Patent ID: 8587772

Claim:
A chromatic point sensor (CPS) system configured to compensate for potential errors, including errors due to workpiece material effects, the CPS system comprising: a first confocal optical path including a longitudinally dispersive element, the first confocal optical path configured to focus different wavelengths at different distances proximate to a workpiece; a second optical path configured to focus different wavelengths at substantially the same distance proximate to the workpiece; a light source connected to input a first input spectral profile of wavelengths to the first confocal optical path; a light source connected to input a second input spectral profile of wavelengths to the second optical path; a first confocal optical path disabling element configured to prevent the first input spectral profile from being transmitted to a workpiece through the first confocal optical path; a second optical path disabling element configured to prevent the second input spectral profile from being transmitted to a workpiece through the second optical path; and 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 system is configured such that: when the first confocal path blocking element is not activated, the first input spectral profile is connected to the first confocal optical path, the first confocal optical path outputs corresponding radiation to the workpiece surface and receives first path reflected radiation from the workpiece surface, the first path reflected radiation having a first output spectral profile comprising a distance-dependent profile component having a peak that indicates a measurement distance from the first confocal optical path to the workpiece and a distance-independent profile component that includes a workpiece material component, and the CPS electronics provides corresponding first output spectral profile data; and when the second path blocking element is not activated, the second input spectral profile is connected to the second optical path, the second optical path outputs corresponding radiation to the workpiece surface and receives second path reflected radiation from the workpiece surface, the second path reflected radiation having a second output spectral profile comprising a distance-independent profile component that includes the workpiece material component, and the CPS electronics provides corresponding second output spectral profile data that is usable to compensate the first output spectral profile data for potential measurement distance errors comprising errors associated with the workpiece material component.