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Low-coherence interferometry in industrial metrology
Buchta, Zdeněk
The paper describes an experimental arrangement for optical pumping of rubidium based on a high-power laser diode and high power lased diode array. The emission spectrum of the laser diode array was narrowed by external injection locking technique by means of cw Ti:Sa resp. an extended cavity laser (ECL) based on a high-power laser diode. The laser system was designed to be a crucial part of the HpXe (hyperpolarized xenon) production process.
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Charakterizace supersonického radikálového zdroje
Mašát, M. ; Votava, Ondřej
Experimental setup for spectroscopic measurements of molecular radicals at low temperatures is presented. Radicals are created in a DC discharge and cooled by supersonic expansion. Absorption spectroscopy in the near IR region is used to probe the neutral transient species formed in the discharge, using tuneable extended cavity diode lasers. Initial characteristics of the radical source are presented; discharge current-voltage characterization, molecular OH radical concentrations and temperature were measured.
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Absolutní frekvenční posuvy jodem stabilizovaných laserových etalonů zpusobené čistotou jodu absorpčních kyvet
Hrabina, Jan ; Jedlička, Petr ; Číp, Ondřej ; Lazar, Josef
Results of measurement of purity of a set of iodine cells for laser stabilization made at our institute are presented. The purity was tested by improved method based on measurement of induced fluorescence and evaluation by the Stern-Volmer formula. This method was improved by innovation of the fluorescence detection system by introducing compensation for the pumping laser spectral and power instabilities. Further the absolute frequencies of selected iodine hyperfine transitions were measured in direct laser frequency comparison performed with a set of iodine-stabilized Nd:YAG laser etalons with the reproducibility well below the kHz level. The results indicating the iodine cell purity are presented with relation to the absolute frequency shifts. This highlights the influence of iodine cell quality onto the stability and absolute frequency of lasers etalons and also shows the way towards improvements of the iodine cell manufacturing technology.
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Využití modelových spekter ke stanovení vhodných parametrů kapilárního výboje pro zesílenou emisi Balmerova alfa – přechodu H–like N (13,4 nm)
Štraus, Jaroslav ; Koláček, Karel ; Schmidt, Jiří ; Frolov, Oleksandr ; Prukner, Václav
Our capillary-discharge driver CAPEX-U, as many other pulsed-power devices, requires very accurate triggering of high-voltage gas switch. Laser-triggered switches offer many advantages over electrical triggered ones in terms of reproducibility, reliability, suitability for multi-gap or multi-channel operation and electrical isolation from the main high-voltage pulse. Results on the simultaneous initiation of four-channel high voltage spark gap by a neodymium dopped yttrium aluminium garnet (Nd:YAG, λ=1064 nm) laser are presented. The switch is pressurised with SF6 and N2 and holds off voltage about 500 kV at a gap separation of 13 mm. Electrical parameters of the spark channels are obtained from the comparison of experimental and modelling (equivalent circuit) results.
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Měření čistoty jódu v absorpčních kyvetách pro frekvenční stabilizaci laserů
Hrabina, Jan ; Petrů, František ; Jedlička, Petr ; Číp, Ondřej ; Lazar, Josef
In the contribution we present a system for measurement of iodine purity by means excitation of a selected strong transition, measurement of induced fluorescence and evaluation by the Stern-Volmer formula. The arrangement is based on a pumping Ar-ion laser tuned to the transition of interest but its linewidth far exceeds the transition. Frequency noise of the laser is effectivelly reduced by monitoring the fluorescence in a second, reference iodine cell and together with monitoring of the laser power enables cancelation of the frequency noise influence which generates errors by demodulating on the absorption profile. The level of the scattered light is subtracted as well. All the measured data are digitally processed and the experiment is fully computer controlled.
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