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Scratch test is regularly used for assessment of cohesive and adhesive strength of thin films and coatings. By default, its evaluation is based on analysis of depth-load-time record and microscopic observation of residual scratch groove. The visual analysis of the residual groove provides the most detailed description of the final damage of the surface (crack patterns, extent of plastic deformation, delamination, etc.), but it may be a time demanding approach. Although the continuous recording of indenter penetration depth and applied load offers instantaneous information about the performance of the tested material, it may not provide sufficient description of the sample’s deformation behaviour. Therefore, other complementary techniques for description of the deformation response to scratch loading are desirable. Continuous recording of acoustic emissions (AE) generated during the test could be a possible solution. It is especially the ability of AE method to detect the very first and even subsurface failures of the material that is of the most importance and otherwise inaccessible by standardly used techniques. What is more, it is a non-destructive and real-time method. In principle, AE method can be beneficially employed for a wide range of materials explored via scratch test. The strength of the AE analysis of the nano/micro scratch test will be demonstrated on various types of materials including optical thin films, durable metal and hard ceramic films as well as bulk laser cladding. Selected phenomena and features of the use of AE during scratch testing will be presented, including effect of scratch load on character of AE records (burst vs. continuous) for TiO2 on glass, subsurface damage of SiC films on silicon and selective failure of hard carbide phase embedded in a metal matrix in case of laser re-melted layers.

Butt welding of commercially pure titanium Grade 1 and Ti6Al4V alloy sheets using a pulsed Nd:YAG laser KLS 246 - 102 LASAG were carried out to determine optimal values of pulse energy and pulse length to create completely penetrated weld. Surface peak power density of about 3.105 W.cm−2 was found as an optimal value. Weld dimensions, both face width and penetration depth, are found to be proportional to increasing energy and decreasing pulse length. Gentle sagging and root penetration were revealed by means of contact surface profilometry. The nanohardness tests on transverse cross-sections detected approximately 50% higher hardness in the fusion zone than in the base material.

Background Short-term treatment for people with type 2 diabetes using a low dose of the selective endothelin A receptor antagonist atrasentan reduces albuminuria without causing significant sodium retention. We report the long-term effects of treatment with atrasentan on major renal outcomes.Methods We did this double-blind, randomised, placebo-controlled trial at 689 sites in 41 countries. We enrolled adults aged 18-85 years with type 2 diabetes, estimated glomerular filtration rate (eGFR) 25-75 mL/min per 1.73 m(2) of body surface area, and a urine albumin-to-creatinine ratio (UACR) of 300-5000 mg/g who had received maximum labelled or tolerated renin-angiotensin system inhibition for at least 4 weeks. Participants were given atrasentan 0.75 mg orally daily during an enrichment period before random group assignment. Those with a UACR decrease of at least 30% with no substantial fluid retention during the enrichment period (responders) were included in the double-blind treatment period. Responders were randomly assigned to receive either atrasentan 0.75 mg orally daily or placebo. All patients and investigators were masked to treatment assignment. The primary endpoint was a composite of doubling of serum creatinine (sustained for >= 30 days) or end-stage kidney disease (eGFR = 90 days, chronic dialysis for >= 90 days, kidney transplantation, or death from kidney failure) in the intention-to-treat population of all responders. Safety was assessed in all patients who received at least one dose of their assigned study treatment. The study is registered with ClinicalTrials. gov, number NCT01858532.Findings Between May 17, 2013, and July 13, 2017, 11 087 patients were screened; 5117 entered the enrichment period, and 4711 completed the enrichment period. Of these, 2648 patients were responders and were randomly assigned to the atrasentan group (n=1325) or placebo group (n=1323). Median follow-up was 2.2 years (IQR 1.4-2.9). 79 (6.0%) of 1325 patients in the atrasentan group and 105 (7.9%) of 1323 in the placebo group had a primary composite renal endpoint event (hazard ratio [HR] 0.65 [95% CI 0.49-0.88]; p=0.0047). Fluid retention and anaemia adverse events, which have been previously attributed to endothelin receptor antagonists, were more frequent in the atrasentan group than in the placebo group. Hospital admission for heart failure occurred in 47 (3.5%) of 1325 patients in the atrasentan group and 34 (2.6%) of 1323 patients in the placebo group (HR 1.33 [95% CI 0.85-2.07]; p=0.208). 58 (4.4%) patients in the atrasentan group and 52 (3.9%) in the placebo group died (HR 1.09 [95% CI 0.75-1.59]; p=0.65).Interpretation Atrasentan reduced the risk of renal events in patients with diabetes and chronic kidney disease who were selected to optimise efficacy and safety. These data support a potential role for selective endothelin receptor antagonists in protecting renal function in patients with type 2 diabetes at high risk of developing end-stage kidney disease. Copyright (C) 2019 Elsevier Ltd. All rights reserved.

