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349 terms

Photonics Dictionary: O

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optical axis
optical add-drop module
Office of Aeronautics, Exploration and Technology
optical address light modulator
optical-analog matrix processing
off-axis rejection; open area ratio
The 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 beam
In 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 distance
The distance between the object and the cornea, or the first surface of the objective in an optical device.
object displacement
The movement of an object seen through a refracting prism toward the apex of a prism.
object distance
The distance between the object and the cornea, or the first surface of the objective in an optical device.
object space
In an optical system, the space between the object being viewed and the system entrance pupil.
object working distance
Distance between the front vertex of a lens and the object.
The 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 aperture
The 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 grating
A 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 prism
1. 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 crystal
A 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 error
The image error that results from astigmatism, coma, oblique spherical aberration, lateral color and distortion.
oblique illumination
A 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...
observatory dome
A 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°.
An acid-resistant, lustrous volcanic glass, usually black or banded.
optical computing
A device that completely or partially restricts the amount of light reaching the eye.
optical Chinese character recognition
optical coherence domain reflectometer
optics coupling display unit
ocean color
Refers 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...
optical countermeasure
optically coupled oscillator
optical character recognition; optical character reader
optical coherence tomography
In 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 -> eyepiece
Also 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 accommodation
Ocular accommodation is the process by which the eye changes its optical power to maintain a clear image (focus) on an object as its distance varies. This process is essential for seeing objects at...
ocular accommodation reflex
The 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 prism
The prism used in a rangefinder to bend the lines of sight through the instruments into the eyepieces.
ocular surface
That surface of a lens located nearest to the eye.
An 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...
optical character verification
optical continuous wave reflectometer
optical density; outside diameter
optical disc memory
optical distribution network
optical data processing
optical data storage
optoelectronic integrated circuit
original equipment manufacturer
optical emission spectroscopy

Photonics DictionaryO

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