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Quartz Tungsten Halogen Lamps

Quartz Tungsten Halogen Lamps
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132 Phone: 1-800-222-6440 • Fax: 1-949-253-1680 L i g h t S o u r c e s TECHNICAL REFERENCE MONOCHROMATOR AND INCANDESCENT SOURCES ARC SOURCES DEUTERIUM SOURCES CALIBRATION SOURCES FIBER ILLUMINATORS PHOTOLITHOGRAPHY SOLAR SIMULATORS INSTRUMENTS ACCESSORIES FOR ORIEL LIGHT SOURCES Oriel Quartz Tungsten Halogen Lamps Various quartz tungsten halogen Lamps. Quartz Tungsten Halogen (QTH) lamps are popular visible and near infrared sources because of their smooth spectral curve and stable output. They do not have the sharp spectral peaks that arc lamps exhibit, and they emit little UV radiation, see the spectral irradiance curves of our QTH lamps. Our QTH lamps use a doped tungsten filament inside a quartz envelope. They are filled with rare gas and a small amount of halogen. Current flowing through the filament heats the tungsten to >3000 K. The filaments of our 10 to 250 W lamps are dense planar structures for highest image brightness. The white light produced radiates through the clear quartz envelope. Color Temperature Color temperature and total radiated lumens are useful for comparison of lamp performance in the visible. The efficiency in the visible, the number of lumens per watt, increases with color temperature because the spectral distribution curve moves to shorter wavelengths, i.e. towards the visible, with increasing temperature (Fig. 1). The emissivity of tungsten is ~0.4, in the visible, so the output is less than that of a full radiator of equivalent temperature. Because the emissivity varies with wavelength, there is not an exact match of spectral distribution with a full radiator (see Fig. 2). The color temperature listed for our lamps, in the Ordering Information Table, is the “correlated color temperature”. This is the temperature in K (Kelvin) of a full radiator (black body), which emits light of similar color balance (chromaticity) as the tungsten halogen lamp. It is a recognized mathematical best match. For a filament temperature of 3300 K, the color temperature is approximately 3390 K. 0.90 0.95 1.0 1.05 0.8 0.85 0.9 0.95 1.0 1.05 1.10 1.15 OPERATING VOLTAGE/RATED VOLTAGE C. COLOR TEMP/RATED COLOR TEMP Fig. 1 Correlated color temperature and voltage relationship. 0 1000 2000 3000 4000 0.25 0.5 1.0 2.0 3.0 WAVELENGTH (ìm) SPECTRAL EXITANCE (Wm nm ) -2 -1 2 and 3 1 2 3 Fig. 2 Spectral exitance of (1) full radiator, (2) a tungsten surface and (3) a gray body with emissivity of 0.425, at all 3100 K. Lamp Life and Operating Voltage The filament parameters are chosen for a specific operating voltage. Lamp life is the average life of a number of lamps run in open air at the “rated voltage.” Operating these lamps at a higher voltage greatly reduces the life. A 6% increase in voltage reduces the operating life by 50% (Fig. 4). A small reduction in voltage gives a longer lamp life; a reduction of more than 10% may drastically shorten lamp life as the halogen cycle cannot operate effectively under this condition. • High VIS-NIR output with little UV • Smooth spectrum, stable output • High Color temperatures, >3000 K

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133 Email: sales@newport.com • Web: newport.com L i g h t S o u r c e s TECHNICAL REFERENCE CALIBRATION SOURCES DEUTERIUM SOURCES ARC SOURCES INCANDESCENT SOURCES MONOCHROMATOR AND FIBER ILLUMINATORS SOLAR SIMULATORS PHOTOLITHOGRAPHY INSTRUMENTS ACCESSORIES FOR ORIEL LIGHT SOURCES 100 90 80 0 50 100 150 200 RUNNING TIME (% OF RATED) RELATIVE LUMINOUS OUTPUT (%) CONVENTIONAL INCANDESCENT LAMP 6333 at 100 W INPUT Fig. 3 Typical Light Output vs. Time, of the 6333 QTH lamp and a conventional filament lamp. 20 10 5 1.0 0.5 0.1 OPERATING VOLTAGE/RATED VOLTAGE AVERAGE LIFE/AVERAGE LIFE AT RATED...

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Quartz Tungsten Halogen Lamps 3Pages

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Quartz Tungsten Halogen Lamps
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