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A binary subwavelength four-zone transmission grating micropolarizer for conversion of a linearly polarized incident laser beam into a azimuthally polarized beam with a phase shift of π at diametrically opposite points of the beam was synthesized and characterized. The proposed micropolarizer consists of four sectors with angles -60°, 60°, -60° and 60° with the y-axis. The micropolarizer has a period 230 nm, width of step 138 nm, and width of groove 92 nm. The micropolarizer was designed for wavelength 633 nm and was manufactured in silicon (refractive index n = 3.87 – 0.016 i ) spattered on a glass substrate. The size of micropolarizer was equal to 100×100 μm, and the microrelief height was equal to 130 nm. The performance of designed micropolarizer was simulated using FDTD-method. A linearly polarized plane wave of wavelength 633 nm was assumed to illuminate the polarizer at the normal incidence. The mesh of the FDTD method had a λ/30 step. The field distribution at a significant distance from the polarizer was calculated using the Rayleigh-Sommerfeld integral, with the FDTD-aided complex amplitude calculated 100-nm away from the surface taken as an initial field guess. It was shown that the obtained beam focused by Fresnel zone plate with focal length 532 nm produces focal spot with diameters FWHM x = 0.42λ and FWHM y = 0.81λ. Focal spot formed only by the transverse component of electric field has diameters FWHM x = 0.42λ and FWHM y = 0.59λ.

We discuss a four-Sector transmission Polarization Converter that enables the conversion of linearly polarized incident light into an azimuthally polarized beam. The resulting azimuthally polarized beam is characterized by a phase shift of π between the diametrically opposite beam points. Using scanning near-field optical microscope we experimentally show that by placing a Fresnel zone plate of focus 532 nm behind the four-sector micropolarizer, light can be focused into a subwavelength focal spot with smaller and larger sizes measuring FWHM = 0.46λ and FWHM = 0.57λ Numerically obtained focal spot of the transverse E-field component, which is measured by our scanning near-field optical microscope, has diameters FWHM x = 0.42λ and FWHM y = 0.59λ.

In this work the single surface plasmon-polariton was obtained by using frequency-dependent finite difference time domain method for the radial polarized and vortex beams at 532 nm, which were propagating through the silver nanoring on substrate from silica glass, placed in an aqueous medium. The height and width of device were equal to 20 nm and 215 nm respectively. The intensity of surface plasmon-polariton was four times higher and three times higher the intensity of the incident radiation for case of conventional and vortex beams respectively. The full width at half maximum of the nanojet was near 160 nm for each cases. The presented design can be used for manufacturing of highly integrated optical devices and circuits used in high-speed communication applications. The results also can be used to design devices that allow capturing and moving the particles in water or other biofluidics.

The aim of this report is detection of model compound, rhodamine 6G (R6G), in blood and urine samples using surfaceenhanced Raman spectroscopy (SERS) as a detection tool and liquid-liquid extraction (LLE) for improving quality of SERS analysis (SERS-LLE combination). SERS substrate is a plasmonic nanomaterial which possesses drastic increasing of Raman spectrum intensity (10 6 ‒10 8 ) of any molecule adsorbed onto its surface. Here we used citrate stabilized silver nanoparticles as SERS substrate and synthesized them applying wet chemical approach. Before SERS measurements, blood and urine samples were artificially contaminated with R6G using 50 and 500 ng/mL concentrations for both samples. In order to reduce detectable concentrations of R6G and improve signal-to-noise ratio, we applied LLE which allows us to separate R6G from the matrix mixture and increase the analyte concentration. Four different LLE protocols were used and the most efficient one was found. Obtained results showed usefulness of SERS-LLE combination for chemical analysis of body fluids with level of detectable concentration down to tens ng/mL.

The aim of this work was the fabrication of nanolabels (SERS-nanotags) which are used for chemical analysis by means of surface-enhanced Raman spectroscopy (SERS), and registration of their SERS spectra inside photonic crystal fibers (PCF). The SERS nanotags fabrication included synthesis of silver nanoparticles with subsequent deposition of Raman active layer (thiol-group contained aromatic compound) and protecting layer composed of silica shell. Finally, SERS spectra of the SERS nanotags were registered inside PCF in order to determine the value of fiber-enhancement of the Raman signal and to estimate analytical potential of this combination.

Cutting and drilling of transparent materials using short pulsed laser systems are important industrial production processes. Applications ranging from sapphire cutting, hardened glass processing, and flat panel display cutting, to diamond processing are possible. The ablation process using a Gaussian laser beam incident on the topside of a sample with several parallel overlapping lines leads to a V-shaped structured groove. This limits the structuring depth for a given kerf width. The unique possibility for transparent materials to start the ablation process from the backside of the sample is a well-known strategy to improve the aspect ratio of the ablated features. This work compares the achievable groove depth depending on the kerf width for front-side and back-side ablation and presents the best relation between the kerf width and number of overscans. Additionally, the influence of the number of pulses in one burst train on the ablation efficiency is investigated. The experiments were carried out using Spirit HE laser from Spectra-Physics, with the features of adjustable pulse duration from 16 W ( at 1040 nm wavelength).

