Helium-neon Gas Laser Research Articles

EFFECTS OF PHOTOHEMOTHERAPY ON THE CLINICAL COURSE OF BRONCHIAL ASTHMA

Актуальность. Противовоспалительное и иммуномодулирующее действие фотогемотерапии подтверждено при миокардитах, хронической обструктивной болезни легких, ряде аутоиммунных и других заболеваний. Существуют единичные работы об использовании этого метода у больных бронхиальной астмой (БА). Цель – оценить влияние фотогемотерапии синим и красным светом на клиническое течение БА. Материал и методы. 480 больных, поступивших в стационар с легким (44,5%) и тяжелым (55,5%) обострением персистирующей БА средней тяжести, были рандомизированно распределены в опытную группу (n = 250), в которой наряду с традиционными методами лечения обострения БА использовали фотогемотерапию синим (n = 220) или красным (n = 30) светом, и в контрольную группу (n = 230), в которой пациенты получали стандартное лечение. Фотогемотерапия синим (cветодиодный аппарат Солярис) и красным (гелий-неоновый лазер) светом проводилась по следующей схеме: длительность процедуры – 30 минут, количество сеансов – от 5 до 7 через 2–3 дня. Результаты. У больных с обострением БА, леченных с использованием фотогемотерапии, по сравнению с пациентами, получавшими только стандартную терапию, происходила более быстрая выраженная положительная динамика клинических симптомов по общему астма-счету, достигавшая максимальных значений на 7–10-й день при легком обострении и на 10–14-й – при тяжелом. При этом терапевтический эффект в случае применения фотогемотерапии синим светом оказался выше, чем в группе больных, получавших лечение красным светом. Период трехлетнего наблюдения подтвердил эффективность фотогемотерапии в достижении контроля БА: полный контроль над заболеванием отмечался в 1,3 раза чаще, а количество госпитализаций в течение года было на 34,8% меньше, чем в группе получавших стандартную терапию. Заключение. Применение фотогемотерапии синим и красным светом имеет выраженное положительное влияние на клиническое течение БА, что проявляется ускорением наступления ремиссии, сокращением сроков и частоты госпитализации.

Design of an R.F. Excited Helium Neon Visible Gas Laser and Study of the Optimal Conditions for Gas Mixtures and Pressures

Design of a continuous were helium-neon visible gas laser has been described. Brewster angle window of fused quartz and external concave mirrors of B.S.C. glass have been used in the fabrication of resonant cavity. An RF oscillator having variable frequency in the range of 20-30 MHz and an out-put power of about 50 watts served as excitation source. Different mixture ratios of He and Ne have been tried and for each ratio power output was measured versus total pressure inside the discharge tube keeping cavity length constant. The optimum power output has been obtained for 5:1 mixture at 1.4 torr for a tube of length 55 cm and internal diameter 0.5 cm. Laser action at 1.53 meu has been achieved.`

Modeling of laser scanning system to determine its associated uncertainty of measurement

In the fabrication of fine wires such as filaments of lamps and optical fibers, it is always necessary to measure the diameter in real-time and correct the extrusion process. For metrological purposes, laser beam scanning technique will produce similar results as comparative to diffraction-assisted methods. A computerized laser beam scanning measurement system (LSM) is designed and fabricated. The LSM consists of a low power helium-neon gas laser source, a specially designed collimating lens, a hysteresis synchronous motor, a photo detector and a protective replaceable window along with temperature sensor. The LSM is mathematically modeled to identify various error contributing sources. The LSM is calibrated using a set of national reference standard cylindrical pins and a set of national reference standard slots to determine its relative calibration factor. The uncertainty of measurement achieved in the range of (0–35) mm is ± (0.55 +39.2L/m) µm.

