Quartz Halogen Lamp Research Articles

A new FEL-type quartz-halogen lamp as an improved standard of spectral irradiance

Based on extensive investigations of almost 100 high-power quartz-halogen lamps covering thirteen different types, seven different manufacturers and different batches with a total operating time of about 27000 h, a new type of lamp (1000 W T6 modified FEL-type lamp, Osram Sylvania Inc.) has been selected and its operating conditions have been optimized. This lamp, which after seasoning is about ten times more stable than the best lamps used before, is recommended as a reference and transfer standard of spectral irradiance in the whole range between 250 nm and 3 µm. While excellent short-term and long-term stability over operating times of several hundreds of hours can be achieved, the disadvantages of the new standard lamp lie in a long seasoning time (80 h to 100 h) and a noticeable sensitivity of the seasoned lamps to shock and vibrations. Typical results of the characterization, calibration and reproducibility of the new standard lamp are presented and discussed in order to illustrate its performance and to demonstrate how to use it under optimal operation conditions.

A stabilized transfer-standard system for spectral irradiance

High-power quartz-halogen lamps have been in use as transfer standards for a long time. However, even the best lamps available are not stable enough to match the increasing requirements stemming from the progress of measuring techniques. In particular, long-term stability in the ultraviolet-B region has to be improved. In order to achieve higher stability, it is necessary to change the operating conditions from constant-current to a detector-controlled system. The new OMTec transfer-standard system, consisting of a control unit including power supply and a lamp detector unit, is described. Its main features are: long-term stability with a deviation of the spectral radiant flux from the calibration values of less than 3 × 10-5 h-1 during nearly 400 hours of operating time throughout the spectral range from the ultraviolet-B to the near-infrared; continuous check on stability by monitoring and viewing the measured detector photocurrents; reduction of the required seasoning time by a factor of three thus enhancing the lifetime of the lamp; storage of lamp and calibration data in the lamp detector unit for external use.

Ultraviolet Spectral Irradiance Scale Comparison: 210 nm to 300 nm.

Comparison of the irradiances from a number of ultraviolet spectral irradiance standards, based on different physical principles, showed agreement to within their combined standard uncertainties as assigned to them by NIST. The wavelength region of the spectral irradiance comparison was from 210 nm to 300 nm. The spectral irradiance sources were: an electron storage ring, 1000 W quartz-halogen lamps, deuterium arc lamps, and a windowless argon miniarc.

Improved uniformity of multielement thin films prepared by off-axis pulsed laser deposition using a new heater design

A new compact substrate heater for the pulsed laser deposition (PLD) technique has been developed. The heater is built up of a radiation part, consisting of two quartz halogen lamps, and a rotating absorber, made of a SiC disk, to which the substrate is attached. The advantage of this system in comparison to conventional heaters is its suitability for substrate temperatures up to 800 °C in any ambient (vacuum as well as corrosive gases). The heater is applied for the deposition of thin, multielement films with improved thickness uniformity using off-axis PLD. This technique makes use of a rotating substrate which is off-centered from the depositing plasma plume. The thickness profile is modeled using predetermined stationary thickness distributions. For a variety of multielement materials good experimental uniformities in terms of thickness (in close agreement with the calculations) and of chemical composition are obtained. A relation is found between the value of experimental parameters and the achievable uniformity area within a large pressure range.

Irradiance of Horizontal Quartz-Halogen Standard Lamps.

Spectral irradiance calibrations often require that irradiance standard lamps be oriented differently than the normal calibration orientation used at the National Institute of Standards and Technology and at other standards laboratories. For example, in solar measurements the instruments are generally upward viewing, requiring horizontal working standards for minimization of irradiance calibration uncertainties. To develop a working standard for use in a solar ultraviolet intercomparison, NIST determined the irradiance of quartz-halogen lamps operating in the horizontal position, rather than in the customary vertical position. An experimental technique was developed which relied upon equivalent lamps with independent mounts for each orientation and a spectroradiometer with an integrating sphere whose entrance port could be rotated 90° to view either lamp position. The results presented here are limited to 1000 W quartz-halogen type lamps at ultraviolet wavelengths from 280 nm to 400 nm. Sources of uncertainty arose from the lamps, the spectroradiometer, and the lamp alignment, and increased the uncertainty in the irradiance of horizontal lamps by less than a factor of two from that of vertical NIST standard lamps. The irradiance of horizontal lamps was less than that of vertical lamps by approximately 6 % at long wavelengths (400 nm) to as much as 12 % at the shortest wavelengths (280 nm). Using the Wien radiation law, this corresponds to color temperature differences of 15.7 K and 21.3 K for lamps with clear and frosted envelopes, respectively.

