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dark low low phase contrast objective (DLL): An phase contrast objective where phase objects appear dark against a very light gray background.; See also: phase contrast, objective lens
dark low phase contrast objective (DL): An phase contrast objective where phase objects appear dark against a light gray background.; See also: phase contrast, objective lens
dark medium phase contrast objective (DM): An phase contrast objective where phase objects appear dark against a medium gray background.; See also: phase contrast, objective lens
darkfield: Contrasting techniques that involve the observation of the object against a dark background. This term is also used to specifically refer to illumination with light at such a high angle that only light deviated by the object can be collected.; See also: darkfield condenser, darkfield stop, contrasting technique
darkfield condenser: A specialized high numerical aperture (NA) condenser for darkfield imaging that illuminates the object exclusively with high-angle light. Darkfield condensers are usually either of a cardioid condenser design or utilize a darkfield stop to block low-angle light.; See also: darkfield, darkfield stop, cardioid condenser, condenser
darkfield stop: An aperture mask located in the front focal plane of a darkfield condenser consisting of a central circular disk that blocks all but high angle (high frequency) light, resulting in a hollow cone of illumination.; See also: darkfield, darkfield condenser, cardioid condenser, condenser
dead pixel: A defective pixel from which no signal is read - the opposite of a hot pixel.; See also: hot pixel, pixel, area detector, camera
deconvolution: A class of computational approaches for performing the task of image restoration using knowledge of the image formation process and the system's point-spread function (PSF).; Synonyms: image restoration; See also: computational microscopy
deep learning (DL): In the field of artificial intelligence (AI), deep learning (DL) is a type of machine learning (ML) that uses algorithmic structures known as artificial neural networks (ANNs) with more than three layers to address complex tasks. DL methods usually requires more training data than other approaches.; See also: artificial intelligence, training (machine learning)
depth of field: The axial (Z) distance about the focal plane through which a point source can be located and form a reasonably in-focus image.; Synonyms: object space; See also: depth of focus
depth of focus: The axial (Z) distance about a conjugate image plane where a detector can be located and form a reasonably in-focus image of a point source.; See also: depth of field
descanning: In the context of a scanning microscope, this refers to detected light retracing the scanning optics such that it will be maintain the same incidence on the detector (and confocal pinhole) regardless of scan position.; See also: confocal microscopy, point-scanning confocal microscopy, multiphoton microscopy
detection path: The part of the optical train directing light detected from the object towards the observer or detector.; See also: optical train, illumination path
detection waveband: The range of wavelengths detected in a given channel.; See also: channel, emission filter
detector: A device that detects a signal of interest. In optical imaging, a detector with multiple detecting elements (pixels) is known as an area detector. A digital camera is a type of area detector. A detector may only have a single sensitive element, as is the case with a photomultiplier tube.; See also: area detector, photomultiplier tube, charge coupled device, electron multiplying charge coupled device, scientific complementary metal-oxide-semiconductor detector
diaphragm: see stop
diascopic illumination: see transmitted light illumination (diascopic illumination)
dichroic: see shortpass filter
dichroic filter: see interference filter
dichroic mirror: An optical component that strongly reflects light of one waveband and strongly transmits light of another, usually with a sharp cut-on.; Synonyms: dichromatic mirror
dichromatic mirror: see dichroic mirror
differential interference contrast (DIC): A contrasting technique that utilizes illumination with polarized light that has been sheared into parallel ordinary and extraordinary rays, with differences in optical path length between these rays manifesting as constructive and destructive interference once recombined, creating contrast.; See also: contrasting technique, birefringence, interference, polarized light, Nomarski differential interference contrast
diffracted light: Light that when diffracted by an object is collected by the system to create an image of the object.; See also: diffraction, diffraction pattern, diffraction limit
diffraction: The apparent bending of light waves at an edge or through an aperture due to interference effects. Diffraction is especially apparent with opening sizes on the order of a single wavelength, resulting in interference patterns.; See also: diffraction pattern, diffracted light
diffraction barrier: see diffraction limit
