Investigations on soft x-ray and extreme ultraviolet (EUV) emissions from a gas puff target irradiated with high-power laser pulses are presented. The aim of the studies is to develop efficient and debris-free laser plasma x-ray and EUV sources for applications in microscopy, lithography and microtechnology. Recent studies on soft x-ray and EUV lasers generated using an elongated gas puff target irradiated with picosecond pulses are presented as well.

Recent enormous progress in the technology of ultrashort-pulse lasers has resulted in the generation of extremely high light intensities approacing 10²¹ W/cm². Even at a hundred times lower intensity, electrons oscillate in the laser field with velocities close to the velocity of light and the interaction of laser light with matter is relativistic. The great non-linear forces produced by a laser pulse duing the interaction can be used to accelerate electrons and ions to energies of megaelectronvolts in distances of only microns. This creates a prospect for the construction of compact laser-based particle accelerators and their unique applications in material science, medicine and nuclear physics on a tabletop. In this paper recent achievements in the laser-based acceleration of electrons, protons and heavy ions are briefly reviewed. Some results obtained in this fascinating field in Poland are presented.

Cooling and trapping neural atoms with laser beams became a standard method of studying atom properties in temperatures close to absolute zero. Precise knowledge of physical parameters of the atomic sample is of prime importance in such studies, particularly the knowledge of the number of trapped atoms, their density and temperature. Diagnostics aiming at determination of these parameters has to be performed optically, mainly with the spectroscopic methods. In this paper, we present basic principles of obtaining ultra-cold atoms and methods used for their diagnostics. Some examples of quantum effects specific for low-temperatures, revealed by these methods, are also demonstrated.

The Rayleight scattering spectra of polyethyleneglycols with different average molecular weight are presented. In the study we used the compounds with average molecular weight 1500 and 2000. The temperature and concentration dependencies of the Rayleigh scattering spectra have given the possibility to determine Rayleigh parameters, also isotropy and anisotropy scattering molecular factors.

Laser-induced fluorescence (LIF) technique aided by intensified CCD light signal detection and fast digital image processing is demonstrated to be a useful diagnostic method for in-situ observation of the discharge-induced plasma-chemistry processes responsible for NO_x(NO + NO₂) decomposition occurring in non-thermal plasma reactors. In this paper a method and results of the LIF measurement of two-dimensional distribution of the ground-state NO molecule density inside a DC positive streamer corona reactor during NO removal from a flue gas simulator [air/NO(up to 300 ppm)] are presented. Either a needle-to-plate or nozzle-to-plate electrode system, having an electrode gap of 30-50 mm was used for generating the corona discharge in the reactor. The LIF monitoring of NO molecules was carried out under the steady-state DC corona discharge condition. The laser-induced fluorescence on the transition NO X²Π(v"=0)←A²Σ⁺(v'=0) at λ=226nm was chosen for monitoring ground-state NO molecules in the reactor. This transition was induced by irradiation of the NO molecules with UV laser pulses generated by a laser system consisted of a XeF excimer laser, dye laser and BBO crystal. The laser pulses from the XeF excimer laser (Lambda Physik, Complex 150, λ=351 nm) pumped the dye laser (Lambda Physik, Scanmate) with Coumarin 47 as a dye, which generated the laser beam of a wavelength turned around λ=450 nm. Then, the tuned dye laser beam pumped the BBO crystal in which the second harmonic radiation of a wavelength correspondingly tuned around λ=226 nm was generated. The 226-nm UV laser pulses of energy of 0.8-2 mJ and duration of about 20 ns were transformed into the form of the so-called laser sheet (width of 1 mm, height of 30-50 mm) which passed between the electrodes through the operating gas. The obtained results, presented in the form of images, which illustrated the two-dimensional distributions of NO molecule concentration in the non-thermal reactor, showed that the corona discharge-induced removal of NO molecules occurred not only in the vicinity of the plasma region formed by the corona discharge-induced removal of NO molecules occurred not only in the vicinity of the plasma region formed by the corona streamers and in the downstream region of the reactor but also in the upstream region of the reactor, i.e. before the flue gas simulator has entered the plasma region. This information obtained owing to the LIF technique, is important for the understanding of the plasma-chemistry processes responsible for NO_x decomposition in non-thermal plasma reactors and for optimising their performance.

Temperature dependence of Brillouin light scattering in selected dimethacrylates has been studied. For the compounds studied, being multifunctional monomers, the values of hypersound speed have been determined. It has been established that with increasing temperature the hypersound speed decreases for all substances studied.

The Raman scattering spectra of polyethyleneglycols with different mean molecular weight have been obtained vs. concentration and temperature. The measurements were performed for compounds of mean molecular weight 1500 and 2000. On the basis of the characteristic frequency data of atomic group vibration in organic compounds, the bands observed in Raman spectra have been assigned. The temperature ranges of the phase transition and the change in the order parameters have been estimated from the temperature dependence of the phonon band parameters of the polymers studied. Moreover, the shape of the O - H band vs. polymer concentration has been examined.

