Three-dimensional (3-D) microstructuring of photosensitive glass is demonstrated by using femtosecond (fs) laser for Lab-on-chip, in other words, micro total analysis system (μ-TAS), application. The fs laser direct-write process followed by a thermal treatment and chemical etching in a HF aqueous solution produces true 3-D hollow microstructures embedded in the photosensitive glass. This technique is applied for manufacturing a microfluidic structure inside the glass. Mixing of two kinds of aqueous solutions is demonstrated in the fabricated structure. A freely movable microplate is also fabricated inside glass to control a stream of reagents in the microfluidics. In the meanwhile, this technique is applied for integrating microoptics like micromirror and micro beam splitter in the glass chip for optical analysis of reactants produced in the microfluidics. This paper also discusses the mechanism of fs laser and photosensitive glass interaction.

Laser amorphization of glass-ceramics (LAGC) is investigated by optical pyrometry and video recording. Due to this new knowledge, the mechanism of local LAGC is made clear as a phenomenon leaded by thermal kinetic. The required power density and temporal range of CO₂-laser irradiation for amorphization of a typical glass-ceramic (GC) α-TiO₂• 2MgO • 2Al₂O₃ • 5SiO₂ are defined. Fabrication of a wide range of microoptical components such as lenses, lens arrays, wave-guides, geodesic lenses ... are demonstrated with methods for controlling of their parameters.

Laser-induced technological chemical processes can significantly contribute to the development of new methods for micro treatment of materials and hence to the broadening of the application spectrum of laser microtechnology. In this paper three typical laser-activated chemical technological methods in liquids, gases and solids and their possible applications are presented and discussed: (1) Laser-induced liquid-phase jet-chemical etching of metals. In this method, laser radiation which is guided from a coaxially expanding liquid jet-stream initiates locally on a metal surface a thermochemical etching reaction, which leads to a selective material removal at high resolution (<1 μm) and quality of the treated surface; (2) Local photon-plasma induced synthesis of thin film coatings. This technological method is based on thermochemical CVD processes taking place in a photon-initiated stationary plasma maintained in the electromagnetic optical field of a high-power cw-CO₂ laser radiation. This method allows synthesis of thin-film coatings in the open-air atmosphere without using vacuum or reaction chamber; (3) Laser-induced photochemical modification of the optical properties of polymers. This method is based on the local controllable change of the polymer structure leading to modification of the refractive index in the treated area. By numerous independently adjustable laser radiation parameters, for instance wavelength and irradiation dose, the modification process can be controllably driven in order to generate desired functional properties.

The overview presents the state-of-the-art in application of laser assisted Rapid Prototyping (RP) methods and their possibility to produce Functionally Graded Material (FGM) models. As Rapid Prototyping is a stepwise process constructing the object layer by layer, material composition may be changed from layer to layer and/or within the layer, this way a FGM object with 3D material gradient can be created. The free-form FGM model with engineered shape, composition, structure and even protective coating can be manufactured within one single process. Several techniques are analyzed and particular attention is paid to the lateral and coaxial powder injection into the laser beam. These technologies are shown as most effective tool for creation of FGM parts. The best results are obtained in laboratory conditions: spatial resolution of fabrication up to 200 μm with Ra up to 5 μm, transition zone between layers of different composition can be varied in a wide range starting from 10 μm.

Experimental and calculated results of the investigation of electromagnetic field distribution including its polarization characteristics in the vicinity of the structures with subwavelength sizes are presented. The experimental investigation was realized by aperture type scanning near field optical microscope, which operated in collection mode and provided both high spatial resolution and large scanning range. Shear force detection was used for the control of aperture to surface gap. Normal resolution, which allows us to image down to 0.3 nm height surface steps, was demonstrated for this gap control system. Theoretical computation of electromagnetic field distribution was realized by finite-difference time-domain (FDTD) method. Experimental three-dimensional maps of intensity and polarization distribution as a result of light diffraction at subwavelength aperture in metal screen, dielectric and metallized subwavelength cylinders were obtained. The qualitative difference between the orthogonal polarized component distributions near subwavelength aperture in aluminium screen was experimentally shown. The electromagnetic field concentration in the proximity of the dielectric nanocylinders was observed. This observation gives good fit with the results of FDTD computations. A spiral type electromagnetic field distribution pattern was experimentally observed in the proximity of metallized subwavelength cylinders, which is unexpected from both experimental and theoretical points of view.

