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The paper describes a conception of controling the e lectrooptical laser Q-switch with high repetition rate. Construction and main electrical parameters of a driver are mentioned.
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Two systems for laser precision micrornachining and some results of their work. are presented in this paper. These systems were de signed and constructed in the Institute of Microelectronics and Optoelectronics of Warsaw University of Technology.
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The effects of an internal fieldlimiting aperture on the transversal mode distri bution and on the output beam characteristics are investigated theoretically for an unstable optical resonator of negativebranch configuration.
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The use of laser radiation for alloying the surface layer ot metals is one of the latest and fst—t1evelopirj methods for the laser treatment of surfaces. Layers of a different area of concentration of the alloying flldterial Cdfl b? abtained in the alloying process with a pulod laser. The paper presents the results of the studies on the effect of some factors upon basic parameters of the illoyed layers in molybdenum, tungsten and nickel.
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The paper presents the results of preliminary investigations of electronic system built using three krytrons. Results of applying this system to generation laser pulses by self -injection method are also presented.
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The cholesteric liquid crystal (CLC) layers show circular dichroism and thus they can be used in circular optical polarizers. The paper includes the analysis of conditions which the CLC material -for such a polarizer should fulfil. Cholesteric materials for circular polarizers of Nd glass laser radiation were selected. The dependence 0-F the CLC layers transmission on its temperature and thickness and on the radiation power density was investigated. Polarization properties of the CLC layers were investigated too. The optical quality of a model of liqud crystal polarizer was also researched.
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Numerical studies of the nonlinear operation of a fiber distributed feedback laser are presented. An approximate formula relating smallsignal gain to the output power and the parameters of the structure for this kind of lasers is derived. Characteristics revealing saturation effects for weak as well as strong coupling regions are presented for Nd:YAG fiber lasers. An optimal coupling strength providing maximum output power for given pumping rate of the laser medium is calculated.
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The pullpush effects in a distributed feedback laser are studied. An approximate formula for mode osillation above the threshold including finite linewidth of the active medium and the spatial hole burning effect is obtained. The laser characteristics as a function of the system parameters are obtained.
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The plane—parallel GaAs plate was applied as cw CO2 laser Q-switch modulator. The rotation of the plate with high angular speed gave the laser action which consisted of single pulses with the half-time width 0.5 is.
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We present the results of investigation of crystal growth optical and mechanical properties of optically uniaxial and piezoelectric crystals Owing to several advantages the crystals are well suited for practical application as laser active materials or high temperature piezoelectric sensors. I . I NT R 0 D U C T I 0 N During past few years a considerable progress has been made in the growing technique of single crystals of compounds with a general chemical formula ABC3O7 where A:Ba B:La Sm and C : Al Several compounds belonging to that large family were first obtained in the polycrystalline form y sintering the stoichiometric mixture of oxides at high temperature. 1 Preliminary x-ray investigation indicated that the crystals were of tetragonal symmetry space group P421m - D32d. Since all these compounds have identical structure and nearly the same unit cell parameters can expect that they will form solid solutions with a nonlimited or limited mutual solubility. In this paper we summarize the available information concernig the crystal growth and properties of two representatives of these compounds.
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The paper presents a laser system for investigations of pollution in the atmosphere using the differential absorption lidar (DIAL) technique. An idea of measurement of the NO2 902 and 03 contents in the air is described. A pumping laser which is underpressure N2 laser of 3 mJ in pulse energy and 20 Hz in repetition frequency is described in details. The principle of operation of the N2 laser dye laser system which enables the generation of two wavelengths simultaneously for determining of NO2 contents in the air is shown.
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The paper presents the description of a theoretical model construction selected calculation results and investigations of a lowpressure nitrogen laser pumped by a transverse electric discharge. A special theoretical model of the laser was followed by numerical calculations and then by the construction. The laser generates UV radiation pulses (X 3371nm) of energy to 2m3 and halfwidth to Gns. Maximum pulse repetition frequency was to 100Hz.