A prototype of multiwavelength lidar system for investigation of atmospheric aerosol particles distribution is presented. This technique consists on relation between of the cross section for the light scattering and the particle size as well as the scattered radiation wavelength. Our lidar working simultaneously on several wavelengths is based on the system with a Ti:Sa laser, generating the light pulses at λ=850 and λ=750 nm, which are also frequency doubled and tripled. Additionally a Nd:YAG laser, working on the fundamental and on its second harmonics (λ=1064 and λ=532 nm), is also used. Special algorithms for retrieving the aerosol particles size distribution from the lidar signals were elaborated. The system was applied during a field campaign in Karkonosze Mountains.

This paper presents results of a study of aerosol pollution distribution and dynamics measured by lidar observations over the city of Athens. The seasonal dynamics of vertical changes in the backscattering coefficient, extinction coefficient and lidar ratio for lower troposphere has been determined.

Both marine and urban aerosols, which differ in their origin and chemical composition, are subjected to strong dynamic processes in the coastal areas, especially over strongly urbanised areas. The simultanteous presence of both types of aerosols leads to their effective mixing due to the action of winds and convection. This work presents examples of interactions of the two types of aerosols and the impact of the dynamic atmospheric processes on migration of aerosol masses, at two locations in Athens and Kolobrzeg.

The iterative (with constant "lidar ratio") and the general recursive (with variable "lidar ratio") algorithms have been used to backscattering lidar data. The data have been collected in the Lidar Center in Thessalonica, Greece. The vertical profiles of backscatter coefficient retrieved with these two algorithms differ slightly. The vertical profile of "lidar ratio" for the laser wavelength 532 nm, depending on the day or time of the day, changes its values but doesn't reveal any essential structure. The wavelength 355 nm seems to be more "sensitive" and shows some structure for "lidar ratio". Most probably these structures are due to the presence of different aerosol layers. From vertical backscatter coefficients, both 355 nm and 532 nm, at least, two aerosol layers can be differentiated.

Vertical profiles of aerosol extinction and "lidar ratios" of the lower troposphere in Thessalonica have been measured with two -wavelengths lidar. The extinction profile for the wavelength 355 nm seem to be insensitive for the time of the day. The profile for 532 nm has its maximum intensity at about 7 am, then decreases and increases during the afternoon and the evening. The vertical profiles of "lidar ratio" are structured for 355 nm but for 532 nm, are almost constant. It has been concluded that, at least, two different kinds of aerosols contribute to the observed profiles: one sensitive (532 nm) and a second one, insensitive for the changes in solar radiation (355 nm) during the day. Both, extinction and "lidar ratios" are characterized by high values for the wavelength 355 nm.

The paper discusses the applications of optical coherence tomography (OCT) in the diagnosis of eye disorders, i.e. OCT of the posterior segment of the eyeball and conditions that must be met to use OCT in the studies of the anterior chamber. Limitations of the technique and clinical requirements it must satisfy are also described.

Ninety-eight patients were included in clinical trials. They were divided into 3 groups, depending on the severity of lower lid inversion. Eighteen patients were included in the group with mild lid inversion; 59 patients had moderate lid inversion and in 21 patients the inversion was severe. Additionally, the patients were subdivided into two groups, according to their age - up to and above the age of 69 years. In both age groups, patients with moderate entropion predominated. All patients underwent photocoagulation of the lower lid. Post-operative wound healing took about 14 days. The effect was described as good when the position of the lid returned to normal with the lashes at an angle of about 45° to the free edge of the eyelid. When the position of the eyelid was normal with the lashes at an angle of about 60° or more to the edge of the lid and not rubbing against the globe, the effect was considered satisfactory. When the inversion of the lid was not corrected, the effect was unsatisfactory. Good effects were seen in 61% of patients, 21% of the patients demonstrated satisfactory effects and in 18% the outcome was unsatisfactory. The best results were observed in patients with mild entropion, aged 69 years and younger.

Each year an increasing amount of research is published on the use of photodynamic therapy in medicine. The most recent research has focused mostly on the use of photosensitizer called vertoporphyrin (Visudyne) is the treatment of subretinal neovascularization in age-related macular degeneration (AMD) or myopia, following a substantial amount of ophthalmology research mostly experimental on the application of the method in diagnosis and treatment of some eye tumors. In the Department of Ophthalmology of Polish Medical University in Warsaw, PDT was used as supplementary method in a selected group of patients with chronic virus ulcer of the cornea and keratopathies. During the treatment 5-aminolevulinic acid (5-ALA) was applied in ointment form as a photosensitizer activated with light wave of 633 nm. It appears, on the basis of the results obtained, that photodynamic therapy (ALA-PDT) may become in the future a valuable supplement to the methods being used at the present treating pathological states of the cornea.

