Refractive index database

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Optical constants of Ir (Iridium)
Schmitt et al. 2022: n,k 0.200–20.0 µm; MS deposition

Wavelength: µm

Complex refractive index (n+ik)[ i ]

n   k   LogX   LogY   eV

Derived optical constants

Conditions & Spec sheet

n_is_absolute: true
wavelength_is_vacuum: true
film_thickness: 78e-9
substrate: Si
deposition_method: MS


Iridium coating deposited by magnetron sputtering (MS).


P. Schmitt, N. Felde, T. Doehring, M. Stollenwerk, I. Uschmann, K. Hanemann, M. Siegler, G. Klemm, N. Gratzke, A. Tuennermann, S. Schwinde, S. Schroeder, A. Szeghalmi. Optical, structural, and functional properties of highly reflective and stable iridium mirror coatings for infrared applications, Opt. Mater. Express 12, 545-559 (2022) (See supplementary materials. High-resolution data kindly provided by Paul Schmitt.)


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Iridium, Ir

Iridium (Ir) is a dense, lustrous, and corrosion-resistant transition metal. It is one of the rarest elements in the Earth's crust and has a high melting point, making it ideal for high-temperature applications. Although not transparent, its optical properties are relevant in thin film coatings. Thin layers of iridium can be used as a coating material for mirrors in certain specialized optical systems, including X-ray telescopes. Moreover, the metal is often used in combination with other materials to form highly stable, temperature-resistant, and chemically inert optical surfaces. Its high cost often restricts its usage to specialized applications where other materials would fail. Given its excellent resistance to chemical corrosion, iridium is also used in electrodes for the chlor-alkali process and in certain types of spark plugs.

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