Mitutoyo Corporation

The University of Tokyo

Masato Kon

Hidemitsu Asano

Seiji Sasaki

Gyokubu Cho

Tomonori Goto

Jyota Miyakura

Yutaka Ohtake

Hiromu Maie

Sadayuki Matsumiya

Kozo Ariga

Hisayoshi Sakai

Yukie Nagai

Tasuku Ito

Nobuyuki Nakazawa

A calibration method for an X-ray measuring device includes mounting a calibration tool on a rotating table, identifying centroid positions from an output of an X-ray image detector, calculating projection transformation matrixes from the centroid positions and known relative positional intervals, repeating to identify the centroid positions from the output of the X-ray image detector and to calculate the projection transformation matrixes from the centroid positions and known relative positional intervals while the rotating table is rotated twice or more by a predetermined angle, and calculating a rotation center position of the rotating table on the basis of the projection transformation matrixes. The calibration method thereby allows easy calculation of the rotation center position of the rotating table on which an object to be measured is mounted in a rotatable manner, with the simple process.

Calibration method for X-ray measuring device

In measuring a dimension of an object to be measured W made of a single material, a plurality of transmission images of the object to be measured W are obtained by using an X-ray CT apparatus, and then respective projection images are generated. The projection images are registered with CAD data used in designing the object to be measured W. The dimension of the object to be measured W is calculated by using a relationship between the registered CAD data and projection images. In such a manner, high-precision dimension measurement is achieved by using several tens of projection images and design information without performing CT reconstruction.

Dimension measurement method using projection image obtained by X-ray CT apparatus

Volume data is generated by performing a CT scan with a spherical calibration jig having known dimensions in contact with an object. A profile of the surface shape of the object in the volume data is obtained, and a boundary surface of the spherical calibration jig is calculated from the center coordinates of the spherical calibration jig. A correction value for adjusting a boundary surface of the object determined from the gradient of the profile to the boundary surface of the spherical calibration jig is determined, and the boundary surface of the object is corrected by using the correction value. The shape of the object is determined by using the corrected boundary surface. The precision of measurement X-ray CT can thus be increased by accurately detecting the boundary surface of the object.

Calibration method and apparatus for measurement X-ray CT apparatus, measurement method and apparatus using the same, and measurement X-ray CT apparatus

A calibration method of an X-ray measuring device includes: a front-stage feature position calculation step of parallelly moving spheres disposed in N places a plurality of times, and identifying centroid positions ImPos(1 to Q)_Dis(1 to M)_Sphr_(1 to N) of projected images of the spheres in the N places; an individual matrix calculation step of calculating an individual projection matrix PPj (j=1 to Q) for each of the spheres; an individual position calculation step of calculating moving positions Xb of the spheres on the basis of the individual projection matrix PPj (j=1 to Q); a coordinate integration step of calculating specific relative position intervals X(1 to N) of the spheres; a rear-stage feature position calculation step; a transformation matrix calculation step of calculating a projective transformation matrix Hk (k=1 to Q); a rotation detection step; a position calculation step; and a center position calculation step.

Calibration method of x-ray measuring device

A calibration method of an X-ray measuring device includes: mounting a calibration toolon a rotating table; a moving position acquisition step of parallelly moving a position of an j-th spherewith respect to a position of a first sphere, irradiating the calibration toolwith an X-ray, and acquiring, form an output of an X-ray image detector, a moving position Mj where the magnitude of a differential position Erjofa centroid position ImDisjh_Sphr_j of a projected image of the j(2&#xa3;j&#xa3;N)-th spherewith respect to a centroid position ImDis1_Sphr_1 of a projected image of the first spherebecomes equal to or less than a specified value Vx; a relative position calculation step of performing the moving position acquisition step on the remaining spheres; a feature position calculation step; a transformation matrix calculation step; a rotation detection step; a position calculation step; and a center position calculation step.

A measurement X-ray CT apparatus calibrates a geometrical positional relationship between a focus of an X-ray source, an X-ray detector, and a rotation center of a rotating table in advance. The measurement X-ray CT apparatus then obtains projection images by irradiating the object to be measured with X-rays to perform a CT scan, and generates a three-dimensional image of the object to be measured by CT reconstruction of the projection images. The measurement X-ray CT apparatus further includes a reference frame that is made of a material and has a structure less susceptible to environmental changes, and sensors that are located on the reference frame and intended to successively obtain calibration values of the geometrical positional relationship between the focus of the X-ray source and the X-ray detector during the CT scan. The calibration values are used as parameters of the CT reconstruction.