Non-ablative, femtosecond laser process ClearShapeTM from Spectra-Physics for cutting transparent, brittle materials is based on producing a micron-sized material modification track with well-defined geometry. Although this process allows cutting by using relatively low average power of 4 W, for further improvement of the process we have studied how to make an efficient usage of higher average power and higher pulse energy available from an industrial femtosecond laser systems. In this paper, we give an overview of the machining results obtained using femtosecond Spirit HE. The high average power (

Electrostatically actuated MEMS switch with the resistive contact is presented. Design of the switch includes the active contact breaking mechanism, which allows to detach the beam from the signal electrode in case of sticking. The mechanism is realized by the presence of two driving electrodes under the beam. The switch is fabricated by the surface micromachining. Finite element simulation and experimental investigation of the switch in a cold regime are performed.

The paper describes a method of electro-optical modulation for broadband radiation. Specifically, an analysis was undertaken of a broadband spectrum conversion for an infrared short-wave region with an optical spectral range (i.e., 0.74–2.5 μm. The effects of crystals’ geometry and the width of spectral ranges on the modulation depth of radiation were also considered. The proposed scheme allowed the depth of broadband radiation (not less than 80 percent with a change in crystal temperature) to be modulated and, due to the selected orientation of the optical elements, did not deteriorate the modulator’s characteristics.

We have numerically and experimentally investigated subwavelength grating-polarizer that transform linearly polarized light of wavelength 633 nm into azimuthally polarized beam with a phase shift π at diametrically opposite points of the beam. This beam focused by Fresnel zone plate with focal length 532 nm produces focal spot with diameters equal to 0.42 and 0.81 of wavelength.

The conversion of broadband IR radiation when the noncritical phase matching condition is fulfilled in lithium niobate (LiNbO3) single crystals with stoichiometric (R = Li/Nb = 1) and congruent (R = 0.946) compositions, as well as in congruent single crystals doped with zinc has been investigated. It is shown that the spectrum parameters of converted radiation, such as the conversion efficiency, spectral width and position of maximum, depend on the ordering degree of structural units of the cation sublattice along the polar axis of crystal.

We have considered some special cases the interaction of optical radiation and photorefractive crystals. We gave special attention to the impact of the characteristics of optical radiation, the intensity, frequency and polarization of the wavefront onto the features of the large-scale and small-scale optical defects forming due to the photorefractive effect in crystals. We registered forming of the small-scale optical defects via observing of the photoinduced light scattering in photorefractive lithium niobate crystals. And we registered forming of the large-scale optical defects in lithium niobate crystals by the polarizers system. Lithium niobate crystals have significant electro-optical and photorefractive properties. They are convenient model for studying how the light waves propagate through the photorefractive crystals. The article discusses the results of the experiments.

In this work the "central" surface plasmon-polariton was obtained by using frequency dependent finite difference timedomain method for the TM-polarized light at 532 nm, which was propagating through the silver nano-strip, placed in an aqueous medium. The height and width of nano-strip was equal to 20 nm and 215 nm respectively. The intensity of surface plasmon-polariton was four times higher the intensity of the incident radiation. The full width at half maximum of the nanojet was 138 nm. The "central" surface plasmon-polariton was obtained by using frequency dependent finite difference time-domain method for the radial-polarized light at 532 nm, which was propagating through the silver nanocircle, placed on a silica glass in an aqueous medium. The height and width of nano-strip was also equal to 20 nm and 215 nm respectively. The intensity of surface plasmon-polariton was four times higher the intensity of the incident radiation. The full width at half maximum of the nanojet was 158 nm. The results can be used to design devices that allow capturing and moving the particles in water or other biofluidics.

Fluorescent spectroscopy (FS) is becoming more widely used in chemistry, biology, in various fields of medical technology and medicine in general. Many purulent wounds, burns and other destructive inflammatory processes are accompanied by changes in the fluorescent activity of the tissues, which occurs due to a misbalance in accumulation of natural fluorophores: FAD, NADH, lipofuscin, porphyrins, structural proteins, etc. The study of redox ratio (RR), characterizing the metabolic processes, is important in the assessment of the metabolic activity ofmicrocirculatory-tissue systems (MTS). However, one of the big problems of the FS method is still the correct interpretation of the data and the development of practical methods for its application in clinical medicine. To solve this problem and create new diagnostic criteria, we propose to evaluate the adaptive capacity of MTS using indicators of links between nutritive blood flow and redox ratio during a physiological rest and functional load (occlusion test). As is known, these parameters (RR and nutritive blood flow) characterize the metabolic activity of tissues.We have performedan experimental study of the relationship between the RR, defined by FS, and nutritive blood flow, defined by the methods of laser Doppler flowmetry. Preliminary results in the study of a complex approach to diagnosis of the state of biological tissue were obtained. A positive relationship between the nutritive blood flow in the microcirculatory channel and RR of skin tissue is observed.The speed of change of metabolism in the phase of occlusion and reperfusion and duration of phase of recovery may be the criteria for adaptive capabilities of MTS, which has practical significance for physiology and medicine.

