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Definitions: N

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N, n
A symbol used to represent the refractive index. It is commonly used with a subscript to represent the wavelength of light.
N-type conductivity
In a semiconductor, the state created by the addition of a dopant that provides excess electrons.
N-type material
A quadrivalent semiconductor material, with electrons as the majority charge carriers, that is formed by doping with donor atoms.
nadir
In a remote sensing system, nadir refers to the point on the ground located vertically below the center of the system. In astronomy, the nadir is the vertical direction that points towards the force...
Nagel anomaloscope -> color perception test equipment
Equipment for testing an observer's color vision. Some tests require the identification or ordering of colored samples. The commercially available examples include: the Ishihara plates, on which...
nano
An SI prefix meaning one billionth (10-9). Nano can also be used to indicate the study of atoms, molecules and other structures and particles on the nanometer scale. Nano-optics (also referred to as...
nanoimprint lithography
Nanoimprint lithography (NIL) is a nanolithography technique used for fabricating nanoscale patterns on a substrate. It is a high-resolution, high-throughput process that involves the mechanical...
nanoLED
An LED (light-emitting diode) is a semiconductor device that emits light when an electric current passes through it. LEDs are commonly used for lighting, displays, and indicators. A NanoLED is on the...
nanometer
A unit of length in the metric system equal to 10-9 meters. It formerly was called a millimicron.
nanoparticle
A small object that behaves as a whole unit or entity in terms of it's transport and it's properties, as opposed to an individual molecule which on it's own is not considered a nanoparticle.....
nanoparticle photonic resonator absorption microscopy
Nanoparticle photonic resonator absorption microscopy is a microscopy technique that combines the principles of photonic resonators and nanoparticle imaging to visualize and study biological samples...
nanophotonics
Nanophotonics is a branch of science and technology that explores the behavior of light on the nanometer scale, typically at dimensions smaller than the wavelength of light. It involves the study and...
nanoplasmonics
Nanoplasmonics is a branch of nanophotonics that focuses on the study and manipulation of optical phenomena at the nanoscale using plasmonic materials and structures. Plasmonics deals with the...
nanopositioning
Nanopositioning refers to the precise and controlled movement or manipulation of objects or components at the nanometer scale. This technology enables the positioning of objects with extremely high...
nanostructured glass
A unique glass made up of nano-structured materials to create millimeter sized monolithic glass space-variant polarization converters which ultimately alter the way light propagates through and is...
nanotechnology
The use of atoms, molecules and molecular-scale structures to enhance existing technology and develop new materials and devices. The goal of this technology is to manipulate atomic and molecular...
nanotube
A nanotube, also known as a nanotubule or simply a tube-like structure, is a nanoscale cylindrical structure composed of various materials, including carbon, boron nitride, or other compounds....
narcissus
A defect in infrared systems that appears as a dark circular area on a displayed image, caused by radiation reflecting into a detector. It can be reduced by low-reflective coatings or by altering the...
narrow bandpass filter -> interference filter
A filter that controls the spectral composition of transmitted energy partially by the effects of interference. Frequently, these filters are made up of thin layers of metals and dielectrics,...
narrow-angle dark-field illumination
An imaging system designed to highlight small deviations in a planar reflective object such as a mirror. The system can be used to detect minute flaws or to image faint marks that are made in the...
narrowband pyrometer
An optical pyrometer that is equipped with a narrow bandpass filter to transmit a limited number of wavelengths to the sensing device.
National Television Systems Committee
The code used to describe the United States system of color telecasting.
native fluorescence
The light emitted from tissues without the use of fluorescent dyes as markers. Because cancerous tissues and normal tissues have differing emission spectra, the native fluorescence can be used to...
Nd:glass -> neodymium glass
Glass containing small quantities of neodymium oxide that is used as a filter plate in color television or as a lasing medium (Nd:glass) in solid-state lasers.
Nd:YAG -> neodymium:YAG
Literally, neodymium:yttrium-aluminum-garnet. A cylindrical rod of yttrium-aluminum-garnet doped with neodymium that is the active medium of the Nd:YAG laser, a highly serviceable solid-state device...
