The rate of energy delivery. Power (or more correctly, radiant flux) is used to express the output of continuous (CW) lasers and is measured in Watts (W). One Watt is a Joule per second. The average power from a pulsed laser is the product of energy per pulse (in Joules) and pulse repetition frequency (in Hertz). For example, if a giant pulsed laser produces 10 pulses per second (i.e. 10Hz) and the energy of each pulse is 100mJ (1 x 10-1 J), the average power is 10 * 1 x 10-1 equals 1 Watt.