Imaging Parameter Adjustment Using Laser Spot Geometry in 3D Printing
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Solution Overview
Problem
Adjusting operational parameters of imaging devices in additive manufacturing is challenging due to rapidly changing properties in the build plane, such as high dynamic changes in the intensity distribution, which falsify results from typical autofocusing methods like contrast-based or edge detection methods.
Innovation Solution
A method to determine and adjust imaging parameters by calculating the difference between actual and nominal spot parameters of the energy beam's extension in the build plane, allowing for precise adjustment of the focal position and other parameters, using a light source for safety and accuracy without generating an energy beam during the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If typical autofocusing methods (contrast-based or edge detection) are used, then the imaging device can be adjusted automatically, but the rapidly changing intensity distribution and flickering of the melt pool falsify the results and prevent accurate focusing
Solution Approach 1:
The patent changes the parameter used for autofocusing from intensity-based metrics (contrast, edge detection) to geometric metrics (spot area, circularity). By calculating the area and shape of the laser spot instead of relying on intensity gradients, the method achieves accurate focusing despite rapid intensity fluctuations and melt pool flickering, as these dynamic changes do not affect the geometric boundaries of the spot
Solution Approach 2:
The patent replaces the optical/intensity-based autofocusing mechanism with a geometric/image-processing-based mechanism. Instead of using contrast-based or edge-detection algorithms that rely on light intensity variations, the system uses spot area calculation and shape analysis, which are insensitive to intensity fluctuations caused by melt pool dynamics
2Loss of information
If the imaging device attempts to capture rapidly changing properties in the build plane, then complete process information can be obtained, but the high dynamic changes cause flickering that falsifies measurement results
Solution Approach 1:
The patent shifts from measuring intensity-based parameters (which are highly dynamic and unreliable) to geometric parameters such as spot area and circularity. These geometric parameters remain stable even when intensity fluctuates rapidly, providing reliable measurement data that reflects the actual laser spot characteristics without being corrupted by melt pool flickering
Solution Approach 2:
The patent extracts only the essential geometric information (spot area, shape) from the image data, ignoring the problematic intensity variations. By focusing solely on the boundaries and extent of the laser spot rather than its internal intensity distribution, the method obtains reliable process information without being affected by high-dynamic changes in the build plane
Data Source
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AI summary
Method for determining an operational parameter for an imaging device (12) for imaging at least one part of a build plane (6), in particular for a determination device (11) for determining at least one parameter of an energy beam (5) for an apparatus (1) for additively manufacturing three-dimensional objects (2), comprising the steps - determining at least one spot parameter that relates to an extension of a spot (10, 10'), in particular a spot (10, 10') of an energy beam (5), in a determination plane - determining a difference between the determined spot parameter and a nominal spot parameter - determining an imaging parameter of the imaging device (12) based on the determined difference - adjusting the imaging parameter based on the determined difference.