Calibrating Coordinate Measuring Apparatus Scale Error with Laser Interferometer
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Solution Overview
Problem
Coordinate measuring apparatuses face challenges in accurately measuring intervals between reference balls due to scale errors, leading to inaccuracies in calibration.
Innovation Solution
A calibration method involving a structure with a reflector and laser interferometer to determine scale errors by measuring distances and coordinates at different positions, allowing for correction of interval measurements between reference objects, thereby improving calibration accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a coordinate measuring apparatus is used to measure the interval between reference balls, then the calibration process can be performed, but scale errors cause low measurement accuracy
Solution Approach 1:
A laser interferometer is introduced as an intermediary device to measure the movement of the stage in the measurement direction. The interferometer provides a reference standard for position measurement, allowing the scale error of the coordinate measuring apparatus to be calculated by comparing its measurements with the interferometer's measurements of the same stage displacement.
Solution Approach 2:
The mechanical measurement system of the coordinate measuring apparatus is supplemented by an optical measurement system (laser interferometer). The interferometer uses laser interference patterns to measure stage position with high precision, replacing the mechanical coordinate measurement system to provide a reference for error correction.
2Ease of operation
If scale error exists in the coordinate measuring apparatus, then the apparatus can still perform measurements, but the measured interval cannot be trusted
Solution Approach 1:
The system calculates the scale error by comparing the coordinate measuring apparatus's stage position measurements with the laser interferometer's measurements. This feedback mechanism allows the scale error to be quantified and used to correct subsequent measurements, maintaining measurement capability while improving accuracy through error compensation.
Solution Approach 2:
The measurement process incorporates a correction parameter (scale error) that is calculated based on the difference between the coordinate measuring apparatus readings and the interferometer readings. This parameter change approach allows the system to account for systematic errors and produce accurate measurement results despite the presence of scale error in the original measurement system.
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
Enhances the accuracy of calibrating intervals between reference objects by accounting for scale errors in the coordinate measuring apparatus, resulting in precise measurements.
Implementation Method 1
measuring a first distance from a laser interferometer to the reflector by having the laser interferometer irradiate the reflector with a laser beam
Implementation Method 2
measuring a first distance from a laser interferometer to the reflector by having the laser interferometer irradiate the reflector with a laser beam
Data Source
AI summary
A calibration method includes the steps of placing a structure to be measured at a first position, measuring a first distance from a laser interferometer to a reflector, and measuring first coordinates of a body to be measured, moving the structure to be measured to a second position, measuring a second distance from the laser interferometer to the reflector and measuring second coordinates of the structure to be measured with the coordinate measuring apparats, while the structure to be measured is at the second position, determining a scale error of the reference instrument, mounting the reference instrument, measuring the interval between objects to be measured, and calculating a calibration value of the interval between the objects to be measured.