Wavelength-Selective Absorptive Material for Infrared Sensors

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Solution Overview

Problem

Existing wavelength-selective absorptive materials exhibit low wavelength selectivity and high absorbance in the long wavelength range, which limits their effectiveness in infrared sensors, light sources, and radiation cooling systems.

Innovation Solution

A wavelength-selective absorptive material comprising a base material, a reflective layer, a high refractive index layer with a refractive index of 3.0 or more, and an infrared absorptive layer with a maximum absorption wavelength between 8 μm and 13 μm, where the product of the refractive index and thickness of the high refractive index layer is optimized for enhanced absorbency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional wavelength-selective absorptive materials are used, then they provide basic absorbency, but they exhibit low wavelength selectivity and high absorbance in the long wavelength range which limits their effectiveness

Engineering Contradiction:

Improvewavelength selectivityVSAvoidabsorbance in long wavelength range

Core Design Contradiction:

Manufacturing precisionVSLoss of energy

Solution Approach 1:

The absorptive material is divided into multiple functional layers: a reflective layer, a high refractive index layer with specific thickness (30-1000 nm) and refractive index (n≥3.0), and an infrared absorptive layer. Each layer serves a specific function to achieve wavelength-selective absorbency, with the high refractive index layer acting as an optical cavity to enhance absorption at specific wavelengths (8-13 μm) while maintaining low absorption at other wavelengths.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent optimizes specific parameters of the high refractive index layer including thickness (30-1000 nm), refractive index (n≥3.0), and optical path length (n×d between 1000-4875) to achieve resonant enhancement of infrared absorption at the atmospheric window wavelengths (8-13 μm) while suppressing absorption at other wavelengths, thereby achieving high wavelength selectivity.

Inventive Principle:

Principle #35Parameter changes

2Loss of energy

If the high refractive index layer thickness is increased to enhance absorbency, then absorption in the target wavelength range improves, but absorbance in the long wavelength range also increases reducing wavelength selectivity

Engineering Contradiction:

Improveabsorbance in 8-13 μm rangeVSAvoidwavelength selectivity

Core Design Contradiction:

Loss of energyVSManufacturing precision

Solution Approach 1:

The patent precisely controls the thickness (30-1000 nm) and refractive index (n≥3.0) of the high refractive index layer to achieve optimal optical resonance conditions. By adjusting these parameters, the optical path length (n×d) is controlled to be between 1000-4875, which creates constructive interference for wavelengths in the 8-13 μm range while maintaining destructive interference for other wavelengths, thereby achieving both high absorbency in the target range and high wavelength selectivity.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite structure combining a high refractive index material (such as TiO2, SiO2, or ZnO) with specific infrared absorptive materials. This composite approach allows the high refractive index layer to provide optical enhancement through interference effects while the infrared absorptive layer provides the actual absorption mechanism, achieving both high absorbency and high wavelength selectivity simultaneously.

Inventive Principle:

Principle #40Composite materials

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 material achieves excellent wavelength-selective absorbency with high absorbance in the 8 μm to 13 μm range and low absorbance in other ranges, improving the performance of infrared sensors, light sources, and radiation cooling systems by selectively absorbing infrared light.

Implementation Method 1

a high refractive index layer having a refractive index n of 3.0 or more with respect to infrared light having a wavelength range of 8 μm to 13 μm, having a thickness d of 30 nm to 1,000 nm... in which a product n×d of the refractive index n and the thickness d is more than 1,000 and less than 4,875

Methodology Applied

Scientific EffectOptical resonance: Resonance

Implementation Method 2

an infrared absorptive layer having a maximum absorption wavelength in the wavelength range of 8 μm to 13 μm

Methodology Applied

Scientific EffectAbsorption (EM radiation): Absorption (EM radiation)

Implementation Method 3

a reflective layer

Methodology Applied

Scientific EffectReflection: Reflection

Data Source

PatentUS10901124B1Wavelength-selective absorptive material, infrared sensor, wavelength-selective light source, and radiation cooling system

Publication Date: 2021.01.26 FUJIFILM CORP

AI summary

Provided is a wavelength-selective absorptive material which includes, in the following order: a base material; a reflective layer; and a high refractive index layer having a refractive index n of 3.0 or more with respect to infrared light having a wavelength range of 8 μm to 13 μm, having a thickness d of 30 nm to 1,000 nm, and containing a binder and flat metal particles; and an infrared absorptive layer having a maximum absorption wavelength in a wavelength range of 8 μm to 13 μm, in which a product n×d of the refractive index n and the thickness d is more than 1,000 and less than 4,875.