Use of Nomarski phase interference contrast microscopy to indicate areas of damage and subsequent chemical attack or contamination in anti-reflective coatings on optical elements or delamination failures. Here are four examples:
Example 1: Humidity acting upon an underlayer film in a multi-layer optical coating through a surface pinhole in the outer protective layer caused the damage above and the surface debris due to corrosive chemical reaction.
Example 2: An unusual form of underlayer moisture attack in a multi-layer anti-reflective coating in which the attack followed a rather random appearing path. In this case, diffusion rates are greatly aided by defects, so the path is likely one of maximal lattice defects such as might be found in a highly oxygen-deficient oxide.
Example 3: Damage caused to an anti-reflective coating upon attempted cleaning of high-value optical elements due to chemical attack through defects by the cleaning chemical. The Nomarski method greatly enhances the visibility of the extensive underlayer damage.
Example 4: Delamination of an optical coating occurred when it was subjected to a low-adhesion tape pull test. The optical coating could not be seen on the tape by the naked eye, but with the use of the Nomarski phase interference contrast microscopy, it was easily visible, as were the size, elongation, and completeness of the film failure.
Reach out today to explore your optical coating concerns. We’re eager to collaborate with you in devising a customized plan that not only addresses but also resolves your specific issues effectively.
