Continuous Wave Laser power is fixed or variable, but not delivered in a discrete pulse envelope. Pulsed Laser energy is delivered in a single discrete pulse at a specified repetition rate. Power The average power of a continuous wave (cw) laser beam expressed in watts (W). Energy per Pulse The energy of an individual pulse expressed in joules (J). Pulse Repetition Rate The rate at which pulses are repeated in a uniformly pulsed train of pulses expressed at the frequency of repetition of the pulses in the unit of hertz (pulses per second, Hz). Gaussian Criteria The definition as used in the ANSI Z136.1 Standard for both beam diameter and beam divergence, require that these quantities be measured at the 1/e power point (63.2%) on the ideal Gaussian beam intensity profile. Note that most laser equipment manufacturers specify these beam properties at the 1/e2 power point (86.5%), which is a factor of 1.414 larger than the 1/e power point. Beam Dimension Beam size (typically diameter) in millimeters, measured on the longest dimension. Beam Divergence Change in beam size with respect to distance measured in milliradians. |