Wire Grid Polarizer Air Gaps for Imaging Element Transmittance
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Solution Overview
Problem
There is a strong demand for improving the transmittance and extinction ratio of wire grid polarizers in imaging elements, and existing manufacturing techniques often result in performance issues due to structural differences between the outer periphery and central parts of the polarizer, leading to light leakage and reduced reliability.
Innovation Solution
The implementation of air gaps in the space parts of the wire grid polarizer, along with a protective layer and a frame part structured similarly to the line parts, enhances the transmittance and extinction ratio while ensuring high reliability by reducing the average refractive index and preventing structural separation and light leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the formation pitch P0 of the wire grid is increased to improve transmittance and extinction ratio, then the manufacturing yield improves, but the polarization performance deteriorates because the condition P0 << λeff is no longer satisfied
Solution Approach 1:
The patent changes the physical state of the space parts from solid resin to air gaps (gaseous state). This parameter change in the refractive index (from ~1.5 for resin to 1.0 for air) allows the effective wavelength to increase, which in turn allows the formation pitch to be increased while maintaining the P0 << λeff condition, thus resolving the contradiction between manufacturing yield and polarization performance
Solution Approach 2:
The patent introduces air (inert atmosphere) into the space parts of the wire grid polarizer. This creates an environment with lower refractive index that improves both the polarization performance and allows for larger formation pitch, thereby improving manufacturing yield without sacrificing optical performance
2Ease of manufacture
If the outer periphery of the wire grid polarizer is manufactured with the same process as the central part, then the manufacturing process is simplified, but the outer periphery frequently separates from the photoelectric conversion unit due to structural differences
Solution Approach 1:
The patent applies local quality by making the space parts throughout the wire grid polarizer (including outer periphery) have the same air gap structure. This ensures uniform optical and mechanical properties across the entire device, preventing separation at the outer periphery while maintaining consistent manufacturing processes
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 increases the formation pitch of the wire grid polarizer, improves manufacturing yield, and enhances the reliability of the imaging element by reducing light leakage and structural differences, thereby improving the overall performance and reliability of the imaging apparatus.
Implementation Method 1
When the average refractive index determined on the basis of the substance existing in the space parts is designated as n0, the effective wavelength λeff is expressed as (λ0/n0). The average refractive index n0 takes a value obtained by adding up the products of the refractive index and the volume of the substances existing in the space parts and then dividing the resultant by the volume of the space parts.
Implementation Method 2
the electromagnetic wave having reached the wire grid polarizer includes a vertical polarization component and a lateral polarization component, and the electromagnetic wave having passed through the wire grid polarizer becomes linearly polarized light in which the vertical polarization component is dominant
Data Source
AI summary
There is provided an imaging element including a photoelectric conversion unit formed in a substrate and a wire grid polarizer disposed at a light-incident side of the photoelectric conversion unit. In addition, the wire grid polarizer includes a plurality of strip-shaped portions, where air gaps exist between adjacent strip-shaped portions. Further, a protective layer is formed on the wire grid polarizer.