The authors present their many years of experience in the area of laryngological surgery with various types of solid lasers. In our clinical practice we use Nd-YAG, Ho-YAG and Er-YAG surgical lasers. There are many reasons for applying lasers, depending on medical conditions. One of the most frequent cases are the nasal polyps, where surgical treatment is aimed at curing the results. For this type the procedures there was applied Nd-YAG laser, which has shortened the period of treatment and extended the remission. We also use this laser for mucal tissue corrections of the nasal conchs through deep coagulation effect. The above mentioned laser is also useful for the preventative treatment of granulation stenosis by removal of granulation tissue from different sections of the upper way; from the nose to the trachea.Other laser procedures in the nasal area include coagulation of Kisselbach locus, bleeding in Rendu-Osler disease, separating adhesions of the nasal concha from the nasal septum, coagulation of septal bleeding polyps, angiomas of different location, small papillomae of throat and nose, and reduction of hypertrophy nasopharyngeal mucoosa in OSAS patients, and uvolo-palato-pharyngoplasty (UPPP). Neodymium laser is also used for the management of neoplastic diseases in palliative and radical (CA. basocellulare) treatment for the resection of the premalignant changes (papilloma, leukoplakia) and early neoplastic changes of throat and larynx. Keloplasty in the area of larynx and trachea is performed with the use of Ho-YAG laser, with shallow effect, regardless of the density of tissue, enabling coagulation of vascular vessels. It enables non-traumatic resections of bone structures, such as the wall of maxillary sinus, nasal spine, or conchoplasty; the mucal tissue and the frame. Recent clinical tests are examining the possibilities of Er-YAG laser application for crushing calculus in the salivary ducts. Using lasers in laryngology enables their extensive application, and in many cases, as a method of treatment, it is superior effect wise to traditional methods. Laser beams are applied via special routes, which facilitates their adequate utilization.

Observation and selective destruction of biological tissues, due to use of photochemical reaction sensitised with photosensitive dyes, are applied in modern method of tumor diagnosis and treatment as well as destruction of atheromatous plaques and restenosis prevention. This method, called photodynamic method (PDT), has been developed for recent 30 years in USA, Canada, Japan, and China and in majority of European countries. It has many advantages that distinguish it from among other currently used diagnostic and therapeutic methods. Both, the applied photosensitizers and photodynamic effect influence on active biological compounds present in an organism, mainly on enzymatic proteins, hormones, and particular elements of immunological system. The PDT method can be used not only for in situ tumor treatment but also for the treatment in metastasis state. It was thought previously that direct activity of cytotoxic radicals and singlet oxygen causes tissues necrosis. At present, additional investigations are performed on destruction mechanisms, i.e., occlusion of blood vessels and lymphatic vessels and PDT influence on immunological system revealing in cytokines release. In Poland, the technology of new class of photosensitizer - diaminoacid derivatives of protoporphyrin PP(AA)₂Arg₂ as well as the basic half-product - hemis of very high purity has been developed and activities for their industrial production have been performed. In vitro investigations on quantum luminescence yield and singlet oxygen quantum yield of the obtained preparations were made. These compounds do not show toxic properties and they are neither mutagenic nor teratogenic. Three aminoacid protoporphyrine derivatives were chosen for industrial scale production, i.e., PP(Ala)₂Arg₂, PP(Ser)₂Arg₂, PP(Plu)₂Arg₂ that were efficient for the largest number of tumors investigated on cell lines. A preparation being the mixture of these derivatives is called Sensyphyrine. In the first stage of Sensyphyrine examinations in surgery, otolaryngology, and teracosurgery clinics over 100 patients were investigated. During the years 1999-2001, the technologies of Polish photosensitizer and dermatological preparation have been developed. This photosensitizer - IX(PPIX) protoporphyrine is 5-aminoavulenic acid (ALA) of pharmaceutic purity (99.5%) and the final form of dermatological preparation is in form of a cream (FOTOACID). The obtained preparation and designed diagnostic systems and therapeutic sources enabled us to carry out initial investigations on animals and next clinical in 400 patients.

The authors discuss the results, obtained so far during three years' clinical examination, of laser therapy in the treatment of patients suffering from multiple sclerosis. They regard both the results of former laboratory experiments and so far discovered mechanisms of biological influence of laser light as an objective explanation of high effectiveness of laser therapy in the csae of this so far incurable disease. They discuss wide range of biological mechanisms of laser therapy, examined so far on different levels (cell, tissue, organ), allowing the explanation of beneficial influence of laser light in pathogenetically different morbidities.

