High-intensity Light Source Research Articles

Characterization of Schlieren Light Source Using Laser -Induced Optical Breakdown in Argon

Introduction S CHLIEREN imaging systems are widely used for both qualitative and quantitative flow visualization in compressible flows and active index of refraction flowfields such as two-index mixing problems or combustion flowfields. A common implementation of schlieren imaging uses a pulsed light source to provide instantaneous measurements in unsteady flowfields. A variety of pulsed light sources has been used in the past with schlieren imaging systems, including arc lamps, incandescent bulbs, flash tubes, spark gaps, and light-emitting diodes.1 Lasers have been used to provide a narrow linewidth illumination source, which is useful for filtering broad spectral emissions from plasmas or flames, but at the cost of image degradation due to laser speckle. A recent technical note described the use of a laser-induced spark as a point source, which could be inserted in the flowfield avoiding the need to integrate through the density fluctuations associated with the boundary layers on the wind-tunnel walls.2 Recent papers have also described the use of a laser-induced spark as a light source for schlieren imaging in a plasma flow3 and an exploding wire bridge,4 both applications that benefit from a very high-intensity schlieren light source. Our objective in this Technical Note is to characterize a laserinduced spark schlieren imaging technique that provides a very highintensity light source, with short time duration and with repeatable temporal and spatial characteristics. Spatial and temporal variations in intensity are reported for this light source, as well as a comparable light source using a laser discharge in air. This light source has

Measuring the thickness of clear freshwater ice using geometric optics and a spectrometer

An instrument 1 1 Patent pending. which exploits geometric optics was devised to measure the thickness of slabs of optically transparent material such as Plexiglas or freshwater ice using a high-intensity light source. The apparatus consisting of a prism, a micrometer single-axis translation stage, and an optical spectrometer measures the spatial span between two chosen Fraunhofer line wavelengths in the prism-refracted visible spectrum reflected through the test slab. This span was found to be proportional to slab thickness. Measurements were made on various thicknesses of Plexiglas sheets ranging from 8 to 49 mm thick as well as nearly-bubble-free macrocrystalline freshwater ice in the thicknesses ranging from 28 to 53 mm thick. Results indicated a linear relationship between spectral span and slab thickness. This device may be suitable for detecting and measuring point-location ice thickness on aircraft wings, as well as for other industrial and research purposes.

High-intensity Low-pressure Electrodeless Mercury-Argon Lamp for UV Disinfection of Wastewater

Recently, ultraviolet (UV) radiation has been applied as a disinfection method for wastewater treatment plants. A high-intensity and high-power UV light source is required in the field of bacilli sterilization. The electrodeless UV lamp turns on by delivering RF-frequency power from the power supply through the matching circuit into the induction coil around the lamp. The electric current passing through the induction coil generates a magnetic field. The gas sealed inside the lamp is excited and ionized by the magnetic field, and so discharge of the gas occurs and light is emitted. Thus the discharge produces UV emission. Using RF frequency power circuit technology and optimizing UV lamp shape, we have made it possible to input power of 500W to a 500mm-length luminescent lamp. Moreover, an over 30% rate of UV radiating efficiency has been obtained. It realizes a high-intensity and high-power ultraviolet light source. Optimization of water current path in the sewage effluent disinfection has realized a colon bacillus removal ratio of 99.9%.

Controlled Ablation of Microtubules Using a Picosecond Laser

The use of focused high-intensity light sources for ablative perturbation has been an important technique for cell biological and developmental studies. In targeting subcellular structures many studies have to deal with the inability to target, with certainty, an organelle or large macromolecular complex. Here we demonstrate the ability to selectively target microtubule-based structures with a laser microbeam through the use of enhanced yellow fluorescent protein (EYFP) and enhanced cyan fluorescent protein (ECFP) variants of green fluorescent protein fusions of tubule. Potorous tridactylus (PTK2) cell lines were generated that stably express EYFP and ECFP tagged to the α-subunit of tubulin. Using microtubule fluorescence as a guide, cells were irradiated with picosecond laser pulses at discrete microtubule sites in the cytoplasm and the mitotic spindle. Correlative thin-section transmission electron micrographs of cells fixed one second after irradiation demonstrated that the nature of the ultrastructural damage appeared to be different between the EYFP and the ECFP constructs suggesting different photon interaction mechanisms. We conclude that focal disruption of single cytoplasmic and spindle microtubules can be precisely controlled by combining laser microbeam irradiation with different fluorescent fusion constructs. The possible photon interaction mechanisms are discussed in detail.