Halogen lamp phototoxicity.

The radiation from quartz halogen light bulbs has been reported to cause erythema in humans and skin tumors in experimental animals. The objective of this study was to determine the relative risk of injury to humans due to the radiation from these lamps. We studied a 12-volt 50-watt quartz halogen lamp. We measured its ultraviolet output spectrum and the biological toxicity of its radiation by means of its pyrimidine dimer-inducing capability. At a 1-cm distance, the 254-nm light output of the lamp is 3 x 10(-7) W/cm2/nm. Solar radiation at this wavelength is undetectable on the earth's surface, i.e., less than 10(-12) W/cm2/nm. At 290 nm, the lamp output is approximately 3 x 10(-6) W/cm2/nm, 5,000 times greater than the summertime sun at 1 p.m. at sea level in Kuwait. The UVB and UVA output of the lamp is roughly similar to the solar output under these conditions. We also measured the pyrimidine dimer-forming potential of the lamps relative to the sun for the purpose of estimating the DNA toxicity of the lamps. At a 7-cm distance the lamp induces approximately 3.9 pyrimidine dimers/100,000 bp/min. This is approximately 4 times more rapid than that of the noontime summer sun in Michigan. We conclude that direct radiation from these lamps can cause damage to human skin, due to their UVC and UVB output. We estimate that the relative risk to keratinocyte DNA in human skin, in vivo, from exposure to the 50-watt halogen lamp at a distance of 7 cm is between 27 and 400% of the noontime summer sun in Michigan.

A Light Emitting Diode Improves Evanescent Excitation of a Fiber Optic Cocaine Biosensor

The replacement of the quartz halogen lamp of an ORD fluorometer with a high brightness blue-light-emitting diode enhanced evanescent excitation of benzoylecgonine-fluorescein bound to the mAbs immobilized on quartz fibers and gave stronger optical signals.

A Wind Tunnel for Controlled-Environment Studies of Ascospore Release byVenturia inaequalis

We designed and built a bench-top wind tunnel for the study of ascospore release by Venturia inaequalis in controlled environments. Compressed air was forced through a column of water to adjust relative humidity. Air then entered one end of a 102-mm-diameter tube at the rate of 20 liters/min, passed over a platform holding a leaf sample bearing pseudothecia of V. inaequalis, and exited the tunnel through a 2- x 10- mm orifice 20 cm downwind of the sample. Ascospores exiting the orifice impacted on a clear plastic tape borne on a clock cylinder that revolved once in 6, 12, or 24 h. Temperature of the leaf sample was recorded by a data-logger. Light was directed to the leaf sample through a fiber-optic bundle coupled to a 150-W quartz-halogen lamp. The quality and intensity of the light could be adjusted by colored or neutral density filters at the source. Simulated rain was applied to the leaf sample at the rate of 5.3 cm/h through a fine-spray nozzle located 50 cm above the sample. The temperature of the simulated rain, as well as a water jacket surrounding the tunnel, was controlled by passing the water supply through a controlled-temperature bath. The tunnel maintained temperatures as low as 1.0 ± 0.2°C for 6 h, and could operate for up to 24 h continuously. Utility of the wind tunnel and reproducibility of obtained results was demonstrated using ascospores of V. inaequalis and Guignardia bidwellii.