This paper presents laser-induced fluroescence method (LIF) employing endogenous ("autofluroescence") and exogenous fluorophores. LIF is applied for clinical diagnosis in dermatology, gynaecology, urology, lung tumors as well as for early dentin caries. We describe the analysers with He-Ne, He-Cd, and SHG Nd:YAG lasers and new generation systems based on blue semiconductor GaN lasers that have been implemented into clinical practice till now. The LIF method, fundamental one for many medical applications, with excitation radiation of wavelength 400 nm could be appl,ied only using tunable dye lasers or titanium lasers adequte for laboratory investigations. Development of GaN laser shows possibility to design portable, compact diagnostic devices as multi-channel analysers of fluorescence spectra and surface imaging devoted to clinical application. The designed systems used for spectra measurement and registration of fluorescence images include lasers of power 5-30 mW and generate wavelengths of 405-407 nm. They are widely used in PDT method for investigation of superficial distribution of accumulation kinetics of all known photosensitizers, their elimination, and degradation as well as for treatment of superficial lesions of mucosa and skin. Excitation of exogenous porphrins in Soret band makes possible to estimate their concentration and a period of healthy skin photosensitivity that occurs after photosensitiser injections. Due to high sensitivity of spectrum analysers, properties of photosensitisers can be investigated in vitro (e.g. their aggregation, purity, chromatographic distributions) when their concentrations are 2-3 times lower in comparison to concentrations investigated with typical spectrofluorescence methods. Dentistry diagnosis is a new field in which GaN laser devices can be applied. After induction with blue light, decreased autofluorescence intensity can be observed when dentin caries occur and strong characteristic bands of endogenous porphyrines when parodentosis or dental plaque are present.

Development of Polycrystalline Infrared (PIR-) fibers extruded from solid solutions of AgCl/AgBr has opened a new horizon of molecular spectroscopy applications in 4-18 micron range of spectra. PIR-fiber cables and probes could be coupled with a variety of Fourier Transform Infrared (FTIR) spectrometer and Tunable Diode Lasers (TDL), including pig tailing of Mercury Cadmium Tellurium (MCT) detectors. Using these techniques no sample preparation is necessary for PIR-fiber probes have been used to measure reflection and absorption spectra, in situ, in vivo, in real time and even multiplexed. Such PIR-fiber probes have been used for evanescent absorption spectroscopy of malignant tissue and skin surface diagnostics in-vivo, glucose detection in blood as well as crude oil composition analysis, for organic pollution and nuclear waste monitoring. A review of various PIR-fiber applications in medicine, industry and environment control is presented. The synergy of PIR-fibers flexibility with a super high spectral resolution of TDL spectrometers with Δv=10^-4cm^-1, provides the unique tool for gas analysis, specifically wiht PIR-fibers are coupled as pigtails with MCT-detectors and Pb-salt lasers. Design of multichannel PIR-fiber tailed TDL spectrometer could be used as a portable device for multispectral gas analysis as 1 ppb level of detectivity for various applications in medicine and biotechnology.

The main aim of the presented experiments was to assess in vitro capabilities of Photosensitizer Assisted Light Induced Fluorescence (PALIF) to recognise different stages of atherosclerosis. Mono-L-asparyl-chlorin e-6 was used as a photosensitising agent and ultraviolet light (440 nm) as an excitation source to obtain spectra map of artery wall. The luminescence spectra were collected and analised. The specimans were histologically examined and classified into three groups: normal artery wall, atherosclerotic noncalcified plaque and calcified plaque. The ratio of green fluorescence (coming from collagen) to red fluorescence (coming from chlorin e6 bonded with lipid reach, noncalcified tissue) gies a chance to distinguish between normal artery or calcified plaque and noncalcified, lipid reach plaque. Further trials must be performed to evaluate in vitro athermoa detection algorithm as a feedback system for photoangioplasty.

The study compares the results of classical surgical treatment with laserotherapy in lithiasis of submandibular salivary glands. The study included 48 patients, 26 of which were treated with application of a CO₂ laser. The follow-up did not reveal any postoperative complications in the course of healing. No relapse of the disease was observed in patients.

Biostimulative laser therapy was used in 4 patients with actinomycosis. In each patient extraoral radiation by means of the "contact point" method was applied. The results were evaluated on the basis of clinical and bacteriological examinations. Laserotherapy had a beneficial effect on the course of treatment of actinomycosis and shortened the time of curing.

The aim of our study was to evaluate treatment of changes on male sex organs with CO₂ and Nd:YAG lasers. Material consisted of 34 male patients of Diagnostic and Observational Department of Gynecologic and Obstetrical University Hospital in Poznan, Poland treated between 1998 and 2002. Results of treatment with both lasers were similar when comparing therapeutic effect and side effects. No complication was noticed and the observed differences were not statistically significant.

The subject of the study was transportation of glucose molecules through a cuprophase membrane by the earlier devised method based on the phenomenon of light interference sensitive to changes in the optical density in two neighbouring chambers separated by a membrane. In the experiment the number of light and dark interference fringes and the rate of their movement through the observation slit were recorded. The analysis of time changes in the concentration of the solutions in the two chambers brings information on the dynamics and mechanism of glucose molecules transportation through the membrane.

