Optical Waveguide Light Extraction Features for Asymmetric Illumination
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Solution Overview
Problem
Low-efficiency light coupling and uneven illumination patterns in LED-based luminaires due to the inherent Lambertian emission of LEDs into narrow waveguide edges, leading to reduced light extraction and inefficient light distribution.
Innovation Solution
An optical waveguide body with specifically designed light extraction features, including linear and nonlinear shapes, and a light coupling cavity, which directs light asymmetrically to enhance light distribution and extraction efficiency, utilizing a combination of refractive and reflective surfaces to control light flow and emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If light is coupled into narrow waveguide edges from LED sources, then the waveguide structure is compact, but light extraction efficiency is reduced
Solution Approach 1:
The waveguide features localized extraction features (prisms, gratings, or textured surfaces) at specific positions along its length, creating regions with different optical properties. These local modifications enable targeted light extraction from the narrow waveguide edge without requiring the entire waveguide structure to be larger or less compact.
Solution Approach 2:
The patent introduces intermediate optical elements such as coupling lenses or optical adhesives between the LED source and the narrow waveguide edge. These intermediaries facilitate efficient light transfer into the constrained geometry of the narrow waveguide, enabling compact design while maintaining coupling efficiency.
2Ease of manufacture
If conventional symmetric extraction features are used, then manufacturing is simplified, but illumination uniformity deteriorates
Solution Approach 1:
The patent employs asymmetric extraction feature geometries where the prism angles, grating periods, or surface textures vary along the waveguide length or across different faces. This asymmetry enables compensation for the non-uniform light distribution that naturally occurs in waveguides, achieving uniform illumination while maintaining manufacturability through standard molding or fabrication processes.
Solution Approach 2:
The extraction features are divided into multiple segments or zones along the waveguide, with each segment having optimized geometric parameters. This segmentation allows different regions to address specific illumination requirements, achieving overall uniformity while using manufacturable discrete features rather than complex continuous variations.
3Loss of energy
If discrete coupling optics are used for each LED source, then light coupling efficiency is improved, but device complexity increases
Solution Approach 1:
The patent integrates multiple coupling functions into a single monolithic waveguide structure. The coupling surfaces, distribution channels, and extraction features are combined into one molded or machined component, eliminating the need for discrete coupling optics for each LED while maintaining high coupling efficiency through optimized integrated optical pathways.
Solution Approach 2:
The waveguide structure is designed to perform multiple functions simultaneously: it acts as a coupling element for multiple LED sources, a distribution medium for light transport, and an extraction system for uniform illumination. This multi-functionality reduces the total component count while maintaining the optical performance benefits of discrete coupling optics.
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 improved light extraction efficiency and asymmetric light distribution, reducing glare and enhancing illumination patterns, particularly suitable for applications like roadway lighting, while maintaining a compact form factor and high optical efficiency.
Implementation Method 1
Discrete coupling optics use refraction, total internal reflection, and surface or volume scattering to control the distribution of light injected into the waveguide.
Implementation Method 2
Discrete coupling optics use refraction, total internal reflection, and surface or volume scattering to control the distribution of light injected into the waveguide.
Data Source
AI summary
An optical waveguide body includes first and second pluralities of light extraction features disposed on a first side of the waveguide body and adapted to direct light out of the waveguide body through a second side of the waveguide body opposite the first side. Each of the first plurality of light extraction features has a linear shape and each of the second plurality of light extraction features has at least one of a piecewise linear shape and a nonlinear shape. The piecewise linear shape comprises two adjacent planar surfaces with an angle therebetween of at least about 30 and at most about 180 degrees. The waveguide body further has a light coupling cavity.