Thermochromic Window Filter for Infrared Imaging Saturation
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Solution Overview
Problem
Current technologies face challenges in effectively limiting solar power transmission and protecting infrared imaging systems from intense radiation sources, particularly in environments where both hot and cold targets are present, due to saturation effects and high infrared emission.
Innovation Solution
A novel thermochromic composition is developed, incorporating thermochromic nanoparticles like VO2 and light-absorbing nanoparticles, embedded in a transparent matrix, which enhances light intensity modulation and shortens reaction time, allowing for selective control of transparency to attenuate hot areas while transmitting cold areas, thus improving visibility of low infrared emitting targets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional thermochromic materials are used to limit solar power transmission, then infrared radiation from hot targets is attenuated, but visibility of cold targets is also reduced due to saturation effects
Solution Approach 1:
The patent modifies the optical parameters of thermochromic materials by doping vanadium dioxide with tungsten to reduce the phase transition temperature from 68°C to approximately 24°C, enabling the material to respond to ambient temperature changes rather than extreme heat, thus allowing cold targets to remain visible while attenuating hot targets
Solution Approach 2:
The patent creates a composite material system combining thermochromic nanoparticles (vanadium dioxide or tungsten-doped vanadium dioxide) with a transparent matrix material, where the composite exhibits enhanced thermochromic performance and selective infrared transmission properties that simultaneously protect against hot targets and maintain visibility of cold targets
2Object-affected harmful factors
If thermochromic materials with high transition temperature are used, then protection from intense radiation is achieved, but response time is delayed and reaction to ambient temperature changes is slow
Solution Approach 1:
The patent changes the phase transition temperature parameter of the thermochromic material from high (68°C for pure VO2) to low (approximately 24°C for tungsten-doped VO2), enabling the material to respond rapidly to ambient temperature fluctuations and provide timely protection while maintaining fast response characteristics
3Temperature
If pure vanadium dioxide is used as thermochromic material, then phase transition occurs at 68°C, but this temperature is too high for effective solar power limiting in ambient conditions
Solution Approach 1:
The patent applies doping with tungsten to alter the phase transition temperature parameter of vanadium dioxide from 68°C to approximately 24°C, making the material effective for solar power limiting under ambient temperature conditions where the transition can be triggered by moderate heating from solar radiation
Solution Approach 2:
The patent introduces tungsten dopants at specific concentrations (0.1-10 atomic percent) into the vanadium dioxide lattice to locally modify the electronic structure and phase transition behavior, creating material with optimized properties for ambient temperature operation while maintaining the bulk thermochromic effect
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 limits solar power transmission and protects infrared imaging systems by attenuating high-power radiation while preserving visibility of low infrared emitting targets, even in the presence of high infrared emitting backgrounds, through enhanced absorption and phase transformation at lower light intensities.
Implementation Method 1
the semiconductor-to-metal transition by solid-state materials, such as vanadium and titanium oxides
Implementation Method 2
In the phenomenon of thermochromism the optical properties of a material change reversibly as a function of temperature
Implementation Method 3
light-absorbing nanoparticles (1 to 100 nanometers in size) that exhibit strong absorption of the impinging light
Implementation Method 4
enhancing the heating of the neighboring thermochromic particles by the sun-light absorbing nanoparticles
Data Source
AI summary
The present invention relates to an optical window-filter including a thermochromic material and a light absorbing material. An absorption of light by the light absorbing material generates heat that causes phase transformation of the thermochromic material. The present invention further relates to a filter for an infrared imaging system having detectors sensitive to radiation in an infrared transmission spectrum. The filter includes a thermochromic material and a light-absorbing material. An absorption of high-power radiation in the infrared transmission spectrum by the light-absorbing material generates heat that causes phase transformation of the thermochromic material to attenuate the high-power radiation while transmitting substantially unaffected low-power radiation in the infrared transmission spectrum.