Optical Disc Bi-Layer Absorber for Stray Light Reduction

The patent transitions from flat two-dimensional surfaces to three-dimensional micro-lens arrays. Each micro-lens element creates multiple internal reflections and refractions, effectively increasing the light interaction path length and absorbing area without significantly increasing the overall device footprint. The micro-lens structure transforms the absorption mechanism from surface-level to volumetric, solving the contradiction between small absorbing area and structural simplicity.

The patent employs composite structures combining micro-lens arrays with specific refractive index materials. The micro-lens elements are made from materials with optimized optical properties that enhance light trapping and absorption. This composite approach allows the system to achieve large effective absorbing area through the micro-structured surface while maintaining relatively simple macro-scale construction.

The patent divides the absorption surface into multiple discrete micro-lens elements arranged in arrays. Each micro-lens acts as an independent light-trapping unit, and the segmented structure can be manufactured using standard micro-fabrication techniques. This segmentation allows the complex optical function to be achieved through repetition of simple, manufacturable units, balancing absorption effectiveness with manufacturing ease.

The patent optimizes specific parameters of the micro-lens structure including radius of curvature, depth, spacing, and refractive index to maximize stray light absorption. By carefully controlling these geometric and material parameters during manufacturing, the system achieves high absorption effectiveness while maintaining compatibility with existing fabrication processes. The parameter optimization transforms the manufacturing challenge into a controlled process with defined specifications.