Characterization of modified FEL quartz-halogen lamps for photometric standards

The stability of luminous intensity and colour temperature of modified FEL-type, 1000W quartz-halogen lamps has been tested at various colour temperatures to investigate the suitability of these lamps for use as photometric transfer standards. During 60 h of operation at 2856 K, after seasoning for 100 h, the changes of luminous intensity of these lamps were 0,2% to 0,6%, and the changes of colour temperature were less than 2 K. The changes in relative spectral power distributions (normalized at 550 nm) over the 60 h of operation were within 0,5% in the visible region. The FEL-type lamps operated at 2856 K showed satisfactory stability within the limited duration of these tests. Characteristics of the lamps have also been investigated for operation at 2000 K to 3100 K, for reversed polarity, and for long-term storage.

Comparison of filter radiometer spectral responsivity with the NIST spectral-irradiance and illuminance scales

Narrowband filter radiometers are being used in the development of a new method of irradiance scale realization at the National Institute of Standards and Technology (NIST). To improve the accuracy of the current spectral-irradiance scale, we propose to eliminate several steps from the calibration process and to use the filter radiometers and a high-temperature black body in realizing the scale. Ultimately, the filter radiometers will be calibrated against a trap detector measured at the NIST High Accuracy Cryogenic Radiometer, which maintains an expanded uncertainty at 633 nm of 0,0266% for a coverage factor of k = 2. In this work, the filter and detector were calibrated as a unit using the NIST Detector Comparator Facility, and the aperture areas were measured by flux comparison with a uniform source. Six filter radiometers covering the spectral range 350 nm to 1100 nm were used to measure a known irradiance source; the measurements agreed with predictions to within 1%. Comparisons were also conducted with three NIST standard photometers, and similar agreement was observed. Since the irradiance source and the photometers were calibrated using independent methods, our results not only verify the calibration of the filter radiometers but also imply that the NIST scales of spectral irradiance and illuminance are consistent. Future plans include characterization of a high-temperature black body and the calibration of quartz-halogen irradiance lamps using this black-body source.

Neoplastic transformation of neonatal human fibroblasts exposed in vitro to radiation from a quartz‐halogen lamp

The use of unfiltered quartz-halogen lamps exposes human skin to radiation that spans much of the ultraviolet (UV) spectrum. Reports indicate that exposure to quartz-halogen lamps is erythemogenic, mutagenic, and carcinogenic. To compare the carcinogenic potential of quartz-halogen lamps with that of other UV sources, we determined the dose dependence for cytotoxicity and neoplastic transformation in neonatal human fibroblasts exposed in vitro to: a 15 W germicidal lamp (primarily 254 nm radiation), a 15 W Cool White fluorescent lamp, and an unfiltered 20 W quartz-halogen lamp. Fluence-survival relationships were multiphasic with linear dose response below about 40% survival, and all three sources produced fluence-dependent transformation as indicated by induction of anchorage-independent growth. Maximum transformation frequencies were observed at fluences of 5-8 J/m2 for the germicidal lamp, 6.3 kJ/m2 for the fluorescent lamp, and 300 J/m2 for the quartz-halogen lamp. These data confirm the carcinogenic potential of the quartz-halogen lamp.

On the Influence of Illumination During Ion Damage Defect Anneal of Silicon

AbstractAn exploratory deep level transient spectroscopy (DLTS) study on the possible role of illumination during thermal annealing has been carried out on Si with extended defects generated by Ar implantation and electron cyclotron resonance (ECR) hydrogen plasma. Experiments with rapid thermal anneal (RTA) using quartz-halogen lamps show only a minor role for illumination on anneal of defects generated by Ar ion damage as well as thermal generation of defects under post-hydrogenation anneal. However, significant differences are evident relative to conventional furnace anneal and it appears likely that recombination-assisted defect reactions may be quite significant in Si processing when high intensity sources such as arc lamps are adapted in RTA systems.

