HALF-POWER POINT The value on either the leading or trailing edge of a laser
pulse at which the power is one-half of its maximum value.
HEAT SINK A substance or device used to dissipate or absorb unwanted heat energy.
HELIUM-NEON (HeNe) LASER A laser in which the active medium is a mixture of
helium and neon. Its wavelength is usually in the visible range. Used widely for
alignment, recording, printing, and measuring.
HERTZ (Hz) Unit of frequency in the International System of Units (SI), abbreviated
Hz; replaces cps for cycles per second.
HOLOGRAM A photographic film or plate containing interference patterns created
by the coherence of laser light. A three dimensional image may be reconstructed
from a hologram. Here are transmission, reflection or integral holograms.