A experiments were performed in the shelf zone of the Black Sea in 2015 to study variability of the current fields and other characteristics of sea bulk, wind waves, and the near-surface atmospheric layer. Region with the secluded underwater hill streamlined with currents was selected. Measurements were carried out from the onboard of vessels on move and in drift by optical, radar, acoustic equipment, and STD probe. The complex different structure of waters, which was formed under the influence of shelf waters and water of the open sea interaction, was observed during the experiment. The analysis of measurements in the water column showed that that the flow around underwater elevation forms the hydro-physical disturbances of marine environment. Maximum flow observed above the slopes of underwater elevation and reach 50 cm/s. Wind speed varied from 0 to 10 m/s. On radar panoramas in the region of underwater elevation is observed the appearance of the wave structure, different from the background wind waves. This anomaly on the sea surface is connected with non-uniform current in the neighborhood underwater elevation.

Laser processing of optically transparent or semi-transparent, brittle materials is finding wide use in various manufacturing sectors. For example, in consumer electronic devices such as smartphones or tablets, cover glass needs to be cut precisely in various shapes. The unique advantage of material processing with femtosecond lasers is efficient, fast and localized energy deposition in nearly all types of solid materials. When an ultra-short laser pulse is focused inside glass, only the localized region in the neighborhood of the focal volume absorbs laser energy by nonlinear optical absorption. Therefore, the processing volume is strongly defined, while the rest of the target stays unaffected. Thus ultra-short pulse lasers allow cutting of the chemically strengthened glasses such as Corning Gorilla glass without cracking. Non-ablative cutting of transparent, brittle materials, using the newly developed femtosecond process ClearShapeTM from Spectra-Physics, is based on producing a micron-sized material modification track with well-defined geometry inside. The key point for development of the process is to understand the induced modification by a single femtosecond laser shot. In this paper, pump-probe microscopy techniques have been applied to study the defect formation inside of transparent materials, namely soda-lime glass samples, on a time scale between one nanosecond to several tens of microseconds. The observed effects include acoustic wave propagation as well as mechanical stress formation in the bulk of the glass. Besides better understanding of underlying physical mechanisms, our experimental observations have enabled us to find optimal process parameters for the glass cutting application and lead to better quality and speed for the ClearShapeTM process.

An automatic technique for processing holograms of particles present in water is proposed. Its applications to determine particle concentration and their size distribution are illustrated with examples. The method is validated using waterborne air bubbles and particles settling in water. The use of video based on holographic data is considered for dynamic investigation of these particles. This video consists of sequences of holographic images of particles and the concentration and particle size distribution is studied in dynamics.

A experimental laboratory study of the effect of a horizontally inhomogeneous current on breaking statistics of wind waves was carried out. Were creating a current having the same direction as wind waves with positive and negative gradients and a current of the counter direction with a negative gradient. The wind speed varied from 10.4 to 20.1 m/s based on a standard height of 10 m. The maximum current velocity near the surface was 27 cm/s. The maximum current gradient was equal to 0.09 1/s. The codirected current reduces the wind wave amplitude for all wind speeds, while the frequency of the spectral density maximum of wind waves remains the same. The frequency of the recorded by radar wind-wave breaking also decreases for positive, negative, and zero gradients. In the case of counter directions, for light winds in the presence of a current the wind wave amplitude reduces, the wind wave spectrum displaces in the direction of lower frequencies. At higher wind speeds, there were neither differences in the surface wave spectra in the presence and absence of a current, however, an increase in the frequency of the recorded by radar wind-wave breaking is observed. These laboratory investigations are carried out in the interests of the remote diagnostics methods development of inhomogeneous currents at higher wind speeds.

A compact, lightweight multichannel laser and heterodyne spectrometer is under development for the ExoMars-2018 landng platform. The instrument is aimed at sensitive measurements of the ambient atmosphere composition, isotopic ratios and structure, both in situ and on the open path by direct Sun observations.

