Wavelength Conversion Element Refractive Index Interface
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Solution Overview
Problem
Existing light source apparatuses face challenges in achieving high-intensity fluorescence due to difficulties in heat dissipation and reflectance issues with phosphor layers, particularly with silver reflection surfaces that suffer from reflection loss and thermal degradation.
Innovation Solution
A wavelength conversion element is designed with a refractive index interface between the phosphor layer and the reflection section, utilizing a dielectric multilayer film and a prism structure to narrow the angular distribution of fluorescence, increasing reflectance and heat dissipation, and incorporating a substrate with high thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a silver reflection surface is used to increase reflectance, then high reflectance is achieved, but reflection loss occurs and thermal oxidation degrades the silver
Solution Approach 1:
The patent changes the material parameter of the reflection surface from silver to a dielectric multilayer film with optimized refractive indices and thicknesses. This parameter change eliminates reflection loss and thermal oxidation while achieving high reflectance through constructive interference of light waves in the dielectric layers.
Solution Approach 2:
The patent uses a composite dielectric multilayer film structure consisting of multiple layers with different refractive indices (e.g., TiO2, SiO2, Nb2O5) deposited on the phosphor layer. This composite structure provides high reflectance through optical interference while being thermally stable and free from oxidation issues.
2Illumination intensity
If a transmissive wavelength conversion element is used to improve fluorescence orientation directivity, then directivity is improved, but heat dissipation becomes difficult
Solution Approach 1:
Instead of using a transmissive structure where light passes through the phosphor layer, the patent inverts the approach by using a reflective structure where the phosphor layer is positioned on top of a high-reflectance dielectric mirror. This causes fluorescence to be reflected back through the phosphor layer, improving directionality while the substrate beneath provides heat dissipation.
3Illumination intensity
If the reflectance at the reflection surface is increased to increase reflected fluorescence amount, then high-optical-intensity fluorescence is achieved, but silver absorbs light and generates heat causing degradation
Solution Approach 1:
The patent replaces the expensive and degradable silver reflection surface with a dielectric multilayer film that is thermally stable and does not oxidize. The dielectric layers act as a durable, maintenance-free alternative that maintains high reflectance without absorbing light and generating heat.
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 enhances reflectance and heat dissipation, enabling the production of high-optical-intensity fluorescence and maintaining stable optical performance, overcoming the limitations of previous technologies.
Implementation Method 1
a refractive index interface which is provided between the first surface and the reflection surface and where a first medium and a second medium having refractive indices different from each other are in contact with each other. The refractive index of the first medium located on the first-surface-side of the refractive index interface is higher than the refractive index of the second medium located on the reflection-surface-side of the refractive index interface, and regarding the fluorescence traveling from the wavelength conversion section toward the reflection section, an angular distribution of the fluorescence having passed through the refractive index interface is narrower than the angular distribution of the fluorescence before passing through the refractive index interface
Implementation Method 2
a reflection section having a reflection surface that reflects the fluorescence
Implementation Method 3
the wavelength conversion element is irradiated with excitation light emitted from the excitation light source, such as a semiconductor laser or a light emitting diode, to produce fluorescence
Implementation Method 4
a wavelength conversion section having a first surface on which excitation light is incident and through which fluorescence exits
Implementation Method 5
incorporating a substrate with high thermal conductivity
Data Source
AI summary
A wavelength conversion element according to an aspect of the invention includes a wavelength conversion section having a first surface, a reflection section having a reflection surface that reflects the fluorescence, a light-transparent bonding section that bonds the wavelength conversion section to the reflection section, and a refractive index interface which is provided between the first surface and the reflection surface and where a first medium and a second medium having refractive indices different from each other are in contact with each other. The refractive index of the first medium is higher than the refractive index of the second medium, and regarding the fluorescence traveling from the wavelength conversion section toward the reflection section, the angular distribution of the fluorescence having passed through the refractive index interface is narrower than the angular distribution of the fluorescence before passing through the refractive index interface.