| greatest distance between two points on a specified axis perpendicular to the beam axis, where the pulse-pressure-squared integral falls below its maximum on the specified axis by a specified amount
Note 1 to entry: Commonly used beamwidths are specified at −6 dB (w6), −10 dB (w10) and −20 dB (w20) levels below the maximum. The decibel calculation implies taking 10 times the logarithm (to the base 10) of the ratios of the integrals.
Note 2 to entry: The term "beamwidth" has different meanings in optical fibre communication (see IEV 731-01-35) and in relation to antennae (see IEV 712-02-33).
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