Phase Modulator Using Hybrid Aligned Nematic Liquid Crystal
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Solution Overview
Problem
Conventional liquid crystal (LC) modes struggle to achieve a 180-degree rotation of LC molecules necessary for phase modulation of circular polarized light, requiring complex and costly manufacturing processes or unsuitable for phase modulation due to alternating rotation directions within a pixel.
Innovation Solution
A phase modulator using a hybrid aligned nematic (HAN) arrangement with substrates having different surface orientations for LC alignment, allowing controlled in-plane rotation of LC molecules over 180 degrees via electric field, achieving phase modulation from 0 to 2π with a λ/2 plate-like optical function, and optionally using a circular polarizer for reduced thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional LC modes (nematic or smectic) are used, then the device structure is simple, but the angular range of LC molecule rotation is limited to 90 degrees maximum
Solution Approach 1:
The patent combines two different LC modes (nematic and smectic) in a single device structure. The nematic LC layer provides in-plane rotation capability while the smectic LC layer provides out-of-plane rotation capability, merging their advantages to achieve a full 180-degree angular range without increasing overall device complexity
Solution Approach 2:
The invention transitions from single-dimension rotation control to two-dimension rotation control by stacking LC layers with different alignment characteristics. The first LC layer rotates molecules in the plane of the substrate while the second LC layer rotates molecules perpendicular to the substrate surface, enabling comprehensive angular control
2Adaptability or versatility
If switchable surface alignment is combined with LC modes to enlarge angular range, then the angular range increases, but manufacturing and control processes become more elaborate and costly
Solution Approach 1:
The patent applies different surface alignment characteristics to different regions of the device. The first substrate has in-plane alignment while the second substrate has out-of-plane alignment, creating local quality differences that enable 180-degree rotation without requiring complex switchable alignment layers throughout the entire device
Solution Approach 2:
The invention changes the alignment parameter of the LC molecules by using substrates with different surface treatments. By fixing the alignment state of the two substrates in opposite configurations, the system achieves enlarged angular range through parameter differentiation rather than complex dynamic control
3Ease of manufacture
If hybrid aligned nematic LC mode is used, then manufacturing with standard procedures is possible, but alternating rotation directions within a pixel occur
Solution Approach 1:
The patent segments the LC layer into two distinct functional layers: a nematic LC layer for in-plane rotation and a smectic LC layer for out-of-plane rotation. This segmentation allows each layer to perform its specific rotation function independently, preventing alternating rotation directions within the same pixel while maintaining ease of manufacture
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
Enables efficient and cost-effective phase modulation of circular polarized light with simpler manufacturing and control compared to prior solutions, suitable for both transmissive and reflective displays, and applicable in holographic and stereoscopic imaging.
Implementation Method 1
the long axis of the LC molecules is turned, for example as induced by the application of an electric field
Implementation Method 2
the phase of light can be modulated in that circular polarised light is used
Implementation Method 3
a λ/2 plate is rotated in its plane... the phase at the exit will change by the angle 2φ
Data Source
AI summary
A phase modulator for the modulation of the phase of circular polarised light which interacts with the phase modulator. The phase modulator has a first and a second substrate, an electrode arrangement and a liquid crystal layer with liquid crystal molecules. The first substrate is disposed adjacent to the second substrate. The liquid crystal layer is disposed between the two substrates. The first substrate has a first surface, and the second substrate has a second surface. The liquid crystal molecules situated next to the first surface are oriented substantially parallel to the first surface. The liquid crystal molecules situated next to the second surface are oriented substantially perpendicular to the second surface. An in-plane component of the liquid crystal molecule orientation can be set within an angular range of about 180°, e.g. between −90° and +90° related to a specifiable central orientation.