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  • 1.
    Ebenhag, Sven-Christian
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Zelan, Martin
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Hedekvist, Per Olof
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Karlsson, Magnus
    Chalmers University of Technology, Sweden.
    Implementation of an optical fiber frequency distribution via commercial DWDM2016In: 2016 IEEE International Frequency Control Symposium (IFCS), 2016, article id 7563586Conference paper (Refereed)
    Abstract [en]

    The rapid development in communication infrastructure over the past decades entails an increasing dependence on time and frequency, as well as its redundant distribution. This places demands not only on already existing distribution methods, but also on the development of new ones to meet future needs. To meet these demands several research groups are working on high performance fiber-based frequency transfer techniques. The best achieved performance so far is the techniques using a single bi-directional fiber connection, with customized bi-directional optical amplifiers [1]. The objective of this project is to develop a method that is compatible with data communication in DWDM-systems, i.e. using the existing infrastructure, as well as to be complementary technique for time and frequency distribution. Even though it is likely to have worse performance than the bi-directional system in terms of frequency stability, it will allow for the impassable obligation to follow the deployed structure of telecom networks. The establishment and early results of the non-stabilized link has been previously presented [2, 3]. The ongoing evaluation and improvement will be aimed at finding relevant performance specifications for a connection using this technique. The work presented here is the most recent results of the frequency transfer and discusses the future plans for the fiber connection, including the added time transfer method. If proven successful, the long-term objective is to establish a distribution network for optical frequency references in Sweden.

  • 2.
    Pendrill, Leslie
    et al.
    RISE - Research Institutes of Sweden, Safety and Transport, Measurement Science and Technology.
    Zelan, Martin
    RISE - Research Institutes of Sweden, Safety and Transport.
    Det nya internationella måttsystemet: – tid för ett nytt måttsystem2017Report (Other (popular science, discussion, etc.))
    Abstract [sv]

    Idag kan alla måttenheter härledas från SI-systemets sju basenheter (meter, kilogram, sekund, kelvin, candela, ampere, mol). Genom nya forskningsframsteg planeras nu en reformering av SI-systemet. Förändringen förväntas att bli beslutad 2018, och forskare på alla länders olika Nationella Metrologiinstitut jobbar nu med förberedelserna för att införa det nya SI-systemet.

  • 3.
    Silander, Isak
    et al.
    Umeå University, Sweden.
    Hausmaninger, Thomas
    Umeå University, Sweden; VTT, Finland.
    Forssén, Clayton
    Umeå University, Sweden.
    Zelan, Martin
    RISE - Research Institutes of Sweden, Safety and Transport, Measurement Science and Technology.
    Axner, Ove
    Umeå University, Sweden.
    Gas equilibration gas modulation refractometry for assessment of pressure with sub-ppm precision2019In: Journal of Vacuum Science and Technology B: Nanotechnology and Microelectronics, ISSN 2166-2746, E-ISSN 2166-2754, Vol. 37, no 4, article id 042901Article in journal (Refereed)
    Abstract [en]

    Gas modulation refractometry (GAMOR) is a methodology that, by performing repeated reference assessments with the measurement cavity being evacuated while the reference cavity is held at a constant pressure, can mitigate drifts in dual Fabry-Perot cavity based refractometry. A novel realization of GAMOR, referred to as gas equilibration GAMOR, that outperforms the original realization of GAMOR, here referred to as single cavity modulated GAMOR (SCM-GAMOR), is presented. In this, the reference measurements are carried out by equalizing the pressures in the two cavities, whereby the time it takes to reach adequate conditions for the reference measurements has been reduced. This implies that a larger fraction of the measurement cycle can be devoted to data acquisition, which reduces white noise and improves on its short-term characteristics. The presented realization also encompasses a new cavity design with improved temperature stabilization and assessment. This has contributed to improved long-term characteristics of the GAMOR methodology. The system was characterized with respect to a dead weight pressure balance. It was found that the system shows a significantly improved precision with respect to SCM-GAMOR for all integration times. For a pressure of 4303 Pa, it can provide a response for short integration times (up to 10 min) of 1.5 mPa (cycle)1/2, while for longer integration times (up to 18 h), it shows an integration time-independent Allan deviation of 1 mPa (corresponding to a precision, defined as twice the Allan deviation, of 0.5 ppm), exceeding the original SCM-GAMOR system by a factor of 2 and 8, respectively. When used for low pressures, it can provide a precision in the sub-mPa region; for the case with an evacuated measurement cavity, the system provided, for up to 40 measurement cycles (ca. 1.5 h), a white noise of 0.7 mPa (cycle)1/2, and a minimum Allan deviation of 0.15 mPa. It shows a purely linear response in the 2.8-10.1 kPa range. This implies that the system can be used for the transfer of calibration over large pressure ranges with exceptional low uncertainty. © 2019 Author(s).

