Q switching

Q-switching, sometimes known as giant pulse formation or Q-spoiling, is a technique by which a laser can be made to produce a pulsed output beam. The technique allows the production of light pulses with extremely high (gigawatt) peak power, much higher than would be produced by the same laser if it were operating in a continuous wave (constant output) mode. Compared to modelocking, another technique for pulse generation with lasers, Q-switching leads to much lower pulse repetition rates, much higher pulse energies, and much longer pulse durations. The two techniques are sometimes applied together.

Applications

Q-switched lasers are also used to remove spots and tattoos on body and face. They are used to shatter tattoo pigment into particles that are cleared by the body's lymphatic system. Full removal can take between six and twenty treatments depending on the amount and color of ink, spaced at least a month apart, using different wavelengths for different colored inks.