Desorption nanoelectrospray (nanoDESI) was described in 2007 and it represents a miniaturized version of desorption electrospray without the assistance of the nebulizing gas. Compared to DESI, a nanoelectrospray tip (2 ± 1 μm I.D.) generates primary charged droplets of smaller sizes and lower spray liquid flow rates. This is the first report on utilization of nanoDESI for mass spectrometry imaging (MSI). Its new coupling with a Q-TOF instrument allowed faster mass spectra acquisition (4 Hz) essential for MSI of fine surface details. To evaluate nanoDESI potential for mass spectrometry imaging, etched glass substrates with Rhodamine B patterns of different dimensions were prepared. The Rhodamine B lines were analysed in 1D scanning mode and their width was determined experimentally by nanoDESI measurement. The experimental data revealed that the lateral resolution of nanoDESI is close to 30 μm along the x-axis (orthogonal to the inlet). 2D scanning mode confirmed good resolution along both axes as dye squares with dimensions about 60 μm × 60 μm were easily distinguished. The low flow rate of the spray liquid reduced undesirable analyte washing effects, which allowed repeated scanning analysis of the surface. The presented results demonstrate the applicability of nanoDESI for high surface resolution mass spectrometry imaging.

A brief review is focused on laser micromachining of materials. Micromachining of materials is highly widespread method used in many industries, including semiconductors, electronic, medical, and automotive industries, communication, and aerospace. This method is a promising tool for material processing with micron and submicron resolution. In this paper micromachining of glass, silicon, and ceramics is considered. Interaction of these materials with laser radiation and recent research held on laser material treatment is provided.

The finite-element tool SYSWELD (ESI Group, Paris, France) was adapted to simulate pulsed-laser seam welding. Besides temperature field distribution, one of the possible outputs of the welding simulation is the amount of absorbed power necessary to melt the required material volume including energy losses. Comparing absorbed or melting energy with applied laser energy, welding efficiencies can be calculated. This article presents achieved results of welding efficiency estimation based on the assimilation both experimental and simulation output data of the pulsed Nd:YAG laser bead on plate welding of 0.6-mm-thick AISI 304 stainless steel sheets using different beam powers.

This paper is dedicated to laser engraving and drilling process of the alumina ceramics. Both processes are characterized by exquisite features in comparison with conventional ones. The main benefits are high speed, high precision and good quality along with flexibility. Moreover ceramics are hardly processed by conventional methods due to their high hardness and brittleness. Analysis of Nd:YLF laser engraving alumina ceramics concerning the influence of parameters like output power, processing speed and number of runs on various mark characteristics was carried out. Mark width, mark depth and contrast were evaluated and it was found out that output power determines both mark depth and width. Higher power caused generation of deeper and wider marks characterized by high contrast. Processing speed controls the overlapping of spots and the laser-material interaction time, thus having impact on the mark depth and contrast. Laser drilling was examined in dependence of output power that had crucial effect on the hole depth not on diameter. The research clarified that high output powers are necessary for producing deep holes so as high output powers together with low processing speeds are the optimal parameters to get maximal mark width and depth with satisfactory quality during engraving. Samples were analyzed using confocal microscope and contact profilometer.

Weld geometric characteristics in laser overlapping spot welding of 0.6-mm AISI 304 stainless steel sheets were investigated. A pulsed Nd:YAG laser with maximal average power of 150 W was used for welding experiments with different laser beam energies in the range of 3.5 J to 6.2 J, keeping all other processing parameters constant. The main objective of these experiments was to study the effect of energy changes and to identify the welding mode in dependency on the beam effective peak power density. Each weld surface and its cross section were analyzed using a laser scanning confocal microscope. The spot diameter on the specimen, weld width, and penetration depth were measured. Three-dimensional surface reconstruction was realized to describe the effect of energy changes on weld surface properties.