Determination of blood glucose concentration by back propagation neural network

This paper presents a supervised backpropagation neural (BPN) network for the determination of blood glucose in diabetic patients. Non- invasive measurement of blood glucose concentration based on reflected laser beam from the index finger has been reported in this paper. This method depends on Helium-Neon (He-Ne) gas laser operating at 632.8 nm wave length. During measurement the index finger is placed in the laser beam transceiver unit, the reflected optical signal is converted into its corresponding electrical signal and the obtained signal is processed by the neural network which presents the results in the form of blood glucose concentration. Diabetes database used for empirical comparisons and the results are shown that BPN network performs better. Keywords: Artificial neural network, diabetes mellitus, non-invasive measurement, supervised learning.

Determination of blood glucose concentration by back propagation neural network

This paper presents a supervised backpropagation neural (BPN) network for the determination of blood glucose in diabetic patients. Non- invasive measurement of blood glucose concentration based on reflected laser beam from the index finger has been reported in this paper. This method depends on Helium-Neon (He-Ne) gas laser operating at 632.8 nm wave length. During measurement the index finger is placed in the laser beam transceiver unit, the reflected optical signal is converted into its corresponding electrical signal and the obtained signal is processed by the neural network which presents the results in the form of blood glucose concentration. Diabetes database used for empirical comparisons and the results are shown that BPN network performs better.

Killing of the Yeast and Hyphal Forms of Candida albicans Using a Light-Activated Antimicrobial Agent

Oral infections due to Candida albicans are a common occurrence in patients with acquired immunodeficiency syndrome (AIDS). The purpose of this investigation was to determine whether the yeast and hyphal forms of the organism could be killed using the light-activated antimicrobial agent toluidine blue O (TBO). Three variables were investigated: TBO concentration, laser light dose and pre-irradiation time (PIT). Irradiation with light from a helium neon (HeNe) gas laser used in conjunction with the photosensitiser TBO resulted in substantial kills of both the yeast and hyphal forms. Killing was light dose-dependent with 42 J being the most effective dose. The optimum PIT for the yeast form was 5 min, whereas killing of the hyphal form was not affected by PIT. The results of this study have shown that both forms of C. albicans are susceptible to lethal photosensitisation using TBO in conjunction with HeNe laser light, suggesting the possibility that this approach could be useful for eliminating the organism from diseased lesions in vivo.

Near-Threshold Fatigue Crack Growth Behavior of SUS304 Steel at High Temperatures Using Interferometric Strain/Displacement Gage. 1st Report, Crack Closure Behavior.

Interferometric strain-displacement gauge(I.S.D.G.) testing system was developed for the measurement of the crack opening displacement at high temperatures. Helium-Neon gas laser and center-cracked specimens of type SUS304 austenitic stainless steel were used. Fatigue crack growth tests were conducted at 450, 550, 650 and 700°C at stress ratios of R=-0.1 and 0.5. Using I.S.D.G.for the measurement of crack closure modified using platinum plate and optical filter, crack opening displacement was found to be measured with good accuracy at all temperatures tested. Results showed that crack closure was observed at R=-0.1, while no crack closure was observed at R=0.5 even at 650°C. From the results of the measurement of fatigue crack closure in the near-threshold regime at all temperatures investigated, it was found that rapid increase and decrease in crack growth rate da/dN were observed when crack opening ratio U showed rapid increase and decrease, respectively.

Lifetimes of cold cathodes for helium-neon gas lasers

The energy distribution of ions, which are incident on the cathode of a glow discharge, is used to derive an expression for the rate of sputtering of a cold cathode as a function of the discharge parameters. The calculated rate of sputtering is compared with measured helium-neon cathode longevity as a function of discharge current density and fillgas pressure, and a model for helium-neon cathode mortality is developed. This theory is used to estimate the expected longevity of laser cathodes made from different materials.

