Antirreflejos

Antirreflejos, or anti-reflective coatings, are thin-film coatings applied to optical surfaces to reduce reflections and increase light transmission and contrast. They are widely used on eyeglasses, camera and smartphone lenses, display panels, microscopes, telescopes, and solar panels, as well as on architectural glass and insect screens.

They work primarily through thin-film interference. A single-layer coating places a material with a suitable refractive index on the surface and uses a thickness close to one-quarter of the target wavelength to cancel reflections by destructive interference. Multi-layer stacks alternate materials with different refractive indices to extend low reflectance over a broader spectral range and various viewing angles. In addition to interference-based designs, some coatings rely on subwavelength nanostructures (moth-eye textures) that gradually match refractive indices to suppress reflections across wide bands.

Materials and architectures commonly used include magnesium fluoride (MgF2), silicon dioxide (SiO2), titanium dioxide (TiO2), tantala (Ta2O5), and aluminum oxide (Al2O3). Coating thicknesses are typically on the order of a quarter of the target wavelength, with multi-layer stacks ranging from two to several dozen layers to tailor spectral performance. Gradient or broadband designs aim for higher transmittance from the visible into near-infrared.

Manufacture involves vacuum deposition methods such as physical vapor deposition (PVD), sputtering, chemical vapor deposition (CVD), or atomic layer deposition (ALD), sometimes with post-deposition curing and protective overcoats. Durability depends on adhesion, environmental exposure, and the substrate; coatings may be abrasion- or chemical-resistant to varying degrees and can require careful cleaning to preserve performance.

Applications include improving visibility and contrast in eyewear and cameras, increasing display readability, and boosting the efficiency of solar modules and optical instruments. Standards exist to assess reflectance, transmittance, and durability of optical coatings.