Abstract: An interchangeable chromatic range sensor (CRS) probe for a coordinate measuring machine (CMM). The CRS probe is capable of being automatically connected to a CMM under program control. In one embodiment, in order to make the CRS probe compatible with a standard CMM auto exchange joint, all CRS measurement light transmitting and receiving elements (e.g., the light source, wavelength detector, optical pen, etc.) are included in the CRS probe assembly. The CRS probe assembly also includes an auto exchange joint element that is attachable through a standard auto exchange joint connection to a CMM. In one embodiment, in order to provide the required signals through the limited number of connections of the standard CMM auto exchange joint (e.g., 13 pins), a low voltage differential signaling (LVDS) serializer may be utilized for providing additional control and data signals on two signal lines.

Abstract: An optical pen for use in a chromatic range sensor (CRS) may be used in a probe system for a coordinate measuring machine (CMM). The optical pen includes a confocal optical path, an interchangeable optics element, an optical pen base member, and a repeatable fast exchange mount. The confocal optical path includes a confocal aperture and a chromatically dispersive optics portion. The interchangeable optics element includes the chromatically dispersive optics portion. The optical pen base member includes an external mounting surface for mounting to an external reference frame. The repeatable fast exchange mount includes a first mating half located on the base member and a second mating half located on the interchangeable optics element. The repeatable fast exchange mount is configured to allow the base member to receive and hold the interchangeable optics element in a fixed relationship relative to the base member and the external reference frame.

Abstract: An interchangeable chromatic range sensor (CRS) probe for a coordinate measuring machine (CMM). The CRS probe is capable of being automatically connected to a CMM under program control. In one embodiment, in order to make the CRS probe compatible with a standard CMM auto exchange joint, all CRS measurement light transmitting and receiving elements (e.g., the light source, wavelength detector, optical pen, etc.) are included in the CRS probe assembly. The CRS probe assembly also includes an auto exchange joint element that is attachable through a standard auto exchange joint connection to a CMM. In one embodiment, in order to provide the required signals through the limited number of connections of the standard CMM auto exchange joint (e.g., 13 pins), a low voltage differential signaling (LVDS) serializer may be utilized for providing additional control and data signals on two signal lines.

Abstract: A chromatic point sensor system configured to compensate for potential errors due to workpiece material effects comprises a first confocal optical path including a longitudinally dispersive element 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 the first confocal optical path; a light source connected to the second optical path; a first confocal optical path disabling element; a second optical path disabling element; and a CPS electronics comprising a CPS wavelength detector which provides output spectral profile data. The output spectral profile data from the second optical path is usable to compensate output spectral profile data from the first confocal optical path for a distance-independent profile component that includes errors due to workpiece material effects.

Abstract: A method of error compensation in a chromatic point sensor (CPS) reduces errors associated with varying workpiece spectral reflectivity. The errors are associated with a distance-independent profile component of the CPS measurement signals. Workpiece spectral reflectivity may be characterized using known spectral reflectivity for a workpiece material, or by measuring the workpiece spectral reflectivity using the CPS system. CPS spectral reflectivity measurement may comprise scanning the CPS optical pen to a plurality of distances relative to a workpiece surface and determining a distance-independent composite spectral profile from a plurality of resulting wavelength peaks.

Abstract: A chromatic point sensor system configured to compensate for potential errors due to workpiece material effects comprises a first confocal optical path including a longitudinally dispersive element 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 the first confocal optical path; a light source connected to the second optical path; a first confocal optical path disabling element; a second optical path disabling element; and a CPS electronics comprising a CPS wavelength detector which provides output spectral profile data. The output spectral profile data from the second optical path is usable to compensate output spectral profile data from the first confocal optical path for a distance-independent profile component that includes errors due to workpiece material effects.

Abstract: A method of error compensation in a chromatic point sensor (CPS) reduces errors associated with varying workpiece spectral reflectivity. The errors are associated with a distance-independent profile component of the CPS measurement signals. Workpiece spectral reflectivity may be characterized using known spectral reflectivity for a workpiece material, or by measuring the workpiece spectral reflectivity using the CPS system. CPS spectral reflectivity measurement may comprise scanning the CPS optical pen to a plurality of distances relative to a workpiece surface and determining a distance-independent composite spectral profile from a plurality of resulting wavelength peaks.

