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Optical Engineering

Application of plasma polymerization on ophthalmic lenses: equipment and processes
Author(s): Christian Wohlrab; Markus Hofer
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Paper Abstract

The use of plastic as a substrate material for optical lenses has been increasing in importance due to its smaller density, simpler machining, and lower price. However, scratches present a major problem wherever the lens surface is exposed to the environment. Various processes have thus been developed to protect the surfaces with hard coatings. The most common technique is dipping, but spinning and spraying are other methods to apply lacquer. Common to all these techniques are the required posttreatments such as drying and heat or UV curing. Safety considerations, as well as the long processing time and the handling required between the different steps, have led to the development of new technologies. Plasma polymerization, a technology relying on plasma-enhanced chemical vapor deposition, is used to deposit dense organic layers with reproducible, well-defined surface properties. In contrast to dip coating, plasma polymerization coats even strongly curved structures with good uniformity. This is important for bifocal or trifocal lenses, which have sharp edges on the surface. Due to the wide range of refraction indexes (about n = 1.5 to 1.8) available by using different monomers, even the latest high-index materials can be coated without disturbing interference fringes. After a survey of plasma polymerization basics, some aspects of industrial equipment and processes for ophthalmic applications are presented. An outlook into the future of plasma polymerization for optical applications concludes the paper.

Paper Details

Date Published: 1 September 1995
PDF: 7 pages
Opt. Eng. 34(9) doi: 10.1117/12.205677
Published in: Optical Engineering Volume 34, Issue 9
Show Author Affiliations
Christian Wohlrab, Balzers Ltd. (Liechtenstein)
Markus Hofer, Balzers AG (Liechtenstein)

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