Laser Beam Caustic Estimation from Raster Scan Frequency Signals
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Solution Overview
Problem
Current methods for determining irradiation parameters in additive manufacturing are cumbersome and time-consuming, requiring complex optical setups and multiple measurement positions to calibrate energy beams effectively.
Innovation Solution
A method involving generating an energy beam and guiding it across a structured test surface to detect emitted radiation, with parameters determined through Fourier transformation of the signal, allowing for efficient calibration of focus position and beam caustic without the need for extensive optical systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex optical systems are used to image beam cross-section onto a camera chip, then measurement precision of beam parameters is improved, but device complexity increases
Solution Approach 1:
The patent extracts only the essential measurement function from complex optical systems. Instead of using complete optical imaging systems with multiple lenses and cameras, the invention uses a simple detector to measure beam intensity at a single cross-section plane, extracting only the necessary information (beam width, position) through direct intensity measurement rather than full optical imaging.
Solution Approach 2:
The patent replaces complex mechanical optical systems with a simpler detection approach. Instead of mechanically positioning optical components to image the beam, the invention uses a stationary detector combined with signal processing (Fourier transformation of intensity traces) to determine beam parameters, substituting mechanical complexity with computational analysis.
2Measurement precision
If multiple measurement positions are used to determine parameters at different build plane locations, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The patent performs preliminary measurement at a single reference position to establish the relationship between detector signal characteristics and beam parameters. This preliminary calibration creates a reference model that can be used to determine parameters at any other position without requiring additional measurements, thus saving time while maintaining precision through the established reference framework.
Solution Approach 2:
The patent creates a reference measurement model at one position that serves as a template for determining parameters elsewhere. By copying the measurement approach and using the reference data to interpret measurements at different positions, the system achieves parameter determination across the build plane without physically moving to multiple measurement locations, reducing time loss while maintaining accuracy.
3Measurement precision
If scanning apertures are used to measure beam profile at multiple points, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts only the essential measurement capability from scanning aperture systems. Instead of using physical apertures that scan through multiple positions to map the beam profile, the invention uses a single stationary detector that measures intensity at one location, then derives the complete beam profile through Fourier transformation of the intensity trace, extracting full profile information without physical scanning components.
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 simplifies the calibration process by analyzing the frequency spectrum of the signal generated, enabling precise determination of irradiation parameters such as focus position and beam width, reducing the complexity and time required for calibration across the build plane.
Implementation Method 1
generating a signal by detecting radiation that is emitted, in particular reflected, from the test surface
Implementation Method 2
determining the at least one parameter based on a frequency spectrum of the signal, in particular based on a Fourier transformation of the signal
Data Source
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AI summary
Methods of determining at least one parameter of an irradiation device of an apparatus for additively manufacturing three-dimensional objects may include generating an energy beam and guiding the energy beam across a structured test surface, generating a signal by detecting radiation that is emitted from the test surface, and determining the at least one parameter based on a frequency spectrum of the signal.