Abstract: A fixed wavelength absolute distance interferometer including a first interferometer comprising a first light source transmitting a first light beam having a wavelength W toward a measurement target, a wavefront radius detector configured to provide a first measurement responsive to the wavefront radius at the wavefront radius detector, and a first path length calculating portion calculating a coarse resolution absolute path length measurement R; and a second interferometer comprising a beam transmitting device transmitting a second-interferometer light beam having a wavelength ?, a beam splitting/combining device separating the second-interferometer light beam into reference and measurement beams and combining the returning reference and measurement beams into a combined beam, a second-interferometer detector configured to receive the combined beam and provide signals of a phase ? of the combined beam, and a second path length calculating portion configured to determine a medium resolution absolute path leng

Abstract: A fixed wavelength absolute distance interferometer including a first interferometer comprising a first light source transmitting a first light beam having a wavelength W toward a measurement target, a wavefront radius detector configured to provide a first measurement responsive to the wavefront radius at the wavefront radius detector, and a first path length calculating portion calculating a coarse resolution absolute path length measurement R; and a second interferometer comprising a beam transmitting device transmitting a second-interferometer light beam having a wavelength ?, a beam splitting/combining device separating the second-interferometer light beam into reference and measurement beams and combining the returning reference and measurement beams into a combined beam, a second-interferometer detector configured to receive the combined beam and provide signals of a phase ? of the combined beam, and a second path length calculating portion configured to determine a medium resolution absolute path leng

Abstract: In a chromatic point sensor, distance measurements are based on a distance-indicating subset of intensity profile data, which is selected in a manner that varies with a determined peak position index coordinate (PPIC) of the profile data. The PPIC indexes the position a profile data peak. For profile data having a particular PPIC, the distance-indicating subset of the profile data is selected based on particular index-specific data-limiting parameters that are indexed with that same particular PPIC. In various embodiments, each set of index-specific data-limiting parameters indexed with a particular PPIC characterizes a distance-indicating subset of data that was used during distance calibration operations corresponding to profile data having that PPIC. Distance-indicating subsets of data may be compensated to be similar to a corresponding distance-indicating subset of data that was used during calibration operations, regardless of overall intensity variations and detector bias signal level variations.

Abstract: Methods for providing compensation for non-uniform response of a light source and wavelength detector subsystem of a chromatic point sensor (CPS) are provided. Light from the light source is input into an optical path that bypasses the measurement path through a CPS optical pen and provides the bypass light to the wavelength detector to provide a raw intensity profile distributed over the pixels of detector. The resulting set of raw intensity profile signals are analyzed to determine a set of error compensation factors for wavelength-dependent intensity variations that occur in the raw intensity profile signals. Later, the error compensation factors may be applied to reduce distortions and asymmetries that may otherwise occur in the shape of the signals in the peak region of CPS distance measurement profile signal data. The disclosed methods may provide enhanced accuracy, robustness, field-testing, and interchangeability for CPS components, in various embodiments.

Abstract: A chromatic point sensor (CPS) calibration object and characterizing data are provided. The calibration object comprises a flat base plane with steps extending from it. Step measurement points provided by the steps and base plane measurement points provided by portions of the base plane are intermingled along a measurement track. The characterizing data characterizes known heights of the measurement points. A calibration method acquires measurement data such that some base plane measurement points should be at nearly the same measurement distance and therefore have the same common mode errors relative to known base plane measurement point heights. If such base plane measurement points exhibit minimal error variations, then measurements for those and proximate measurement points may provide reliable calibration data. In contrast, error variations outside an expected range indicate unreliable measurements that should be screened or replaced by new calibration measurements.

