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Quartz Glass for Ultra HighPressure and High IntensityDischarge Lamps

Heraeus Quarzglas

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Projection – imaging your life

New projection technologies, e.g. back-illumination, are driving the various digitalillumination solutions. At the same time,they continuously increase the reliabilityand quality of the signal produced. Thetrends in this modern technology, e.g.projectors, TV and electronic cinema,support large-area pictures, higherbrightness, wider viewing angles and amore compact size. All these featuresshould be available at favourable costs.

One key element of the new digitalprojection applications is a high-intensitydischarge lamp. A point-like arc combinedwith lifetimes of usually several thousandhours, especially in rear projection TVs,is required to meet consumers’ needs.The light source, normally a mercuryshort-arc lamp with a quartz envelope,

operates with power loads up to 300W/cm, leading to surface temperaturesover 1000°C and fill gas pressures over 200 bars.

Modern projection systems need to becompact in size and should producehigh-resolution images of high bright-ness. The trend is hence more compactlamps with higher power and higherlight output. As a result, the wall loadcontinually increases. At the same time,a longer lamp lifetime and a constantlight output is required in new applica-tions, especially in rear projection TVs.

Advanced Material for Highest Demands

Improved lightingperformance and

efficiency, a compactsize and long lifetimeshould be available at

favourable costs

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reduced discoloration after annealing

minimum hydroxyl (OH-) and hydrogen content

In addition HLQ-170 supports the highlyautomatic production of lamps by provid-ing tightest geometric tolerances.

In view of such high requirements, theeconomical and technical advantages ofobtaining quartz lamp tubes from a well-experienced producer such as HeraeusQuarzglas are obvious.

Heraeus has supplied high-quality quartzglass for over one hundred years. For thedemands of modern projection technology,Heraeus offers an advanced quartz glassthat meets the high requirements of ultra-high-pressure (UHP) lamps. The newHLQ-170 is an improved quartz materialbased on proven HLQ grades. It combinestypical HLQ features, e.g. the excellentheat resistance and workability, with newproperties:

higher purity, espcecially a low alkaline and iron content

higher re-crystallisation resistance

a low bubble and defect content

Customized quartz solutions from Heraeus for UHP-application

Reduced electrode distance in new lamptypes result in higher wall loads and higerwall temperatures.

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UHP Lamps Need High Performance Quartz Glass

Using own purifica-tion technologies,

Heraeus producesquartz glass of

purities up to 99.999 %

Short-arc lamps are an integral part ofmodern projection systems. Permanentdevelopment is needed to ensure aperformance that meets the high require-ments. To suit the decreasing lamp sizeand increasing power, high-performancematerials and lamp components must beemployed. In addition to electrodes andfilling gas, the quartz glass bulb is one keyelement with a very strong impact on lampperformance. Quartz glass in UHP lampsneeds to withstand the extreme operatingconditions, i.e. temperatures higher than1000°C, pressures more than 200 barsand a power more than 200 W!

High purity – crucial for a long lamplifetime

Due to the high operating temperatureand wall load, standard fused quartzglass approaches its limits. Typical

problems that limit the lifetime of yourlamp applications are:

explosion due to mechanical instab-ility of wall related to thermal loadsreaching the limits of quartz bulbs

ignition and operation problems causedby outgasing hydroxyl and hydrogenfrom the quartz glass bulb

increasing absorption and heat dis-sipation caused by discoloration ofquartz glass

wall blackening caused by alkalines,especially sodium, lowering thetungsten solubility

re-crystallization starting at alkalineseeds in quartz bulb during coolingdue to phase transformation

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HLQ-170: High-PerformanceLow-Alkaline Quartz Glass Made by Heraeus

HLQ-170 is the customized quartz solutionfor ultra high pressure and high-intensitydischarge lamps from the well-experiencedproducer Heraeus Quarzglas.

For highest demands, Heraeus offersHLQ-270, a high-performance quartzmaterial with a further reduced totalalkaline content < 250 ppb. Moreover,HLQ-270 is drawn without die or mandrel,featuring maximum homogeneity andblemish-free surfaces without any conta-mination. Please contact us for moreinformation!

As a result of charge transfers caused byimpurities or trace elements like iron, quartzglass may exhibit discoloration. High purity ofHLQ-170 and HLQ-270 solves this problem.

Heraeus developed HLQ-170, a new clearfused quartz tubing, especially designedfor high-temperature and high-pressurelamps, e.g. UHP lamps in digital projec-tion and rear projection TVs and high-performance lamps for the automotiveindustry.

