Absorption Type Near Infrared Filter With Multilayer Films
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Solution Overview
Problem
Current near-infrared filters for photographic devices suffer from issues such as color shift, chromatic aberration, stray light, and ghosting, which affect image quality by failing to effectively block infrared interference.
Innovation Solution
An absorption type near-infrared filter comprising a first multilayer film, a second multilayer film, and an absorption film with an infrared absorbing dye, where the absorption film has specific transmittance and reflectivity differences to optimize infrared absorption and minimize interference across various wavelengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional filter is used to block infrared light, then infrared interference is reduced, but color shift and chromatic aberration occur affecting image quality
Solution Approach 1:
The filter is divided into multiple functional layers: a first multilayer film structure for reflectivity control, an absorption film with infrared absorbing dye for absorption, and a second multilayer film structure for additional reflectivity control. This segmentation allows each layer to address specific aspects of infrared blocking while minimizing side effects like color shift and chromatic aberration.
Solution Approach 2:
The filter combines multiple materials with different properties: dielectric materials in the multilayer films for reflectivity, and infrared absorbing dye in the absorption film for selective infrared absorption. This composite structure achieves superior infrared blocking performance while maintaining visible light transmission and color accuracy.
2Object-affected harmful factors
If the absorption film has high infrared absorption, then infrared blocking is improved, but visible light transmission may be affected causing color shift
Solution Approach 1:
The absorption film is designed with specific local properties: infrared absorbing dye at controlled concentrations (0.5-5% by weight) to selectively absorb infrared wavelengths while maintaining high visible light transmission. The multilayer films are engineered with specific thicknesses and refractive indices to control reflectivity in specific wavelength ranges, allowing independent optimization of infrared blocking and visible light transmission.
Solution Approach 2:
The filter utilizes parameter changes in material properties and structural characteristics to achieve wavelength-selective filtering. By adjusting the concentration of infrared absorbing dye, the thickness of multilayer films, and the refractive indices of materials, the filter achieves high infrared absorption while maintaining excellent visible light transmission and minimizing color shift.
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 filter effectively addresses color shift, chromatic aberration, stray light, and ghosting by precisely controlling the transmittance and reflectivity differences, thereby enhancing image quality by reducing infrared interference.
Implementation Method 1
The absorption film comprises an infrared absorbing dye with a weight percentage between 1% and 3%
Implementation Method 2
the difference between the wavelength with the transmittance at 80% of the absorption film and the wavelength with the reflectivity at 80% of the first multilayer film
Data Source
AI summary
An absorption type near-infrared filter comprising a first multilayer film, a second multilayer film, and an absorption film, wherein in the ultraviolet band, the difference of between the wavelength with the transmittance at 80% of the absorbing film and the wavelength with the reflectivity at 80% of the first multilayer film falls in the range between 25 nm and 37 nm, the difference of between the wavelength with the transmittance at 50% of the absorbing film and the wavelength with the reflectivity at 50% of the first multilayer film falls in the range between 6 nm and 14 nm, and the difference of between the wavelength with the transmittance at 20% of the absorbing film and the wavelength with the reflectivity at 20% of the first multilayer film falls in the range between −6 nm and 2.5 nm.