Angle-Insensitive Multi-Wavelength Filter for Aviation Laser Protection
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Solution Overview
Problem
Conventional optical filters used in aviation applications are highly sensitive to incidence angles and can interfere with normal pilot vision, posing a hazard from high-power laser pointers, especially during mission-critical phases like takeoff and landing.
Innovation Solution
A laminate film with a flexible substrate, Bragg-reflector stacks, and a high-refractive-index layer is applied to aircraft cockpit windows, reducing angle sensitivity and allowing for effective blocking of hazardous laser light across a wide range of incidence angles while maintaining a neutral hue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional optical filters are used to block laser light, then laser hazard protection is provided, but the filters are highly sensitive to incidence angles and interfere with normal pilot vision
Solution Approach 1:
The optical filter is segmented into multiple functional layers: a substrate, multiple Bragg-reflector stacks with different stopping bands, and a high-refractive-index layer. Each layer serves a specific function - the Bragg-reflector stacks target specific laser wavelengths while the high-refractive-index layer reduces angle sensitivity, collectively solving both protection and adaptability requirements
Solution Approach 2:
The filter uses composite material structure combining different dielectric materials with alternating refractive indices in the Bragg-reflector stacks, and a high-refractive-index material layer on top. This composite structure enables both wavelength-selective filtering and angle-insensitivity, resolving the contradiction between targeted laser blocking and broad angular adaptability
2Object-affected harmful factors
If conventional optical filters are used to block laser light, then laser hazard protection is provided, but pilot vision is interfered with due to hue distortion
Solution Approach 1:
The filter applies local quality by designing each Bragg-reflector stack with specific stopping bands tailored to common laser wavelengths (532nm, 450nm, 405nm), while the overall composition of multiple stacks and the high-refractive-index layer collectively maintains neutral color transmission in the visible spectrum, thus providing targeted protection without compromising general vision quality
3Object-affected harmful factors
If laser-safety goggles are required for pilot protection, then laser hazard protection is provided, but pilot comfort and operational convenience are reduced
Solution Approach 1:
The optical filter is applied directly to the cockpit window surface in advance, providing permanent laser protection integrated into the aircraft structure. This preliminary action eliminates the need for pilots to put on and take off protective goggles during operations, thereby maintaining both protection and operational convenience
Solution Approach 2:
The optical filter serves multiple functions simultaneously: it blocks hazardous laser wavelengths, maintains neutral color transmission for normal vision, and is integrated into the window structure for permanent protection. This multi-functionality replaces the single-function goggle system, improving operational convenience while maintaining protection
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 solution provides effective angle-insensitive optical filtering that blocks hazardous laser light from 0° to 75° incidence, ensuring pilot safety without interfering with normal vision and reducing the need for cumbersome laser-safety goggles.
Implementation Method 1
A respective Bragg-reflector stack has a number of layers with alternating refractive indices, and the Bragg-reflector is configured to have a stopping band with a predetermined center wavelength which lies in the visible spectrum
Implementation Method 2
A refractive index of the high-refractive-index layer is greater than that of an adjacent layer of the one or more Bragg-reflector stacks, thereby reducing incident-angle sensitivity of the one or more Bragg-reflector stacks
Data Source
Figure 1
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Figure 2B
AI summary
One embodiment can provide a laminate film for optical filtering. The laminate film can include a flexible substrate, one or more Bragg-reflector stacks positioned on the flexible substrate, and a high-refractive-index layer positioned on the one or more Bragg-reflector stacks. A respective Bragg-reflector stack has a number of layers with alternating refractive indices, and the Bragg-reflector is configured to have a stopping band with a predetermined center wavelength. A refractive index of the high-refractive-index layer is greater than that of an adjacent layer of the one or more Bragg-reflector stacks, thereby reducing incident-angle sensitivity of the one or more Bragg-reflector stacks. Moreover, at least one Bragg-reflector stack is configured to achieve a predetermined hue.