BACKGROUND DATA AND OBJECTIVES: Nd:YAG laser radiation has been applied in treatment of dentine hypersensitivity; dentine melt created after irradiation on a tooth surface can occlude open dentinal tubules. Different conditions (energy of pulses, number of successive irradiations, and type of dye agent) have been reported in the literature. In our study, different conditions are compared and the most suitable ones are suggested.One hundred nine dentine samples prepared from extracted human third molars in the form of 2- or 3-mm thick discs and facets from an outer convex surface of a root were irradiated by pulses with duration 0.3 ms and beam diameter 0.3 or 0.6 mm. The laser repetition rate was 15 Hz. Energies per pulse have been changed from 20 mJ to 250 mJ (the corresponding energy densities rho are 22 and 275 J/cm(2) for the beam diameter of 0.3 mm). Dyes including tartrazine, carmine indigo, erythrosin, and methylene blue have been used to cover dentine surfaces and to increase absorption of laser radiation. Irradiated dentine surfaces have been investigated using scanning electron microscopy.Sealing of open dentinal tubules can be accomplished even without dyes, provided that a sufficiently intense laser radiation level is used. To avoid damage to the dentine's surface the use of dyes is necessary. Erythrosin has been found to be the best agent, and closing of dentinal tubules occurred after four doses of irradiation with 30-mJ pulses with a beam diameter of 0.6 mm (energy density rho = 8.25 J/cm(2), total energy density rho(T) = 33 J/cm(2)). The upper limit has been reached using four doses of irradiation by 90-mJ pulses with a beam diameter of 0.3 mm (rho = 99 J/cm(2), rho(T) = 396 J/cm(2)).Occluding dentinal tubules can safely and effectively be accomplished using pulsed Nd:YAG laser radiation provided that the dentine surface is covered with erythrosin solution.

Dentin of human teeth is a vital hydrated tissue. It is strongly sensitive to dehydration and drying that are commonly used in preparation of samples for scanning electron microscopy. Experience in examination of dentine surfaces of extracted human third molars using contact mode atomic force microscopy under moist conditions is described. The examined dentine surfaces are modified by laser radiation produced by a pulsed Nd:YAG laser that leads to sealing of open dentinal tubules under suitable conditions that are reached after covering dentine surfaces with dye agents. Out of four investigated dye agents erythrosin solution in water has been found the most suitable and the lower and upper limits of pulse energies for sealing of dentinal tubules have been set.

Deep penetration welding is a typical industrial application of high power lasers, where plasma can be generated above the keyhole. Thanks to the plasma plume presence welding process can be controlled on-line by means of the plasma intensity measurements. Various on-line monitoring methods have been developed in research centers all over the world. Goal of them is to enable promptly operator action to avoid enormous economical looses if un-expected defect is detected. Our laboratory was participated in project CLET - “Closed loop control of the laser welding process through the measurement of plasma” as a responsible partner for developed system testing both in the laboratory with pulsed Nd:YAG laser and in the real welding facility with high power continual CO2 laser. Control system is based on the electron temperature computation from the relative intensities of couple of emission lines belong to certain metal ion present in plasma plume. Our experiment was realized using Ocean Optics HR2000+ spectrometer within the stainless steel tube longitudinal welding. Several couples of emission lines were tested to acquire a good signal at actual welding conditions. Then power calibration was made to obtain the electron temperature dependence on increasing power. Samples were prepared for microanalysis and measured by laser confocal scanning microscope to find optimal power range for full penetrations achieving without thermal distortion of the tube or weld humping. Numerical model of the remelted area cross section was made to display temperature distribution dependence on increasing power.

Research of the optical radiation interaction with human tooth tissues has started early after the first laser construction. Absorptivity of the particular tissue is dependent on the wavelength, thus CO 2 , Er:YAG and Nd:YAG lasers were used in many experimental works all over the world. Near infrared radiation of the pulsed Nd:YAG laser was found to be suitable for dentine hypersensitivity treatment by sealing of the open tubules with melted and re-solidified dentin. Series of experiments were performed to find suitable process parameters in the laser laboratory equipped with the industrial pulsed Nd:YAG laser system. Tooth samples were prepared and classified into five groups according to their different degree of the surface grinding and polishing. Two types of antireflective agents, erythrosine and black ink, were applied on the samples surfaces. Coated samples and reference ones without any agents were treated with a set of increasing pulse energy values. Pulse frequency, pulse length, laser beam diameter on the sample surface and relative speed remained constant. Lines of the melted spots were displayed by confocal microscope; surface profiles were scanned by contact profilometer. Dimensions of the dentine melted spots were extracted from the measured data and their dependence on the laser pulse energy, degree of the surface grinding and type of antireflective agent were evaluated.

