This is a classic article from Â鶹´«Ã½’s archive, republished as part of our 50th anniversary celebrations
AN ORDINARY light source emits energy as short wave trains containing many frequencies. The waves are not a continuous stream of ripples, as is the case with transmitted radio waves; but if physicists could produce monochromatic light which was coherent like radio waves, it would have similar applications. A beam of such light would have very low dispersion and might be used for communications.
The Bell Telephone Laboratories at Murray Hill, New Jersey, have made an optical maser which goes some way towards…
