White Infrared Optical Filter Using a Colloidal Amorphous Array
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Solution Overview
Problem
Conventional infrared-transmissive filters have low infrared regular transmittance, leading to blurred motion capture images and high costs due to the use of dielectric multi-layer films, and they often appear black, lacking design quality and exhibiting angle-dependent color variations.
Innovation Solution
An optical filter with a colloidal amorphous array of fine particles dispersed in a transparent matrix, providing high infrared regular transmittance and a white appearance, achieved by optimizing particle diameter, refractive indices, volume fraction, and distribution to suppress Bragg reflection and enhance light resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a dielectric multi-layer film is used to achieve infrared transmittance, then the filter can transmit infrared rays, but the visible light reflected causes black color and poor design quality
Solution Approach 1:
The patent applies color changes by using a colloidal amorphous array that produces structural color through controlled light scattering. The fine particles are specifically designed to scatter visible light while transmitting infrared rays, transforming the filter's appearance from black to white without compromising infrared functionality. This structural color approach allows the filter to maintain its optical function while achieving desired aesthetic properties.
2Quantity of substance
If a dielectric multi-layer film is used for infrared transmittance, then the filter can transmit infrared rays, but the cost increases
Solution Approach 1:
The patent employs inexpensive spherical fine particles (such as silica or polystyrene) with diameters of 0.1-10 μm as the core filtering element. These particles can be mass-produced through conventional methods and dispersed in a transparent resin to form the filter. This approach replaces costly dielectric multi-layer films with a simpler, more economical particle-based system that achieves the same infrared transmittance function.
Solution Approach 2:
The patent utilizes parameter changes by controlling the size, concentration, and optical properties of the fine particles to achieve the desired infrared transmittance. By adjusting particle diameter (0.1-10 μm) and volume fraction (1-50%), the filter can be optimized for different applications without requiring complex multi-layer structures, thereby reducing manufacturing costs while maintaining performance.
3Quantity of substance
If the filter reflects visible light to block it, then infrared transmittance is achieved, but angle-dependent color variations occur
Solution Approach 1:
The patent achieves homogeneity by using a colloidal amorphous array of uniformly distributed spherical particles with consistent size and optical properties. This homogeneous structure ensures that light scattering occurs uniformly in all directions, eliminating angle-dependent color variations. The random but uniform distribution of particles creates a consistent white appearance regardless of the viewing angle, while maintaining high infrared transmittance.
4Shape
If fine particles are used to achieve white color, then design quality improves, but infrared regular transmittance may decrease
Solution Approach 1:
The patent applies local quality by designing particles with specific optical properties that differ for visible and infrared light. The spherical fine particles (0.1-10 μm) are engineered to scatter visible light effectively (producing white appearance) while remaining transparent to infrared rays. This localized optical behavior at the particle level allows simultaneous achievement of white color and high infrared transmittance without compromise.
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 optical filter achieves high infrared regular transmittance, maintains a white color appearance, and improves design quality by minimizing angle-dependent color variations and light resistance, while being cost-effective and suitable for various applications.
Implementation Method 1
visible light is scattered by Rayleigh scattering provided by the microscopic concaved and convexed pattern
Implementation Method 2
a fine-particle dispersion having an amorphous structure or a colloidal amorphous array expresses a bright structural color
Implementation Method 3
Conventional mainstream infrared-transmissive filters exhibit a black color to absorb visible light
Implementation Method 4
a dielectric multi-layer film transmitting infrared rays and reflecting and transmitting visible light
Data Source
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AI summary
Disclosed is an optical filter with L* measured by the SCE method being 20 or greater, wherein: the linear transmittance with respect to light with wavelengths being at least a portion of a wavelength range from 760 nm to 2000 nm is 60% or greater; and, before and after a light resistance test wherein light of a xenon arc lamp (average integrated illuminance of light with wavelengths from 300 nm to 400 nm: 120 W/m2) is shone for 300 hours, the absolute value of a change in C* measured by the SCE method using a spectroscopic colorimeter is 6 or less.