WATT A unit of power (equivalent to one Joule per second) used to express laser
WATT/cm(2) A unit of irradiance used in measuring the amount of power per area
of absorbing surface, or per area of CW laser beam.
WAVE An sinusoidal undulation or vibration; a form of movement by which all
radiant electromagnetic energy travels.
WAVELENGTH The length of the light wave, usually measured from crest to crest,
which determines its color. Common units of measurement are the micrometer (micron),
the nanometer, and (earlier) the Angstrom unit.
WINDOW A piece of glass with plane parallel sides which admits light into or
through an optical system and excludes dirt and moisture.