured as described above will be described. In this case, because the imaging plate 28 is not properly attached to the table 27 and the normal direction of the imaging plate 28 does not exactly match the X-ray emission direction, or the imaging plate 28 is distorted. An error occurs in the shape of the diffraction ring of the measured object OB. Further, since the rotation center of the imaging plate 28 and the X-ray emission point do not exactly match, an error may be further added. In order to eliminate this error, a reference object BOB having the same material as the measurement object OB and having a residual stress of “0” is prepared, and the shape of the diffraction ring of the reference object BOB by X-ray is measured. Then, radius correction data and X-ray emission point data obtained by measuring the diffraction ring of the reference object BOB are acquired, and then the shape of the diffraction ring of the measurement object OB by X-ray is measured for detection of residual stress. At the same time, the measured value is corrected by the radius correction data and the X-ray emission point data. Before specifically describing such an operation, the radius correction data and the X-ray emission point data will be described, and the imaging plate 28 can be satisfactorily attached to the table 27 by obtaining the data. The reason why the residual stress can be calculated with high accuracy by correcting the shape of the diffraction ring of the measurement object OB will be described.

  As shown in FIG. 11A, diffraction formed on the imaging plate 28 by an object having a residual stress of “0” (hereinafter referred to as a reference object BOB) in a state where the imaging plate 28 is well attached to the table 27. The radius of the ring (reference diffraction ring) is R0, and the radius of the diffraction ring (diffractive ring of the measurement object OB) formed on the imaging plate 28 by the measurement object OB whose residual stress is measured is R1. Then, in a state where the imaging plate 28 is obliquely attached to the table 27, the radius of the diffraction ring formed on the imaging plate 28 by the reference object BOB is R0 ', and the imaging object 28 is formed on the imaging plate 28 by the measurement object OB. Let R1 'be the radius of the diffraction ring. These radii are at constant rotational positions. The diffraction ring is as shown in FIG.

  Since the deviation between the direction of the diffracted X-ray when the reference diffractive ring is imaged (one-dot chain line) and the direction of the diffracted X-ray when the diffractive ring is imaged by the measurement object OB (broken line) is very small, imaging In the vicinity where the plate 28 is irradiated with diffracted X-rays, these two directions can be considered to be parallel. Even if the imaging plate 28 is attached obliquely, if it is in a normal position near the center, the radii R0, R1, R0′R1 ′ have the relationship shown in FIG. The relationship R1 = R0 ′ / R1 ′ is established. If the distance L from the imaging plate 28 to the measurement object OB is known, the radius R0 of the reference diffraction ring is also known. Therefore, the radius R0 ′ of the reference object BOB is obtained at all rotation angles of the diffraction ring. In this case, the radius R1 of the diffraction ring of the measurement object OB on the imaging plate 28 that is well mounted can be obtained from the radius R1 ′ of the diffraction ring of the measurement object OB. If the radius R1 is obtained, the shape of the diffractive ring (normal diffractive ring of the measurement object OB) on the imaging plate 28 that is well mounted can be obtained. And if the shape of the normal diffraction ring of this measuring object OB is used, the residual stress with high accuracy of the measuring object OB can be calculated.

  In the above description, even if the imaging plate 28 is attached obliquely to the table 27, it is assumed that it is in a normal position near the center. However, when the imaging plate 28 is mounted obliquely with respect to the table 27 and is not in a normal position near the center, the relationship shown in FIG. 11 (d) is obtained, but compared with the radius R0'R1 '. The distance in the radial direction that occurs in the vicinity of the center due to the angle between the optical axis direction of the X-ray and the direction of the diffracted X-ray is very small. Good. Similarly, even if the imaging plate 28 is distorted, if the distortion seen in the radial direction at each rotation angle is a level that can be regarded as a straight line, it is considered that the relationship of R0 / R1 = R0 ′ / R1 ′ holds. Also good. Therefore, the calculation method for obtaining the radius of the normal diffraction ring of the measurement object OB can be applied to all the mountings of the imaging plate 28.

  As can be seen from the above description, in order to obtain the normal diffraction ring of the measurement object OB, the radii at the respective rotation positions of the diffraction ring by the reference object BOB and the diffraction ring by the measurement object OB may be used. The center position is necessary to obtain. This center position is a point (X-ray emission point) where the optical axis of the emitted X-ray and the imaging plate 28 intersect.

  If the rotation axis of the table 27 and the optical axis of the emitted X-ray coincide with each other, when the laser irradiation point is detected from the rotation angle and the radius in the laser irradiation from the optical head PUH, the radius “ If it is adjusted to be “0”, regardless of whether the imaging plate 28 is attached or not, the point where the optical axis of the emitted X-ray intersects the imaging plate 28 (X-ray emitting point) is always the origin. However, the rotation axis of the table 27 and the optical axis of the outgoing X-ray are often slightly shifted, and in such a case, depending on how the imaging plate 28 is attached, the optical axis of the outgoing X-ray and the imaging plate 28 Therefore, it is necessary to detect the X-ray emission point and obtain the radius and rotation angle at each rotation position of the diffraction ring with the X-ray emission point as the center. Hereinafter, a method for detecting the X-ray emission point will be described.

  When the rotational axis of the table 27 is shifted from the optical axis of the outgoing X-ray and the imaging plate 28 is not properly mounted, the imaged diffraction ring is not a perfect circle and the rotational position of the table 27 is changed. Then, as indicated by a solid line A and a broken line B in FIG. 12, the position of the imaging plate 28 changes, and the position of the diffraction ring to be imaged also changes. When the imaging plate 28 is mounted with an inclination, the diffraction ring to be imaged becomes an ellipse. The center of the ellipse (that is, the center of gravity) has a slight inclination of the optical axis of the outgoing X-ray with respect to the rotation axis of the table 27. If there is, the position changes about the X-ray emission point as in the center (center of gravity) of A and B shown in FIG. This is because, even if the diffraction ring to be imaged is not elliptical, if the deviation between the rotation axis of the table 27 and the optical axis of the outgoing X-ray is very small, changing the rotation position of the table 27 causes the diffraction ring to change. Since the position of the diffractive ring is rotated about the X-ray emission point, the position of the center of gravity of the diffraction ring changes about the X-ray emission point. That is, the X-ray emission point can be obtained by obtaining the center of a circle having the center of gravity of the diffraction ring imaged at a plurality of rotational positions of the table 27 (imaging plate 28) on the circumference.

  Specifically, as shown in FIG. 13 (a), if a diffraction ring is created at different rotation angles of 180 degrees and the respective centroids (x marks) are obtained, the X-ray emission point has two centroids (x Can be obtained as an intermediate point (black circle mark). Further, as shown in FIG. 13B, when the diffracting ring is imaged at three different rotation angles and the respective centroids are obtained, the X-ray emission point has three centroids (x marks) on the circumference. It can be obtained as the center of a circle (black circle). Of course, the diffraction ring can be imaged at four or more different rotation angles, and four or more centroids (x marks) can be obtained as the center (black circle mark) of the circle on the circumference. This center of gravity can be obtained as follows.

  The shape of the diffraction ring can be obtained as a set of data represented by the radius R0 'and the rotation angle θ. In a specific embodiment to be described later, the radius R0 ′ is used as the radius of the diffraction ring by the reference object BOB having the residual stress “0” as the radius of the diffraction ring for obtaining the center of gravity position of the diffraction ring. R0 'was adopted as the radius for matching. When the diffractive ring is represented by XY coordinates using the radius R0 'and the rotation angle θ, the shape of the diffractive ring is represented as a set of data of (R0' · cosθ, R0 '· sinθ). The X coordinate value of the centroid position is expressed as (ΣR0 ′ · cos θ) / (number of data), and the Y coordinate value of the centroid position is expressed as (ΣR0 ′ · sin θ) / (number of data).

  Then, a plurality of these gravity center positions (two in this embodiment having two different rotation angles of 180 degrees) can be obtained, and an intermediate point between them can be determined as an X-ray emission point. Specifically, the average value of the X coordinate values of the plurality of centroid positions is calculated as the X coordinate X1 of the X-ray emission point, and the average value of the Y coordinate values of the plurality of centroid positions is set as the Y coordinate Y1 of the X-ray emission point. Calculated.

