Optical Modulator with Retardation Device for Uniform Photopolymerization
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Solution Overview
Problem
Existing methods for forming three-dimensional objects using photocurable resin with liquid crystal shutters result in uneven density and warping due to the relationship between linearly polarized light and resin flow, leading to reduced light utilization efficiency.
Innovation Solution
An optical forming device that includes a light source and an optical modulator with a liquid crystal device and an optical retardation device to modulate and impart a phase difference to the light, ensuring uniform curing of the resin independent of resin flow direction, thereby preventing unevenness and enhancing light utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If linearly polarized light from a liquid crystal shutter is used to cure photocurable resin, then the resin can be selectively cured in a pattern, but uneven density and warping occur due to the relationship between light polarization and resin flow direction
Solution Approach 1:
The patent changes the polarization state parameter of the light from linear polarization to circular polarization by introducing a quarter-wave plate. This parameter change ensures that the light interacts uniformly with the resin regardless of flow direction, eliminating density unevenness while maintaining patterned curing capability.
Solution Approach 2:
The quarter-wave plate serves as an intermediary optical element between the liquid crystal shutter and the photocurable resin. It transforms the linearly polarized light into circularly polarized light, mediating the interaction between light and resin to prevent density variations caused by directional sensitivity.
2Manufacturing precision
If linearly polarized light is used to irradiate photocurable resin, then patterned curing can be achieved, but light utilization efficiency decreases
Solution Approach 1:
The patent changes the polarization state from linear to circular, which optimizes the interaction between light and the polymerization initiator in the resin. This parameter change improves light absorption efficiency and reduces energy loss while preserving the ability to achieve patterned curing through the liquid crystal shutter modulation.
3Productivity
If the cured photocurable resin is moved after each layer curing, then layer-by-layer three-dimensional object formation is enabled, but density unevenness and warping occur
Solution Approach 1:
The patent modifies the light polarization parameter to circular polarization, which eliminates the directional sensitivity that causes density unevenness during resin flow and curing. This allows the layer-by-layer formation process to proceed without compromising density uniformity, even as resin is moved between layers.
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
The solution effectively prevents uneven density and warping in the cured resin, achieving high light utilization efficiency and uniform curing of the three-dimensional object.
Implementation Method 1
an optical retardation device to impart a phase difference to the linearly polarized light emitted from the liquid crystal device, and emit the light imparted with the phase difference
Implementation Method 2
an optical modulator to modulate the light for causing the liquid photocurable resin to undergo curing in a pattern based on a shape of a three-dimensional object
Implementation Method 3
the optical modulator includes a liquid crystal device to modulate the light for causing the liquid photocurable resin to undergo curing in the pattern, and emit the modulated light as linearly polarized light
Implementation Method 4
polymerization initiator included in photocurable resin most effectively absorbs linearly polarized light when the vibration direction of the incident linearly polarized light (polarization direction) is parallel with the transition moment of the polymerization initiator, thereby initiating polymerization of monomers, oligomers, and the like included in the photocurable resin
Data Source
AI summary
An optical forming device includes a light source to emit light for causing liquid photocurable resin to undergo curing and an optical modulator to modulate the light for causing the liquid photocurable resin to undergo curing in a pattern based on a shape of a three-dimensional object, and irradiate the liquid photocurable resin with the modulated light. The optical modulator includes a liquid crystal device to modulate the light for causing the liquid photocurable resin to undergo curing in the pattern, and emit the modulated light as linearly polarized light and an optical retardation device to impart a phase difference to the linearly polarized light emitted from the liquid crystal device, and emit the light imparted with the phase difference.