Coating on Plastic
Quartz (sodium dioxide, n = 1.48) is used because plastic cannot be heated enough for magnesium fluoride to adhere to it.
- Lens is cleaned and baked to remove water vapor.
- Lens is heated to 100o C.
- Thin film of high index material is deposited to increase the index of the ‘lens surface’.
- After coating lens with quartz layers, a hydrophobic layer is deposited to aid in cleaning and hardness.