  After obtaining the X-ray emission point (X1, Y1) in this way, the shape of the diffraction ring formed by the measurement object OB, that is, the rotation center of the imaging plate 28, and the diffraction ring that changes according to the rotation angle θ. The radius R1 is measured, and the measured radius R1 of the diffraction ring and the rotation angle θ at that time are measured using the X-ray emission point (X1, Y1) and the diffraction ring centered at the X-ray emission point (X1, Y1). To the radius Ra and the rotation angle θa at that time. As shown in FIG. 14, the rotation center of the imaging plate 28 when measuring the shape of the diffraction ring formed on the imaging plate 28 by the measurement object OB is O, and the rotation center O is the origin and the X-ray emission point is measured. Let the origin of the XY coordinates be Oa (X1, Y1). If the radius corresponding to the rotation angle θ of the diffraction ring of the measurement object OB is R1 ′ by measurement of the diffraction ring by the measurement object OB, the rotation center position at this time is a position represented by O. Therefore, the radius R1a ′ having the X-ray emission point as the center Oa and the rotation angle θa are expressed by the following equations 1 and 2.

そして、Ｒ０’とＲ１’のずれが微量であるので、θａとθ0aは同じ値とみなすことができる。よって、回転角度θａごとに、このように補正した半径Ｒ1a’及び半径Ｒ0a’を前記式Ｒ０／Ｒ１＝Ｒ0’／Ｒ1’のＲ1’及びＲ0’として用いれば、測定対象物ＯＢの正規回折環の半径Ｒ１を全ての回転角度において得ることができ、正規回折環の形状を得ることができる。そして、この正規回折環の形状から、ｃｏｓα法により、測定対象物ＯＢの残留応力を精度よく求めることができるようになる。次に、測定対象物ＯＢの残留応力を求めるために、上記回折環の半径Ｒ1a’，Ｒ0a’及び回転角度θａの補正演算を用いて回折環の形状を計算する具体的方法について説明する。 If the radius corresponding to the rotation angle θ of the diffraction ring of the reference object BOB is R0 ′ by measuring the diffraction ring with the reference object BOB, the rotation center position at this time is also a position represented by O. The radius R0a ′ and the rotation angle θ0a with the X-ray emission point as the center Oa are expressed as the following equations 3 and 4.

Since the difference between R0 ′ and R1 ′ is very small, θa and θ0a can be regarded as the same value. Therefore, if the radius R1a ′ and the radius R0a ′ corrected in this way are used as R1 ′ and R0 ′ in the above formula R0 / R1 = R0 ′ / R1 ′ for each rotation angle θa, the normal diffraction ring of the measurement object OB is obtained. Can be obtained at all rotation angles, and the shape of a regular diffractive ring can be obtained. Then, from the shape of the regular diffraction ring, the residual stress of the measurement object OB can be accurately obtained by the cos α method. Next, in order to obtain the residual stress of the measurement object OB, a specific method for calculating the shape of the diffraction ring using the correction operations of the radii R1a ′ and R0a ′ and the rotation angle θa of the diffraction ring will be described.

  First, an operator attaches a reference object BOB (an object having a residual stress of “0”) to the elevating stage 12a of the elevator 12, raises the elevating stage 12a, and sets the reference object BOB in the frame FR. In this case, the reference object BOB having a residual stress “0” is an iron material having a residual stress “0” obtained by applying iron powder to the object. An operator inputs the material (for example, iron) of the reference object BOB using the input device 55 and instructs the measurement start of the reference diffraction ring. Thereby, the controller CT starts the execution of the reference object diffraction ring measurement program shown in FIG. 3 in step S100.

  After starting the execution of the reference object diffraction ring measurement program, the controller CT executes a first diffraction ring imaging routine in step S102. This first diffractive ring imaging routine is started in step S200 of FIG. 4, and in step S202, the controller CT rotates the imaging plate 28 at a low speed with respect to the spindle motor control circuit 25, and outputs an index signal from the encoder 24a. At the time of input, the rotation of the imaging plate 28 is stopped. Thereby, at the start of measurement, the rotation angle of the imaging plate 28 is set to 0 degree. Next, in step S <b> 204, the controller CT controls the feed motor control circuit 22 and the position detection circuit 21 to operate the feed motor 18 and diffract the imaging plate 28 in cooperation with the position detection circuit 21. Move to the ring imaging position.

  Next, the controller CT starts the operation of the sensor signal extraction circuit 32 in step S206. Next, in step S208, the controller CT controls the X-ray control circuit 14 to cause the X-ray emitter 13 to start emitting X-rays. Thereby, X-rays are irradiated onto the measurement object OB, and the X-rays reflected on the surface of the measurement object OB are received by the light receiving sensor 31. Next, in step S210, the controller CT inputs a light reception position signal from the sensor signal extraction circuit 32, and calculates a distance L between the imaging plate 28 and the measurement object OB using the input light reception position signal. Note that the calculated distance L is stored in a memory because it is used by processing to be described later. In step S212, the controller CT determines whether or not the calculated distance L is within a predetermined reference range. If the distance L is not within the reference range, it is determined as “No”, and in step S214, the X-ray control circuit 14 is controlled to stop the X-ray irradiation to the measurement object OB.

  In step S216, the controller CT displays on the display device 54 that the position of the measurement object OB in the height direction is inappropriate, and information on the height adjustment of the lifting stage 12a of the elevator 12. indicate. That is, it displays how much the lifting stage 12a should be raised or lowered. In step S226, which will be described later, the execution of the first diffraction ring imaging routine is terminated. In this case, the operator instructs the start of measurement again using the input device 55 after adjusting the height of the lifting stage 12a. Since the time required from the above steps S208 to S214 is very short, the diffractive ring is not imaged on the imaging plate 28. Further, when the light receiving sensor 31 does not receive the X-ray reflected by the measurement object OB, only an indication that the position of the measurement object OB in the height direction is inappropriate is made in step S216. Thus, information relating to the height adjustment of the elevating stage 12a is not displayed. In this case, the position of the measurement object OB is considered to be in an extremely inappropriate position, and the height adjustment direction of the elevating stage 12a can be visually determined. In response to the measurement start instruction, the processes in steps S202 to S212 described above are performed again, and the processes are repeated until the distance L is within a predetermined reference range. However, the processes in steps S202 to S206 are substantially unnecessary.

  On the other hand, if the distance L is within the predetermined reference range during the determination process in step S212, the controller CT determines “Yes” in step S212, proceeds to step S218, and outputs a sensor signal extraction circuit. The operation of 32 is stopped. Then, the controller CT starts time measurement in step S220, and determines whether or not a predetermined set time has elapsed in step S222. If the predetermined set time has not elapsed since the start of time measurement, it is determined as “No” in step S222 and the determination process is continued. That is, the controller CT stands by until a predetermined set time elapses from the start of time measurement. When a predetermined set time elapses from the start of time measurement, the controller CT determines “Yes” in step S222, and controls the X-ray control circuit 14 in step S224 to control the X-ray emitted by the X-ray emitter 13. The irradiation of the line is stopped, and the execution of the first diffraction ring imaging routine is terminated in step S226.

  As a result, the diffraction ring formed by the reference object BOB having the residual stress “0” is imaged on the imaging plate 28.

  After execution of the first diffraction ring imaging routine, the controller CT starts execution of the first diffraction ring reading routine of FIGS. 5A and 5B in step S104 of FIG. In this case, the controller CT also starts executing the diffraction ring shape detection routine of FIG. 6 in parallel with the execution of the first diffraction ring reading routine. The execution of the first diffraction ring reading routine is started in step S300 of FIG. 5A, and the controller CT calculates the diffraction ring reference radius R0 in step S302. The diffraction ring reference radius R0 is the radius of the diffraction ring when the residual stress of the measurement object OB is “0”, that is, the reference radius of the diffraction ring of the reference object BOB. The diffraction ring reference radius R0 depends on the material of the measurement object OB and the distance L from the imaging plate 28 to the measurement object OB. That is, since the residual stress is “0”, the diffraction angle θx is determined by the material (in this embodiment, iron). Since the distance L and the diffraction ring reference radius R0 are in a proportional relationship, if the diffraction angle θx is stored in advance for each material, the diffraction ring reference radius R0 is calculated by the calculation of R0 = L · tan (θx). it can. The calculated diffraction ring reference radius R0 is stored in the memory.

  After the processing in step S302, the controller CT starts the operation of the position detection circuit 21 in step S304. In step S306, the feed motor control circuit 22 is instructed to move the imaging plate 28 to the reading start position in the diffraction ring reading region. The feed motor control circuit 22 drives and controls the feed motor 18 in cooperation with the position detection circuit 21 to move the imaging plate 28 to the reading start position. In a state where the imaging plate 28 is at the reading start position, the center of the objective lens 39, that is, the irradiation position of the laser beam is located at a position smaller than the calculated diffraction ring reference radius R0 by a predetermined distance α. The predetermined distance α is a distance that is slightly larger than the distance at which the radius of the imaged diffraction ring may deviate from the diffraction ring reference radius R0. Thereby, the measurement of the diffraction ring is sufficiently started from the inside by the processing described later, and the diffraction ring is reliably detected.

