Wire-grid polarizer asymmetric metal reflectors
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Solution Overview
Problem
Current wire-grid polarizers face challenges in achieving high polarization performance, maintaining required light transmittance, and reducing back-side reflectance, particularly in the visible light range, which is essential for applications like liquid crystal displays, projectors, and polarized sunglasses.
Innovation Solution
A wire-grid polarizer design where metal reflectors are embedded in grooves on a transparent sheet with a one-dimensional grid pattern, featuring specific thickness and width ratios, and a gradually thinner shape towards the tip, reducing back-side reflectance while maintaining high polarization performance and light transmittance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional wire-grid polarizers use uniform metal wire structures, then they achieve high polarization performance, but they exhibit high back-side reflectance which is undesirable for certain applications
Solution Approach 1:
The patent applies asymmetry by designing metal reflectors with non-uniform thickness - specifically, the reflectors have a first thickness in the central region and a second thickness (smaller than the first) in the end regions. This asymmetric thickness distribution allows the polarizer to maintain high polarization performance while reducing back-side reflectance, as the thinner end regions reduce the harmful reflective effects compared to uniform thickness structures
Solution Approach 2:
The patent applies local quality by varying the thickness of metal reflectors at different positions along their length. The central region maintains greater thickness for optimal polarization performance, while the end regions have reduced thickness to minimize back-side reflectance. This localized variation in reflector properties optimizes both polarization performance and reduces harmful reflections
2Ease of manufacture
If metal wire pitch is reduced to achieve high polarization performance in visible light range, then polarization degree improves, but manufacturing complexity increases significantly
Solution Approach 1:
The patent applies parameter changes by optimizing the pitch of metal reflectors to be in the range of 50-200 nm, which is specifically tailored for visible light wavelength ranges. This parameter optimization achieves high polarization degree (90% or more) while remaining compatible with available manufacturing techniques such as electron beam lithography and focused ion beam etching, thus balancing performance with manufacturing feasibility
3Ease of manufacture
If metal reflector thickness is increased to improve polarization performance, then polarization degree increases, but back-side reflectance increases which is harmful
Solution Approach 1:
The patent applies asymmetry by designing metal reflectors with non-uniform thickness - specifically, the reflectors have a first thickness in the central region and a second thickness (smaller than the first) in the end regions. This asymmetric thickness distribution allows the polarizer to maintain high polarization performance while reducing back-side reflectance, as the thinner end regions reduce the harmful reflective effects compared to uniform thickness structures
Solution Approach 2:
The patent applies local quality by varying the thickness of metal reflectors at different positions along their length. The central region maintains greater thickness for optimal polarization performance, while the end regions have reduced thickness to minimize back-side reflectance. This localized variation in reflector properties optimizes both polarization performance and reduces harmful reflections
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 provides excellent polarization performance, low back-side reflectance, and durability, making it suitable for various optical applications, including displays and polarized sunglasses, with improved heat and humidity resistance.
Implementation Method 1
the light of an electric field component parallel to the above wire-shaped objects is reflected, and the light of the electric field component perpendicular to the wire-shaped objects is transmitted
Data Source
AI summary
A wire-grid polarizer includes metal reflectors which are embedded in a large number of grooves formed in a one-dimensional grid pattern in the same direction and with the same period in the front surface of a transparent sheet, wherein the average width (a) of the metal reflectors is 200 nm or less, the ratio (b/a) of the average thickness (b) of the metal reflectors from the front side of the sheet to the tip in the backward direction to the above average width (a) is 4 to 25, in any cross-section perpendicular to the surface of the sheet, the shape of each of the metal reflectors in the vicinity of the tip in the thickness direction is such that it gradually becomes thinner in a linear or smoothly curved shape toward the tip, and the ratio of the average length (c) toward the tip of portions that gradually become thinner toward the tip to the above average width (a) is 1.2 or more.