Patent ID: 8212997

Claim:
A chromatic confocal point sensor optical pen operable to provide a signal usable to measure a distance to a surface, the chromatic confocal point sensor optical pen comprising: a housing; an aperture that outputs source radiation and receives reflected radiation; and a multi-stage optical configuration arranged along an optical axis of the chromatic confocal point sensor optical pen to receive the source radiation from the aperture, output it toward the surface as a focused measurement beam having axial chromatic dispersion, receive reflected radiation from the surface and focus the reflected radiation proximate to the aperture with axial chromatic dispersion, wherein: the multi-stage optical configuration comprises a plurality of axially dispersive focusing elements comprising: a first axially dispersive focusing element that receives source radiation and focuses that radiation at a first focal region internal to the multi-stage optical configuration, and a last axially dispersive focusing element that receives radiation from a last focal region internal to the multi-stage optical configuration and outputs the measurement beam; and at least the first and last axially dispersive focusing elements provide respective amounts of axial chromatic dispersion which contribute to increase the overall axial chromatic dispersion of the measurement beam.