  Here, the position signal from the position detection circuit 21 indicating the movement distance x from the movement limit position of the moving stage 15 to the lower right direction in FIGS. The relationship with the distance (ie, the radius r of the irradiation position of the laser beam) to the center position of the lens 39 will be described. In the state where the moving stage 15, that is, the imaging plate 28 is at the movement limit position, as shown in FIG. 15A, the distance from the center of the imaging plate 28 to the center position of the objective lens 39 is Rx. In this case, the objective lens 39 is in the upper left direction in FIGS. 1 and 2 from the center position of the imaging plate 28, and the distance Rx is measured in advance and stored in the controller CT. On the other hand, as shown in FIG. 15B, when the imaging plate 28 is moved from the movement limit position by the distance x in the lower right direction in FIGS. It is represented by In this case, since the distance x is indicated by the position signal output from the position detection circuit 21 as described above, the radius r of the irradiation position of the laser beam is the position output from the position detection circuit 21 in future processing. The value Rx stored in advance is added to the distance x represented by the signal.

  As described above, when the imaging plate 28 is moved to the reading start position, as shown in FIG. 15 (c), the irradiation position of the laser beam is inside the diffraction ring reference radius R0 by a predetermined distance α. Therefore, the radius r in this case should be equal to the distance R0-α. Therefore, the distance x for moving the imaging plate 28 from the drive limit position in the lower right direction in FIGS. 1 and 2 is equal to x = R0−α−Rx. That is, in the movement process to the reading start position in the step S306, the table 27 is set to the distance x (= R0−α−Rx) represented by the position signal output from the position detection circuit 21 as shown in FIGS. What is necessary is just to move to the lower right direction.

  Next, in step S308, the controller CT instructs the spindle motor control circuit 25 to rotate the imaging plate 28 at a predetermined constant rotational speed. The spindle motor control circuit 25 controls the rotation of the spindle motor 24 so that the imaging plate 28 rotates at the specified constant rotation speed while calculating the rotation speed using the pulse signal from the encoder 24a. Accordingly, the imaging plate 28 starts to rotate at the predetermined constant rotational speed. Next, in step S310, the controller CT controls the laser drive circuit 34 to start irradiation of the imaging plate 28 with laser light from the laser light source 33.

  Next, in step S312, the controller CT instructs the focus servo circuit 46 to start focus servo control. Accordingly, the focus servo circuit 46 starts focus servo control by driving and controlling the focus actuator 40 via the drive circuit 47 using the focus error signal from the amplifier circuit 44 and the focus error signal generation circuit 45. . As a result, the objective lens 39 is driven and controlled in the optical axis direction so that the laser beam is focused on the surface of the imaging plate 28. After the process of step S312, the controller CT starts the operation of the rotation angle detection circuit 26 and the A / D conversion circuit 49 in step S314. As a result, the rotation angle detection circuit 26 starts outputting the rotation angle θp from the reference position of the spindle motor 24 (imaging plate 28) to the controller CT, and the A / D conversion circuit 49 outputs the digital data of the instantaneous value of the SUM signal. Starts to be output to the controller CT.

  Next, in step S316, the controller CT instructs the feed motor control circuit 22 to start and move the imaging plate 28. The feed motor control circuit 22 drives and controls the feed motor 18 to move the imaging plate 28 from the reading start position to the bearing portion 19 side (lower right direction in FIGS. 1 and 2) at a constant speed. Thereby, the irradiation position of the laser beam starts to move relative to the imaging plate 28 at a constant speed from the inside to the outside by a predetermined distance α from the diffraction ring reference radius R0. In this state, the irradiation position of the laser beam is relatively spirally rotated on the imaging plate 28 by the processing in steps S308 and S316.

  After the processing in step S316, the controller CT initially sets the values of the circumferential direction number n and the radial direction number m to “1” in step S318. The circumferential direction number n is an integer that changes from “1” representing the circumferential position obtained by equally dividing one rotation of the imaging plate 28 into N pieces (a predetermined large value) to the maximum value N. The radial direction number m represents a radial position from the inside to the outside of the imaging plate 28, and is a value that increases by “1” from “1” each time the imaging plate 28 rotates once. These circumferential direction number n and radial direction number m indicate a reading point P (n, m) that moves spirally on the imaging plate 28 as shown in FIG.

  Next, in step S320, the controller CT determines whether or not the rotation angle detection circuit 26 has input an index signal from the encoder 24a. If the rotation angle detection circuit 26 has not input the index signal, the controller CT determines “No” in step S320 and continues to execute the determination process in step S320 repeatedly. When the rotation angle detection circuit 26 inputs the index signal, the controller CT determines “Yes” in step S320, and captures the current rotation angle θp of the imaging plate 28 from the rotation angle detection circuit 26 in step S322. . In step S324, the controller CT calculates the difference between the current rotation angle θp and the rotation angle (n−1) · θo specified by the variable n (in this case, n = 1 and “0”). It is determined whether or not the absolute value | θp− (n−1) · θo | is less than a predetermined allowable value. In this case, θo is a predetermined value stored in advance by dividing 360 degrees by the maximum value N of the circumferential direction number n. If the absolute value | θp− (n−1) · θo | is not less than the predetermined allowable value, the controller CT determines “No” in step S324 and repeatedly executes the processes in steps S322 and S324. That is, the controller CT stands by until the current rotation angle θp substantially matches the predetermined rotation angle (n−1) · θo. When the current rotation angle θp substantially coincides with the predetermined rotation angle (n−1) · θo, the controller CT determines “Yes” in step S324, that is, the absolute value | θp− (n−1) · θo | Is less than the predetermined allowable value, the process proceeds to step S326.

  In step S326, the controller CT takes the SUM signal from the A / D conversion circuit 49 and stores it in the memory as the signal intensity S (n, m) of the reading point P (n, m). In step S326, the position signal from the position detection circuit 21 is acquired, the radius r is calculated by adding the predetermined distance Rx to the distance x represented by the position signal, and the reading point P (n, m ) Radius r (n, m) and stored in the memory in correspondence with the signal intensity S (n, m). Thereby, the signal intensity S (n, m) representing the intensity of the photostimulated luminescence from the reading point P (n, m) of the imaging plate 28, that is, the intensity of the X-ray diffracted light with respect to the reading point P (n, m), It is stored in memory with a radius r (n, m) representing the radius of the read point P (n, m).

  Next, in step S328, the controller CT determines whether or not the stored signal strength S (n, m) is greater than or equal to a predetermined reference value. If the signal strength S (n, m) is greater than or equal to the predetermined reference value, the controller CT determines “Yes” in step S328 and proceeds to step S332. On the other hand, if the signal strength S (n, m) is smaller than the predetermined reference value, the controller CT determines “No” in step S328, and in step S330, the stored signal strength S (n, m). After erasing m) and radius r (n, m), the process proceeds to step S332. The signal intensity S (n, m) and the radius r (n, m) are erased when the signal intensity S (n, m) smaller than a predetermined reference value is detected as the peak position of the diffraction X-ray intensity in the radial direction of the diffraction ring. This is because it is unnecessary.

  In step S332, the controller CT adds “1” to the circumferential direction number n. In step S334, the controller CT determines whether the variable n is greater than a value N representing the number of reading points P (n, m) per revolution, that is, whether the imaging plate 28 has made one revolution. . In this case, since n = 2 and the circumferential direction number n is equal to or less than the value N, the controller CT determines “No” in step S334 and returns to step S322.

  Then, the processes of steps S322 to S334 described above are repeated until the circumferential direction number n becomes larger than the value N. By repeating these steps S322 to S334, the signal intensity S (n, m) and radius r () for each predetermined angle θo corresponding to the rotation angles 0, θo, 2 · θo (N−1) · θo, respectively. n, m) is stored in the memory. However, also in this case, if the signal strength S (n, m) is smaller than a predetermined reference value by the processing of steps S328 and S330, the signal strength S (n, m) and the radius r (n, m) stored in the memory are stored. m) is erased.

  When the circumferential direction number n becomes larger than the value N by the circulation processing in steps S322 to S334, the controller CT determines “Yes” in step S334, and in step S336, the diffractive ring shape described later. The presence / absence of an end command by the detection routine is determined. If there is no termination command yet, the controller CT determines “No” in step S336, adds “1” to the radial direction number m in step S338 (in this case, m = 2), and step In S340, the circumferential direction number n is returned to "1". Then, the controller CT executes the processing of steps S320 to S340 described above, and the reading point P corresponding to the rotation angle 0, θo, 2 · θo (N−1) · θo of the next radial position. The signal strength S (n, m) and radius r (n, m) for (n, m) are stored in the memory. Then, until the end command is given, by the processing of steps S320 to S340, the radial direction number m (= 1, 2, 3,...) That sequentially increases by “1” and each radial direction number m Corresponding to a reading point P (n, m) designated by a circumferential direction number n (= 1 to N) corresponding to θ0, θo, 2 · θo (N−1) and θo, respectively. The signal strength S (n, m) and the radius r (n, m) are sequentially stored in the memory. Also in this case, if the signal strength S (n, m) is smaller than a predetermined reference value, the signal strength S (n, m) and the radius r (n, m) stored in the memory are deleted.

