Variable-Focus Laser Optics for Adaptive Additive Fabrication
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Solution Overview
Problem
Laser-based additive fabrication systems are limited by fixed spot sizes, require complex optical components for beam direction, and suffer from optical aberrations, which hinder efficient formation of varying feature sizes and can lead to longer processing times and mechanical calibration issues.
Innovation Solution
The use of a variable focus lens and VCSEL arrays, along with flexible display films, allows for adjustable spot sizes and shapes of the light beam, enabling more efficient curing of photopolymers and powders by varying the focal length and power density, and eliminating the need for precise optical component calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If laser-based additive fabrication systems use fixed spot sizes, then the system structure is simple, but the manufacturing precision and adaptability are limited for varying feature sizes
Solution Approach 1:
The patent applies dynamics by making the focal length of the lens adjustable rather than fixed. The lens focal length can be dynamically changed to vary the spot size of the cured area, allowing the system to adapt to different feature size requirements. This resolves the contradiction by enabling manufacturing precision for varying features without requiring multiple fixed optical components.
Solution Approach 2:
The patent changes the parameter of focal length to control spot size. By adjusting the focal length parameter of the lens, the system can vary the curvature of the cured surface and the size of the treatment spot. This allows precise control over feature sizes while using a single adjustable lens instead of multiple fixed optical components.
2Adaptability or versatility
If complex optical components are used for beam direction, then the adaptability is improved, but the device complexity and mechanical calibration requirements increase
Solution Approach 1:
The patent replaces mechanical beam direction systems (such as galvanometer mirrors or moving stages) with a spatial light modulator or digitally controlled lens array. This allows electronic control of beam direction and focal point without mechanical moving parts, reducing calibration requirements while maintaining adaptability to direct energy to selected portions.
Solution Approach 2:
The patent uses a single lens or spatial light modulator that can simultaneously perform multiple functions: directing the beam to different locations, adjusting focal length, and controlling spot size. This multi-functional component replaces what would traditionally require multiple specialized optical components, reducing overall system complexity.
3Productivity
If fixed focal length lenses are used, then the device complexity is reduced, but the productivity decreases due to longer processing times for varying feature sizes
Solution Approach 1:
The patent implements a dynamically adjustable lens system where the focal length can be changed rapidly without mechanical repositioning. This allows the system to quickly adapt between small and large feature sizes, improving productivity by eliminating the need to use a fixed small spot size for all features which would require excessive scanning time.
Solution Approach 2:
The patent changes the focal length parameter on-demand based on the feature size being fabricated. For large features, a longer focal length is used to create larger spots and reduce the number of scan positions required. For small features, a shorter focal length provides the necessary precision. This dynamic parameter adjustment significantly improves layer formation speed.
4Manufacturing precision
If optical components require precise calibration, then the manufacturing precision is improved, but the ease of operation and maintenance difficulty increase
Solution Approach 1:
The patent replaces mechanical calibration systems with digitally controlled optical elements. The spatial light modulator or adjustable lens array is controlled by digital signals that can be precisely programmed and reproduced, eliminating the need for manual mechanical calibration. This maintains manufacturing precision through digital control while dramatically improving ease of operation.
Solution Approach 2:
The patent implements self-calibration capabilities through digital reference systems and feedback control. The system can automatically reference known positions and adjust its digital control parameters to maintain precision without requiring external calibration equipment or expert intervention, making the system easier to operate and maintain.
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 faster and more precise formation of layers with varying feature sizes, reducing processing time and improving the accuracy of additive fabrication by allowing for adaptable spot sizes and shapes, while minimizing optical aberrations and mechanical calibration requirements.
Implementation Method 1
a flexible display film extended between the sides of the container, wherein the flexible display film is configured to emit radiation to cure selected portions of the liquid photopolymer in the container
Data Source
AI summary
According to some aspects, techniques that address one or more drawbacks of laser-based optical systems in additive fabrication devices are described. In some aspects, an additive fabrication device may include one or more variable focus lenses that may be operated (e.g., actuated) during fabrication to adjust the focus, and thereby the spot size, of a laser beam. In some aspects, an additive fabrication device may comprise a laser array, such as a plurality of vertical-cavity surface-emitting lasers (VCSELs), that may be operated to direct light into a build region, rather than using a single laser beam, such as a single diode laser. In some aspects, an additive fabrication device may comprise a container that includes a flexible display film, such as a flexible LCD screen, which may be operated to direct light into the container to thereby cure a liquid photopolymer therein.