Flashlamp Radiation Research Articles

Treatment of Extra-gingival Pyogenic Granuloma (<i>Athara ratthathontham</i>) in Siddha – A Case Report

The present case report was a 36-year female with lesion on the right side of inner lower lip and diagnosed as pyogenic granuloma occurring at an unusual site. The presently available treatment for pyogenic granuloma is surgical excision which might delay the wound healing due to complications such as intraoperative bleeding and post operative infection. Other treatment modalities such as cryosurgery, CO2 and Nd:YAG lasers, flash lamp pulsed dye lasers, surgical ablation, and radiation may not be affordable for many patients. In our present study, the Siddha para-surgical therapy chuttigai (cauterization) was performed and the case was followed up for 30 days. The intervention was found to be as a simple, inexpensive therapy effective in treating small superficial pedunculated vascular lesions with no blood loss or no need of hospitalization.

DEVELOPMENT OF LONG PULSED ND:YAG LASER SYSTEM

The Nd:YAG laser with long pulse duration can be produce by using an appropriate pumping scheme. The purpose of this study is to construct a high voltage power supply for laser system. In this attempt multiple-mesh pulse forming technique was performed to obtain electrical pump pulses with a more rectangular shape and long normal-mode laser pulses at constant power. The flashlamp driver was designed with variable input energy. The developed flashlamp driver composes of five major electronic circuits. There are comprised of signal controller device, simmer power supply (SPS), trigger pulse ignition circuit, capacitor charging power supply (CCPS) and multiple-mesh LC pulse forming network (MPFN). The construction of the flashlamp driver is started by designing a signal controller. The controller generated a small voltage to activate the electronic components such as silicon controlled rectified (SCR) and transistor. The ignition circuit was used to ignite xenon gases which responsible to form ionized spark streamer between the two electrodes of flashlamp. A Low dc current was induced by the simmer power supply to sustain the flashlamp in simmering mode. The capacitor charging power supply was used to supply electrical power to capacitor bank within specific time. Nd:YAG laser oscillator was aligned and pumping by the new developed flashlamp radiation. As a result Nd:YAG laser beam was generated having fundamental wavelength of 1064 nm and 650 microsecond of pulse duration with maximum output energy of 250 mJ.

The Pumping Parameters for Er-Doped Tellurite Glass

Erbium doped tellurite glass rod of the 78.5 TeO2 20 ZnO 1.5 Er2O3 where has successfully been fabricated as lasing medium and have been investigated by means of their properties needed in lasing application. The external triggering method is used to generate high peak current in several microsecond pulse duration. The external triggering circuit design consists of power supply, discharge capacitor, control unit, pulse forming network and ignition circuit. This driver operates in single mode pulse that can be adjusted corresponding to the controller which can vary from 650V to 1000V. The operation is started initially with an external trigger pulse which is the voltage pulse of 8kV with pulse duration 20.0μs. The connection operated by trigger thrystor (SCR) as a switch and ionized gaseous inside the lamp. After the gaseous breakdown, the current from the capacitor flows continuously through the flashlamp. The output current is initially increased proportion in order to the input energy. Maximum value of peak current flashing at 888A with higher input energy, while, the increasing voltage is not linearly increased with the input energy. From the plotted graph of current and voltage, V-I, shows a nonlinear relationship with the electrical input energy. The developed flashlamp driver has produced about 87% in efficiency while another 13% is lost in the circuit resistance. Flashlamp radiation is detected by using spectrometer in the range of 200nm to 1000nm. The beam is used to excite the erbium glass medium and a coherent beam of 1550nm wavelength is produced.

Precise millisecond annealing for advanced material processing

AbstractFlash lamp annealing (FLA) reduces the thermal budget on the bulk and thus hinders undesired thermal diffusion. For reliable process control, however, a temperature measurement concept is needed that is capable of facing the high radiation background of the flash lamps and the millisecond detection regime at the same time (Reichel et al., Crit. Rev. Solid State Mater. Sci. 36, 102 (2011) [1]). A new concept has been developed for precise in‐situ temperature measurement during flash‐lamp millisecond annealing. There has been taking advantage of FLA for various applications. Implantation and subsequent FLA were used to obtain III‐V semiconductor quantum dots on silicon pillars (Prucnal et al., Nano Lett. 11, 2814 (2011) [2]). The same procedure was applied to achieve superconductivity with conventional silicon technolog (Fiedler et al., Phys. Rev. B 83, 214504 (2011) [3]). FLA was further used for advanced doping of “dirty‐silicon” solar cells. The short annealing cycles allow for successful dopant activation while undesired metal impurities remain electrically inactive (Prucnal et al., Acta Phys. Pol. A 120, 192 (2011) [4]). These examples show that in‐situ process control is required to make sure the major advantage of millisecond annealing is not narrowed by unreliable temperature measurement. In this contribution, a method will be presented that satisfies this issue by in‐situ distinction between thermal and flash lamp radiation (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Radiative Properties of Patterned Wafers With Nanoscale Linewidth

