Fungus: how to prevent growth and remove it from optical instruments

摘要

In hot and humid climates it is common for fungus to grow on the surfaces of optical components. Airborne fungal spores settle on optical surfaces and develop into organisms that digest organic material, such as oils from fingerprints or lens coatings, producing hydrofluoric acid as a waste product. This acid in turn destroys any lens coatings and permanently etches the glass.In its initial stages, fungus, as pictured in Figure 1, may not be perceivable by the clinician. However, over time the fungus will cover the lens surface in a web-like manner, initially causing a very slight loss of image brightness, followed by decreased contrast due to light reflecting off the fungus. In its final stages, the fungus etches the outer coatings of the lens and image sharpness deteriorates.