There are several methods of treating cervical dysplasia, including surgical and electric conisation, laservaporisation. The aim of our study was to evaluate leep-loop method and laservaporisation wtih CO₂ laser. Material consisted of 49 women, 28 underwent leep-loop conisation and 21 lavervaporisation. The effectiveness of laser treatment was 90,4% and with leep-loop 96,4%, but the difference was not statistically significant. Mean time of wound healing and frequency of pain was shorter after laser treatment, but the differences were not statistically significant. Conclusions: Effect treatment with both methods is comparable.

Two measurement methods of selected parameters of soft tissues exposed to laser beam are presented in the paper. The results of optical detection of soft tissue coagulation and damage thresholds are shown. The same detection set-up was used for both measurements.

The paper presents two different techniques: laser melting and laer alloying that use laser beam in order to change the surface layer properties. The microstructure and selected properties (microhardness, wear resistance and chemical composition) of the laser melted ASP 2060 high speed tool steel surface layer, as well as carbon steel laser alloyed with chromium, were investigated. The surface alloyed zones varied in microstructure, its depth, width and Cr content which depends on the thickness of pre-coated powder layer, binder type in the powder slurry and the process parameters (powder and scanning velocity). The electron microprobe analysis of the alloyed layer showed that higher chromium content in the melted zone resulted from the thicker Cr pre-coating as well as slower scanning velocity. Scanning electron microscopy examinations show that dendritic structure of the melted zone becomes evident when an organic binder was used as one of the slurry components. It was also found that lower weight loss is obtained for higher chromium coating thickness as well as higher laser power.

Physical basis of desorption and ablation are presented focusing mostly on the primary and secondary mechanisms and short pulses interaction with materials. Facilities used in pulse laser deposition (PLD) are discussed in respect to the PLD system working with an excimer laser which has been just set up at the Institute of Optoelectronics Military University of Technology. Directions of present and future applications are shown on the basis of the Proceedings of the last two Conferences on Laser Ablation COLA i.e. in Germany (1999) and Japan (2001). Own examinations on the PLD layers of FeAl and Ni₃Al intermetallics produced using an excimer KrF as well as of TiN deposited by means of a Nd:YAG laser are presented.

Contribution of diode laser remelting of high speed steels of grades: HS 2-10-1-8, HS 6-5-2 and HS 10-2-5-8 on microstructure, chemical composition, hardness and cutting performance was under examinations. Increase of hardness was observed in laser remelted zone in comparison to the conventional heat treated steels. Microanalysis SEM EDS showed differences in chemical composition in chosen regions of not treated and laser treated materials. Laser remelting caused the structure refinement and increase of the wear resistance, however, the cutting performance was diminished in respect to the steels not subject to the laser modification. Residual stresses using X-ray method were measured both in steels after conventional heat treatment and subjected to the laser modification.

Laser remelting of titanium alloys by overlapping laser tracks using Nd:YAG or diode laser in nitrogen environment led to the formation of the TiN dominant phase. Residual stress measurements in the TiN phase fabricated in surface layers at tehse conditions revealed the tensile stresses in the range of +500 to +800MPa for overlapping laser tracks produced by Nd:YAG laser and compression ones -33 to -550MPa in the case of the diode laser remelting in one track. Coatings of titanium-nickel produced by remelting of the formerly electro-deposited nickel layer in nitrogen environment were also examined in respect to the formed phases at rapid solidification. Mechanism of TiN formation in surface layers by laser remelting was under discussion.

The paper presents the results of metallographic investigations, measurements of microhardness, measurements of residual streses, abration resistance of high speed steel grades, treated with continuous laser. Hs 6-5-2 and HS 7-4-2-5 steel grades in as-fabricated state annealed, remelted with a CO₂ laser. After laser beam treatment the 1x2 hours tempering was applied at temperature of 560 and 590 °C. The remelting zone consists of dendritic cells and columnar crystals. Measurement of macro-stresses in laser remelting zone using Waissman-Phillips method.

The subject of the analysis and examination is the structure and utilitarian properties of thin ceramic layers placed on the nickel base heat-resistant alloy by plasma spraying method, which later on underwent laser remelting. Examined materials consisting of outer coating ZrO₂+8%wt.Y₂O₃ and NiCrAlY laser are to be used as thermal barriers and protection against high temperature corrosion of heating-resisting alloy on nickel base, applied in internal combustion turbine blades and other construction elements working under stress in high temperature conditions.