New educational kit and methodological instructions are presented in the paper. Methodological approaches and the kit design are improved and extended on the base of 10 years experience of the use of previous version of equipment. Basic approaches are the following: modular structure of the equipment with multifunctional blocks which are easily replaced; simplicity and unity of training equipment; diversity of light sources; possibility to rearrange the equipment and techniques both for universities and for high school; modified optical schemes for some experiments.The set of equipment includes: compact desk holographic installation, Hartle device, focal monochromator on the base of holographic lens, optical bench, prisms, lenses, gratings, collimator, several light sources (laser, LEDs, lamp), etc. Methodological instructions provided with this set include the list of demonstrations and laboratory works as well as links between various experiments and phenomena. Methodological instructions give recommendations for more than 50 demonstrations and practical works in various domains: light diffraction, interference of light, holography, geometric optics, Fourier optics, polarization effects, optics of spectrums, fiber optics, as well as a combination of the effects.1. Intro duction.In comparison with the previous version of the kit [1], this equipment (UMOG-3) is more functional and provides more demonstrations and laboratory works. At the same time, the main principles of equipmentdesign are the same – modular construction with the possibility to combine, rearrange and supplement the main blocks and elements; absence of complicated, precision and expensive units.The kit allows realizing the number of demonstrations, including the following:- edge diffraction;- slit diffraction;- hole diffraction;- Young experiment;- diffraction on a periodic structure;- wedge interference;- Newton rings;- Lloyd mirror;- polarization effects;- Fourier-optics;- phase contrast;- observation of paths of reflected and refracted rays;- total internal reflection;- light propagation through inhomogeneous mediums;- optical heterogeneity visualization by shadow method;- modeling of the light propagation through the fiber;- demonstration of aberrations (spherical aberration, coma, astigmatism, distortion);- white light polychromatic structure.The kit allows realizing the number of training labs, including the following:- recording of Denisyuk holograms;- recording of double-exposed holographicinterferogram;- measuring of plate deformation by holographicinterferometrymethod;- measuring of distance between 2 holes on Young pattern;- measuring of diffraction grating period;- measuring of light source wavelength;- measuring of lens focal length;- measuring of wedging of plane-parallel plate;- radius of curvature measuring of plano-convex lens surface;- Fourier-optics experiments;- measuring of reflection and refraction angles;- Snell law studying;- Brewster angle measuring;- measuring of prism internal reflectance angle and refractive index;- Fresnel formulae;- Malus law studying;- measuring of diffraction grating efficiency;- evaluation of relief of hologram profile;- evaluation of holographic lens parameters;- measuring of the fiber loss;- spectrum measuring.

It was numerically and experimentally shown that square-profile microsteps with width of 0.4 μm, 0.5 μm, 0.6 μm, 0.8 μm and height of 500 nm illuminated by linearly polarized laser light with wavelength λ = 633 nm formed near its’ surface photonic nanojets with intensity that is 6 times higher than the intensity of incident light. Experimentally measured diameters of photonic nanojets were equal to 0.44λ, 0.43λ, 0.39λ and 0.47λ (less than the diffraction limit 0.51λ).

We consider superposition of two paraxial two-dimensional half Pearcey laser beams. By the beam propagation method (BPM), we study the beam intensity distribution in focal plane. For superposition with zero phase delay between the beams, the simulation showed that focal spot has a width of 0.36 free-space wavelengths, while superposition with phase delay of π allows obtaining two focal spots with a width of 0.42 free-space wavelengths.

Binary diffraction optical element was designed for polarization conversion from linear to radial. A grating period was equal to 400 nm, a relief height was equal to 110 nm. Simulation by FDTD method and Rayleight-Zommerfeld integral shown that there are radial polarized light beam in the far field with smooth angle dependence on the beam circle observation position. It was shown experimentally, that a gaussian laser beam with wavelength of 633 nm reflected from the polarization conversion plate contain a radially polarized light.

We study a non-paraxial family of nondiffracting laser beams whose complex amplitude is proportional to an n -th order Lommel function of two variables. These beams are referred to as Lommel modes. We also study finite-energy paraxial Lommel-Gaussian beams with their complex amplitude being proportional to the Lommel function and to the amplitude of the Gaussian beam. Explicit analytical relations for orbital angular momentum of the Lommel modes and Lommel-Gaussian beams have been derived. Asymmetry of the Lommel modes depends on a complex parameter с . Besides, with the modulus of the с parameter increasing from 0 to 1, the orbital angular momentum of the Lommel modes increases from a finite value proportional to the topological charge n to infinity. The orbital angular momentum of the Lommel modes undergoes continuous variations, in contrast to its discrete changes in the Bessel modes. Simulation by the beam propagation method showed that in initial plane the transverse intensity distribution of the Lommel-Gaussian beam contains a light ellipse with two bright spots. During propagation, these spots rotate by an angle, close to 90 degrees, at a much smaller distance than the Rayleigh range.

Since their introduction in 1986, stents have transformed the treatment of coronary heart disease and other arterial occlusions. Today, millions of stents are implanted worldwide each year to treat various vascular and endovascular diseases caused by the narrowing or blockage of blood vessels. Nearly all commercially available stents are made from metals. Theses stents remain in the vessels permanently after implantation and are prone to cause serious medical complications in many cases. One potential solution to avoid such complications is to use stents made out of bioabsorbable materials. Bio-absorbable stents dissolves in the human body after serving their purpose. However, machining of bio-absorbable material is a challenging task. In this paper the influence of the laser process parameters on the efficiency and quality of the machining of bio-absorbable materials using Spirit® femtosecond laser system from Spectra-Physics is presented.

Diseases of urinary bladder are a common healthcare problem world over. Diagnostic precision and predicting response to treatment are major issues. This study aims to create an optical cross-sectionional model of a bladder, capable of visually representing the passage of photons through the tissue layers. The absorption, transmission and reflectance data, along with the derived transmission coefficients (of scattering and absorption) were obtained from literature analysis and were used in the creation of a “generic” cross-section optical property model simulating the passage of thousands of photons through the tissue at different wavelengths. Fluorescence spectra of diagnostically relevant biomarkers excited by the UV and blue wavelengths were modelled on the basis of the Monte-Carlo method. Further to this, fluorescence data gathered by the “LAKK-M” system from pig bladders was applied to the model for a specific representation of the photon passage through the tissues. The ultimate goal of this study is to employ this model to simulate the effects of different laser wavelength and energy inputs to bladder tissue and to determine the effectiveness of potential photonics based devices for the diagnosis of bladder pathologies. The model will aid in observing differences between healthy and pathological bladder tissues registered by photonics based devices.

