Patent ID: 8512322

Claim:
A dermatological device for treating skin comprising: a light source configured to emit light at a wavelength λ; a sapphire substrate; and an antimicrobial layer disposed directly on a surface of the substrate, the antimicrobial layer positioned between the substrate and the skin during treatment, the antimicrobial layer having a refractive index n substantially different than a refractive index of skin, thus providing a refractive index mismatch between the antimicrobial layer and the skin; wherein the antimicrobial layer has a thickness selected based on an integer multiple of a half-wave layer thickness defined by the equation: half-wave layer thickness=½[λ/ n], such that the selected thickness of the antimicrobial layer substantially minimizes refractive losses associated with the refractive index mismatch between the antimicrobial layer and the skin.