Abstract: In order to sufficiently capture spatial distortion specific to an X-ray CT device and evaluate the three-dimensional shape measurement accuracy of the X-ray CT device, in a utensil, by attaching support rods fixing spheres to the tip thereof and having different lengths to a base spheres are arranged in an XYZ space on the base. On a flat surface on the top of the base, the support rods supporting the spheres and having different lengths are arranged at predetermined intervals. In doing so, the spheres are arranged in the XYZ space respectively at appropriate inter-sphere distances.

Abstract: In order to sufficiently capture spatial distortion specific to an X-ray CT device and evaluate the three-dimensional shape measurement accuracy of the X-ray CT device, in a utensil, by attaching support rods fixing spheres to the tip thereof and having different lengths to a base spheres are arranged in an XYZ space on the base. On a flat surface on the top of the base, the support rods supporting the spheres and having different lengths are arranged at predetermined intervals. In doing so, the spheres are arranged in the XYZ space respectively at appropriate inter-sphere distances.

Abstract: In order to sufficiently capture spatial distortion specific to an X-ray CT device and evaluate the three-dimensional shape measurement accuracy of the X-ray CT device, in a utensil, by attaching support rods fixing spheres to the tip thereof and having different lengths to a base spheres are arranged in an XYZ space on the base. On a flat surface on the top of the base, the support rods supporting the spheres and having different lengths are arranged at predetermined intervals. In doing so, the spheres are arranged in the XYZ space respectively at appropriate inter-sphere distances.

Abstract: A laser tracking interferometric length measuring instrument has a laser source and a tracking articulating optical lever provided on an optical path of an interferometric optical system. To track a retroreflector, the optical lever reflects a laser beam at the retroreflector, which reflects the beam back to the optical lever. This beam is reflected onto a quadrant photodiode. An attitude control means is used to control the attitude of the optical lever so that the laser beam reflected by the optical lever falls on the neutral point of the photodiode.

Abstract: A laser tracking interferometric length measuring instrument has a laser source and a tracking articulating optical lever provided on an optical path of an interferometric optical system. To track a retroreflector, the optical lever reflects a laser beam at the retroreflector, which reflects the beam back to the optical lever. This beam is reflected onto a quadrant photodiode. An attitude control means is used to control the attitude of the optical lever so that the laser beam reflected by the optical lever falls on the neutral point of the photodiode.

Abstract: A laser tracking interferometric length measuring instrument has a laser source and a tracking articulating optical lever provided on an optical path of an interferometric optical system. To track a retroreflector, the optical lever reflects a laser beam at the retroreflector, which reflects the beam back to the optical lever. This beam is reflected onto a quadrant photodiode. An attitude control means is used to control the attitude of the optical lever so that the laser beam reflected by the optical lever falls on the neutral point of the photodiode.

Abstract: A ball step gauge includes a gauge framework that is H-shaped in cross-section and has a horizontal frame. A plurality of holes are formed at predetermined intervals in the horizontal frame in an axial direction of the horizontal frame. A plurality of grooves are formed around each of the holes. A plurality of balls are inserted under pressure in the holes, with centers of the balls existing on a neutral axis of moment of inertia of an area of the gauge framework. Since the ball intervals are less liable to change, the ball step gauge can be used as a reliable standard gauge for calibrating coordinate measuring machines.

Abstract: A laser tracking interferometric length measuring instrument has a laser source and a tracking articulating optical lever provided on an optical path of an interferometric optical system. To track a retroreflector, the optical lever reflects a laser beam at the retroreflector, which reflects the beam back to the optical lever. This beam is reflected onto a quadrant photodiode. An attitude control means is used to control the attitude of the optical lever so that the laser beam reflected by the optical lever falls on the neutral point of the photodiode.

Abstract: While the three angles of a plate supporting an optical element, including rolling, pitching and yawing angles, are adjusted, the height of an upper plate of a conventional adjusting device changes. In order to solve this problem, small balls of adjusting screws engaged with a middle plate are made to be abut on three V-shaped concave plates formed on an upper plate, and a spring is extended between spring hooks of the upper plate and middle plate to make the upper and middle plate be forced near each other. By rotating the three adjusting screws, the three angles of the upper plate can be adjusted, and the distance between the upper surface of the upper plate and the lower surface of the lower plate can be adjusted. The middle plate is rotatively supported by the lower plate, and by rotating the projecting shaft of the middle plate, the optical element can be rotated about its optical axis.