Multi-Wavelength Illumination System Using Collimated LEDs and Dichroic Mirrors
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Solution Overview
Problem
Existing multi-wavelength light sources face challenges in coupling efficiency due to large emitting areas and Lambertian-type emission distribution of LEDs, particularly in certain wavelength regions, leading to excessive losses and insufficient power delivery in microscopy and endoscopy applications.
Innovation Solution
The proposed solution involves a multi-wavelength illumination system using a configuration of collimated LEDs and dichroic mirrors, where the LEDs are arranged to minimize transmission losses by using a stack of aspheric lenses and a linear waveguide dichroic mirror arrangement, allowing for improved optical efficiency and the addition of new wavelength channels with minimal impact on the system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple LEDs are used to provide multi-wavelength illumination, then the spectral coverage is improved, but the coupling efficiency into the fiber deteriorates due to large emitting areas and Lambertian emission distribution
Solution Approach 1:
The patent segments the illumination system into multiple independent LED sources, each emitting at a specific wavelength, rather than using a single broadband source. This segmentation allows optimization of each LED's emission characteristics while maintaining overall spectral coverage, and enables independent coupling optimization for each wavelength channel into the fiber.
Solution Approach 2:
The patent introduces optical intermediaries including aspheric lenses positioned close to each LED to collimate the Lambertian emission, and dichroic mirrors to combine multiple wavelength beams. These intermediary components transform the divergent LED emission into collimated beams that can be efficiently coupled into the fiber, mediating between the LED's emission characteristics and the fiber's coupling requirements.
2Power
If the LED emitting area is increased to provide sufficient power, then the illumination intensity is improved, but the coupling efficiency into the fiber deteriorates
Solution Approach 1:
The patent addresses the power-coupling efficiency tradeoff by transitioning from direct coupling in real space to coupling through Fourier space using lens systems. The aspheric lenses transform the spatial distribution of light from large emitting areas into collimated beams with controlled angular distribution, enabling efficient coupling into the fiber by matching the numerical aperture in a different spatial dimension.
Solution Approach 2:
The patent changes the optical parameters of the LED emission by introducing aspheric lenses that modify the beam divergence angle and spatial distribution. By adjusting the lens-LED distance and lens parameters, the system transforms the Lambertian emission pattern into a collimated beam with parameters optimized for fiber coupling, thereby maintaining high power while improving coupling efficiency.
3Device complexity
If traditional optical components are used to combine multiple LED beams, then the system complexity is reduced, but the optical throughput deteriorates due to excessive transmission losses
Solution Approach 1:
The patent merges multiple LED beams of different wavelengths into a single collimated output beam using a dichroic mirror arrangement. The dichroic mirrors are positioned and oriented to reflect specific wavelength ranges while transmitting others, combining all LED emissions into one beam path that maintains high optical throughput by minimizing the number of transmission interfaces and avoiding excessive component complexity.
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 configuration enhances optical throughput, increases the collection efficiency of LED emissions, and allows for a two-fold increase in total power coupled into the output light guide, while maintaining cost-effectiveness and simplicity in assembly.
Implementation Method 1
The LED light collection efficiency may be improved by using, for example, a stack of two aspheric lenses at relatively close distance to the LED emitting surface
Implementation Method 2
a plurality of reflective optical components oriented identically to one another, wherein the plurality of reflective optical components is configured to direct the first collimated beam, the second collimated beam, the third collimated beam, the fourth collimated beam, and the fifth collimated beam along a common axis
Data Source
AI summary
Methods and systems are provided for a light emitting device. In one example, an illumination system comprises a plurality of light sources, each light source of the plurality of light sources comprising a light emitting diode configured to emit a collimated beam of light of a color, a plurality of reflective optical components oriented identically to one another, wherein the plurality of reflective optical components is configured to direct the first collimated beam, the second collimated beam, the third collimated beam, the fourth collimated beam, and the fifth collimated beam along a common axis, and an output positioned to receive light along the common axis, wherein the output is configured to generate an output beam.