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A novel electro-optic configuration active modelocked laser oscillator is described. A regenerative amplifier system with an electrooptical shutter is used to the amplification of subnanosecond and nanosecond light pulses. k
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In this work a concept of twostate switch in which the phenomenon of the radiation power ''overflow'' from the zero order of diffraction to the higher orders occurring when the magnetic field normal to the layer changes was proposed. Also the idea of fivestate optical fiber switch based on magnetooptical modulator which plays a role of an op tical valve was introduced and discused.
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The secondorder statistical properties of the fully developed Gaussi an speck I e pattern generated by TEM1C mode have been consi dereci. The autocorrelation function of the complex speckle amplitude is calculated. The average visibility of interference fringes was measured and the experimental data are compared with the theoretical resul t.
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The paper presnts working conditions of an XCI excimer laser untypical gas mixture based on KrzXe instead of pure Xe. Such a choice was influenced by the necessity of Findin9 the way to replace imported and expensive Xe by gaseous components accesible in Poland. Determining the range of changes of laser extrnal parameters which enables its proper work with the new gas mixture was the aim of same investigations results of which are presented in this paper. The laser pulse output energy and the pulse duration as a Function of supply voltage and the mixture composition are presented. The range of proper conditions for the laser working with the new mixture He-Kr:Xe--HC1 was determined. The analysis of experimental results showed that using the new mixture ensures value of energy and pulse duration comparable with the ones obtained for the mixture He-''Xe--HCl. Spectral investigations showed the lack of influence of Kr presence in the mixture on the generation spectrum of the laser. L.
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This work is dedicated to the high-speed steel SW7M hardened with smelting by a laser. The study was carried out with the nonhardened and hardened specimens before laser treatment. As a result of smelting a grainy structure was obtained. On the boundries of grains a network of white phase is noticiable. Hardness of the nonhardened specimen becomes lesser with the distance from the elucidated surface. while in the hardened specimen at the depth of 600 900pm a hardness downfall below the value of the core.
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Metallographical (SEN and rnicrohardneas Investigations of M2 highspeed tool steel incited by a continuous CO2 laser are described. It was apparent that there has been considerable Influence of the graphite coating arid the scanning velocity on melted zone dimensions and its asresolidified structureS In comparison to the uncoated specimens laser melt ing of the specimens coated with a colloidal graphite layer resulted in the increased significantly dimensions of the laseraffected layer and coarser as resolidifled structure. Hardness of the melted zone in the uncoated samples was higher than that of both the graphite coated samples and the conventionally hardened matrix.
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The niatched filter has been developed historically as an one—dimensional detection filter for various communication systems1'2'3. It is the optimal filter for maximizing the signal-to-'noise ratio (SNR) . The concept of filtering in two dimensions has been introduced into two—dimensional linear systems as a simple extension of one-dimensional linear filter theory. Optical implementation of a matched filtering was a resuit of the development of the coherent light techniques and holography . In the past few years several correlation filters have been proposed. However, in many applications not only SNR, but also output peak sharpness, peak location, light efficiency, discriminability, and distortion invariance are very important filter parameters. A lot of problems related with optical pattern recognition may be reduced to detection and localization of search target. Various modifications of classical matched filtering are suggested in order to improve detection quality. All of them provide output peak sharpness minimalization. The sharper the correlation peak, the better location accuracy. Recently there are three basic realizations of the two dimensional correlation function in optics: - matched filtering including classical matched filtering (CMF), gradient filters (GF) , phase—only matched filtering (POF) , nonlinear matched filtering (NMF) , inverse filtering (IF) etc., - matched filtering with preprocessing, — joint transform correlator and its nonlinear version. In the present paper various modifications related to improvement of detection quality of the optical correlation methods mentioned above are presented and the output peak sharpness measured according to the peak-to--correlation energy (PCE) criterion is discussed.
