Photonics Dictionary: N

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...

The code used to describe the United States system of color telecasting.

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...

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...

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...

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...

In a laser diode, lateral motion of the beam center at the facet when the drive current is changed.

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.

A photocathode having a P-type semiconductor with a work function less than its bandgap. The photocathode can release a hundredfold increase of photoemission in the infrared region.

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...

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

Used in halftone screens to change the fundamental sampled spatial frequency of the halftoned picture, as well as varying the width of the pulse-modulated dots or gratings.

Also known as a gray body; a nonselective radiator is a thermal radiator that has a constant spectral emissivity with respect to wavelength throughout the spectral range being considered. The...

A radiometric device or system having uniform responsivity relative to all of the radiation parameters, or relative to one or more specified parameters, throughout all parameter intervals in which...

A filtering device that detects what is new in a scene of interest. Often compared to that of a temporal high pass filter, these filters will remove elements that appear repeatedly throughout an...

Expression of the nondimensional coefficient of the heat transfer in a convection process.

A symbol used to represent the refractive index. It is commonly used with a subscript to represent the wavelength of light.

In a semiconductor, the state created by the addition of a dopant that provides excess electrons.

A quadrivalent semiconductor material, with electrons as the majority charge carriers, that is formed by doping with donor atoms.

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...

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...

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...

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 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...

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...

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...

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...

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....

An optical pyrometer that is equipped with a narrow bandpass filter to transmit a limited number of wavelengths to the sensing device.

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...

The longest wavelengths of the ultraviolet region, nominally 300 to 400 nm.

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...

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....

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 (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....

The shortest wavelengths of the infrared region, nominally 0.75 to 3 µm.

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...

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...

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...

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...

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...