Fluorescence Reader Substrate Surface Relief and Wetting Layer

The patent introduces an optically wetting layer as an intermediary substance between the substrate and the surrounding medium. This layer has refractive index properties that prevent total internal reflection at the substrate surface, allowing trapped fluorescent light to escape. The wetting layer acts as a mediator that changes the optical conditions at the interface without requiring complex structural modifications to the substrate itself.

The patent changes the optical parameters at the substrate surface by applying an optically wetting layer with specific refractive index characteristics. This parameter change modifies the critical angle for total internal reflection, enabling light that would otherwise be trapped to escape from the substrate. The solution involves changing the physical-chemical properties (refractive index) rather than the geometric structure.

The patent employs asymmetric surface relief structures on the substrate that are designed to match the asymmetric emission pattern of fluorescent molecules. These structures create preferred light extraction pathways that align with the maximum emission angle, thereby improving detection efficiency. The asymmetric geometry is specifically tailored to the physics of fluorescence emission rather than being a symmetric simplification.

The patent addresses the angular mismatch problem by introducing surface relief structures that operate in the spatial dimension. These structures create three-dimensional optical pathways that guide light extraction at optimal angles, effectively adding a dimensional solution to an angular alignment problem. The relief structures modify the light propagation in the vertical dimension to achieve optimal horizontal emission angles.