An approach to the optical investigation of probes for scanning near-field optical microscopes (SNOM tips) and recognition of their near-field parameters by far-field measurements is considered. The comparison of approximate calculations of vector light field diffracted by a subwavelength aperture with more rigorous calculations of the light field passing through a tapered end of a SNOM tip is presented. A numerical iterative procedure of the SNOM tip aperture reconstruction by the analytical continuation of the emerging light Fourier spectrum is presented. The approach is based on the use of plane waves covering a wide range of spatial frequencies. The results of experimental measurements and far-field data treatment with the definition of a subwavelength aperture are discussed.

Nowadays the near-field optical probe (NOP) for SNOM (scanning near-field optical microscopy) is mainly produced from optical fibers. The laser technology of NOP manufacturing is based on the local fiber area heating and following force stretching up to brake. Therefore the experimental setup consists of an optical scheme and mechanical system which are due to provide the local source of heat on the fiber surface and a proper regime of force application. As the NOP's geometric parameters principally determine the SNOM efficiency and, on the other hand, they are fully dependent on the manufacturing conditions it is important to find the optimal setup solution. While studying already existing schemes, we are making an attempt to find such a solution by taking care of precise mechanics capable of symmetrical pulling performance and developing a non-standard optical scheme for determined local uniform illumination of the fiber.

A new spectral-domain interferometric method of measuring absolute distances is utilized when the effect of low dispersion in an interferometer is known and the spectral interference fringes are resolved over a wide spectral range. First, processing the recorded spectral interferograms by a phase-locked loop (PLL) method, which is a special simplified version of the general recurrence non-linear data processing method, the unmodulated spectrum, the spectral fringe visibility function and the unwrapped spectral fringe phase function are obtained. Then, knowing the dispersion relation for the material present in the interferometer, the material effective thickness is determined. Finally, the positions of the interferometer mirror are determined precisely by fitting the recorded spectral interferograms to the theoretical ones knowing all the mentioned spectral functions.

Modern approach to the optical investigation of optical systems of the highest precision is considered. Lack of classical interferometers is the necessity of presence for their schematics the reference optical element, so its accuracy is limited always. However for the testing of optical systems and elements of the best class the devices ensuring accuracy at a level 1/100 - 1/200 λ are necessary. It is on the order more exact than the traditional. As the alternative, the concept of the interferometer with diffracted reference wavefront [point diffraction (PDI) --interferometer] is offered. In this research the schematic of PDI-interferometer with basic front, common for working and observant branches, is developed. The errors are reduced. The flexibility and universality of an interferometer are achieved. The accuracy, simplicity and profitability are increased. The adjusting is simplified.

New phenomena of anisotropic light scattering, anisotropic Cherenkov third-harmonic generation, photoinduced birefringence and anisotropic reflection from femtosecond direct-write structure are reviewed. The phenomena and recent direct observation reveal the smallest embedded structures ever created by light and new mechanism of light-matter interaction.

We have observed self-guiding of a single femtosecond visible laser pulse in the bulk of transparent nonlinear media (SiO₂, KDP) and in the water. The dependence of filament length on laser pulse energy was measured. Continuous open-ended channels and frozen modifications of the matter were observed in transparent two-component condensed medium (thin glass plate placed in water).

Development of pulsed excitation techniques for high-pressure dielectric barrier discharges (DBD) has led to a short-pulsed, high-peak-power, spatially uniform source of UV7VUV radiation -- a preferred type of output for materials processing and many other applications. Results of such a Xe₂* DBD source at 172 nm for removing mountants from optical surfaces and for removing hydrocarbon contamination from optical and polymer surfaces are presented.

The precision machining of glass by laser ablation has been expanded with the short wavelength of the 157 nm of the F2 excimer laser. The high absorption of this wavelength in any optical glass, especially in UV-grade fused silica, offers a new approach to generate high quality surfaces, addressing also micro-optical components. In this paper, the machining of basic diffractive and refractive optical components and the required machining and process technology is presented. Applications that are addressed are cylindrical and rotational symmetrical micro lenses and diffractive optics like phase transmission grating and diffractive optical elements (DOEs). These optical surfaces have been machined into bulk material as well as on fiber end surfaces, to achieve compact (electro)-optical elements with high functionality and packaging density. The short wavelength of 157 nm used in the investigations require either vacuum or high purity inert gas environments. The influence of different ambient conditions is presented.