Application of laser holographic techniques to investigate crustal deformations

Laser holographic techniques can be used to detect small deformations of three-dimensional objects, of the order of the wavelength of the laser light. We report the use of laser holography to measure the crustal deformation in a deep tunnel at Amagase, Kyoto, Japan. A recording system consisting of a helium–neon gas laser and associated optical elements was installed in the observation tunnel in 1984. Using this sytem, holograms of a section of the tunnel wall ∼2m in diameter are directly recorded on photographic plates. When the reconstructed image of a hologram is superposed on the current (‘real-time’) image of the tunnel wall, many interference fringes can be seen through the developed photographic plate. The fringe displacement, formed by the deformation of the tunnel, is continuously monitored with a video camera and a video-cassette recorder. The measured fringe displacement in the interference pattern is consistent with strain changes obtained from extensometers which have been installed in the same tunnel.

Tooth position measurements on dental casts using holographic images

A new accurate method for comparing tooth positions on dental casts at different stages is described. Holograms of casts were prepared with a helium-neon gas laser. For evaluation of tooth movements, a cast and hologram representing different time points were superimposed by means of an adjustable x-y stage. Occlusal surface detail was used as a reference for the superimposition. Positional changes of the upper incisors were detected as discrepancies between the cast and the hologram image.

Exploring Laser Light: Laboratory Exercises and Lecture Demonstrations Performed with Low-Power Helium-Neon Gas Lasers

Exploring Laser Light: Laboratory Exercises and Lecture Demonstrations Performed with Low-Power Helium-Neon Gas Lasers

Laser-induced chemical processes

Proposals for controlling or inducing chemical reactions with laser light have been around almost as long as lasers themselves. Immediately after Theodore Maiman's invention of the ruby laser in 1960 and Ali Javan, William Bennett and Donald Herriott's invention of the helium–neon gas laser in 1961 suggestions for using this new type of light source in chemical processes followed. The proposals resulted essentially from adapting already well-known principles of photochemistry. Yet almost no research employing lasers in chemistry was done for ten years. Not until tunable lasers and high-powered infrared lasers arrived at the end of the 1960's and in the early 1970's did laser chemistry become experimentally feasible, and the period since then has seen intense and systematic study of atomic and molecular processes. Of particular interest are those selective processes applicable to laser isotope separation, such as the work on carbon isotopes carried out in the apparatus shown in figure 1 and discussed later in this article. Selective processes also appear to be useful for the production of highly pure substances and for the study of certain photobiochemical compounds. In this article I will be able to give only a brief survey of the great amount of work currently in progress, concentrating particularly on those aspects being studied at laboratories in the Soviet Union.

1] Pulsed laser interferometry in the ultracentrifuge

This chapter presents two experimental arrangements to describe the role of pulsed laser light in the ultracentrifuge: one arrangement employs a pulsed argon ion laser of moderately high intensity, while the other modulates a low power helium–neon gas laser either externally with a Pockel cell or by means of internal switching. Both arrangements make possible the illumination of (tangentially) selected regions of the rotor and cells. The Pockel cell modulation system makes possible finer control of the region to be illuminated because of its shorter pulse length, down to 0.8 μsec compared to the ∼6 μsec for the unmodified pulsed argon ion laser. The argon ion laser emits significantly higher light intensity than the He–Ne lasers used and, in addition, can provide a number of laser lines in the green and blue region of the spectrum. The pulsed argon ion laser system is also described in the chapter. Studies show that the pulsed argon ion laser is promising as a light source for real-time data acquisition with the Rayleigh optics.

Simultaneous Recording of Electroretinogram and Visual Evoked Response

A system has been tested that allows simultaneous recording of the retinal response (electroretinogram [ERG]) and the occipital response (visual evoked response [VER]) with focal photic stimulation of the retina under direct observation of the fundus. A helium-neon gas laser is used as a stimulus source. The laser is chopped either by a pen motor or a rotating disc. The laser is attached to a biomicroscope through which the examiner can observe the fundus of the subject during the entire recording session. The optically clear contact lens is made with a flat surface that neutralizes refraction due to the cornea, thereby allowing fundus observation by microscope. Two metal wires mounted inside and outside of the lens serve as the electrode for the ERG. Graticules consisting of concentric circles and radial lines are projected onto the subject's fundus, providing a pattern that the examiner can use to determine the exact location to be stimulated in the fundus. With proper adjustment of stimulus and background illumination, local ERG and VER can be recorded simultaneously by stimulating the macula.

