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Strength charactristics of hybrid LasTig welds of thermomechanically processed steel
Šebestová, Hana ; Horník, Petr ; Mrňa, Libor
Thermomechanically processed steels achieve their high strength properties, while maintaining good ductility, thanks to their fine-grained structure assured by micro-alloying and strictly controlled process of rolling. Low heat input welding technologies are advisable. Nevertheless, high temperature gradients accompanying laser welding can lead to the brittle microstructures formation. The cooling rate can be controlled by preheating that we have realized with the heat of electric arc. Hybrid technology combining laser welding with tungsten inert gas (TIG) welding is referred to as LasTIG. The paper presents the effect of electric current that generates arc discharge on tensile strength, toughness, and fatigue life of LasTIG welds of S460MC and S700MC steels.
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Interferometric System for Length Calibration on a Metre Scale
Jedlička, Petr ; Mikel, Břetislav ; Řeřucha, Šimon ; Matěj, Z. ; Herman, O. ; Holá, Miroslava ; Jelínek, Michal ; Pavelka, Jan ; Číp, Ondřej ; Lazar, Josef
Interferometric system is designed to calibrate the measurement frame, used for periodic assessment of the inner geometry of the reactor active zone chassis. Calibration lenght is up to 3300mm.
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Comparison of frequency stability of laser wavelength standards over photonic networks
Pravdová, Lenka ; Hrabina, Jan ; Čížek, Martin ; Lazar, Josef ; Číp, Ondřej
In our work we present a metrological ampaign in which the stability of the 1540 nm normal laser located at the CESNET workplace in Prague was compared with the wavelength of the supercoherent laser transmitted from the ÚPT workplace in Brno via the 306 km phase-coherent transfer line Brno - Prague. The assembled acetylene standard was transferred to the CESNET workplace and a unit receiving coherent wave from the supercoherent laser stabilized by the optical frequency comb and the H-maser at the ISI workplace in Brno was put into operation. The optical frequency mixer with a photodetector recorded a frequency response between the acetylene optical frequency normal and the supercoherent laser distributed over the photonic network whose stability is given by the H-maser in the 15th order. We have verified that the laser normal meets the requirements of the BIMP Recommendation for the Practical Implementation of the Meter Standard.
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Utilization of hydrogen cyanide as an absorption media for laser spectroscopy
Hošek, Martin ; Řeřucha, Šimon ; Pravdová, Lenka ; Čížek, Martin ; Hrabina, Jan ; Číp, Ondřej
The main goal of our investigation is the use of hydrogen cyanide (concretely isotope H13C14N) as absorption medium for realisation of etalon of optical frequency. The advantage of HCN over typically used acetylene (isotopes 13C2H2 and 12C2H2) is the better availability and also the wider absorption spectrum in the 1550 nm wavelength band (telecommunication band). The hyperfine transitions in HCN were investigated in the 90‘, but because of technological limitations the measured data are not as precise as the data for C2H2. We aim on use of more developed methods (saturated absorption spectroscopy, optical frequency lock, beat-note against the optical frequency comb) for the measurement of more precise data of absorption lines of HCN. Our other goals will be to obtain the data enough precise to allow the use of them in Mise en pratique.
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Measurement of laser welding process by high-speed camera and photodiode
Horník, Petr ; Mrňa, L. ; Šebestová, Hana
Laser welding monitoring system can be realized optically. The solution with photodiode sensing welded area has advantage of simplicity and low cost but faces many challenges. Multi-photodiode measurement show dependency of the measured intensity on the photodiode position. Subsequently, the measured values were compared with high-speed camera images. Using the correlation coefficient, the area providing the same information as photodiode measurement was determined in the images.
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Laser ablation of calcium atoms for laser cooling experiment
Grim, Jakub ; Pham, Minh Tuan ; Číp, Ondřej
Our work describes two most common methods of generating neutral atoms needed for experiments with trapped and cooled ions. The easiest but not most effective way of the neutral atoms generating is to use a heated oven. A better method allowing a fine control of generating atoms is to use a pulsed laser ablation. A vacuum chamber with Ca atoms source and necessary optics was assembled. Detection of generated particles was achieved by laser-induced fluorescence and sensitive camera. The paper consists of measurement of both method of generating the atoms.
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Stable optical frequency transfer between ISI and CESNET workplaces
Čížek, Martin ; Pravdová, Lenka ; Hucl, Václav ; Jelínek, Michal ; Hrabina, Jan ; Řeřucha, Šimon ; Mikel, Břetislav ; Lazar, Josef ; Číp, Ondřej ; Smotlacha, V. ; Havliš, O. ; Vojtěch, J.
The contribution reports on the current state of a 306km long experimental line for transfering stable optical frequency from a telecommunication band laser standard between ISI CAS (Brno) and CESNET (Prague). The bidirectional link uses a telecommunication fiber with a dedicated DWDM window of 1540-1546 nm.1540-1546 nm. In the Czech rep. this technology can be utilized currently in two fields: remote comparisons of optical frequency standards and remote callibration of instruments (optical spectral analyzers) in industrial applications that do not allow transporting the device to a specialized laboratory. The stability of the optical frequency transfer was evaluated. A long-term measurement of transport delay was conducted. \n
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Proceedings of multidisciplinary conference LASER58
Růžička, Bohdan
Conference LASER58 is a multidisciplinary and intersectoral event where different kind of specialist can meet each other. They come from various environments (private company, university, public research organization etc.). Their common denominators are laser, optics and its applications.\n\n
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