Planar Waveguide Diffraction Gratings for Uniform Light Extraction
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Solution Overview
Problem
Existing lens-free optical imaging systems face challenges in manufacturing complexity and uneven light distribution due to the need for multiple secondary waveguides and angled facets, which complicates the production process and results in inadequate illumination of the sample.
Innovation Solution
A light distributing device using a planar waveguide with two cladding layers and a core layer, incorporating a set of diffraction gratings that distribute light evenly over a large surface without increasing the device's thickness, allowing for easy integration into lens-free optical imaging systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple secondary waveguides and angled facets are used to distribute light, then light distribution capability is improved, but manufacturing complexity increases
Solution Approach 1:
The device segments the light distribution function into multiple diffraction gratings with varying fill factors, where each grating handles a specific portion of the light extraction. This allows complex light distribution to be achieved through simple, identical structural units rather than complex individual waveguides.
Solution Approach 2:
The invention changes the fill factor parameter of the diffraction gratings monotonically across the array to control light extraction. By varying this single parameter rather than changing the entire waveguide structure, the device achieves different light distribution characteristics with simple parameter adjustment instead of complex manufacturing.
2Use of energy by moving object
If multiple secondary waveguides are used to extract light, then light extraction efficiency is improved, but alignment constraints increase
Solution Approach 1:
The invention merges multiple light extraction functions into a single planar waveguide structure with multiple diffraction gratings. All gratings are fabricated on the same substrate plane, eliminating the need for complex three-dimensional alignment between separate waveguides while maintaining high light extraction efficiency through the array of gratings.
3Length of moving object
If a thin waveguide structure is used to maintain small thickness, then integration capability is improved, but light extraction capability deteriorates
Solution Approach 1:
The invention replaces traditional mechanical light extraction methods (such as angled facets requiring physical carving) with diffraction gratings that use optical interference effects. This allows efficient light extraction from thin waveguides through optical field manipulation rather than mechanical structural changes.
Solution Approach 2:
By changing the fill factor parameter of the diffraction gratings, the invention optimizes light extraction efficiency without changing the waveguide thickness. This parameter control allows the same thin waveguide structure to achieve high extraction efficiency through optical design rather than structural thickening.
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 device achieves even light distribution over a large surface with a thin profile, simplifying manufacturing and reducing alignment constraints while maintaining control over light extraction angles, thus enhancing the imaging system's efficiency and cost-effectiveness.
Implementation Method 1
an extraction set, located in the planar waveguide, and constituted by a plurality of diffraction gratings distributed in the two dimensions of a plane parallel to the plane of the planar waveguide
Implementation Method 2
a planar waveguide which comprises two cladding layers and one core layer... with the two cladding layers and the core layer being superposed together along an axis orthogonal to the plane of the planar waveguide
Data Source
AI summary
A light distributing device configured for, in use, distributing, over a scene to illuminate light rays that come from an auxiliary light source, and which comprises: a planar waveguide, with a core layer disposed between the two cladding layers; and an extraction set, located in the planar waveguide, and constituted by a plurality of diffraction gratings distributed in the two dimensions of a plane parallel to the plane of the planar waveguide.