Showing papers presented at "International Conference Laser Optics in 2014"

100 kW CW fiber laser for industrial applications

Abstract: The world’s most powerful laser system for industrial applications would be presented. Ytterbium fiber laser combines record 101.3 kW output power, continuous-wave operational mode and an excellent beam quality. Beam parameter product (BPP) does not exceed 16 mm x mrad, when we use 300 μm x 10 m feeding fiber, or near 25 mm x mrad, when fiber-to-fiber output coupler with 500 μm x 50 m process fiber is used. Emission wavelength is 1070 nm. High wall-plug efficiency 35.4%, compact laser cabinet and total weight less than 3600 kg open the new opportunities in different industrial and mobile applications. Keywords—Lasers, fiber; Infrared and far-infrared lasers

Upgraded raman lidar with ultraspectral resolution

Abstract: Upgraded Raman Lidar with spectral resolution of dλ/λ≤10 have been design and elaborated for the aerosearch of leaks on the main gas pipelines. The sensing is carried out by 7ns pulses of DPSS laser with energy of 10 mJ at 300Hz frequency and wavelength of 261.7 nm. Polycromator have been implemented on base of the concave grating (N=1200 mm) and operates in 4th diffraction order. Lidar measures the leaks of CH4 with concentration of 2 ppm and above. Scanning in angles of ±30о and at frequency of 20 Hz allows to carry out measurements on inclined courses.

Design of mobile hybrid laser-arc welding system on the base of 20 kW fiber laser

Abstract: Hybrid laser arc welding is one of the most prospective technologies for joining of gas and oil pipes, bridge sections and building constructions. The main advantage of hybrid welding is a possibility to weld by one path materials with thickness up to 15 mm and more, including new high strength steels. Hybrid processes allow increase productivity and tolerance, provide weldability in comparison with laser ones and increase productivity and quality of weld, decrease distortion in comparison with arc welding. In spite of all advantages, the usage of this technology in the case of real production is restricted by high complicity of the process [1] and appearance of porosity, cracks, spiking and hamping in the weld seam, especially in welding of alloyed steels. Important problem for widening of usage of hybrid technology is absence of mobile welding systems, which can be used for welding of non-turnable pipes joints, off-shore constructions, bridge sections and so on.

Laser sensor for airborne prospecting method of oil & gas deposits

Abstract: Remote laser spectroscopy availability for airborne search of the oil-and-gas deposits has been examined. Experiments were carried out under the CARS circuit. Minimal concentrations of heavy HG of 200 ppb are remotely measured in laboratory. As estimations have shown the reliability of heavy HG detection can exceed 80 % at the integration method of seismic prospecting and remote laser sensing in CARS circuit.

Monitoring of methane emissions in the Arctic by laser sensing to assess climate change

Abstract: Currently Arctic dramatic changes due to global warming, in addition, it is influenced by globalization and cross-border pollution . Feedback mechanism between the surface and the Arctic climate system will enhance the warming effect, while the ground ice in the Arctic is increasingly contributing to global sea level rise. Need to keep track of all the changes taking place in the Arctic, document them, to simulate changes in the cryosphere and their consequences. Permafrost temperature and thickness of the active layer , in spite of some differences in certain regions, have generally increased throughout the Arctic . [1]

Features processing lidar signals in the GHz frequency range

Abstract: Features processing and registration of lidar signals in the GHz frequency range have been studies. Model of the interaction between the components of the system with the required level of performance and accuracy was developed.

Application of modern method of calculating uncertainty to microwaves and opto-electronics

Abstract: Recent approach is used to calculate uncertainty for an microwave and optoelectronic system. The deduced global uncertainty on spectral density of phase noise in the range of 2 dB is improved. Keywords—uncertainty; opto-electronics; microwaves

Optimization of structuring silicon-based thin film solar modules using means of laser scribing

Abstract: At the moment search, production and use of renewable energy sources is a very actual task. One of approaches, which allow to resolve this problem is development of high-effective thin-film solar cells based on silicon. Recently laser technologies have been widely used to increase energy conversion efficiency. However some disadvantages of use of laser processing are that the areas of the solar cell, treated by laser, become unable to participate in the transformation of energy. Therefore, it is, necessary to minimize the area of the solar cell treated by laser.

1,64 mkm Er:YAG laser resonantly pumped by a solid state Er:glass laser

Abstract: We report on theoretical and experimental studies of Er :YAG pulsed laser working in a quasi-three-level scheme. A numerical simulation of an optical multiple laser scheme is carried out. Electro-optically Q-switched operation of an Er:YAG laser at 1645 nm end-pumped by a laser Er-Yb phosphate glass is demonstrated. Pulse energies up to 3 mJ have been generated at a pulse repetition frequency of 10 Hz.

