Glossary

T

temporal resolution
The minimal time interval between imaging frames in a timelapse acquisition running at continuous speed.
See also: resolution, sampling rate, Nyquist sampling
temporally coherent illumination
A wavefront of illumination that does not interfere with itself across various points in time - it maintains a more-or-less constant phase relationship across time and space. It is quantified as the coherence length.
See also: coherence, spatially coherent illumination, phase, interference
test object
A microscope specimen (object) with features that are used as a standard for assessing the performance of an optical system. An historical example is the spacing of frustules on diatoms.
thin-film filter
see interference filter
third harmonic generation microscopy (THG)
An non-linear optics methodology where three lower energy photons are up-converted to one-third the wavelength (i.e. triple the frequency) of an excitation laser. This phenomenon isn't restricted to non-centrosymmetric materials (as with second harmonic generation), but is strongest at material interfaces.
Synonyms: frequency tripling
See also: second harmonic generation microscopy, non-linear optics
three-photon excitation (3PE)
Three-photon excitation refers to the excitation of a system by three photons arriving simultaneously and via virtual energy levels, commonly used in multiphoton microscopy. The three-photon excitation wavelength tends to be roughly triple the usual one-photon excitation wavelength.
See also: multiphoton excitation, one-photon excitation, two-photon excitation, multiphoton microscopy
tiling
see image stitching
time lapse imaging
An imaging methodology where a sequence of images are taken of the same object (typically a live specimen) at a regular interval, and biological or chemical changes are observed and analyzed.
tissue clearing
A sample preparation methodology that imparts a specimen with a high degree of optical transparency. This is typically achieved by homogenizing the refractive indexes of specimen features.
Synonyms: optical clearing
See also: refractive index, expansion microscopy
tissue culture
The growth in an artificial medium of cells derived from living tissue.
Synonyms: cell culture
total internal reflection fluorescence microscopy (TIRF)
A microscopy technique which harnesses the principles of total internal reflection (TIR), where incident fluorescent light at high enough angles reflects off of the interface between the coverslip and the immersion media/specimen, but also resulting in an evanescent wave shallowly penetrating the sample. This provides a very high degree of optical sectioning about the interface.
See also: fluorescence, fluorescence microscopy, optical sectioning
total magnification
The magnification of the objective lens, multiplied by that of any other components in the optical train when forming a real image. For example, a microscope with a 60X objective lens, 10X eyepiece, and 1.5X relay lens provides a total magnification of 900X.
Synonyms: total magnification of a microscope
total magnification of a microscope
see total magnification
training (machine learning)
A computational process where a neural network is provided with example inputs and expected outputs, and its weights are adjusted in an iterative process to maximize accuracy.
See also: artificial intelligence, deep learning
transmittance
The percentage of light that successfully passes through (is transmitted) by a given sample. Intensity is often lost to effects such as absorption, reflection, and scattering.
See also: objective lens spectral transmittance by design, neutral density filter
transmitted light illumination (diascopic illumination)
Microscope techniques where illumination light transmitted through the object is collected and detected.
Synonyms: diascopic illumination
See also: epi-illumination
transverse magnification
see lateral magnification
trinocular tube
A microscope observation tube where three optical paths are available: typically two for each eye, and one for a camera.
See also: observation tube, monocular tube, binocular tube, quadrocular tube
tube
Section of microscope between the objective lens and the eyepiece, with the principal component being the body tube found in the microscope base.
See also: observation tube, body tube, intermediate tube
tube factor
The total product of the individual factors of the intermediate lenses in a tube.
See also: magnification, total magnification
tube length
Distances between different planes and surfaces in a tube.
See also: tube
tube lens
see normal tube lens
tube lens focal distance
see tube lens focal length
tube lens focal length
The focal length of the tube lens, which focuses light gathered by an infinity-corrected objective lens to form an image. Longer tube lens focal lengths allow for additional optical components to be introduced to the light path.
Synonyms: tube lens focal distance
See also: tube lens, focal length, infinity optical system
tungsten-halogen lamp
see halogen lamp
two-beam interference
The superposition and interference of two similar waves according to the superposition principle.
See also: interference, superposition principle
two-photon excitation (2PE)
Two-photon excitation refers to the excitation of a system by two photons arriving simultaneously and via a virtual energy level, commonly used in multiphoton microscopy. The two-photon excitation wavelength tends to be roughly twice the usual one-photon excitation wavelength.
See also: multiphoton excitation, one-photon excitation, three-photon excitation, multiphoton microscopy