Would water from a running fire hydrant dry rot or ruin your tires on your car?
I use Martin Yale Rubber Roller Cleaner and Rejuvenator Spray from my local office supply. Not sure if Staples, Office Depot, Office Max or other stores like that will have it. Google around and good luck!
For the MgF2 to be non-reflective, destructive interference between the reflected ray off the the surface of the MgF2-air interface and the ray reflected off the MgF2-glass surface must be 1/4 of a wavelength. The index of refraction of the glass is not involved so the answer for both parts A) B is the same So t 1/4λ2 (where λ2 is the wavelength in the MgF2 which n2*λ. λ is the wavelength in air) So t min (n2*λ)/4
