Developing polymeric antireflective coatings

摘要

As polymers become more widely used in optics antireflective coatings need to be designed specifically to suit these new components. Modifications are being made to the current high temperature coating process to allow for inorganic metaloxides to be applied to polymer optics. This is not however the only hurdle that needs to be overcome to produce asatisfactory antireflective coating on polymers. Inorganic metal oxides and polymer components have a significantdifference in thermal expansion meaning that defects such as delamination and cracking can occur. These defectssignificantly shorten the lifetime of the optical component. A new antireflective coating has been developed that has a similar thermal expansion coefficient to that of the polymersubstrate, meaning that defects caused by thermal stress do not occur. These are polymeric coating with a refractiveindex of 1.31 and 1.34, lower than that of magnesium fluoride (MgF_2) at 1.38. These coatings have antireflectiveproperties superior to those of current commercially available single layer inorganic antireflective coatings. Polymer antireflective coatings cannot be applied by vacuum deposition. Dip coating was evaluated as a method for filmapplication. Dip coating allows control of the film thickness through varying the properties of the coating solution. It alsoallows for uniform films that can be inspected visually for variances.