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Using Ruby and Nd: glass lasers an influence of laser annealing on the dept.h distribution of Sb recoil at.oms in Si was studied. The recoil implant.at.ion of Sb at.oms in Si was carried out. in a Sb-Si bilayer system usini. 100keV Ar ions or 320keV Xe ions and doses ranging fom 5 x 10 i/cm2 to 5 x 1014i/cm2 • The depth distributions of Sb recoil at.oms were obtained from Rutherford backseat.taring spectra CRBS) measurements. The substitutional fraction of Sb at.oms was 0.35 0.55 in the case of laser annealed samples.
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The paper presents a brief description of a prototype of a XeC1 excimer laser for micraprocessing of materials. The planned main parameters of the laserare as follows: wavelength . . . . . . . . . . . . . . . . . . . . . . . . . 308 nm -''energyofapulse. . . . . . . . . . . . . lOOmJ -pulseduration (FWHM) . . . . . . . . . . . . . . . 2Ons repetition frequency . . . . . . . . . . . . . . 1O Hz peak power of a pulse . . . . . . . . . . . . . . . 5 MW With respect to currently carrried works with the prototype we show only preliminary results of testing of a laser head. The obtained maximum laser pulse energy exceeded 90 ml. However it should be pointed out that this value was obtained without any opt i mi z at i on of the 1 aser.
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This paper presents the results of investigations on the application of the well known Laser Flash Method for measuring thermal diffusivity of porous materials. The popularity of this method in materials engineering arise from its simplicity and other very well features. Simply model of porous body was applied for interpretation of thermal diffusivity changes caused by the variation of porosity humidity and sample''s effective temperature.
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The application of laser light containing several wavelengths can be advantageous in the determination of aerosol''s particles sizes with the method of light scattering because the accuracy of such measurements can be improved. The knowledge of size and concentration of aerosol particles present in the atmosphere is of great importance in many industrial technologies and also in basic researches. There are many methods of measurements of these parameters each characterized with certain advantages and disadvantages when considered from the point of view of the sampling process duration of the measurements measurements'' range and precision. It seems that one of the best methods of finding aerosol''s concentration and size distribution is based on the analysis of scattered light 2 The essence of this method is the measurement of power of light scattered into a definite sol id angle (Fig. 1 ). Lasers are most frequent ly used as 1 ight sources i 1 luminat ing aerosol '' s part ides3 . High intensity of 1 ight and the concentration in small volumes inherent in laser beams make it possible to extend the range of measurable sizes and concentrations of aerosol particles. direction of aerosol''s flow to . . laser beam 0 - :io e 0 . . . . . . scattered''*i light Fig. 1. The illustration of the principle of operation of the apparatus for the determination of particles'' sizes
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In this paper there are presented characteristic features (fine and coarse ring structures, depression and shoulder of profile shape) produced during laser pulse (ti = 7 ms) on melting surface of tin. Experimental and calculated data are discussed both in connection to transient capillary waves model and the model of convection driven by surface tension gradient.
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The paper presents investigations of the influence of parameters of the voltage pulse applied to the electrodes of electron gun on the current density spatial distribution of large aperture electron beam. It was shown that uniformity of current density distribution essentialy increases with the increase of steepness of the voltage pulse front and with the increase of the voltage amplitude.