  • 4.
    Silander, Isak
    et al.
    Umeå University, Sweden.
    Hausmaninger, Thomas
    Umeå University, Sweden.
    Zelan, Martin
    RISE - Research Institutes of Sweden, Safety and Transport, Measurement Science and Technology.
    Axner, Ove
    Umeå University, Sweden.
    Gas modulation refractometry for high-precision assessment of pressure under nonerature-stabilized conditions2018In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 36, no 3, article id 03E105Article in journal (Refereed)
    Abstract [en]

    The authors report on the realization of a novel methodology for refractometry - GAs modulation refractometry (GAMOR) - that decreases the influence of drifts in Fabry Perot cavity refractometry. The instrumentation is based on a dual Fabry-Perot cavity refractometer in which the beat frequency between the light fields locked to two different cavities, one measurement and one reference cavity, is measured. The GAMOR methodology comprises a process in which the measurement cavity sequentially is filled and evacuated while the reference cavity is constantly evacuated. By performing beat frequency measurements both before and after the finite-pressure measurement, zero point references are periodically created. This opens up for high precision refractometry under nontemperature-stabilized conditions. A first version of an instrumentation based on the GAMOR methodology has been realized and its basic performance has been scrutinized. The refractometer consists of a Zerodur cavity-block and tunable narrow linewidth fiber lasers operating within the C34 communication channel (i.e., around 1.55 μm) at which there are a multitude of fiber coupled off-the-shelf optical, electro-optic, and acousto-optic components. The system is fully computer controlled, which implies it can perform unattended gas assessments over any foreseeable length of time. When applied to a system with no active temperature stabilization, the GAMOR methodology has demonstrated a 3 orders of magnitude improvement of the precision with respect to conventional static detection. When referenced to a dead weight pressure scale the instrumentation has demonstrated assessment of pressures in the kilo-Pascal range (4303 and 7226 Pa) limited by white noise with standard deviations in the 3.2 N - 1 / 2 - 3.5 N - 1 / 2 mPa range, where N is the number of measurement cycles (each being 100 s long). For short measurement times (up to around 103 s), the system exhibits a (1 σ) total relative precision of 0.7 (0.5) ppm for assessment of pressures in the 4 kPa region and 0.5 (0.4) ppm for pressures around 7 kPa, where the numbers in parentheses represent the part of the total noise that has been attributed to the refractometer. As long as the measurement procedure is performed over short time scales, the inherent properties of the GAMOR methodology allow for high precision assessments by the use of instrumentation that is not actively temperature stabilized or systems that are affected by outgassing or leaks. They also open up for a variety of applications within metrology; e.g., transfer of calibration and characterization of pressure gauges, including piston gauges. 

  • 5.
    Zelan, Martin
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik, Massa, kraft, längd och tryck.
    En ny sekunddefinition - en tidsfråga2014In: Fysikaktuellt, no 3, p. 8-9Article in journal (Other (popular science, discussion, etc.))
  • 6.
    Zelan, Martin
    RISE - Research Institutes of Sweden, Safety and Transport, Measurement Science and Technology.
    Gas Modulation Refractometry for High-Precision Assessment of Pressure under Non-Temperature-Stabilized Conditions2018Conference paper (Other academic)
  • 7.
    Zelan, Martin
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik, Massa, kraft, längd och tryck.
    Arrhén, Fredrik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik, Massa, kraft, längd och tryck.
    Jarlemark, Per
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik, Kommunikation.
    Mollmyr, Oscar
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik, Massa, kraft, längd och tryck.
    Johansson, Håkan
    Simea Optics AB, Sweden.
    Characterization of a fiber-optic pressure sensor in a shock tube system for dynamic calibrations2015In: Metrologia, ISSN 0026-1394, E-ISSN 1681-7575, Vol. 52, no 1, p. 48-53Article in journal (Refereed)
    Abstract [en]

    Measurements of mechanical quantities such as pressure often take place under dynamic conditions, yet no traceable standards for the primary dynamic calibration of pressure sensors currently exist. In theory, shock tubes can provide a close to perfect step-function ideal for the calibration of pressure transducers. In this paper we investigate a system consisting of a shock tube and an ultra-fast fiber-optical sensor that is designed to be a future primary system for dynamic pressure calibrations. For reference, the fiber-optical sensor is compared to a piezoelectric sensor, and their corresponding frequency spectra are calculated. Furthermore, an investigation of the repeatability of the fiber-optical sensor, as well as a comparison with a second shock tube, is performed.

  • 8.
    Zelan, Martin
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik, Massa, kraft, längd och tryck.
    Arrhén, Fredrik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik, Massa, kraft, längd och tryck.
    Pendrill, Leslie
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik.
    Foltynowicz, Aleksandra
    Silander, Isak
    Axner, Ove
    Optical measurement of the gas number density in a Fabry–Perot cavity2013In: Meas. Sci. Technol., Vol. 24, p. art nr 105207-Article in journal (Other academic)
    Abstract [en]

    An optical method for measuring the gas density by monitoring the refractive index inside a high-finesse Fabry–Perot cavity is presented. The frequency of a narrow linewidth Er:fiber laser, locked to a mode of the cavity, is measured with the help of an optical frequency comb while the gas density inside the cavity changes. A resolution of 1.4 × 10-6 mol m-3 is achieved in 3 s for nitrogen, which allows measurement of a relative gas density change of 3.4 × 10-8 at atmospheric pressure.

  • 9.
    Zelan, Martin
    et al.
    RISE - Research Institutes of Sweden, Safety and Transport, Measurement Science and Technology.
    Pendrill, Leslie
    RISE - Research Institutes of Sweden, Safety and Transport, Measurement Science and Technology.
    Vikten av ett nytt kilogram2018In: Fysikaktuellt, no 3, p. 16-17Article in journal (Other (popular science, discussion, etc.))
1 - 9 of 9
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