MEMS switch with the electrostatic actuation and the resistive contact was fabricated using surface micromachining. The movable electrode of the switch was the three-layer metallic cantilever having nanoscale thickness and high lengthto- thickness ratio. Low stiffness of the cantilever allowed to approach relatively low values of the actuation voltage. The theoretical analysis and experimental study of the switching characteristics was performed.

At present time radar methods of the seas and oceans diagnostics are actively developing. Using of the radar stations based on satellites and planes allows to receive information on a sea surface and a atmosphere near-surface layer with coverage of big water surface areas independently of day time. The developed methods of satellite radio images processing can be applied to marine radar stations. In Institute of Applied Physics RAS works on sea surface diagnostics systems development on the basis of standard marine radar are actively conducted. Despite smaller coverage of the territory in comparison with satellite data, marine radar have possibility to record spatially temporary radar images and to receive information on a surrounding situation quickly. This work deals with results of the researches which were conducted within the international expedition in the Atlantic Ocean in the autumn of 2012 on a route Rotterdam (Netherlands) – Ushuaya (Argentina) – Antarctica — Ushuaya. During this expedition a complex measurements of a sea surface, a atmosphere near-surface layer parameters and subsurface currents in the wide range of hydroweather conditions, including the storm were carried out. The system developed in IAP RAS on the basis of a marine radar ICOM MR-1200RII and the ADC (Analog Digital Converter) block for data recording on the personal computer was used. Display of a non-uniform near-surface current on sea surface radar images in storm conditions is shown. By means of the high-speed anemometer and meteorological station the measurements of the atmosphere parameters were carried out. Comparison of the anemometer data with calculated from radar images is carried out. Dependence of radar cross section from wind speed in the wide range of wind speeds, including storm conditions is investigated. Possibility of marine radar using for surface waves intensity and ice situation estimates also as icebergs detection is shown.

In this study we tested ns-laser and an atomic layer deposition (ALD) for polishing and coating CNC-machined aluminum freeform mirrors that are used in a compact multipoint fiber optical probe. Two types of ALD coatings, aluminum oxide and silicon dioxide were tested. The surface roughness of mirrors was analyzed prior to and after nanosecond-laser polishing and coating them on a Beneq TFS 200 ALD device. The freeform aluminum mirrors with and without coatings were then measured with optical profiler. The results show that improvement in the surface roughness can be seen with ns-laser polished and ALD coated aluminum surfaces.

A structural health monitoring system based on optical sensors has been developed and installed on the indoor soccer arena "Zarya" in Novosibirsk. The system integrates 119 fiber optic sensors: 85 strain, 32 temperature and 2 displacement sensors. In addition, total station is used for measuring displacement in 45 control points. All of the constituents of the supporting structure are subjects for monitoring: long-span frames with under floor ties, connections, purlins and foundation.

Multi-functional laser non-invasive diagnostic systems, such as “LAKK-M”, allow the study of a number of microcirculatory parameters, including blood microcirculatory index (Im) (by laser Doppler flowmetry, LDF) and oxygen saturation (StO2) of skin tissue (by tissue reflectance oximetry, TRO). Such systems may provide significant information relevant to physiology and clinical medicine. The aim of this research was to use such a system to study the synchronization of microvascular blood flow and oxygen saturation rhythms under normal and adaptive change conditions. Studies were conducted with 8 healthy volunteers – 3 females and 5 males of 21-49 years. Each volunteer was subjected to basic 3 minute tests. The volunteers were observed for between 1-4 months each, totalling 422 basic tests. Measurements were performed on the palmar surface of the right middle finger and the forearm medial surface. Wavelet analysis was used to study rhythmic oscillations in LDF- and TRO-data. Tissue oxygen consumption (from arterial and venal blood oxygen saturation and nutritive flux volume) was calculated for all volunteers during “adaptive changes” as (617±123 AU) and (102±38 AU) with and without arteriovenous anastomoses (AVAs) respectively. This demonstrates increased consumption compared to normal (495±170 AU) and (69±40 AU) with and without AVAs respectively. Data analysis demonstrated the emergence of resonance and synchronization of rhythms of microvascular blood flow and oxygen saturation as an adaptive change in myogenic oscillation (vasomotion) resulting from exercise and potentially from psychoemotional stress. Synchronization of myogenic rhythms during adaptive changes suggest increased oxygen consumption resulting from increased microvascular blood flow velocity.