  When there is an instruction to end the diffraction ring shape detection routine, the controller CT determines “Yes” in step S336, and proceeds to step S342 in FIG. 5B. Here, a diffraction ring shape detection routine executed in parallel with the first diffraction ring reading routine will be described.

  The execution of the diffraction ring shape detection routine is started in step S400 of FIG. 6, and the controller CT initializes the circumferential direction number n to “1” in step S402. The circumferential direction number n indicates the circumferential position for each predetermined angle θo as in the case of the first diffraction ring reading routine, but the circumferential direction number n used in the first diffraction ring reading routine. It is independent.

  After the process of step S402, the controller CT determines in step S404 whether a peak radius rp (n) described later in detail exists, that is, whether the peak radius rp (n) has been detected. In this case, at the peak radius rp (n), the rotation angle of the detected peak radius is represented by the variable n. If the peak radius rp (n) has been detected, the controller CT determines “Yes” in step S404, adds “1” to the circumferential direction number n in step S406, and in step S408, It is determined whether or not the direction number n is greater than a predetermined number. The predetermined number in this case is also a value N representing the number of measurement positions in one round. If the circumferential direction number n is less than or equal to the predetermined number, the controller CT determines “No” in step S408 and returns to step S404. If the circumferential direction number n is larger than the predetermined number, the controller CT determines “Yes” in step S408, and returns to step S402 to return the circumferential direction number n to “1”.

  On the other hand, if the peak radius rp (n) is not detected, the controller CT determines “No” in step S404, and stores the signal intensity S (() stored in step S410 in step S326 in FIG. 5A. It is determined whether the number of (n, m) is greater than or equal to a predetermined number. If the number of signal strengths S (n, m) is not equal to or greater than the predetermined number, the controller CT determines “No” in step S410, executes the processes of steps S406 and S408 described above, and executes step S404 or step S404. Return to S402. This is because the determination processing in step S410 is useless even if the peak detection processing described later is executed when the number of signal strengths S (n, m) is small. Note that the signal strength S (n, m) erased by the process of step S330 in FIG. 5A is not counted as the stored signal strength S (n, m).

  On the other hand, when the number of the stored signal intensities S (n, m) is equal to or larger than the predetermined number, the controller CT determines “Yes” in step S410 and determines the presence or absence of a peak in step S412. To do. That is, the presence / absence of a peak in the value of the SUM signal is determined using all the radii r (n, m) and the signal strength S (n, m) at the circumferential position designated by the circumferential number n. Specifically, as shown in FIG. 17, all the radii r (n, m) at the circumferential position designated by the circumferential number n are taken on the horizontal axis and corresponded to the radius r (n, m). Whether the signal intensity S (n, m) has a peak in the light receiving curve with the signal intensity S (n, m) on the vertical axis, that is, has the signal intensity S (n, m) decreased after increasing? It is good to judge. If the peak does not exist, the controller CT determines “No” in step S412, executes the processes of steps S406 and S408 described above, and returns to step S404 or step S402.

  As described above, while the steps S402 to S412 are repeatedly executed, the radius r (n, m) and the signal strength S (n, m) are further increased by the processing of the first diffraction ring reading routine executed in parallel. ) Is captured and stored in memory one after another. For this reason, the peak is detected in step S412, and when detected, the controller CT determines “Yes” in step S412 and in step S414, the peak radius r (n, m ) As a peak radius rp (n). Next, in step S416, the controller CT determines whether or not the number of acquired peak radii rp (n) is a predetermined number or more. The predetermined number in this case is also a value N representing the number of measurement positions in one round. If the number of acquired peak radii rp (n) is smaller than the predetermined number, the controller CT determines “No” in step S416, and executes the processes of steps S406 and S408 described above to execute step S404 or step S404. Return to S402.

  By repeating the processing of steps S402 to S416 in this way, the number of acquired peak radii rp (n) increases and reaches a predetermined number, that is, at all reading points P (n, m) in the circumferential direction. When the peak radius rp (n) is acquired, the controller CT determines “Yes” in step S416, and outputs an end command indicating the end of diffraction ring shape detection in step S418. Then, the controller CT ends the execution of the diffraction ring shape detection routine in step S420.

  Here, the description returns to the description of the first diffraction ring reading routine of FIGS. 5A and 5B. When the end command is output as described above, the controller CT determines “Yes” in step S336 in FIG. 5A, and stops the focus servo control for the focus servo circuit 46 in step S342 in FIG. 5B. To stop the focus servo control. Next, in step S344, the controller CT controls the laser driving circuit 34 to stop the laser light irradiation by the laser light source 33. Further, the controller CT stops the operations of the A / D conversion circuit 49 and the rotation angle detection circuit 26 in step S346, and controls the feed motor control circuit 22 to stop the operation of the feed motor 18 in step S348. As a result, the imaging plate 28 is stopped, and the execution of the diffraction ring shape detection routine is terminated in step S350. Note that the operation of the position detection circuit 21 and the rotation of the imaging plate 28 are continued as before.

  In the future processing, the radius R0 calculated and stored by the processing in step S302 of the first diffraction ring reading routine in FIG. 5A is the reference object BOB which is the residual stress “0” that is well attached to the table 27. Is treated as data representing the radius R0 of the diffraction ring. Further, the circumferential direction number n (1 to N), that is, the rotation angles 0, θo, 2 · θo (N−1) · θo detected and stored by the processing of step S414 of the diffraction ring shape detection routine of FIG. The peak radius rp (n) (1 to N) of the diffraction ring for each rotation angle of the corresponding reference object BOB is the reference object having the residual stress “0” attached to the table 27 with the imaging plate 28 in a poor state. It is treated as data for each rotation angle θo representing the shape of the diffraction ring by BOB, that is, radius R0 ′. Therefore, in the future processing, the peak radius rp (n) (1 to N) is set to the radius R0 ′ (of the diffraction ring by the reference object BOB having the residual stress “0” attached to the table 27 in an unfavorable state. 1), R0 ′ (2)... R0 ′ (N).

  Returning to the description of FIG. 3 again, the controller CT, after the process of step S104, determines the gravity center position of the diffraction ring for each rotation angle of the reference object BOB attached to the table 27 in an unfavorable state in step S106. Calculate As described above, the X coordinate value of the centroid position is expressed as (ΣR0 ′ · cos θ) / (number of data), and the Y coordinate value of the centroid position is expressed as (ΣR0 ′ · sin θ) / (number of data). The R0 ′ corresponds to the radii R0 ′ (1), R0 ′ (2)... R0 ′ (N) of the diffraction rings stored in the memory, and the θ is the rotation angle 0, θo, 2 · θo (N-1) · Since it corresponds to θo, these radii R0 '(1), R0' (2) ... R0 '(N) and rotation angles 0, θo, 2 · θo (N-1)-The X and Y coordinate values of the center of gravity can be calculated by the following formulas 5 and 6 using θo.

  After the process of step S106, the controller CT executes the diffraction ring elimination routine of FIG. 7 in step S108. The execution of the diffractive ring erasing routine is started in step S500, and the controller CT instructs the feed motor control circuit 22 to move the imaging plate 28 to the erasing start position in the diffractive ring erasing region in step S502. To do. The feed motor control circuit 22 drives and controls the feed motor 18 in cooperation with the position detection circuit 21 to move the imaging plate 28 to the erase start position. When the imaging plate 28 is at the erasing start position, the center of the visible light output from the LED 52 is located at a position smaller than the calculated diffraction ring reference radius R0 by a predetermined distance γ. Specifically, this position is output from the position detection circuit 21 when the distance from the center of the imaging plate 28 to the center of the visible light of the LED is Ry ′ in a state where the imaging plate 28 is at the drive limit position. This is the position where the position becomes R0-γ-Ry ′. Note that the predetermined distance γ is slightly larger than the predetermined distance α and is a position shifted with a margin from the radius of the imaged diffraction ring. Thereby, the imaged diffraction ring is surely erased by a process described later.

  Next, in step S504, the controller CT controls the LED drive circuit 53 to start irradiation of the visible light to the imaging plate 28 by the LED 52. Next, in step S506, the controller CT instructs the feed motor control circuit 22 to start and move the imaging plate 28. The feed motor control circuit 22 drives and controls the feed motor 18 to move the imaging plate 28 from the erase start position to the bearing portion 19 side (lower right direction in FIGS. 1 and 2) at a constant speed. As a result, the visible light from the LED 52 starts moving at a constant speed from the inside to the outside by a predetermined distance γ (γ> α) from the diffraction ring reference radius R0 while rotating in the imaging plate 28.

