Narrowband Reflector for Laser Light Conversion
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Solution Overview
Problem
The reliability of light converters in laser-based light sources, such as automotive headlights, is compromised by ineffective thermal and optical coupling with heatsinks, leading to overheating and premature degradation due to intense blue light exposure, which causes optical losses and reduces efficiency.
Innovation Solution
A light conversion device with a narrowband reflective structure is implemented to reflect at least 55% of primary light, reducing its intensity on the heatsink and coupling layer, thereby preventing degradation and ensuring effective thermal and optical coupling between the light converter and heatsink, using a ceramic light converter with a dichroic coating and a dielectric mirror to manage light reflection and transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a silver mirror structure is used to reflect converted light and avoid optical losses, then optical efficiency is improved, but the intense blue light causes degradation of the mirror and glue layer over time
Solution Approach 1:
The reflective system is segmented into two distinct functional layers: a narrowband reflector layer that reflects primary blue light while transmitting converted light, and a silver mirror layer that reflects all wavelengths. This segmentation allows each layer to perform its specific function without the silver mirror being exposed to degrading blue light intensities.
Solution Approach 2:
The narrowband reflector acts as an intermediary protective layer between the intense blue laser light and the silver mirror structure. It selectively reflects the harmful blue wavelengths before they can reach and degrade the silver mirror and glue layer, while still allowing the converted yellow light to pass through to the mirror for reflection.
2Temperature
If the light converter is directly coupled to the heatsink for effective thermal dissipation, then temperature control is improved, but the coupling layer degrades due to intense blue light and high temperature
Solution Approach 1:
The narrowband reflector serves as a protective intermediary layer positioned between the intense blue laser light and the coupling layer. It reflects the harmful blue wavelengths before they can penetrate and degrade the coupling material, while allowing thermal energy to conduct through to the heatsink for effective temperature control.
Solution Approach 2:
The coupling layer is designed with specific local properties: it is made from temperature-stable silicone materials optimized for thermal conduction while being positioned in a region where the narrowband reflector protects it from the most intense blue light exposure, creating a localized protective environment.
3Reliability
If a narrowband reflective structure is added to protect against blue light degradation, then reliability is improved, but device complexity increases
Solution Approach 1:
The narrowband reflector is designed to perform multiple functions simultaneously: it reflects primary blue light to protect underlying layers, transmits converted yellow light to the mirror for reflection, and provides thermal conduction path to the heatsink. This multi-functionality reduces the need for additional separate protective components.
Solution Approach 2:
The narrowband reflector is implemented as a dielectric coating or multilayer composite structure deposited on the heatsink or coupling layer. This composite approach integrates the protective function into the existing thermal management structure rather than adding a separate component, thereby minimizing overall device complexity.
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 delays or inhibits optical degradation, maintaining the performance and longevity of the light conversion device by reducing the intensity of primary light on sensitive components, ensuring reliable thermal dissipation and maintaining optical efficiency.
Implementation Method 1
The reflective structure is a narrowband reflector which is arranged to reflect at least 55%, more preferably at least 70% and most preferably at least 90% of the primary light impinging on the reflective structure
Implementation Method 2
The light converter is adapted to convert primary light to converted light. A peak emission wavelength of the converted light is in a longer wavelength range than a peak emission wavelength of the primary light
Implementation Method 3
It is therefore necessary to enable a reliable and effective thermal coupling between the light converter (e.g. phosphor) and a heat dissipating structure (heatsink)
Data Source
AI summary
The invention describes a light conversion device having a light converter, which is adapted to convert primary light to converted light, so that a peak emission wavelength of the converted light is in a longer wavelength range than a peak emission wavelength of the primary light. The light conversion device also has a reflective structure coupled to at least a part of a coupling surface of the light converter, where the reflective structure is a narrowband reflector arranged to reflect at least some of the primary light impinging on the reflective structure and to transmit at least some of the converted light impinging on the reflective structure.