The diffraction of a linearly polarized plane wave by a corner dielectric microstep of height equals of two incident wavelengths was studied using finite-difference time domain method and near-field scanning optical microscopy. It was shown that the corner step generates an elongated region of enhanced intensity, termed as a curved laser microjet. The curved laser microjet has a length of about DOF = 9.5 and the smallest diamet er FWHM = (1.94±0.15) at distance z = 5.5 . Keywords: dielectric corner step, near-field scanning optical microscopy, finite-difference time domain method, photonic nanojet 1. INTRODUCTION It has long been observed that the di ffraction of light by microobjects of near-wavelength size produces a near-surface focal spot [1]. In addition, with two competing processes—diffraction and focusing—proceeding simultaneously, the near-surface focal region becomes elongated, appearing as a photonic nanojet. The term “photonic nanojet” (PNJ) usually refers to a focal region found near a homogeneous micr osphere [2]. It has been nume rically demonstrated that the PNJ with the minimal diameter of FWHM = 130 nm = 0.325 ( is the wavelength) is generated as a result of diffraction by a polystyrene microsphere of diameter 1 µm ( = 400nm) [2]. The PNJ emerges wh en laser light is sharply focused using a microoptics element. The PNJ has a diameter smaller than the incident wavelength and shows an essentially enhanced intensity [2]. To distinguish between the laser beams discussed in this work and the PNJs, we introduced a new term, laser microjet (LMJ) [3]. The LMJs are defined as la ser beams generated by microoptics elements, that exhibit a near-wavelength diameter, a propagation length of several wavele ngths, and an intensity several-fold higher than that of the incident wave. It should also be noted that the LMJ in contrast with PNJ can be generated when light is diffracted not only by the microspheres but also by other microobjects. The experimentally measured minimal diameter of the LMJ was FWHM = 270 nm = 0.52 [4]. The polystyrene microsphere had a diameter of 3 µm ( = 400 nm), whereas the depth of focus, i.e. the LMJ length, was DOF = 3 . The LMJs have found uses in 3D nanolithography [5], plasmonics [6], and micromanipulation [7]. In Ref. [8] the LMJs were experimentally observed as a result of diffraction by a micropyramid: pyramid base 2 u 2 µm, height H = 400 nm, FWHM = 580 nm = 1.4 , DOF = 8 µm = 20 , where = 400 nm. The maximal intensity of the LMJ was found to be 4.12 times that of the incident light. In Ref. [7] the LMJ were generated by diffracting the beam by polymeric conical microaxisons. The microaxicon was of base diameter 200 µm, height H = 65 µm, n = 1.43, = 532 nm, FWHM = 0.6 µm, and DOF = 240 µm. In Ref. [9] the photonic nanojects were observed in a system of Si

The paper presents theoretical and experimental investigations of the structure of the spatial distributions of strain amplitudes for an oscillating surface using an optical interferometer. A conventional Michelson interferometer and an interferometer containing an acousto-optic cell have been studied. It has been shown that the maximum possible sensitivity of the device is 0.001 a, with the minimum strain amplitude reaching 0.001 a. Practical advantages of the interferometer with an acousto-optical cell have been realized.

A set of 450 noncentrosymmetric sulfides has been observed in reference to nonlinear optical properties. It has been found that on the plane of the oxide bond lengths the noncentrosymmetric sulfide crystals are dominantly positioned into a rosette of two intersected ellipses of ?acentricity?. The strongly non-monotonic dependency of nonlinear optical susceptibility (2) on the shortest chemical bond length L(E,M-S) has been obtained for sulfides. The suggested crystal chemistry analysis is useful for searching new noncentrosymmetric sulfide crystals. 2013 SPIE.

The modified Bridgman method with heat field rotation was used to grow -polytype single crystals of pure and 1, 2 and 10 mass % S-doped GaSe or solid solution crystals GaSe1-xSx, x = 0.002, 0.091, 0.412. The interaction of ultrashort laser pulses of 100 fs duration at 800 nm and 2 m with the grown crystals was studied at room temperature. Up to 3.4-fold advantage of S-doped crystals in limit pump intensity (no decrease in the transmission) was found under 800 nm pump at S-content increase up to 10 mass %. The advantage became a half less at 2 m pump due to a decrease of two-photon absorption in pure GaSe crystals. The spectral dependence of transient absorption is recorded with 37 fs resolution and interpreted. It was ascertained that first observable damage of high quality crystals is caused by dissociation of submicrometer thick surface layer to initial elements and do not influence the frequency conversion efficiency until alloying of dissociated Ga. Local microdefects, multiphoton absorption and transient transmission processes are identified as key factors responsible for damage threshold. 2013 SPIE.

The known crystal structures of borate compounds with general composition A I 2 MIII 2 B 2 O 7 (AI: Na, K, Cs, Rb) have been considered. The structures in space groups P63/m, P-3 1 c, P321 and P21/c have been found depending on cation combination. Criterion k = (r(M III )+r(B)+2r(O))/r(A I ) has been formulated and it controls the formation of trigonal K2Al2B2O7 (KABO) type structure. The existence of noncentrosymmetric KABO-type borates is possible over the range of k = 2.7 – 2.06. This range is promising for searching new borate crystals and solid solutions with pronounced nonlinear optical properties.

