Powerful Lamp Research Articles

Efficiency of photodesorption of Rb atoms collected on polymer organic film in vapor-cell

The efficiency of photodesorption of Rb atoms previously collected on polymer organic film has been studied in detail. This study was carried out in a Pyrex glass cell of which the inner surface was covered with (poly)dimethylsiloxane (PDMS) film and illuminated by a powerful flash lamp. The desorption dynamic of the Rb atoms density in the cell caused by the illumination and percentage of desorbed atoms was studied by using of Rb resonance lamp and free running diode laser as sources of probing light. It was determined that 85 percent collected chemical active Rb atoms and stored during 16 s in the closed cell, 75 percent in the pumped cell can be desorbed by single flash of the lamp. The number of stored atoms decays with a characteristic time of 60 min in isolated cell and with a time 12.4 min in a pumped cell. We believe that this efficient method of collection and fast realization of atoms or molecules could be used for enhancement of sensitivity of existed sensors for the trace detection of various elements (including toxic or radioactive ones) which is important to environmental applications, medicine or in geology. The effect might help to construct an efficient light-driven atomic source for a magneto-optical trap in a case of extremely low vapor density or very weak flux of atoms, such as artificial radioactive alkali atoms.

Multispectral Image Acquisition with Flash Light Sources

We set up a multispectral image acquisition system using a flash light source and a camera featuring optical bandpass filters. The filters are mounted on a computer-controlled filter wheel between the lens and a grayscale sensor. For each filter wheel position, we fire the flash once within the exposure interval and acquire a grayscale image. Finally, all grayscale images are combined into a multispectral image. The use of narrowband filters to divide the electromagnetic spectrum into several passbands drastically reduces the available light at the sensor. In case of continuous light sources, this requires powerful lamps producing a lot of heat and long exposure times. In contrast, a flashgun emits its energy in a very short time interval, allowing for short exposure times and low heat production. Our detailed colorimetric analysis comparing the color accuracy obtainable with our flashgun and a halogen bulb shows that our acquisition system is well suited for multispectral image acquisition. We computed a mean color error of 1.75 CIE ΔE00 using the flashgun. Furthermore, we discuss several practical aspects arising from the use of flash light sources; namely, the spectrum, repeat accuracy, illumination uniformity, synchronization, and calibration of the system. To compensate for intensity variations of the flash, we propose two calibration methods and compare their performance.

Missing the Dark: Health Effects of Light Pollution

In 1879, Thomas Edison’s incandescent light bulbs first illuminated a New York street, and the modern era of electric lighting began. Since then, the world has become awash in electric light. Powerful lamps light up streets, yards, parking lots, and billboards. Sports facilities blaze with light that is visible for tens of miles. Business and office building windows glow throughout the night. According to the Tucson, Arizona–based International Dark-Sky Association (IDA), the sky glow of Los Angeles is visible from an airplane 200 miles away. In most of the world’s large urban centers, stargazing is something that happens at a planetarium. Indeed, when a 1994 earthquake knocked out the power in Los Angeles, many anxious residents called local emergency centers to report seeing a strange “giant, silvery cloud” in the dark sky. What they were really seeing—for the first time—was the Milky Way, long obliterated by the urban sky glow. None of this is to say that electric lights are inherently bad. Artificial light has benefited society by, for instance, extending the length of the productive day, offering more time not just for working but also for recreational activities that require light. But when artificial outdoor lighting becomes inefficient, annoying, and unnecessary, it is known as light pollution. Many environmentalists, naturalists, and medical researchers consider light pollution to be one of the fastest growing and most pervasive forms of environmental pollution. And a growing body of scientific research suggests that light pollution can have lasting adverse effects on both human and wildlife health. When does nuisance light become a health hazard? Richard Stevens, a professor and cancer epidemiologist at the University of Connecticut Health Center in Farmington, Connecticut, says light photons must hit the retina for biologic effects to occur. “However, in an environment where there is much artificial light at night—such as Manhattan or Las Vegas—there is much more opportunity for exposure of the retina to photons that might disrupt circadian rhythm,” he says. “So I think it is not only ‘night owls’ who get those photons. Almost all of us awaken during the night for periods of time, and unless we have blackout shades there is some electric lighting coming in our windows. It is not clear how much is too much; that is an important part of the research now.” According to “The First World Atlas of the Artificial Night Sky Brightness,” a report on global light pollution published in volume 328, issue 3 (2001) of the Monthly Notices of the Royal Astronomical Society, two-thirds of the U.S. population and more than one-half of the European population have already lost the ability to see the Milky Way with the naked eye. Moreover, 63% of the world population and 99% of the population of the European Union and the United States (excluding Alaska and Hawaii) live in areas where the night sky is brighter than the threshold for light-polluted status set by the International Astronomical Union—that is, the artificial sky brightness is greater than 10% of the natural sky brightness above 45° of elevation. Light pollution comes in many forms, including sky glow, light trespass, glare, and over illumination. Sky glow is the bright halo that appears over urban areas at night, a product of light being scattered by water droplets or particles in the air. Light trespass occurs when unwanted artificial light from, for instance, a floodlight or streetlight spills onto an adjacent property, lighting an area that would otherwise be dark. Glare is created by light that shines horizontally. Overillumination refers to the use of artificial light well beyond what is required for a specific activity, such as keeping the lights on all night in an empty office building.

