lampa cu xenon

A xenon arc lamp is a specialized type of gas discharge lamp, an electric light that produces light by

passing electricity through ionized xenon gas at high pressure. It produces a bright white light that

closely mimics natural sunlight. Xenon arc lamps are used in movie projectors in theaters, in

searchlights, and for specialized uses in industry and research to simulate sunlight. Xenon headlamps in

automobiles actually use metal-halide lamps where xenon arc is only used during start-up.

Types

Xenon arc lamps can be roughly divided into three categories:

• Continuous-output xenon short-arc lamps

• Continuous-output xenon long-arc lamps

• Xenon flash lamps (which are usually considered separately)

Each consists of a glass or fused quartz arc tube with tungsten metal electrodes at each end. The

glass tube is first evacuated and then re-filled with xenon gas. For xenon flashtubes, a third

"trigger" electrode usually surrounds the exterior of the arc tube. The lamp has a lifetime of

around 2000 hours.

History and modern usage

An Osram 100 W xenon/mercury short

Xenon short-arc lamps were invented in the 1940s in Germany and introduced in 1951 by

Osram. First launched in the 21kW

projection, where they replaced the older, more complicated

continuous light generated by the xenon arc is spectrally similar to daylight, but the lamp has a

rather low efficiency in terms of

almost all movie projectors in theaters empl

watts up to 12 kW. Omnimax (Imax Dome) projection systems use single xenon lamps with

ratings as high as 15 kW.

Lamp construction

An end-view of a 151kW IMAX lamp showing the liquid

All modern xenon short-arc lamps use a fused quartz envelope with

electrodes. Fused quartz is the only economically feasible material currently available that can

withstand the high pressure (25 atmospheres for an

an operating lamp, while still being o

enhances their electron emission

coefficients of thermal expansion

molybdenum metal or Invar alloy, which are then melted into the quartz to form the envelope

seal.

Because of the very high power level

IMAX projectors, the electrode bodies are made from solid Invar and tipped with thoriated

tungsten. An O-ring seals off the tube, so th

low power applications the electrodes are too cold for efficient electron emission and are not

cooled; in high power applications an additional water cooling circuit for each electrode is

necessary. To save costs, the water circuits are often not separated and the water needs to be

deionized to make it electrically non

media dissolve into the water.

100 W xenon/mercury short-arc lamp in reflector

arc lamps were invented in the 1940s in Germany and introduced in 1951 by

kW size (XBO2001), these lamps saw wide use in

, where they replaced the older, more complicated carbon arc lamps. The white,


in terms of lumens of visible light output per watt of input power. Today,

almost all movie projectors in theaters employ these lamps, with power ratings ranging from 900

(Imax Dome) projection systems use single xenon lamps with

1kW IMAX lamp showing the liquid-cooling ports

arc lamps use a fused quartz envelope with thoriated tungsten

only economically feasible material currently available that can

withstand the high pressure (25 atmospheres for an IMAX bulb) and high temperature present in

an operating lamp, while still being optically clear. The thorium dopant in the electrodes greatly

characteristics. Because tungsten and quartz have different

coefficients of thermal expansion, the tungsten electrodes are welded to strips of pure

alloy, which are then melted into the quartz to form the envelope

Because of the very high power levels involved, large lamps are water-cooled. In those used in


seals off the tube, so that the naked electrodes do not contact the water. In



ave costs, the water circuits are often not separated and the water needs to be

to make it electrically non-conductive, which, in turn, lets the quartz or some laser

arc lamps were invented in the 1940s in Germany and introduced in 1951 by

001), these lamps saw wide use in movie

. The white,


of input power. Today,

oy these lamps, with power ratings ranging from 900

(Imax Dome) projection systems use single xenon lamps with

thoriated tungsten

only economically feasible material currently available that can

bulb) and high temperature present in

dopant in the electrodes greatly

s. Because tungsten and quartz have different

, the tungsten electrodes are welded to strips of pure

alloy, which are then melted into the quartz to form the envelope

cooled. In those used in


at the naked electrodes do not contact the water. In



ave costs, the water circuits are often not separated and the water needs to be

conductive, which, in turn, lets the quartz or some laser

Perspective view of 31kW lamp showing plastic safety shield used during shipping.

In order to achieve maximum efficiency, the xenon gas inside short

extremely high pressure — up to 30 atmospheres (440 psi / 3040 kPa)

concerns. If a lamp is dropped, or ruptures while in service, pieces o

thrown at high speed. To mitigate this, large xenon short

protective shields, which will contain the envelope fragments should breakage occur. Normally,

the shield is removed once the lamp is ins

end of its useful life, the protective shield is put back on the lamp, and the spent lamp is then

removed from the equipment and discarded. As lamps age, the risk of failure increases, so bulbs

being replaced are at the greatest risk of explosion. Because of the safety concerns, lamp

manufacturers recommend the use of eye protection when handling xenon short

Because of the danger, some lamps, especially those used in IMAX projectors, require t

full-body protective clothing.

