To ensure Class 4 and Class 3B laser beams do not escape from laser laboratory or medical facilities, including hospital theatres, certified laser blocking material should be installed. Ordinary curtains are rarely capable of stopping a laser beam and specially designed certified laser blocking material must be used (certified to IEC/EN 60825-4).
Also, production facilities using Class 1 lasers, which are Class 4 under service conditions, may require ceiling-mounted curtains to allow other work to continue safely in the same room during service…
‘Archaic rules’ torn up to green light new nuclear
They are hedging their bets like any sensible business, but around 90% of the power that Google etc buy is renewable and every week or so they...