Stable, absorption free optical coatings of higher quality
Optical coating deposition on plastic substrates is widely used in many industrial sectors; for instance in the area of optical coatings for ophthalmic plastic lenses. The key objective in the treatment of plastic substrates is to develop highly durable and stable coatings at a reduced cost. The PACECO project focused on improving a patented reactive low voltage ion plating technology for optical thin film deposition. In particular, the technology doesn't require any substrate heating and offers a very short deposition time, while it significantly reduces energy consumption. In comparison to solvent-employing techniques, the new deposition process is also more environmentally friendly. Although the initial technology was capable of producing very stable, dense and durable optical coatings, it also led to undesirable residual optical absorption. In order to avoid thermal post-treatment, researchers from the Romana Film Sottili Srl introduced a second plasma in the process of producing absorption-free, high quality optical coatings. More specifically, a system generating radio frequency (RF) or direct current (DC) pulsed plasma surrounds the substrates and induces ion bombardment of the growing optical film. As a result the reactivity of the deposition process is improved and the residual optical absorption is reduced to one tenth of the original value. Furthermore, internal stress applied on the deposited film is minimised. In comparison to solvent-employing techniques, the new optical coating deposition process is significantly more environmentally friendly. The new technique introduced doesn't require any substrate heating and offers a very short deposition time, while it significantly reduces energy consumption.