Light generation mechanism

Xenon short-arc lamps come in two distinct varieties: pure xenon, which contain only xenon gas;

and xenon-mercury, which contain xenon gas and a small amount of

In a pure xenon lamp, the majority of the light is generated within a tiny, pinpoint

plasma situated where the electron stream leaves the fa

volume is cone-shaped, and the luminous intensity falls off exponentially moving from cathode

to anode. Electrons passing through the plasma cloud strike the anode, causing it to heat. As a

result, the anode in a xenon short

water-cooled, to dissipate the heat. The output of a pure xenon short

over the entire colour spectrum,[citation needed

very strong emission lines in the near infrared, roughly in the region from 850

spectral region can contain about 10% of the total emitted light.

In xenon-mercury short-arc lamps, the majority of the light is generated in a pinpoint

of plasma situated at the tip of each electrode. The light generation volume is s

intersecting cones, and the luminous intensity falls off exponentially moving towards the centre

of the lamp. Xenon-mercury short

UV output. These lamps are used primarily for UV

generating ozone.

1kW lamp showing plastic safety shield used during shipping.

In order to achieve maximum efficiency, the xenon gas inside short-arc lamps is maintained at an

up to 30 atmospheres (440 psi / 3040 kPa) — which poses safety

concerns. If a lamp is dropped, or ruptures while in service, pieces of the lamp envelope can be

thrown at high speed. To mitigate this, large xenon short-arc lamps are normally shipped in


the shield is removed once the lamp is installed in the lamp housing. When the lamp reaches the



placed are at the greatest risk of explosion. Because of the safety concerns, lamp

manufacturers recommend the use of eye protection when handling xenon short-

Because of the danger, some lamps, especially those used in IMAX projectors, require t

Light generation mechanism

arc lamps come in two distinct varieties: pure xenon, which contain only xenon gas;

mercury, which contain xenon gas and a small amount of mercury metal.

In a pure xenon lamp, the majority of the light is generated within a tiny, pinpoint

plasma situated where the electron stream leaves the face of the cathode. The light generation

shaped, and the luminous intensity falls off exponentially moving from cathode


in a xenon short-arc lamp either has to be much larger than the cathode or be

cooled, to dissipate the heat. The output of a pure xenon short-arc lamp is relatively flat citation needed]

though even in a high pressure lamp there are some

very strong emission lines in the near infrared, roughly in the region from 850–900

spectral region can contain about 10% of the total emitted light.

arc lamps, the majority of the light is generated in a pinpoint

of plasma situated at the tip of each electrode. The light generation volume is shaped like two


mercury short-arc lamps have a bluish-white spectrum and extremely high

output. These lamps are used primarily for UV curing applications, sterilizing

1kW lamp showing plastic safety shield used during shipping.

arc lamps is maintained at an

which poses safety

f the lamp envelope can be

arc lamps are normally shipped in


talled in the lamp housing. When the lamp reaches the



placed are at the greatest risk of explosion. Because of the safety concerns, lamp

-arc lamps.

Because of the danger, some lamps, especially those used in IMAX projectors, require the use of

arc lamps come in two distinct varieties: pure xenon, which contain only xenon gas;

metal.

In a pure xenon lamp, the majority of the light is generated within a tiny, pinpoint-sized cloud of

ce of the cathode. The light generation

shaped, and the luminous intensity falls off exponentially moving from cathode


arc lamp either has to be much larger than the cathode or be

arc lamp is relatively flat

though even in a high pressure lamp there are some

900 nm. This

arc lamps, the majority of the light is generated in a pinpoint-sized cloud

haped like two


white spectrum and extremely high

sterilizing objects, and

The very small size of the arc makes it possible to focus the light from the lamp with moderate

precision. For this reason, xenon arc lamps of smaller sizes, down to 10 watts, are used in optics

and in precision illumination for

they are being displaced by single mode laser diodes

which can produce a truly diffraction limited spot. Larger lamps are employed in searchlights

where narrow beams of light are generated, or in film production light

simulation is required.

All xenon short-arc lamps generate substantial

lines in the UV bands, and these readily pass through the fused quartz lamp envelope. Unlike the

borosilicate glass used in standard lamps, fused quartz does not

is specially doped. The UV radiation released by a short

of ozone generation. The UV radiation strikes

causing them to ionize. Some of the ionized molecules then recom

that uses short-arc lamps as the light source must contain UV radiation and prevent ozone build

up.

Many lamps have a low-UV blocking coating on the envelope and are sold as "Ozone Free"

lamps. Some lamps have envelopes made ou

"Suprasil"), which roughly doubles the cost, but which allows them to emit useful light into the

vacuum UV region. These lamps are normally operated in a pure nitrogen atmosphere.

Ceramic xenon lamps

A Cermax 2 kW xenon lamp from a video projector. A pair of heatsinks are

metal bands around the perimeter, which also double to supply power to the lamp

Xenon short-arc lamps also are manufactured with a ceramic body and an integral reflector. They

are available in many output power ratings with either UV tr

The reflector options are parabolic (for collimated light) or elliptical (for focused light). They are

used in a wide variety of applications, such as video projectors, fiber optic illuminators,

endoscope and headlamp lighting, dental lighting, and search lights.

