LED-Phosphor Laser Pumping for Fluorescence Imaging
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Solution Overview
Problem
Conventional high radiance illumination sources, such as mercury lamps, are limited by short lifetime, environmental hazards, and insufficient brightness in specific wavelength ranges like 540 nm to 630 nm, which is challenging for fluorescence imaging and analysis applications.
Innovation Solution
A high brightness illumination system combining a light emitting diode (LED) with a phosphor layer and a laser for concurrent optical pumping, enhancing emission intensity in the green/yellow/amber regions by using a dichroic element to couple the laser emission with the LED and phosphor output along a common optical axis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional arc lamps (mercury, metal halide, xenon) are used for illumination, then high radiance is achieved, but lifetime is short and environmental hazards occur
Solution Approach 1:
The patent replaces conventional arc lamp technology with solid-state LED technology, substituting a mechanical/electrical arc discharge system with a semiconductor-based electroluminescence system. This substitution achieves comparable or superior radiance while eliminating the short lifetime and environmental hazards associated with arc lamps, as LEDs have no filament or arc tube that can fail.
2Illumination intensity
If conventional arc lamps are used for illumination, then high radiance is achieved, but environmental hazards occur due to mercury use
Solution Approach 1:
The patent eliminates mercury-containing arc lamp technology in favor of mercury-free solid-state LED technology. This substitution removes the environmental hazard entirely while maintaining or improving illumination performance, as LEDs use semiconductor materials that do not contain toxic heavy metals like mercury.
3Reliability
If high power LEDs are used to replace arc lamps, then lifetime is improved and environmental impact is reduced, but brightness in the 540 nm to 630 nm spectral band is insufficient
Solution Approach 1:
The patent combines multiple LED types with different emission characteristics (including those that emit in the blue and UV ranges) with phosphor conversion materials to generate the missing green/yellow/amber wavelengths. This merging of multiple light generation mechanisms compensates for the individual limitations of each component and achieves full spectral coverage with high brightness in previously deficient regions.
Solution Approach 2:
The patent introduces phosphor materials as intermediary components that convert light from LEDs (particularly blue and UV LEDs) into the desired green/yellow/amber wavelengths. The phosphor acts as a mediator that transforms the spectral output, filling the 'green gap' and enabling high brightness in the 540-630 nm range without requiring direct emission from the LED itself.
4Illumination intensity
If arc lamps are used for fluorescence imaging, then sufficient brightness at specific wavelengths (545 nm, 575 nm) is achieved, but voltage operation requires kilovolts
Solution Approach 1:
The patent replaces the high-voltage arc discharge mechanism with low-voltage solid-state LED operation. LEDs typically operate at voltages of a few volts rather than the kilovolts required for arc lamps, dramatically reducing the electrical energy requirements while maintaining sufficient brightness at the required wavelengths through the combination of direct LED emission and phosphor conversion.
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 system achieves high radiance output at wavelengths like 545 nm and 575 nm, matching or exceeding traditional arc lamp performance while offering lower voltage operation, longer lifetime, and reduced environmental impact.
Implementation Method 1
providing a first light source comprising a light emitting device (LED) and a phosphor layer, the LED emitting a first wavelength λ1 within an absorption band of the phosphor layer
Implementation Method 2
the phosphor layer emitting broadband light emission of longer wavelength comprising light in a wavelength band ΔλPHOSPHOR
Implementation Method 3
providing a second light source comprising a laser emitting a second wavelength λ2, within the absorption band of the phosphor layer; and while operating the LED to generate emission at λ1 and ΔλPHOSPHOR, concurrently optically pumping the phosphor layer with laser emission λ2 to increase emission intensity in the phosphor emission wavelength band ΔλPHOSPHOR
Implementation Method 4
using a dichroic element to couple the laser emission with the LED and phosphor output along a common optical axis
Data Source
AI summary
A solid state illumination system is disclosed, wherein a light source module comprises a first light source, comprising an LED and a phosphor layer, the LED emitting a wavelength λ1 in an absorption band of the phosphor layer for generating longer wavelength broadband light emission from the phosphor, ΔλPHOSPHOR, and a second light source comprising a laser emitting a wavelength λ2 in the absorption band of the phosphor layer. While operating the LED, concurrent laser pumping of the phosphor layer increases the light emission of the phosphor, and provides high brightness emission, e.g. in green, yellow or amber spectral regions. Additional modules, which provide emission at other wavelengths, e.g. in the UV and near UV spectral bands, together with dichroic beam-splitters/combiners allow for an efficient, compact, high-brightness illumination system, suitable for fluorescence imaging and analysis.