18WuD2x

lapping • laser diode 399
lapping Fine-tuning quartz crystal plates by moving
them over a flat plate coated with a liquid
abrasive.
laptop computer See NOTEBOOK COMPUTER.
lap winding In a motor or generator armature, a
winding in which the opposite ends of each coil
are connected to the adjoining segments of the
commutator.
lap wrap 1. A form of asbestos cloth wire insulation.
2. A method of wrapping with electrical tape,
in which there is considerable overlap among the
turns of the tape.
large calorie See KILOGRAM-CALORIE.
large loop antenna A single-turn open or closed
loop, usually having a circumference of 0.5 wavelength
or 1 wavelength. With a half-wavelength
open or closed loop, maximum radiation occurs
in the plane of the loop. A full-wavelength closed
loop exhibits maximum radiation and response
along the axis. This type of antenna can be used
for wireless transmitting and receiving applications.
Either the open or the closed halfwavelength
loop exhibits a slight power loss
relative to a dipole, but the full-wavelength loop
shows a small gain over a dipole in its favored
directions. Compare SMALL LOOP ANTENNA.
large-scale integration Abbreviation, LSI. The inclusion
of more than 100 transistors, performing
various individual, but interrelated circuit functions,
on a single integrated-circuit chip.
large signal A relatively high-amplitude signal that
traverses so large a part of the operating characteristic
of a device that nonlinear portions of the
characteristic are usually encountered. Compare
SMALL SIGNAL.
large-signal analysis The rigorous study of circuits
and devices that process large signals.
large-signal component 1. A coefficient or parameter
such as amplification, transconductance, or
dynamic resistance, measured under conditions
of large-signal operation. Also see LARGE SIGNAL
and LARGE-SIGNAL EQUIVALENT CIRCUIT. 2. A
device designed for operation at high signal
levels.
large-signal equivalent circuit For a given transistor
circuit, the equivalent circuit at high signal
levels (i.e., at amplitudes approaching saturation
and cutoff levels). Also see EQUIVALENT CIR-
CUIT.
large-signal operation The use of a circuit or device
at signal levels sufficiently high so that nonlinear
portions of the characteristic are usually
encountered. Compare SMALL-SIGNAL OPERA-
TION.
large-signal transistor See POWER TRANSISTOR.
large-signal voltage gain In an integrated-circuit
amplifier, the voltage gain under open-loop conditions,
determined as the difference in the output
voltage divided by the difference in the input voltage.
It is usually specified in volts per millivolt or
volts per microvolt.
Larmor orbit The path followed by a charged particle
in a constant magnetic field. Because of interaction
between the external field and the field
generated by the particle, the charged particle
travels in a circular path.
laryngaphone See THROAT MICROPHONE.
LASCR Abbreviation of LIGHT-ACTIVATED SILI-
CON-CONTROLLED RECTIFIER.
LASCS Abbreviation of LIGHT-ACTIVATED SILI-
CON-CONTROLLED SWITCH.
lase To emit coherent electromagnetic energy in
the visible-light spectrum. See LASER.
laser Acronym for light amplification by stimulated
emission of radiation. A device that produces coherent
radiation in the visible-light range, that is,
between 750 and 390 nanometers (one nanometer
is 10 -9 meter). Some devices that produce coherent
radiation in the infrared, ultraviolet, or
X-ray parts of the spectrum are also referred to as
lasers. Lasers can be either continuous or pulsed,
and are characterized by coherent, monochromatic
emissions. The peak intensity ranges from
a few microwatts to many megawatts.
Laser
beam
Ruby rod
Flash
tube
Power supply
laser
Silvered
end
laser beam The radiation from a laser—especially
if the divergence is very low, that is, the rays are
almost perfectly parallel, resulting in minimal divergence.
laser-beam communication A form of coherent
infrared or optical communication in which a
laser beam is the link between transmitting and
receiving stations. Also see LASER, LASER
DIODE, and LIGHT-BEAM COMMUNICATION.
laser capacitor An energy-storage capacitor used
to discharge-fire the exciter lamp of a laser. Also
see LASER.
laser cavity An optical-resonant cavity that results
in the emission of coherent light.
laser cutting A method of using a laser for severing
materials.
laser diode A special form of semiconductor lightemitting
diode (LED), usually of the galliumarsenide
type, that emits coherent light when a
voltage is applied to its terminals. Also see LASER.