  After the processing in step S506, the controller CT inputs a position signal indicating the position of the imaging plate 28 from the position detection circuit 21 in step S508. In step S510, the current position of the imaging plate 28 indicates the erasure end position. Determine if it has exceeded. This end position is a position larger than the diffraction ring reference radius R0 by a predetermined distance γ. Specifically, the position output from the position detection circuit 21 is a position where R0 + γ−Ry ′. Then, until the current position of the imaging plate 28 exceeds the erasing end position, the controller CT determines “No” in step S510, and repeatedly executes the processes of steps S508 and S510. Thereby, visible light from the LED 52 is irradiated from the diffraction ring reference radius R0 to the rotating imaging plate 28 from the inner side by a predetermined distance γ to the outer side by a predetermined distance γ, so that the diffraction formed by the diffracted X-rays. The ring is gradually erased from the inside.

  When the current position of the imaging plate 28 exceeds the erasing end position, the controller CT determines “Yes” in step S510, and causes the feed motor control circuit 22 to stop moving the imaging plate 28 in step S512. In step S514, the LED driving circuit 53 is instructed to stop the irradiation of visible light by the LED 52. Accordingly, the feed motor control circuit 22 stops the movement of the imaging plate 28 by stopping the operation of the feed motor 18. The LED drive circuit 53 stops the irradiation of visible light from the LED 52. In this state, the imaged diffraction ring is completely erased.

  After the processing in step S514, the controller CT stops the operation of the position detection circuit 21 in step S516, and instructs the spindle motor control circuit 25 to stop the rotation of the imaging plate 28 in step S518. In response to this instruction, the spindle motor control circuit 25 stops the operation of the spindle motor 24 and stops the rotation of the imaging plate 28. After the rotation of the imaging plate 28 is stopped, the controller CT ends the execution of the diffraction ring elimination routine in step S520.

  Returning to the description of FIG. 3, the controller CT executes the second diffractive ring imaging routine of FIG. 8 in step S110 after the process of step S108. This second diffractive ring imaging routine is started in step S600 of FIG. 8, and the controller CT activates the rotation angle detection circuit 26 and activates the spindle motor control circuit 25 in step S602 to operate the imaging plate 28. When the rotation speed is low and the rotation angle θp detected by the rotation angle detection circuit 26 reaches 180 degrees, the spindle motor control circuit 25 is controlled to stop the rotation of the imaging plate 28. As a result, the imaging plate 28 is set to a rotation angle shifted by 180 degrees from that during imaging of the first diffraction ring. Next, in step S604, the controller CT operates the feed motor 18 to move the imaging plate 28 to the diffraction ring imaging position in the same manner as in step S204 of the first diffraction ring imaging routine of FIG. 4 described above. .

  Next, the controller CT irradiates the measurement object OB with X-rays for a predetermined set time by the processing of steps S606 to S612 similar to steps S208 and S220 to S224 of the first diffraction ring imaging routine of FIG. In step S614, the execution of the second diffractive ring imaging routine is terminated. In this case, since the height adjustment of the elevating stage 12a is completed by executing the first diffraction ring imaging routine, step S206 for adjusting the height of the elevating stage 12a in the first diffraction ring imaging routine of FIG. , S210 to S218 are omitted. Thereby, in the state where the imaging plate 28 is rotated by 180 degrees from the case of the first diffraction ring reading routine, the imaging plate 28 images the reference diffraction ring of the reference object BOB having the residual stress “0”.

  After the execution of the second diffraction ring imaging routine, the controller CT starts execution of the second diffraction ring reading routine of FIGS. 9A and 9B in step S112 of FIG. In this case, the controller CT also starts the execution of the diffraction ring shape detection routine of FIG. 6 in parallel with the execution of the second diffraction ring reading routine. The second diffraction ring reading routine includes steps S700 to S750, and steps S700 to S720 and steps S724 to S750 are the same as the processes of steps S300, S304 to S322, and S324 to S350 of the first diffraction ring reading routine of FIG. 5A. is there. The only difference is that the calculation process of the diffraction ring reference radius R0 in step S302 in FIG. 5A is omitted, and the process of shifting the rotation angle θp in step S722 in FIG. 9A by 180 degrees is added. In the specific process of step S722, if the rotation angle θp detected by the process of step S720 is in the range of 0 to 180 degrees, 180 degrees is added to the rotation angle θp, and the process is detected by the process of step S720. If the rotation angle θp is within the range of 180 to 360 degrees, 180 degrees is subtracted from the rotation angle θp. The former difference is because there is no need to calculate the diffractive ring reference radius R0 redundantly. The latter difference is that in the second diffraction ring imaging routine in step S110, the imaging plate 28 is rotated 180 degrees to image the diffraction ring compared to the first diffraction ring imaging routine in step S102. This is because detection is performed with the same coordinate axes as in the first diffraction ring reading routine in the state when the imaged diffraction ring is imaged (see FIGS. 12 and 13).

  By executing the second diffraction ring reading routine and the diffraction ring shape detection routine, the circumferential direction number n (1 to N), that is, the rotation angle 0, .theta.o, 2.multidot..theta.o (N-1) .multidot.peak radius rp (n) (1 to N) of the diffraction ring for each rotation angle of the reference object BOB corresponding to .theta.o is detected and stored. The peak radius rp (n) (1 to N) is equal to the radius R0 ′ (1) of the diffraction ring formed by the reference object BOB having a residual stress “0” in a state where the imaging plate 28 is obliquely attached to the table 27 , R0 ′ (2)... R0 ′ (N) and the radius R0 ′ (1) of the diffraction ring in a state where the imaging plate 28 is rotated by 180 degrees compared to the case of the first diffraction ring reading routine. ), R0 ′ (2)... R0 ′ (N).

  Returning to the description of FIG. 3 again, after the processing of step S112, the controller CT rotates the imaging plate 28 attached to the table 27 in an unfavorable state by 180 degrees in step S114. The barycentric position of the diffraction ring formed on the imaging plate 28 for each rotation angle of the reference object BOB which is “0” is calculated. As described above, in this case, the X coordinate value of the centroid position is expressed as (ΣR0 ′ · cos θ) / (number of data), and the Y coordinate value of the centroid position is (ΣR0 ′ · sin θ) / (number of data). In this case, the X and Y coordinates of the center of gravity position are the radius R0 ′ (1) for each rotation angle obtained by the processing of the second diffraction ring reading routine and the diffraction ring shape detection routine in step S112. , R0 ′ (2)... R0 ′ (N) are calculated by the arithmetic expressions of the above formulas 5 and 6.

  After the process of step S114, the controller CT executes the diffraction ring elimination routine of FIG. 7 in step S116. By executing this diffraction ring elimination routine, the diffraction rings imaged on the imaging plate 28 by the execution of the second diffraction ring imaging routine in step S110 are erased in the same manner as described above.

  After the process of step S116, the controller CT uses the centroid position of the diffraction ring calculated in step S106 and the centroid position calculated in step S114 in step S118, and the X-ray emission points X1, Y1. Calculate The calculation of the X-ray emission points X1 and Y1 is as described above, and the intermediate position between the two calculated center positions is calculated as the X-ray emission points X1 and Y1. Specifically, the median value (that is, the average value) of the two X coordinate values of the barycentric position calculated by the calculation of Equation 3 in steps S106 and S114 is calculated as the X coordinate value X1 of the X-ray emission point, In Steps S106 and S114, the median value (that is, the average value) of the two Y coordinate values of the center of gravity calculated by the calculation of Equation 4 is calculated as the X coordinate value X1 of the X-ray emission point. After the process of step S118, the controller CT ends the execution of the reference object diffraction ring measurement program in step S120.

  Next, the operator attaches the measurement object OB whose residual stress is to be measured to the elevation stage 12a of the elevator 12, raises the elevation stage 12a, and sets the measurement object OB in the frame FR. Then, the operator uses the input device 55 to instruct the start of measurement of the diffraction ring of the measurement object OB. Thereby, controller CT starts execution of the measuring object diffraction ring measurement program shown in FIG. 10 in step S800.