Physical compatibility of pemetrexed disodium with other drugs during simulated Y-site administration

The physical compatibility of pemetrexed disodium with selected other drugs during simulated Y-site injection was studied. A 5 mL sample of pemetrexed disodium 20 mg/mL in 0.9% sodium chloride injection was combined with 5 mL of a solution of each of 79 other drugs. The other test drugs included antineoplastics, antiinfectives, and supportive care drugs used undiluted or diluted in 0.9% sodium chloride injection or 5% dextrose injection. Visual examinations were performed with the unaided eye in normal diffuse fluorescent light at intervals up to four hours after mixing. Combinations with no obvious incompatibility were examined further with a high-intensity monodirectional light source to enhance visualization of small particles and low-level turbidity. The combinations were also evaluated with a turbidimeter at one and four hours. All combinations without visual incompatibility were assessed with a particle sizer-counter. Of the 79 pemetrexed-secondary drug combinations, 55 were compatible for at least four hours. However,mixture with 24 drugs resulted in precipitation (including microprecipitation) and color change. Pemetrexed disodium was incompatible with 24 drugs during simulated Y-site administration and should not be administered with them.

Design and performance of a light-emitting diode detector compatible with a commercial capillary electrophoresis instrument.

Indirect photometric detection in capillary electrophoresis (CE) has been predominantly performed in the UV region, in part due to a lack of suitable high-intensity and low-noise light sources in the visible spectral region. A new photometric detector based on light-emitting diodes (LEDs) as light sources and compatible with a commercially available CE instrument has been designed and constructed and its performance evaluated. The utility of this detector was successfully demonstrated by the indirect photometric detection of anions using a dye as probe and absorbance measured in the visible region. The detector exhibited very low baseline noise (around 0.03 mAU), stable output, and improved upper limit of detection linearity (502 mAU) compared with previously used LED detectors. The detector was tested for indirect detection of anions separated with an electrolyte containing 4 mM Orange G as the indirect detection probe, 10 mM histidine as an isoelectric buffer, and 0.05% hydroxypropylmethylcellulose to suppress the electroosmotic flow. Extremely low detection limits were obtained ranging from 0.16-0.36 microM (excluding chloride 0.56 microM), with separation efficiencies in the range of 154,000-274,000 theoretical plates.

High-intensity far-infrared light source using the coherent transition radiation from a short electron bunch

The characteristics of the far-infrared coherent transition radiation light source used for absorption spectroscopy have been investigated. A single-bunch electron beam of an L-band linear accelerator has been used in the experiments. The energy and the electron charge in a bunch of the beam have been 27 MeV and 13.5 nC/bunch, respectively. The accelerator has been operated to obtain high-intensity radiation. The spectrum of the coherent transition radiation from the beam has been measured at wavelengths of 0.4–2 mm and the electron bunch form factor has been given from the spectrum. For the typical geometrical configurations of the light source the light spectrum has been obtained by using the bunch form factor. The characteristics of the light source have been compared with those of the coherent synchrotron radiation.

High-intensity far-infrared light source using the coherent transition radiation from a short electron bunch

The characteristics of the far-infrared coherent transition radiation light source used for absorption spectroscopy have been investigated. A single-bunch electron beam of an L-band linear accelerator has been used in the experiments. The energy and the electron charge in a bunch of the beam have been 27 MeV and 13.5 nC/bunch, respectively. The accelerator has been operated to obtain high-intensity radiation. The spectrum of the coherent transition radiation from the beam has been measured at wavelengths of 0.4–2 mm and the electron bunch form factor has been given from the spectrum. For the typical geometrical configurations of the light source the light spectrum has been obtained by using the bunch form factor. The characteristics of the light source have been compared with those of the coherent synchrotron radiation.

