[A.A] (This informative annex is not part of ANSI/IES RP‑16‑17; it is included to provide definitions from other sources that the user may encounter.)
alphanumerical display (digital display) An electrically-operated display of letters and/or digits. Tungsten filaments, gas discharges, light emitting diodes, liquid crystals, projected numerals, illuminated numbers, fluorescent screens, and other principles of operation may be used.
bolometer Thermal receptor in which the heating of the part that absorbs the radiation gives rise to a change in its electrical resistance.*
light controlled silicon controlled rectifier, SCR (also called photothyristor) Photoelectric receptor utilizing a four-layer p‑n-p‑n junction rectifier whose “on,” or conducting state, is controlled by absorbed radiation.
liquid crystal display, LCD A display made of material whose reflectance or transmittance changes when an electric field is applied.
numerical display (digital display) An electrically operated display of digits. Tungsten filaments, gas discharges, light-emitting diodes, liquid crystals, projected numerals, illuminated numbers, and other principles of operation can be used.
photoconductive cell Photoelectric receptor utilizing a semiconductor in which absorption of radiation gives rise to an increase in conductivity by the internal photoelectric effect.*
photodiode Photoelectric receptor in which absorption of radiation in the neighborhood of a p‑n junction between two semiconductors, or of a contact between a semiconductor and a metal, produces a change of resistance depending on the current direction.*
photoelectric receiver A device that reacts electrically in a measurable manner in response to incident radiant energy.
phototransistor Photoelectric receptor utilizing semiconductors in which the photoelectric effect is produced in the neighborhood of a double p‑n junction (p‑n‑p or n‑p‑n) possessing amplification properties.*
Note: A phototransistor may be combined with other transistors in a single case or on a “chip” in order to increase the overall amplification.
phototriac Photoelectric receptor utilizing a symmetrical silicon controlled rectifier (SCR) or double‑ended thyristor of five-layer semiconductor construction for AC application whose “on,” or conducting, state is controlled by absorbed radiation.
phototube (photoemissive cell) Photoelectric receptor comprising a vacuum or gas‑filled electronic tube containing a cathode capable of emitting electrons by the external photoelectric effect.
photovoltaic cell Photoelectric receptor in which absorption of radiation in the neighborhood of a p‑n junction between two semiconductors, or of a contact between a semiconductor and a metal, produces an electromotive force.*
pyroelectric detector – A radiation detector in which the sensitive element is a thin layer of a pyroelectric material. Such a material changes polarization when heated, and thus develops a charge across its thickness, which causes a current to flow between electrodes on the two surfaces.
quantum efficiency (of a detector) (η) Ratio of the number of elementary events (such as release of an electron) contributing to the detector output, to the number of incident photons.*
(radiation) thermocouple Thermal receptor in which the absorbed radiation produces, by the heating of a contact between two conductors of different kind, an electromotive force by the thermoelectric or Seebeck effect.*
(radiation) thermopile Thermal receptor comprising a number of thermocouples.*
* International Lighting Vocabulary, CIE S 017/E:2011. Vienna, Austria: International Commission on Illumination; 2011.« Back to Definitions Index