8,617 terms
Photonics Dictionary
Lawson criterionDefines the minimum operational standards for a self-sustaining fusion reactor as equivalence between energy released per volume unit and kinetic energy per unit volume.
lay lengthIn a fiber optic cable, the longitudinal length required for the transmission media, wrapped around a central member, to complete one helical wrap. Also called pitch.
layoutIn the optical shop, the process of positioning and marking a blank or lens before surfacing, cutting and edging.
lbfpound-force
LBIClaser-beam-induced current
LBOlithium triborate
LBPlaser beam printer
LCCliquid crystal cell; leadless chip carrier
LCDliquid crystal display
LCIMlow-coherence interference microscope
LCLlaser communication link
LCLVliquid crystal light valve
LCMlaser cloud mapper
LCOSliquid crystal on silicon
LCPOFlarge-core plastic optical fiber
LCSliquid crystal shutter
LCVDlaser chemical vapor deposition
LDlaser desorption
LDAlaser Doppler anemometry
LDDlaser diode driver
LDEFLong Duration Exposure Facility
LDRlight-dependent resistor; linear dynamic range
LDSlaser dazzle system
LDVlaser Doppler velocimeter
leachingThe process of removing some of the constituents of a glass surface by chemical action.
lead selenide cellA thin-film photoconductive cell that is sensitive to the infrared region. The photosensitive material of the cell is composed of lead selenide, and the cell is used in the detection of infrared...
lead sulfide cellA photoconductive cell having greatest sensitivity in the infrared region. The photosensitive material of the cell is lead sulfide, which is deposited on a glass plate.
lead zirconate titanateA ferroelectric polycrystalline ceramic material used in optical memories for computers and as a piezoelectric transducer.
leading edge spikeIn a sequence of laser pulse emissions, the intitial pulse that often helps initiate a reaction at the target surface, whereas the trailing edge maintains the reaction.
leaky modeIn an optical waveguide, a mode whose field decays monotonically for a finite distance in the transverse direction but which becomes oscillatory everywhere beyond that finite distance.
leaky rayIn an optical waveguide, a ray for which geometric optics would predict total internal reflection at the core boundary, but which suffers loss by virtue of the curved core boundary.
least circle of confusionThe circle of confusion is a defocused or aberrated image of a point. Focus is generally set where the diameter of this circle is minimized or least.
LECliquid encapsulated crystal
LEDlight-emitting diode
LED -> light-emitting diodeAn LED, or light emitting diode, is a semiconductor device that emits light when an electric current passes through it. LEDs are widely used in various applications due to their energy efficiency,...
LEEDlaser-energized explosive device; low-energy electron diffraction
legacy fiberOlder fiber optic cable that may not be suitable for state-of-the-art applications and that is difficult for suppliers to sell.
LEGSlaser electron gamma source
leman prismAn erecting prism that inverts and reverses the image. It displaces the optical axis but does not deviate it.
Lenard tubeAn electron-beam tube designed so that the beam can be carried through a portion of the wall of an evacuated enclosure.
lens barrelThe mechanical structure that holds a number of individual lens elements.
lens bench -> optical benchA support for optical parts comprising a solid bed that permits precise longitudinal movement of one component relative to the others, and a number of sliders equipped with holders for lenses, lamps,...
lens blankA lens blank is a piece of optical material in a raw, unfinished state, typically in the form of a disk or block, from which lenses are eventually fabricated. Lens blanks are made from various...
lens discA rotating disc that holds several lenses of differing focal length about a diameter. Used to switch lenses in a system while maintaining focus.
lens elementOne optical element of a multielement lens. See optical element.
lens measureA tool used to determine the curvature of a lens surface in terms of dioptric power. See lens watch; spherometer.
lens meridianA line passing through the center of a lens surface, from edge to edge.
lens moldingThe production of rough glass lens blanks that are pressed while red-hot to the approximate size and shape of the finished lens, ready for fine grinding and polishing. Large companies often do their...
lens mountThe metal tube that maintains the optical components of a lens in proper relationship. Some lenses are mounted in metal cells, which in turn are screwed to the front and rear of a shutter or lens...
lens speedAlso known as f number, lens speed is commonly represented as the ratio of the focal length to the diameter of the lens. Lower f numbers produce brighter images.
Photonics Dictionary