The technical advantages of HLQ-170in these applications are based on itssuperior properties:

tight tolerances of wall thickness anddiameter

extremely low bubble and defectcontent

lowest hydroxyl and hydrogencontent

high transmittance and reduceddiscoloration after annealing

highest purity, especially a low alkaline content

high heat resistance and high re-crystallization resistance

Typical Geometric TolerancesHistogramm of inner and outer diameter distribution

1,92 1,96 2,00 2,04 5,96 6,00 6,04 ID (mm) OD (mm)

1.500

1.350

1.200

1.050

900

750

600

450

300

150

0

Typical Optical Transmission of HLQ-170from UV to IR Spectral Range

100

90

80

70

60

50

40

30

20

10

0

Tran

smis

sion

(%

)

200 300 400 500 600 700 800Wavelength (nm)

thickness: 2mm

Typical Impurity Content inppb (ng/g) of HLQ-170

Li Na K Mg Ca Fe Cu Cr Mn Al

100 200 250 50 300 80 < 10 < 10 < 10 8000

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Heraeus Production Process – Three Steps to Advanced Performance Materials

For over one hundred years Heraeushas accelerated innovations in optics,semiconductors and lamps by providinghighest-quality quartz glass tailored tothe different applications.

As the largest integrated quartz glassmanufacturer, Heraeus offers differentfusion methods and inhouse purificationof raw materials. Manufacture of elec-trically fused HLQ-170 includes:

Inhouse Purification

HLQ-170 is based on purest pegmatiticquartz grain sources. In addition, specialinhouse treatment guarantees moreefficient reduction of alkaline and traceelement contents before quartz glassfusion.

The typical contents of alkaline, calciumand iron are tabulated on page 5. Theresult are less seeds for defect or re-crystallization centres and a longerlifetime of our quartz tubes.

Electrical Fusion

The high purity grain is fused in a verypure tungsten crucible under reducingatmosphere by electrical heating. Elec-trically fused quartz glass has a highviscosity and a high heat resistance. Thequartz glass tubes are pulled with aspecial tool from the melt. This ensurestightest geometric tolerances and highestvisual quality.

HLQ-170 quartz tubing is available in awide range of diameters and wall thick-nesses. Developed especially for high-temperature and high-pressure applica-tion, we support tightest geometric tole-rances for small tube geometries, e.g. 4x 1 mm, 6 x 2 mm and 7. 4 x 2 mm.

Annealing

A low hydroxyl and hydrogen content isone of the most important features ofquartz glass in high-intensity dischargelamps.

Using a special thermal treatment,HLQ-170 is offered with a hydroxyl(OH-) content of less than 0.3 ppm.

Properties of Electrically-Fused Quartz Glass

Heraeus is using own purification technologyto produce highest quality grain for electricalfusion of HLQ-170 quartz glass tubes.

Density 2.203 g/cm3

Modulus of elasticity (at 20 °C) 7.25 x 104 N/mm2

Poisson’s ratio 0.17

Compressive strength 1.150 N/mm2

Tensile strength 50 N/mm2

Bending strength 67 N/mm2

Torsional strength 30 N/mm2

Softening temperature 1.710°C

Annealing temperature 1.220°C

Strain temperature 1.125°C

Max. working temperaturecontinousshort-term

1.160°C1.300°C

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Heraeus – Quartz Glass Tailored to Lamp Applications

Heraeus Quarzglas offers a wide spectrumof high-quality quartz glass tubes for lampand lighting applications. Heraeus is theonly quartz glass manufacturer able tofuse three different quartz glass types withdifferent specific properties: electrically-fused quartz glass (HLQ-grades), flame-

fused quartz glass (Heralux and M-Grades)and synthetic fused silica (Suprasil). Theselection shows our full range of quartzglass grades. All grades are available inannealed version. During annealing freehydrogen and unstable hydroxyl (OH) groupsare removed. HLQ-grades are available

with an OH content < 1 ppm. Flame-fusedquartz glass and Suprasil 310 contain stableOH-groups which improve the resistance toUV damage and solarisation. Suprasil 300is dried by the use of chlorine which resultsin an OH content < 1 ppm. Please contactus for more information.

HLQ

170

HLQ

200

HLQ

210

HLQ

270

HLQ

235

HLQ

250

HLQ

382

M 2

35 p

lus

M 3

82 p

lus

Her

alux

plu

s

Her

alux

vuv

Sup

rasi

l 310

Sup

rasi

l 300

highest UV and VUV transmission

highest resistance to VUV irradiation

ozone free

uv blocking

highest devitrification resistance

highest temperature resistance

high and highest homogeneity

nearly perfect surface

highest chemical purity

economic grade

Applications

172 nm excimer lamps

low pressure lamps with 185 nm emission

high transmittance long-life sleeves for 185 nm and 254 nm applications

low pressure lamps

sleeves for 254 nm disinfection

medium pressure lamps

metal halide lamps

highest pressure lamps and HID lamps, e.g. for projection or automotive

short arc lamps, e.g. for i-line steppers, cinema and stage

long arc lamps, e.g. for laser exitation

infrared lamps

Properties