Robust eye-safe compact laser

Abstract: A compact eye-safe laser for atmosphere lidar was developed. The device is Nd:YLF laser with KTP OPO, wavelength is 1,54 um, repetition rate is 50 Hz and Q-switched pulse energy is 8 mJ. The laser rod and laser diodes are conductive cooled. The device has run tests with 5×10 shots without parameter decrease. Keywords— Eye-safe laser; OPO; optical parametric oscillator; Nd:YLF laser.

Ring Laser Gyroscope for accurate angle metrology

Abstract: An apparatus for high precision angle metrology, based on a mid-scale ring laser gyroscope, is in development at the Italian Metrologic Research Institute (INRIM). The aim is to build a portable instrument with an accuracy in the range of some tens nanoradiants. Keywords—Ring laser Gyroscopes; angle metrology

Ultra compact eye-safe laser for rangefinding

Abstract: We demonstrate an eye-safe diode pumped ultra compact Yb:Er:glass laser with 3 mJ pulse energy in free running mode with repetition rate 1 Hz. We investigate phototropic gates for Yb:Er:glass lasers. The developing laser operates in a wide temperature range. Keywords—eye-safe laser; rangefinding; passive Q-switches; Yb:Er:glass; glass-ceramics; compact laser.

Femtosecond point-by-point inscription of fiber Bragg gratings through the polyimide coating

Abstract: The paper presents the results on Bragg gratings inscription in non-photosensitive optical fibers through the polyimide protective coating by femtosecond radiation with the wavelength of 1026 nm. The Bragg gratings inscribed by a point-by-point method in specialized optical fibers: high-temperature resistant Fibercore SM1500(9/125)P and hydrogen resistant Fibercore SM1500SC(9/125)P have reflectivity 50-90%.

Propagation and focusing of modes of the dielectric resonator of terahertz laser

Abstract: Theoretically on the basis of the vectorial Rayleigh-Sommerfeld theory and experimentally using terahertz radiation of the waveguide laser (λ = 0.4326 mm) the physical features of propagation and “moderate” or “sharp” focusing of laser beams of radiation are investigated in free space which described by modes of circular hollow dielectric waveguide with different spatial polarization.

Spatially resolved speckle correlometry in application to media structure characterization

Abstract: We propose an original speckle-correlometry method for the structural analysis through a random multiple scattering media with complex dynamics and structure. The use of a localized radiation source and spatial ring filtration of scattered field give the opportunity to select the partial components of scattered field. In this work, the dynamic process of gel formation beginning from the stage of sol to the stage of gelling are investigated and the experimental data are presented. The object under study consist of 0.28 %weight fraction of gelatin dissolved in water and 1 gram per liter (gL) and 100 mg per liter (gL) of TiO2 for optical scattering. Keywords— dispersive media; scattering; laser light; speckle correlometry

Laser plasma sources of soft X-rays and extreme ultraviolet (EUV) for application in science and technology

Abstract: Summary form only given: Application of laser plasma sources of soft X-rays and extreme ultraviolet (EUV) developed in our laboratory in various areas of plasma physics, nanotechnology and biomedical engineering are presented. The sources are based on interaction of high-intensity nanosecond laser pulses from commercial Nd:YAG lasers with gas puff targets formed by pulsed injection of gas under high-pressure. The use of a gas puff target instead of a solid target makes possible to generate plasmas emitting soft X-ray and EUV radiation without target debris production.

Oceanological Monitoring of Fishing Areas using Lidars

Abstract: Some advantages of lidar remote sensing methods are described along with the tasks for solving which these methods are used. Examples of modern lidar systems designed for the oceanological monitoring are also given. The lidars are successfully used to solve a wide range of fishery problems: measuring the hydrooptycal characteristics of the sea surface layer, locating fish schools and estimating the corresponding biomass (1,2), finding the phytoplankton concentration (3), registering the water pollution (4), etc. The remote character of the lidar measurements allows carrying them out from aboard a moving carrier (plane, ship). No restrictions are imposed on the speed and course of the carrier. Lidar sounding allows measurements in the water without submerging any devices and therefore without affecting the processes and objects studied. Ship lidar "Gidrobiont" (SLG) was designed by JSC "Giprorybflot" in cooperation with the Institute of Oceanology RAS for installation on research and fishing ships. The main feature of the SLG is the combination of polarization and spectral channels in its design. Two methods are used for processing the echo signal formed during sounding of sea water with short unidirectional laser pulse. The first one analyses the time dependency of degree of polarization of the echo signal and therefore provides the possibility of getting vertical profiles of hydrooptical characteristics and locating and depth measurements for different inhomogeneities in sea water. The second one uses spectral analysis of the echo signal allowing locating phytoplankton clusters in the surface water layer and determining their characteristics.

High-efficiency oscillations at 1940 nm and 2070 nm in diode-pumped Tm:Lu 2 O 3 ceramics lasers and their OPO frequency converision

Abstract: CW and repetitively-pulsed oscillations at 1940 nm or 2070 nm in diode-pumped Tm:Lu2O3 ceramics lasers were studied and optimized. Mid-IR optical parametric oscillators based on AgGaSe or ZnGeP nonlinear crystals pumped by the Tm:Lu2O3 laser radiation were examined.

