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 metal
oxides to be applied to polymer optics. This is not however the only hurdle that needs to be overcome to produce a
satisfactory antireflective coating on polymers. Inorganic metal oxides and polymer components have a significant
difference in thermal expansion meaning that defects such as delamination and cracking can occur. These defects
significantly 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 polymer
substrate, meaning that defects caused by thermal stress do not occur. These are polymeric coating with a refractive
index of 1.31 and 1.34, lower than that of magnesium fluoride (MgF<sub>2</sub>) at 1.38. These coatings have antireflective
properties 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 film
application. Dip coating allows control of the film thickness through varying the properties of the coating solution. It also
allows for uniform films that can be inspected visually for variances.
Although metal halide anti-reflective (AR) coatings are widely used by manufacturers of electronics equipment, high
application temperatures mean that they can only easily be applied to glass substrates. Screens made from plastics
materials can be coated but the process requires additional steps to prevent damaging the substrate.
A new, easily applied anti-reflective coating has been designed which can be applied to both plastic and glass substrates.
The single layer coating applied to an acrylic substrate has proven to be better performing than current commercial single
layer anti-reflective coatings. This performance has been achieved from an amorphous fluoropolymer solution which is
dip coated onto the substrate.