Optical Angular Filter Pillar-Wall Refraction Index Ratio
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Solution Overview
Problem
Existing optical angular filters are inadequate in effectively filtering radiation based on incidence angle and wavelength, leading to suboptimal performance in biometric imaging systems.
Innovation Solution
An optical angular filter comprising a network of pillars made of a first transparent material and an array of walls made of a second opaque material, where the ratio of their refraction indices changes with wavelength, allowing for selective transmission and reflection of radiation based on incidence angle and wavelength, optimized by using organic resins with specific refraction index ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional angular filters are used, then the basic filtering function is provided, but the selectivity and efficiency are insufficient
Solution Approach 1:
The patent employs a composite structure combining transparent pillars made of first material with opaque walls made of second material. The selective transmission and reflection properties are achieved through the interaction of these different materials, where the refraction index ratio between them creates wavelength-dependent optical response, thereby enhancing filtering selectivity and efficiency
Solution Approach 2:
The patent utilizes the wavelength-dependent refraction index ratio between the two materials to achieve selective transmission. By changing the optical parameters (refraction indices) based on wavelength, the filter achieves different transmission characteristics for different wavelengths, improving both selectivity and filtering efficiency
2Ease of manufacture
If the filter uses materials with constant refraction indices, then the structure is simple, but the wavelength-selective transmission is limited
Solution Approach 1:
The patent selects materials whose refraction indices are not constant but vary with wavelength. This parameter change allows the filter to achieve different transmission characteristics at different wavelengths, enabling wavelength-selective filtering while maintaining a relatively simple pillar-and-wall structure
Solution Approach 2:
By combining two materials with different refraction index characteristics, the patent creates a composite structure that inherently provides wavelength-dependent response. The interaction between the transparent pillar material and opaque wall material, through their refraction index ratio, enables adaptive wavelength response without complex additional 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 solution enhances the selectivity and efficiency of the angular filter, widening the transmission peak and optimizing the filter's response to incidence angles and wavelengths, effectively filtering infrared radiation while favoring visible light, thus improving the performance of biometric imaging systems.
Implementation Method 1
the ratio between the refraction indexes of the first and second materials depending on the wavelength
Data Source
AI summary
An optical angular filter includes a network of pillars made of a first transparent material, and an array of walls made of a second opaque material, separating the pillars from one another. The refraction index of the second material is different from that of the first material.