A 2-by-2 matrix describing the effect of an optical element on a laser beam
|absorption coefficient factor|
Describes light`s ability to be absorbed per unit of path length.
|absorption of radiation|
- receiving electromagnetic radiation by interaction with the material, and transforming it to different form, which is usually heat (rise in temperature). the absorption process is dependent on t...
|acceptance angle in fiber optics|
The maximum incidence angle of a light ray which can be used for injecting light into a fiber core or waveguide
The magnitude of accessible laser (or other collateral) radiation of a specific wavelength or emission duration at a particular point as measured by appropriate methods and devices. also means rad...
|accessible emission limit|
The maximum accessible emission level limit (ael) permitted within a particular class. ael is determined as the product of accessible emission times the maximum permissible exposure (mpe) using th...
Laser radiation that can expose human eye or skin in normal usage.
Optical devices or setups with minimized chromatic aberrations
Optical modulators based on the acousto-optic effect
Collection of atoms or molecules which can be stimulated to a population inversion, and emit electromagnetic radiation in a stimulated emission.
|active mode locking|
A technique of mode locking, based on active modulation of the intracavity losses or the round-trip phase change
Recent advances in deformable mirror technology and laser guide stars allows most of the distortion produced by the atmosphere to be removed. this results in near diffraction-limited performance o...
|additive-pulse mode locking|
A technique for mode locking a laser, using a nonlinear interaction in an external resonator
|adiabatic soliton compression|
A pulse compression technique based on the adaptation of solitons to slowly varying propagation parameters
Literally, "without a focal length"; an optical system with its object and image point at infinity.
A laser (or other light source) used as a guide light. used coaxially with infrared or other invisible light, may also be a reduced level of the actual laser used for surgery or for other applicat...
Solid-state lasers based on alexandrite (cr3+:beal2o4) crystals
The sensitivity of a laser, an optical resonator or some other device with respect to misalignment
Laser systems containing solid-state devices only, in particular no discharge lamps or gas or dye lasers
|amplified spontaneous emission|
A process where spontaneously emitted radiation (luminescence) is amplified
Amplifiers consisting of several stages
Noise introduced to a signal in an amplifier device
Devices for amplifying the power of light beams
Light with an intensity noise below the shot noise level
|anamorphic prism pairs|
Prisms pairs for reshaping laser beams
- A unit of measure of wavelength equal to 10-10 meter, 0.1 nanometer, or 10-4 micrometer; no longer widely used nor recognized in the si system of units.
- Unit to define wavelength of...
Optical thin-film coatings for reducing reflections from surfaces
|apd avalanche photodetector|
The solid-state equivalent of a pmt, usually restricted to operation in the red, near-infrared and infrared part of the spectrum. for photon-counting applications, they are operated in the so-call...
|apparent visual angle|
The angular subtense of the source as calculated from the source size and distance from the eye. it is not the beam divergence of the source.
Antireflection coatings are used on optical components to suppress unwanted reflections.
|argon ion lasers|
Gas lasers based on light amplification in ionized argon in a gas discharge
- A gas laser in which argon ions are the active medium. this laser emits in the blue - green visible spectrum, primarily at 488 and 515 nm..
- A laser used in sealing blood vessels and...
|arrayed waveguide gratings|
Optical filter or multiplexer devices based on arrays of waveguides
Co2 laser beam delivery device consisting of a series of hollow tubes and mirrors interconnected in such a manner as to maintain alignment of the laser beam along the path of the arm.
Devices for measuring the intensity or field autocorrelation function of light, mostly used for determining the duration of ultrashort pulses
Photodiodes with internal signal amplification through an avalanche process
- The total energy imparted during exposure divided by the exposure duration.
- The average level of power in a signal that varies with time.
Movement of the eyelid or the head to avoid an exposure to a noxious stimulant, such as bright light. it can occur within 0.25 seconds and it includes the blink reflex time. aversion response acti...
A laser in which an axial flow of gas is maintained through the tube to replace those gas molecules depleted by the electrical discharge used to excite the gas molecules to the lasing.
A conical lens which, when followed by a conventional lens, can focus laser light to a ring shape.
The optical centerline for a lens system; the line passing through the center of curvature of the optical surfaces of a lens.
A measure of the nonlinear phase shift of light, e.g. in an amplifier
Pulses with a duration as short as possible with their optical spectrum
A hardware assembly containing an optical device, such as a mirror, capable of changing the direction of a laser beam; used to re-point the beam and used in "folded", compact laser syste...
A class of techniques for power scaling of laser sources by combining the outputs of multiple devices
The distance between diametrically opposed points in the cross section of a circular beam where the intensity is reduced by a factor of 1/e (0.368) of the peak level (for safety standards). the va...
- Angle of beam spread measured in radians or milliradians (1 milliradian = 3.4 minutes-of-arc or approximately 1 mil). for small angles where the cord is approximately equal to the arc, the bea...
An optical device that increases beam diameter while decreasing beam divergence (spread). in its simplest form, consists of two lenses, the first to diverge the beam and the second to re-collimate...
|beam parameter product|
Product of the beam radius in a focus and the far-field beam divergence