A method for on-line monitoring of the joint penetration depth is reported, based on the spectroscopic analysis of the optical emission collected from laser–metal interaction zone. This technique has been applied to quite diverse welding procedures (c.w. CO2 laser, cw fiber laser and pulsed Nd:YAG laser) of stainless steel plates. Although the acquired spectra reveal different characteristics according to the employed laser source, a discrete contribution of several iron lines can be highlighted in both types of investigated welding processes. Starting from the measurement of the intensities of those lines it is possible to calculate the plasma electron temperature, which was found to decrease as far as the laser power is enhanced together with the penetration depth, in static as well as dynamic conditions. Such a behavior does not correspond to a real decrease of the plasma plume temperature but has to be ascribed to the position of the optical collimator collecting light only from the top of the keyhole. Indeed, for deeper penetrations the hottest core of the plume moves down into the vaporized capillary so that the plasma temperature measured on top of the keyhole appears lower at higher incident powers. The electron temperature signal could be useful for the development of a feedback loop system of the laser power to control the weld penetration depth.

Laser beam of the infrared pulsed Nd:YAG laser was used to re-melting PVD coatings on the steel substrates. Chemical composition of these layers contains carbide Cr 3 C 2 with alloy NiCr or nitrides TiN, TiAlN, TiAlSiN and CrAlSiN. First coatings were prepared by method of high velocity oxygen fuel (HVOF) that protects the machine component surfaces from abrasion, corrosion or ensures thermal isolation, nitrides by PVD (Physical Vapor Deposition). Processing parameters such as pulse energy, pulse length and frequency were optimized in many experiments to achieve the sufficient surface energy density to melting without vaporization of the material. Multimode beam diameters about some millimetres were computed and adjusted in the suitable distance from focus plane. High laser power re-melting decreases their porosity, increases adhesion to basic material. In case of high laser energy gas vapours escape from basic material and cause fissures, re-melted surfaces have to be carefully controlled. New approach to evaluation of the quality surface structure was realized by laser confocal microscopy. Direct measuring or 3D surface model is possible with resolution less than hundred nanometres, depressions along laser beam path or rises on the laser spot edges were determined. Particles and grains with dimensions about one micron in re-melting structures can be observed better then by optical microscopy. Parallel measurements of the surface roughness were realized by the contact inductive profilometer Talysurf, collected data were displayed by software tool Talymap in a plane or spatial pictures.

