Full Width at Half Maximum

Known by its common abbreviation, “FWHM“, this refers to the mathematical function defined as the difference between the two extreme values of an independent variable at which the dependent variable is equal to half of its maximum value. In other words, it is the width of a spectrum curve measured between those points on the y-axis that are half the maximum amplitude. Full Width at Half Maximum is a common form of measurement for pulse waveforms, and the spectral width of sources used for optical communications. FWHM is also used in signal processing to define bandwidth as the “width of frequency range where less than half the signal’s power is attenuated.”