Optical Master Patterning of Liquid Crystal Layers for Large-Area GPHs
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Solution Overview
Problem
Existing methods for forming geometric phase holograms (GPHs) with liquid crystal layers require complex and highly constrained systems, leading to low throughput and manufacturing challenges, especially when patterning over large areas.
Innovation Solution
Utilize optical masters with surface relief features to align liquid crystal molecules, which are then polymerized to maintain their orientation, and use diffraction of light through these masters to pattern a photo-alignment layer, allowing for high precision and high throughput replication of GPHs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If soft-imprint alignment processes with reusable alignment templates are used to pattern liquid crystal polymer layers, then manufacturing precision and reliability are improved, but device complexity and manufacturing time increase due to multiple sequential steps
Solution Approach 1:
The patent combines the alignment template and master pattern into a single integrated optical master structure. The master contains both the surface relief features for alignment and the pattern transfer capability, eliminating the need for separate alignment templates and reducing the number of sequential steps in the patterning process.
Solution Approach 2:
The optical master is pre-formed with the desired pattern and surface relief features before the liquid crystal layer is applied. This preliminary preparation allows the liquid crystal molecules to self-align during a single exposure step, rather than requiring sequential alignment and patterning operations.
2Reliability
If conventional methods for forming geometric phase holograms are used, then liquid crystal patterns can be formed, but throughput is reduced and manufacturing constraints are increased due to complex system requirements
Solution Approach 1:
The patent replaces complex mechanical alignment systems with an optical field-based approach. Light diffraction through the master's surface relief features directly patterns the photo-alignment layer, eliminating the need for precise mechanical positioning and complex constraint systems during manufacturing.
Solution Approach 2:
The optical master serves as a reusable copy that can be used to replicate the desired pattern multiple times. The master contains the complete pattern information that is copied onto each liquid crystal layer through optical exposure, enabling high-volume production without requiring complex real-time control systems.
3Manufacturing precision
If optical masters with surface relief features are used to align and polymerize liquid crystal molecules, then manufacturing precision is improved, but the process time increases due to additional polymerization steps
Solution Approach 1:
The patent uses photo-polymerization to change the chemical state of the liquid crystal layer, transforming it from a reconfigurable state to a fixed pattern state. This parameter change allows the pattern to be locked in with high precision while maintaining a relatively short process time through efficient UV curing.
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
Facilitates the formation of GPHs with relaxed manufacturing constraints and high throughput by using easily created optical masters that can replicate large areas with precise alignment and patterning of liquid crystal molecules.
Implementation Method 1
use diffraction of light through these masters to pattern a photo-alignment layer
Implementation Method 2
the liquid crystal molecules of the liquid crystal polymer are aligned to the surface alignment pattern via chemical, steric, or other intermolecular interaction
Implementation Method 3
which are then polymerized to maintain their orientation
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
In some implementations, an optical master is created by using a nanoimprint alignment layer to pattern a liquid crystal layer. The nanoimprint alignment layer and the liquid crystal layer constitute the optical master. The optical master is positioned above a photo-alignment layer. The optical master is illuminated and light propagating through the nanoimprinted alignment layer and the liquid crystal layer is diffracted and subsequently strikes the photo-alignment layer. The incident diffracted light causes the pattern in the liquid crystal layer to be transferred to the photo-alignment layer. A second liquid crystal layer is deposited onto the patterned photo-alignment layer, which subsequently is used to align the molecules of the second liquid crystal layer. In some implementations, the second liquid crystal layer in the patterned photo-alignment layer may be utilized as a replica optical master or as a diffractive optical element, such as for directing light in optical devices such as display devices, including augmented reality display devices.