Dress code for the clean tent
I was not aware of it, but apparently we humans are like snakes: every month, we change our complete skin, so no wonder that we are constantly shedding skin particles, hairs and water drops or worse. But if you work with optical elements, cleanliness has to become an obsession. Dust on your samples could scatter light in unwanted directions or even scratch their perfect surfaces.
The Metrology Light Source of the PTB offers a possibility to measure sensitive samples like the long EMIL-Mirror under very clean conditions in a reflectometer. The huge cylindric instrument is surrounded by flexible walls of plexiglass, forming a “clean tent”, which provides all the advantages of a clean room: Before entering through an airlock, everybody has to dress up in a white, closed coverall, cover the shoes in plastic, put on a cap, a face mask and of course, long gloves. The air is filtered, dry and cold, a constant airflow carries remaining dust particles outside.
Working here needs steady hands and full concentration, of course without the help of chocolate cookies!
More about clean rooms in general is here.