Resonant Grating Polarization Element for Projectors
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Solution Overview
Problem
Existing wire grid polarization elements for liquid crystal projectors require complex structures and high manufacturing costs due to the need for additional absorbing layers to effectively absorb unwanted polarized light, which can lead to image quality degradation and increased costs.
Innovation Solution
A polarization element with a resonant grating structure featuring thin metal wires and protruding sections with varying heights and proportions, arranged at pitches shorter than the incident light wavelength, which excites surface plasmon resonance to selectively absorb linearly polarized light, eliminating the need for an absorbing layer and simplifying the structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an absorbing layer is added to the wire grid polarization element to absorb unwanted polarized light, then the image quality and grayscale expression are improved, but the element structure becomes complicated and manufacturing cost increases
Solution Approach 1:
The patent combines the polarization function and the unwanted light absorption function into a single integrated wire grid structure. The wire grid is designed with specific parameters (wire diameter, pitch, length) that enable it to simultaneously polarize light and absorb unwanted polarized light through controlled reflection, eliminating the need for a separate absorbing layer.
Solution Approach 2:
The wire grid polarization element is designed to perform multiple functions: it acts as both a polarization separator and an absorber of unwanted polarized light. By optimizing the wire grid parameters, the element achieves both polarization separation and absorption of reflected light, reducing the overall system complexity.
2Reliability
If an absorbing layer is added to the wire grid polarization element to absorb unwanted polarized light, then the grayscale expression is improved, but the manufacturing cost increases
Solution Approach 1:
The patent combines the polarization function and the unwanted light absorption function into a single integrated wire grid structure. The wire grid is designed with specific parameters (wire diameter, pitch, length) that enable it to simultaneously polarize light and absorb unwanted polarized light through controlled reflection, eliminating the need for a separate absorbing layer.
Solution Approach 2:
The wire grid polarization element is designed to perform multiple functions: it acts as both a polarization separator and an absorber of unwanted polarized light. By optimizing the wire grid parameters, the element achieves both polarization separation and absorption of reflected light, reducing the overall system complexity.
3Reliability
If the pitch of the wire grid is made shorter than the wavelength of incident light to improve polarization separation, then the polarization separation performance is improved, but the manufacturing precision requirement increases
Solution Approach 1:
The patent optimizes the wire grid parameters including wire diameter, pitch, and length to achieve effective polarization separation and absorption. By carefully selecting these parameters, the invention achieves good performance while maintaining reasonable manufacturing precision requirements.
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 configuration enhances grayscale expression and image quality by reducing reflectance across a broad wavelength range, increasing design margin, and lowering manufacturing costs by eliminating the need for additional absorbing layers.
Implementation Method 1
by adopting the resonant grating structure having the protruding sections arranged on the thin metal wires at a pitch shorter than the wavelength of the incident light, it becomes possible to develop the surface plasmon resonance (SPR) to thereby selectively absorb the linearly polarized light TE (unwanted polarized light) with a specific wavelength entering the polarization element
Implementation Method 2
When the linearly polarized light TE enters the resonant grating structure described above, the evanescent light is generated. The wave number thereof and the wave number of the surface plasmon can be made equal to each other using the evanescent light, and thus the surface plasmon can be excited. Since the energy of the incident light is consumed for the excitation of the surface plasmon, the reflection toward the entering direction of the light can be reduced.
Data Source
AI summary
A polarization element includes: a substrate; and a plurality of grid sections arranged on the substrate, wherein the grid sections each have protruding sections and recessed sections alternately arranged in a longitudinal direction of the grid sections at a pitch shorter than a wavelength of incident light, in the plurality of grid sections, the arrangement pitch P of the protruding sections is the same, and a proportion (D=L/P) of a length L of the protruding section to the arrangement pitch P of the protruding sections is the same, and a height of the protruding sections is different between the grid sections adjacent to each other.