Transmissive liquid crystal diffraction element
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Solution Overview
Problem
Existing liquid crystal diffraction elements cannot diffract different polarized light components in the same direction, leading to inefficiencies in light control.
Innovation Solution
A transmissive liquid crystal diffraction element comprising a first and second optically-anisotropic layer with opposite rotation directions of optical axes, where the layers have the same single period and twisted angles less than 360°, allowing for the alignment of rod-like or disk-like liquid crystal compounds, and optionally including a retardation layer and λ/4 plate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single liquid crystal layer with uniform twist direction is used, then the structure is simple, but different polarized light components cannot be diffracted in the same direction
Solution Approach 1:
The liquid crystal diffraction element is divided into multiple liquid crystal layers, each with different twist directions. This segmentation allows each layer to handle different polarized light components, enabling both left and right circularly polarized light to be diffracted in the same direction while maintaining overall functional simplicity
Solution Approach 2:
The multi-layer structure with opposite twist directions creates a universal diffraction element that can process both left and right circularly polarized light simultaneously. Each layer contributes to the overall function of diffracting different polarized light components in the same direction, achieving multi-functionality within a unified device
2Strength
If the liquid crystal compound is twisted and aligned in the thickness direction with a twisted angle of 360° or more, then the optical anisotropy is enhanced, but the diffraction efficiency for different polarized light components decreases
Solution Approach 1:
The patent optimizes the twisted angle to be less than 360° to achieve a dynamic balance between optical anisotropy and diffraction efficiency. This intermediate angle allows sufficient optical anisotropy for effective light bending while maintaining high diffraction efficiency for different polarized light components
Solution Approach 2:
The twisted angle parameter is specifically controlled to be less than 360° rather than using maximum values. This parameter optimization ensures that the liquid crystal layers provide adequate optical anisotropy for light control while avoiding excessive twisting that would reduce diffraction efficiency
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 the diffraction of right and left circularly polarized light in the same direction with high efficiency, enhancing light control capabilities.
Implementation Method 1
a transmissive liquid crystal diffraction element that diffracts incident light
Implementation Method 2
a first optically-anisotropic layer and a second optically-anisotropic layer each of which has a liquid crystal alignment pattern in which a direction of an optical axis derived from a liquid crystal compound changes while continuously rotating
Implementation Method 3
the liquid crystal compound in each of the first optically-anisotropic layer and the second optically-anisotropic layer is twisted and aligned in a thickness direction
Implementation Method 4
a direction of an optical axis derived from a liquid crystal compound changes while continuously rotating in at least one in-plane direction
Data Source
AI summary
A transmissive liquid crystal diffraction element includes a first optically-anisotropic layer and a second optically-anisotropic layer each of which has a liquid crystal alignment pattern in which a direction of an optical axis derived from a liquid crystal compound changes while continuously rotating in at least one in-plane direction, in which a rotation direction of the optical axis in the liquid crystal alignment pattern of the first optically-anisotropic layer and a rotation direction of the optical axis in the liquid crystal alignment pattern of the second optically-anisotropic layer are opposite to each other, and a single period of the liquid crystal alignment pattern in the first optically-anisotropic layer and a single period of the liquid crystal alignment pattern in the second optically-anisotropic layer are the same.