Liquid Crystal Diffraction Element With Tilted Alignment for High Angles
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Solution Overview
Problem
Existing liquid crystal lenses face a challenge in achieving high diffraction efficiency when the single period of the liquid crystal alignment pattern is reduced, particularly in high diffraction angle regions, leading to insufficient performance.
Innovation Solution
A liquid crystal diffraction element with an optically-anisotropic layer featuring a liquid crystal alignment pattern where the tilt angle of the liquid crystal compound varies gradually and the single period changes, allowing the liquid crystal compound to have a tilt angle with respect to the surface of the optically-anisotropic layer, and regions with different tilt angles are present.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the single period of the liquid crystal alignment pattern is reduced to shorten the focal length and reduce optical system size, then the size and thickness of the optical system are reduced, but the diffraction efficiency is lowered particularly in high diffraction angle regions
Solution Approach 1:
The patent applies local quality by introducing a tilt angle variation region within the liquid crystal alignment pattern. Specifically, the liquid crystal molecules are oriented with a tilt angle relative to the substrate surface in a predetermined region, while maintaining the concentric circular alignment pattern. This localized modification of molecular orientation allows the system to achieve both compact size (through reduced single period) and high diffraction efficiency (through the tilt angle region that enhances light scattering and diffractive performance)
Solution Approach 2:
The patent changes the orientation parameter of the liquid crystal molecules by introducing a tilt angle component. Instead of having molecules aligned purely in the plane of the substrate (0° tilt), the molecules are oriented at a specific tilt angle (e.g., 45°) relative to the substrate surface in the tilt angle region. This parameter change enables the liquid crystal layer to maintain effective diffraction performance even when the single period is reduced, thereby resolving the contradiction between miniaturization and 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
This configuration maintains excellent diffraction efficiency even when the single period is reduced, enabling high light focusing efficiency and reduced size and thickness of the optical system.
Implementation Method 1
the optically-anisotropic layer has a liquid crystal alignment pattern in which an orientation of an optical axis derived from the liquid crystal compound changes while continuously rotating in at least one in-plane direction
Implementation Method 2
as the single period decreases, a diffraction angle of light increases
Implementation Method 3
on at least one surface of the optically-anisotropic layer, a region where the liquid crystal compound has a tilt angle with respect to the surface of the optically-anisotropic layer is provided
Data Source
AI summary
An object is to provide a liquid crystal diffraction element having excellent diffraction efficiency and an optical device including the liquid crystal diffraction element. The object is achieved by a liquid crystal diffraction element including an optically-anisotropic layer containing a liquid crystal compound, in which the optically-anisotropic layer has a liquid crystal alignment pattern in which an orientation of an optical axis derived from the liquid crystal compound changes while continuously rotating in at least one in-plane direction, a region where the liquid crystal compound has a tilt angle is provided, and a region where the tilt angle varies in a plane is provided.