This paper presents the results of modification of surface layer properties, obtained the optimised laser alloying of metals insignificant in electrical engineering. Systems with continous, quasi-continuous and pulsed laser beams and different wave lengths were used in the experiments. The structure and composition of the alloyed layers were examined by means of SEM-microscopy and an EDX analyser. The changes of electrical resistivity after laser alloying were measured in a temperature range of 77-450 K. It has been shown that the formation of alloyed lasers for metals with limited solubility (Ag-Sn), insoluable (Mo-Au, Cu-Cr), and even immiscible metals (Ni-Au, Ag-Ni) is possible. It is also possible to obtain alloyed layers with non-metallic additions (oxide). The investigations have shown how alloyed layers with strongly modified properites, especially electrical resistivity, can be obtained by means of different laser beams and various methods for the supplying of alloying elements.

Investigations on bending plates by use of laser beam with rectangular cross-section are presented. Permanent deformation of plate is obtained without external forces, solely under influence of thermal stress induced by local heating of the material. Laser beam of narrow rectangular cross-section was modeled as a linear heat source moving over the plate surface. Temperature distribution in the plastified layer of the material was taken into considerations. The bend angle was investigated as a function of laser beam parameters: power, cross-section geometric parameters, velocity with respect to the material and material parameters of bend plates. It has been proven that effective bending occurs when the material surface temperature is close to the melting temperature. Presented advanced analytical model can be applied in design and control of laser forming of developable surfaces, as well as in other laser processing technologies, hardening, for instance. Derived dependence for the bend angle and curvature can be reduced in special case to well-known expressions describing welding distortions.

Trials of wlding an alloy based on an Ni₃Al phase matrix with a diode laser have been made. In the base metal of Ni₃Al, typical casting structures have been found. The Heat Affected Zone consists of a fine-grained structure, whereas in the weld structure, columnar crystals have been observed. A possibility of joining intermetallic phase-based alloys by measn of a diode laser has been affirmed.

Trials of welding an alloy based on an intermetallic Fe-Al phase matrix with a diode laser have been made. Metallographic research has revealed typical structures, characteristic of welding joints. A possibility of laser joining of Fe-Al alloys has been found.

In the case of the laser welding control by means of the infrared thermographs, the information concerning the quality of the weld is obtained by using a temperature-measuring sensor at a specific point on the welding surface. In order to obtain good efficiency of the laser welding control, the point of the temperature measurement has to be chosen properly. In the present study, an attempt was made to determine an optimal position of the temperature sensor on the welding surface on the basis of comparative analysis of surface temperatures, which were obtained from experimental measurements and model calculations. It refers to laser welding of steel plate sheets.

Laser welding process is unstable because the keyhole wall performs oscillations which results in the oscillations of plasma plume over the keyhole mouth. The characteristic frequencies are equal to 0.5-4 kHz. Since plasma plume absorbs and refracts laser radiation, plasma oscillations modulate the laser beam before it reaches the workpiece. In this work temporary electron densities and temperatures are determined in the peaks of plasma bursts during welding with a continuous wave CO₂ laser. It has been found that during strong bursts the plasma plume over the keyhole consists of metal vapour only, being not diluted by the shielding gas. As expected the values of electron density are about two times higher in peaks than their time-averaged values. Since the plasma absorption coefficient scales as ~N²_e/T^3/2 (for CO₂ laser radiation) the results show that the power of the laser beam reaching the metal surface is modulated by the plasma plume oscillations. The attenuation factor equals 4-6% of the laser power but it is expected that it is doubled by the refraction effect. The results, together with the analysis of the colour pictures from streak camera, allow also interpretation of the dynamics of the plasma plume.

Laser cladding by means of direct remelting of allow powders Stellite SF6 and Metco 16C was applied for production of protective coatings on chromium steel substrates of composition close to that of the gas turbine blades which operate in extremely aggressive environment. For sample preparation a 1.2 kW cw CO₂ laser with powder jet coaxial to the laser beam was used. Compared to previous experiments the controlled preheating of substrate at temperatures around 500-720°C was applied and resulted in crack-free coatings.

In this paper, results of investigations concerning the influence of high power diode laser surface modification of titanium alloy TO4 on structure and properties of the top layer are presented. The results showed that it's possible to produce high quality top layer of 0.15 to 0.7 mm thick. The hardness of the top layer is up to 3100 HV0.2, and the hardness of substrate material is under 200 HV0.2.

The Surface Laser Alloying (SLA) process using High Power Diode Laser (HPDL) with rectangular beam spot and uniform energy distribution across the spot was investigated. The surface of substrate tool steel was alloyed with cobalt based powder injected directly to the weld pool. The parameters investigated were laser power, traveling speed and powder feeding rate. The results showed that it's possible to produce high quality surface layer alloyed with diode laser. Thickness of the alloyed layer is in a range from 0.7 up to 2.5 mm, and its micro hardness exceeds 1000 HV0.2.

In this paper, results of investigations on the shape of weld pool during High Power Diode Laser (HPDL) welding are presented. The results of tests showed that the shape of weld pool and mechanism of laser welding with a rectangular pattern of 808 nm laser radiation differs distinctly from previous laser welding mechanisms. For all power densities the conduction mode welds were observed and weld pool geometry depends significantly on the welding parameters.

