Iron Oxide Multilayer Filter for Near Infrared Attenuation
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Solution Overview
Problem
Existing thin-film type filters for attenuating near infrared rays lack satisfactory optical performance and environmental resistance, and the production methods are not stable.
Innovation Solution
A thin-film type filter with a multilayer film structure comprising layers of iron oxide and other materials with a refractive index lower than iron oxide, where the ratio of iron to oxygen atoms in each iron oxide layer is between 4/3 and 3/2, and the attenuation coefficient is at least 0.1 for specific wavelengths between 700 and 2000 nanometers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional thin-film type filters are used to attenuate near infrared rays, then the filter structure is simple, but the optical performance and environmental resistance are not satisfactory
Solution Approach 1:
The patent employs composite material structure by combining multiple layers of different materials (iron oxide layer, silicon oxide layer, and plastic substrate) to achieve superior optical performance and environmental resistance. The iron oxide layer provides attenuation functionality while the silicon oxide layer enhances environmental stability, creating a composite structure that resolves the contradiction between reliability and complexity.
Solution Approach 2:
The filter is segmented into multiple functional layers with distinct roles: the iron oxide layer for light attenuation, the silicon oxide layer for environmental protection and optical control, and the plastic substrate for structural support. This segmentation allows each layer to be optimized independently, achieving high reliability without excessive overall complexity.
2Reliability
If plastic with attenuating agent is used to produce filter, then the filter can attenuate light, but dedicated equipment and lot of time for adjustment are required leading to higher production cost
Solution Approach 1:
The patent controls attenuation performance by precisely controlling the thickness parameters of each layer (iron oxide layer thickness, silicon oxide layer thickness) rather than relying on mixing ratios and adjustment processes. This parameter-based control method simplifies the manufacturing process while maintaining reliable attenuation performance, as thickness can be controlled during deposition without requiring post-production adjustment.
Solution Approach 2:
The patent replaces the mechanical mixing process (mixing plastic and attenuating agent) with a thin-film deposition process. Instead of mechanically combining materials in bulk, the attenuation functionality is achieved through controlled deposition of iron oxide and silicon oxide layers, eliminating the need for dedicated mixing equipment and adjustment processes.
3Productivity
If conventional production methods are used, then the production process is simple, but the production stability is not high
Solution Approach 1:
The patent achieves high production stability by controlling critical parameters (layer thickness, material composition ratios, deposition conditions) during the thin-film formation process. This parameter control approach ensures consistent optical performance across batches, improving productivity stability compared to conventional methods that rely on post-production adjustment.
Solution Approach 2:
The patent performs preliminary action by forming the iron oxide and silicon oxide layers with precise thickness control during the deposition process itself, rather than requiring subsequent adjustment. The desired optical performance is built into the structure during manufacturing, ensuring production stability without complex post-processing.
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 achieves high accuracy in determining transmittance and provides high environmental resistance, allowing for the production of filters with transmittance values ranging from 10% to 90%.
Implementation Method 1
a ratio of the number of iron atoms to the number of oxygen atoms in each layer of iron oxide is equal to or greater than 4/3 and less than 3/2 and an attenuation coefficient of each layer of iron oxide is equal to or greater than 0.1 for light of wavelength of a certain wavelength in a wavelength from 700 nanometers to 2000 nanometers
Data Source
AI summary
A thin film type filter for attenuating light comprising a multilayer film including a layer or layers of iron oxide and a layer or layers of other material having refractive index lower than refractive index of iron oxide, wherein the multilayer is made up of alternate layers of iron oxide and of other material, a ratio of the number of iron atoms to the number of oxygen atoms in each layer of iron oxide is equal to or greater than 4/3 and less than 3/2 and an attenuation coefficient of each layer of iron oxide is equal to or greater than 0.1 for light of wavelength of a certain wavelength in a wavelength from 700 nanometers to 2000 nanometers.