A device that has the effect of a shutter moving rapidly in and out of the beam to spoil the resonator’s normal Q, keeping it low to prevent lasing action until a high level of energy is stored. Result: a giant pulse of power when normal Q is restored.

A unit of angular measurement equal to the angle subtended at the center of a circle by an arc whose length is equal to the radius of the circle.
Example: 1 radian = ~ 57.3 degrees; 2π radians = 360 degrees

Brightness; the radiant energy per unit solid angle and per unit projected area of a radiating surface.

Energy traveling as wave motion; specifically, the energy of electromagnetic waves (light, X-rays, radio, gamma rays).

The rate of emission or transmission of radiant energy.