In this article, changes in structural and electrical properties of surface coatings were investigated after laser remelting. The surface Ni-coating under investigation has been obtained by plasma spraying. Surface remelting was carried out under a pulse Nd:YAG laser. Microstructure evolution and phase identification was investigated by means of optical and scanning microscopy and X-ray microanalysis. Laser remelting eliminated defects and porosity of a surface layer and suppressed the oxide phase. The electrical resistivity of a plasma sprayed layer was decreased and the temperature resistivity coefficient was increased due to these structural changes.

This article presents some investigations of a laser alloyed surface layer of nickel doped with gold and of copper doped with aluminum. The velocity of the convectino flow in the laser pool predicted by computation implies that there may exist good miscibility for the range of components different from those obtained by the conventional method. This indicates a predominant role of the Marangoni convection for mixing elements. Some metallurgical cross-sections of Ni-Au; Mo-Au; Cu-Al; Cu-Au layers, alloyed by an Nd-YAG laser, for different contents of doping elements are presented. They may be interesting information about miscibility of these metals during laser pulse τ₁=4ms.

The laser surface melting of AA2024-T3 alloy modified a structure of surface layer resulting in cells and/or cellular dendrites of very fine microstructure. There are mainly two phases, i.e. primary solid solution and precipitated Al₂Cu phase, around the cell boundaries. Some minor traces of Fe and Mn are also present. The estimated decrease of Cu content in precipitates is approximately 25%. The susceptibility to pitting corrosion of laser melted AA2024-T3 surfaces characterised by pitting potential was not improved in comparison with as-received material, mainly due to non-uniform structure at subsequent laser tracks.

Effective and reliable manufacturing of Micro (Opto) Electro Mechanical Systems (MEMS and MOEMS) requires extensive measurements of their mechanical and material parameters including shape, displacements, deformation, vibration mode profiles and material constants. Knowledge of these parameters at various technological and product life stages is of fundamental importance for MEMS and MOEMS design process. Complex structures are subject to wide range mechanical, thermal and electric loads and their testing methods should provide data about their behavior with nanometer sensitivity and spatial micrometer resolution. In the paper numerous examples of MEMS and MOEMS testing by laser interferometric methods are presented. The methods include classical heterodyne and grating interferometry, interferometric tomography, digital holographic and speckle interferometry. The studies presented were conducted in Optical Engineering Division, Institute of Micromechanics and Photonics of Warsaw University of Technology.

In the paper experimental results of microbeam/cantilever vibration measurements are presented. The cantilever under investigation is used as a sensor in a Atomic Force Microscope. Double-Beam Digital Interferometry with time averaging and interferogram processing was used for optimization of vibration mode visualization. Several two-frame methods with phase step between the frames were compared with the four-frame method with phase step π/2 between consecutive frames. The experimental results obtained prove that the four-frame method is the most appropriate for further quantitative amplitude and phase analysis.

In the report the arrangements of laser interferometers for machine history are presented; the laser interferometer LSP30 for investigation of geometry of machine tools, the setup for inspection of ball screw and laser liner for CNC machine. Outstanding feature of the interferometers is the stabilization system of laser frequency using surface stabilized ferroelectric liquid cells (SSFLC).

The paper presents influence of laser radiation parameters on velocity of encrustation removal from artworks and heritage architectural objects. Influence of laser fluence quantity, pulse duration and pulse repetition rate on parameters of graphite layer ablated from aluminum substrate (temperature, pressure density and velocity of removal) is discussed on the basis of developed numerical model. Moreover, influence of graphite modernisation itself (pores and percentage concentration of gas and water) on parameters of ablation layer is presented. In conclusion, selected experimental results of influence of laser wavelength and fluence on velocity of encrustation removal for different heritage objects are given as well as remarks on laser cleaning process are presented.

Results of paper cleaning by means of the 532 nm Nd:YAG laser (pulse length 6 ns, fluency 0.3-0.6 J/cm²) are reported and discussed. Results of the surface cleaning of the paper samples originating among others from the two oldest Polish Bibles (XVI c.) are examined by the SEM technique after laser processing. For the process diagnostic the LIF spectra of paper samples recorded under excitation at 266 nm and 532 nm before and after processing are analysed and spectra of the non-contaminated samples are taken for reference. The presence of contamination and also cleaning history is evidenced in the recorded spectra. Comparison of SEM images and also the spectral characteristics of the originally contaminated samples before and after laser treatment confirm results of the laser cleaning.

