Iridescence from Total Internal Reflection at 3D Microscale Interfaces: Mechanistic Insights and Spectral Analysis

Area of Science:

• Optics
• Materials Science
• Nanotechnology

Background:

• Structural coloration arises from light interacting with micro- or nanostructures.
• Total internal reflection (TIR) interference is a mechanism producing vivid, angle-dependent colors.
• Understanding TIR interference in 3D microstructures is key for advanced optical materials.

Purpose of the Study:

• To experimentally investigate and optically model structural coloration from TIR interference in 3D microstructures.
• To develop a framework for deconstructing complex iridescence into fundamental optical components.
• To demonstrate methods for tailoring iridescent properties of microstructured surfaces.

Main Methods:

• Ray-tracing simulations combined with spectral analysis and color visualization.
• Fabrication of 3D microstructures using chemical etching, multiphoton lithography, and grayscale lithography.
• Experimental comparison of simulated and fabricated microstructures under various illumination conditions.

Main Results:

• Accurate modeling of iridescence generated by hemicylinders and truncated hemispheres.
• Deconstruction of spectral features linked to specific ray trajectories within microstructures.
• Demonstration of tunable color-traveling effects using patterned microstructure arrays.

Conclusions:

• A robust conceptual framework for understanding multibounce TIR interference in 3D microstructures is established.
• Experimental validation confirms the predictive power of the optical modeling approach.
• This work provides pathways for designing and customizing reflective iridescence in microstructured surfaces.