Abstract Temperature nonuniformity is a critical problem in rapid thermal processing (RTP) of wafers because it leads to uneven diffusion of implanted dopants and introduces thermal stress. One cause of the problem is nonuniform absorption of thermal radiation, especially in patterned wafers, where the optical properties vary across the wafer surface. Recent developments in RTP have led to the use of millisecond-duration heating cycle, which is too short for thermal diffusion to even out the temperature distribution. The feature size is already below 100nm and is smaller than the wavelength (200-1000nm) of the flash-lamp radiation. Little is known to the spectral distribution of the absorbed energy for different patterning structures. This paper presents a parametric study of the radiative properties of patterned wafers with the smallest feature dimension down to 30nm, considering the effects of temperature, wavelength, polarization, and angle of incidence. The rigorous coupled wave analysis is employed to obtain numerical solutions of the Maxwell equations and to assess the applicability of the method of homogenization based on effective medium formulations.

Lichen removal from Chinese Spirit Path figures of marble

High-intensity pulsed light from a portable xenon flashlamp system was employed to remove lichen growth from Ming-dynasty statues located in the Seattle Art Museum sculpture garden. The ultraviolet and visible flashlamp radiation was found to decompose the lichens on the friable marble of the statues without damaging the stone. Thus, a non-chemical, non-mechanical, and non-abrasive divestment technique has been demonstrated for the conservation of artistic sculpture. The high efficiency and low cost of flashlamp systems makes this a cost-effective alternative to laser cleaning.

Coating ablation and surface modification by pulsed light radiation

Abstract The harnessing of light energy for industrial and commercial applications has expanded enormously in the last 30 years, i.e. since the invention of the laser. In the surface preparation field, significant laser applications include surface divestment (coatings, corrosion and contamination), annealing and glazing. In many instances, widespread commercial implementation of laser surface processing is impeded by cost-effectiveness issues. A more efficient alternative is described, which employs xenon flashlamp (rather than laser) radiation for surface preparation. The results of xenon flashlamp processing are presented. In certain instances, post-irradiation surfaces exhibit improved coating adhesion and resistance to corrosion. Finally, an advanced pinchlamp source with potential applications in the field of nuclear decontamination is discussed.

Low-threshold lasing of LiYF4:Pr3+crystals in the 0.72 μm range as a result of flashlamp pumping at 300 K

Low-threshold stimulated radiation emitted by Pr3+ ions in an LiYF4 crystal was observed for the first time at 300 K when the crystal was pumped by flashlamp radiation. The wavelength of the emitted radiation was 0.7206 μm and it was due to the 3P0→3P4 transition.

Excitation of NaF:F2+by flashlamp pump radiation converted by fluorescence

Stimulated emission from an NaF:F2+ crystal was excited by pumping with xenon flashlamp radiation and converting its ultraviolet component to the absorption band of the F2+ color centers using a solution of an organic dye C-102 and a crystal tube made of Al2O3:Ti3+. Lasing was obtained from all the active media inside the enclosure, so that a laser of this type could be used as a polychromatic spectrum analyzer.

Kinetics of the photodissociation iodine laser with slow pumping

Systematic calculations of maximum inversion were performed for iodine photodissociation laser in dependence on the mixture composition. The flash-lamp radiation was modelled as emanating from an optically thin Xe plasma. Duration of the pumping pulse is about 300 μs. The sensitivity of the model to the values of kinetic constants was also tested.

Theoretical analysis of the kinetics of a laser utilizing a mixture of O2(1Δ) and an iodine aerosol

Calculations are made of the gain of the active medium and the specific output power of a pulsed laser utilizing a mixture of O2(1?) and an iodine aerosol. It was found that, in principle, lasing could be achieved without external initiation due to self-heating of the mixture accompanying relaxation of some of the stored energy. However, as a result of scattering of light by iodine particles and energy losses due to heating of the mixture, the specific output energy is low (~ 4 J/liter). The laser energy characteristics can be improved appreciably (up to 11 J/liter) by rapid evaporation of iodine particles using external radiation. An estimate of the electrooptic efficiency of a laser utilizing evaporation of iodine particles by flashlamp radiation gives a value of ~ 800%.