A new sunlight simulator for ecological research on plants

A new sunlight simulator was designed and built which meets the spectral and energetic requirements of experimental ecological plant research. Its radiation is generated by a combination of four commercially available lamp types: metal halide, quartz-halogen, blue and UVB fluorescent lamps. IR radiation is filtered by a layer (20 mm) of circulating water. The plant-damaging, short-wave UV radiation is eliminated by 13 mm of borosilicate glass. The total input power of the system is 40 kW. The net illuminated space for plants is 1.2 m×1.2 m×0.25 m (length×width×height). The geometric arrangement of 184 lamps, located in specially designed aluminium reflectors, and the high reflection coefficient of the aluminium walls result in diffuse incident light. Irradiances reach more than 1000 W m −2, but less than 10 −7 W m −2 below 280 nm; the measured illuminance is 102 klx; the photosynthetically active radiation (PAR, 400–700 nm) is 2200 μmol m −2 s −1. The spatial homogeneity and the temporal variation of the irradiance are satisfactory. The spectral distribution is much more similar to natural global radiation than any other simulator known. By using highly efficient and commercially available lamp types, the running costs remain low. Hence, for the first time, a simulator in the square metre range has been developed, which provides the irradiance and the temporal, spatial and spectral distribution of global radiation at an economically reasonable scale.

Thermal modeling of a calorimetric technique for measuring the emittance of surfaces and coatings

A finite element analysis model of a transient technique used to measure the emittance of surfaces and coatings was developed and used to estimate the uncertainty in emittance. The dimensions used in the model matched the dimensions used in the design of a low temperature calorimetric vacuum emissometer being built to characterize the thermal properties of space power materials in the temperature range 173–673 K. Radiant energy from a quartz halogen lamp impinged on an aluminum sample that was coated with a thermal control coating and suspended in a liquid-nitrogen-cooled vacuum chamber by narrow gauge thermocouple wires. After removing the heat source, the temperature of the sample was monitored vs. time and the temperature-time curve was used to calculate the emittance. Factors contributing to the uncertainty in the emittance included uncertainties in time, temperature, area of the sample, heat capacity of the sample and heat loss from the uncoated back side of the sample. Heat losses from the thermocouple wires were found to be negligible. The total probable error in the emittance obtained from the low temperature calorimetric vacuum emissometer design was estimated to be less than 4% for emittance values greater than 0.5 at temperatures between 173 and 673 K.

Isolation and identification of singlet oxygen oxidation products of beta-carotene.

Singlet oxygen is a highly reactive form of oxygen produced by many toxic photosensitizers. beta-Carotene quenches singlet oxygen catalytically through a very efficient physical reaction. However, concomitant chemical reactions during photosensitized oxidations consume beta-carotene. To investigate the hypothesis that chemical reactions with singlet oxygen consume beta-carotene, we characterized products of the photosensitized oxidation of beta-carotene. beta-Carotene and the photosensitizer rose bengal were dissolved in toluene/methanol (85:15 v/v), which was bubbled with O2 and illuminated with a quartz-halogen lamp for 30 min at 5 degrees C. Reaction products were analyzed by reverse-phase HPLC, UV-vis spectrophotometry, and mass spectrometry. beta-Carotene oxidation products were identified as beta-ionone, beta-apo-14'-carotenal, beta-apo-10'-carotenal, beta-apo-8'-carotenal, and beta-carotene 5,8-endoperoxide. Formation of these products was dependent on the presence of the photosensitizer. The products apparently were formed from the action of singlet oxygen rather than by photochemically-initiated beta-carotene autoxidation, since suppression of autoxidation by equimolar alpha-tocopherol did not diminish product formation. beta-Carotene autoxidation initiated by 2,2'-azobis(2,4-dimethylvaleronitrile), which generates peroxyl radicals, yielded a different product distribution than that from photosensitized oxidation. Specific products formed by singlet oxygen oxidation of beta-carotene may serve as markers for singlet oxygen quenching in biological systems.

Induction of micronuclei in cultured human lymphocytes exposed to quartz halogen lamps and its prevention by glass covers.

The light emitted by an uncovered tungsten halogen lamp (12 V, 50 W), equipped with a dichroic mirror, induced time-related and distance-related increases in the frequency of micronucleated lymphocytes following in vitro exposure. Peripheral blood lymphocytes from three healthy donors showed the same degree of sensitivity. This clastogenic effect could be ascribed to the emission of far-UV wavelengths (UVB and UVC) and was prevented by interposing a common glass cover. These results support the findings of our genotoxicity studies in repair-deficient bacteria and carcinogenicity studies in hairless mice, thereby suggesting possible health hazards associated with illumination with halogen quartz bulbs, to which an enormous number of individuals are nowadays exposed. These hazards can be simply avoided by using glass covers.

