The surface of the infrared thermal imaging lens is attached with a fine anti-reflective coating. Do not use too much force to damage the anti-reflective coating. If professional cleaning equipment is available, you can clean the lens surface particles via compressed air tank or dry nitrogen ion gun. Otherwise, soak the flannelette in lens cleaner containing alcohol, ethanol or vinyl. Before cleaning, remove the excess liquid from the cloth and gently wipe the lens surface in a circular motion.
How to clean lens?