Optical Element Alignment Using Fewer Masks for High Diffraction Efficiency
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Solution Overview
Problem
Existing methods for producing Pancharatnam-Berry phase optical elements (PBOE) face challenges in achieving high diffraction efficiency due to discrete molecular alignment patterns resulting from multiple masks, leading to increased production costs and complexity.
Innovation Solution
An optical element with an optically anisotropic layer containing anisotropic molecules arranged in a continuous, periodic pattern through a method involving multiple exposures with differently polarized UV lights, using a mask set with overlapping light-transmitting portions to achieve molecular alignments without increasing the number of masks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple masks are used to achieve continuous molecular alignment pattern, then diffraction efficiency is improved, but device complexity and production cost increase
Solution Approach 1:
The patent divides the alignment film into multiple exposure regions, where each region is exposed to UV light with a specific polarization axis angle. This segmentation allows different molecular alignment directions to be formed in different regions using a single mask, achieving continuous periodic alignment without requiring multiple masks. Each exposure region corresponds to a segment of the periodic pattern, and the combination of these segments forms the complete continuous pattern.
Solution Approach 2:
The patent applies different polarization axis angles of UV light to different exposure regions of the alignment film. Each region receives UV light with a specific polarization angle that determines the molecular alignment direction in that region. This local differentiation of polarization angles enables the formation of continuous periodic molecular alignment patterns with varying orientation angles (e.g., 0°, 45°, 90°, 135°) across the film, achieving high diffraction efficiency without increasing mask complexity.
2Manufacturing precision
If multiple masks are used to achieve continuous molecular alignment pattern, then diffraction efficiency is improved, but production cost increases
Solution Approach 1:
The patent segments the alignment film into multiple exposure regions that can be processed simultaneously with a single mask. By dividing the film area into regions that receive UV light with different polarization angles, the patent achieves the molecular alignment pattern that would otherwise require multiple masks. This segmentation strategy reduces the number of mask fabrication and handling steps, thereby lowering production costs while maintaining continuous periodic alignment.
Solution Approach 2:
The patent implements local quality by applying different polarization axis angles to different regions of the alignment film during a single exposure process. This allows the formation of multiple molecular alignment directions (e.g., 0°, 45°, 90°, 135°) across the film using one mask, eliminating the need for multiple separate mask fabrication and alignment steps. The reduction in process steps directly decreases production costs while achieving the required continuous periodic alignment for high diffraction efficiency.
3Manufacturing precision
If multiple masks are used to achieve continuous molecular alignment pattern, then diffraction efficiency is improved, but production steps increase
Solution Approach 1:
The patent segments the alignment film into multiple exposure regions that can be processed in parallel during a single exposure step. Each region is exposed to UV light with a specific polarization angle, and all regions are processed simultaneously in one operation. This segmentation allows the formation of continuous periodic molecular alignment patterns with multiple orientation angles (e.g., 0°, 45°, 90°, 135°) in a single exposure step, eliminating the need for multiple sequential exposure steps with different masks, thereby improving productivity.
Solution Approach 2:
The patent applies local quality by using a single mask to expose different regions of the alignment film to UV light with different polarization angles simultaneously. This local differentiation of polarization angles across the film enables the formation of multiple molecular alignment directions in one exposure step, reducing the total number of production steps from multiple sequential mask exposures to a single combined exposure process. This reduction in production steps directly improves productivity while maintaining continuous periodic alignment.
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 proposed method enables high diffraction efficiency with a simpler production process, reducing costs and complexity by aligning anisotropic molecules in a continuous, periodic pattern using fewer masks.
Implementation Method 1
an exposure step of exposing an alignment film on a supporting substrate to light for alignment treatment
Implementation Method 2
It is important for a PBOE to have a periodic, continuous molecular alignment pattern in the plane to achieve a high diffraction efficiency
Data Source
AI summary
Provided are an optical element that has a high diffraction efficiency and can be produced through a simple procedure, a method of producing the optical element, and a mask set for use in production of the optical element. The optical element of the present invention includes an optically anisotropic layer containing anisotropic molecules. The optically anisotropic layer includes a first region that is a region where the anisotropic molecules are not twist-aligned in a film thickness direction of the optically anisotropic layer, and a second region that is a region where the anisotropic molecules are twist-aligned in the film thickness direction of the optically anisotropic layer.