In the technique of Q-switching, energy is stored in the amplifying medium by optical pumping while the cavity Q is lowered to prevent the onset of laser emission. The higher the quality factor, the lower the losses. Quality factor (Q factor) is defined as the ratio of the energy stored in the optical resonant cavity to the energy loss per cycle.

Q-switching is a means of creating very short pulses (5-100 ns) with extremely high peak powers. Q-Switch: An optical device (Pockels cell) that controls the storage or release of laser energy from a laser optical cavity. Pulse: The brief span of time for which, the focused and scanned laser beam interacts with a given point on the skin (usually in milliseconds, nanoseconds) The energy fluence determines the amount of laser energy delivered in a single pulse and is expressed in joules/cm 2

Power density (irradiance): The quotient of incident laser power on a unit surface area, expressed as watts/cm 2Įnergy fluence: The energy contained within light is expressed in joules (J). Power: The rate at which energy is emitted from a laser Population inversion: The state present within the laser optical cavity (resonator) where more atoms exist in unstable high-energy levels than their normal resting energy levels Monochromatic: Light energy emitted from a laser optical cavity of only a single wavelengthĬoherence: All waves are in phase with one another in both time and spaceĬollimation: All waves are parallel to one another with little divergence or convergence Photon: A quantum of electromagnetic radiation or light Optically pumped laser: A laser where electrons are excited by the absorption of light energy from an external sourceĮlectromagnetic radiation: A complex system of radiant energy composed of waves and energy bundles that is organized according to the length of the propagating wave

Pump: The electrical, optical, radiofrequency or chemical excitation that provides energy to the laser medium Laser medium: A material or substance of solid, liquid, or gaseous nature that is capable of producing laser light due to stimulated electron transition from an unstable high-energy orbit to a lower one with release of collimated, coherent, monochromatic light Laser: An instrument that generates a beam of light of a single wavelength or color that is both highly collimated and coherent an acronym that stands for light amplification by the stimulated emission of radiation

Radiant energy definition