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Scintillation

Term 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 or latch).

Self-contained lasers

Include the laser, optics, and power supply in a single case.

Semiconductor laser

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

Separated geometry lasers

Offer added flexibility by housing the diode and lens in their own laser head assembly, separate from the power supply. This configuration gives users a choice among laser head sizes and makes incorporation into an application easier.

Service

Performance of adjustments, repair, or procedures on a non-routine basis. Required to return the equipment to its intended state.

Single mode

Laser emission in a single transverse mode, or laser emission at a single primary wavelength.

Solid angle

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

Source

Either a laser or laser-illuminated reflecting surface, i.e., source of light. A physical source of radiation such as a laser diode.

Source size

The physical size of a source of radiation, such as from a laser diode. Also see emitter size.

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 diameter 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 frequency, the second atom will be stimulated to emit a photon.

Superpulse

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