LED Phosphor Illumination for Fluorescence Radiance
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Solution Overview
Problem
Current high brightness LED light sources fail to match the radiance of traditional arc lamps, particularly in the 540 nm to 630 nm spectral band, limiting their effectiveness for fluorescence imaging and analysis applications.
Innovation Solution
A method involving a light emitting diode (LED) and a phosphor layer, where the LED emits a first wavelength within the absorption band of the phosphor, and a laser optically pumps the phosphor to increase emission intensity in the green, yellow, and amber regions, enhancing the output in the 545 nm and 575 nm bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional arc lamps are used for illumination, then high radiance is achieved, but the system suffers from short lifetime, temporal variation of output power, high voltage operation, and use of mercury
Solution Approach 1:
The patent transitions from arc lamp technology to LED technology, fundamentally changing the illumination source parameters. LEDs operate at lower voltages, consume less power, have longer lifetimes, and eliminate mercury while maintaining sufficient radiance for fluorescence imaging applications
Solution Approach 2:
The patent replaces the mechanical/electrical arc lamp system with a solid-state LED system. This substitution eliminates the need for high voltage striking, reduces temporal variations in output, and provides more stable, reliable operation with extended lifetime
2Reliability
If conventional arc lamps are replaced with solid state LED light sources, then advantages such as improved lifetime and lower power consumption are achieved, but the output in the 540 nm to 630 nm spectral band is insufficient
Solution Approach 1:
The patent combines multiple LED types with different emission wavelengths (blue LED at 440-470 nm, cyan LED at 470-495 nm, green LED at 495-560 nm, yellow LED at 560-590 nm, and red LED at 620-750 nm) with a phosphor layer to create a composite light source that achieves high radiance across the entire visible spectrum, particularly in the previously deficient 540-630 nm range
Solution Approach 2:
The patent uses a composite structure consisting of multiple LED chips with different semiconductor materials (InGaN for blue/cyan, AlInGaP for yellow/red, AlInGaN for green) combined with a phosphor layer. This composite approach enables the system to overcome the limitations of individual LED types and achieve high radiance across all required wavelengths
3Adaptability or versatility
If white light LED is used with blue LED and Ce:YAG phosphor, then broadband illumination is achieved, but emission in the green/yellow/amber region (560 nm and 590 nm) is limited
Solution Approach 1:
The patent segments the broadband illumination task into multiple wavelength components, using separate LED chips for blue (440-470 nm), cyan (470-495 nm), green (495-560 nm), yellow (560-590 nm), and red (620-750 nm) regions. This segmentation allows each LED type to be optimized for its specific wavelength range, ensuring high radiance in all regions including the previously limited 560 nm and 590 nm bands
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 significantly increases the optical output in the 545 nm and 575 nm bands, achieving high radiance comparable to or exceeding that of traditional arc lamps, while providing a more compact and cost-effective solution for fluorescence imaging and analysis.
Implementation Method 1
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
concurrently optically pumping the phosphor layer with laser emission λ2 to increase emission intensity in the phosphor emission wavelength band ΔλPHOSPHOR
Data Source
AI summary
An illumination system includes a phosphor to emit light in a wavelength band ΔλPHOSPHOR, a second light source to emit light at a second wavelength λ2 within an absorption band of the phosphor, a third light source to emit light at a third wavelength λ3 and a fourth light source to emit light at a fourth wavelength λ4. A controller drives the second, third and fourth light sources. A first dichroic optical element: 1) directs light from the phosphor to an optical output of the system, 2) directs light from the third light source to the optical output, and 3) directs light from the fourth light source to the optical output. A second dichroic optical element: 1) directs light from the third light source to the first dichroic optical element, and 2) directs the light from the fourth light source to the first dichroic optical element.