Studies of UV laser photolysis of Er organometallics (ErFOD) impregnated into porous Vycor glass in supercritical CO₂ was performed, aimed at developing a new approach to glass microstructuring. It was revealed that quantum yield of UV laser photolysis increases with laser intensity. Efficiency of ErFOD photodegradation for the XeCl laser irradiation is almost two orders of magnitude higher than that for KrF laser. The effect of light scattering in the porous glass on the focusing of laser beam was also revealed.

Kinetics of sintering of porous glass (further PG) plates of composition 96SiO₂ • 3.8 B₂O₃ • 0.2Na₂O (a pier. %) has been explored in these researches. The sintering was carried out under activity of CO₂-laser radiation. Wavelength of CO₂-laser (λ = 10.6 μm) lies in the range of majority absorption of a silica glass. Definition of making requirements of thin sintered layer with the greatest possible radiuses of curvature was the purpose of researches. Also in researches, the purpose to receive the positive microoptical device (further MOD) from the initial negative MOD has been put. Researches have been made at change of action time (further τ) and a stationary value of a power density of radiation (further q), and also at change q and constant τ.

A new method for fabrication of optical microspheres with the use of a CW CO₂ laser is reported. Conventional method for fabrication of microspheres includes grinding and polishing processes which is not only time consuming, but also difficult of getting optical spheres with diameter less than 500 μm. It will be demonstrated that the laser method is very simple and capable of producing a wide range of optical spheres with diameter of several millimeters down to 10 micrometers or even less, and a wide range of materials can be used (glasses, porous glasses, glass-like ceramics...). Some applications of microspheres produced by the laser method are discussed.

The new principals of organization of parallel input-output of the optical information in the personal computer from the fiber-optical measuring lines are considered. The device has block structure and has two modes of operation: calibration mode of operation and work mode of operation. In the calibration mode of operation computing system is adaptation to condition of the solution problem of reconstruction information about parameters of monitoring physical fields. In the work mode of operation the device implements the adaptive processing of incoming optical radiation.

Surface treatment of metals and other materials is studied using sub-picosecond laser pulses at 248 nm. The advantage of the combination of femtosecond pulse durations with ultraviolet wavelengths is pointed out. Full utilization of the specific pulse parameters for nano-scale material processing is demonstrated. Imaging techniques combined with diffractive optical elements are exploited for the generation of two dimensional periodic structures. Superior quality and feature sizes below 100 nm are achieved. The ultra-short pulse UV laser system applied for surface texturing comprises a Ti:Sapphire front-end system and a specially developed excimer amplifier module generating 300 fs pulses at 248 nm with an average power of ~10 W. The excimer module operating at 300 Hz together with a newly introduced beam smoothing technique allows high precision texturing of large surfaces opening up new possibilities in industrial applications.

Photo-lithographical laser ablation was demonstrated by laser ablation using a femtosecond laser system with a lithographic optical system. Among them, laser beam passed through a mask and the pattern was imaged on the film by a pair of convex lenses. As a result, the film was lithographically ablated, and micron-sized patterns were generated in a single shot. Fringes were generated outside the ablated patterns with defocusing or larger laser fluence. The resolution of generation was 13 μm, and the narrowest width of a generated line was about 4 μm. In addition, transmission gratings were used instead of a mask, and nano-sized periodic structures were generated.

As an investigation of the process of laser-induced forward transfer (LIFT), the behaviors of atoms, thermally radiating hot droplets and comparatively cold droplets were observed by two-dimensional laser-induced fluorescence (2D-LIF), laser light scattering (LLS) and thermal radiation. The observations were done with different parameters such as ablation laser energy, film thickness and gas pressure. The condition for the deposition of smaller film was guided. On the other hand, as an application, material transfer by LIFT was experimented. Rhodamine 610 laser dye film, which was deposited on silica substrate by LIFT, emitted fluorescence with an excitation by a second harmonic wave of the Nd:YAG laser. Experimental observations show that the fluorescence intensity of the deposited film was dependent on the LIFT process condition. The optimum condition was attained with a 50 nm thickness of the base gold film and 49 mJ/cm² of the ablation laser fluence and in vacuum condition.

