Antireflect

Antireflect (commonly used as antireflective) describes materials and surface treatments designed to reduce unwanted reflection of light. The goal is to increase transmission into or out of an optical element by minimizing the fraction of incident light that is reflected. Antireflective treatments are important in optics, imaging, photonics, displays, and energy applications.

Principles used to achieve antireflection include thin-film interference, graded refractive-index layers, and subwavelength surface texturing. Single-layer coatings use destructive interference at a design wavelength, while multilayer stacks broaden the low-reflectance band. Nanostructured "moth-eye" surfaces create a gradual refractive-index transition and offer broadband, angle-tolerant performance.

Common fabrication methods include physical vapor deposition, sputtering, chemical vapor deposition, sol-gel processes, and lithographic or etching techniques for nanostructures. Coating materials are chosen for refractive index, durability, and environmental stability; additional hard or hydrophobic overcoats are often applied to improve scratch resistance and repel contaminants.

Performance is characterized by reflectance, bandwidth, polarization and angle dependence, and environmental durability. Well-designed antireflective coatings can reduce surface reflectance from several percent to fractions of a percent at target wavelengths. Trade-offs include increased complexity and cost, spectral and angular limits of effectiveness, and potential sensitivity to surface damage.

Applications span eyeglasses and camera lenses, solar panels, displays and windows, scientific instruments, and laser systems. Continued development focuses on broader bandwidths, durability, simpler fabrication, and biomimetic nanostructures for improved omnidirectional performance.