The use of visible light-curing resin for vertebral body replacement

The technology of visible light-curing resin has recently been developed for use in removable prosthodontics. A quartz halogen lamp producing a 400- to 500-nanometer wave-length spectrum of visible light is used to polymerize high-molecular-weight acrylic resin monomers. While several in vitro and in vivo studies of visible light-curing resin are found in the dental literature, no studies have yet been performed to evaluate it as an intracorporeal implant in surgery. The authors have designed a rat model of microcervical corpectomy to assess vertebral body replacement with visible light-curing resin in comparison to conventional autopolymerizing methyl methacrylate. Spinal cord function tests, spinal-implant stability assessments, and histological evaluations were made in a total of 41 rats at 2, 4, or 6 months postimplant. No animal developed a neurological deficit or radiographic instability, and at sacrifice there was no evidence of implant fracture-extrusion. In addition, there were no signs of adverse reaction in the surrounding tissues. Morphological investigation of the resin/bone interface at 6 months revealed very good implant anchorage. Visible light-curing resin was found to be far superior to methyl methacrylate for construction of spinal implants. Its waxy consistency makes it easy to handle. It remains pliable until light is applied, allowing adjustments in shape for a well-fitted implant without time constraints. Applied in layers, adjustments can be made even after polymerization of a previous layer. This new implantable resin will allow safer, immediate stabilization in patients with neoplastic destruction of the spine, and may also be advantageous for other neurosurgical applications, such as cranioplasty.

Microstructures and DC critical currents in textured Y-Ba-Cu-oxides

Sintered bars of Y-Ba-Cu oxide were partially melted using a quartz halogen lamp zone heating apparatus. The resulting multiphase samples showed varying degrees of melt texturing. It was found that the addition of YBa/sub 2/CuO/sub 5/ powders to the sintered YBa/sub 2/Cu/sub 3/O/sub 7/ prior to the zone melting process enhanced the growth of large textured grains. The best value of the critical current density was approximately 10/sup 3/ A/cm/sup 2/ at 1.0 T and 77 K for the starting composition of YBa/sub 2/Cu/sub 3/O/sub 7/-

TiSi2 formation by rapid thermal processing in a diffusion furnace

Rapid thermal processing (RTP) for the synthesis of refractory metal silicides has been in use recently. The techniques used in RTP for heating the samples include the use of a graphite strip heater and quartz halogen lamps. In the present case we have synthesized titanium disilicide (TiSi2) by RTP by using a conventional diffusion furnace. The annealing times were 90 and 180 s while the temperature of the hot zone was 800 °C (±0.5 °C) in which the sample was introduced for annealing. Auger electron spectroscopy studies of the samples indicated that there is a thin top layer of oxide of titanium with the titanium silicide buried underneath. Scanning and transmission electron microscopies were also done of the samples to ascertain surface and bulk microstructure. Measured sheet resistance of the samples is ∼1.2 Ω/sq. The present investigations thus suggest an alternative RTP technique for synthesis of silicide.

Photodynamic therapy of malignant brain tumors: clinical results of, difficulties with, questions about, and future prospects for the neurosurgical applications.

Photodynamic therapy (PDT) has been applied in a variety of oncological fields with good results. In neurosurgery, the clinical series are limited and the number of treated patients is not statistically significant. This work examines the results of PDT performed in our clinic and discusses some difficulties and causes of failure of this method in neurosurgical patients. Eight patients with malignant brain tumors underwent PDT. All had been treated previously by operation and radiation therapy and one patient had also received chemotherapy. At 24 hours after the i.v. injection of hematoporphyrin (5 mg/kg body weight), the tumor was removed as radically as possible and the residual tumor bed was exposed to either 630-nm light from an argon-dye laser or 600- to 680-nm light isolated from the emission of a quartz-halogen lamp. The type of sensitizer, the irradiation methods, and the peculiarities of glial tumors are examined as possible causes of failure. The longer survivals of some patients with glial tumors treated by PDT may make this treatment suitable when traditional therapies fail.