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1
Content available remote

Investigations of Quantum Cascade Lasers for Free Space Optics Operating at the Wavelength Range of 8-12 μm

100%
Nowakowski M., Gutowska M., Szabra D., Mikołajczyk J., Wojtas J., Bielecki Z.
Acta Physica Polonica A
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2011
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vol. 120
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issue 4
705-708
EN
The paper presents analysis and preliminary investigations of quantum cascade lasers for free space optics. The lasers radiate in the long wavelength IR spectral range (8-12 μm). Because of lower effects of radiation scattering than in the case of 1.5 μm free space optics, better transmission range can be obtained. The main task of the work was experimental investigation of quantum cascade lasers taking into consideration free space optics applications. In the research, quantum cascade lasers operating in both pulse and continuous wave modes were used. The lasers spectra as well as the operation characteristics (e.g. voltage vs. current) were measured. In conclusion, the quantum cascade lasers parameters for free space optics system applications are summarized.
2
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Multispectral Laser Head for Terrain Identification and Analysis

80%
Mierczyk Z., Zygmunt M., Kaszczuk M., Muzal M.
Acta Physica Polonica A
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2013
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vol. 124
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issue 3
502-504
EN
The reflectance profilometer, constructed in Institute of Optoelectronics, Military University of Technology, is an optoelectronic device based on the laser remote sensing technique, designed for use on unmanned aerial vehicles. The main task of the profilometer is to analyze the reflectance signals for laser radiation from the multispectral range: 850, 905, and 1550 nm. On the basis of the analysis the profilometer enables two fundamental functions: to define the shape of the ground and identify elements of terrain coverage, along with analysis of its physicochemical properties. The reflectance profilometer is a system based on a modern concept of measurement, allowing to obtain unique information about tested objects, whose measurements or detection are not possible by means of thermal imaging systems and systems operating in the visible range. The received information is visualized in 3D format, which allows for more accurate, precise and comprehensive way of analyzed area model presentation.
3
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Models of Interactions of Laser Beams with Materials of Interest for Optical Components and Provoked Damages

80%
Srećković M., Ilić J., Kovačević A., Pantelić S., Latinović Z., Borna N., Ćosović V.
Acta Physica Polonica A
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2007
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vol. 112
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issue 5
935-940
EN
Models of interactions of laser beams with materials of interest for optical components are presented in this paper. Special attention is paid to damages which appear within both active materials and optical components along the path of a propagating beam with theoretical treatment via various models.
4
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Ruby Laser Interaction with Austenite Structural Materials

80%
Milosavljević A., Petronić S., Srećković M., Ristić S., Nešić I., Pljakić R., Negovanović V.
Acta Physica Polonica A
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2009
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vol. 115
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issue 4
823-825
EN
The investigations were carried out on chrome nickel steel and nickel based superalloy samples thermo-mechanically treated to obtain optimal mechanical properties and surface stability. Chrome nickel steel and a few nickel based superalloys samples were exposed to the laser beam before creep deformation process. The second group of nickel based superalloy samples were exposed after the creep deformation. The damages occurred by exposing of chrome nickel steel and nickel base superalloy samples to the ruby laser were analyzed by scanning electron microscope and energy-dispersive X-ray spectrometry. In this paper, the influence of laser dynamical regime (MW/mm^{2}) to the microstructural changes of heat treated chrome nickel steel and nickel based superalloy are analyzed and discussed.
5
Content available remote

