What should signage indicate in the fiberscope room signage

No free access. Fiberscope is the use of glass or acrylic resin by the high transmittance of very fine fibers into a light-guided beam, used to diagnose bronchial diseases of an instrument, belonging to the high-precision medical equipment, the equipment room in order to protect the safety of the equipment, do not allow unrelated people, etc. to enter, and its signage should indicate that it is prohibited to enter at will.