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We report the first systematic measurements of the temperature dependence of optically induced birefringence in benzene 2bromo-- anisole 2-methoxybenzaldehyde and 4methoxybenzaldehyde. The optical Kerr constants relative to benzene are found to be: 1. 00 2. 45 5. 21 4. 89 and 4. 91. respectively. The refractive indices and densities of the liquids for the temperatures studied were also determined. From our measurements the molar Kerr constants and the effective molecular anisotropies were calculated as functions of temperature. The mean value of the secondorder optical hyperpolariZa bility have also been found. We draw some conclusions on the molecular interactions in the liquids. T If" LI I IJIJJJ Nonlinear optical effects in liquids are shaped not only by the optical properties of the isolated atoms (molecules) but moreover by their electric properties and mutual interactions. Hence optical birefringence induced by strong laser light also referred to as the Optical Kerr Effect (OEK) is a source of highly relevant information concerning the structure the electrical properties and the optical properties of atoms and molecules including their interactions in dense media. OKE measurements yield the optical Kerr constant which characterized the macroscopic properties of the medium. If carried out versus temperature OKE measurements additionally provide information on the local structure of the medium and 146 / SPIE Vol. 1391 Laser Technology Ill (1990) 0-8194-0458-6/91 /$4. 0
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There were carried out numerical investigations of the possibility of applying the self-injection technique for generation of short pulses jil rare-gas halide excimer lasers. We investigated a case in which the electrooptical switch is placed in a resonator and is contrulled by two half-wave voltage gates and active medium has the parameters typical for the KrF laser. The model regarded vibrational relaxation and collisional mixing of the B states of excimer molekule. The influence of parameters characterizing the course of voltage applied to the Q-switch upon energy power temporal shape and contrast of generated pulses was analysed. It was stated that there is a possibility of a controlled generation of pulses of time duration from a few hundreds of picoseconds to a few nanoseconds and power of on order higher than in case of free oscillation.
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There has been described the method of making use of the Doppler effect in laser anemometrics, indicating that in order to define the frequency shifting, the method of heterodyne action for light beams passing through the area of examined flow has been used. The optics /scheme/ of anemometer has been shown, pointing at the arrangement of interference striae as the place of measurement. The radiation e mitted from the place of measuring location is recorded by photode tector, and then in the photodetector signal one can separate the basic signal and the frequency signal /Doppler signal!. The recorded curves, correspoding to the basic and Doppler signals, are passed on to the analysing and calculating block which displays the value of the flow velocity.
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Optical Kerr effect investigations in liquid and gaseous carbon dioxide and the temperature dependence of this effect are reported. From our studies information concerning the molecular interactions and local structure of the medium were obtained. Using the method of indirect comparrison of the results of optical Kerr effect for liquids and gases it is found that the contribution to optical birefringence from a single CO2 molecule in gas and vapor phase is about 7 and 3. 5 times greater respectively than the contribution of the same molecule when in liquid phase. It is also shown that. the effective molecular anisotropy of the carbon dioxide molecule in the liquid phase is markedly lower than its value in the gas phase. This fact is interpreted as an effect of molecular interactions among CO2 molecules which are much stronger in the dense medium.
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During interaction with remote environments, the operator may benefit from the addition of force feedback to the ubiquitous visual feedback. However, the apparatus required for reactive force feedback (feedback which imposes the remote environment's motion-constraints on the user by applying joint torques) is cumbersome and expensive, especially when implemented in conjunction with high degree-offreedom precision joint motion sensing. Non-reactive, tactile feedback can provide similar information, and can be implemented at much lower cost. The purposes of this research were (1)todesign and demonstrate an inexpensive tactile feedback system, and (2) to determine the extent to which such a system could aid in the performance of a simple teleoperation task. After some experimentation with some different display technologies, and preliminary design, a vibrotactile display was chosen because of its low weight, size, and low cost. The final design consisted of two voice-coils, one each for the thumb and the index finger, which were driven by a 250 Hz variableamplitude signal produced by an analog electronics unit which was controlled by a PC. Experimental results are provided to show that the addition of the tactile display provides a small but significant improvement in manual tracking performance over the use of the visual display alone, and that the tracking task may be performed with only the tactile display. In further experiments the tactile display is compared with reactive force-feedback and is shown to confer most of the reactive display's performance improvement over tracking with only a visual display.
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Laser doping mechanism with the aid of the one pulse of the radiation has been described in this paper . Experiments have proved that mechan isin of the thennocapilary waves of melted metal is the fundamental effect influencing the final distrilution of dope in the dopir area.
