Glossary
O
- object
- A physical feature in the object plane that is the subject of imaging. There are a number of mechanisms by which contrast can be generated through the interaction of the object with light.
- Synonyms: sample
- See also: object plane, optical train, field plane, specimen
- object field
- see field of view
- object marker
- A component that can be used to mark regions of interest directly onto a cover slip.
- object plane
- The plane where objects are observed within a sample. This plane belongs to the set of conjugate field planes.
- Synonyms: sample plane, specimen plane
- See also: conjugate planes, field plane, field of view
- object space
- see depth of field
- object to primary image distance
- The distance between the object plane and primary image plane measured along the optical path.
- object-side aperture
- see numerical aperture
- objective
- see violet corrected objective
- objective field number
- see objective lens field number
- objective flange
- Locating flange (surface) on an objective lens for mounting to the nosepiece. It is coincident with the objective-locating nosepiece flange.
- Synonyms: objective shoulder, locating flange of the objective, objective locating surface
- See also: objective lens, objective-locating nosepiece flange, locating flange
- objective lens
- The optical component that collects light from the sample that is used to form an image. Modern objective lenses are multi-lens systems designed to correct for various optical aberrations. Objective lenses are designed for use with a variety of immersion media, depending on the application.
- See also: aberration, optical train, objective lens color codes, objective spectral transmittance by design
- objective lens color codes
- Colors painted on the objective lens body to indicate the specified magnification and immersion media. Some common colors are 4x - red, 10x - yellow, 20x - green, 40x - light blue, 60x - dark blue, 100x - white. Immersion color codes are painted between the magnification color and the tip of the objective lens. Some common immersion color codes are oil - black, water - white, and special (such as silicone oil) - red.
- See also: objective lens, magnification, immersion medium
- objective lens field number (OFN)
- Diameter of the view field (in millimeters) measured at the intermediate image plane.
- Synonyms: objective field number
- See also: field number, eyepiece field number, field of view
- objective lens spectral transmittance by design
- see transmittance
- objective locating surface
- see objective flange
- objective parfocal distance
- Distance between the object plane and the objective flange.
- See also: parfocality
- objective screw thread
- The metallic threading on a microscope objective used to secure it to the nosepiece.
- objective shoulder
- see objective flange
- objective spectral transmittance by design (OSTD)
- The transmittance of light through an objective lens across the spectrum of light, accounting for absorption and reflection of all component lenses.
- See also: objective lens, transmittance
- objective-locating nosepiece flange
- Locating flange (surface) on the nosepiece where an objective lens is mounted, it is coincident with the objective flange.
- Synonyms: nosepiece flange, nosepiece locating surface, objective-locating nosepiece surface
- See also: nosepiece, body tube, locating flange, objective flange
- objective-locating nosepiece surface
- see objective-locating nosepiece flange
- objectives
- see fluorite objective
- oblique illumination
- A technique in which the sample is illuminated by angled light, thus shifting the zeroth order of diffracted light towards the edge of the objective aperture and higher-order diffraction orders toward the center of the objective. In effect, this enhances contrast in a directional manner and observed objects take on a shadowed, somewhat 3D appearance.
- See also: darkfield, stereomicroscope, Nikon advanced modulation contrast
- observation tube
- The tube assembly where the light path passes to the eyepiece oculars or observation camera.
- Synonyms: viewing tube
- See also: optical train, binocular tube, trinocular tube, quadrocular tube, monocular tube
- ocular
- see eyepiece
- oil immersion objective
- Oil immersion objectives typically have higher numerical aperture and shorter working distance compared to other, lower refractive index (RI), immersion types. Immersion oil generally has an RI of ~1.51 and is best-suited for observing thin samples mounted in a medium of similar RI.
- See also: refractive index, spherical aberration, immersion objective, working distance, water immersion objective
- one-photon excitation (1PE)
- One-photon excitation refers to the excitation of a system by a single photon as in widefield or confocal fluorescence microscopy. In contrast, multiphoton microscopy relies on two- or three-photon excitation.
- See also: multiphoton excitation, two-photon excitation, three-photon excitation, multiphoton microscopy
- optic axis
- The direction of propagation in a birefringent material in which an incident ray does not experience birefringence. A uniaxial crystal has a single optic axis while a biaxial crystal has two optic axes. The "optic axis" is a different concept than the "optical axis."
- See also: birefringence, ordinary ray, extraordinary ray, polarized light, wave plate, compensator
- optical aberration
- see aberration
- optical axis
- The axis that passes perpendicularly through the center of the object plane, objective lens, and subsequent optical system, defining the center of the optical path. The "optical axis" is unrelated to the "optic axis," the latter being a property of birefringent materials.
- See also: ray tracing, geometric optics
- optical clearing
- see tissue clearing
- optical coating
- Coatings are applied to the surface of optical lenses designed to minimize reflection and maximize transmission.
- See also: objective lens
- optical coherence microscopy (OCM)
- Techniques based on optical coherence tomography (OCT) that realize higher lateral resolution than usual. OCM techniques often use higher numerical aperture objectives than OCT, and many are based on a point-scanning confocal type of configuration.
