Nanometer (nm)

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.

Nanosecond

One billionth (10^-9) of a second. Longer than a picosecond or femtosecond, but shorter than a microsecond. Associated with Q-switched lasers.

Nd:Glass Laser

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.

Nd:YAG Laser

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.

Near Field

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.

Near Field Imaging

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.

Near Infrared

The region of the electromagnetic spectrum ranging from 700 nm to approximately 3 μm.

Neodymium (Nd)

The rare earth element that is the active element in Nd:YAG lasers and Nd:Glass lasers.

Noise

Unwanted minor currents or voltages in an electrical system.

Nominal Hazard Zone (NHZ)

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.

Nominal Ocular Hazard Distance (NOHD)

The axial beam distance from the laser where the exposure or irradiance falls below the applicable exposure limit.