Abstract: A measuring apparatus includes a light source emitting a measuring light, a first photo-detection element directly receiving a part of a reflected light of the measuring light reflected from a shaft to be measured to detect a first light receiving position, and a second photo-detection element directly receiving another part of the reflected light to detect a second light receiving position. An axis tilt angle of the shaft is measured on the basis of a signal output from the first photo-detection element and a signal output from the second photo-detection element.

Abstract: A measuring apparatus includes a light source emitting a measuring light, a first photo-detection element directly receiving a part of a reflected light of the measuring light reflected from a shaft to be measured to detect a first light receiving position, and a second photo-detection element directly receiving another part of the reflected light to detect a second light receiving position. An axis tilt angle of the shaft is measured on the basis of a signal output from the first photo-detection element and a signal output from the second photo-detection element.

Abstract: An eccentricity measuring instrument of polygon mirror motors includes a first light source, an optical position detecting element for detecting a position of first reflection light, i.e. first measuring light emitted from the first light source and reflected on the polygon mirror, a second light source, a photo detecting element for detecting a position of second reflection light, i.e. second measuring light emitted from the second light source and reflected on the polygon mirror; and an eccentricity calculator for calculating an output, at a detection of the second reflection light by the photo detecting element, from the optical position detecting element. The second measuring light forms a given angle with the second reflection light, and a plane formed by the first measuring light and the first reflection light intersects with a plane formed by the second measuring light and the second reflection light at right angles.

Abstract: An eccentricity measuring instrument of polygon mirror motors includes a first light source, an optical position detecting element for detecting a position of first reflection light, i.e. first measuring light emitted from the first light source and reflected on the polygon mirror, a second light source, a photo detecting element for detecting a position of second reflection light, i.e. second measuring light emitted from the second light source and reflected on the polygon mirror; and an eccentricity calculator for calculating an output, at a detection of the second reflection light by the photo detecting element, from the optical position detecting element. The second measuring light forms a given angle with the second reflection light, and a plane formed by the first measuring light and the first reflection light intersects with a plane formed by the second measuring light and the second reflection light at right angles.