Dual-Purpose Wire Grid Polarizer for Ghosting Reduction
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Solution Overview
Problem
Existing wire grid polarizers face challenges in optimizing both efficiency and contrast, as they are typically designed to prioritize either high reflection or high absorption of one polarization, which can lead to interference in optical systems and suboptimal light image resolution.
Innovation Solution
A wire grid polarizer design featuring an array of parallel, elongated rods with a reflective wire sandwiched between a transparent and an absorptive rib over a substrate, allowing for adjustable positioning of the ribs to optimize reflection and absorption based on incident light direction, thereby achieving high efficiency and contrast.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a wire grid polarizer is designed for high reflection of s-polarization, then efficiency (Tp*Rs) is improved, but absorption is reduced leading to potential interference in optical systems
Solution Approach 1:
The patent applies local quality by making one rib absorptive and the other transparent/reflective. This allows different regions of the same rod structure to perform different functions: the absorptive rib eliminates harmful reflections through absorption, while the transparent rib maintains high transmission efficiency. This resolves the contradiction by locally optimizing each rib's material property rather than using uniform materials throughout.
Solution Approach 2:
The patent uses composite materials by combining absorptive material in one rib with transparent or reflective material in the other rib. This composite approach allows the polarizer to simultaneously achieve high efficiency (through the transparent/reflective rib) and eliminate interference (through the absorptive rib), resolving the contradiction between efficiency and harmful reflections.
2Object-generated harmful factors
If a wire grid polarizer is designed for high absorption of s-polarization, then interference is minimized, but efficiency (Tp*Rs) decreases
Solution Approach 1:
The patent applies local quality by making one rib absorptive and the other transparent/reflective. This allows different regions of the same rod structure to perform different functions: the absorptive rib eliminates harmful reflections through absorption, while the transparent rib maintains high transmission efficiency. This resolves the contradiction by locally optimizing each rib's material property rather than using uniform materials throughout.
Solution Approach 2:
The patent uses composite materials by combining absorptive material in one rib with transparent or reflective material in the other rib. This composite approach allows the polarizer to simultaneously achieve high efficiency (through the transparent/reflective rib) and eliminate interference (through the absorptive rib), resolving the contradiction between efficiency and harmful reflections.
3Use of energy by moving object
If a wire grid polarizer is optimized for high transmission of p-polarization, then light-source power requirements are minimized, but contrast (Tp/Ts) may be compromised
Solution Approach 1:
The patent applies local quality by making one rib absorptive and the other transparent/reflective. This allows different regions of the same rod structure to perform different functions: the absorptive rib eliminates harmful reflections through absorption, while the transparent rib maintains high transmission efficiency. This resolves the contradiction by locally optimizing each rib's material property rather than using uniform materials throughout.
Solution Approach 2:
The patent uses composite materials by combining absorptive material in one rib with transparent or reflective material in the other rib. This composite approach allows the polarizer to simultaneously achieve high efficiency (through the transparent/reflective rib) and eliminate interference (through the absorptive rib), resolving the contradiction between efficiency and 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
This design achieves efficiency of at least 85% and contrast of up to 4000 for visible light, effectively minimizing ghosting in image projectors by selectively reflecting or absorbing s-polarization, enhancing image resolution and reducing light-source power requirements.
Implementation Method 1
Wire grid polarizers (WGP for singular or WGPs for plural) can transmit one polarization (e.g. p-polarization) and reflect or absorb an opposite polarization (e.g. s-polarization). High reflectivity of the opposite polarization (e.g. high Rs) can be important because some applications use both polarized light beams
Implementation Method 2
Each of the rods can include a reflective wire sandwiched between a transparent rib and an absorptive rib
Implementation Method 3
High absorption/low reflectivity of the opposite polarization (e.g. low Rs) can be important because reflection of this polarization (Rs) can interfere with the optical system. For example, the reflected s-polarization can cause ghosting in an image projector
Data Source
AI summary
A WGP 10 can include an array of parallel, elongated rods 14 located over a surface of a transparent substrate 11 with gaps 15 between adjacent rods 14. Each of the rods 14 can include a reflective wire 13 sandwiched between ribs 12. One of the ribs 12 can be a transparent rib and one can be an absorptive rib. The WGP 10 can have high efficiency and high contrast for light entering on the transparent rib side and low Rs for light entering on the absorptive rib side.