Pulsed Nd:YAG laser with maximal power 150 W is used in our laboratory to cut, drill and weld metal and non-metal thin materials to thickness 2 mm. Welding is realized by fixed processing head or movable fiber one with beam diameter 0,6 mm in focus plane. Welding of stainless and low-carbon steel was tested before and results are publicized and used in practice. Now the goal of our experiment was optimization of process parameters for aluminum that has other physical properties than steels, lower density, higher heat conductivity and surface reflexivity. Pure alumina specimen 0,8 mm and Al-Mg-Si alloy 0,5 mm prepared for butt welds. Problem with surface layer of Al2O3 was overcome by sanding and chemical cleaning with grinding paste. Critical parameters for good weld shape are specimen position from beam focus plane, pulse length and energy, pulse frequency and the motion velocity that determines percentage of pulse overlap. Argon as protective gas was used with speed 6 liters per second. Thermal distribution in material can be modeled by numerical simulation. Software tool SYSWELD makes possible to fit laser as surface heat source, define weld geometry, and make meshing of specimen to finite elements and compute heat conduction during process. Color isotherms, vectors, mechanical deformations and others results can be study in post-processing.© (2007) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Material surface modification was carried out by laser alloying technology with an additional material. The final effects are based on micro-structural changes in the surface layer, furthermore by changing the material composition in the surface. Sic powder was applied on CSN 41 20 10 steel into melting pool generated by interaction with the moving C02 laser beam. Numerical modelling of the temperature field on the substrate appears like a good way to optimalization of process parameters. The final surface structures are presented and analysed by scanning electron microscopy. The microhardness of treated layers in comparison with substrate is described too.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Symptom of cervical dentine hypersensitivity attacks from 10% to 15% of population and causes an uncomfortable pain during contact with any matter. Sealing of open dentinal tubules is one of the methods to reach insensibility. Laser as a source of coherent radiation is used to melt dentine surface layers. Melted dentine turns to hard mass with a smooth, non-porous surface. Simulation of this therapy was made in vitro by means of LASAG Nd:YAG pulsed laser system KLS 246-102. Eighty human extracted teeth were cut horizontally to obtain samples from 2 mm to 3 mm thick. First experiments were done on cross section surfaces to find an optimal range of laser parameters. A wide range of energies from 30 mJ to 210 mJ embedded in 0,3 ms long pulse was tested. Motion in X and Y axes was ensured by a CNC driven table and the pulse frequency 15 Hz was chosen to have a suitable overlap of laser spots. Some color agents were examined with the aim to improve surface absorption. Scanning Electron Microscopy was used to evaluate all samples and provided optimal values of energies around 50 J.cm-2. Next experiments were done with the beam oriented perpendicularly to a root surface, close to the real situation. Optical fibers with the diameter of 0,6 mm and 0,2 mm were used to guide a laser beam to teeth surfaces. Laser processing heads with lens F = 100 mm and F = 50 mm were used. The best samples were investigated by means of the Atomic Force Microscopy.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Pulsed laser system LASAG with maximal average power 150 W is used in our laboratory for experiments with various kinds of materials, process parameters optimisation for cutting, welding, drilling and surface treatment. Alignment of optical elements and good laser beam quality is critical parameter for successful result of laser treatment. Active medium - crystal in solid state laser is warmed up during laser action, because only some percent of input electrical power is turn to optical energy. Warm crystal has properties like a thick lens, which optical power is dependent on process parameters and kind of resonator. Also some defects in optical system - dirty or damaged mirrors or lens must be detect. Properties of non-visible near infrared beam can be tested by means of laser beam analyzer SPIRICON. In our system there are movable and changeable end mirrors and diaphragms to obtain five different types of resonators - basic one for welding and fibre applications and four ones for fine cutting and drilling. Measurements of beam profile for all these resonators were made with safety values of pulse length, energy and frequency. Control of losses in optical system was made to inspect quality of optical elements. Also measurement of laser beam outputting from three different fibre processing heads was realised. Control measurements on continual industrial Nd:YAG laser system were made. All data and capture pictures are stored and practical lessons for students in next school years were prepared.

Structures analysed in that paper were produced by the laser cladding technology on CSN 41 1373 steel with a Ni-based alloyed powder "K50" using CO2 laser. The point of view of an investigation is the structure mapping and an experimental verification of the process parameters. A dendritic structure in individual regions of the selected clad layer and material composition are point of balance of micro-analyses which were carried out by the scanning electron microscopy and analysis of elements hence distribution of material.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

CVD diamond has many outstanding physical properties. Because of its extreme hardness, this material is difficult to cut and polish and laser cutting and shaping is a technology of choice. Thick polycrystalline diamond layers were deposited by microwave plasma enhanced chemical vapor deposition on silicon substrates. After synthesis, the silicon substrate was dissolved in an acid mixture and diamond wafer has to be cut into desired shapes according to their future use. With LASAG Nd:YAG pulsed laser system KLS 246-102 we found cutting parameters for different thickness of diamond wafers from 0,1 mm to 0,7 mm. A special support with connection to vacuum was developed to keep small and light parts fixed during processing. To avoid undesirable cracks, laser scribing was used at first. Laser pulse with energy 30 mJ-200 mJ according wafer thickness and velocity 3mm.s-1-15 mm.s-1 goes two or four times along cutting lines. High temperature is the origin of black graphite layers, where absorption of laser radiation continues. Peak power contained in 0,2 ms pulse was up to 1000 W. Developed method helps to prepare CVD diamond samples of any desired shape.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Laser cladding is one of the technologies of material surface treatment. A series of laser-clad specimens have been produced using continual 2,5 kW CO2 laser. There is introduced a description of the powder injection laser cladding method in the present paper. For some numerical calculations of laser beam induced temperature field in treated material were used the finite difference method and the finite element method. Results of this modeling led to an optimalization of cladding process parameters. Some layers of Ni-based alloy K50, Stellit6 alloy and SiC powders were applied on low-carbon CSN 11 373 and CSN 12 010 steels. Shape characteristics and some properties such as microhardness of clad layers in comparison with substrate values were analyzed.© (2004) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Both types of industrial lasers, CO 2 and Nd:YAG, are used for welding with wide range of maximal power values. Successful results of laser welding depend on many different factors: energy, diameter, mode structure, polarization and focus position of laser beam; thickness, accurate positioning and gap of welded parts, kind of shielding gas. With LASAG Nd:YAG pulsed laser system KLS 246-102 we made optimization of welding parameters for different metals 0.5 mm thick and some types of the weld geometry. Our experimental results were used for welding of the side joint of the steel motor covers. These precious parts are used in automobile racing models. Finite elements model is used to predict a heat affected zone.