diffraction grating: A periodic structure used to diffract light, dispersing it into its constituent wavelengths.; See also: diffraction, diffraction pattern
diffraction limit: The limit of direct resolving power in optical microscopy imposed by the diffraction of light by a finite pupil.; Synonyms: diffraction limit of resolving power, diffraction barrier; See also: diffraction, diffraction pattern, diffracted light
diffraction limit of resolving power: see diffraction limit
diffraction pattern: Due to the finite pupil of microscope optics, only part of the wavefront emanating from the object can be sampled, resulting in diffraction and the formation of a diffraction pattern in the back focal plane.; See also: diffraction, diffracted light, diffraction limit
diffuser: An optical component typically made of a translucent material which scatters light, producing non-collimated "soft light" with low coherence.; Synonyms: light diffuser, optical diffuser; See also: scattering, filter, coherence, collimation
digital holographic microscopy (DHM): A type of quantitative phase microscopy that uses a laser split into two beams - the illumination and reference beams. These wavefronts interfere to create a hologram at the detector, which can be recorded and used to reconstruct an image.; See also: quantitative phase microscopy
digital image: An image that is digitally recorded and composed of discrete pixels with finite values.; See also: camera, pixel, image
digital micromirror device (DMD): An array of individually addressable microscopic mirrors with adjustable deflection angle, allowing users to precisely pattern reflected light.; See also: spatial light modulator
digital pathology: The field concerned with the digitization of pathology samples, often using techniques such as whole slide imaging (WSI) to create complete digital representations.; See also: whole slide imaging
Digital Sight series cameras: The long-running series of digital cameras produced by Nikon for research, clinical, and educational microscopy applications.
digital zoom: Enlarging the view of an image on the display without applying any real/optical zoom and without any gain in resolution.
digitally enhanced contrast: The use of digital image processing tools to artificially adjust the apparent contrast in the image. For grayscale images, this involves a simple remapping of pixel intensity values.
diopter: The reciprocal focal length of a lens or curved mirror, used to express its optical power.
dioptric: A term used to describe optical systems composed of lenses and functioning via refraction.; See also: catoptric, catadioptric
direct light: Light that continues undeviated through the object and is collected by the objective lens. It also refers to light that is specularly reflected and recollected by the objective in episcopic systems.; Synonyms: zero order light, 0th order light; See also: diffracted light
disk of confusion: see circle of least confusion
dispersion: A phenomenon arising from the wavelength-dependence of refractive index in media outside of a vacuum. This is what causes the component wavelengths of white light to separate when refracted by a prism.; Synonyms: optical dispersion; See also: dispersion curve, dispersion staining, refractive index
dispersion curve: A plot of the refractive index of a material at different wavelengths.; Synonyms: dispersion relation; See also: dispersion, dispersion staining, refractive index
dispersion relation: see dispersion curve
dispersion staining (DS): An analytical optical staining technique for probing the dispersive properties of a material by immersing it in a medium with a known dispersion curve and using color as a readout.; See also: dispersion, dispersion curve, dispersion staining objective
dispersion staining objective: Objective lenses intended for performing the dispersion staining (DS) technique. Nikon offers dedicated dispersion staining objective lenses based on the phase contrast version of the technique.; See also: dispersion, dispersion curve, dispersion staining
dissecting microscope: An optical microscope or stereomicroscope principally used to assist with dissection. A long working distance and low magnification are especially useful for this purpose.; See also: stereomicroscope
distortion: A geometric third-order optical aberration where lateral magnification either increases (pincushion distortion) or decreases (barrel distortion) with increasing distance from the optic axis.; See also: pincushion distortion, barrel distortion, aberration
DNA-PAINT: An approach to super-resolution single molecule localization microscopy (SMLM) using transiently hybridizing short single-strand oligonucleotides for labeling and fluorescence detection of single molecules.; See also: single molecule localization microscopy, photoactivated localization microscopy, stochastic optical reconstruction microscopy, super-resolution
double refraction: see birefringence
dry objective: An objective lens that is not designed for use with an applied immersion medium such as water or oil - air is the immersion medium.; Synonyms: air objective; See also: objective lens