IPL technology: a review.

Intense pulsed light (IPL) systems are high-intensity light sources, which emit polychromatic light. Unlike laser systems, these flashlamps work with noncoherent light in a broad wavelength spectrum of 515-1,200 nm. These properties allow for great variability in selecting individual treatment parameters and adapting to different types of skin types and indications. The purpose of this article was to critically review international medical publications of the many indication in which IPL technology can be used, including our own evaluations and experiences. The range of therapeutic uses for high-intensity flashlamps was reviewed, ranging from benign cavernous hemangiomas, benign venous malformations, essential telangiectasias, leg telangiectasias, poikiloderma of Civatte, and port-wine stains to pigmented lesions, cosmetically undesired hypertrichosis, and facial rhydids. The relative benefits and risks were discussed in detail and compared with other laser systems. Because of the wide spectrum of potential combinations of wavelengths, pulse durations, pulse frequency, and fluences, a great deal of experience is required when using IPL technology. Proper patient selection and critical diagnostics serve to keep the adverse effects of the treatment to a minimum. The distinctive technical conditions involved combine to make IPL technology an alternative and auxiliary treatment option to existing laser systems and conventional therapies.

Effect of variable light intensity on composite shrinkage

Statement of problem. Polymerization shrinkage is a critical limitation of dental composites and may contribute to postoperative pain, tooth fracture, microleakage, and secondary caries. Polymerization with high-intensity light sources has been related to increased depth of cure and improved mechanical properties. However, high-intensity light initiation has also been associated with greater polymerization shrinkage. Purpose. The purpose of this study was to investigate the effect of sequentially increasing light intensity on the polymerization shrinkage of 2 composites, a hybrid and a microfil. A Knoop hardness test was used to evaluate effectiveness of the cure with each intensity increase. Material and methods. Four groups of 12 samples were measured for polymerization shrinkage by using a linometer. Light intensity curing sequences were as follows: full-intensity control (100% intensity for 40 seconds), low-intensity control (25% intensity for 40 seconds), test group 1 (25% intensity for 20 seconds, 50% for 10 seconds, 100% for 10 seconds), and test group 2 (25% intensity for 10 seconds, 50% for 10 seconds, 100% for 20 seconds). Statistical comparisons were made using a 1-factor ANOVA and a Tukey multiple comparisons test within each material. Results. Results showed a significant difference (P<.05) in mean linear shrinkage between the full-intensity control group and the other 3 sequences for both composites. No difference existed within the other 3 groups for either composite. Knoop hardness was similar for the full-intensity control and test group 2. The low-intensity control group and test group 1 were also similar but significantly lower. Conclusion. Curing composites for 10 seconds at 25% intensity, 10 seconds at 50%, and 20 seconds at 100% significantly reduced polymerization shrinkage while not compromising depth of cure. (J Prosthet Dent 2000;84:499-505.)

Compatibility Screening of Linezolid Injection during Simulated V-Site Administrationl with Other Drugs and Infusion Solutions

To evaluate the physical compatibility of linezolid injection (Zyvox-Pharmacia) during simulated Y-site administration with 8 infusion solutions and 110 selected other drugs. Controlled experimental trial. Laboratory. Five-milliliter samples of linezolid injection 2 mg/mL were mixed with 5 mL samples of the selected infusion solutions and the selected other drugs diluted in 5% dextrose injection, or, if necessary to avoid incompatibility with the diluent, 0.9% sodium chloride injection. Visual examinations of the samples were performed in normal fluorescent light with the unaided eye and using a Tyndall beam (high-intensity monodirectional light source) to enhance visualization of small particles and low-level haze. The turbidity of each sample was measured, and for samples that did not exhibit visible precipitation, the particle content was measured, as well. All of the samples were assessed initially and at 1 and 4 hours. All of the infusion solutions and most of the test drugs were physically compatible with linezolid injection during the 4-hour observation period. Physical incompatibilities resulted when linezolid injection was combined with five of the drugs: amphotericin B, chlorpromazine hydrochloride, diazepam, pentamidine isethionate, and phenytoin sodium. Precipitation, turbidity formation, and/or unacceptable changes in measured haze levels were observed. Linezolid 2 mg/mL was physically compatible for 4 hours at room temperature with all 8 infusion solutions tested and 105 of the drugs tested. Simultaneous Y-site administration of linezolid injection with the five drugs resulting in physical incompatibilities should be avoided.