A high-quality KTiOAsO4 (KTA) single crystal has been successfully synthesized employing the high temperature solution growth technique with rotating and pooling. The XPS valence-band spectra have been measured for pristine and the 1.5 keV Ar + ion-bombarded thin (001)KTA plate cut from the crystal part that was without any optical inhomogeneities or domain boundaries. The present XPS measurements have revealed the existence of two O 2s subbands on the XPS spectrum of the pristine (001)KTA surface. It has been established that 1.5 keV Ar + ion bombardment of the (001)KTA surface causes the complete elimination of the O 2s sub-band related to oxygen atoms involved in the formation of Ti–O–As bonds in KTA. In addition, the XPS results reveal that such a treatment leads to a significant decrease of the relative intensity of the XPS As 5+ 3d core-level spectrum and causes the formation of the additional As 0 3d core-level spectrum in the topmost layer of the (001)KTA surface. The experimental data are compared to the results of the first-principles band-structure calculations of KTA.

The сentimeter-sized GaSe crystals doped with 0.01, 0.05, 0.1, 0.2, 0.5, 1, 2 at.% of Al and 0.025, 0.1, 0.5, 1,2 at. % of Er have been grown by the modified Bridgman method with heat field rotation. The crystals have been studied in comparison with GaSe crystals doped with 0.1, 0.5, 1, 2, 3, 5, 7, 10.2 wt.% of S, 0.01, 0.1, 0.5, 1, 2, 3, 5 wt.% of In and 0.01, 0.1, 0.5, 1, 2 wt. % of Te grown by the conventional Bridgman method. The distribution coefficient of Al in the grown GaSe:Al (≥0.1 at.%) crystals has been estimated to be ∼8⋅10-3 and it is within the range of 10-2-10-3 in Er-doped crystals. For the first time, the optimal doping levels have been estimated for Al and Er in GaSe as 0.01- 0.05 at.% for Al and ~ 0.5 wt.% for Er, respectively.

The structures of double molybdates with general compositions ALn(MoO 4 ) 2 (A – alkaline metals, Cu or Tl) have been considered and compared. It has been shown that the ionic radii ratio R Ln /R A is a key factor governing crystal symmetry. Different structure fields in ALn(MoO 4 ) 2 (A = Li + , Na + , K + , Cu + , Rb , Ag , Cs + , Tl + ) molybdates have been defined as a function of element composition. Keywords: double molybdate, formation, crystal structure. 1. INTRODUCTION The solid-state lasers based on Ln-doped oxide crystals have found a variety of applications in research and industry as sources of coherent illumination in visibl e and near-IR spectral ranges [1-3]. Among different oxide materials, complex molybdates containing rare earth ions are of special interest for the creation of effective hosting media for lasant ions because the isostructural substitution is possible over a wide concentration range [4-7]. Presently, there are a lot of known complex molybdate crystals that provide a wide field for selection of the crystals for different applications [8-16]. The physical properties of dominant majority of the molybdates, however, remain to be unknown or weakly studied. The binary molybdates with general composition ALn(MoO

The integration of multiple optical techniques within a single diagnostic device is used to address the difficulties in standardising measurement of cutaneous blood micro-dynamics caused by high variability. We demonstrate the benefits of simultaneous assessment of blood relative volume (Vb), microcirculation index (Im) and tissue oxygen saturation (StO2), during long-term examination of healthy volunteers. Consequently, five rhythmic components: endothelial, neurogenic, myogenic, breath and heart pulses were established showing high variability up to 30 - 50% as well as in initial parameters around 16%. All rhythmic components were synchronous with some latency between Im and StO2 in the myogenic component supports the hypothesis of strong correlation between peripheral hemodynamics and oxygen utilisation in tissues. Optical techniques are one of the promising non-invasive technologies for diagnosis of medical conditions. The integration of various techniques in an instrument and methodological framework that combines them in a single device using integrating algorithms for multi-modal diagnostics is particularly promising. Multi-functional laser non-invasive diagnostic systems (MLNDS), with up to 4 active channels are emerging, for example: laser Doppler flowmetry (LDF), tissue reflectance oximetry (TRO), laser fluorescence diagnostics (LFD), pulse oximetry and other. The most promising methods of optical non-invasive diagnostic methods are LDF and TRO. These methods are widely used in studying the dynamics of processes of blood microcirculation and oxygen transport and utilisation in biological tissues. The results of LDF measurements, index of blood microcirculation (Im) or perfusion, assessed in conventional perfusion units (PU), reveal a complex, non-periodic process. This variable component contains information on the modulation of blood flow. Use of spectral signal processing algorithms (LDF-graphs) for decoding and analysis provides information about the condition of vascular tone in terms of its contribution to the different mechanisms of micro-hemodynamic regulation (myogenic, endothelial, etc.) 1 . The TRO method determines relative blood volume (Vb) microcirculation in the surface layers of the soft tissues (skin, mucous membranes of the organs) and tissue oxygen saturation (StO2) of the microvasculature in the inspected area of biological tissue. There are isolated cases of spectral processing algorithms recorded signals (StO2- and Vb-graphs), being used to assess vasomotion and myogenic rhythms, for example 2 . We propose that analysis of oscillation signals recorded by TRO according to the frequency ranges, similar to LDF-graphs, is of practical interest in studying the parameters of microcirculation of blood, as the relationships between LDF and TRO attract the increasing attention of researchers in this field.

