Synonym optical switch.

A semiconductor device that emits incoherent optical radiation when biased in the forward direction.

See optical fiber.

The brightness of an area subjectively judged relative to the brightness of a similarly illuminated area that appears to be white or highly transmitting. [After SMPTE]

In a lightning protection subsystem, the conductor connecting the air terminal or overhead ground wire to the earth electrode subsystem.

All of the components used to protect a facility from the effects of lightning.
Note: The lightning protection subsystem includes air terminals, lightning down- conductors, the earth electrode subsystem, air gaps, arresters, and their interconnections.

A simplified version of the X.500 standard, which version consists of a set of protocols developed for accessing information directories. [After Bahorsky]

A form of short-term communications security applied to the electromagnetic or acoustic transmission of unclassified information that warrants a degree of protection against simple analysis and easy exploitation but that does not warrant protection to the extent needed for security of classified information.

Equipment that provides limited security for unclassified voice communications.

A device in which the voltage or some other characteristic of the output signal is automatically prevented from exceeding a specified value.