Variable-Focal-Volume Lithography for 3D Resolution and Throughput
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Solution Overview
Problem
Existing lithography-based generative production methods face challenges in achieving high throughput without compromising high structural resolution, particularly due to issues with material adherence, refraction index mismatch, and long build times, especially when producing large components with fine structures.
Innovation Solution
The method involves varying the focal point volume during the build process to create solidified volume elements of different sizes, using optical elements to adjust the focal point volume without changing radiation intensity, allowing for high resolution in small focal points and increased throughput with larger focal points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If exposure from above is used with very thin layers of photosensitive material to obtain good surfaces, then surface quality is improved, but material application difficulty increases significantly
Solution Approach 1:
The patent inverts the conventional exposure direction by introducing radiation from below through the tank bottom rather than from above. This allows the use of thicker material layers (avoiding application difficulties) while maintaining good surface quality through controlled solidification from the bottom, effectively resolving the contradiction between surface quality and material application ease.
2Quantity of substance
If exposure from below is used with upwardly moved construction platform, then material quantities are reduced, but component adherence to tank increases causing high extraction forces
Solution Approach 1:
The patent introduces an inhibition layer (mediator) between the tank bottom and the component by introducing oxygen. This layer prevents direct adherence between the component and tank while allowing the component to be supported during building, thereby reducing extraction forces when removing the component from the tank.
3Quantity of substance
If continuous flow of photosensitive material is used in thin gap, then material supply is maintained, but flow control becomes problematic with thicker-walled components or highly viscous materials
Solution Approach 1:
The patent dynamically adjusts the gap thickness between the tank bottom and construction platform during the building process. The gap is made larger during material supply phases to facilitate flow, then reduced when solidification is needed, allowing continuous material supply while maintaining control over the process for various material viscosities and component wall thicknesses.
4Manufacturing precision
If high resolution is required for fine structures, then build time increases rapidly
Solution Approach 1:
The patent segments the solidification process into two stages: first, rapid solidification of the entire component volume using large focal point volumes for low-resolution initial structures; second, selective re-solidification of surface layers using small focal point volumes for high-resolution finishing. This segmentation allows high resolution where needed while maintaining overall build time efficiency.
Solution Approach 2:
The patent applies different focal point volumes (and thus different resolution levels) to different regions and stages of the component building process. Large focal points are used for bulk material solidification, while small focal points are used for surface layer refinement, achieving local optimization between resolution and build time.
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 enables high-resolution structures with improved throughput by optimizing focal point volumes for both fine and coarse structures, reducing build times and minimizing material adherence, thus enhancing industrial applicability.
Implementation Method 1
the solidification is effected by multiphoton absorption
Data Source
AI summary
In a method for lithography-based generative production of three-dimensional components, in which material that can be solidified under the effect of electromagnetic radiation is arranged in a vat, a build platform is positioned at a distance from the vat bottom, material located between the build platform and the vat bottom is irradiated at selected locations with the aid of an irradiating unit, the electromagnetic radiation is introduced into the material from below through a vat bottom that is transmissive to the radiation, at least in a certain region, and successively focused on focal points within the material, whereby a volume element of the material that is respectively located at the focal point is solidified. The solidification takes place by means of multiphoton absorption and the volume of the focal point is varied at least once during the method, and so the component is built up from solidified volume elements of different volumes.