Measuring the position of objects in space
AssigneeApre Instruments, LLC
InventorArtur Olszak
Life of this patent
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Abstract
Interference fringes in a bullseye pattern are produced by a measurement module by interfering a flat reference beam with a spherical beam reflected by a sphere connected to the tip of a probe in point contact with a test object. The bullseye interferogram is registered at a detector and analyzed conventionally to produce a position measurement of the tip of the probe. A beam correction module is used to align the bullseye interferogram with the illumination axis of the measurement module. By combining at least three such measurement modules in a coordinate measurement machine, the three-dimensional position of the probe and of its point contact with the test object can be obtained from analysis of the bullseye interferograms registered by the detectors with high precision and greatly reduced Abbe error.
Claims17
An interferometric system for measuring a position of an object in space, the system comprising:
- an interferometric measurement module configured to emit a test wavefront shaped as a diverging cone of light directed toward said object in space;
- a curved reflective surface placed within said cone of light such that a bullseye interferogram is produced and sensed by a detector;
- a processor programmed to produce a position measurement of said reflective surface based on the bullseye interferogram sensed by the detector;
- and
- a correction module adapted to align said bullseye interferogram with an illumination axis of the measurement module;
- wherein said reflective surface is attached to a probe in point contact with the object in space.
A coordinate measurement machine (CMM) comprising:
- at least three interferometric measurement modules configured to emit respective test wavefronts shaped as diverging cones of light;
- a curved reflective surface placed within said cones of light such that respective bullseye interferograms are produced and sensed by respective detectors,
- a processor programmed to produce a three-dimensional position measurement of said reflective surface based on the bullseye interferograms registered by the detectors;
- and
- correction modules adapted to align said bullseye interferograms with respective illumination axes of said measurement modules;
- wherein the reflective surface is attached to a probe of the CMM and the probe is adapted for three-dimensional motion in point contact with a measured object.
An interferometric method for measuring a position of an object in space, the method comprising the following steps:
- producing a test wavefront shaped as a diverging cone of light directed toward said object in space;
- placing a curved reflective surface connected to a probe within said cone of light such that a bullseye interferogram is produced and sensed by a detector;
- contacting the object with the probe;
- aligning said bullseye interferogram with an illumination axis of a measurement module;
- and
- producing a position measurement of said reflective surface based on interferometric analysis of the bullseye interferogram sensed by the detector.
Dependencies are inferred from the claim text.