Chromatic range sensor probe detachment sensor

A method for detecting a detachment condition for a chromatic range sensor system that provides workpiece measurement information in a coordinate measuring machine, the method comprising:

• providing an optical pen for use in the chromatic range sensor system, the optical pen including an interchangeable optics element that comprises a chromatically dispersive optics portion and a detachment signal element, the detachment signal element being configured to substantially transmit a first set of wavelengths corresponding to a measuring range of the chromatic range sensor system, and at least partially reflect a set of detachment element wavelengths;
• detecting a detachment condition when the set of detachment element wavelengths are not being at least partially reflected, the detachment condition indicating that the interchangeable optics element has become detached from the optical pen;
• and
• providing a detachment indication signal when the detachment condition is detected.

An interchangeable optics element for an optical pen for use in a chromatic range sensor system that provides workpiece measurement information in a coordinate measuring machine (CMM), the optical pen comprising an optical pen base member that is fixed relative to a moving portion of the CMM and which includes and optical fiber that outputs source light that is transmitted through a confocal aperture, and receives reflected measurement signal light that is returned through the confocal aperture, the interchangeable optics element comprising:

• a mounting portion that is received by the optical pen base member for holding the interchangeable optics element in a fixed relationship relative to the base member;
• a chromatically dispersive optics portion configured to input source light from the confocal aperture, focus that light with longitudinal chromatic aberration along a measuring range, and return measurement signal light reflected from surfaces in the measuring range to the confocal aperture;
• and
• a detachment signal element that is positioned to receive the source light and is configure to:
• (a) substantially transmit a first set of wavelengths corresponding to the measuring range of the chromatic range sensor system;
• and
• (b) at least partially reflect a set of detachment signal element wavelengths to be returned back through the optical fiber, wherein the set of detachment signal element wavelenghts is detected by a set of detachment signal element wavelength sensing pixels that is not included in a set of pixels that sense the wavelengths corresponding to the measuring range.