Optical, structural, and functional properties of highly reflective and stable iridium mirror coatings for infrared applications

Metallic coatings are essential for numerous optical systems due to their high and broadband reflectivity in the infrared spectral range. In contrast to well-established (protected) silver and gold mirror coatings, iridium is environmentally durable, referring to ISO 9211-3 and thermally stable up to 600 °C even without protective layers, as demonstrated. Additionally, the optical and related structural properties of atomic layer deposited (ALD) and magnetron sputtered (MS) Ir coatings were investigated using spectrophotometry, FTIR, ellipsometry, WLI, AFM, XRR, XRD, SEM, and electrical resistivity measurements. The properties of Ir ALD and Ir MS coatings differ due to their topography and microstructure.