  After the execution of the measurement object diffraction ring measurement program, the controller CT executes the first diffraction ring imaging routine of FIG. 4 described above in step S802. By executing the first diffractive ring imaging routine, the diffractive ring is imaged on the imaging plate 28 in a state where the imaging plate 28 is at the reference rotation position, that is, at a rotation angle of 0 degree. Next, in step S804, the controller CT starts execution of the first diffraction ring reading routine of FIGS. 5A and 5B described above. Also in this case, the controller CT starts the execution of the diffraction ring shape detection routine of FIG. 6 in parallel with the execution of the first diffraction ring reading routine. By executing this first diffraction ring reading routine, the rotation angle of the measurement object OB corresponding to the circumferential direction number n (1 to N), that is, the rotation angles 0, θo, 2 · θo (N−1) · θo. The peak radius rp (n) (1 to N) of each diffraction ring is detected and stored. In the future processing, the measurement object OB corresponding to the detected and stored circumferential direction number n (1 to N), that is, the rotation angles 0, θo, 2 · θo (N−1) · θo The peak radius rp (n) (1 to N) of the diffractive ring for each rotation angle is a rotation representing the shape of the diffractive ring, that is, the radius R1 ′ by the measurement object OB attached to the table 27 in a state where the imaging plate 28 is not good. It is treated as data for each angle θo. Accordingly, in future processing, the peak radii rp (n) (1 to N) are set to the radii of the diffraction rings R1 ′ (1) and R1 ′ (2) by the measuring object OB attached to the table 27 in an unfavorable state. ) ... R1 '(N). In this case, the calculation of the diffraction ring reference radius R0 in step S302 of FIG. 5A is executed, but this calculation is executed in step S302 of FIG. 5A when the residual stress is “0”. Actually, this processing is unnecessary.

  After the processing of step S804, the controller CT executes the diffraction ring elimination routine of FIG. 7 in step S806. By executing this diffractive ring erasing routine, the diffractive ring relating to the measurement object OB imaged on the imaging plate 28 by executing the first diffractive ring imaging routine in step S802 is erased in the same manner as described above.

  After the process of step S806, the controller CT corrects the measurement error of the radius of the diffraction ring because the rotation center of the imaging plate 28 and the X-ray emission point do not exactly coincide with each other in step S808. The rotation angle corresponding to the measurement radius is corrected. That is, the radius R1 ′ (n) (n = 1 to N) of the diffraction ring by the measurement object OB and the rotation angle θ (n) (= (n−1) · θo) (n = 1 to N) corresponding to them. ) Is corrected by using the XY coordinate values X1 and Y1 of the X-ray emission point calculated by the process of step S118 in FIG. 3, so that the radius R1a ′ of each point of the diffraction ring with the X-ray emission point as the origin is corrected. (n) (n = 1 to N) and the corresponding rotation angle θa (n) (n = 1 to N) are calculated. Then, the radius R0 ′ (n) (n = 1 to N) of the diffraction ring formed by the reference object BOB is similarly corrected using the XY coordinate values X1 and Y1 of the X-ray emission point, so that the X-ray emission point is set to the origin. The radius R0a '(n) (n = 1 to N) of each point of the diffraction ring is calculated. In this case, R1 ′ (n), θ (n), R0 ′, X1, Y1, R1a ′ (n), R0a ′ (n), and θa (n) are in the relationship of the above-described equations 1-3. , The radius R1a '(n) (n = 1 to N) of the diffractive ring of the measurement object OB, the corresponding rotation angle θa (n) (n = 1 to N) and the radius R0a' of the diffractive ring of the reference object BOB (n) (n = 1 to N) is calculated by the following formulas 7 to 9.

  After the processing of step S808, the controller CT corrects the measurement error of the radius of the diffraction ring that occurs because the normal direction of the imaging plate 28 does not exactly match the X-ray emission direction in step S810. That is, the correction value R1a ′ (n) (n = 1 to N) of the diffraction ring radius by the measurement object OB calculated in step S808 and the correction value R0a ′ (n of the diffraction ring radius by the reference object BOB). n) Using the diffraction ring reference radius R 0 (n = 1 to N) and the diffraction ring reference radius R 0, the diffraction ring by the measurement object OB (that is, by the measurement object OB) in a state where the imaging plate 28 is satisfactorily attached to the table 27. The radius R1 (n) (n = 1 to N) of the normal diffractive ring is calculated. As described above, the equation that holds in these radii R0, R1, R1a′R0a ′ is an equation in which R0 / R1 = R0 ′ / R1 ′ is R0 / R1 = R0a ′ / R1a ′. The radius R1 (1) (n = 1 to N) of the normal diffractive ring is calculated by executing the above calculation.

  After the process of step S810, the controller CT ends the execution of the measurement object diffraction ring measurement program in step S812. Then, using the radius R1 (n) (n = 1 to N) of the normal diffraction ring and the corresponding rotation angle θa (n) (n = 1 to N), the residual stress of the measurement object OB is determined by the cos α method. Calculated.

  As can be understood from the above description of the operation, according to the above-described embodiment, when the normal direction of the imaging plate 28 coincides with the X-ray emission direction by the processing of step S302 in FIG. The radius of the diffraction ring composed of a perfect circle of the reference object BOB to be imaged is calculated. 3, the distance from the rotation center of the imaging plate 28 for each predetermined angle representing the shape of the diffraction ring of the reference object BOB is detected. Further, the distance from the rotation center of the imaging plate 28 for each predetermined angle representing the shape of the diffraction ring of the measurement object OB is detected by the processing in steps S802 and S804 in FIG. Then, by the processing in step S810 in FIG. 10, the radius of the diffraction ring made of a perfect circle of the reference object BOB and the distance from the rotation center of the imaging plate 28 for each predetermined angle representing the shape of the diffraction ring of the reference object BOB. Is used to correct the distance from the rotation center of the imaging plate 28 for each predetermined angle representing the shape of the diffraction ring of the measurement object OB, so that the normal direction of the imaging plate 28 is the X-ray emission direction. If they match, the distance (radius of the regular diffractive ring) from the rotation center of the imaging plate for each predetermined angle representing the shape of the diffractive ring of the measurement object OB imaged on the imaging plate 28 is calculated. As a result, even if the normal direction of the imaging plate 28 does not coincide with the X-ray emission direction, the radius of the normal diffraction ring by the measurement object OB can be detected with high accuracy, so that the residual stress of the measurement object OB is detected. Can be measured accurately.

  3, two diffractive rings of the reference object BOB are imaged on the imaging plate 28 for each rotation angle position different by 180 degrees of the imaging plate 28, respectively. The shapes of the two diffractive rings of the imaged reference object BOB are detected by the processes of steps S104 and S112 in FIG. 3, and the diffraction of the reference object BOB is diffracted by the processes of steps S106, S114, and S118 of FIG. The center of gravity position of each ring is detected, and an intermediate point between the center positions of the two detected diffraction rings is detected as an X-ray emission point. Then, by the processing of step S808 in FIG. 10, using the detected X-ray emission point, the rotation from the rotation center of the imaging plate 28 for each predetermined angle representing the shape of the diffraction ring of the measurement object OB and the reference object BOB. The distance and the predetermined angle are corrected. As a result, even when the optical axis of the emitted X-ray does not coincide with the rotation axis, the radius of the normal diffraction ring described above is calculated after correcting for the error caused by the mismatch. Therefore, the residual stress of the measurement object OB can be measured with higher accuracy.

  Furthermore, in carrying out the present invention, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the object of the present invention.

  In the above embodiment, the distance from the imaging plate 28 to the reference object BOB when the diffraction ring of the reference object BOB is imaged and the imaging plate 28 to the measurement object OB when the diffraction ring of the measurement object OB is imaged. The error due to the difference between the two distances was not regarded as a problem. However, if the distance between the two is greatly different, the radial position of the imaging plate 28 where the diffraction ring of the reference object BOB is imaged and the radial position of the imaging plate 28 where the diffraction ring of the measurement object OB is imaged are large. In contrast, if the imaging plate 28 is distorted, the error may increase. When the deviation between the rotation center and the X-ray emission point is large, the corrected rotation angle θa (n) (n = 1 to N) corresponding to the diffraction ring of the measurement object OB described above and the reference diffraction The deviation from the corrected rotation angle θ0a (n) (n = 1 to N) corresponding to the ring (assuming that it is equal to θa (n) (n = 1 to N) in the above embodiment) becomes large, and the error is increased. It can grow. Therefore, when imaging the diffraction ring of the measurement object OB, the elevator 12 is moved up and down so that the distance is adjusted to be equal to the distance when the diffraction ring of the reference object BOB is imaged.