Kinetics of light-cure bracket bonding: Power density vs exposure duration

Recent technologic advances make it possible to increase the light power density to reduce the necessary exposure duration. The kinetics of polymerization are complex. The special case of indirectly curing the thin layler of composite below the metallic bracket base further increases this complexity. It was hypothesized that the concept of "total energy,"--the reciprocity between power density and exposure duration--does not hold for orthodontic light-cure bracket bonding. Stainless steel brackets were bonded on deciduous bovine incisors with a standard light-cured composite. A calibrated, powerful halogen lamp allowed for modification of power density from 300 to 3000 mW/cm2. Metallic brackets were bonded in 8 groups of 20 incisors each with various combinations of power densities and exposure durations to obtain 3 levels of energy density (6000, 12000, and 24000 mJ/cm2). Another group of 20 incisors served as the positive control with a conventional powerful halogen lamp (1000 mW/cm2) for 40 seconds. After storage for 24 hours at 37 degrees C in water, the bracket shear bond strength (SBS) and the adhesive remnant index (ARI) were measured. It was confirmed that bracket SBS mainly depends on the energy density of the light cure. All groups with an energy density of 6000 mJ/cm2 had significantly lower SBS than the groups with higher energy densities (P <0.01). The dependence of SBS on exposure duration for the same energy density followed an exponential model of nonlinear regression (r2 = 0.98). The concept of "total energy" does not hold for orthodontic light-cure bracket bonding. An exposure time of less than 4 seconds, irrespective of the power density, cannot guarantee sufficient bracket bond strength. There seems to be an advantage of power density over exposure duration in the context of metallic bracket bonding. These results show that, for an efficient light-cure bracket bonding, there is an absolute lower limit of exposure duration (4 seconds) and an upper limit of useful power density (3000 mW/cm2).

Investigation of the effect of a protective layer on parameters of quartz low-pressure gas-discharge lamps with oxide electrodes

Low pressure amalgam lamps are widely used for disinfection of air and water surfaces. The application of amalgam instead of pure mercury makes it possible to design a high-efficiency powerful ultraviolet lamp and to improve the ecological impact of disinfection equipment. This paper describes the effect of oxide electrodes and a quartz inner surface on the lifetime of a lamp and on the ultraviolet-intensity reduction in low pressure lamps. We show that the burning time of the noble-gas arc discharge at a low pressure depends on the interaction between the discharge plasma and the inner quartz surface. Use of a rare-earth-metal-oxide protective layer on the inner quartz surface increases the lifetime of the lamp and prevents ultraviolet-intensity reduction in low-pressure amalgam lamps.

Flash-assist RTP for ultra-shallow junctions

This paper discusses the engineering of ultra-shallow junctions for advanced semiconductors using an annealing technique called Flash-Assist RTPTM (fRTP). This technique offers effective process times in 1–10 ms. A discussion on the evolution of rapid thermal processing (RTP) based on the thermal response time of the heat source and wafer is presented. Technical innovations required for fRTP are discussed including why an extremely powerful flash lamp is essential for this application. It is shown that a process engineer can more or less independently control diffusion and activation over a wide range, enabling the formation of junctions meeting future requirements of semiconductor manufactures.

Quantitative infrared thermography applied to blow moulding process: measurement of a heat transfer coefficient

This paper deals with the heat conditioning stage of blow moulding process applied to P.E.T bottles forming. One of the most important stage of this process is the radiative heating stage which is performed with infrared ovens using powerful halogen lamps. To validate a 3D control volume thermal software, called Plastirad, developed in our laboratory, temperatures maps were needed on the plastic preforms as well as convective heat transfer coefficient inside the oven. This measurement has been performed with two different methods : IR thermography and hot wire anemometry. These two methods are investigated and the main results are compared to focus on the interest of IR thermography.

