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Broadband and Crack-Free Antireflection Coatings by Self-Assembled Moth Eye Patterns

pubblicazioni - Articolo

Broadband and Crack-Free Antireflection Coatings by Self-Assembled Moth Eye Patterns

Sono state studiate strutture antiriflesso (AR) a banda larga e quasi-omnidirezionali. La trasmissione su vetro viene migliorata del 2% su una singola superficie. Il coating lavora per un ampio campo di angoli di incidenza tra 0° e 50° e per lunghezze d’onda che vanno da visibile al vicino infrarosso.

We report broadband and quasi-omnidirectional antireflective (AR) structures inspired to the nipple arrays of moth eyes. These nanocoatings, based on thin elastomeric films, are prepared by simple self-assembly processing of a co-polymer specifically designed to this purpose, and PDMS replica molding. Typically, their surface is covered by a compact distribution of hemispherical nanodomes of about 250 nm in diameter and about 100 nm in height.

When these novel nanostructures are applied on a single glass surface, a maximum of 2% transmission enhancement (equivalent to a 50% reduction of the reflected component) towards wavelengths ranging from visible to near IR region is obtained. A considerable AR power is observed also at a wide range of incident angles ranging from normal to 50°.

These properties could be attributed to an optimized graded refractive index profile resulting from the randomly distributed and close-packed nanodomes. Moreover, thanks to their elastomeric nature, these crack-free films can be easily applied on glass, as stickers, and periodically replaced, thus offering the possibility of easy dirt removal from an optical device.

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