Laser White Light Source Low Etendue Design
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Solution Overview
Problem
Existing white light sources, particularly those using thermal sources and conversion layers, suffer from high etendue, leading to inefficient light transmission and increased energy consumption, as well as reduced service life due to unwanted heat dissipation and scattering, which degrades beam quality and limits their application in compact and efficient lighting systems.
Innovation Solution
A device utilizing a monochromatic laser light source emitting in the blue or ultraviolet range, focused onto a conversion medium with downstream optics that reduce the opening angle of converted light, combined with a reflection mechanism to minimize etendue and enhance beam quality, allowing for the generation of white light with low etendue and high luminous flux.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If thermal light sources are used to generate white light, then high luminous flux can be achieved, but a large amount of unwanted waste heat is emitted and complex heat dissipation is required
Solution Approach 1:
The invention changes the fundamental operating parameters from thermal radiation to laser excitation. A laser light source operates at a specific wavelength to excite phosphor materials, which then emit broad-spectrum visible light. This parameter change eliminates the need for complex heat dissipation systems while maintaining high luminous flux output.
Solution Approach 2:
The invention replaces the thermal radiation mechanism with a photoluminescence mechanism. Instead of heating a filament or lamp to generate white light through thermal radiation, a laser excites phosphor materials that convert the monochromatic light into broad-spectrum visible light, eliminating waste heat generation.
2Loss of energy
If conversion layers are used with LED or laser light sources, then white light can be generated with lower heat, but the etendue increases due to scattering in the conversion medium
Solution Approach 1:
The invention performs preliminary focusing of the laser beam to a small spot size before the light enters the phosphor conversion medium. This preliminary action minimizes the initial etendue, and by using total internal reflection at the phosphor-air interface, the converted light is redirected back through the same small area, preventing etendue expansion.
Solution Approach 2:
The invention introduces an optical interface (phosphor-air boundary) as an intermediary that enables total internal reflection. This intermediary mechanism redirects the converted light back through the original small input area, acting as a mediator that prevents etendue increase while maintaining efficient light conversion.
3Illumination intensity
If light is scattered in the conversion medium to adapt to emission characteristics, then white light can be generated, but the etendue of the light source is increased
Solution Approach 1:
The invention changes the geometric parameters of light propagation by utilizing total internal reflection at the phosphor-air interface. Instead of allowing light to scatter freely in all directions, the optical interface redirects light back through the original small input area, fundamentally changing the spatial distribution parameters and maintaining low etendue.
Solution Approach 2:
The invention exploits the optical dimension by creating a high-reflection interface at the phosphor-air boundary. Light that would normally scatter in three dimensions is redirected back through the original path, effectively using optical dimensionality to constrain the light propagation and maintain low etendue while still achieving broad-spectrum white light generation.
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 solution effectively reduces the etendue of the white light source, improving beam quality and enabling efficient coupling of light into small areas or fiber bundles with minimal energy loss, thus enhancing the performance and longevity of lighting systems.
Implementation Method 1
at least one monochromatic light source emitting in the blue and/or ultraviolet spectral range, the light of the at least one monochromatic light source being generated by a laser
Implementation Method 2
the light from the at least one monochromatic light source is focused by an optical system onto the conversion medium
Implementation Method 3
the conversion medium at least partially converts the monochromatic light irradiated into another spectral range
Implementation Method 4
optics downstream of the conversion medium in the direction of light propagation, which reduce the opening angle of the converted light emanating from the focus
Implementation Method 5
a reflection device is arranged on the opposite side of the conversion medium, which reflects the light from the light source and the light converted in the conversion medium back through the conversion medium
Data Source
Figure 1a~1b
Figure 1c~2
Figure 3
AI summary
The invention relates to a device for generating white light (1) comprising at least one light source (10) and at least one conversion medium (40), wherein the at least one light source (10) emits light in the blue and/or ultraviolet spectral range and the light of the at least one light source (10) is generated by a laser and the light of the at least one light source is focussed by an optical system (30) onto the conversion medium (40) and the conversion medium (40) converts the incident light (20) at least proportionately into a different spectral range (60).