Calibrating Rotating Chromatic Range Sensor
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Solution Overview
Problem
Coordinate measurement machines using rotating optical pens face challenges with accurate calibration, particularly for correcting misalignment errors such as radius, azimuth angle, and Z distance errors, which are difficult to address using conventional methods like interferometers, especially in manufacturing facilities.
Innovation Solution
A method and system for calibrating a chromatic range sensor optical probe that includes a calibration object with a nominally cylindrical surface and angular reference features, allowing the probe to acquire radial distance data while rotating, which is then processed to generate calibration data for compensating measurement errors as a function of rotational angle, using a coordinate measurement machine with light generating and wavelength detection circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional interferometer calibration is used for rotating optical probes, then measurement accuracy can be improved, but the calibration process becomes difficult to perform accurately and is hard to execute at measurement sites
Solution Approach 1:
The patent introduces a calibration object with known geometric features (cylindrical surface, reference plane, angular reference features) as an intermediary between the interferometer and the rotating optical probe. This calibration object serves as a mediator that simplifies the calibration process by providing easily measurable reference features that can be accurately detected by the probe during rotation, eliminating the need for complex direct interferometer-to-probe calibration procedures at measurement sites
2Adaptability or versatility
If a rotating optical pen is used to take measurements, then versatility of measurement is improved, but misalignment errors such as radius, azimuth angle, and Z distance errors occur
Solution Approach 1:
The patent applies preliminary calibration action by using the calibration object to pre-determine correction values for misalignment errors before actual measurements are taken. The calibration process establishes correction data that compensates for radius, azimuth angle, and Z distance errors, allowing the rotating optical probe to maintain high accuracy throughout its versatile measurement operations without requiring real-time adjustment
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach provides improved accuracy in correcting misalignment errors, enhancing the precision of measurements taken by rotating chromatic range sensor configurations, thereby improving the reliability of coordinate measurement machines in manufacturing environments.
Implementation Method 1
chromatic range sensor optical probe... configured to direct a radial distance sensing beam... The optical probe uses chromatic dispersion to focus different wavelengths at different distances along a measurement axis
Implementation Method 2
angular reference features formed on or in the first nominally cylindrical calibration surface... configured to be sensed by the radial distance sensing beam
Data Source
AI summary
A calibration configuration for a chromatic range sensor (CRS) optical probe of a coordinate measurement machine (CMM) includes a calibration object. The calibration object includes at least a first nominally cylindrical calibration surface having a central axis that extends along a Z direction that is intended to be aligned approximately parallel to a rotation axis of the CRS optical probe. The first nominally cylindrical calibration surface is arranged at a known first radius R1 from the central axis that extends along the Z direction. A first set of angular reference features is formed on or in the first nominally cylindrical calibration surface. The angular reference features are configured to be sensed by the radial distance sensing beam and are located at known angles or known angular spacings around the central axis from one another on or in the first nominally cylindrical calibration surface.