The growth of the radiation field in the laser resonator cavity. As the light wave bounces back and forth between the cavity mirrors, it is amp stimulated emission on each pass through the active medium.
Amplitude
The maximum value of the electromagnetic wave, measured from the mean to the extreme; put simply, the height of the wave.
Angle of Incidence
Angstrom
A unit of measurement for a wavelength of light (written Å), equal to one ten billionth of a meter (10-10 meter). (Used occasionally.)