Energy parameters of lasers utilizing erbium glasses sensitized with ytterbium and chromium

An experimental investigation was made of the effect of sensitizing ytterbium- and erbium-activated lead barium phosphate glasses with Cr3+ ions on the energy parameters of lasing due to the 4I13/2 — 4I15/2 transition in Er3+ ions (λ1 = 1.54 μ). It was found that substantial sensitization was achieved in phosphate glasses for only low concentrations of Cr3+ ions ( 0.07 wt.%) so that the efficiency of flashlamp-pumped erbium lasers could be improved by a factor of 1.5-4. The optimal conditions for achieving the best energy parameters of these lasers under free-lasing conditions were determined allowing for the spectral and energy distributions of the flashlamp radiation in the absorption range of the coactivator ions. By implementing these conditions using active elements 6 mm in diameter and 85 mm long, containing 17 wt.% Yb2O3, 0.25 wt.% Er2O3, and 0.07 wt.% Cr2O3, it was possible to achieve an efficiency of 1.2% for an electrical pump energy of 1 kJ. This was the highest efficiency achieved so far for erbium lasers. Measurements were made of the efficiency of transfer of the excitation energy from Cr3+ ions to Yb3+ ions at high levels of excitation of the medium.

Mechanism of the influence ofγradiation on the energy characteristics of YAG:Nd3+crystals

A study was made of a mechanism responsible for the deterioration of the energy characteristics of YAG:Nd3+ crystal lasers caused by the action of γ rays. The main cause of the reduction in the output energy of the laser as a result of γ irradiation was an increase in the short-lived losses at the wavelength of 1.06 μ, which appeared in the laser crystal under the action of the flashlamp radiation.

イオン打込み層のランプ・アニール

Recently, various transient annealing technologies have been intensively invesigated on activation of ionimplanted layers, using laser, electron beam, flash lamp, high-intensity arc-lamp, and solar radiation. But the application of these annealing technologies to device processing is still in its infancy.This paper describes an application of halogen lamp annealing to the activation of ion-implanted silicon and to CMOS LSI processing.The samples were heated with halogen lamps in nitrogen gas at an atmospheric pressure to 1200 °C for five seconds. This annealing activated the boron ions and phosphorus ions implanted layers and realized the same sheet resistivities as the furnace annealing (100 °C, 20 min.) with negligible dopant redistribution. 256 K CMOS ROM was fabricated using the halogen lamp annealing.The advantage of halogen lamp annealing technology was shown in place of furnace annealing without changing conventional processing steps.

Efficiency of excitation of POPOP vapor by wide-band flashlamp radiation

An experimental investigation was made of the fluorescence dynamics of 1, 4-di-[2-(5-p-phenyloxazolyl)] benzene (POPOP) at a CO2 buffer gas pressure of 0–1 MPa on exposure to wide-band excitation by flashlamp radiation with a flash duration of 250 nsec and a brightness temperature of 22 000 °K. It was found that the efficiency of population inversion by wide-band optical pumping, which is determined by the integral over the excitation spectrum of the dye, is 1.4 times lower for POPOP vapor stabilized with 1 MPa CO2 than for a POPOP solution in hexane. A dependence of the efficiency on the buffer gas pressure was determined. It was established that within the measurement error (~30%) the rate constant for singlet-triplet conversion of POPOP vapor, 4.5 × 107 sec−1, does not depend on the wavelength of the exciting radiation in the transmission band of quartz. The rate constant for photoconversion of POPOP vapor stabilized with 1 MPa CO2 is ~0.5 × 107 sec−1.

Interaction of high-power flashlamp radiation with an absorbing liquid

An experimental and theoretical investigation was made of the interaction of flashlamp radiation with an absorbing liquid. The experimental conditions corresponded to liquid cooling of flashlamps used for laser pumping. Such special effects in the liquid as a phase transition and a supercritical state were observed in the liquid. A method was developed for obtaining an analytic solution of the nonlinear optothermodynamic problem with an arbitrary equation of state of the liquid. The method was used to calculate the fields of thermodynamic variables in a liquid based on ethanol; an empirical enthalpy-pressure equation of state of ethanol was used in the calculations. A study was made of the mechanisms responsible for the heating of the liquid and the possibility of its boiling was considered allowing for the actual form of the curve bounding the phase volume of the system in the state diagram. The pressure developed in the liquid was measured by means of piezoelectric transducers, which were practically insensitive to the flashlamp radiation and were damped in respect of extraneous acoustic signals. The dependences of the pressure on the parameters of the problem were determined experimentally and found to be in agreement with the calculated curves.