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It is shown that b a certain changing of optical signals /irnages/ statisica1 properties there are possible the cases of nar rowing image elements /interference lines! width which are deterni ned by containing 99 percent of total signal power ai. d sirnu1ta neuously enlarging of the same element deterrnined b containing of 90 per-cent of total signal power. Sirniliar or opposite situations are called as contradictions /anbi noniies/ of energetic criteria for evaluation of image elements changes /spectra bands or interference lines!. any examples of apparent contradictions /antinoxnies! of energetic criteria for evaluation image elenients width changes for seven examined physically possible to obtain low-band power concentration radiant spectra are prsen ted. Range of usefulness of four other oflen used criteria for eva luation lines width changes was examined. 6 coefficients of bands width which are followed bi other numerous cases of wrong eva1ua tions of optical or optoelectronical s''stems " sharpening" images are given. 318 / SPIE Vol. 1391 Laser Technology 111(1990) O-8194-0458-6/91/$4. 0
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The effect of focus shift and its diameter changes due to high pump power level has been investigated theoretically in this paper. Two methods describing multi mode beam propagation have been developed and compared with the results of the experiment. The best coupling conditions of such laser beam with wave guide ( optical fiber) for a wide range of pump power have been discussed.
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A new method of Bessel beam generation by means of generation of special mode of electromagnetic field in confocal resonator with annular active medium is proposed. The estimations of sizes of " diffraction-free" zone are presented. A proposal is made to apply Bessel beam to accelerate a beam of charged particles
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Results of tuned Ti:sapphire laser investigations are presented in this paper. Shortening and stabi 1 i zat ion of pulse durat ion have been achieved us ing the SBS cell inside of the laser cavity. The main advantages of this laser and its features are shown. i:
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A positive branch unstable resonator for Nd:VAG oscillator producing a nearly gaussian beam in the far as well as in the near field was studied. The results of these studies are presented. Pulse duration from 5 to 20 ns were measured with energies up to 100 mJ and divergences less than 03 mrad The output characteristics of the oscillator for four geometrical magnifications of the pbranch unstable resonator were also reported
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An outputcoupler with radially variable reflectivity mirror (VRM) of a supergaussian profile obtained by thin film deposition technique on a glass substrate is presented. Application to a pulsed Nd:VAG laser with a confocal pbranch unstable resonator has produced diffraction limited output beams. Output characteristics of the osci I 1 ator Wi th prof i 1 ed and nonprof i I ed (uni form) outputcoup 1 ers and the same peak reflectivity were also compared.
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The transfer matrix method is employed to analyze the modal propagation within antiresonant reflecting optical waveguides (ARROW) implemented in InP/InGaAsP multilayer planar structures. The analysis provides an accurate picture of dispersion and attenuation of TE polarized waves at the operational wavelength of 1. 55 pm. The numerical results show the optimum values of system parameters for low loss operation and may be useful for designing various optoelectronic devices such as semiconductor lasers or optical amplifiers monolithically integrated with low loss passive ARROW guides which are suitable for coupling to external elements e. g. to optical fibers.
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In this paper a description of the construction and technology of manufacturing of ion argon laser with 1 m long metal-ceramic discharge tube is presented (The previous paper on the subject [2] has concerned discharge tube of the same kind but consisting of ten 10 cm long parts). There is also an analitical approach to the gas pumping effect in the paper.
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We''d like to present the use of krypton laser stimulation in the treatment of dry eye syndrom. 10 patients with dry eye syndrom were treated with irradiation of the lacrimal gland. Schirmer test and break up time were performed before and after therapy. After 10 days of treatment we observed higher value of secreted tear amount.
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The lasing properties of a new group of hemicyanine dyes in acetonitrile solution under the nitrogen laser excitation are pre sented.
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The paper outlines some design and operating characteristics of a 1. 5 kW carbon dioxide modular laser developed and built in IFFM for industrial applications.
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Nowadays PZT shifters are widely used for interferometric measurements by phase shifting methods. The required accuracy of single step is very high. There for the methods of measuring metrological features of PZT shifters are described specificly intensity methods in Michelson and Sagnac interferometers and Lissajoux figures method 1-D and 2-D Fourier transform method (FTM) in Fizeau interferometer. The 1-D FTM is found most convenient for real time calibration in experimental setup.
