Pancharatnam-Berry Phase Optical Element Azimuth Domain Design
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Solution Overview
Problem
Pancharatnam-Berry phase optical elements with multiple focal lengths face challenges in achieving favorable optical characteristics due to disclinations (liquid crystal misalignments) at the boundaries of alignment domains.
Innovation Solution
A Pancharatnam-Berry phase optical element is designed with a photoalignment film and a liquid crystal layer featuring alignment domains with reference alignment azimuths that differ by less than 90 degrees, including first and second alignment domains arranged in specific configurations to minimize disclinations, and a method involving photoalignment treatment with polarized lights to define these domains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple alignment domains with different reference alignment azimuths are introduced in a PBOE to achieve variable focal length, then the optical functionality is improved, but disclinations occur at the boundaries of alignment domains degrading optical characteristics
Solution Approach 1:
The patent applies local quality by creating different alignment domains with specific reference alignment azimuths (0°, 45°, 90°, 135°) in different regions of the liquid crystal layer. Each domain has locally optimized alignment characteristics that contribute to the overall variable focal length functionality while minimizing disclination effects through careful azimuth selection.
Solution Approach 2:
The patent utilizes asymmetry by introducing alignment domains with non-uniform reference alignment azimuths throughout the liquid crystal layer. The asymmetric arrangement of domains with different azimuths (0°, 45°, 90°, 135°) creates the necessary optical anisotropy for variable focal length operation while managing the trade-off with disclination-induced optical degradation.
2Power
If alignment domains with large difference in reference alignment azimuth are used, then the Pancharatnam-Berry phase modulation is enhanced, but disclinations increase at domain boundaries
Solution Approach 1:
The patent applies parameter changes by systematically varying the reference alignment azimuth parameter across different domains (0°, 45°, 90°, 135°). This parameter variation enables strong Pancharatnam-Berry phase modulation while controlling the azimuth differences to manageable levels that reduce disclination formation and maintain alignment uniformity.
3Ease of manufacture
If conventional photoalignment treatment is used, then the alignment domains can be formed, but disclinations occur at boundaries making production of high-quality optical elements difficult
Solution Approach 1:
The patent applies preliminary action by performing photoalignment treatment to create the alignment domains with specific reference alignment azimuths before assembling the complete optical element. This preliminary formation of domains with controlled azimuths (0°, 45°, 90°, 135°) enables subsequent optimization of the liquid crystal layer properties to minimize disclinations and achieve high optical characteristics.
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 solution effectively reduces or eliminates disclinations, resulting in a Pancharatnam-Berry phase optical element with improved optical characteristics and suitable for production, enhancing diffraction efficiency and reducing haze.
Implementation Method 1
a photoalignment film; and a liquid crystal layer in contact with the photoalignment film, the liquid crystal layer including alignment domains with reference alignment azimuths of liquid crystal molecules defined by the photoalignment film
Implementation Method 2
Pancharatnam-Berry phase optical element including: a photoalignment film; and a liquid crystal layer in contact with the photoalignment film, the liquid crystal layer including alignment domains with reference alignment azimuths of liquid crystal molecules defined by the photoalignment film
Data Source
AI summary
Provided are a Pancharatnam-Berry phase optical element with less or no occurrence of disclinations and with excellent optical characteristics, and a method of producing a Pancharatnam-Berry phase optical element which is suitable for production of the Pancharatnam-Berry phase optical element above. The Pancharatnam-Berry phase optical element includes: a photoalignment film; and a liquid crystal layer in contact with the photoalignment film. The liquid crystal layer includes alignment domains with reference alignment azimuths of liquid crystal molecules defined by the photoalignment film, the reference alignment azimuths being different from one another. The alignment domains include first alignment domains and second alignment domains, with each of the second alignment domains being positioned between two of the first alignment domains and in contact with each of the two first alignment domains. A difference in reference alignment azimuth between the first alignment domains is not 90°.