A New Inspection Method for Plasma Facing Components

Transient thermography testing is an established method for testing the joint quality of CFC tiles in metallic heat sink systems. With this method hot pressurized water is introduced into the cooling channels of the elements and the transient heating of the CFC surface is recorded by an infrared camera. CFC tiles with a lack of bonding can be detected since they heat more slowly than well joined tiles. To perform this inspection a water flow in the tubes must be established and therefore the connection of the component to a hot water circuit is necessary. A new approach to this inspection problem is the application of lock-in thermography. With this method periodic illumination with powerful lamps of the CFC surface causes periodic heating of the CFC material. The phase shift between the periodic surface temperature evolution and the periodically operating heat source is recorded and evaluated. The lock-in thermography can be applied immediately after joining of the tiles to the component because the presence of a cooling channel system is not required for the application of this method. The method is suited to test the bonding of CFC tiles onto the component and the integrity of CFC tiles regarding possible internal cracks.

Significance of nocturnal purse seine fisheries for seabirds: a case study off the Ebro Delta (NW Mediterranean)

Seabirds are known to make extensive use of fishery waste, a phenomenon that has been particularly well studied in relation to demersal fisheries, especially when operatingduringdaylig ht hours. Contrarily, very little is known about the importance of predominantly nocturnal fisheries in providingfeedingopportunities to seabirds. We considered the particular case of purse se- iningfor small pelagic fish, which takes place basically at night, and assessed the significance of this fishing practice for seabirds off the Ebro Delta (NW Mediterranean). Fieldwork was conducted on board commercial purse seiners (nocturnal activity) in 1997-1998, and was com- plemented with observations performed on board both commercial bottom trawlers (diurnal activity; 1997- 1998) and a research vessel (1999-2000). The purse seine fleet targets small clupeoids, which are attracted and concentrated by the light of a powerful lamp, and then captured usingan encirclingnet. Purse seiners frequently changed fishing area, took very variable catches, and were strongly influenced by the weather. This made the fishery unattractive to most seabird species, which primarily at- tended purse seiners duringthe discardingprocess. This process took place on the way back to port after dawn (i.e. with daylight) during daylight and was quite irregu- lar, thus attractinglower numbers of seabirds than did trawlers. The threatened Audouin's gull Larus audouinii was the only species attendingpurse seiners reg ularly at night, capturing live fish concentrated at the sea surface duringthe haulingprocess. This is in accordance with the specialisation of this gull in the capture of epipelagic fish at night, which seems facilitated by purse seiners. Indeed, the vessels would favour the direct capture of fish (illu- mination of the sea surface, concentration of the fish), as well as the location of the shoals (light signalling). The purse seiningfishery was especially important for Aud- ouin's gull during trawling moratoria (when trawling discards were not available) and in the non-breeding season. A simple bioenergetic model estimated that in- dividual Audouin's gulls could obtain a mean of 669 kJ haul -1 , which would represent far more than half of the daily energy requirements of breeding birds. Provided that Audouin's gulls feeding in a given area could attend more than one haul in a short time, birds attendingpurse seiners at night could easily meet their energy require- ments. However, there was strongvariability in our esti- mate (from 0 to 1659 kJ bird -1 haul -1 , 95% CI), and feedingat purse seiners would only sometimes be profit- able for Audouin's gulls. Purse seine fisheries could be of importance for other nocturnal seabirds in other regions such as the SE Pacific, and this deserves further research. It is important to note that purse seiners could also be detrimental for many seabirds, through direct competi- tion and eventual depletion of fish stocks.

Especialities of Ti 3+ excitation in YAlO 3 crystals

The two-step ionization of Ti 3+ in YAlO 3 reduces the yield of Ti 3+-emission (η) at laser pumping (“Hard” pump). Stable η is found with powerful nanosecond flash lamp excitation (‘Soft’ pump). The absorption band at 280 nm was identified as a 2 T 2g → 4S transition.

Development of Large area Excimer VUV and UV Sources from a Dielectric Barrier Discharge

ABSTRACTA large-area, high power density, high efficiency, and low cost excimer VUV and UV source, which is capable of producing narrow-band radiation tunable between the near UV (λ=354 nm) and the deep UV (λ=126 nm), is described.This UV source is based on the principle that the radiative decomposition of excimer states created by a dielectric barrier discharge (silent discharge) in a rare gas, such as Ar2* (λ=126 nm), Kr2* (λ=146 nm), Xe2* (λ=172 nm) or molecular rare gas-halide complexes, such as ArCl* (λ=175 nm), KrCl* (λ=222 nm), XeCl* (λ=308 nm). Conversion efficiencies (from input electrical to output optical energy) as high as 22% can be achieved under optimum conditions. This powerful and economical lamp provides a useful UV source for low temperature photon-initiated processes and is an interesting alternative to conventional UV lamps for industrial large-scale low temperature processes. For industrial large-area processing and for the deposition of highly complex structures, these narrow band VUV and UV sources with high photon fluxes have definite advantages. Several applications of these excimer sources are reviewed, including photo-deposition of dielectric and metallic thin films, photo-oxidation of silicon, surface modification, etching of polymer, and photo degradation of pollutants.

