Optical System Calibration via Scanner-Based Beam Path Alignment
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Solution Overview
Problem
Existing methods for calibrating optical systems in additive manufacturing processes, such as powder bed fusion, are complex and require accurate alignment with the global machine coordinate system, making them time-consuming and operator skill-dependent, especially when monitoring melt pools during three-dimensional work piece production.
Innovation Solution
A method and device that generate a calibration spot within the scanner coordinate system, allowing for the emission of a calibration beam to align the optical system's beam path with the radiation beam, enabling calibration independent of the global coordinate system and scan field corrections, using a target and adjustment device to align optical components manually or automatically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing calibration methods are used that require accurate alignment with the global machine coordinate system, then measurement precision is improved, but device complexity and operator skill dependency increase
Solution Approach 1:
The patent introduces a calibration object with a known geometric structure (such as a calibration grid or patterned target) as an intermediary between the optical system and the global coordinate system. This calibration object serves as a mediator that establishes the relationship between the scanner coordinate system and the global machine coordinate system through feature detection and geometric transformation, eliminating the need for complex direct alignment procedures.
Solution Approach 2:
The patent creates a digital model or coordinate transformation map that copies the spatial relationships from the physical calibration object into the scanner coordinate system. By detecting known features on the calibration object and establishing their coordinates in the scanner system, the method creates a reference framework that enables accurate coordinate transformation without requiring manual alignment with the global coordinate system.
2Measurement precision
If existing calibration methods requiring global coordinate system alignment are used, then measurement precision is improved, but calibration time increases
Solution Approach 1:
The patent performs preliminary calibration by detecting features on the calibration object and establishing the coordinate transformation relationship between the scanner coordinate system and global coordinate system before actual measurement or production begins. This preliminary setup creates a reusable reference framework that eliminates the need for time-consuming alignment procedures during subsequent operations.
Solution Approach 2:
The patent creates a digital coordinate transformation model that copies the spatial relationships from the physical calibration object into the scanner coordinate system. Once this digital model is established through feature detection, it can be reused for multiple measurements and production cycles, significantly reducing calibration time while maintaining precision.
3Measurement precision
If manual alignment procedures are used for calibration, then measurement precision can be achieved, but operator skill dependency increases
Solution Approach 1:
The patent enables the calibration system to perform self-alignment by automatically detecting features on the calibration object and computing the coordinate transformation relationship. The system uses image processing and geometric algorithms to identify known patterns on the calibration target and establish the scanner coordinate system's orientation and position relative to the global coordinate system without requiring manual intervention or operator expertise in alignment procedures.
Solution Approach 2:
The patent replaces manual mechanical alignment procedures with automated optical and computational methods. Instead of requiring operators to physically adjust and align components based on visual cues or measurement tools, the system uses camera-based detection of calibration object features and computational geometry to automatically establish coordinate relationships, eliminating the need for operator skill in manual alignment.
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 and accelerates the calibration process, ensuring reliable alignment of optical systems without requiring precise positioning in the global machine coordinate system, thus improving operational efficiency and reducing operator dependency.
Implementation Method 1
generating a calibration spot by irradiating a target with a radiation beam emitted by an optical unit
Implementation Method 2
an optical system which in particular forms an inline system with the radiation beam, i.e. which transmits or receives radiation in the radiation beam's beam path
Data Source
AI summary
A method for calibrating an optical system (24), in particular for use in an apparatus (100) for producing a three-dimensional work piece by irradiating layers of a raw material powder is described. The method comprises the step i) generating a calibration spot (C) by irradiating a target (32) with a radiation beam (14) emitted by an optical unit (16) at a known position within a scanner coordinate system of a scanner (22) configured to scan the radiation beam (14) across an irradiation plane (I). In a step ii), a calibration beam (36) is emitted from the calibration spot (C) in a direction of the optical system (24) to be calibrated. In a step iii), the optical system (24) is calibrated such that a beam path of the calibration beam (36) emitted from the calibration spot (C) is collinear with a beam path of the radiation beam (14) used in step i) for generating the calibration spot (C).