Carbonyls of transition-metals Mo(CO)₆, Fe(CO)₅ were used for laser chemical vapor deposition (LCVD) of elements under the action of KrF laser radiation (λ_L = 248 nm) and Ar⁺ laser radiation (λ_L = 488 nm) on SiO₂ and Si substrate surface. Rate constants of heterogeneous reaction of Mo and Fe atoms deposition were calculated while irradiating SiO₂ and Si substrate surface. Element analysis of deposited films made with energy dispersive X-ray spectroscopy (EDXS) and Auger electron spectroscopy (AES) reflects that atomic concentration of C atoms was not equal to atomic concentration of O atoms owing to the existence of dissociative channel of adsorbed CO molecules on MO and Fe surface. From these data and average surface temperature, dissociation constants of CO molecules and C-O binding energies of adsorbed CO molecules were calculated.

The possibility of the pulse laser radiation treatment of thin metal films on glass substrates has been studied experimentally. On the glass substrates with sprayed coating the diffraction structures were obtained due to the selective evaporation of metal at the interference of the powerful pulse laser radiation. The experiments were conducted using copper, aluminum films and films from titanium oxides. The thickness of the films on the glass substrates was 0.1 ÷ 0.12 μm. The regimes normally used during the film treatment with a laser beam were as follows: the wavelength was 1.06 μm, the pulse duration was 10 ns, and the enegy density of the beam was 10 mJ/mm². To obtain an interference pattern on the treated surface the beam of the coherent radiation was preliminary split into two. In dependence on the convergence angle of the interference beams, the diffraction gratings had the lattice spacing in the range of 1 ÷ 6 μm. They were used to produce diffraction lenses. These lenses are a plane device with a ring-shape zone of concentric grating grooves capable to focus a certain part of incident radiation. In dependence on the wavelength, the radiation is collected on the optic axis at different distances from the diffraction lens. This fact makes it possible to use the lens in production of a simple monochromator. The structure of the diffraction gratings obtained has been studied, and their main characteristics and main spheres of their application have been determined.

Special features of the interaction of the powerful pulse laser radiation with films from graphite-like carbon material (layers of oriented carbon nano-tubes and plate-like graphite crystallites with the size of the nanometer order) were studied experimentally. After irradiation with 5 - 10 laser pulses for 22 ns on the wavelength of 1064 nm at a power density of 10 - 30 MW/cm², the appearance of lengthy structural formations on the rough surface of the carbon film has been observed. The formations have a preferred direction perpendicular to the plane of the linear polarization of laser radiation, which is normal incident on the film surface. It has been shown that the carbon film treatment with circularly polarized laser radiation does not give rise to the appearance of oriented structural formations. The investigation of special features of the diffuse-scattered light from the surfaces of carbon films in the initial state and carbon films irradiated with laser was carried out. It has been established that powerful laser radiation gives rise to the appearance of a significant anisotropy in the indicatrix of the diffuse-scattered light from the surfaces of the irradiated films under study. The model was proposed, which explained the experimental results by anisotropic evaporation of the graphite-like carbon material occurring due to the essential polarization dependence of the absorption and reflection factors of light at large angles of incidence on an absorbing rough surface.

The peculiarities of laser sintering of single-component powders as a semisolid processing method are considered. special attention is paid to study of behavior of powder under laser sintering as a specific semisolid medium including aspects such as laser radiation-powder interaction, inter-particle contacts' formation, rearrangement of particles.

The article deals with phase transformation in aluminum-magnesium alloys during high speed cooling after the laser action. The intermetallic precipitation growing is calculated with the reaction-diffusion model. The “shooting” method was used for analytical solution of equation for grow of spherical inclusion. Mutual influence in ensemble of precipitation is taken into account as changes of admixture concentration on “infinity”. Unification of model of precipitation ensemble development with the stochastic model of precipitation engendering and self-consistent model of laser welding allow to calculate a size distribution of inclusions in heat effected zone.

