Illuminator Air Layer for Fluorescence Efficiency
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Solution Overview
Problem
Existing illuminators used in projectors suffer from decreased fluorescence utilization efficiency due to the reflection of fluorescence at large angles of incidence off the light incident surface of the pickup lens, leading to loss of light and reduced efficiency.
Innovation Solution
An illuminator design featuring a light source that emits first light, a wavelength converter that converts this light into second light, and an optical element with an air layer between them, where the air layer's length is between 0.3 μm and 9.0 μm, and the optical element has a coefficient of linear expansion less than 65×10−7/°C and thermal conductivity greater than 1.0 W/m·K, optimizing light transmission and heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the pickup lens is placed close to the wavelength converter to reduce reflection loss, then fluorescence utilization efficiency improves, but thermal stress and heat-induced damage to the optical element increase
Solution Approach 1:
An air layer is introduced as an intermediary between the wavelength converter and the pickup lens. This air layer acts as a thermal isolation barrier that prevents heat transfer to the optical element while maintaining optical functionality, thus protecting the lens from thermal damage without significantly compromising fluorescence collection efficiency
Solution Approach 2:
The air layer thickness is optimized within a specific range (0.3 μm to 9.0 μm) to balance two competing requirements: being thin enough to minimize reflection loss and maintain optical coupling, yet thick enough to provide adequate thermal isolation and prevent heat-induced damage to the optical element
2Temperature
If the optical element is made with high thermal conductivity to improve heat dissipation, then thermal stress decreases, but the coefficient of linear expansion must be reduced to minimize thermal stress
Solution Approach 1:
The optical element is selected with specific material parameters: a coefficient of linear expansion ≤65×10−7/°C and thermal conductivity ≥1.0 W/m·K. These parameter specifications ensure the material can effectively conduct heat away from the wavelength converter while expanding minimally under thermal stress, thus preventing both overheating and thermal stress damage
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 configuration reduces fluorescence loss and enhances light utilization efficiency by refracting and transmitting the fluorescence effectively, while minimizing thermal stress and heat-induced damage to the optical element.
Implementation Method 1
there has been a proposed illuminator using fluorescence emitted from a phosphor when the phosphor is irradiated with excitation light outputted from a light emitter
Implementation Method 2
An air layer is provided between the wavelength converter and the optical element... refracting and transmitting the fluorescence effectively
Data Source
AI summary
An illuminator includes a light source that emits first light that belongs to a first wavelength band, a wavelength converter that converts the first light into second light that belongs to a second wavelength band different from the first wavelength band, and an optical element that transmits the second light emitted from the wavelength converter. An air layer is provided between the wavelength converter and the optical element. A length of the air layer along the direction of the optical axis of the optical element is greater than or equal to 0.3 μm but smaller than or equal to 9.0 μm. The optical element has a coefficient of linear expansion smaller than or equal to 65×10−7/° C. at temperatures ranging from 100° C. to 200° C., and a thermal conductivity greater than or equal to 1.0 W/m·K.