A cam portion (22) is attached to a first position (111) on a measurement target (110). A moving portion (24) is attached to a second position (112) on the measurement target (110) and is movable with respect to the cam portion (22) in an expanding/contracting direction of the measurement target (110). A strain portion (25) is attached to the moving portion (24) so as to fit along the measurement target (110), and is pressed against the cam portion (22). A strain of the strain portion (25) changes when the measurement target (110) expands or contracts and the moving portion moves (24) accordingly. An optical fiber sensor (10) has a temperature measurement portion (16) for measuring a temperature, and a strain measurement portion (17) for measuring a strain, and is attached to the strain portion (25).

A measurement device includes: a probe part including a probe configured to measure a surface of an object to be measured and is attached so as to swing around a swing center according to a shape of the surface of the object to be measured; a scale configured to measure displacement by swinging of the probe part; a scale head configured to read a scale mark of the scale; and an arm part to which the probe part is attached, the arm part is attached so as to swing around the swing center integrally with the probe part, and the scale is attached to the arm part. When thermal expansion coefficients of the probe part, the arm part and the scale are α, β and γ respectively, the measurement device satisfies a condition of

[00001]$\left(\alpha +\gamma \right)-1\text{}/\text{}2\alpha \text{}\le \text{}\beta \text{}\le \text{}\left(\alpha +\gamma \right)+1\text{}/\text{}2\alpha .$

A position measurement method is used by a device including an imaging unit and a position detector that detects a position of the imaging unit to measure, using a detection value at imaging of a measurement point, position coordinates of the measurement point. The method for correcting the detection value from the position detector includes obtaining, with the device, position coordinates of predetermined indices (22) arranged two-dimensionally on a calibration plate (20) as an actual measurement value, obtaining, as a correction value, a difference between the actual measurement value and a true value resulting from transformation of position coordinates of the indices (22) with respect to a reference point on the calibration plate (20), and correcting the detection value from the position detector (8, 9, 10). The imaging unit (3) images measurement points (P) on the measurement target (3) to measure position coordinates of the measurement points (P).

A coordinate measurement machine (CMM) includes a manually-positionable articulated arm. The articulated arm includes arm segments and rotary joints. At least one of the rotary joints includes a bearing assembly that comprises first and second bearings, a shaft that engages an inner race of the first bearing and an inner race of the second bearing, a housing that engages an outer race of the first bearing and an outer race of the second bearing, and a transducer configured to output an angle signal corresponding to an angle of rotation of the shaft relative to the housing. The shaft and the housing may be fabricated from materials having coefficients of thermal expansion selected to minimize change in moment rigidity and/or radial rigidity of the bearing assembly as the ambient temperature changes from the lower limit to the upper limit of the CMM operating ambient temperature range.

An optical dimensioning system includes one or more light emitting assemblies configured to project one or more predetermined patterns on an object; an imaging assembly configured to sense light scattered and/or reflected off the object, and to capture an image of the object while the patterns are projected; and a processing assembly configured to analyze the image of the object to determine one or more dimension parameters of the object. The light emitting assembly may include a single piece optical component configured for producing a first pattern and second pattern. The patterns may be distinguishable based on directional filtering, feature detection, feature shift detection, or the like. A method for optical dimensioning includes illuminating an object with at least two detectable patterns; and calculating dimensions of the object by analyzing pattern separate of the elements comprising the projected patterns. One or more pattern generators may produce the patterns.

A computer program product and to a method for compensating thermal errors in a mechanical process, the mechanical process in particular provided by a mechanical device such as a coordinate measuring machine, a tooling machine or an articulated robot arm. Thermal errors arise due to thermal disturbances affecting the mechanical process, wherein thermal disturbances may arise from environmental influences affecting the mechanical process or from internally generated changing temperature distributions.

An optical assembly (13) for a three-dimensional measurement device is equipped with: an optical lens (320) that forms a pair of conjugate planes having an optically conjugate relationship; an optical device (341) that is disposed on one of the pair of conjugate planes; a temperature sensor (354) for detecting the temperature of the optical lens (320); a heater (350) for heating the optical lens (320); and a control part that controls the operation of the heater (350) on the basis of the result of the detection made by the temperature sensor (354) such that the optical lens (320) reaches a constant temperature.

A position measurement method is used by a device including an imaging unit and a position detector that detects a position of the imaging unit to measure, using a detection value at imaging of a measurement point, position coordinates of the measurement point. The method for correcting the detection value from the position detector includes obtaining, with the device, position coordinates of predetermined indices (22) arranged two-dimensionally on a calibration plate (20) as an actual measurement value, obtaining, as a correction value, a difference between the actual measurement value and a true value resulting from transformation of position coordinates of the indices (22) with respect to a reference point on the calibration plate (20), and correcting the detection value from the position detector (8, 9, 10). The imaging unit (3) images measurement points (P) on the measurement target (3) to measure position coordinates of the measurement points (P).

A displacement sensor includes a coil which is mounted on a board and which is formed to have less than one turn, an inverter electrically connected to the coil, the inverter being configured to generate an oscillation signal, and a frequency detector electrically connected to the inverter, the frequency detector being configured to detect an oscillation frequency of an oscillator circuit including the coil and the inverter in accordance with a distance between a measurement object and the coil.

There is provided a probe unit correction method for correcting linear expansion of a probe unit to obtain an accurate measurement value. First, a probe offset value is calculated as a model. Then, a probe unit correction method includes a temperature data acquisition step of acquiring a temperature difference between a temperature at a time of calibration and a temperature of a current measurement environment, a reference tip coordinate correction step of calculating, as a reference tip correction coordinate value, a correction value of a reference tip coordinate value to which linear expansion is added, and a probe offset correction step of calculating, as a probe offset correction value, a correction value of a probe offset value to which the linear expansion is added.