  Further, in the above embodiment, the table 27 is set at different rotational positions of 180 degrees, and the diffraction ring of the reference object BOB is imaged at the respective rotational positions, and an intermediate point between the two gravity center positions (points 180 degrees apart on the circumference). ) To obtain the X-ray emission point. However, as shown in FIG. 13B, the diffraction ring may be imaged at three different rotational positions, and the center of a circle having three centroid positions on the circumference may be obtained as the X-ray emission point. Alternatively, the diffraction ring may be imaged at four or more different rotational positions, and the center of a circle having four or more centroid positions on the circumference may be obtained as the X-ray emission point. In the case of imaging these three diffractive rings and four or more diffractive rings, the rotational positions may be equiangular intervals or different angular intervals. Furthermore, when the X-ray emission point is obtained by imaging the reference diffraction ring at two different rotational positions, the two different rotational positions do not necessarily have to be 180 degrees. In this case, the two centroid positions are two points on the circumference, and the angle between the two centroid positions and the center of the circle may be equal to the angle between the rotational positions of the imaging plate 28 when imaging the diffraction ring. .

  In the above embodiment, the center of gravity of the diffraction ring of the reference object BOB is obtained to obtain the X-ray emission point. However, when the imaging plate 28 is attached to the table 27, if there is no possibility that the imaging plate 28 is distorted and there is only a possibility that the imaging plate 28 is tilted, the diffraction ring is necessarily elliptical. Therefore, an elliptical focal position may be used instead of the barycentric position of the above embodiment. Further, a point where the major axes of the ellipses may be set as the X-ray emission point. It should be noted that these barycentric position, focal position, and long axis are determined by the shape of the diffraction ring and indicate information related to the position of the diffraction ring.

  In the above embodiment, the signal intensity S (n, m) and the radius r (n, m) are stored every time the rotation angle of the imaging plate 28 reaches a predetermined rotation angle. However, instead of this, the rotation angle θ (n, m), the signal intensity S (n, m), and the radius r (n, m) of the imaging plate 28 may be acquired and stored at predetermined time intervals. Good. In this case, in the diffraction ring shape detection process, the change in the signal intensity S in the radial direction at a predetermined rotation angle may be calculated by an interpolation method. Also by this, the same effect as the above embodiment can be obtained.

  Moreover, in the said embodiment, it is determined using the light reception position of the reflected light received by the light reception sensor 31 whether the position of the reference | standard object BOB and the measuring object OB in the height direction exists in a predetermined range. However, if it is not within the predetermined range, the operator adjusts the height of the elevating stage 12a. However, the height of the elevating stage 12a is automatically adjusted so that the positions in the height direction of the reference object BOB and the measurement object OB represented by the light receiving position of the light receiving sensor 31 are within a predetermined range. May be. According to this, as long as the position in the height direction of the reference object BOB and the measurement object OB set by the operator is within a range in which the light receiving sensor 31 can receive the reflected light, the operator can increase the height of the lifting stage 12a. Since there is no need to adjust the height, work efficiency can be improved. Note that the light receiving sensor 31 is not required if the distance between the imaging plate 28, the reference object BOB, and the measurement object OB is always constant as in the conventional X-ray diffractometer, for example.

  Further, in the above-described embodiment, the reading start position is determined using the light receiving position of the light receiving sensor 31 assuming a region where the radius of the imaged diffraction ring may deviate from the diffraction ring reference radius R0. did. However, the laser beam may always be irradiated to a certain region without using the diffraction ring reference radius R0. For example, the entire region of the imaging plate 28 may be irradiated with laser light. Similarly, the visible light emitted from the LED 52 may be always irradiated with a visible light emitted from the LED 52 to a certain area. For example, the entire region of the imaging plate 28 may be irradiated with visible light from the LED 52. However, in this case, the measurement time is longer than in the above embodiment.

  In the above embodiment, the laser detection device PUH is controlled by the focus servo. However, when the imaging plate 28 is rotated, the variation in the distance between the light receiving surface of the imaging plate 28 and the objective lens 39 is very small. If so, focus servo control is unnecessary.

  In the above embodiment, the laser light applied to the imaging plate 28 is a laser beam having a constant intensity. Instead of this, a preset high level intensity and a preset low level laser beam are used. A pulsed laser beam having repeated intensities may be used, and an instantaneous value of the SUM signal may be acquired at a timing when the intensity reaches a high level. In this case, a laser beam having a high level of intensity is instantaneously applied to a point at which the instantaneous value of the SUM signal of the imaging plate 28 is acquired. That is, in the state where the laser beam is directed to the point where the instantaneous value of the SUM signal is acquired, the intensity of the laser beam is at a low level, and almost no light is generated by the stimulated emission. Then, when approaching the point at which the instantaneous value of the SUM signal is obtained, the intensity of the laser beam becomes high and light due to the stimulated emission is generated. When laser light with a high level of intensity is always radiated, the intensity of the light decreases due to the continued generation of light due to the stimulated emission. However, if configured as described above, a large intensity of light is generated by the stimulated emission. At this timing, the instantaneous value of the SUM signal can be acquired.

DESCRIPTION OF SYMBOLS 13 ... X-ray emitter, 15 ... Moving stage, 18 ... Feed motor, 21 ... Position detection circuit, 24 ... Spindle motor, 26 ... Rotation angle detection circuit, 27 ... Table, 28 ... Imaging plate, 31 ... Light receiving sensor, 33 DESCRIPTION OF SYMBOLS ... Laser light source 34 ... Laser drive circuit 39 ... Objective lens 43 ... Photo detector 44 ... Amplifier circuit 48 ... SUM signal generation circuit 49 ... Conversion circuit 52 ... LED 54 ... Display device 55 ... Input device CT ... Controller

Claims (8)