High-Intensity Low-pressure Electrodeless UV Lamps for The Sewage Effluent Disinfection System

High-Intensity Low-pressure Electrodeless UV Lamps for The Sewage Effluent Disinfection SystemRecently, ultraviolet (UV) radiation has been applied as a disinfection method on the sewage treatment works. A high-intensity and high-power UV light source is required in the field of bacilli sterilization. Using RF frequency power circuit technology and optimizing UV lamp shape, we have made it possible to input power, 500W, to a 500mm-length luminescence lamp. Moreover, a 30% maximum rate of...Author(s)Shinji KobayashiAkinori HatanoYoshio NakayamaSourceProceedings of the Water Environment FederationSubjectSession 62 - Facility Operations I: UV DisinfectionDocument typeConference PaperPublisherWater Environment FederationPrint publication date Jan, 2000ISSN1938-6478SICI1938-6478(20000101)2000:8L.162;1-DOI10.2175/193864700784546873Volume / Issue2000 / 8Content sourceWEFTECFirst / last page(s)162 - 168Copyright2000Word count115

Angioscopy-assisted aneurysm clipping.

To test the concept that endovascular angioscopy can assist surgical intracranial aneurysm clipping by providing an endoluminal view of the aneurysm-parent vessel complex. A carotid bifurcation aneurysm was surgically created in a dog at the lingual artery origin. A balloon catheter was inflated proximal to the aneurysm to block proximal blood flow and allow endoluminal visualization. A flexible angioscope connected to a video monitoring system and to a high-intensity light source was then advanced within the catheter lumen and positioned immediately distal to the catheter tip. The aneurysm neck was clipped, and the clip was repositioned several times along the neck, with or without distal parent vessel compromise. Each time, the endovascular image on the monitor was interpreted by an observer blinded to the position of the clip. Clip position and image interpretation were communicated independently to a third person, who analyzed the correlation between them. Angioscopy allowed clear visualization of the extent of aneurysm neck occlusion (complete, incomplete, residual "dog ear") after clip application, as well as the presence or absence of distal parent vessel compromise. Aneurysm neck configuration, size, presence of thrombus, and suture line definition were depicted. Critical structures external to the aneurysm-parent vessel complex were transilluminated by the high-intensity lamp. Although acknowledged as the treatment of choice for intracranial aneurysms, surgical exclusion can be accompanied by significant morbidity related to perforator occlusion, parent artery compromise, and/or persistent residual aneurysm. The availability of a device allowing visualization of an aneurysm from an endoluminal perspective theoretically could reduce the incidence of these complications. Angioscopy has the potential to become a useful adjunct during intracranial aneurysm clipping because it provides real-time endoluminal viewing of the aneurysm-distal parent vessel complex, which is sometimes obscured to the surgeon.

