The FEL
lamp (less accurately called a
light bulb
Electric light is an artificial light source powered by electricity.
Electric Light may also refer to:
* Light fixture, a decorative enclosure for an electric light source
* ''Electric Light'' (album), a 2018 album by James Bay
* Electric Light ( ...
) is an
ANSI
The American National Standards Institute (ANSI ) is a private nonprofit organization that oversees the development of voluntary consensus standards for products, services, processes, systems, and personnel in the United States. The organiz ...
standard 1000 watt quartz
halogen lamp
A halogen lamp (also called tungsten halogen, quartz-halogen, and quartz iodine lamp) is an incandescent lamp consisting of a tungsten filament sealed in a compact transparent envelope that is filled with a mixture of an inert gas and a small ...
with a
G9.5 medium 2-pin base used in many stage and studio lights that costs around $12 and is available from a number of manufacturers including
GE,
Osram
OSRAM Licht AG is a German company that makes electric lights, headquartered in Munich and Premstätten (Austria). OSRAM positions itself as a high-tech photonics company that is increasingly focusing on sensor technology, visualization and trea ...
, Ushio, Eiko, and
Philips
Koninklijke Philips N.V. (), simply branded Philips, is a Dutch multinational health technology company that was founded in Eindhoven in 1891. Since 1997, its world headquarters have been situated in Amsterdam, though the Benelux headquarter ...
. Note that the term FEL is an
ANSI
The American National Standards Institute (ANSI ) is a private nonprofit organization that oversees the development of voluntary consensus standards for products, services, processes, systems, and personnel in the United States. The organiz ...
designation (not an acronym).
Description
FEL lamps are a
working standard used to ensure optical equipment meets
NIST
The National Institute of Standards and Technology (NIST) is an agency of the United States Department of Commerce whose mission is to promote American innovation and industrial competitiveness. NIST's activities are organized into physical s ...
standards.
Specially seasoned and calibrated FEL lamps are used in laboratories as
radiance
In radiometry, radiance is the radiant flux emitted, reflected, transmitted or received by a given surface, per unit solid angle per unit projected area. Radiance is used to characterize diffuse emission and reflection of electromagnetic radiati ...
and
irradiance
In radiometry, irradiance is the radiant flux ''received'' by a ''surface'' per unit area. The SI unit of irradiance is the watt per square metre (symbol W⋅m−2 or W/m2). The CGS unit erg per square centimetre per second (erg⋅cm−2⋅s−1) ...
standards (related to
luminance
Luminance is a photometric measure of the luminous intensity per unit area of light travelling in a given direction. It describes the amount of light that passes through, is emitted from, or is reflected from a particular area, and falls wit ...
and
illuminance
In photometry (optics), photometry, illuminance is the total luminous flux incident on a surface, per unit area. It is a measure of how much the incident light illuminates the surface, wavelength-weighted by the luminosity function to correlate ...
) used to calibrate
photometer
A photometer is an instrument that measures the strength of electromagnetic radiation in the range from ultraviolet to infrared and including the visible spectrum. Most photometers convert light into an electric current using a photoresistor, ...
s,
light meter
A light meter (or illuminometer) is a device used to measure the amount of light. In photography, an exposure meter is a light meter coupled to either a Digital data, digital or analog calculator which displays the correct shutter speed and f-nu ...
s,
spectrophotometers and other laboratory instruments.
An FEL lamp purchased from
NIST
The National Institute of Standards and Technology (NIST) is an agency of the United States Department of Commerce whose mission is to promote American innovation and industrial competitiveness. NIST's activities are organized into physical s ...
that has been calibrated for light output,
color temperature
Color temperature is a parameter describing the color of a visible light source by comparing it to the color of light emitted by an idealized opaque, non-reflective body. The temperature of the ideal emitter that matches the color most clos ...
, and
spectral energy distribution
A spectral energy distribution (SED) is a plot of energy versus frequency or wavelength of light (not to be confused with a 'spectrum' of flux density vs frequency or wavelength). It is used in many branches of astronomy to characterize astron ...
is over ten thousand dollars. NIST Traceable FEL lamps are available from commercial suppliers.
Sockets
Matching sockets for the
G9.5 base include
Sylvania TP22, TP220,
Buhl Electric QEW-2, QEW-21, QEW-22, Bender + Wirth 968, Ushio: C-3, C-3(A). The calibration lamps are generally modified to use a larger bi-post base that fits into special
kinematic mount sockets for precise optical alignment.
Although the socket for calibration lamps is not polarized, polarity must be observed because the calibration lamps are normally run on DC and the lamp
filament
The word filament, which is descended from Latin ''filum'' meaning " thread", is used in English for a variety of thread-like structures, including:
Astronomy
* Galaxy filament, the largest known cosmic structures in the universe
* Solar filament ...
will recrystallize according to the applied DC polarity.
References
{{Reflist
External links
Honeywell Floor LampOSA Handbook of Applied PhotometryCharacterization of Modified FEL Quartz-Halogen Lamps for Photometric Standards
Types of lamp