Nd:YAG laser
Nd:YAG laser refers to a solid-state laser that utilizes neodymium-doped yttrium aluminum garnet (Nd:Y3Al5O12) as the gain medium. This type of laser emits light at a wavelength of 1064 nm in the...
near point of eye
The closest distance to which the eye can focus on an object, normally taken to be 250 mm. The near point varies with age.
near ultraviolet
The longest wavelengths of the ultraviolet region, nominally 300 to 400 nm.
near-field diffraction -> Fresnel diffraction
1. Also known as near-field diffraction. The field of radiation sent through an aperture in an absorbing screen at large distances as compared with the wavelength and the dimensions of the aperture,...
near-field holography
A lithography method that allows the transfer of fine-pitch gratings from a phase mask into photoresist. The exposure takes place with the light coming under an oblique angle to the mask. The...
near-field region
The area closest to an aperture or source where the diffraction pattern differs substantially from that observed at an infinite distance, or more specifically, the far field. Also referred to as the...
near-field scanning optical microscope
A scanning probe microscope that analyzes the surface of a specimen by recording the intensity of light as it is focused through a pipette and raster scanned across the specimen at a distance less...
near-field scanning
A measurement technique used to determine the spatial distribution profile of an electrical or optical quantity of interest which is provided by multiple scans within the near-field region of a...
near-field walk
In a laser diode, lateral motion of the beam center at the facet when the drive current is changed.
near-infrared camera
A near-infrared (NIR) camera is an imaging device designed to capture images in the near-infrared region of the electromagnetic spectrum. The near-infrared spectrum typically extends from about 700...
near-infrared spectrometer
A near-infrared (NIR) spectrometer is an analytical instrument used to measure the absorption, transmission, or reflection of light in the near-infrared region of the electromagnetic spectrum....
near-infrared spectroscopy cerebral oximetry
A monitoring technique used to measure the oxygen saturation levels in the brains of patients, commonly in operating room and neonatal intensive care unit settings. The technique, which is based on...
near-infrared spectroscopy
Near-infrared spectroscopy (NIRS) is a non-invasive analytical technique that uses the near-infrared region of the electromagnetic spectrum to study the absorption of light by molecules in a sample....
near-infrared
The shortest wavelengths of the infrared region, nominally 0.75 to 3 µm.
near-ultraviolet light source
A light source, such as the sun or an incandescent lamp, that freely penetrates ordinary glass bulbs and emits in the near-ultraviolet (wavelengths ranging from about 300 to 400 nm). A mercury vapor...
nearest neighbor
A resampling and interpolation method that uses only the value of the nearest neighbor pixel, while not considering values from any other neighboring pixels from the source image to determine the...
negative absorption
Amplification; the result of the excess of stimulated radiation over absorbed radiation.
negative carrier
The structure that holds the photographic negative in a proper position that is both flat and parallel to the lens plane, as well as being placed in a fixed position that is the right distance from...
negative crystal
A uniaxial, birefringent crystal such as calcite or ruby in which the velocity of the extraordinary ray surpasses that of the ordinary ray. This can also be defined as the index of refraction of the...
negative dielectric anisotropy
State typically studied in liquid crystals in which the dielectric coefficient parallel to the director is less than the dielectric coefficient perpendicular to the director.
negative ghost
A ghost image that has the reverse lightness relations of the original image. This phenomenon is a common optical illusion that takes place in the human visual system, following long exposures to an...
negative glow
In a cold-cathode tube, the luminance between the cathode dark space and the Faraday dark space. In a vacuum tube, the luminance between the Crookes dark space and the Faraday dark space.
negative lens -> diverging lens
A diverging lens is a type of lens that causes parallel rays of light to spread out or diverge. It is thinner in the center than at the edges and is commonly referred to as a concave lens. The most...
negative meniscus lens -> divergent-meniscus lens
A lens with one surface convex and the other concave, the latter having the greater curvature. It also is known as a diverging meniscus lens.
negative stereoscopic image
When a stereo pair of images is switched so that the right eye sees the left image and the left eye the right, the stereo image perceived will be reversed in terms of relative object depth.

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