Uniform Illumination Light Diffusing Fiber with Refractive Index Gradient
Solution Overview
Problem
Conventional light-diffusing optical fibers fail to provide uniform illumination over long distances due to wavelength-dependent scattering, leading to uneven light distribution.
Innovation Solution
A light-diffusing element comprising a glass core with a cladding of lower refractive index and a coating containing scattering centers, where the cladding thickness is optimized to manage Rayleigh scattering, ensuring uniform light diffusion across various wavelengths, and the coating further scatters light uniformly in all directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If conventional light-diffusing fibers use voids (bubbles or airlines) to scatter light, then light diffusion occurs over short distances, but uniform illumination cannot be maintained over long distances
Solution Approach 1:
The patent changes the refractive index parameter of the cladding layer to resolve the contradiction. Specifically, the cladding is designed with a refractive index lower than both the core and coating layers, creating a refractive index gradient (n_core > n_cladding < n_coating). This parameter change enables light to be scattered back into the core through the coating while maintaining total internal reflection at the core-cladding interface, allowing uniform illumination over long distances (30 meters or more) without compromising illumination uniformity.
2Loss of energy
If the cladding thickness is increased to reduce absorption losses, then transmission efficiency improves, but scattering uniformity across wavelengths may be compromised
Solution Approach 1:
The patent employs a composite multi-layer structure consisting of core, cladding, and coating layers with different refractive indices. The cladding layer with lower refractive index acts as an optical barrier to minimize absorption losses, while the outer coating layer with higher refractive index provides wavelength-independent scattering. This composite structure achieves both low energy loss and uniform scattering intensity across different wavelengths (440 nm to 2000 nm).
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 achieves uniform illumination over lengths of at least 30 meters with minimal absorption losses, maintaining consistent scattering intensity across different wavelengths, thereby providing broad-array illumination effectively.
Implementation Method 1
the cladding has a second refractive index that is less than the first refractive index of the glass core... ensuring uniform light diffusion across various wavelengths
Implementation Method 2
the coating includes first scattering centers... the coating further scatters light uniformly in all directions
Data Source
AI summary
Embodiments of the disclosure relates to a light-diffusing element. The light diffusing element includes a glass core having a first refractive index. The light diffusing element also includes a cladding surrounding the glass core. The cladding includes an inner cladding surface and an outer cladding surface. The inner cladding surface and the outer cladding surface define a cladding thickness of from 5 μm to 30 μm. The cladding has a second refractive index that is less than the first refractive index of the glass core. The light diffusing element also includes a coating surrounding the cladding. The coating has an inner coating surface and an outer coating surface. The inner coating surface contacts the outer cladding surface. The outer coating surface defines an outermost surface of the light-diffusing element, and the coating includes first scattering centers.