Which test is used to determine AR coating scratch resistance?

• A. Bayer
• B. Mohs
• C. Brinell
• D. Vickers

Answer: (A)

Evaluating AR coating scratch resistance hinges on simulating real wear on the thin film and seeing how well the coating holds up. The Bayer test is a procedure specifically developed for this purpose on anti-reflective coatings. It uses a standardized abrasion method with a controlled abrasive element and load over a set distance, then checks whether scratches appear and how severe they are. This targeted approach matches the behavior of thin optical coatings on lenses, providing a meaningful rating of how durable the AR layer will be in everyday use. In contrast, Mohs scratch testing measures how a material can scratch or be scratched relative to minerals—it's not calibrated for thin films. Brinell and Vickers are indentation hardness tests for bulk materials and can damage the substrate when applied to delicate coatings, making them less appropriate for assessing AR coating durability.