Metrological Problems Research Articles (Page 3)

Advances in ultrashort pulse lasers and spectral manipulation enable new approaches to metrological problems in various fields. Dimensional metrology may benefit particularly from this progress, including applications like long distance measurement and 3D laser scanning. Using the intermode beat notes obtained by direct photodetection of a mode-locked femtosecond laser has been demonstrated as a promising alternative to solutions based on actively modulated signals. In this work, we extend the approach to ultra-broadband sources derived from femtosecond lasers, aiming at investigating their potential as a technological basis for multiwavelength distance metrology. We have developed a short-distance experimental set-up for displacement measurement operating simultaneously at two wavelength ranges on both extremes of a 500 nm coherent supercontinuum. The results derived from the phases of the 1 GHz intermode beat notes show that the internal coherence of the source is sufficient to derive distances with an accuracy better than 50 μm. This is a promising first step for the prospective application of this method to develop spectrally-versatile solutions, which is of interest to provide surface material probing capabilities in laser scanning and to increase the accuracy of long distance measurement though dispersion-based refractivity compensation.

The modern trend of most advanced countries is the active development and implementation of Industry 4.0 technologies, Internet of things and “smart cities”. Despite the “autonomy” of these technologies, they still remain dependent on the achievements of metrology. The article deals with the concept of cyber-physical systems, presents an analysis of the problems of their metrological support, and shows the main metrological problems in the development of these technologies.

Problems related to the use of the concept of measurement uncertainty in different types of metrological problems, such as calibration, type evaluation, and the verification of measuring instruments are considered. A classification of risks in the assessment of the correspondence of measuring instruments to specific requirements is presented. Examples of conformity decision rules used in verification of measuring instruments are presented and the role of measurement uncertainty in these rules is demonstrated.

Metrological problems that arise in measurements of the temperature of physical objects by means of pyrometers, where the emissivity of the objects is different from 1 and may vary with a variation in the wavelength, are considered. Factors are established and methods of eliminating inaccuracies in the radiation coefficient of energy-controlled pyrometers are presented. Violations in the traceability of pyrometers with built-in correction units relative to the state primary standard of the unit of temperature are discussed and recommendations for recovering traceability are presented.

Construction of the new gas meter high pressure calibration facility – Technical and metrological problems

One of the main problems of modern measurement technology and Metrology is that no non-destructive testing device, due to its design features, allows to make metrological measurements necessary for the construction of a three-dimensional geometric model of the part surface, which is a superposition of the geometric image of the surface and the topography of its microrelief. As a rule, in the calculation of the forming surface of the tool there is no calculation of the topography of its microrelief. This is due to the lack of sufficient information about the geometric structure of the microrelief as a three-dimensional image, due to the use of one-dimensional evaluation parameter. Application for geometric modeling of the microrelief shape of a one-dimensional evaluation parameter-the height of the microrelief, gives an idea of the microrelief as a surface with numerical marks. In the description of the surface with numerical marks, the curvature in the local neighborhood of the given point is not determined, which makes it impossible to construct its full geometric image. The solution to the problem is to create a non-destructive testing device-an optical profilograph, the design of which would allow to measure the geometric characteristics of the surface of the part necessary for structuring its full geometric image and the development of a new geometric approach that allows to obtain this complete geometric image of the part. Installation - optical profilograph refers to measuring equipment, in particular to devices for roughness control. This installation is designed as a complex of non-destructive testing devices of new generation, which is aimed at solving the actual problem in the conduct of metrological measurements required to build a three-dimensional geometric model of the surface of the part, which would be a superposition of the geometric image of the surface of the part and the topography of its microrelief. The principle of operation of the installation is that the holographic image of the part, the scanning indicator of the electromagnetic field are removed cards, which are fixed microrelief profiles of the surface layer, profiles of internal and external surfaces of the part. With these profiles remove the geometric characteristics, which are based on the modular geometric approach allows you to structure the topography of the surface layer microrelief, as well as the internal and external geometry of the surfaces of the part, having a complex shape.

Metrological problems of modern energy pyrometry

The requirements imposed on vertical-cavity surface-emitting lasers in a number of metrological problems in which optical pumping of alkali atoms is used are considered. For lasers produced by different manufacturers, these requirements are compared with the experimentally observed spectral characteristics at a constant pump current and in the microwave modulation mode. It is shown that a comparatively small number of lasers in the microwave modulation mode make it possible to obtain the spectrum required for atomic clocks based on the coherent population-trapping effect.