Selective Laser Melting and Direct Metal Deposition: From process fundamentals towards advanced products

Abstract: Selective Laser Melting (SLM) is a powder-based and laser assisted additive manufacturing technology capable to produce parts layer-by-layer from a 3D CAD model. Nowadays SLM is used in various industrial domains including aerospace, automotive, electronic, chemical and biomedical, as well as other high-tech areas. Industrial interest is focussed on manufacturing of fully functional objects with high geometrical complexity and excellent mechanical properties. Properties of the manufactured parts depend strongly on each single laser-melted track and each single layer, as well as the strength of the connections between them.

Phase correction of laser beam passed through turbid medium

Abstract: Model of laser beam propagation in turbid medium with variable parameters was suggested. Phase and intensity distribution of scattered light with different wavelengths and various whether conditions (particles sizes, concentrations, refractive indices and medium depths) were obtained.

Cleaning and surface treatment with pulsed high power fiber lasers

Abstract: Surface treatment with high power pulsed fiber lasers gets more and more interesting to wide range of applications due to higher available average power and pulse energy. The average power is either increased by higher repetition rates or higher pulse energy. New laser concepts allow the parallel combining of several fiber laser modules up to an average power of several kilowatts. These lasers increase the efficiency of the processes by high removal rates. This paper gives an overview on the various applications of surface treatment such as cleaning of molds, depainting and surface preparation for welding and gluing. Keywords—Laser cleaning, pulsed fiber lasers, de-coating, surface modification

Testing of Cr:ZnSe laser with intracavity methane cell in 77–300 K temperature range

Abstract: The mid-IR cw tunable solid state two-mode Cr 2+ :ZnSe laser with intracavity methane cryocell was developed. The laser was applied for sub-Doppler spectroscopy of (ν1+ν4) vibrational-rotational band of methane and observation of narrow resonances of saturated dispersion at λ = 2.36 μm. The new technique of low pressure methane gas cooling was used instead of liquid nitrogen "jacket" design applied in our previous work. Parameters of saturated dispersion resonances were estimated in 77-300 K temperature range. The experiments confirmed that laser with the new "dry cooled" methane cell has prospectives for reaching a short- term frequency stability at the level of 10 -15 - 10 -16 and can be used as a compact device.

3 mJ@3.3 kHz single mode single-frequency end pumped pulsed Nd:YAG ring laser

Abstract: End pumped Nd:YAG ring laser with electro-optical Q-switcher was built. Pumping of each laser rod is provided by 45 Watt laser diode module coupled in high-brightness fiber. Single-frequency and unidirectional performance of laser is provided with injection seeding. End overheating of active rod was reduced by using low-concentration active medium. Thermo-optic distortions were compensated.

The seed signal for the parametric amplification channel of multiterawatt femtosecond laser system

Abstract: The progress in the development of a multiterawatt femtosecond diode-pumped system with high pulse repetition rate based on Yb3+-doped media is reported. An ultrabroadband supercontinuum using highly-nonlinear photonic crystal fibre is generated.

Terahertz spectral characteristics and optical properties of normal and pathological skin, cornea and their components

Abstract: The prospect of development of the contactless diagnostics method of pathological skin and cornea in the terahertz frequency range was shown. The stimulation of the nerve cells growth by low-intensity terahertz radiation was observed. Probably the selection of terahertz radiation parameters allows expecting the acceleration of skin and cornea regeneration in-vivo. Keywords— Terahertz spectroscopy, skin, cornea, fibroblasts, nerve cells

Ophthalmic system based on excimer KrCl laser (223 nm)

Abstract: Review of development and clinical trials conclusions of the ophthalmic KrCl (223 nm) laser system is presented. Medical safety, physical and technical advantages of the new laser system in comparison with widespread ArF (193 nm) laser systems for refractive surgery are demonstrated. The method of eye virus diseases treatment by usage of the KrCl laser radiation is proposed.

Comparison study of non-centrosymmetric materials from aminopyridines

Abstract: Performed study on the co-crystallization of heterocyclic molecules of aminopyridine series with a nonlinear optical chromophore (4-Nitrophenol) and receiving molecular crystals with non-centrosymmetric crystal lattice based on them. Experiments on the growth of single crystals of these substances by slow evaporation technique in a closed volume. The dependence of the crystal symmetry on the growing conditions. A comparative study of nonlinear optical properties of crystals based on aminopyridines and measured their nonlinear optical coefficients.

Profiling of the forest fire aerosol plume with multiwavelength Raman lidar

Abstract: Vertical profiles of biomass burning aerosol parameters, such as effective radius, volume density and the complex refractive index, during forest fire in North America in August 2013 are studied. Aerosol extinction and backscattering coefficients measured at multiple wavelengths by Raman lidar based on tripled Nd:YAG laser are inverted to the particle microphysical properties.