Stacked Notch Optical Filter for Wide-Angle Hostile Light Protection
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Solution Overview
Problem
Conventional optical filters provide limited protection against hostile electromagnetic radiation due to restricted cone angles of incidence, which are not suitable for uncontrolled viewing geometries, such as when viewing from different angles or by multiple individuals.
Innovation Solution
An optical filter comprising multiple stacked notch filters with different wavelengths, allowing each filter to attenuate electromagnetic radiation at distinct angles of incidence, thereby expanding the protected cone angle and enabling protection for multiple observation angles without significant reduction in visible light transmission or coloration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a single notch filter is used to attenuate electromagnetic radiation, then protection is provided within a cone of incidence, but the protection angle is limited and viewing geometry must be well controlled
Solution Approach 1:
The optical filter is segmented into multiple layers, each containing a notch filter with different optical properties. The first layer has a first notch filter with a first center wavelength, and the second layer has a second notch filter with a second center wavelength. This segmentation allows each layer to handle different angles of incidence, collectively providing protection over a wider angular range without constraining viewing geometry.
Solution Approach 2:
The solution transitions from a single-layer filter handling one angle to a multi-layer stacked structure handling multiple angles. By adding the dimensional aspect of layer stacking, the system expands its functional range from a single cone of incidence to multiple overlapping cones, effectively widening the total protection angle while maintaining adaptability to different viewing geometries.
2Object-affected harmful factors
If the bandwidth of the notch is increased to protect a larger cone angle, then protection angle increases, but visible light transmission and coloration are affected
Solution Approach 1:
Instead of broadening a single notch filter's bandwidth (which would affect visible light transmission), the protection function is segmented across multiple narrow-band notch filters. Each filter maintains a narrow bandwidth to preserve visible light transmission, but collectively they cover a wider angular range by targeting different wavelengths that correspond to different incident angles.
Solution Approach 2:
The system changes the parameter of center wavelength between layers rather than changing the bandwidth parameter. The first notch filter has a first center wavelength optimized for certain angles, while the second notch filter has a second center wavelength optimized for different angles. This parameter change approach allows angular coverage expansion without compromising visible light transmission through bandwidth broadening.
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 stacked notch filters provide enhanced protection against hostile light across a larger cone angle, allowing relative movement and multiple-angle protection, while maintaining high visible light transmission and minimizing coloration, thus addressing the limitations of conventional filters.
Implementation Method 1
a first notch filter arranged to attenuate electromagnetic radiation having a first wavelength, incident normally thereupon; and a second notch filter arranged to attenuate electromagnetic radiation having a second wavelength incident normally thereupon
Data Source
AI summary
An optical filter includes a first layer including a first notch filter arranged to attenuate electromagnetic radiation having a first wavelength λ1 incident normally thereupon. The optical filter includes a second layer including a second notch filter arranged to attenuate electromagnetic radiation having a second wavelength λ2 incident normally thereupon. The first wavelength λ1 and the second wavelength λ2 are different. The second layer is stacked upon the first layer. In use, the first notch filter attenuates the electromagnetic radiation having a predetermined wavelength λ incident thereupon at a first angle of incidence θ1 and the second notch filter attenuates the electromagnetic radiation having the predetermined wavelength λ incident thereupon at a second angle of incidence θ2, wherein the first angle of incidence θ1 and the second angle of incidence θ2 are different.