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Radio frequency resonator for feeding ion trap
Jedlička, Petr ; Pham, Minh Tuan ; Čížek, Martin ; Pavelka, Jan ; Lešundák, Adam ; Hucl, Václav ; Hrabina, Jan ; Řeřucha, Šimon ; Lazar, Josef ; Číp, Ondřej
Two versions of resonators were designed and manufactured - asymmetric and symmetric.\nThe resonator consists of a coil and capacity of ion trap which makes parallel resonant circuit.\nEnergy is supplied to the resonator through the coupling inductance. Resonator assembly was equipped with outputs for monitoring high-frequency voltage. Both versions have been tuned and tested.\n\n
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A pair of phase-synchronized semiconductor lasers for length metrology
Hucl, Václav ; Holá, Miroslava ; Čížek, Martin ; Řeřucha, Šimon ; Pham, Minh Tuan ; Pravdová, Lenka ; Lazar, Josef ; Číp, Ondřej
Semiconductor lasers are increasingly widespread in areas that have been so far dominated by He-Ne lasers. One of such areas is the length metrology, where He-Ne laser operating at 633nm wavelength is still a traditional source of coherent light for laser interferometers distance measuring. The advantages of semiconductor lasers compared with He-Ne laser are greater optical power and a significantly wider range of wavelength tuning without mode jumps. Another advantage is the possibility of frequency modulation of wavelength of the laser diode by directly changing the injection current. The benefits predetermine these laser diodes for the realization of dual-frequency laser sources for heterodyne interferometry. In this case, using a phase-locked loop technique the optical frequency of a laser diode is locked to the optical frequency of another laser diode with a certain frequency offset in the MHz order. In our contribution we present utilization of DBR laser diodes in implementing a dual-frequency laser source for laser interferometry with heterodyne detection.\n
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Phase coherent transfer of stable optical frequency for sensory networks
Čížek, Martin ; Pravdová, Lenka ; Hucl, Václav ; Řeřucha, Šimon ; Hrabina, Jan ; Mikel, Břetislav ; Lazar, Josef ; Číp, Ondřej
Using long-haul optical fiber links for phase coherent transfers of stable optical frequencies has been developed by metrological laboratories for at least a decade. Present boom of optical fiber sensors puts a demand on transferring this technology from laboratories to industrial practice. A remote calibration of fiber Bragg grating tensometers can be an example. In our contribution we present a 306 km long fiber link between laboratories of ISI in Brno and CESNET in Prague. The line uses a telecom fiber with a dedicated DWDM window at 1540-1546 nm. The setup implements a phase coherent transfer of a laser standard working with 1540.5nm wavelength and a bi-directional transfer of 1PPS timestamps from radiofrequency standards at the both ends of the line. A long-term measurement of transport delay fluctuations and relative stability of the line are discussed.
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Laser cooling of the trapped ions for frequency and time metrology
Číp, Ondřej ; Pham, Minh Tuan ; Čížek, Martin ; Lešundák, Adam ; Hucl, Václav ; Hrabina, Jan ; Řeřucha, Šimon ; Jedlička, Petr ; Lazar, Josef
In the laser cooled trapped ions field current research is oriented to yield isolated ions in their basic state of the motion. The detection of the Doppler cooled iont excitation to its quadrupole transition of the electronic structure gives the opportuniny to stabilize highly coherent lasers of the optical frequency of the hundreds of THz. This way a new standart of the time or optical frequencies called „Optical atomic clock“ can be defined. Institute of the Scientific Instruments in Brno in the cooperation with the Department of the Optics of the Palacky University in Olomouc implemented a unique research infrastructure for laser cooling of 40Ca+ ions and subsequent experiments of the quantum mechanics and spectroscopy in a joint laboratory in Brno. Currently 40Ca+ ions are routinely generated and captured. The Doppler cooling of those ions is performed using dipole transition at a wavelength of the 397 nm. Also detection and spectroscopy of the electronic structure of the ion and the presence of his dark resonances is implemented.\n
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Automatic system for gauge blocks calibration optimized for legal length metrology
Buchta, Zdeněk ; Šarbort, Martin ; Čížek, Martin ; Hucl, Václav ; Řeřucha, Šimon ; Pikálek, Tomáš ; Dvořáčková, Š. ; Dvořáček, F. ; Kůr, J. ; Konečný, P. ; Lazar, Josef ; Číp, Ondřej
This paper presents a contactless system for automatic and contactless gauge blocks calibration based on combination of laser interferometry and low-coherence interferometry. In the presented system, the contactless measurement of the absolute gauge block length is done as a single-step operation without any change in optical setup during the measurement. The optical setup is combined with compact gauge block changer with capacity 126 gauge blocks, which makes the resulting system fully automatic. \nThe paper also presents in detail a set of optimization steps which have been done in order to transform the original experimental setup into the automatic system which meets legal length metrology requirements. To prove the measurement traceability, we conducted a set of gauge block length measurement comparing data from the optimized system and the established reference system and TESA–UPC operated in Czech Metrology Institute laboratory.