The article devoted to modeling of influence of thermo-capillary convection on heat transfer in melting pool during CW laser welding. An approximation of potential flow with boundary layers was used for solution of hydrodynamic problem in melting pool. A hydrodynamic problem was formulated in terms of current function. To determine a value of melt velocity circulation a condition of equality of mechanical powers of driving force (Marangoni tension) and braking force (viscous tension in boundary layer) was used. Calculations show that Marangoni convection increase an upper part and diminish a bottom part of melt pool.

The set of original pyrometers and the special diagnostic CCD-camera were applied for monitoring of Nd:YAG laser cladding (Pulsed-Periodic and Continuous Wave) with coaxial powder injection and on-line measurement of cladded layer temperature. The experiments were carried out in course of elaboration of wear resistant coatings using various powder blends (WC-Co, CuSn, Mo, Stellite grade 12, etc.) applying variation of different process parameters: laser power, cladding velocity, powder feeding rate, etc. Surface temperature distribution to the cladding seam and the overall temperature mapping were registered. The CCD-camera based diagnostic tool was applied for: (1) monitoring of flux of hot particles and its instability; (2) measurement of particle-in-flight size and velocity; (3) monitoring of particle collision with the clad in the interaction zone.

Relatively new method of producing 3D objects with Functionally Graded Material (FGM) structure is realized by coaxial powder injection with variable composition into the zone of laser beam action. The desired 3-dimensional material distribution is realized by repetitive deposition process. Theoretical analysis and experimental results show essential role of radiation mode and powder granularity as optimization parameters. Applied laser sources are continuous wave Nd:YAG(HAAS 2006D, 2kW), pulse-periodic Nd:YAG(HAAS HL304P, avg. power 300 W), quazi-cw CO₂ (Rofin-Sinar, 300 W). Among applied materials are nanostructured WC/Co, CuSn, Stainless steel 316L, 430L, Co-base alloy, nanostructured FeCu, etc. The originality of obtained results is that different gradient types are produced "in situ" and combined within one sample: smooth, sharp or multilayered gradients. The number of samples is produced and examined with metallographical and SEM analysis. The minimal spatial gradient resolution (transition zone between two different materials) is starting from 10 microns and can be varied in a wide range; the surface roughness depends from powder granularity, best value of Ra is about 5 μm, microhardness of differet zones of samples is varied from 120 to 450 HV. The achieved geometry spatial resolution is 200 μm.

The new approach to laser powder sintering and 3D-forming based on Bessel laser beams is presented. The results of calculations of powder stream impact on Bessel beam parameters and powder particles and base heating is displayed.

With the established technique of laser in precision micromaterial processing, the fabrication of cardiovascular metallic stent with high quality has now become feasible. From the actual CAD design and FEM analysis of the stent fabrication, the need for the surface modification properties becomes essential in enduring its extended life duration. This paper describes the current status as well as fabrication of such metallic stent of length 20 mm and dia. 2.1 mm with an annular tube thickness of 0.2 mm, by using the short pulse Nd-YAG laser. Fine structures with slit width of 0.1 mm and pitch better than 0.2 mm are created with sharpness and low roughness in the cut surface. Some features on improving the surface characteristics of the cut surfaces of the stent, excimer laser coronary angioplasty and ultrasound ablation of plaque as well as a few techniques on preventing restenosis are well documented.

Micropipettes become the important tools in many areas of science and technologies: in biomedical technology, in scanning near-field optical microscopy, in nanolithography etc. In this paper the research results of laser-assisted forming of micropipettes are presented. The main behaviors of micropipette shaping under laser heating are investigated. The influences of power density, of stretching force on the geometrical shape of micropipettes are studied. The mathematical model of process is also considered.

Environmental science is concerned about the content of dissolved heavy metals in coastal tidal waters. Fluorescence spectroscopy methods do offer a chance for the detection of dissolved chromium. Due to strong quenching processes in liquids, optical emission spectroscopy often lacks sensitivity. In this study we intended to use subsequent Nd:YAG Q-switched laser pulses to create a plasma directly in front of an optical fiber tip. The plasma emits light at characteristic chromium wavelengths. The emitted fluorescence was recorded using an optical multi-channel analyzer.

