How are surgical lasers different from the lasers that they use on Star Trek?
Lasers, as you probably know, produce intense radiation using a specific quantum mechanical mechanism (“Light Amplification by Stimulated Emission of Radiation” — LASER). Whether the laser is used for surgery or not, the mechanism is the same. Larger lasers can produce more energy. (Actually, I’m not sure the Star Trek characters are using “lasers” at all — I thought they called them “phasers”, in which case I haven’t the slightest idea was 24th(?) century technology they’re using!