Effectiveness of polymerization of a prosthetic composite using three polymerization systems

Statement of problem. Although properties of laboratory-polymerized composite materials are influenced by the type of polymerizing unit, little information is available regarding the comparison between use of a high-intensity light source and application of secondary heat treatment. Purpose. This study examined properties of a prosthetic veneering composite polymerized with 3 polymerizing systems to evaluate the effects of varying polymerization modes on hardness, solubility, and depth of cure. Material and methods. A composite material designed for a prosthetic veneer (Conquest Crown and Bridge) was polymerized using 3 methods: (1) exposure in the proprietary photopolymerizing unit with 2 halogen lamps (Cure-Lite Plus), followed by heating in an oven (Conquest Automatic Curing Unit); (2) exposure in a photopolymerizing unit with a xenon stroboscopic light source (Dentacolor XS); and (3) exposure in a photopolymerizing unit with 2 metal halide lamps (Hyper LII). Knoop hardness, water solubility, and depth of cure were determined for groups of 5 specimens, according to standardized testing methods. Data were compared using analysis of variance and the Duncan new multiple range test ( P <.05). Result. The hardness number generated with the metal halide unit was statistically greater than those produced by the other 2 methods, and material component released into water was minimal when the material was exposed with the metal halide unit ( P <.05). Among the 3 photopolymerizing units, the metal halide unit consistently exhibited the greatest depth of cure. Conclusion. Certain properties generated with the use of the high-intensity polymerizing unit exceeded those obtained from a proprietary system that requires a postheat treatment. (J Prosthet Dent 1999;82:336-40.)

Transillumination blisters in a neonate

Transillumination with a high-intensity fiberoptic light source is an effective means of diagnosing pneumothoraces and localizing arteries and veins for blood sampling. It has been used for these purposes in neonatal intensive care units since the 1970s. Thermal burns were reported in association with the technique initially, but this complication now occurs infrequently because of numerous safety precautions. We present a case of thermal blisters induced by transillumination in a neonate. This entity is an important addition to the differential diagnosis of vesicobullous eruptions in the neonate. (J Am Acad Dermatol 1999;41:264-5.)

High Intensity UV Emission from Cold-Cathode Mercury-Argon Lamps

A high-intensity UV light source is required in the fields of bacilli sterilization, material processing and so on. When a continuous sinusoidal voltage waveform is applied between the electrodes of a mercury-argon lamp, the UV emission shows saturation effect because of the presence of a resonance line of mercury. We tried to control the plasma condition by using a pulsed power supply. The cold-cathode mercury-argon lamp used was 180 mm long and 6.0 mm in diameter. A square-like pulsed waveform whose frequency and duration were 70 kHz and 5 µs, respectively, was alternately applied between the electrodes. As a result, the 254 nm UV emission intensity was achieved, which was 30-fold that obtained by applying 30 kHz continuous sinusoidal waveform.

The early fluidic and optical physics of cytometry.

All forms of cytometry, depend on the basic laws of physics, including those of fluidics, optics, and electronics, most of which were established centuries ago. Flow cytometry depends critically on the fluidics presenting each individual cell with precision to the sensing volume. This is intersected by a high-intensity light source, and light scattering and fluorescence from suitably stained constituents in each cell are captured by the light-collecting optics and measured. The works and observations of Bernoulli and Euler in the 18th century, Reynolds in the 19th century, and Crosland-Taylor in the 20th century in the field of fluid dynamics laid the foundations for hydrodynamic focussing, which is the primary prerequisite for presenting individual cells to the sensing volume. In addition, electrostatic cell sorters must have the ability to generate stable droplet formation in the jet-stream issuing from the flow chamber nozzle. The origins here can be traced to work carried out in the early to mid-19th century by Savart, Magnus, and Thomson. Flow, image, and confocal cytometry are all dependent on the laws of optics, including those of reflection and refraction as well as numerous other optical principles. The observations and works of Socrates, Ptolemy, Snel, and Descartes between about BC 370 and 1637 were of seminal importance in developing the laws of reflection and refraction. In the mid-17th century Hooke illustrated the power of magnifying glasses and microscopy in his Micrographia and Newton was responsible for explaining colours in the spectrum. Huygens, toward the end of the 17th century, put forward the concept of point source light propagation contributing to a wave front. Finally, Thomas Young, early in the 19th century, established the wave form of light from interference patterns. Most people will be familiar with some of these discoveries and the investigators who carried out the work; some people will be familiar with all of these. However, very few people are likely to have had the opportunity and privilege to access the very early works and the original data and manuscripts, or translations thereof, which laid the foundations of physics that enabled our discipline to be established. It is always important for any discipline to remember its roots and to appreciate the seed from which those roots grew, for it is much easier to learn and fully understand when we have a knowledge of the source and the logical progressions that lead from one discovery to the next. This knowledge lends perspective to our current endeavours as the past, after all, created the present, which in turn contributes to the future. In this article, which was presented as an invited lecture at the 9th Canadian Consensus meeting on AIDS, I have attempted to trace the origins of the early work on the physics of fluidics and optics, which laid the foundations.

