Technical Center: Laser Glossary of Terms

Scanning Laser

A laser having a time-varying direction, origin, or pattern of propagation with respect to a stationary frame of reference.

Scintillation

This term is used to describe the rapid changes in irradiance levels in a cross section of a laser beam produced by atmospheric turbulence.

Secured Enclosure

An enclosure to which casual access is impeded by an appropriate means (e.g., door secured by lock, magnetically or electrically operated, latch, or by screws).

Semiconductor Laser

A type of laser which produces its output from semiconductor materials such as GaAs.

Service

Performance of adjustments, repair, or procedures on a nonroutine basis, required to return the equipment to its intended state.

Solid Angle

The ratio of the area on the surface of a sphere to the square of the radius of that sphere. It is expressed in steradians (sr).

Source

The term "source" means either laser or laser-illuminated reflecting surface, i.e., source of light.

Spectral Response

The response of a device or material to monochromatic light as a function of wavelength.

Specular Reflection

A mirror-like reflection.

Spontaneous Emission

Decay of an excited atom to a ground or resting state by the random emission of one photon. The decay is determined by the lifetime of the excited state.

Spot Size

The mathematical measurement of the radius of the laser beam.

Stability

The ability of a laser system to resist changes in its operating characteristics. Temperature, electrical, dimensional, and power stability are included.

Steradian (sr)

The unit of measure for a solid angle.

Stimulated Emission

When an atom, ion, or molecule capable of lasing is excited to a higher energy level by an electric charge or other means, it will spontaneously emit a photon as it decays to the normal ground state. If that photon passes near another atom of the same energy, the second atom will be stimulated to emit a photon.

Superpulse

Electronic pulsing of the laser driving circuit to produce a pulsed output (250-1000 times per second), with peak powers per pulse higher than the maximum attainable in the continuous wave mode. Average powers of superpulse are always lower than the maximum in continuous wave. Process often used on CO2 surgical lasers.