REPAIR & TROUBLESHOOTING - USAF Removing Optical Coatings

Final technical report from the Air Force Weapons Laboratory (AFWL) detailing chemical methods for removing thin-film optical coatings from precision substrates. This repair and troubleshooting guide presents a practical alternative to traditional mechanical polishing for reclaiming valuable optical components. The core advantage of the chemical approach is its selectivity: individual coating layers within a multi-layer design can be stripped away while preserving underlying substrates and layers intact—a capability that mechanical polishing cannot match. The manual covers removal of metallic and dielectric coatings including gold, silver, chromium, thorium, fluoride, and zinc selenide applied to molybdenum, titanium, zirconium-molybdenum alloys, germanium, and silicon substrates. Technical sections detail chemical corrosion properties, appropriate reagents, and optimal process conditions for achieving efficient removal while minimizing substrate degradation and reducing toxic byproduct generation. The document establishes baseline data for commonly deployed infrared optical coatings and outlines a research roadmap for extending the methods to additional coating types and substrates across the near-infrared, visible, and ultraviolet spectral ranges.