- See also: optical coherence tomography, interferometry, interference, point-scanning confocal microscopy
- optical coherence tomography (OCT)
- A label-free coherent imaging technique that uses interferometry with broadband partially coherent light to help form an image of the object via back-scattering. It is typically capable of penetrating ~1-2 mm into tissue and with resolution measured in the tens of micrometers.
- Synonyms: optical low-coherence reflectometry
- See also: optical coherence microscopy, interferometry, interference
- optical diffraction tomography (ODT)
- A label-free coherent imaging technique that uses interferometry with a monochromatic laser light source to probe the 3D distribution of refractive indices in an object. A type of quantitative phase microscopy, it relies on the creation and processing of holographs from different illumination angles.
- See also: quantitative phase microscopy, coherent imaging system, interferometry, interference
- optical diffuser
- see diffuser
- optical dispersion
- see dispersion
- optical indicatrix
- see index ellipsoid
- optical interfacing dimensions of the microscope
- Dimensions regarding the locations of image-forming parts of the microscope, such as focal lengths, screw threads, and diameters, from various locating flanges.
- See also: locating flange
- optical low-coherence reflectometry
- see optical coherence tomography
- optical microscope
- see light microscope
- optical path difference
- see optical path length difference
- optical path length (OPL)
- The distance that light would travel through a vacuum to maintain an equivalent phase with light traveling through some medium. For example, light passing through a cell experiences a longer optical path length than light that does not.
- See also: optical path length difference
- optical path length difference (OPD)
- The difference in optical path length between two paths, it's important for determining phase differences.
- Synonyms: optical path difference
- See also: optical path length
- optical rotation
- The rotation that linearly polarized light exhibits after passing through a sample containing chiral molecules.
- See also: polarized light
- optical section
- An effect where only a single plane (XY) with discrete axial (Z) extent contributes to an image, such as in differential interference contrast (DIC), confocal microscopy, or multiphoton microscopy. It can be leveraged to perform volumetric imaging, where a sample is imaged plane by plane (Z Stack).
- See also: Z stack, confocal microscopy, multiphoton microscopy, differential interference contrast
- optical sectioning
- A general term for imaging techniques that use an optical approach towards restricting imaging to a more well-defined plane in samples with non-negligible three-dimensional structure. Examples of optical sectioning techniques include confocal microscopy and light sheet fluorescence microscopy.
- See also: Z stack, confocal microscopy, multiphoton microscopy, light sheet fluorescence microscopy
- optical train
- The complete set of optical and mechanical components that comprise the optical system (microscope). The central axis that traverses the system is known as the optical axis.
- See also: optical axis, microscope
- optical transfer function (OTF)
- A complex-valued function describing the contrast with which different spatial frequencies are transmitted by an optical system, accounting for phase effects. It is the autocorrelation of the pupil function. It also forms a Fourier transform pair with the intensity point-spread function.
- See also: modulation transfer function, contrast transfer function, phase transfer function, pupil function, Fourier transform, intensity point-spread function
- optical trap
- see optical tweezers
- optical tube length
- The distance between the objective lens back focal plane and the primary image formed at the eyepiece field stop. Note that this definition is different from that of mechanical tube length.
- See also: mechanical tube length
- optical tweezers
- A technique in which a particle ranging in size from single molecules to small single cells can be held stable in space via interaction with a focused beam of light
- Synonyms: optical trap, laser tweezers, single-beam gradient force trap
- optogenetics
- A technique in which light is used to control various cellular activities via genetically-encoded light-sensitive proteins.
- ordinary ray
- A birefringent material will split light incident at a non-zero angle to its optic axis into two rays with orthogonal linear polarization states. The refractive index experienced by one of the rays will be constant and it undergoes refraction as expected, obeying Snell's law.
- See also: birefringence, extraordinary ray, polarization, polarized light microscopy, Snell's law
- organ-chip
- see organ-on-chip
- organ-on-a-chip
- see organ-on-chip
- organ-on-chip (OOC)
- A device designed to mimic a particular physiological environment using cultured cells. It typically has complex 3D structure and frequently includes multiple cell types to better recapitulate organ function.
- Synonyms: organ-chip, organ-on-a-chip
- See also: organoid
- organoid
- Synthetic, multicellular 3D-cultured structures that mimic key functions of a particular organ.
- See also: organ-on-chip
- overcorrection
- In an optical system, overcorrection refers to the improper use of correction optics (e.g. a correction collar), resulting in unoptimized correction for spherical aberration.
- See also: correction collar, spherical aberration
- oversampling
- The digitization of a signal at a higher frequency than necessary to fully resolve it. According to the Nyquist sampling theorem the absolute minimum sampling rate is 2X. 2.3X is commonly recommended and 3 - 5X can be useful when the data is to be deconvolved. Sampling in excess of a recommended range is oversampling.
- See also: sampling, sampling rate, Nyquist sampling