Photolysis of 2‐azidopyridines. the behavior of 1‐(2‐azido‐6‐chloropyrid‐4‐yl)‐3‐phenylurea, a photoaffinity labeling reagent for probing cytokinin‐binding proteins

AbstractThe photolysis of l‐(2‐azido‐6‐chloropyrid‐4‐yl)‐3‐phenylurea (1) was studied under various conditions. In alcohols or in hexane, complex mixtures of products were obtained. Methoxide anions or diethylamine gave rise in high yield to 1,3‐diazepines resulting from ring enlargement of the intermediate nitrene with addition of one molecule of the nucleophile, and nucleophilic substitution of the chlorine atom. A similar reaction was observed in water, when Pyrex filtered light was used. However, with unfiltered light produced by a powerful lamp, the main reaction was photodechlorination. The reagent 1 is expected to bind covalently to cytokinin‐binding proteins through different ways upon photolysis.

UV annealing of low temperature photodeposited SiO 2 films with a new powerful lamp source

A decrease of processing temperature is essential for III–V semiconductors and in general for technology of opto-electronic devices. In this work, silicon dioxide films were deposited on Si and InP substrates using an UV-induced CVD process. SiO 2 was prepared using a SiH 4/O 2 mixture diluted in N 2, and deposition rates as high as 60 Å/min at a substrate temperature of 100°C have been obtained. The light source consists of a new xenon UV-VIS-IR lamp with wavelength ranging from 170 nm to 3 μm. This lamp offers a high luminance continous spectrum in the UV frequency range of interest (170–250 nm). With this powerful lamp coupled to a flowing all-optical reactor, the deposition temperature could be reduced to 100°C. Such a high photon fluence has also allowed for the first time to observe an effect we call “UV annealing”. In fact, direct absorption of energetic UV photons by several localized chemical structures (Si-H, OH, adsorbed water) removes the photochemical by-products of the previous reaction, and finally leads to the production of Si-O-Si bonds. The evolution of the solid-state reactions was studied in situ, using a surface-sensitive multiple internal reflection technique coupled with infrared spectroscopy (FTIR). Subsequent improvement by UV annealing of dielectric layers deposited on InP substrate was demonstrated from C( V) measurement of MIS capacitors, fabricated of these structures.

Age differences in the timing and biometrics of migrating Marsh Warblers in Kenya

Kelsey, M. G., Backhurst, G. C. & Pearson, D. J. 1989. Age differences in the timing and biometrics of migrating Marsh Warblers in Kenya. Ring. & Migr. 10: 41–47. Marsh Warblers Acrocephalus palustris migrate southwards across East Africa during November and December on a narrow migration front. Night-time trapping of migrants attracted to powerful game-viewing lamps at Ngulia Safari Lodge in Tsavo West National Park in southeast Kenya provides a unique opportunity to study numbers of active migrants in Africa. Marsh Warblers are one of the most numerous species caught. Biometric data spanning twelve years were analysed. The passage of Marsh Warblers became increasingly dominated by first-autumn birds as the season progressed. Differences in weight between individuals appeared to be largely accounted for by differences in fat reserves rather than by wing-length (as a measure of body size). Wing-lengths decreased through the season whereas body weight and fat reserves showed no seasonal change. There was n...

The photocatalysed reduction of aqueous sodium carbonate using platinized titania

Abstract Precipitated titania, prepared from TiCl 4 or TiCl 3 was photoplatinized. It was suspended in 1 M Na 2 CO 3 solution and irradiated with UV-visible (mercury lamp) or visible (xenon lamp) light. The photoproduced electrons in the conduction band of the semiconductor reduced carbonate ions to CH 3 OH (determined spectrophotometrically), carbon (determined by burning to CO 2 which was trapped and titrated), HCHO (determined spectrophotometrically by the Hantzsch reaction) and HCOO − ions (detected similarly after magnesium-HCl reduction). Doping with chromium and/or manganese ions produced lower yields of products, although the doped samples were more light absorbing than the undoped titania. Prior vacuum heat treatment of a chromium-doped sample or loading with RuO 2 necessitated longer platinization times, but neither treatment led to any significant changes in the yield of reduction products. Two anatase pigments behaved similarly in photocatalysing the reduction of carbonate. When one of these samples was irradiated with a more powerful mercury lamp, there was a marked increase in the yield of products. A tentative explanation is suggested for the observed order of yields: CH 3 OH > C > HCHO ≈ HCOO − .

