Optical Filter with Dispersed Fine Particles for Infrared Transmittance
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Solution Overview
Problem
Conventional infrared-transmissive filters are costly and suffer from low infrared regular transmittance, leading to blurred contours in motion capturing applications and poor design quality due to their black color.
Innovation Solution
An optical filter comprising a matrix with fine particles dispersed within, where the fine particles have a specific parameter Ds ranging from 8.0 to 30, ensuring high infrared regular transmittance and a white color appearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dielectric multi-layer film is used to reflect visible light and transmit infrared rays, then the filter achieves infrared transmittance and visible light reflection, but the film is costly and has low infrared regular transmittance causing blurred contours in motion capturing
Solution Approach 1:
The patent changes the particle size parameter of the dispersed phase from conventional ranges to specifically 0.01-1 μm, and controls the volume fraction at 10-70%. These parameter changes enable the filter to achieve high infrared regular transmittance (60% or higher) while maintaining visible light diffusion and white appearance, resolving the contradiction between infrared transmittance and manufacturing cost by providing a simpler, more effective formulation approach
Solution Approach 2:
The patent creates a composite material system consisting of a transparent or infrared-transmissive resin matrix combined with specifically sized particles (0.01-1 μm) having different refractive indices. This composite structure achieves both visible light diffusion (through refractive index differences) and infrared transmission (through appropriate particle sizing), replacing costly dielectric multi-layer films with a more economical composite material solution
2Reliability
If the filter uses a black color to absorb visible light, then the filter achieves infrared transmittance, but the design quality is poor
Solution Approach 1:
The patent applies local quality by creating different optical properties at different scales: at the micro-scale, particles with specific sizes (0.01-1 μm) and refractive index differences provide visible light diffusion and white appearance; at the macro-scale, the overall structure maintains high infrared transmittance. This multi-scale local quality approach allows the filter to exhibit white color (improving design quality) while maintaining infrared transmission performance
Solution Approach 2:
The patent fundamentally changes the color mechanism from absorption (black color absorbing visible light) to scattering (particles scattering visible light to produce white appearance). By using particles with specific size ranges and refractive index differences, the filter achieves white color through light scattering while maintaining infrared transmission, thereby improving design quality without sacrificing functional performance
3Shape
If the infrared receiver/transmitter is viewed at different angles, then the color varies due to visible light reflection, but a consistent white appearance is desired
Solution Approach 1:
The patent achieves homogeneity in optical properties by using randomly dispersed particles with specific size ranges (0.01-1 μm) throughout the resin matrix. This random homogeneous distribution ensures that visible light is scattered uniformly in all directions, producing a consistent white appearance from any viewing angle, while the overall homogeneous structure maintains simple device design without complex optical components
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 a high infrared regular transmittance of 60% or higher for wavelengths between 760 nm and 2000 nm, maintaining a white color appearance regardless of viewing angle, thus enhancing design quality and motion capturing clarity.
Implementation Method 1
visible light is scattered by Rayleigh scattering provided by the microscopic concaved and convexed pattern
Implementation Method 2
an infrared-transmissive filter exhibiting a white color and having a high infrared regular transmittance
Data Source
AI summary
An optical filter (10) comprises a matrix (12) and fine particles (14) dispersed in the matrix (12), wherein the fine particles (14) have a parameter Ds of 8.0 to 30 inclusive, Ds being determined by a USAXS pattern and given by Ds=λ/(B·cos θ·Ra), where λ is the X-ray wavelength, θ is one half the scattering angle 2θ(rad) providing a scattering intensity peak, B is the half width (FWHM, rad) of the peak, and Ra is the average particle size of the fine particles (14).