engleski

A comparative study of the stability of hard coatings produced with and without ion assistance

A primary requirement of a precision optical coating is long-term and short-term stability. The spectral features of conventionally deposited (e-beam gun generated vapor cloud depositing onto heated substrates) hard oxide coatings are sensitive to temperature and humidity changes due to the relatively high degree of columnar structure and the concominant low packing density that results from conventional hard oxide deposition. Coatings deposited using ion assisted deposition (IAD) exhibit significantly higher packing densities and, therefore, are less sensitive to environmental changes. A small environmental chamber designed to mount in spectrophotometer has been constructed to study the influence of temperature and humidity changes on the spectral performance of coatings. We will reposrt on the results of studies of thermally induced changes in the spectral performance of optical multilayers produced both conventionally and with IAD. The chamber enables us to study these systems at temperatures ranging from -15 deg C to +200 deg C in air and vacuum. reversible and irreversible phenomena such as water sorption and desorption will be discussed.

thin films; multilayers; ion assisted deposition

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