Geometric Phase Optical Element for Large-Angle Light Deflection
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Solution Overview
Problem
Existing optical elements, such as lenses and deflectors, lack the ability to provide large deflection angles and high efficiency while maintaining a thin form factor, and existing light deflection devices are limited in size reduction and weight optimization.
Innovation Solution
A geometric phase optical element utilizing a liquid crystal layer with adjustable phase differences and transparent electrodes, allowing for varying deflection angles and focal distances through applied voltages, enabling a simple structure with enhanced deflective efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a general optical lens is used, then the structure is simple, but the deflection angle is limited and the response rate is low
Solution Approach 1:
The patent changes the physical parameters of the optical element by using liquid crystal materials with adjustable refractive indices and incorporating geometric phase patterns (Pancharatnam-Berry phase) to achieve high response rates and large deflection angles while maintaining a thin structure. The liquid crystal molecules can be reoriented by applied voltages to rapidly change the phase distribution and deflect light angles.
2Device complexity
If a general optical deflector is used, then the structure is conventional, but the deflective angle is small and efficiency is reduced
Solution Approach 1:
The patent introduces a new dimension of control by using the geometric phase (Pancharatnam-Berry phase) which depends on the orientation of liquid crystal molecules rather than just the path length. This allows for much larger effective phase delays (up to 4π) and consequently larger deflection angles without increasing the physical thickness of the device.
Solution Approach 2:
The patent uses composite structures combining liquid crystal materials with specific geometric patterns (gratings, lenses) to achieve both the phase modulation capability and the light deflection function in a single thin element, improving efficiency while maintaining simplicity.
3Length of moving object
If the optical element is made thin, then the form factor is optimized, but the manufacturing precision requirements increase
Solution Approach 1:
The liquid crystal material itself provides the phase modulation function without requiring precise mechanical fabrication of the phase pattern. The geometric phase pattern is formed by controlling the molecular orientation of the liquid crystal, which can be achieved through standard liquid crystal alignment techniques rather than high-precision mechanical manufacturing.
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 geometric phase optical element achieves greater deflection angles and focal distances with increased efficiency, suitable for large area displays and three-dimensional imaging applications.
Implementation Method 1
a geometric phase optical element may operate as a lens or a deflector via a phase difference of a liquid crystal
Implementation Method 2
The geometric phase optical element, compared with a general optical lens, has a greater change in a diopter
Implementation Method 3
a diffraction element in which a periodic structure pitch gradually changes from a center of deflection from the light deflection element toward an outside
Data Source
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AI summary
A geometric phase optical element and a three-dimensional display apparatus including the same are provided. The geometric phase optical element includes: a liquid crystal layer; a first electrode on a surface of the liquid crystal layer; and a second electrode on another surface of the liquid crystal layer, wherein, when no voltage is applied to the first and second electrodes, the liquid crystal layer is configured such that a phase difference according to an arrangement of the liquid crystal is π and light transmitted through the liquid crystal layer is diffracted by a first deflection angle, and when a first voltage that causes the phase difference according to the arrangement of the liquid crystal to become π/2 is applied to the first and second electrodes, the liquid crystal layer is configured such that the light transmitted through the liquid crystal layer is diffracted by a second deflection angle.