Abstract: Methods for providing compensation for non-uniform response of a light source and wavelength detector subsystem of a chromatic point sensor (CPS) are provided. Light from the light source is input into an optical path that bypasses the measurement path through a CPS optical pen and provides the bypass light to the wavelength detector to provide a raw intensity profile distributed over the pixels of detector. The resulting set of raw intensity profile signals are analyzed to determine a set of error compensation factors for wavelength-dependent intensity variations that occur in the raw intensity profile signals. Later, the error compensation factors may be applied to reduce distortions and asymmetries that may otherwise occur in the shape of the signals in the peak region of CPS distance measurement profile signal data. The disclosed methods may provide enhanced accuracy, robustness, field-testing, and interchangeability for CPS components, in various embodiments.

Abstract: In a chromatic point sensor, distance measurements are based on a distance-indicating subset of intensity profile data, which is selected in a manner that varies with a determined peak position index coordinate (PPIC) of the profile data. The PPIC indexes the position a profile data peak. For profile data having a particular PPIC, the distance-indicating subset of the profile data is selected based on particular index-specific data-limiting parameters that are indexed with that same particular PPIC. In various embodiments, each set of index-specific data-limiting parameters indexed with a particular PPIC characterizes a distance-indicating subset of data that was used during distance calibration operations corresponding to profile data having that PPIC. Distance-indicating subsets of data may be compensated to be similar to a corresponding distance-indicating subset of data that was used during calibration operations, regardless of overall intensity variations and detector bias signal level variations.

Abstract: A fiber interface configuration for a chromatic point sensor optical pen is provided wherein a detector aperture element provides an aperture that is smaller than the light-transmitting core diameter of an optical fiber that is connected to the optical pen. The detector aperture element is fixed relative to the chromatically dispersive optics of the optical pen, the optical fiber abuts the aperture element, and the optical fiber core is aligned to the aperture. The aperture element and the end of the fiber may be inclined relative to the axis of the fiber, to deflect spurious reflections away from the optical signal path. The configuration provides high measuring resolution without using a tapered optical fiber, and provides interchangeability of the optical fiber connected to the optical pen.

Abstract: A chromatic point sensor (CPS) calibration object and characterizing data are provided. The calibration object comprises a flat base plane with steps extending from it. Step measurement points provided by the steps and base plane measurement points provided by portions of the base plane are intermingled along a measurement track. The characterizing data characterizes known heights of the measurement points. A calibration method acquires measurement data such that some base plane measurement points should be at nearly the same measurement distance and therefore have the same common mode errors relative to known base plane measurement point heights. If such base plane measurement points exhibit minimal error variations, then measurements for those and proximate measurement points may provide reliable calibration data. In contrast, error variations outside an expected range indicate unreliable measurements that should be screened or replaced by new calibration measurements.

Abstract: A fiber interface configuration for a chromatic point sensor optical pen is provided wherein a detector aperture element provides an aperture that is smaller than the light-transmitting core diameter of an optical fiber that is connected to the optical pen. The detector aperture element is fixed relative to the chromatically dispersive optics of the optical pen, the optical fiber abuts the aperture element, and the optical fiber core is aligned to the aperture. The aperture element and the end of the fiber may be inclined relative to the axis of the fiber, to deflect spurious reflections away from the optical signal path. The configuration provides high measuring resolution without using a tapered optical fiber, and provides interchangeability of the optical fiber connected to the optical pen.

Abstract: A range sensor using structured light intensity for determining displacement measurements. A micro-lens array or diffractive optical element inputs light from a light source and outputs a flattop intensity pattern in a diverging light stripe. By using a diverging light stripe, the response of the system to a change in position is made to vary approximately proportionally to the inverse of a distance from a reflecting surface to the source of the diverging light stripe. A dual detector approach may be utilized to eliminate the sensitivity of measurement signal with respect to variations in the optical power the light source, as well as other potential variations.

Abstract: A detector for interferometric distance or displacement measurement. The detector may receive orthogonally polarized object and reference path output beams, which are directed to a polarization-sensitive beam deflecting element. The beam deflecting element deflects one or both orthogonally polarized beams to provide a desired divergence angle between the beams. The diverging beams are input to a mixing polarizer. The beams exiting the mixing polarizer are similarly polarized and therefore interfere. The interfering diverging beams form interference fringes. The spatial phase of the fringes relative to a photodetector array characterizes the phase difference between the object and reference beams of the interferometer.