Multimode Waveguide Light Source for High Radiance Uniformity
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Solution Overview
Problem
Conventional light sources face a tradeoff between achieving high radiance and uniformity, with methods like temporal averaging being time-consuming and inefficient, while thermal sources lack sufficient radiance due to their large bandwidth.
Innovation Solution
A system and method utilizing a spectral light source and a multimode waveguide with a light scattering medium to achieve high radiance and low spatial coherence without temporal averaging, by effecting multiple scattering events and judiciously selecting the spectral line shape and optical path difference distribution to ensure incoherent light generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If laser devices are used to achieve high radiance, then radiance is improved, but uniformity deteriorates due to coherent interference patterns
Solution Approach 1:
The invention segments the coherent laser beam into multiple independent spatial modes by coupling it into a multimode waveguide. Each mode propagates independently with different optical path lengths, causing the coherent interference patterns to average out and produce uniform incoherent-like illumination while preserving high radiance
Solution Approach 2:
The invention transitions from temporal averaging (one dimension) to spatial mode multiplexing (another dimension). By distributing light across multiple spatial modes in the waveguide, the system achieves uniformity through spatial diversity rather than temporal scanning, eliminating the need for moving parts while maintaining high radiance
2Stability of the object's composition
If thermal light sources are used to achieve uniform illumination, then uniformity is improved, but radiance deteriorates due to large bandwidth
Solution Approach 1:
The invention changes the spectral parameter by using a narrow-band laser source instead of a broad-band thermal source. The laser's narrow spectral linewidth is then transformed into effective broadening through the waveguide's modal dispersion, achieving both high radiance (from the laser) and uniformity (from the modal mixing) simultaneously
3Stability of the object's composition
If temporal averaging techniques are used to reduce non-uniformity, then uniformity is improved, but productivity deteriorates due to time-consuming scanning
Solution Approach 1:
The invention replaces the mechanical scanning system (moving mirrors or diffusers) with a static multimode waveguide structure. The uniformity that previously required temporal averaging through mechanical motion is achieved instantaneously through the spatial distribution of multiple propagating modes, eliminating moving parts and enabling high-speed applications
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
This approach allows for high uniformity and high radiance at any instantaneous moment, eliminating the need for time-consuming averaging techniques and maintaining high radiance while improving illumination uniformity.
Implementation Method 1
a light scattering medium, wherein the light scattering medium is selected to scatter light propagating in the waveguide
Implementation Method 2
a multimode waveguide, characterized by an optical path difference distribution described by a standard deviation
Data Source
AI summary
A system for generating light, comprises a spectral light source, characterized by a spectral line shape described by a visibility function; and a multimode waveguide, characterized by an optical path difference distribution described by a standard deviation. The standard deviation typically matches, within a predetermined tolerance, a location of a zero point of the visibility function at which a contrast of the visibility function is less than 0.1.