Squarylium Optical Filter Fluorescence Quenching
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Solution Overview
Problem
Conventional optical filters, such as near-infrared cut filters, often generate scattered light during light absorption, which can degrade image quality in camera systems due to the fluorescence properties of squarylium-based dyes used in them.
Innovation Solution
An optical filter is developed using a combination of a squarylium-based compound and a specific compound that absorbs or quenches fluorescence, such as a phthalocyanine-based or cyanine-based compound, to minimize scattered light and enhance transmittance properties, with a resin substrate containing these dyes and a near-infrared reflecting film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a squarylium-based dye is used in the optical filter to achieve steep absorption and high visible light transmittance, then the absorption performance is improved, but scattered light is generated due to fluorescence which degrades image quality
Solution Approach 1:
A fluorescence quenching compound is introduced as an intermediary substance that absorbs the fluorescence emitted by the squarylium-based dye. This mediator compound receives the harmful fluorescence energy and converts it to harmless forms, preventing the scattered light from reaching the image sensor while preserving the primary light absorption function of the squarylium dye.
Solution Approach 2:
The fluorescence property of the squarylium-based dye, which originally causes scattered light and image quality degradation, is converted into a beneficial effect. The fluorescence quenching compound absorbs this fluorescence and converts it to thermal energy or other non-scattering forms, transforming the harmful scattered light into harmless energy dissipation while maintaining the steep absorption characteristics of the original dye.
2Measurement precision
If a near-infrared absorbing dye is incorporated into a transparent resin to create a near-infrared cut filter, then the near-infrared absorption is achieved, but fluorescence scattering occurs which lowers image quality
Solution Approach 1:
The optical filter is constructed as a composite material system containing three components: the transparent resin base material, the squarylium-based near-infrared absorbing dye, and the fluorescence quenching compound. This composite structure combines the light absorption capability of the squarylium dye with the fluorescence suppression capability of the quenching compound, achieving both near-infrared absorption and scattered light reduction simultaneously.
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 reduces scattered light and improves transmittance, resulting in an optical filter that maintains image quality and visibility correction for solid-state image pickup devices and camera modules.
Implementation Method 1
a squarylium-based compound which has an absorption maximum in a wavelength region of not less than 600 nm but less than 800 nm
Implementation Method 2
since the squarylium-based dye generally has fluorescence in view of its molecular structure, it sometimes generates scattered light during light absorption
Implementation Method 3
at least one compound (B) which absorbs or quenches fluorescence of the squarylium-based compound (A)
Data Source
AI summary
The problem of the present invention is to overcome drawbacks of conventional optical filters such as near-infrared cut filters and to provide an optical filter which generates little scatted light even during light absorption and has excellent transmittance property. The optical filter of the present invention is characterized by containing a squarylium-based compound and a compound which absorbs or quenches fluorescence of the squarylium-based compound. The optical filter of the present invention preferably contains a near-infrared absorbing dye containing a squarylium compound (A) and at least one compound (B) selected from the group consisting of a phthalocyanine-based compound (B-1) and a cyanine-based compound (B-2).