Metallic Coatings

Metals are the most common materials for mirror fabrication. Polished metals, especially gold, copper and bronze, were used as mirrors in the ancient world. In the middle-ages, mirrors with relatively constant reflectance in the visible spectral range were fabricated using tin foils and mercury which were put on glass. The era of thin film metal coatings on glass began in the 19^th century when Justus von Liebig discovered that thin films of silver can be manufactured using silver nitrate and aldehyde. For applications in precision optics and laser physics, mirrors are produced by using the evaporation or the sputtering technique.

LAYERTEC uses magnetron sputtering for manufacturing metallic coatings with extremely low scattering losses. Transparent, i.e. very thin, metal coatings can be produced with high accuracy. For detailed information about metallic mirrors and neutral density filters please see page Silver Mirrors for Ultrafast Lasers (550 – 1100 nm) and Front Surface Silver Mirrors (400 – 4000 nm). Fig. 1 gives an overview about the reflectance of the most common metals. In the following, we give some advice about the use of these metals and the role of protective coatings.