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In the paper is presented a numerical method for determining the thermal field in the material as well as the parameters characterizing the course of machining in conditions of surface vaporization under the impact of single pulses of laser radiation. There has been design. ed a computer program as well as computations were carried out for tungsten copper and titanium submitted to the impact of rectangular and Gaussian pulses. The following parameters have been determined as time functions: temperature distribution in the material shape and depth of the cra ter in formation rate of machining process efficiency energy enclosed in the material amount of energy required for removed material evaporation.
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The paper presents the possibility . of generation of the second harmonic pulse much shorter than the main pulse. The applied method enables for shaping the profile of both the second harmonic pulse and the pulse of basic frequency. The shaping is done by a nonlinear crtystal type II. The paper includes experimental results of generation of the second harmonic shortened pulse.
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Argon-dye laser photocoagulator for the microsurgery of the interior structure of the eye is described. Some technical specifications like power stability shape of the spots and the dependence of the power on the tissue vs. wavelenght for dye laser are given. Argon-dye photocoagulator was designed and constructed including argon laser tube and dye laser in Institute of Microelectronics and Optoelectronics Technical University of Warsaw.
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I n t he gi yen wor k photoel ec t r i c al and el ec t r ophys i c al pr oper t i es of the epitaxial films of Cd Hg Te have been measured before and x i-x after laser treatment. It has been shown that the resistance of the fi 1 m at the temper atur e T300 K has been i ncr eased by 3 fol d after exposing to several pulses of the laser . A rising of the resistance dun rig a 1 ong ti me after 1 aser treatment was al so noti ci abi e. As a resul t of gal vanomagneti c measurements taken yei1 ds that the concentr ati on of the i ntr i nsi c car r I er s had been i ncr eased from i5 -3 io -a 2. 6xl0 cm to 6x1 0 cm due to the 1 aser tr eatment . Fur ther the mobility of carriers decreased by about 100. According to the measurement of Hall coefficient in the region of impurity conduction at the temperature T K the hole concentrati on has become greater and the concentration of electrons has become lesser due to the laser treatment. Such changes of concentr ati on of el ectr ons coi nci de wi th the results of photoelectric measurements. Lifetime of
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The basic results of investigations of t he multikilowatt convective coexcitation 2 and power generation systems are described i n the paper The working ve medium medium was excited by a parameters , steady- state, and transverse DC time-dependent discharge. The laser beam characteristics and time variations of CO2 concentration have been determined basing on experimental investigat ion and complementary calculations. The paper contains also first approach towards problems connected to the laser output beam stabilization.
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Early stages of digital image processing reguire suitable application of the preprocessing operators. This paper concerns software tools developed to design the custom filters used on the initial processing stage in digital image analysis system. Subject terms: image processing convolution Laplacian of Gaussian median morphology.
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The work presents the results of the investigations of the interaction of pulsed laser light with matter. The effects of this interaction that is the changes of dielectric constant and refractive index lead in turn to the phenomenon of self focusing of light. Light pulses in the irradiated materials can generate mechanical vibrations what makes the material inhomogeneous and increases the scattering process. Self focusing of light can be applied for the modulation of the action of pulsed lasers. The losses for caused by the mechanical vibration in optical fibers can be determined as a ratio of scattered energy flux (Sr ) and the energy flux of the fundamental mode (So). The interaction of powerful beams of laser light with various media can result in the changes of their physical properties. Laser beams with suitable temporal and spatial characteristics generate mechanical vibrations in the irradiated media 1 . . The investigations on the dynamics of the phenomena accompanying the interaction of strong optical pulses with irradiated materials made it generally possible to find out the causes of the generation of mechanical vibrations during such interactions 1 2 6 7 Absorbing materials when subjected to the action of laser light quickly get hot and deformed and afterwards the generation of series of mechanical pulses into and out of the sample can occur. As a result of the impact of laser pulses onto
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This work reports the results of investigations of the dependence of the stability of the laser discharge and of the pulse energy on the repetition frequency of a TEA CO2 laser which was varied by changing the condenser charging voltage the condenser capacitance and the composition of the laser gas mixture (CO2:N2:He 1:l:XHe). It is shown that the pulse repetition frequency can be increased by Increasing the helium contents in the gas mixture and by decreasing the energy input into the discharge (or the energy stored in the capacitor). A design of a laser generating 2OmJ pulses at 20Hz without gas flow across the electrodes is described.
