Optical Control Device for Additive Manufacturing Focus Drift
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Solution Overview
Problem
In additive manufacturing, particularly for metal objects, accurately and reproducibly solidifying selective parts of layers is challenging due to focus drift caused by thermo-mechanical and thermo-optical behavior of optical components, leading to variations in product quality.
Innovation Solution
An apparatus with an optical control device featuring a focus unit, sensor element, and focus correction lens element, along with a focus correction control unit, is used to actively compensate for focus drift by adjusting the focus of electromagnetic radiation on the surface level of the material, ensuring accurate and reproducible solidification of layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If electromagnetic radiation is used to solidify material layers in additive manufacturing, then manufacturing speed and flexibility are improved, but focus drift occurs due to thermo-mechanical and thermo-optical behavior of optical components, worsening manufacturing precision
Solution Approach 1:
A sensor element detects the actual focus position of the electromagnetic radiation on the material surface, and this detection signal is fed back to a control unit. The control unit compares the detected focus position with the desired focus position and adjusts the focus correction lens element accordingly to maintain accurate focus, thereby resolving the focus drift problem while maintaining high manufacturing speed
Solution Approach 2:
The patent introduces a focus correction lens element that can change its position or focal parameters in real-time based on thermal conditions and detected focus drift. By dynamically adjusting optical parameters (lens position, focal length) in response to thermal-mechanical and thermal-optical effects, the system maintains manufacturing precision despite the high-speed electromagnetic radiation solidification process
2Manufacturing precision
If optical components are used to focus electromagnetic radiation on material, then selective solidification capability is improved, but thermo-mechanical and thermo-optical behavior of these components causes focus drift, worsening reliability
Solution Approach 1:
The sensor element continuously monitors the focus position and provides real-time feedback to the control unit. This closed-loop feedback system detects and compensates for focus drift caused by thermal-mechanical and thermal-optical effects in the optical components, ensuring reliable and stable focus positioning throughout the manufacturing process
Solution Approach 2:
A focus correction lens element is introduced as an intermediary optical component between the main focusing system and the material surface. This intermediate lens serves as a compensating element that can adjust the overall focus position to counteract drift caused by other optical components, thereby improving focus stability and reliability
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 solution enables precise control over the focus of electromagnetic radiation, effectively mitigating focus drift and improving the accuracy and reproducibility of solidified parts, thereby enhancing product quality.
Implementation Method 1
a sensor element arranged for detecting a measure for the accuracy of the focus of the electromagnetic radiation
Implementation Method 2
The focus correction lens element is arranged to be movable in the direction of at least an optical axis thereof. Hence, the overall focus of the electromagnetic radiation on the focal plane may be changed or adjusted by moving the focus correction lens element
Implementation Method 3
a solidifying device for solidifying a selective layer-part of the material on the surface level by means of electromagnetic radiation
Data Source
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AI summary
The invention relates to an apparatus for producing an object by means of additive manufacturing, comprising a process chamber for receiving a bath of material which can be solidified by exposure to electromagnetic radiation; a support for positioning the object in relation to the surface level of the bath of material; and a solidifying device for solidifying a selective layer-part of the material on the surface level by means of electromagnetic radiation. Furthermore optical control device is provided with a focus unit in an optical pathway of the electromagnetic radiation of the solidifying device, and arranged for controlling at least the focus of the electromagnetic radiation emitted by the solidifying device on the surface level. According to the invention, the optical control device comprises a sensor element arranged for detecting a measure for the accuracy of the focus of the electromagnetic radiation and a focus correction lens element that is arranged to be movable. By moving said focus correction lens element, focus may be corrected, for example due to thermal behaviour of the optical system.