In optics, a Gaussian beam is an idealized beam of electromagnetic radiation whose amplitude envelope in the transverse plane is given by a Gaussian function; this also implies a Gaussian intensity (irradiance) profile. This fundamental (or TEM00) transverse Gaussian mode describes the intended output of many lasers, as such a beam diverges less and can be focused better than any other. When a Gaussian beam is refocused by an ideal lens, a new Gaussian beam is produced. The electric and magnetic field amplitude profiles along a circular Gaussian beam of a given wavelength and polarization are determined by two parameters: the waist w0, which is a measure of the width of the beam at its narrowest point, and the position z relative to the waist.
A 5 mW green laser pointer beam, showing the TEM00 profile
Transverse amplitude profile of the lowest order even Ince-Gaussian modes.
Intensity profiles of the first 12 Laguerre-Gaussian modes.
Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultraviolet, and infrared light. Light is a type of electromagnetic radiation, and other forms of electromagnetic radiation such as X-rays, microwaves, and radio waves exhibit similar properties.
A researcher working on an optical system
The Nimrud lens
Reproduction of a page of Ibn Sahl's manuscript showing his knowledge of the law of refraction
The first treatise about optics by Johannes Kepler, Ad Vitellionem paralipomena quibus astronomiae pars optica traditur (1604), generally recognized as the foundation of modern optics.