Flatness Calibration Using Twist Correction Factors
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Solution Overview
Problem
Existing flatness calibration methods face challenges in accurately combining measurement data from line shapes in the X and Y directions due to twist errors at intersection points, especially when fine dust adheres or drift occurs, leading to measurement inaccuracies.
Innovation Solution
A method involving a rectangular parallelepiped-shaped bar mirror that is moved and rotated in the XY plane to measure flatness at multiple positions, with data alignment and correction in the Z-direction to minimize twist errors, using a synthesis plane calculator and twist correction factor determiner to generate a corrected flatness calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If measurement data in line shapes in X and Y directions are combined to perform flatness calibration, then measurement coverage is improved, but twist errors at intersection points cause measurement inaccuracies
Solution Approach 1:
The patent introduces an intermediary correction process that uses measurement data from diagonal directions as a mediator to identify and correct twist errors at intersection points. The diagonal measurement data serves as a reference to detect deviations in the orthogonal measurement data, enabling accurate correction of the intersection point errors while maintaining the benefits of combined X and Y direction measurements.
2Area of stationary object
If a large reference plane mirror is used to cover the measurement range, then measurement range is improved, but distortion in the mirror increases calibration difficulty
Solution Approach 1:
The patent segments the measurement process into multiple orthogonal passes (X and Y directions) with a smaller bar mirror, avoiding the need for a single large reference plane mirror. By dividing the measurement task into sequential line-by-line measurements that are later synthesized, the system achieves full measurement range coverage while using only a small, highly accurate mirror segment at any given time.
3Device complexity
If measurement data is corrected only at intersection points, then correction process is simplified, but errors from dust or drift at intersections are not adequately addressed
Solution Approach 1:
The patent uses diagonal direction measurement data as an intermediary reference to detect and correct errors at intersection points. By comparing orthogonal measurement data with diagonal reference data, the system can identify errors caused by dust or drift without requiring complex multi-parameter correction models, thus maintaining simplicity while improving accuracy.
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
There is a flatness calibration method in which a measurement data obtaining device (52) obtains measurement data when moving a bar mirror (9a) in a rectangular parallelepiped shape in an X-direction and a Y-direction, a data moving unit (53) moves the measurement data in a line shape in the X-direction and Y-direction in a Z-direction, a synthesis plane calculator (54) generates a synthesis plane (39) by synthesizing the measurement data, a twist correction factor determiner (55) determines a twist correction factor to minimize a twist correction amount in the Z-direction at a lattice point, a corrector (56) corrects the twist correction amount of the synthesis plane by using the twist correction factor, and flatness is calibrated by using the twist correction amount corrected by the corrector.