A bleaching effect of a strong absorbing fluid by a short laser pulse is investigated for the layer depth of the order of the absorption length under assumption of the linear relation between the fluid density and absorption coefficient. Gaussian and ring perpendicular intensity distributions of beams are considered. Space and time evolution of the basic parameters of the interacting matter and radiation are calculated -- density, temperature, pressure, specific inner energy, fluid velocity, radiation intensity. A satisfactory agreement is found for the theoretical and experimental transparency function dependence on the pulse energy.

Here we discuss the results of the experiments performed using the Prague Asterix Laser System (PALS) of wavelength 0.44 μm (3ω of Iodine laser) and energy ≈ 250 J in 450 ps (FWHM). Two sets of experiments were carried out, firstly, generation of high quality shocks which were steady in time and uniform in space using Phase Zone Plates (PZP), to establish the scaling laws of shock pressure Vs. laser intensity for aluminum foil target of thickness 8 μm. Our results show a good agreement with the delocalized laser absorption model. Secondly, measurements of the Equation of State of carbon compressed by shocks at megabars of pressure have been realized. Equation of State were obtained for carbon using the impedance mismatch technique. Step targets allowed the simultaneous measurements of shock velocity in two different materials. Aluminum was used as a reference material and relative EOS data for carbon have been obtained up to ≈ 14 Mbar pressure.

Temporal evolution of laser generated cavitation bubbles and shock waves were studied. Q-switched Nd-Yag laser pulses at 1064 nm are focused into the liquid. An Imager 3 CCD camera with multi exposure mode allows recording of 10 images with minimal exposure delay of 100 ns and minimal exposure time of 100 ns. Illumination is provided by xenon flash lamp for single exposure (shock wave recording) and by halogen lamp for multi exposure mode (bubble recording). Distilled water and a retrograde fluid, isooctane, have been under investigation to identify the differences in the cavitation process and shock wave propagation. The calculation of the shock wave velocities in water and isooctane are based on image recording at constant exposure time of 100 ns and using laser differential interferometry. Strong differences of bubble oscillation were observed in water and isooctane. Gilmore's model is used for numerical simulation of bubble dynamics.

The possible manifestations of the thermodynamical instability (explosive vaporization) are discussed for different regimes of laser heating of the target. It is shown that repeated explosive vaporization regime can be realized during nanosecond laser pulses provided that nucleation time τ < 10^-10s. This regime can be observed if the surface pressure is lower than the critical pressure P_c of the liquid-vapor phase transition. The laser vaporization front instabilities are investigated for the steady state vaporization regime of absorbing condensed matter. The results of the numerical analysis of the dispersion equation are presented for various values of the target absorption coefficient α and different Mach number M ≤ 1 in the vapor flow. In several cases of bulk absorption (α ≤ 10⁴ cm^-1) the instability increment maximum γ_max is of the order of 10⁹s^-1 and the corresponding wavelength λ_max ≥ 0.3 μm. The dependence of these results and vaporization dynamics on the sticking (condensation) coefficient in vaporization boundary conditions is also analyzed.

The plasma-controlled evaporation of the Al target induced by the laser pulse with intensity of 8 x 10⁸ W/cm² and wavelength of 1.06 μm is analyzed with account for the two-dimensional effects. The self consistent model is applied, consisting of the heat transfer equation in condensed medium, the system of radiation gas dynamics in evaporated substance, and the Knudsen layer model at the two media boundary. It is established that the phase transition of the target surface is controlled by the two factors: the surface temperature that depends on the transmitted radiation intensity and the plasma pressure, governed by the expansion regime. The process comes through three characteristics stages -- the sonic evaporation at the beginning, the condensation during the period of plasma formation and initial expansion and, finally, the recommence of evaporation in subsonic regime after the partial brightening of the plasma. During the subsonic evaporation stage the vapor flow and the mass removal rate is much higher near the beam boundaries than in the center due to smaller plasma counter-pressure. The vapor plasma pattern is characterized by the dense hot zone near the surface where the deposition of laser energy occurs, and rapid decrease of density outside the zone due to three-dimensional expansion. The application of the laser beam of smaller radius at the same intensity leads to the formation of more rarefied and more transparent plasma, that allows to improve the mass removal efficiency.