An X-ray emitter that emits X-rays toward a target object;
A table in which a through hole for allowing the X-rays to pass through is formed in the center;
An imaging plate attached to the table and having a light receiving surface for receiving the diffracted light of the X-ray diffracted by the object;
A laser light source for emitting laser light and a photodetector for receiving laser light; irradiating the light receiving surface of the imaging plate with the laser light; and receiving light emitted from the imaging plate by the irradiation of the laser light A laser detector that outputs a received light signal according to the received light intensity;
Rotating means for rotating the table around the central axis of the through hole;
Rotation angle detection means for detecting a rotation angle from a reference position in rotation of the table by the rotation means;
Moving means for moving the table relative to the laser detection device in a direction parallel to the light receiving surface of the imaging plate;
A moving position detecting means for detecting a moving position of the table by the moving means;
The moving means is controlled to move the table, the X-ray emitter emits X-rays toward a reference object having a residual stress of “0”, and the imaging is performed by X-rays diffracted by the reference object First diffractive ring imaging means for imaging a diffractive ring of a reference object on a plate;
An imaging position of the laser beam emitted from the laser detection device on the imaging plate is controlled by rotating and moving the imaging plate on which the diffraction ring of the reference object is recorded by controlling the rotating means and moving means. While rotating around the center of the plate and changing in the radial direction, the received light signal output from the laser detection device is input, and received light intensity data representing the received light intensity represented by the input received light signal, The laser beam acquired from the rotation position detected by the rotation angle detection means and the movement position detected by the movement position detection means is sequentially read in association with the irradiation position on the imaging plate, and the laser beam is read based on the read light intensity data. Of the reference object formed on the imaging plate A first diffraction ring shape detection means for detecting a shape of Oriwa,
The moving means is controlled to move the table, irradiate X-rays from the X-ray emitter toward the measurement object, and the X-ray diffracted by the measurement object irradiates the measurement object on the imaging plate. A second diffraction ring imaging means for imaging the diffraction ring;
By controlling the rotating means and the moving means to rotate and move the imaging plate on which the diffraction ring of the measurement object is recorded, the irradiation position of the laser light emitted from the laser detection device on the imaging plate is determined. While rotating around the center of the imaging plate and changing in the radial direction, each received light reception signal output from the laser detection device, received light intensity data representing the light reception intensity represented by the input light reception signal, The laser beam obtained from the rotation position detected by the rotation angle detection means and the movement position detected by the movement position detection means is sequentially read in association with the irradiation position on the imaging plate, and based on the read light intensity data. Measurement object formed on the imaging plate A second diffraction ring shape detection means for detecting a diffraction ring shape,
The shape of the diffraction ring of the measurement object detected by the second diffraction ring shape detection unit is corrected using the shape of the diffraction ring of the reference object detected by the first diffraction ring shape detection unit, and the imaging An X-ray diffraction measurement apparatus comprising: correction means for reducing an influence of an attachment error of the plate to the table. The X-ray diffraction measurement apparatus according to claim 1,
The first diffractive ring imaging means controls the rotation means using the rotation angle detected by the rotation angle detection means, rotates the table, and sets the imaging plate at a predetermined angular position. Having setting means,
The second diffraction ring imaging means controls the rotation means using the rotation angle detected by the rotation angle detection means to rotate the table, and the imaging plate is rotated at a predetermined angle by the first angle position setting means. A second angular position setting means for setting the same angular position as the position;
The shape of the diffractive ring of the reference object detected by the first diffractive ring shape detection means is represented by the distance from the rotation center of the imaging plate for each predetermined angle,
The shape of the diffraction ring of the measurement object detected by the second diffraction ring shape detection means is represented by a distance from the rotation center of the imaging plate for each predetermined angle, and the correction means When the normal direction coincides with the X-ray emission direction, the radius of the diffraction ring made of a perfect circle of the reference object imaged on the imaging plate and the predetermined angle representing the shape of the diffraction ring of the reference object Using the ratio of the distance from the rotation center of the imaging plate to the distance from the rotation center of the imaging plate for each predetermined angle representing the shape of the diffraction ring of the measurement object, Represents the shape of the diffractive ring of the measurement object imaged on the imaging plate when the normal direction of is coincident with the X-ray emission direction An X-ray diffraction measurement apparatus comprising first correction means for calculating a distance from the rotation center of the imaging plate for each predetermined angle. The X-ray diffraction measurement apparatus according to claim 2,
The first diffractive ring imaging unit controls the rotation unit using the rotation angle detected by the rotation angle detection unit, and directs the X toward the reference object for each of a plurality of different rotation angle positions of the imaging plate. A plurality of diffraction rings of a reference object are respectively imaged on the imaging plate by X-rays radiated from a line emitter and diffracted by the reference object,
The first diffractive ring shape detecting means detects the shapes of a plurality of diffractive rings of a reference object imaged on the imaging plate, and the correcting means is
Fixed point axis detection means for respectively detecting a plurality of points or axes respectively determined from the shapes of the plurality of diffraction rings detected by the first diffraction ring shape detection means;
X-ray emission point detection means for detecting, as the X-ray emission point, a point where the optical axis of the X-ray emitted from the X-ray emitter intersects the imaging plate, using the detected plurality of points or axes. ,
The distance from the rotation center of the imaging plate for each predetermined angle representing the shape of the diffraction ring of the reference object, the distance from the rotation center of the imaging plate for each predetermined angle representing the shape of the diffraction ring of the measurement object And a second correcting means for correcting the predetermined angle using the detected X-ray emission point,
The X-ray diffraction measurement apparatus according to claim 1, wherein the calculation by the first correction unit is performed after the correction by the second correction unit. In the X-ray-diffraction measuring apparatus of Claim 3,
The first diffractive ring imaging means images two diffractive rings of a reference object on the imaging plate for each rotation angle position different by 180 degrees of the imaging plate,
The fixed point axis detecting means detects the position of the center of gravity of the two diffraction rings of the reference object from the shape of the two diffraction rings of the detected reference object,
The X-ray emission measuring device, wherein the X-ray emission point detecting means detects an intermediate point between the detected barycentric positions of the two diffraction rings as an X-ray emission point. In the X-ray-diffraction measuring apparatus of Claim 3,
The fixed point axis detecting means detects the positions of the center of gravity of the plurality of diffraction rings of the reference object from the shapes of the plurality of diffraction rings of the detected reference object,
The X-ray emission measuring device is characterized in that the X-ray emission point detection means detects a center position of a circle having a center of gravity of the detected plurality of diffraction rings on the circumference as an X-ray emission point. An X-ray emitter that emits X-rays toward a target object;
A table in which a through hole for allowing the X-rays to pass through is formed in the center;
An imaging plate attached to the table and having a light receiving surface for receiving the X-ray diffracted light diffracted by the object, and recording a diffraction ring that is an image of the diffracted light;
A laser light source for emitting laser light and a photodetector for receiving laser light; irradiating the light receiving surface of the imaging plate with the laser light; and receiving light emitted from the imaging plate by the irradiation of the laser light A laser detector that outputs a received light signal according to the received light intensity;
Rotating means for rotating the table around the central axis of the through hole;
Rotation angle detection means for detecting a rotation angle from a reference position in rotation of the table by the rotation means;
Moving means for moving the table relative to the laser detection device in a direction parallel to the light receiving surface of the imaging plate;
Applied to an X-ray diffraction measurement apparatus comprising a moving position detecting means for detecting a moving position of the table by the moving means;
The moving means is controlled to move the table, the X-ray emitter emits X-rays toward a reference object having a residual stress of “0”, and the imaging is performed by X-rays diffracted by the reference object A first diffractive ring imaging step of imaging a diffractive ring of a reference object on a plate;
An imaging position of the laser beam emitted from the laser detection device on the imaging plate is controlled by rotating and moving the imaging plate on which the diffraction ring of the reference object is recorded by controlling the rotating means and moving means. While rotating around the center of the plate and changing in the radial direction, the received light signal output from the laser detection device is input, and received light intensity data representing the received light intensity represented by the input received light signal, The laser beam acquired from the rotation position detected by the rotation angle detection means and the movement position detected by the movement position detection means is sequentially read in association with the irradiation position on the imaging plate, and the laser beam is read based on the read light intensity data. Of the reference object formed on the imaging plate A first diffraction ring shape detecting step of detecting the shape of Oriwa,
The moving means is controlled to move the table, irradiate X-rays from the X-ray emitter toward the measurement object, and the X-ray diffracted by the measurement object irradiates the measurement object on the imaging plate. A second diffraction ring imaging step of imaging the diffraction ring;
By controlling the rotating means and the moving means to rotate and move the imaging plate on which the diffraction ring of the measurement object is recorded, the irradiation position of the laser light emitted from the laser detection device on the imaging plate is determined. While rotating around the center of the imaging plate and changing in the radial direction, each received light reception signal output from the laser detection device, received light intensity data representing the light reception intensity represented by the input light reception signal, The laser beam obtained from the rotation position detected by the rotation angle detection means and the movement position detected by the movement position detection means is sequentially read in association with the irradiation position on the imaging plate, and based on the read light intensity data. Measurement object formed on the imaging plate A second diffraction ring shape detecting step of detecting a diffraction ring shape,
The shape of the diffraction ring of the measurement object detected by the second diffraction ring shape detection step is corrected using the diffraction ring shape of the reference object detected by the first diffraction ring shape detection step, and the imaging And a correction step for reducing an influence of an attachment error of the plate on the table. The X-ray diffraction measurement method according to claim 6,
In the first diffractive ring imaging step, a first angular position for controlling the rotation means using the rotation angle detected by the rotation angle detection means to rotate the table to set the imaging plate at a predetermined angular position. Having a setting step,
In the second diffractive ring imaging step, the rotation unit is controlled using the rotation angle detected by the rotation angle detection rotation unit to rotate the table, and the imaging plate is moved by the first angular position setting unit. A second angular position setting step for setting the same angular position as the angular position;
The shape of the diffractive ring of the reference object detected by the first diffractive ring shape detection step is represented by the distance from the rotation center of the imaging plate for each predetermined angle,
The shape of the diffraction ring of the measurement object detected by the second diffraction ring shape detection step is represented by a distance from the rotation center of the imaging plate for each predetermined angle, and the correction step is performed on the imaging plate. When the normal direction coincides with the X-ray emission direction, the radius of the diffraction ring made of a perfect circle of the reference object imaged on the imaging plate and the predetermined angle representing the shape of the diffraction ring of the reference object Using the ratio of the distance from the rotation center of the imaging plate to the distance from the rotation center of the imaging plate for each predetermined angle representing the shape of the diffraction ring of the measurement object, Represents the shape of the diffractive ring of the measurement object imaged on the imaging plate when the normal direction of is coincident with the X-ray emission direction An X-ray diffraction measurement method comprising: a first correction step of calculating a distance from the rotation center of the imaging plate for each predetermined angle. The X-ray diffraction measurement method according to claim 7,
In the first diffraction ring imaging step, the rotation unit is controlled using the rotation angle detected by the rotation angle detection unit, and the X is directed toward the reference object at each of a plurality of different rotation angle positions of the imaging plate. A plurality of diffraction rings of a reference object are respectively imaged on the imaging plate by X-rays radiated from a line emitter and diffracted by the reference object,
The first diffraction ring shape detection step detects the shape of each of the plurality of diffraction rings of the reference object imaged on the imaging plate, and the correction step includes
A fixed point axis detection step for detecting a plurality of points or axes respectively determined from the shapes of the plurality of diffraction rings detected by the first diffraction ring shape detection step, and respectively specifying the positions of the plurality of diffraction rings;
An X-ray emission point detecting step of detecting, as an X-ray emission point, a point where the optical axis of the X-ray emitted from the X-ray emitter intersects the imaging plate, using the detected plurality of points or axes; ,
The distance from the rotation center of the imaging plate for each predetermined angle representing the shape of the diffraction ring of the reference object, the distance from the rotation center of the imaging plate for each predetermined angle representing the shape of the diffraction ring of the measurement object And a second correction step of correcting the predetermined angle using the detected X-ray emission point,
The X-ray diffraction measurement method, wherein the calculation in the first correction step is performed after the correction in the second correction step.

Images