Patent ID: 8587789

Claim:
A method for operating a chromatic point sensor (CPS) system to compensate for potential errors, including errors due to workpiece material effects, the method comprising: providing a CPS system comprising: an optical pen comprising a confocal optical path including a chromatically dispersive element and configured to focus different wavelengths at different distances proximate to a workpiece surface to be measured; a light source connected to provide an input spectral profile of wavelengths to the optical pen; a CPS electronics comprising a CPS wavelength detector comprising a plurality of pixels distributed along a measurement axis of the CPS wavelength detector, the plurality of pixels receiving respective wavelengths and providing output spectral profile data, wherein the CPS is configured such that when the optical pen is connected to the CPS electronics and operably positioned relative to the workpiece surface to perform measurement operations the optical pen inputs the input spectral profile and outputs corresponding radiation to the workpiece surface and receives reflected radiation from the workpiece surface and outputs reflected radiation to provide an output spectral profile to the CPS wavelength detector, the output spectral profile comprising a distance-dependent profile component having a wavelength peak that indicates a measurement distance from the optical pen to the workpiece surface and a distance-independent profile component that includes a workpiece material component corresponding to spectral profile effects associated with wavelength-dependent reflectivity variations of the material of the workpiece surface, and the CPS electronics provides corresponding output spectral profile data; and distance calibration data used to convert a distance-indicating coordinate corresponding to the wavelength peak to a corresponding distance measurement; and identifying a workpiece surface to be measured, wherein the method further comprises: operating at least the CPS electronics to define distance-independent profile component compensation data comprising data that are usable to compensate the output spectral profile data for potential measurement distance errors comprising errors associated with the workpiece material component corresponding to the identified workpiece surface.