Laser-light-transmittance and the aerosols above the sea surface

The light transmittance was empirically examined by using the beam of helium-neon gas laser (λ=0.6328 μ) propagated above the sea surface (1.6 m height). Simultaneous measurements were made on the relative humidity and the air temperature together with samplings of all the aerosols.

Preparation and thermomagnetic properties of Ti-doped MnBi thin films

Ti-substituted MnBi thin films have been prepared on glass substrates by a vacuum deposition technique, and studies of magnetic, magnetooptic, and thermomagnetic properties of the films have been made. The nominal composition range of Mn 1-x Ti x Bi was x=0.1 to 0.4. The films were well oriented with the c-axis perpendicular to the film plane. The Curie point of the quenched high temperature phase (qhtp) decreased with increasing Ti-concentration, but that of the low temperature phase (ltp) was not altered by Ti-doping. The best Kerr rotation obtained for the qhtp films with x=0.4 was 0.5 deg at 6328 A. Both the Faraday and the Kerr rotation of the ltp and qhtp films decreased with increasing the Ti concentration. The time constant associated with the qhtp to ltp transformation was 103sec at 180°C for x=0.4. Curie point writing experiments with a helium-neon gas laser showed that the writing threshold of the qhtp film was about one third of that of the ltp film.

A Laser Photoelectric Colorimeter

Abstract A colorimeter was fabricated from a helium-neon gas laser and a detector from an available spectrophotometer. The intensity and coherence of the laser light source permitted measuring a wide range of absorbances with monochromatic light. Neutral density filters were used to regulate the light intensity.

Interaction between collinear asymmetric cracks

Thin strips made of perspex and containing two collinear internal cracks of different length were subjected to tension. The thickness variation of the strips was depicted by the reflected-shadow method, in which a coherent monochromatic light beam, emitted from a helium-neon gas laser, was partly reflected from the rear surface of the specimen. The light rays emerging from the plate, which were twice refracted along the thickness and reflected on the rear surface of the plate, were retarded according to Favre's and Neumann's law. The retarded light rays were focused on a caustic surface which depicted the boundary between the constrained area surrounding the crack tip and the remainder of the plate. In this paper two asymmetric collinear internal cracks of different lengths were studied and the interaction between these cracks was evaluated by measuring the variation of the diameter and the distortion of the shape of the caustics for various ratios of crack lengths.

A laser interferometric differential refractometer for detection of chromatographic effluent and measurement of volume elasticity of liquids

A recording liquid interferometer with a sensing volume of only 4 mu l and a lower detection limit of refractive index of less than 2*10-7 has been developed using the narrow beam of a small helium-neon gas laser. The instrument was originally designed for the detection of liquid chromatographic effluents in small-diameter packed capillary columns. It is suitable for use at high liquid pressures (e.g. 50 kg cm-2), as in the study of volume elasticity, and probably also as a detector in supercritical fluid-phase chromatography, using a separation technique recently developed in our laboratory. A special and more versatile phase-to-voltage converter was devised to record the optical phase shift in the interferometer. The instrument and some experimental results obtained with it are described.

Method of quick detection of antigen-antibody precipitin reaction.

A quick qualitative technique was developed for detection of the soluble antigen (Ag) and antibody (Ab) complex formed as the result of union between Ag and Ab from solution. A drop 05 each sample is placed on a microscope slide coated with silver; the nonmetalized side of the slide is resting on the microscope stage. The other slide is positioned very gently in place to form a wedge, and an interferometric fringe is formed by using a low-power helium-neon gas laser (6328 A) as monochromatic light source. If Ag and Ab are specific, the precipate complex and its growth can be observed within five minutes. The short time requirement is an advantage over other immunodiffusion methods.