Solution Structure of Porcine Delta Sleep-inducing Peptide Immunoreactive Peptide A Homolog of the ShortsightedGene Product

The 77-residue delta sleep-inducing peptide immunoreactive peptide (DIP) is a close homolog of the Drosophila melanogaster shortsighted gene product. Porcine DIP (pDIP) and a peptide containing a leucine zipper-related partial sequence of pDIP, pDIP(9-46), was synthesized and studied by circular dichroism and nuclear magnetic resonance spectroscopy in combination with molecular dynamics calculations. Ultracentrifugation, size exclusion chromatography, and model calculations indicated that pDIP forms a dimer. This was confirmed by the observation of concentration-dependent thermal folding-unfolding transitions. From CD spectroscopy and thermal folding-unfolding transitions of pDIP(9-46), it was concluded that the dimerization of pDIP is a result of interaction between helical structures localized in the leucine zipper motif. The three-dimensional structure of the protein was determined with a modified simulated annealing protocol using experimental data derived from nuclear magnetic resonance spectra and a modeling approach based on an established strategy for coiled coil structures. The left-handed super helical structure of the leucine zipper type sequence resulting from the modeling approach is in agreement with known leucine zipper structures. In addition to the hydrophobic interactions between the amino acids at the heptade positions a and d, the structure of pDIP is stabilized by the formation of interhelical i to i' + 5 salt bridges. This result was confirmed by the pH dependence of the thermal-folding transitions. In addition to the amphipatic helix of the leucine zipper, a second helix is formed in the NH2-terminal part of pDIP. This helix exhibits more 310-helix character and is less stable than the leucine zipper helix. For the COOH-terminal region of pDIP no elements of regular secondary structure were observed.

High pressure discharges in cavities formed by microfabrication techniques

High pressure discharges are the basis of small high intensity light sources. In this work, we demonstrate the formation of high pressure discharges, in cavities formed by applying micromachining and integrated circuit techniques to quartz substrates. Cavities containing varying amounts of mercury and argon were fabricated to obtain high pressure discharges. A high pressure mercury discharge was formed in the electrodeless cavities by exciting them with a microwave source, operating at 2.45 GHz and in the electroded cavities by applying a dc voltage. The contraction of the discharge into a high pressure arc was observed. A broad emission spectrum due to self-absorption and collisions between excited atoms and normal atoms, typical of high pressure mercury discharges, was measured. The light output and efficacy increased with increasing pressure. The measured voltage was used to estimate the pressure within the electroded cavities, which is as high as 127 atm for one of the two cavities discussed in this work. Efficacies over 40 lumens per watt were obtained for the electrodeless cavities and over 50 ℓm/W for the electroded cavities.

Atoms as many-body systems

Some personal recollections: It is my pleasure to present this article in the volume, dedicated to the 70th birthday of Academician S.T. Belyaev. I have known him personally since 1961 and admire his profound contributions to the theory of Bose-liquids, to the theory of superconductivity of atomic nuclei and some other important scientific works. He is well known also as an organizer of science and education. For years he was, and is still the Chairman of the Synchrotron Radiation Commission of the Russian Academy of Science, a body which was established long ago to promote construction of high intensity light sources, and technological as well as scientific research using this light. One of the important directions of this study is investigation of photoabsorbtion by multielectron atoms in order to obtain information about their structure. S.T. Belyaev strongly supported this direction, which gives me the right to choose as a title of my contribution “Atoms as Many-Body Systems”.