Wavelength Conversion Element Scattering Layer Rayleigh
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Solution Overview
Problem
Existing wavelength conversion elements in projectors suffer from light loss due to reflective surfaces made of metals like silver, which absorb light and deteriorate under high intensity, limiting the increase in reflected fluorescence.
Innovation Solution
A wavelength conversion element with a scattering layer containing particles smaller than the wavelength of fluorescence, promoting Rayleigh scattering to reduce light loss and increase reflected fluorescence intensity, and a reflective layer with improved flatness to minimize additional light loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a reflective surface made of metal (silver, aluminum) is used, then high reflectance is obtained, but light is absorbed causing light loss of 3-5% and the metal deteriorates with heat generated by light absorption
Solution Approach 1:
A dielectric layer is introduced as an intermediary between the metal reflective surface and the incident light. This dielectric layer acts as a protective mediator that reduces direct light absorption by the metal while maintaining high reflectance, thereby reducing light loss and preventing metal deterioration from heat generation.
Solution Approach 2:
The reflective surface is transformed from a simple metal layer into a composite structure combining metal and dielectric materials. This composite reflective layer leverages the high reflectance of metal while the dielectric component reduces light absorption and heat generation, solving the contradiction between high reflectance and light loss.
2Illumination intensity
If the particle diameter of scattering layer particles is made small, then Rayleigh scattering dominates providing high backward scattering intensity, but the scattering effect becomes wavelength-dependent and may reduce overall scattering efficiency
Solution Approach 1:
The particle diameter is precisely controlled to be in the range of 0.01-10 μm, optimized to dominate Rayleigh scattering for the specific fluorescence wavelength range. This parameter optimization ensures high backward scattering intensity while maintaining effectiveness across the relevant wavelength spectrum.
Solution Approach 2:
The scattering layer uses particles with specific local properties (size, material composition) tailored to the fluorescence characteristics. By selecting particles with appropriate diameter and material properties, the scattering effect is localized to be most effective for the target wavelength range while minimizing unwanted wavelength dependence.
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 configuration enhances the intensity of fluorescence by reducing light loss at the reflective layer, allowing for higher luminance in projection images.
Implementation Method 1
the particle diameter of the particle contained in the scattering layer is smaller than the wavelength of the fluorescence, and therefore, a mode when the fluorescence is scattered by the scattering layer can be made into one in which Rayleigh scattering dominates. In Rayleigh scattering, the backward scattering intensity of light is high
Implementation Method 2
fluorescence is generated by irradiating the wavelength conversion element with excitation light emitted from the excitation light source such as a semiconductor laser or a light emitting diode
Implementation Method 3
a reflective layer provided to face the scattering layer and reflecting the excitation light or the fluorescence
Data Source
AI summary
A wavelength conversion element includes: a wavelength conversion layer including a first surface on which excitation light is incident, and a second surface opposed to the first surface; a scattering layer provided to face the second surface, containing a plurality of particles, and at least scattering fluorescence obtained by wavelength-converting the excitation light by the wavelength conversion layer; and a reflective layer provided to face the scattering layer and reflecting the excitation light or the fluorescence. The particle diameter of the particle is smaller than the wavelength of the fluorescence.