Colloidal Optical Filter for Infrared Transmission and White Back-Scattering
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Solution Overview
Problem
Conventional infrared-transmissive filters are costly and have low infrared regular transmittance, leading to blurred contours in motion capturing applications.
Innovation Solution
An optical filter with a colloidal amorphous array of fine particles dispersed in a transparent matrix, achieving high infrared regular transmittance and isotropic back-scattering characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dielectric multi-layer film is used as an infrared-transmissive filter, then visible light reflection and infrared transmission are achieved, but the filter is costly and has low infrared regular transmittance
Solution Approach 1:
The patent changes the material composition parameters by using a transparent resin containing colloidal particles with specific size distributions (average diameter 1-10 μm, with at least 20% by volume having diameter 3-10 μm). This parameter change achieves high infrared regular transmittance (60% or more at 950 nm) while maintaining visible light diffuse reflectance, eliminating the need for costly dielectric multi-layer films.
Solution Approach 2:
The patent creates a composite material system consisting of a transparent resin matrix (such as PMMA, polycarbonate, or polyester) containing dispersed colloidal particles. This composite structure combines the transparency and formability of the resin with the optical scattering properties of the colloidal particles, achieving both high infrared transmittance and visible light reflection without requiring complex multi-layer dielectric structures.
2Measurement precision
If a dielectric multi-layer film is used, then infrared transmission is achieved, but the contour of captured objects becomes blurred due to low infrared regular transmittance
Solution Approach 1:
The patent optimizes the colloidal particle size parameters, specifically setting the average diameter to 1-10 μm with at least 20% by volume having diameter 3-10 μm. This specific size range allows the particles to effectively scatter visible light while maintaining high regular transmittance for infrared wavelengths, thereby preserving the contour clarity of captured objects in motion capturing applications.
3Adaptability or versatility
If the filter absorbs visible light to achieve infrared transmission, then infrared selectivity is improved, but design quality deteriorates due to black color
Solution Approach 1:
The patent changes the optical interaction mechanism from absorption to scattering. By using colloidal particles with appropriate size and concentration in a transparent resin, the filter scatters visible light to produce a white appearance rather than absorbing it to produce black. This scattering mechanism maintains infrared transmission while achieving a visually appealing white color that improves design quality.
Solution Approach 2:
The composite material consisting of transparent resin and colloidal particles creates a white appearance through light scattering while maintaining infrared transparency. This composite structure eliminates the need for black absorbing materials, providing both functional infrared selectivity and aesthetic white appearance suitable for various design 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 optical filter provides high infrared regular transmittance and a white color, improving design quality and enabling clear motion capturing images.
Implementation Method 1
fine particles which form at least a colloidal amorphous array
Implementation Method 2
having a regular transmittance of 60% or higher for light having a wavelength in at least a part of a wavelength range not shorter than 950 nm and not longer than 2000 nm
Data Source
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AI summary
This optical filter has a back-scattering property, and the linear transmittance thereof to light of at least some wavelengths in the wavelength range of 760-2000 nm is 60% or higher. Where: the azimuth from an incidence plane when the polar angle of the direction of incidence of incident light is 0° is 20°, and the value of a bidirectional reflectance distribution function in the direction where the polar angle is -60° is BRDF (0°; 20°, -60°); the azimuth from an incidence plane when the polar angle of the direction of incidence of incident light is 30° is 20°, and the value of a bidirectional reflectance distribution function in the direction where the polar angle is -60° is BRDF (30°; 20°, -60°); and the azimuth from an incidence plane when the polar angle of the direction of incidence of incident light is 60° is 20°, and the value of a bidirectional reflectance distribution function in the direction where the polar angle is -60° is BRDF (60°; 20°, - 60°), then, for the incident light having at least some wavelengths in the wavelength range of visible light, |BRDF (0°; 20°, -60°) - BRDF (30°; 20°, -60°)|/BRDF (0°; 20°, -60°) is 1.0 or lower, and |BRDF (0°; 20°, -60°) - BRDF (60°; 20°, -60°) |/BRDF (0°; 20°, -60°) is 1.0 or lower.