Abstract The requirements imposed on vertical-cavity surface-emitting lasers in a number of metrological problems in which optical pumping of alkali atoms is used are considered. For lasers produced by different manufacturers, these requirements are compared with the experimentally observed spectral characteristics at a constant pump current and in the microwave modulation mode. It is shown that a comparatively small number of lasers in the microwave modulation mode make it possible to obtain the spectrum required for atomic clocks based on the coherent population-trapping effect.

Metrological problems of modern energy pyrometry

Polarization metrology is gaining increased importance as polarized light is recently involved in different branches of science and technology. This paper summarizes the contributions of the optical polarization laboratory at the National Institute for standards (NIS, Egypt) during the last 25 years. These include introducing a new class of total internal reflection phase retarders, modifying the Senarmont method to allow for simultaneous calibration of two phase plates at any wavelength, birefringence measurements, applications of the Poincare sphere, calibration and adjustment of polarization elements and measurements of the optical constants of conductors.

Certain aspects of metrological assurance of building materials moisture metering are presented. Verification of dielcometric hydrometers using reference materials is considered. The advantages and drawbacks of sample simulators and reference materials based on natural substances are demonstrated. A broad range of standard samples and sample simulators is created in order to improve the system of metrological assurance of the building materials branch and regulatory documents that define the methods and means of verification of the moisture meters used with building materials are developed.

<p class="Abstract"><span lang="EN-US">In electrical quantities metrology numerous examples of stochastic processes exist and a need for optimal solutions is posed. Here stochastic genetic algorithm optimization is used for solving two typical metrological problems: 1) minimization of the metrological parameters (final accuracy) in the design process of instruments and 2) predicting metrological reference standard’s time-drift, i.e. re-calibration interval. The first case is the optimal metrological design of a combined instrument transformer and the second case is the analysis of resistance standard time-drift.</span></p>

Metrology and scientific and technological progress are inextricably linked, since, on the one hand, without the precise measurements it is impossible to develop science, and on the other hand, the very achievements of science and technology stimulate the development of measuring techniques, the emergence of new methods and means for determining various physical quantities . Due to this interconnection, the urgent tasks of modern metrology necessarily have to be tasks, the solution of which ensures progress in all spheres of human activity, including science, technology and technology, ecology, social relations, etc. The report discusses the current problems of metrology due to the transition to the third stage of the industrial revolution, the development of additive and information technology, nanotechnology. The approaches of countries with developed scientific and technical and economic potential to solve these problems are analyzed.

On the theory of simultaneous retardance measurement of two phase plates

Metrological problems associated with the measurement of dynamic load vector parameters in systems with three single-component vibration sensors are examined. Sources of dynamic error and false precession of the obtained vector are analyzed while using analog and digital measurement systems. A package of tasks has been developed to correct amplitude and phase distortions while measuring vector parameters of nonsteady-state dynamic loads.

We derive a computable analytical formula for the quantum fidelity between two arbitrary multimode Gaussian states which is simply expressed in terms of their first- and second-order statistical moments. We also show how such a formula can be written in terms of symplectic invariants and used to derive closed forms for a variety of basic quantities and tools, such as the Bures metric, the quantum Fisher information, and various fidelity-based bounds. Our result can be used to extend the study of continuous-variable protocols, such as quantum teleportation and cloning, beyond the current one-mode or two-mode analyses, and paves the way to solve general problems in quantum metrology and quantum hypothesis testing with arbitrary multimode Gaussian resources.

Актуальные проблемы технического регулирования и метрологического обеспечения

- Zagadnienia metrologiczne badań eksperymentalnych urządzeń spawalniczych. Cz. 1. Błędy i niepewności w pomiarach prądu, napięcia i mocy z zastosowaniem czujników hallotronowych

Wavelength-scanned cavity ring-down spectroscopy (WS CRDS) is used in gas analysis. Calibration gas mixtures containing carbon monoxide, carbon-12 dioxide, carbon-13 dioxide, methane, and formaldehyde are used to determine the metrological characteristics of WS CRDS gas analyzers. Most experimental results are in agreement with the declared data. For gas mixtures in which the gas matrix differs from air, the broadening of spectral lines related to the interaction of particles causes significant errors in the concentration measurements. Such effects that neutralize the advantages of the WS CRDS method are studied in this work. The coefficients that can be used to correct the results of the WS CRDS gas analyzers and compensate for errors related to different gas matrices are presented.