Optodynamic Characterization of Laser-Induced Bubbles

80%
Gregorčič P., Možina J.
Acta Physica Polonica A
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2007
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vol. 112
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issue 5
1137-1143
EN
Laser-induced bubbles can be caused by an optical breakdown in water. They are a result of the optodynamical process where the energy of a high intensity laser pulse is converted into the mechanical energy through an optodynamic conversion. At this process the absorbed optical energy causes plasma expansion that in turn initiates dynamic phenomena: spreading of a shock wave and the development of a cavitation bubble. When the cavitation bubble reaches its maximum radius it starts to collapse due to the pressure of the surrounding liquid. This collapse in turn initiates a new bubble growth and bubble collapse. The process therefore repeats itself, resulting in so-called cavitation-bubble oscillations, with a new shock wave being emitted after every collapse. We present an optodynamic characterization of cavitation bubble's oscillations based on a laser beam-deflection probe. Employed setup enabled us one- or two-dimensional scanning with deflections of a laser probe beam. Deflections were detected with a fast quadrant photodiode.
6
Content available remote

Study on the Breakdown Mechanism of Fabrication of Micro Channels in Fused Silica Substrates with ps Laser Pulses

80%
Li S., Bai Z., Qin S.
Acta Physica Polonica A
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2013
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vol. 123
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issue 1
67-72
EN
A new microchannel fabrication technology for fused silica substrate is presented. A mode-locked laser was used to fabricate straight microchannels in a fused silica substrate by laser plasma-induced plasma. The depth of the channels is up to 5 mm and there are no thermal cracks around the channel. We studied the ionization mechanism of optical breakdown formed by laser pulses and discussed the optical breakdown threshold. A mechanism is proposed to explain the formation of the microchannels and the characteristics of the microchannels are analyzed through the laser pulse characteristics.
7
Content available remote

Surface Modification of Metallic Targets with Ultrashort Laser Pulses

80%
Gakovic B., Stasic J., Petrovic S., Radak B., Krmpot A., Jelenkovic B., Trtica M.
Acta Physica Polonica A
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2009
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vol. 116
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issue 4
611-613
EN
Interaction of pulsed femtosecond Ti:sapphire laser (160 fs), operating at high repetition rate (75 MHz) at 800 nm, with nickel-based superalloy Inconel 600 and tungsten-titanium (WTi) target was studied. The WTi target was in form of thin film deposited on silicon substrate. Low laser fluence of maximum 50 mJ/cm^{2} had modified the target surface during irradiation/exposure time of seconds or minutes. The radiation absorbed from the laser beam generates at the surface a series of effects, such as direct material vaporization, formation of clusters, etc. Morphological features of the targets can be summarized as: (a) intensive removal of material and crater appearance; (b) creation of nanostructures; (c) microcracking, etc. Ablation of Inconel 600 surface is effective, resulting in formation of holes with small diameter ( ≤ 10 μm) and relatively large depth ( ≤ 50 μm). In case of WTi target/thin film, the surrounding rim is not so expressed, and crater depths are lower. It can be concluded that the average laser power of the order of watts, pulse energies of the order of nanojoules and high repetition rates (MHz range) can successfully modify metallic materials.
8
Content available remote

Fine-Scale Structure Investigation of Nimonic 263 Superalloy Surface Damaged by Femtosecond Laser Beam

80%
Milosavljevic A., Petronic S., Sreckovic M., Kovacevic A., Krmpot A., Kovacevic K.
Acta Physica Polonica A
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2009
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vol. 116
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issue 4
553-556
EN
Due to the specific conditions of manufacturing, processing and utilization of nickel-base superalloys, the implementation of contemporary precision techniques is necessary in the research of the alloys features. Multi-component nickel-base superalloys, with about of 50% of nickel content, are commonly exploited in the conditions of high temperatures and pressures as well as in various aggressive operating environments. For successful quality control, which includes the monitoring of the changes in the alloy microstructure, fine-scale structure investigations are necessary. In this work, the samples of nickel-base superalloys have been exposed to 800 nm femtosecond laser in various operating regimes. Surface damages and dents caused by femtosecond laser pulses have been observed by optical and scanning microscopy.
9
Content available remote

Microstructure Changes of Nickel-Base Superalloys Induced by Interaction with Femtosecond Laser Beam