High average power, high repetition rate femtosecond lasers with μJ pulse energies are increasingly used for bio-medical and material processing applications. With the introduction of femtosecond laser systems such as the Spirit TM platform developed by High Q Lasers and Spectra-Physics, micro-processing of solid targets with femtosecond laser pulses have obtained new perspectives for industrial applications [1]. The unique advantage of material processing with subpicosecond lasers is efficient, fast and localized energy deposition, which leads to high ablation efficiency and accuracy in nearly all kinds of solid materials. The study on the impact of the laser processing parameters on the removal rate for transparent substrate using femtosecond laser pulses will be presented. In particular, examples of micro-processing of poly-L-lactic acid (PLLA) - bio-degradable polyester and Xensation TM glass (Schott) machined with Spirit TM ultrafast laser will be shown.

Resonant properties of the three-layer metallic cantilevers with 40 nm thickness are investigated. Two types of the nanocantilevers were fabricated: Cr-Al-Cr and Ti-Al-Ti. Resonant frequencies of the nanocantilevers were determined from the experimentally obtained resonant curves. Cantilever oscillations were excited by the electric force, the registration of the cantilever motion was performed by the optical lever method. Dependencies of the first and the second resonant frequencies on the cantilever length and width were experimentally obtained. The experimental data analysis and the comparison with the theoretical predictions were performed. Relations between the cantilever resonance properties and its dimensions and material are discussed.

The comparative performance analysis for single-dimensional and two-dimensional acousto-optic deflectors is presented. A new generalizing parameter equal to the product between the number of resolvable spots and acousto-optic diffraction efficiency is proposed. The possibility to use self-collimating modes in crystals for two-dimensional deflectors is discussed. A new geometry for a two-dimensional deflector with coinciding acoustic beams is proposed. This geometry is based on the deviation of energy transmission direction from the wave normal. The experimental test results for the TeO2 two-dimensional deflector with coinciding acoustic beams are presented. The test results are in good agreement with estimations.

Nephelometers and photoelectric counters are the most widely used instruments for measuring the characteristics of aerosol particles. Due to peculiarities of the design of the used nephelometer, as well as limited to visible range spectral interval, sensitivity of the method is restricted to submicrometer aerosol fraction. On the contrary, counters provide for the data on the particles with diameters of 1 μm and more. Thus, combination of these two instruments makes it possible to extend the range of obtaining the reliable data on the aerosol microstructure. In this paper, the results are discussed of simultaneous measurements of the size spectrum by means of nephelometer and photoelectric counter at artificial humidification of aerosol in the range of relative humidity from 20 to 90%.

Complex experiments were performed in the north-eastern part of the Black Sea and in the south-eastern part of the White Sea to study variability of the current fields and other characteristics of the sea, wind waves, and parameters of the near-surface atmospheric layer. Measurements were carried out from the onboard of the scientific research vessels by optical, radar and acoustic sensors. The heterogeneity of bottom topography in Black Sea had quasi-one-dimensional character. The case of the two-dimensionally heterogeneous relief of the bottom was investigated in the White Sea. The peculiarity of these experiments was simultaneous measurements from onboard of vessel synchronously with acquisitions of synthetic aperture radar (SAR) images of the Envisat and TerraSAR-X satellites. We have detected for the case of the quasi-one-dimensionally heterogeneous current a difference between the sea surface roughness above the shelf zone and the roughness at the deep bottom. We found that the inhomogeneities of the bottom topography can manifest as a change not only in the amplitude of different characteristics of surface wave and atmospheric near-water layer, but also in their frequency spectrum. In White Sea the special features of the flow of the powerful tidal current (up to 1 m/s) around the secluded underwater elevation and the spatial structure of surface anomalies in the field of these two-dimensional-heterogeneous currents are analyzed. The numerical simulation of the wind wave transformation in the field of two-dimensional- heterogeneous flows is carried out. The qualitative agreement of the calculation results with the experimental data is shown.

The devices entering an input information signal into an optical processing scheme are the most important elements in optical information and measurement systems. For a number of applications, acousto-optic cells are the most preferable such devices. The parameters of the devices entering the initial signal into optical processing schemes determine the maximum and operation characteristics of the entire system. The questions of the design, manufacturing, and characterization of acousto-optic cells for information and measurement systems are discussed.

The full-scale investigations of the action of internal waves and inhomogeneous currents on the wind waves and the near-water layer of the atmosphere were carried out in the White Sea in 2009 - 2011 yr. Measurements were carried out from onboard of the scientific research vessel "Ekolog" by optical, radar and acoustic equipment. Hydrometeorological conditions during observations varied essentially. Wind speed varied from 0 to 15 m/s, speed of current from 0 to 1 m/s. Data about the field of current during different phases of tide are received. Internal waves and their manifestations on the sea surface are registered. The special features of the flow of the powerful tidal current (to 1 m/s) around the secluded underwater elevation and the spatial structure of surface anomalies in the field of these two-dimensional- heterogeneous currents are analyzed. Data about a change in the characteristics of reflected from the sea surface radar signal in process of development of wind waves are received. Experiments on procedure finalizing of the determination of sub-surface current speed according to the numerical data of radar measuring complex on the base of ship radar Icom MR-1000 and FURUNO 1942 MK2are carried out.