Photonics Dictionary: N

A light filter that equally decreases the intensity of all wavelengths of light without altering the relative spectral distribution of the energy.

A strip or annulus of glass coated with a semitransparent material such as inconel. The coating thickness, and as a result its transmission, varies linearly as a function of distance. The neutral...

An additive color mixture that appears to have no hue.

In optics, the process of combining two lenses having equal and opposite powers to produce a result having no power.

Prediction based on observations of nuclear masses in the valley of stability that indicates the maximum number of electrons that will bind with a given number of protons in progressive order along...

The nondestructive analysis and recording of industrial components based on the absorption of relatively low-energy neutrons by material having low atomic numbers. The visible image formed by the...

The unit of force in the mks system that will give 1 kg of mass an acceleration of 1 m/s2.

The series of rings or bands formed when light beams reflected from two polished, adjacent surfaces, placed together with a thin film of air between them, interfere. By counting these bands from the...

A telescope with a concave paraboloidal objective mirror and a small plane (diagonal) mirror that reflects rays from the primary mirror laterally outside the tube where the image is viewed with an...

An instrument devised by Nichols and Hull for use in the measurement of radiation pressure. The device has two small silvered, glass mirrors that are suspended, in the way of a torsion balance, by a...

A prism invented by William Nicol in 1828 that is made of calcite, the end faces of which are ground to an angle of 68° between one vertical side and the end surface. The prism is cut diagonally...

A device that uses low-level visible radiation or infrared radiation to produce a visual image of a night scene. These devices may rely on the amplification of existing visible light by...

A device consisting of a disc with a spiral arrangement of holes that is used to convert visible patterns into electrical patterns. Light is reflected from the subject and focused through a vertical...

Unit of measurement of brightness (luminance) equal to one candela per square meter.

A pollution-measuring device used to detect the presence of nitric oxide regardless of other gases present. It utilizes the principle of laser magnetic resonance (LMR).

A nitrogen vacancy (NV) refers to a specific type of defect or impurity in a crystal lattice where a nitrogen atom replaces a carbon atom adjacent to a vacancy (an empty lattice site) in the diamond...

A monatomic, chemically inert gas such as argon, neon, krypton and xenon.

A television system used for seeing in the dark, particularly with the use of infrared rays.

A bench with instrumentation including a collimator, a microscope, positioners and a nodal slide used to rotate a lens about its second nodal point. The nodal bench is used to determine the cardinal...

Of all the rays passing through a lens from an off-axis object point to its corresponding image point, there is always one ray whose direction in the image space is equal to that in the object space....

The measurement of first- and higher order properties of a lens and its formed image, including effective focal length, back focal length, f number, aberrations, blur patterns, magnification and...

In a communications network, a point at which data are received or from which they are sent. Though the term often is used synonymously with workstation, interconnection points in a network also are...

The unwanted and unpredictable fluctuations that distort a received signal and hence tend to obscure the desired message. Noise disturbances, which may be generated in the devices of a communications...

Any noise or current fluctuation that prevents precise measurement of the signal current. Both dark current and signal current have random fluctuations that affect the arrival of pulses. Thermal...

In a thermal imaging system, the change in temperature that yields a signal-to-noise ratio of unity.

The amount of spatial noise detected equivalent to the output emission location of the giving source.

At a given modulation frequency, wavelength, and for a given effective noise bandwidth, the radiant power that produces a signal-to-noise ratio of 1 at the output of a given detector.

Also referred to as differential interference contrast (DIC) microscopy; Nomarski microscopy is a unique form of microscopy especially suited for the evaluation of surface quality and defects as well...

Zone of laser operation in which the direct, reflected or scattered light exceeds the laser's MPE and (by ANSI standards) requires the use of protective eyewear.

The calculated normal distance from a photon source at which harmful interaction with the incident light will occur. Interaction distance produces the effect of MPE (Maximum Permissable Exposure) on...