Polymeric ophthalmic lenses (plastic) have become increasingly popular recently due to their excellent optical properties, impact resistance, lightweight, etc. These plastic materials, however, tend to be relatively soft and scratch more easily than glass. Hence hard coatings are applied to impart increased scratch resistance.
To assess the effectiveness of a coating's resistance to scratch, there are a number of instruments. Similarly, there are many instruments available to assess the resistance to penetration for coatings.
Unfortunately, all these methods are destructive in nature and make scratches or dents on the surface. There is high-end lab-scale equipment like Nano Indentors for this purpose but these are very expensive.
We need a cost-effective method (equipment) that could measure the scratch resistance in a non-destructive way with accuracy and repeatability. The equipment needed should be portable, inexpensive, and simple to install and operate in a retail environment.