3D Laser Scanner Calibration Using Actuation Error Correction
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Solution Overview
Problem
High-speed, high-resolution galvanometric laser scanning systems face challenges in achieving accurate optical calibration due to errors in construction tolerances and target positioning, limiting the ability to achieve sub-micron accuracy in laser beam positioning across the field of regard.
Innovation Solution
A method and apparatus for calibrating laser scanning systems using a computational model that maps scan optic actuation to spatial coordinates, incorporating error correction tables and actuation rate adjustments to predictively adjust mirror rotations, enabling sub-micron accuracy by correcting positional errors through a calibration process involving a coordinate measurement machine and fiducials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high resolution laser scanning is implemented, then mirror actuator resolution of less than 10 μrad is required, but construction tolerances and target positioning errors make achieving such resolution difficult in practice
Solution Approach 1:
The patent performs preliminary calibration by measuring actual beam positions at multiple field locations and storing correction values in a lookup table before actual laser processing. This preliminary measurement and correction data storage resolves the contradiction by compensating for construction tolerances and positioning errors that would otherwise prevent achieving sub-10 μrad resolution in practice.
Solution Approach 2:
The patent implements feedback through an iterative calibration process where beam positions are measured, correction values are calculated and stored, then the system re-scans using these corrections to verify improvement. This feedback loop continues until convergence, ensuring that the actual beam position accuracy meets the required resolution despite initial construction tolerances and positioning errors.
2Measurement precision
If calibration is performed across the entire field of regard, then comprehensive error correction is achieved, but calibration time and computational resources increase
Solution Approach 1:
The patent segments the field of regard into multiple discrete locations rather than attempting continuous calibration across the entire field. By selecting specific representative points (e.g., corners, center, edges) and measuring corrections only at these segmented locations, the system achieves comprehensive error correction while significantly reducing calibration time and computational resources compared to full-field calibration.
Data Source
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AI summary
A method includes determining a set of pattern position errors between (i) a set of expected pattern positions of a calibration pattern on a laser target situated in a laser processing field of a laser system and produced based on a set of initial scan optic actuation corrections associated with a scan optic of the laser system and (ii) a set of measured pattern positions of the calibration pattern, determining a set of scan optic actuation rates based on the set of initial scan optic actuation corrections, and updating the set of initial scan optic actuation corrections based on the set of scan optic actuation rates and the set of pattern position errors so as to form a set of updated scan optic actuation corrections that is associated with a reduction of at least a portion of the set of pattern position errors.