7,367 terms
Photonics Dictionary
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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...
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°.
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 accommodationOcular 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 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.
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
OESoptical emission spectroscopy
OFDopen-face detector
OFDRoptical frequency domain reflectometer
off-axis paraboloidal mirror -> paraboloidal mirrorA concave mirror that has the form of a paraboloid of revolution. The paraboloidal mirror may have only a portion of a paraboloidal surface through which the axis does not pass, and is known as an...
offset prismA prism or prism assembly that serves to displace the instrument's optical axis.
OFToptical fiber thermometry
ohmThe electrical resistance between two points of a conductor when a constant difference of potential of one volt, applied between these points, produces in this conductor a current of one ampere, the...
OIDAOptoelectronics Industry Development Association (USA)
OIGoptically isolated gate
oil-immersion objectiveA form of high-power microscope objective where the space between the object and the first element is filled with an oil having the same index as that element. This form reduces losses, increases the...
oil-on plateA polished plano-parallel plate that is contacted to an unpolished glass surface to permit see-through analysis of the material. The plate eliminates effects because of the surface quality of the...
OISLoptical intersatellite link
OITDAOptoelectronic Industry & Technology Development Association (Japan)
OJRLOptoelectronics Joint Research Laboratory (Japan)
OLBRoperational laser beam recorder
oleophobicOleophobic is a term used to describe substances or materials that repel or resist oils. The word oleophobic comes from the Greek words "oleo," meaning oil, and "phobos," meaning fear. Oleophobic...
OLToptical lay-up template; optical line terminator
OLTSoptical loss test set
OMoptical master
Photonics Dictionary