Measurement X-ray CT apparatus

When measuring a mass-produced work piece using a measuring X-ray CT apparatus, which is configured to emit X-rays while rotating a work piece that is arranged on a rotary table and to reconstruct a projection image thereof to generate volume data of the work piece, the present invention assigns values to volume data for a predetermined work piece and stores the same as master data; obtains volume data for a mass-produced work piece under identical conditions to the predetermined work piece; measures the volume data and obtains an X-ray CT measured value for the mass-produced work piece; and corrects the X-ray CT measured value for the mass-produced work piece using the master data.

Measuring X-ray CT apparatus and production work piece measurement method

When generating a tomographic image using a measuring X-ray CT apparatus that is configured to emit X-rays while rotating a specimen that is arranged on a rotary table and reconstruct a projection image thereof to generate a tomographic image of the specimen, an amount of geometric error that is included in the projection image is obtained in advance and stored; the projection image is corrected using the stored amount of geometric error; and a tomographic image is reconstructed using the corrected projection image.

Measuring X-ray CT apparatus and tomographic image generating method

An isosurface mesh M is generated by extracting voxels having a certain CT value from volume data obtained by X-ray CT. A gradient vector g of a CT value is calculated at each vertex p of the isosurface mesh M. A plurality of sample points S are generated in positive and negative directions of the calculated gradient vector g. Gradient norms N of CT values at the respective generated sample points S are calculated. The vertex p of the isosurface mesh is moved and corrected to a sample point Sm having the maximum norm Nm calculated.

Surface extraction method and apparatus for X-ray CT volume

When generating a measurement plan for measuring X-ray CT that performs X-ray irradiation while rotating a test object, and in doing so acquires projection image data, reconstructs volume data from the projection image data, and measures a targeted measurement location in the volume data, the present invention calculates required measurement accuracy and a measurement field of view range based on tolerance information included in CAD data of the test object and a measurement location on the test object defined by a measurement operator ahead of time, and automatically generates, from this information, an optimized measurement plan that minimizes the number of measurements.

Method and apparatus for generating measurement plan for measuring X-ray CT

Projection images of reduced resolution are generated by reducing resolution of filtered projection images and/or reducing the number of filtered projection images. Volume data of reduced resolution is generated by performing CT reconstruction using the projection images of reduced resolution. Each voxel of the volume data of reduced resolution is provisionally divided. The provisionally divided voxels are compared in voxel value before and after provisional division. If a difference in voxel value before and after the provisional division is greater than a threshold, the provisional division is determined to be valid, and division is further continued. If the difference in voxel value before and after the provisional division is less than or equal to the threshold, the provisional division is determined to be invalid and the voxel ends being divided.

CT reconstruction method using filtered back projection

An X-ray CT measuring apparatus configured to emit an X-ray from an X-ray source while rotating a subject arranged on a rotary table, and obtain a tomographic image of the subject by reconstructing projection images, includes an imaging unit for imaging the subject on the rotary table from above or sideways, an obtaining unit for obtaining an image of the subject while rotating the subject, a calculating unit for calculating a maximum outer diameter of the subject during rotation by using the obtained image of the subject, and a setting unit for setting a movement limit of the rotary table on the basis of the maximum outer diameter.

X-ray CT measuring apparatus and interference prevention method thereof

A cross-section measurement method measures a cross section of a three-dimensional object formed by an object-forming machine that laminates an object material at an object-forming point. The object-forming machine includes: a table; an object-forming head; a beam supporting the object-forming head; a driver that moves the object-forming head relative to the table along the beam; an object-former on the object-forming head that laminates the object material on the table to form the object; and an imager on the object-forming head and that captures an image of the object. The object-former and the imager are indirectly supported by the beam via the object-forming head. The method includes: controlling the driver and the object-former to form the object on the table; capturing an image of the object with the imager while the object is being formed; and measuring a cross section of the object based on the captured image.

Object-forming machine, cross-section measurement apparatus, and cross-section measurement method

A 3D printer includes: an object-forming unit for forming an object by laminating an object material at an object-forming point based on a design data; an image capturing unit for capturing an image of the object formed by the object-forming unit; and a shape measurement unit for measuring a cross section of the object based on the image captured by the image capturing unit while the object is under formation by the object-forming unit.

An XY shift mechanism can shift a rotary table in a two-dimensional direction (XY direction) orthogonal to a rotation axis of the rotary table. By collaborative control of the shift position of the rotary table in the two-dimensional direction in synchronization with the rotation of the rotary table, rotation is made possible about a virtual rotation center that is set at an arbitrary position on the rotary table. The collaborative control of the shift position of the rotary table in the two-dimensional direction also corrects rotation eccentricity owing to the eccentricity of the rotary table. Thus, the virtual rotation center can be set at an arbitrary position on the rotary table, thus enabling obtainment of high resolution tomographic images of a plurality of regions of interest of an object, without the need for repositioning of the object.

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Kanagawa, Japan

Masato Kon