W

Watt

A unit of power (equivalent to one Joule per second) used to express laser power.

Watt per cm²

A unit of irradiance used in measuring the amount of power per area of absorbing surface or per area of CW laser beam.

Wave

A sinusoidal undulation or vibration. A form of movement by which all radiant electromagnetic energy travels.

Wavefront

A surface connecting all field points of electromagnetic energy that are equidistant from the source.

Waveguide

A device (e.g., optical fiber) that confines or guides electromagnetic waves along a path defined by the construction of the guide.

Wavelength

The distance between successive peaks, troughs, or identical parts of a wave, measured in nanometers or microns. Equal to the speed of the wave divided by its frequency.

Wave number

The number of complete wave cycles of an electromagnetic field that exist in a given distance of linear space, expressed in reciprocal centimeters (cm-1).

Window

A piece of glass with plane parallel sides that admits light into or through an optical system and excludes dirt and moisture.