80%
Petronic S., Drecun-Nesic S., Milosavljevic A., Sedmak A., Popovic M., Kovacevic A.
Acta Physica Polonica A
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2009
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vol. 116
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issue 4
550-552
EN
The investigation was performed on nickel-base superalloys, with nickel being the most influential alloying ingredient. After thermo-mechanical preparation and corresponding processing, femtosecond laser beam machining has been performed. The laser wavelength was 800 nm. The exposition time, during which the samples have been exposed to the pulses of femtosecond laser beam varied, as well as the average output power. The changes of both the output power and the exposition time enabled the samples to be irradiated with different total energy during each exposition. The changes in samples microstructure were observed with optical and scanning electron microscopy, with energy-dispersive spectrometry, and analyzed as well. Microhardness measurements of both base material and ablated spots have been performed.
10
Content available remote

Laser Interaction with Material - Theory, Experiments and Discrepancies

70%
Srećković M., Ilić J., Davidović M., Djokić B., Tomić Ž., Latinović Z., Družijanić D.
Acta Physica Polonica A
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2009
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vol. 116
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issue 4
618-621
EN
The experimental treatment of chosen material with laser beams, starting from continuous wave up to fs pulses, produces the necessity to find the common and sophisticated theoretical approaches to interaction modeling. For chosen materials, some laser treatment and damage analyses are performed. The provoked stresses and parameters of transport processes (penetration depth) are calculated by using the programs for electrical circuit analyses. Some inconsistencies in the treatment of large area laser-material interaction are discussed.
11
Content available remote

Single Pulse Laser Ablation of AISI 316L Stainless Steel Surface Using Nd:YAG Laser Irradiation

61%
Demir P., Kacar E., Akman E., Demir A.
Acta Physica Polonica A
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2014
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vol. 125
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issue 2
439-441
EN
The interaction of single-pulse Nd:YAG laser, operating at 1064 nm wavelength and 6 ns pulse duration, with AISI 316L stainless steel target surface was investigated experimentally and theoretically. Surface modification of stainless steel using laser irradiation was studied by observing the effects of varying incident laser pulse intensities on surface morphology. Surface structure of laser treated stainless steel was determined by optical microscopy and profilometry analyses. Numerical calculation by heat transfer equation was performed for single laser pulse irradiation. The results, obtained by theoretical and experimental processes, of the interaction between single-pulse Nd:YAG laser irradiation and AISI 316L stainless steel target surface are reported.
12
Content available remote

Microstructure Development in Multilayer TiB_x/TiSi_yC_z Coatings during Post-Deposition Heat Treatment

51%
Twardowska A., Rajchel B., Morgiel J., Mędala-Wójcik M.
Acta Physica Polonica A
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2016
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vol. 130
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issue 4
1124-1126
EN
Multilayer amorphous TiB_{x}/TiSi_{y}C_{z} coatings were formed by duplex treatment: dual beam ion beam assisted deposition and pulsed laser deposition. Post-deposition heating was applied to activate crystallization in the coating. In situ transmission electron microscopy heating experiments were conducted in the temperature range 20-600°C. Crystallization of TiB₂ phase in TiB_{x} layers begun at 450°C, while TiSi_{y}C_{z} layers retained nearly amorphous up to 600°C.
13
Content available remote

Applications of a Compact "Water Window" Source for Investigations of Nanostructures Using SXR Microscope

51%
Torrisi A., Wachulak P., Fahad Nawaz M., Bartnik A., Adjei D., Vondrová Š., Turňová J., Jančarek A., Fiedorowicz H.
Acta Physica Polonica A
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2016
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vol. 129
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issue 2
169-171
EN
A compact soft X-ray microscope based on a nitrogen double-stream gas puff target soft X-ray source, operating at He-like nitrogen spectral line at the wavelength of λ =2.88 nm is presented. The desk-top size microscope was successfully demonstrated in transmission mode using the Fresnel zone-plate objective and it is suitable for soft X-ray source microscopy in the "water window" spectral range (λ = 2.3÷ 4.4 nm). Details about the soft X-ray source source, the microscope and an example of application in the biomedical field are shown and discussed.
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