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The spatial techniques providing the robust technique for phase measurement are presented specifically the phase-stepped and Fourier transform methods. The grating phase-shifting approach is implemented into holographic speckle and moire interefrometry arrangements. The three-channel versions of these interferometers enable the measurements of dynamic events and in adverse conditions. For the technique where the fringes with carrier frequency are avaliable the refinements of Fourier transform method to facilitate measurements are presented. The advantages and disadvantages of these two spatial methods in comparison with temporal techniques are given.
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A low noise preamplifier for a photodiode detector of short laser pulses has been designed and constructed. The photodiode amplifier configuration has within the long wavelength bandwidth a NEP value of O. 64pWHf112. The dark output noise of the photodiode is 2. lnVHz112 the bandwidth is 6. 4MHz. An analysis of noise from different elements of the amplifier as well as a description of voltage and bandwidth optimization are presented.
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We present the results of theoretical analysis and of measurements of properties of both passive and active electronic components to be incorporated in a lownoise amplifier for use with a HgCdTe photodiode in a detector of weak 1O. 6im laser pulses. The effect of the working temperature of resistors and of capacitors on changes of their resistance and capacitance and on the noise level has been investigated and it is found that the most suitable types of these devices for cooled operation are metallized resistors and mica and styroflex capacitors. In selected applications monolithic ferroelectric capacitors may also be used. The noise and the amplifying properties of a broad range of bipolar MOSFET and JFET transistors were also measured and are compared graphically. On the basis of these results the JFET transistors are most suitable for low temperature use.
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The measurements of fluorescence and phosphorescence spectra of acidic ethanolic solutions of Rhodamine 110 Rhodamine 19 Rhodamine 6G Rhodamine B and Rhodamine 3B at temperature 77 K and 298 K were performed. Energies of the lowest triplet and singlet states were determined by the adjustment of analytical shape factors to experimental spectra.
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Delayed luminescence spectra of ethanolic solution of RhilO Rh19 Rh6G TmRh RhB and Rh3B at 77 K were investigated. Obtained results indicated that photoionization of the dye molecules being in their triplet states and then recombination of the pair ion electron is responsible for observed delayed fluorescence. Influence of excitation wavelength on the delayed luminescence spectra is presented.
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In studies of the laser light propagation in fog, cloud, rain, etc. as the start point is used to be Mie theory of single scattering. However, this theory fails under the conditions of low—visibility, because the process of scattering is strong and the probability of multiple scattering cannot be neglected. The task of this contribution is twofold: 1. To evaluate significance of the numerical error due to the neglecting of multiple scattering during of modelling of transmission function of dense aerodispersive system, 2. To find criteria for the specification of the parameters of laser beam, detection system, and aerodispersive screen, when this neglecting is acceptable.
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A model of the evolution of artificial fog based upon the solution of a general diffusion equation which describes classical diffusion due to Brownian motion as well as the effect of gravitational settling is obtained. The influence of these phenomena on the laser light transmission losses is presented.
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The results of analysis of optical pumping of a solid state laser with a high frequency train of pumping pulses are presented. In order to determine the effect of the various parameters of the pump on pumping effectiveness the population dynamics of the upper laser level were considered through application of a four level model of the active medium. Simple formulae have been derived for the maximum value of the initial gain coefficient attainable upon the nth pumping pulse. A comparison of the efficiency of pulsed pumping with that of continuous pumping is presented. Finally the results of measurements of pulsed laser diode arrays are reported.
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