339 terms
Photonics Dictionary: O
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Oopacity
OAoptical axis
OADMoptical add-drop module
OAETOffice of Aeronautics, Exploration and Technology
OALMoptical address light modulator
OAMPoptical-analog matrix processing
OARoff-axis rejection; open area ratio
objectThe figure seen through or imaged by an optical system. It may contain structures, natural or artificial, or it may be the real or virtual image of an object formed by another optical system. In...
object beamIn holography, the wave of light that illuminates the object to be recorded, which diffracts it to the recording medium, where it interferes with the reference beam, generating the hologram.
object conjugate -> object distanceThe distance between the object and the cornea, or the first surface of the objective in an optical device.
object displacementThe movement of an object seen through a refracting prism toward the apex of a prism.
object distanceThe distance between the object and the cornea, or the first surface of the objective in an optical device.
object spaceIn an optical system, the space between the object being viewed and the system entrance pupil.
object working distanceDistance between the front vertex of a lens and the object.
objectiveThe optical element that receives light from the object and forms the first or primary image in telescopes and microscopes. In cameras, the image produced by the objective is the final image. In...
objective aperture -> clear apertureThe limited light-gathering area of an optical system. The area is normally restricted to an edge or outer surface of an individual component. Also known as free aperture or objective aperture. The...
objective gratingA coarse diffraction grating that is used to form a scale of intensities to determine the relative magnitudes of stars. The grating is placed over the objective of a telescope to form a diffraction...
objective prism1. A prism used in some instruments to bend light 90° before it enters the objective. 2. A dispersing prism located in front of an astronomical telescope objective to produce spectra of all...
oblate crystal -> negative crystalA 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...
oblique errorThe image error that results from astigmatism, coma, oblique spherical aberration, lateral color and distortion.
oblique illuminationA common technique in microscopy, oblique illumination is one in which the object is illuminated by a light source that is at an oblique angle (on the side) to the optical axis. This technique is...
oblique spherical aberrationcoma, fifth order aberration with on-axis focal point variation with incident off axis ray height position
observatory domeA hemispherical covering that is rotatable about a central axis. There is a slit opening along one side wide enough to allow a telescope to be directed at any vertical angle up to 90°.
obsidianAn acid-resistant, lustrous volcanic glass, usually black or banded.
OCoptical computing
occluderA device that completely or partially restricts the amount of light reaching the eye.
OCCRoptical Chinese character recognition
OCDRoptical coherence domain reflectometer
OCDUoptics coupling display unit
ocean colorRefers to the characteristic hue of the ocean according to the presence and concentration of specific minerals or substances, such as chlorophyll. Atmospheric aberrations of color must be corrected...
OCMoptical countermeasure
OCOoptically coupled oscillator
OCRoptical character recognition; optical character reader
OCToptical coherence tomography
octaveIn optics, an octave typically refers to a range of frequencies or wavelengths that spans a factor of 2. In other words, when dealing with optics, an octave encompasses a doubling of frequency or...
ocular -> eyepieceAlso known as ocular. The lens system used between the final real image in a visual optical system and eye. It acts as an image magnifier. Many types of eyepieces are known; e.g., the Huygens used in...
ocular accommodationThe physical adaption of the eye lens, by means of ciliary muscle contraction, in order to maintain a clear, in focus image of light and other objects and surroundings at a given distance onto the...
ocular accommodation reflexThe eye's involuntary reaction in the process of accommodation. This reflex is most dramatic in response to looking at a distant object after having previously been focused on a near object or vice...
ocular prismThe prism used in a rangefinder to bend the lines of sight through the instruments into the eyepieces.
ocular surfaceThat surface of a lens located nearest to the eye.
oculometerAn electro-optical infrared tracker consisting of a beamsplitter, an illuminating source, an image dissector tube and an electronics unit, that automatically acquires and tracks particular eye...
OCVoptical character verification
OCWRoptical continuous wave reflectometer
ODoptical density; outside diameter
ODMoptical disc memory
ODNoptical distribution network
ODPoptical data processing
ODSoptical data storage
OEICoptoelectronic integrated circuit
OEMoriginal equipment manufacturer
Photonics DictionaryO