Laser Scanner Calibration Using Retroreflectors for Geometric Error Correction
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Solution Overview
Problem
Scanner devices for positioning laser beams in processing fields often suffer from pincushion image distortion and geometric errors, making it challenging to project patterns accurately and in scale, which existing calibration methods do not adequately address.
Innovation Solution
The use of retroreflectors, such as transparent balls or retroreflective foils, in the processing field to detect the actual position of the laser beam and correct target positions, enhancing precision through high reflectance and intensity detection, allowing for accurate calibration of scanner devices in machining devices for three-dimensional component production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional calibration methods are used with standard reflective surfaces, then the calibration process can be performed, but the measurement precision is insufficient due to low signal intensity and high geometric errors
Solution Approach 1:
The patent changes the optical parameters of the calibration target by using retroreflective surfaces with high retroreflectance (≥90%) instead of standard reflective surfaces. This parameter change in reflectance特性 enables the detection system to capture sufficient signal intensity even at large angles, thereby achieving sub-pixel positioning precision (≤0.01 mm) and resolving the contradiction between measurement precision and calibration reliability
Solution Approach 2:
The patent introduces a retroreflector as an intermediary element between the laser beam and the detector. This retroreflector mediates the optical interaction by reflecting the laser beam back towards the scanner mirrors and detector with high efficiency, enabling accurate position detection without requiring direct line-of-sight between the laser source and detector, thus improving both measurement precision and calibration reliability
2Productivity
If scanner devices are used to position laser beams in processing fields, then laser processing can be performed, but pincushion image distortion and geometric errors occur making accurate pattern projection difficult
Solution Approach 1:
The patent implements a feedback mechanism where the retroreflector returns the laser beam to the scanner mirrors and detector, creating a closed-loop system. The detector measures the actual laser beam position and feeds this information back to the control system, which then corrects for pincushion distortion and geometric errors by adjusting the scanner mirror actuation signals, enabling accurate pattern projection while maintaining high laser processing productivity
Solution Approach 2:
The patent performs preliminary calibration action before actual laser processing. By using the retroreflector to map and correct geometric distortions in advance, the system establishes correction parameters that are applied during subsequent processing operations, ensuring both high productivity and manufacturing precision without requiring real-time correction during processing
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 method significantly improves the precision of laser beam positioning, reducing geometric errors and enabling distortion-free pattern projection by accurately determining and correcting the actual position of the laser beam, thus enhancing the quality of three-dimensional component production.
Implementation Method 1
detecting laser radiation that is reflected back into the scanner device as the laser beam passes over the retroreflector
Data Source
AI summary
The present disclosure relates to calibrating scanner devices for positioning laser beams in a processing field, and includes, e.g.: arranging a retroreflector in the processing field of the scanner device, the processing field being formed in a processing chamber for irradiating powder layers; detecting laser radiation reflected back into the scanner device when the laser beam passes over the retroreflector; determining an actual position of the laser beam in the processing field using the detected laser radiation; and calibrating the scanner device by correcting a laser beam target position specified for the scanner device in the processing field using the determined actual position of the laser beam in the processing field.