Aperture Structure for Optical Windows Low Reflectance
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Solution Overview
Problem
Traditional aperture structures for optical devices exhibit high reflectance at certain wavelengths, leading to undesirable purplish or reddish hues when viewed from wider angles, failing to meet the requirements of low reflection and high absorbance across the visible light spectrum.
Innovation Solution
An aperture structure comprising an optical cavity layer with a dielectric material, a light absorbing layer with a metal or metal alloy, and a blocking layer, optimized to achieve a reflectance of less than 5% across the 400 nm to 700 nm range, ensuring high absorbance and appearing black to an observer from various angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional aperture structures are used, then manufacturing is simpler, but reflectance is high at certain wavelengths causing purplish or reddish hues at larger viewing angles
Solution Approach 1:
The patent applies composite materials by combining multiple dielectric layers with different refractive indices (e.g., silicon dioxide with n≈1.45, silicon nitride with n≈2.0, tantalum pentoxide with n≈2.1) to create an optical cavity structure. This multi-material composite approach enables broadband light absorption across 400-700 nm wavelength range while maintaining low reflectance at various viewing angles, resolving the color distortion issue without significantly complicating manufacturing
Solution Approach 2:
The patent utilizes parameter changes by precisely controlling the thickness of each dielectric layer (ranging from 10 nm to 200 nm) and their refractive indices to optimize optical interference effects. By adjusting these parameters, the structure achieves minimal reflectance across the visible spectrum at viewing angles up to 30 degrees, eliminating the purplish or reddish hues while maintaining manufacturability through standard thin-film deposition techniques
2Loss of energy
If aperture structure thickness is increased to reduce reflectance, then absorbance improves, but device complexity increases
Solution Approach 1:
The patent applies local quality by creating spatially varying dielectric layers with different refractive indices and thicknesses within the optical cavity. Each layer is locally optimized to address specific wavelength ranges and viewing angles, achieving high absorbance (95-99%) across the entire visible spectrum without requiring excessive overall thickness or adding unnecessary structural complexity
Solution Approach 2:
The patent transitions from a single-layer approach to a multi-layer dimensional structure, where each dielectric layer contributes to absorption at different wavelengths and angles. This dimensional expansion in the vertical stacking direction enables comprehensive light trapping with controlled complexity, achieving broadband absorption without proportionally increasing device complexity
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 aperture structure effectively minimizes reflectance and maximizes absorbance, maintaining a black appearance across a wide range of angles and wavelengths, addressing the limitations of traditional designs.
Implementation Method 1
The optical cavity layer includes a dielectric material... characterized by a refractive index of about 1.4 or greater, as measured at a wavelength of 550 nm, a transmittance of at least about 50% for each wavelength of light in a range 400 nm to 700 nm
Implementation Method 2
The light absorbing layer includes a metal or a metal alloy and is characterized by an extinction coefficient k of at least 1, as measured at a wavelength of 550 nm
Implementation Method 3
The blocking layer includes a metal or a metal alloy and is characterized by an optical density of at least 3 at each wavelength of light in the range from 400 nm to 700 nm
Implementation Method 4
The aperture structure includes a reflectance of less than 5% at each wavelength of light in the range from 400 nm to 700 nm... Traditional aperture structures may have a low reflectance at certain wavelengths (e.g., 550 nm) with a narrow low reflection band
Data Source
AI summary
An aperture structure for a substrate for an optical device includes an optical cavity layer, a light absorbing layer, and a blocking layer. The optical cavity layer includes a dielectric material and is characterized by a refractive index of about 1.4 or greater, as measured at a wavelength of 550 nm. The light absorbing layer includes a metal or a metal alloy and is characterized by an extinction coefficient k of at least 1, as measured at a wavelength of 550 nm. The blocking layer includes a metal or a metal alloy and is characterized by an optical density of at least 3 at each wavelength of light in the range from 400 nm to 700 nm. The aperture structure includes a reflectance of less than 5% at each wavelength of light in the range from 400 nm to 700 nm, as measured through the substrate.