This paper describes a numerical finite element method modeling of laser applications, especially laser cutting and drilling a steel, concrete or brick. In the first part of this contribution there is a very brief description of laser processing in metal (a kind of carbon steel) and non-metal material (concrete and brick), possibility of mathematical modeling and needful parameters for this modeling. One of the systems, that uses this method, is ANSYS. The ANSYS computer code is a large-scale multipurpose finite element program, which may be used for solving several classes of engineering analyses, for example thermal analyses, that calculates the temperature distribution and related thermal quantities in a system or its components. The main part of this paper deals with examples of temperature field computed by ANSYS in carbon steel, concrete and brick after incident of the high-power laser beam upon their surfaces. In conclusion we compare various theoretical results mutually and also with practically obtained facts.

This paper describes a possibility of mathematical modeling of laser applications, especially laser cutting and drilling and its use in practice. In the first part of this contribution there is a very briefly description of contemporary use of high-power lasers in industry and also basic principles of interaction between laser beam and treated material. Next part of the paper deals with a mathematical modeling of temperature field. Two numerical methods are used for the calculation of the temperature field: the finite difference method and the finite element method. Two examples of results of these both methods are demonstrated and some problems occurring when creating the matheniatical models are described. In the conclusion we made a brief comparison between theoretical and experimental results.

This article is focused on the laser surface remelting of the steel samples with predefined overlapping of the laser spots. The goal of our experimental work was to evaluate microstructure and hardness both in overlapped zone and single pass ones for three kinds of ferrous metals with different content of carbon, cast iron, non-alloy structural steel and tool steel. High power fibre coupled diode laser Laserline LDF 3600-100 was used with robotic guided processing head equipped by the laser beam homogenizer that creates rectangular beam shape with uniform intensity distribution. Each sample was treated with identical process parameters - laser power, beam diameter, focus position, speed of motion and 40% spot overlap. Dimensions and structures of the remelted zone, zone of the partial melting, heat affected zone and base material were detected and measured by means of laser scanning and optical microscopes. Hardness progress in the vertical axis of the overlapped zone from remelted surface layer to base material was measured and compared with the hardness of the single spots. The most hardness growth was found for cast iron, the least for structural steel. Experiment results will be used to processing parameters optimization for each tested material separately.

In this paper, there is described the influence of various modifications of the laser resonator on the energy of laser radiation studied for the application of material drilling. We used pulsed 150W Nd:YAG laser from LASAG AG company, Switzerland. This laser was developed for industrial material processing - cutting, welding and drilling. The diameter and divergence of the output laser beam can vary by replacement of optical elements in the laser resonator and by change of the distance between them. Heating of Nd:YAG crystal during laser action resulting in its function as an internal lens has an important effect on a beam quality. This quality is characterized by a beam parameter product depending on a charging power and type of resonator. The goal of our experiment is to find minimal parameters for cutting and drilling of some metallic sheets with thickness from 0.1 mm to 10 mm and to verify an increasing beam quality by reducing a laser output power and by modification of a resonator arrangement. Nitrogen was used as an assist gas. Measured experimental results were summarized in graphs and tables and were prepared for quick reference of laser parameters used for processing various work-pieces.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.