Glossary
N
- nanoscopy
- see super-resolution
- narrow-band filter
- see narrow-bandpass filter
- narrow-bandpass filter
- An optical filter that blocks light above and below a narrow range of wavelengths, with a range of ~10 nm commonly used.
- Synonyms: narrow-band filter
- See also: interference filter, bandpass filter, filter
- near-field scanning optical microscopy (NSOM)
- A microscopy technique that exceeds the diffraction limit by utilizing a narrow fiber probe positioned in the near field (proximal to the sample) and illumination with an evanescent wave. Resolution is typically limited by the size of the imaging aperture, which can be less than 10nm.
- Synonyms: scanning near-field microscope
- See also: super-resolution
- near-infrared DIC
- see infrared differential interference contrast
- near-infrared radiation (NIR)
- Radiation with a range of ~750 - 1400 nm, it is beyond the far-red range of the visible spectrum and at the beginning of the infrared. It is especially useful for biological imaging given the relatively low absorbance of biological tissue components in this range (the "near-infrared window").
- See also: infrared radiation, radiation, electromagnetic spectrum
- negative phase contrast
- see negative phase contrast microscopy
- negative phase contrast microscopy
- Phase contrast microscopy where the phase plate retards the un-diffracted light relative to the diffracted light by a quarter wavelength (λ/4). Since diffracted light is retarded by ~λ/4 through interaction with the object, the phase difference is eliminated and constructive interference occurs.
- Synonyms: negative phase contrast
- See also: phase, phase object, phase plate, phase difference, phase contrast microscopy, interference, positive phase contrast microscopy
- Nelsonian illumination
- see critical illumination
- neural net
- see artificial neural network
- neural network
- see artificial neural network
- neutral density filter (ND)
- A filter that reduces incoming light intensity of all wavelengths uniformly by a specified factor. The ND number is the denominator of a fraction and specifies the transmittance. For example, an ND4 filter transmits 1/4 (25%) of the incident light.
- See also: filter, transmittance
- Newton's colors
- see interference colors
- Nicol prism
- A component designed to convert incident light into linearly polarized light. It is made of birefringent calcite that has been cut and glued together to form an internal angled interface. The calcite separates incoming light into perpendicularly-polarized ordinary and extraordinary components. The ordinary ray is diverted away via total internal reflection at the glued interface, transmitting only the extraordinary component along the original lightpath.
- See also: polarized light, birefringence, polarized light microscopy
- Nikon advanced modulation contrast (NAMC)
- NAMC combines oblique illumination with a modulation contrast approach to visualize differences in phase across a sample. Differential interference contrast is unsuitable for observing cells in plastic dishes due to strain patterns and phase contrast suffers from halo and shade-off artifacts with large sample features. NAMC offers an alternative strategy that avoids these issues and is popular for in vitro fertilization (IVF) applications.
- See also: modulation contrast, brightfield, label-free, oblique illumination
- Nikon Bioimaging Lab (NBIL)
- Nikon BioImaging Labs provide contract research services for microscope-based imaging and analysis to the biotech, pharma, and larger research communities.
- Nikon emboss contrast
- A cost-effective optical contrasting technique which does not require expensive optical components. This technique utilizes brightfield observation and two contrast sliders to create pseudo-three dimensional glare-free images for thick specimens.
- Nipkow disk
- A disc with pinholes placed such that every revolution of the disc collectively scans the pinholes across the entire disc area with minimal overlap. This geometry is used for spinning disk microscopy to ensure that the whole field of view is excited and imaged.
- See also: confocal microscopy, spinning disk confocal microscopy, array-scanning confocal microscopy
- Nipkow disk confocal microscopy
- see spinning disk confocal microscopy
- NIR-DIC
- see infrared differential interference contrast
- NIS-Elements
- A software suite for microscopy image acquisition, analysis, and visualization. NIS-Elements offers a wide variety of functionality from basic microscope operation to custom, artificial intelligence (AI)-based acquisition and analysis routines.
- no cover glass objective (NCG)
- Objective lenses designed for applications where no coverslip is used , such as viewing blood smears. Typical objectives are designed to account for the refractive index and thickness of coverslips (coverslip correction), and will not produce the clearest images possible if no coverslip is present.
- See also: objective lens, coverslip, coverslip correction
- nodal points
- A ray of light traveling in the direction of the front nodal point will be refracted by the lens such that, when it emerges on the other side and refracted again, it will appear to be coming from the back nodal point.
- See also: cardinal points, focal point, principal points, geometric optics, ray tracing
- noise
- In the context of optical imaging, noise is any unwanted signal that degrades image quality. Different types of noise include Poisson noise (shot noise, photon noise), read noise, and dark noise.
- See also: averaging
- Nomarski differential interference contrast (DIC)
- Nomarski DIC is a variation of the technique that uses Nomarski prisms to accomplish the shearing of the ordinary and extraordinary rays from incident polarized light and their subsequent recombination. Bias compensation is performed by laterally translating one of the prisms relative to the other.
- See also: differential interference contrast, infrared differential interference contrast, polarized light, polarized light microscopy, Nomarski prism
- Nomarski prism
- A modified version of a Wollaston prism, it's made up of two birefringent quartz wedges glued together in order to split incident light into an ordinary and extraordinary ray.
- See also: Nomarski differential interference contrast, birefringence, polarized light ordinary ray, extraordinary ray
- non-descanned detection (NDD)
- A strategy for detecting emitted light immediately near a sample following excitation. It is preferred for single-point detection with multiphoton microscopy because it minimizes the number of optical components between the sample and detector, maximizing collection efficiency.
- See also: multiphoton microscopy, photomultiplier tube
- non-linear optics (NLO)
- A subfield focusing on non-linear behavior of light in a non-linear system. For example, two-photon absorption follows a non-linear curve dependent on excitation light intensity.
- See also: multiphoton microscopy, two-photon excitation, three-photon excitation, second harmonic generation microscopy, third harmonic generation microscopy, Raman scattering
- normal tube lens
- The lens that collects parallel, infinity-focused rays from the objective lens and focuses them to form the an image. Tube lens focal length varies by manufacturer (Nikon uses 200 mm).
- Synonyms: tube lens
- See also: infinity corrected objective, infinity optical system, tube lens focal length
- nosepiece
- The component that one or more objective lenses are mounted to. Different types include centering nosepieces, multi-position revolving nosepieces, and two-position sliding nosepieces.
- See also: centering nosepiece, revolving nosepiece, optical train, objective-locating nosepiece flange
- nosepiece flange
- see objective-locating nosepiece flange
- nosepiece locating surface
- see objective-locating nosepiece flange
- nosepiece turret
- see revolving nosepiece
- numerical aperture (NA)
- A dimensionless measure of light-gathering and resolving power, it accounts for the range of angles of light collected from an object by an objective lens and is given by the equation NA = nsin(alpha), where n is the refractive index of the immersion medium and alpha is the one-half angular aperture of the objective.
- Synonyms: object-side aperture
- See also: f-number, solid angle, angular aperture, resolution, aperture
- Nyquist criterion
- see useful magnification range
- Nyquist sampling
- The Nyquist-Shannon sampling theorem defines a minimum sampling rate required to observe a signal feature as twice the spatial or temporal frequency of that feature. For example, to properly image a periodic grating with 1 µm spacing, each pixel must cover 0.5 µm or less (projected in the object plane). In practice, a minimum 2.3X sampling rate is recommended.
- Synonyms: Nyquist-Shannon sampling
- See also: sampling, sampling rate
- Nyquist-Shannon sampling
- see Nyquist sampling