Power supply requirements


on, xenon arc lamps of smaller sizes, down to 10 watts, are used in optics

and in precision illumination for microscopes and other instruments, although in modern times

single mode laser diodes and white light supercontinuum lasers


where narrow beams of light are generated, or in film production lighting where daylight

arc lamps generate substantial ultraviolet radiation. Xenon has strong spectral

d these readily pass through the fused quartz lamp envelope. Unlike the

used in standard lamps, fused quartz does not attenuate UV radiation unless it

. The UV radiation released by a short-arc lamp can cause a secondary problem

generation. The UV radiation strikes oxygen molecules in the air surrounding the lamp,

causing them to ionize. Some of the ionized molecules then recombine as O3, ozone. Equipment

arc lamps as the light source must contain UV radiation and prevent ozone build

UV blocking coating on the envelope and are sold as "Ozone Free"

lamps. Some lamps have envelopes made out of ultra-pure synthetic fused silica


. These lamps are normally operated in a pure nitrogen atmosphere.

Ceramic xenon lamps

A Cermax 2 kW xenon lamp from a video projector. A pair of heatsinks are clamped on the two


arc lamps also are manufactured with a ceramic body and an integral reflector. They

are available in many output power ratings with either UV transmitting or blocking windows.



ng, dental lighting, and search lights.

Power supply requirements


on, xenon arc lamps of smaller sizes, down to 10 watts, are used in optics

and other instruments, although in modern times

white light supercontinuum lasers


ing where daylight

. Xenon has strong spectral

d these readily pass through the fused quartz lamp envelope. Unlike the

UV radiation unless it

arc lamp can cause a secondary problem

molecules in the air surrounding the lamp,

, ozone. Equipment

arc lamps as the light source must contain UV radiation and prevent ozone build-

UV blocking coating on the envelope and are sold as "Ozone Free"

(such as


. These lamps are normally operated in a pure nitrogen atmosphere.

clamped on the two


arc lamps also are manufactured with a ceramic body and an integral reflector. They

ansmitting or blocking windows.



A 1 kW xenon short-arc lamp power supply with the cover removed.

Xenon short-arc lamps are low-voltage, high

coefficient. They require a high voltage pulse in the 20

require an extremely well regulated DC power source. They are also inherently unstable, prone

to phenomena such as plasma oscillation

xenon short-arc lamps require a sophisticated power supply to achieve stable, long

The usual approach is to regulate the current flowing in the lamp rather than the applied voltage.

As an example, a 4501W lamp operates normally at 181V and 251A.

Automotive headlamps

In 1991 "xenon headlamps" were introduced for vehicles. These are actually

the xenon gas is used only to provide some light immediately upon lamp startup, as required for

safety in an automotive headlamp application. Full intensity is reached 20 to 30 seconds later

once the salts of sodium and scandium

envelope is small and the arc spans only

escape of ultraviolet radiation that would tend to damage plastic headlamp components. The first

xenon headlamp burners contained m

Xenon long-arc-lamps

These are structurally similar to short

glass tube is greatly elongated. When mounted within an

frequently used to simulate sunlight. Typical uses include

age testing of materials, rapid thermal processing, and material inspection.

XBO lamps

XBO lamps are short arc lamps in which the discharge arc fires in a pure xenon atmosphere

under high pressure. XBO lamps have a

luminance. For this reason they are often used in light guide systems,

dental technology.

arc lamp power supply with the cover removed.

voltage, high-current, DC devices with a negative temperature

. They require a high voltage pulse in the 20–501kV range to start the lamp, and


plasma oscillation and thermal runaway. Because of these characteristics,

arc lamps require a sophisticated power supply to achieve stable, long

he usual approach is to regulate the current flowing in the lamp rather than the applied voltage.

1W lamp operates normally at 181V and 251A.

Automotive headlamps

" were introduced for vehicles. These are actually metal



scandium are vapourised by the heat of the xenon arc. The lamp

envelope is small and the arc spans only a few millimetres. An outer hard glass tube blocks the


xenon headlamp burners contained mercury; newer types do not.

lamps

These are structurally similar to short-arc lamps except that the arc-containing portion of the

glass tube is greatly elongated. When mounted within an elliptical reflector, these lamps are

frequently used to simulate sunlight. Typical uses include solar cell testing, solar simulation

age testing of materials, rapid thermal processing, and material inspection.


under high pressure. XBO lamps have a very good color rendering and extremely high

luminance. For this reason they are often used in light guide systems, e.g., for endoscopy or

negative temperature

range to start the lamp, and


. Because of these characteristics,

arc lamps require a sophisticated power supply to achieve stable, long-life operation.

he usual approach is to regulate the current flowing in the lamp rather than the applied voltage.

metal-halide lamps;



are vapourised by the heat of the xenon arc. The lamp

. An outer hard glass tube blocks the


containing portion of the

reflector, these lamps are

solar simulation for


very good color rendering and extremely high

, for endoscopy or

lampa cu xenon

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