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Nanometer
(nm)
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A
unit of length in the International System of Units (SI) equal
to one billionth of a meter. Abbreviated nm - a measure of
length. One nm equals 10-9 meter, and is the usual
measure of light wavelengths. Visible light ranges from about
400 nm in the purple to about 760 nm in the deep red.
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Nanosecond
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One
billionth (10-9) of a second. Longer than a picosecond
or femtosecond, but shorter than a microsecond. Associated
with Q-switched lasers.
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Nd:Glass
Laser
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A
solid-state laser of neodymium: glass offering high power
in short pulses. A Nd doped glass rod used as a laser medium
to produce 1064 nm light.
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Nd:YAG
Laser
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A
solid-state laser that uses a neodymium-doped yttrium aluminum
garnet (YAG) crystal as the lasing medium. The principal output
of this laser is at 1064nm.
Nd:YAG lasers are available in cw and pulsed configurations
and are used extensively in industrial applications for welding,
cutting, and laser marking.
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Near
Field
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In
terms of diffraction, a distance sufficiently close to the
diffracting aperture that the contribution from Fresnel diffraction
is significant. In terms of lasers, the distance from the
beam waist, extending to well beyond the Rayleigh range, wherein
wave-front curvature is significant.
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Near
Field Imaging
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A
solid-state laser imaging technique offering control of spot
size and hole geometry, adjustable working distance, uniform
energy distribution, and a wide range of spot sizes.
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Near
Infrared
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The
region of the electromagnetic spectrum ranging from 700 nm
to approximately 3 ¦Ìm.
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Neodymium
(Nd)
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The
rare earth element that is the active element in Nd:YAG lasers
and Nd:Glass lasers.
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Noise
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Unwanted
minor currents or voltages in an electrical system.
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Nominal
Hazard Zone (NHZ)
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The
nominal hazard zone describes the space within which the level
of the direct, reflected, or scattered radiation during normal
operation exceeds the applicable MPE. Exposure levels beyond
the boundary of the NHZ are below the appropriate MPE level.
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Nominal
Ocular Hazard Distance (NOHD)
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The
axial beam distance from the laser where the exposure or irradiance
falls below the applicable exposure limit.
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