Alternating Dielectric Optical Filter for NIR Detection
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Solution Overview
Problem
Ambient light interferes with near-infrared (NIR) light in optical systems, reducing the accuracy of three-dimensional image generation and gesture recognition by optical receivers.
Innovation Solution
An optical filter comprising a set of dielectric thin film layers with alternating high and low refractive index materials, including hydrogenated silicon and other materials, is used to block ambient light and pass NIR light, minimizing interference and maintaining image accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an optical filter with multiple dielectric layers is used to block ambient light, then the accuracy of NIR light detection is improved, but the device complexity increases
Solution Approach 1:
The optical filter is segmented into multiple dielectric layers with alternating high and low refractive indices. Each layer contributes to the overall filtering function, with specific thicknesses designed to create constructive and destructive interference patterns that selectively block ambient light while transmitting NIR light wavelengths.
Solution Approach 2:
The optical filter employs composite material structure combining different dielectric materials with contrasting refractive indices. This composite approach enables enhanced optical selectivity and filtering performance that cannot be achieved with a single material, allowing precise control over the transmission and reflection characteristics across different wavelengths.
2Object-affected harmful factors
If multiple subsets of optical filter layers with different materials are used, then the filtering effectiveness against ambient light is improved, but the manufacturing precision requirements increase
Solution Approach 1:
Different subsets of optical filter layers are designed with locally optimized material compositions and thicknesses tailored to specific wavelength ranges. The first subset targets certain ambient light wavelengths, the second subset addresses other wavelengths, and the third subset fine-tunes the NIR transmission, allowing each layer to perform its specialized filtering function with optimized local properties.
Solution Approach 2:
The optical filter design utilizes parameter changes in material refractive indices and layer thicknesses to achieve different filtering effects. By varying these parameters across the three subsets, the filter creates distinct interference patterns that collectively block broad-spectrum ambient light while maintaining NIR transmission, with each subset optimized for specific parameter ranges.
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 effectively filters out ambient light, enhancing the accuracy of three-dimensional image generation and gesture recognition by reducing the intensity of ambient light interference.
Implementation Method 1
An optical filter may include a set of optical filter layers, the set of optical filter layers including: a first subset of optical filter layers comprising a first material with a first refractive index... a second subset of optical filter layers comprising a second material with a second refractive index... the second refractive index being less than the first refractive index
Data Source
AI summary
An optical filter may include a set of optical filter layers disposed onto a substrate. The set of optical filter layers may include a first subset of optical filter layers comprising a first material with a first refractive index. The first material may comprise at least silicon and hydrogen. The set of optical filter layers may include a second subset of optical filter layers comprising a second material with a second refractive index. The second material is different from the first material and the second refractive index is less than the first refractive index. The set of optical filter layers may include a third subset of optical filter layers comprising a third material different from the first material and the second material.