US Patent 7131207 Workpiece inspection method

A method of inspecting an artefact using a non contact measurement mounted on a coordinate measuring apparatus. An artefact is measured first with a contact probe (28) and then with a non contact probe (32). An error map or function is generated (34) which corresponds to the difference between the measurements taken with the contact and non-contact probes. This error map or function may be used to calibrate the probe. Alternatively subsequent artefact may be measured with the non contact probe (36) and the error map or function used to correct the measurements (38).