Lasers: applications in radiology, January 14, 1988

In a laser, atoms, molecules or ions are raised to energetic states, for example, by the passage of a discharge current or illumination with a powerful arc lamp or another laser. These excited states can be stimulated by photons to emit additional photons which are identical in wavelength, direction and phase to the original photons. In this way, numbers of such photons may be amplified enormously to produce a parallel beam of visible, infrared or ultraviolet radiation. The principal medical lasers are the carbon dioxide laser, emitting in the far infrared, the argon laser with a blue-green beam, the Nd YAG laser with a near infrared beam, and the dye laser which may be “tuned” over a wide range of the visible and infrared spectrum. All laser beams have the property that their wavefronts are virtually parallel planes, so that they may be focused by a lens into the smallest possible spot. The applications of a particular laser depend upon the absorption and scattering properties of soft tissue at the different wavelengths available.

High-performance liquid chromatographic determination of clomiphene using post-column on-line photolysis and fluorescence detection

A method has been developed for the extraction and quantitation of the ovulatory stimulant drug clomiphene from blood plasma. The cis- and trans-isomers were separated by normal-phase chromatography using chloroform—methanol as the mobile phase. After eluting from the column, the clomiphene was passed through a PTFE photolysis coil irradiated by a powerful UV lamp, resulting in conversion of the isomers to highly fluorescent species. The derivatised material was then detected using a fluorescence spectrometer. Use of this method enables a substantial improvement in sensitivity over UV detection and has permitted the measurement of plasma clomiphene levels in patients receiving clomiphene therapy.

A comparison of radiation and photochemical crosslinking of polyethylene

ONE of the most effective methods of modifying polyethylene (PE) for the pur: pose of increasing its heat resistance, its resistance to organic solvents, and other technically valuable properties is to subject it to radiation crosslinking [1]. I t has been shown more recently that ultraviolet light energy can be used for crosslinking PE and other polyolefins [2]. In a number of instances by the use of powerful ultraviolet lamps it is possible to obtain the same crosslinking effect in PE as can be attained with complex, expensive sources of ionizing radiation. Unfortunately no comparative studies of special features of radiation and photochemical crosslinking of PE have been reported in the literature. The absence of this information hinders the correct assessment and selection of the method of modification of different objects.

Tumoricidal effect of laser energy on experimental and human malignant tumors.

LASER is an acronym for Light Amplification by the Stimulated Emission of Radiation. Amplification itself may be characterized as a controlled release of stored energy. Townes and Schawlow developed the theory of the optical maser or laser in 1958. T. H. Maiman, in May, 1960, built the first operational solid-state laser utilizing a synthetic ruby crystal. As a first step in ruby laser operation, capacitor banks are charged with electric energy to provide an intense, brief light flash from powerful xenon-arc lamps. Trivalent chromium atoms in the ruby crystal whose end faces have been highly silvered, absorb and reradiate energy . . .

An improved p-nitrophenol method for estrogen determination employing a commercial fluorimeter

1. 1. The peak excitation and fluorescence wavelengths for acid-activated estrogens (Ittrich method) were determined with a powerful xenon arc lamp, a monochromator, and the Beckman DK-1 spectrophotometer. The values were respectively 537 and 550 mμ, close to Ittrich's values obtained with less suitable equipment. 2. 2. Chloroform was found to be the solvent of choice. 3. 3. On reading the fluorescence of such solutions at room temperature, the fluorescing power of the estrogens was found to fall off rapidly with time, as was observed previously with the Slaunwhite-Engel system in this laboratory. 4. 4. For routine determinations, the Farrand fluorimeter could be used with either micro- or macrocuvettes and the filter system primary 546 mμ (interference)/secondary 585 mμ (interference) + 600 (glass). Scattered light was negligible with this system. 5. 5. Fluorescence readings by the time-lapse method were more specific than absorbance readings with the Allen correction applied on analyzing certain tissue extracts containing highly hydrophilic material. 6. 6. Use of internal standards, to be added to an aliquot of the extract, is recommended. 7. 7. The variation with temperatures noted by Ittrich was also observed and, in agreement with Breuer and Gertz, it is recommended that the experimental conditions be closely controlled. 8. 8. The Ittrich procedure is a useful tool because of elimination of some impurities (held in the aqueous phase) and because it gives a more consistent fluorescence for the spectrum of known estrogens.