Surface measurement instrument and calibration thereof
First Claim
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1. A method of characterising an eccentricity of a rotary encoder of a surface measurement instrument, the method comprising:
- effecting relative rotation of a work piece support and a measurement probe, wherein the rotation is effected about a rotation axis and the work piece support supports an artefact having an undulating profile;
using a rotary encoder to log, about a measurement axis of the rotary encoder, the rotation,wherein the measurement axis of the rotary encoder has an eccentricity with respect to the rotation axis;
measuring, using the measurement probe, the undulating profile of the artefact at a plurality of rotational positions of the work piece support with respect to the measurement probe to produce profile measurement data; and
extracting, by a processing unit, from the profile measurement data parameters describing the eccentricity of the measurement axis of the rotary encoder with respect to the rotation axis.
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Abstract
A method of calibrating a surface measurement instrument includes rotating a work piece having an undulating surface on a turntable of a metrological apparatus; measuring the surface of the work piece at a plurality of rotational positions; analyzing the results of the measurement to determine parameters describing an error causing characteristic of the metrological apparatus; and using the determined parameters to correct measurement data for the error causing characteristic of the metrological apparatus.
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Citations
18 Claims
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1. A method of characterising an eccentricity of a rotary encoder of a surface measurement instrument, the method comprising:
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effecting relative rotation of a work piece support and a measurement probe, wherein the rotation is effected about a rotation axis and the work piece support supports an artefact having an undulating profile; using a rotary encoder to log, about a measurement axis of the rotary encoder, the rotation, wherein the measurement axis of the rotary encoder has an eccentricity with respect to the rotation axis; measuring, using the measurement probe, the undulating profile of the artefact at a plurality of rotational positions of the work piece support with respect to the measurement probe to produce profile measurement data; and extracting, by a processing unit, from the profile measurement data parameters describing the eccentricity of the measurement axis of the rotary encoder with respect to the rotation axis. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 17, 18)
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16. A method of characterising an eccentricity of a rotary encoder of a surface measurement instrument, the method comprising:
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measuring, using a measurement probe, an undulating profile of an artefact carried on a work piece support at a plurality of rotational positions determined by logging, about a measurement axis of a rotary encoder, relative rotation about a rotation axis, of the work piece support with respect to the measurement probe, wherein the measurement axis of the rotary encoder has an eccentricity with respect to the rotation axis; receiving the profile measurement data by a processing unit; and extracting, by the processing unit, from the profile measurement data parameters describing the eccentricity of the measurement axis of the rotary encoder with respect to the rotation axis.
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Specification