Optical Filter With Absorption Layer For Wide-Angle Transmittance
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Solution Overview
Problem
Optical filters used in image capturing devices face challenges in maintaining high transmittance in the visible light range while effectively blocking ultraviolet and infrared light, particularly due to issues of reflection and absorption at the interfaces of multilayer structures, which degrade performance especially in wide-angle cameras.
Innovation Solution
An optical filter design featuring a substrate with a transmittance control layer having a specific refractive index difference with the substrate, combined with a light absorption layer and potentially a dielectric multilayer film, to optimize transmittance and blocking characteristics across various angles of incidence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a multilayer structure is used to block ultraviolet and infrared light, then blocking effectiveness is improved, but transmittance in the visible light range decreases due to reflection and absorption at interfaces
Solution Approach 1:
The patent extracts the light blocking function from the multilayer dielectric structure and assigns it to a single-layer absorption layer made of infrared absorbing glass. This eliminates the need for multiple interfaces that cause reflection and absorption losses, thereby maintaining high transmittance in the visible range while achieving effective blocking of ultraviolet and infrared light.
Solution Approach 2:
The patent uses composite materials by combining infrared absorbing glass (containing CuO) with specific dye materials in the absorption layer. This composite structure enables simultaneous absorption of ultraviolet and infrared wavelengths while maintaining high visible light transmittance, resolving the contradiction between blocking effectiveness and energy loss.
2Object-affected harmful factors
If infrared absorbing glass with CuO is used as substrate, then blocking of near infrared light is improved, but transmittance decrease becomes larger due to absorption characteristics
Solution Approach 1:
The patent applies local quality by using infrared absorbing glass specifically for its infrared blocking capability while controlling the CuO content to minimize visible light absorption. The absorption layer is designed with specific thickness and dye concentration to provide ultraviolet blocking without affecting visible transmittance, thus resolving the contradiction between infrared blocking and visible light energy loss.
3Adaptability or versatility
If wide-angle camera design is implemented, then adaptability is improved, but maintaining transmission and blocking characteristics becomes more difficult
Solution Approach 1:
The patent uses parameter changes by optimizing the refractive index, thickness, and material composition of the absorption layer to maintain consistent optical characteristics across wide angles of incidence. The single-layer structure with controlled parameters ensures reliable transmission and blocking characteristics regardless of the incident angle, enabling wide-angle camera applications.
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 enhances transmittance in the visible light range while effectively blocking ultraviolet and infrared light, reducing unwanted reflection and absorption, thereby improving image quality even at wider angles of incidence.
Implementation Method 1
an absolute value of a difference in a refractive index of the transmittance control layer with respect to a refractive index of the substrate is in a range of 2% to 10%
Implementation Method 2
The light absorption layer is a film designed to block light of an unnecessary wavelength by absorption using various dyes
Implementation Method 3
the dielectric multilayer film described above is usually a film formed by repeatedly stacking a high refractive index dielectric material and a low refractive index dielectric material, and such a film can block light of unnecessary wavelengths by reflection
Implementation Method 4
Infrared absorbing glass is a glass filter in which CuO is added to glass to selectively absorb light in the near infrared wavelength region
Data Source
AI summary
This invention provides an optical filter and its use. In the present invention, an optical filter capable of securing high transmittance in a necessary wavelength range (e.g., visible light region) while effectively blocking light in an unnecessary wavelength range (e.g., ultraviolet, and infrared ray) and its utilization can be provided.