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Calibration and linearization of an RTD sensor
Hucl, Václav ; Šedivá, Soňa (referee) ; Beneš, Petr (advisor)
First part of this work is focused on the description exist method of analogue and digital calibration and linearization static parameters resistance sensors. Second part deal with concrete problem linearization thermistor NTC by multivibrator compound of two transistors same polarity and multivibrator, where active element is operational amplifier. Last part of bachelor work is devoted digital linearization based on curve fitting and linearization based on piecewise-linear interpolation, their using with thermistor NTC and comparison their attributes.
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SMV-2015-38: Theoretical study of laser source for precise optical frequencies distribution
Hrabina, Jan ; Pravdová, Lenka ; Čížek, Martin ; Pham, Minh Tuan ; Hucl, Václav ; Řeřucha, Šimon ; Číp, Ondřej
The contractual project was oriented to theoretical study of design of ultra-stable laser source for precise optical frequencies long-range distribution through standard telecom optical fiber links. The research included theoretical investigation of possible optical setup arrangements with selection of optimal spectroscopy methods for the laser source frequency stabilization, special care was taken about ultra-high coherence of the laser needed for long-range distribution of the transmitted signals (hundreds of kilometers long links). The stabilization method was selected with respect to metrological traceability of the intended applications. The proposed optical system was compared to up-to-date available laser sources working at other wavelengths and crucial spectral and frequency stability parameters were summarized and compared. Proposed laser spectroscopy method and optical setup was experimentaly evaluated at laboratory environmental conditions and resulted stability/spectral parameters were summarized.
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Frequency stabilization of DBR diode laser working on 633 nm for lenght metrology and spectroscopy
Pham, Minh Tuan ; Hucl, Václav ; Čížek, Martin ; Mikel, Břetislav ; Hrabina, Jan ; Řeřucha, Šimon ; Lazar, Josef ; Číp, Ondřej
Semiconductor lasers are nowadays very convenient and suitable for many applications in field of human activities. Mainly it is thanks to their small size, low cost and high energy efficiency. This work deals with frequency stabilization of DBR diode laser working on 633 nm and the measurements of its noise properties. For this purpose we have chosen DBR diode EYP-DBR-0633 from Eagleyard Photomic. This particular laser diode in temperature range from 6 degrees celsius to 24 degrees Celsius has a tuning range of 0,86 nm, which correspond to change of 650 GHz in optical frequency domain. In this paper we also present methodology and results for frequency noise properties investigation of this laser with unbalanced Mach-Zhender interferometer and 10 m long fibre spool inserted in reference arm.
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Digital signal synthesizer for compensating Doppler effect in fiber-optic lines
Hucl, Václav ; Čížek, Martin ; Pham, Minh Tuan ; Pravdová, Lenka ; Číp, Ondřej
If a highly stable laser standard is distributed over a long fiber-optic line the stability of optical frequency of the laser at the far end is usually degraded due to external influences on the optical fiber. Thermal dilatation or vibrations of the fiber result in Doppler shifts changing the optical frequency of the laser light. A setup based on an unbalanced Mach-Zehnder or a Michelson interferometer with the optical line acting as a measuring arm can be used for detecting Doppler frequency shifts. Once we are able to detect the shifts we can compensate them by detuning the optical frequency of the transmitted laser light in a closed-loop. Our paper presents the method of detecting the frequency shifts in the fiber-optic line together with a digital electronic controller. The controller is based on a digital signal processor and a DDS chip for generating the radiofrequency signal driving the acousto-optic modulator in order to detune the transmitted laser light.
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