Light Extraction Apparatus with Sparse Fluorescent Coating

The invention divides the traditional thick fluorescent layer into multiple thin layers separated by light-reflecting structures. Specifically, it uses a multi-layered configuration where fluorescent layers are interspersed with light-reflecting layers, creating a segmented structure that increases the effective absorption path for UV light while maintaining visibility for emitted light. This segmentation allows the system to achieve high UV absorption without sacrificing visible light penetration, as each thin fluorescent layer can be optimally illuminated by reflected UV energy from subsequent layers.

The invention introduces a vertical dimension to light interaction by implementing alternating fluorescent and light-reflecting layers. Instead of simply increasing the thickness of a single fluorescent layer (one-dimensional approach), the patent creates a multi-dimensional structure where UV light can be reflected back and forth between layers, increasing the effective interaction path length without proportionally increasing the physical thickness of fluorescent material. This dimensional approach allows simultaneous optimization of both UV absorption and visible light transmission.

The invention implements preliminary action by placing light-reflecting layers between and behind the fluorescent layers. These reflective structures are positioned in advance to intercept UV light that passes through the first fluorescent layer and reflect it back, ensuring that the UV energy is utilized by subsequent fluorescent layers. This preliminary positioning of reflective elements guarantees that UV energy is not wasted, allowing thin fluorescent layers to achieve adequate UV absorption through multiple reflection cycles.

The patent ensures continuity of useful action by creating a system where UV light continuously interacts with fluorescent layers through multiple reflections. The light-reflecting layers maintain continuous UV energy delivery to the fluorescent materials, ensuring that even thin fluorescent layers receive sufficient UV exposure to emit visible light effectively. This continuous interaction pattern maintains high absorption efficiency without requiring thick fluorescent layers that would block visible light.

The invention segments the thick fluorescent layer into multiple thin alternating layers with light-reflecting interspersed layers. This segmentation allows UV energy to be absorbed progressively across multiple interfaces rather than requiring a single thick layer. Each thin fluorescent layer absorbs UV energy efficiently, and the reflective layers ensure that unabsorbed UV energy is redirected to subsequent layers, maintaining high overall absorption efficiency while keeping each fluorescent layer thin enough to allow visible light transmission.

The light-reflecting layers serve as intermediaries between the UV light source and the fluorescent layers, and between the fluorescent layers and the external environment. These intermediary reflective layers redirect UV energy to ensure complete absorption by the fluorescent materials, while simultaneously allowing the visible light emitted by the fluorescent layers to pass through to the observer. This intermediary structure decouples the absorption function from the transmission function, resolving the contradiction between energy efficiency and brightness.