There is still interest in improving electrostatic precipitator (ESP) collection of fine particles (micron and submicron sizes). However, it is not yet clear whether the turbulent flow patterns caused by the presence of electric field and charge in ESPs advance or deteriorate fine particle precipitation process. In this paper reuslts of the Particle Image Velocimetry (PIV) measurements of the particle flow velocity field in a wire-to-plate type ESP model with seven wire electrodes are presented. The PIV measurements clearly confirmed formation of the secondary flow pattern changes caused by the strong interaction between the primary and secondary flows are more pronounced for higher operating voltage (high electrohydrodynamic number NEHD) and lower primary flow velocity (lower Reynolds number Re).

Local heating of metal objects by means of a laser beam gives opportunity to obtain their permanent deformations in a controlled manner. Very small changes of the shape are utilized in mutual positioning of parts and subassemblies. This touch-less method has found applications in production of miniature electro-mechanical and electronic devices, entering the area of optoelectronics lately. Basic contructional solutions of support structures designed to utilize laser positioning technique are presented. The systems apply laser-induced bending deformations or contraction due to material upsetting. Bending under influence of heating by non-moving laser beam was analyzed with use of the finite element method. Steep temperature gradient on the cross-section of the object is needed to obtain permanent bending deformation in the direction of the heat source. Bending of a steel plate, 1 mm thick, was analyzed in a sequence of three cycles of heating and cooling. Time-run of the bending process resulting from the simulation is similar to those, observed in physical experiments. Precision of calculations is strongly influenced by the values of the absorption and thermal expansion coefficients.

The article describes trends in the development of gradient techniques used for the analysis of the spatial distribution of the breakdown coefficient of a gas different to the surrounding atmosphere. Depending on the modification made to the Schlieren technique, it was possible to measure in real time the mass distribution with a different range and ratio. In the optical system, periodic patterns (rasters) as well as the arrangements of Rife prisms were used. Carbon dioxide and propane were used as gaseous pollutants of the air. The new solution proposed by the authors has turned out to be an effective tool for the analysis of gaseous pollutant distribution processes.

Thermal defocusing and thermal deflection can be applied for real time evaluation of the contents of gas mixture. The preliminary results for nitrogen peroxide are presented.

The short history of the laser warning receivers (LWR) development was presented by the tank systems. The theoretical analysis concerns the device which applies the special uncooled multispectral detectors. The theoretical results are confirmed by measurements in real conditions. Predicted ways of development of the LWR devices and the proceeding changes extending their possibilities were shown.

The layout of integrated optical system compromising the basis of proposed solution of double laser interferometer composed of two integrated Michelson's interferometers is presented and shortly discussed. Such an integrated system is designed for work with two lasers of different wavelength. It may serve for mapping surfaces and deformations of objects under investigation with the use of simultaneous recording of two mutually orthogonal gratings, each one composed of equidistant, parallel interference fringes projected onto the surface of such an object. The picture resulting two-coloured is recorded with the digital camera and may be used for obtaining these maps and deformations directly or in the indirect way after suitable digital processing applied to each colour component separately.

The contactless photoelectromagnetic (PEM) method of determining carrier lifetimes in semiconductors needs high frequency modulation of laser light. Recently the acoustooptical modulation technique was used for this purpose. In this paper the influence of frequency of acoustooptical modulation on time dependence of intensity of laser light was examined. One can recognize the importance of taking into account in contactless PEM investigations of carrier lifetime the dependence of amplitude of illumination on frequency of laser beam acoustooptical modulation.

The construction and the principle of operation of an instrument introduced to the measurement of the dynamic dislocations of solid body surfaces are presented in the study. The phenomenon of speckling of laser light scattered through the rough surface was utilized. A speckle pattern was recorded by using a digitally-controlled diode matrix. Many configurations of optical arrangements for generating patterns and for mapping them into the detector plane were tested. The developed instrument can measure all components of linear and angular dislocations. The best efficiency was obtained in the measurements of the transverse component of dislocation. The range and ratio of measurement are strongly dependent on the laser light power and on the quality of the photoelement used.

The study assesses the effectiveness of the application of speckle methods in the testing of natural and artificial composites. Most of attention has been given to the testing of wood. This is due to a particular and constantly growing role of this construction material. Comparative tests were performed by coherent speckle photography methods, by the methods of speckle photography in white light and by ESI methods. Quite unexpectedly, the classical coherent speckle photography in the out-of-plane version has proved to be the most sensitive method in non-destructive tests.

The signal from the piezoelectric foil illuminated with modulated light depends on the kind of liquid in contact with the foil. The dependence of the signal on the concentration of alcohol in the aqueous solutions was examined. The results of the experiment indicate that practical applications of this method are possible.

This paper presents problems related to differential measurements of the energy of pulse light sources with the use of pyroelectric sensors. Methods based on the use of differential measurements enable elimination of the background signal. An original, designed and constructed conversion system based on the differential method is described.

In this paper I would like to present the necessity of taking into account a deformation of laser radiation in the real atmosphere while conducting measurements providing data for Intelligent Transport Systems.