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Measure Articles 2012 (19)

 
Picture of the productA Multi-Sensor Approach for Complex and Large-Area App.
Eberhard Manske, Gerd Jager and Tino Hausotte
In micro and nanotechnology, the metrological demands are increasing. The structures to be measured are becoming more complex with smaller structure widths, increasingly larger surface regions, and thousands of inspection features. In order to solve the problems, it has become desirable and even necessary to combine multi-sensor technology with high precision nanopositioning and nanomeasuring technology. The Nanopositioning and Nanomeasuring Machine NMM-1 with a measuring range of 25 mm × 25 mm × 5 mm and sub-nanometer resolution allows the application of several optical, tactile and atomic force probes. The combination of several sensor technologies in a multi-sensor approach for application with the NMM-1 is demonstrated.


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MS12_02_MANSKE
Picture of the productA Sub-Sampling Digital PM/AM Noise Measurement System
Craig W. Nelson and David A. Howe
A digital phase/amplitude modulation (PM/AM) noise measurement system (DNMS) implementing field programmable gate array (FPGA) based digital down converters (DDCs), and 250 MHz analog to digital converters (ADCs) is reported. Measurements in the first, baseband Nyquist region shows white phase noise floors of less than -180 dBc/Hz. With proper prefiltering of the input signals to prevent undesired aliasing, high bandwidth track and hold amplifiers (THA) extend the operating range of the DNMS to microwave frequencies. Preliminary testing with an 18 GHz THA shows residual white phase noise floors at 10 GHz of less than -160 dBc/Hz.


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MS12_03_NELSON
Picture of the productArmy Primary Standards Laboratory Uncertainty Analysis
Wesley B. England
This paper is a detailed uncertainty analysis for a 50 gallon per minute (gpm) positive displacement piston prover operated by the Liquid Flow Laboratory of the Army Primary Standards Laboratory (APSL). This uncertainty analysis encompasses all known contributors included in the APSL estimation of liquid flow piston prover uncertainty, including connecting volume and viscosity. This uncertainty analysis is intended as an aid to those who work in the field of liquid flow metrology.


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MS12_04_ENGLAND
Picture of the productCalculation of Dual Circle Closure Calibrations using Comp.
Hy D. Tran
This technical note will detail a procedure for simultaneous calibration of two rotary devices by circle closure, along with the necessary calculations. These calculations can be implemented using numerical analysis software, or with computer spreadsheets. We first detail an example procedure for a dual closure for two rotary tables with six sectors, and then provide a detailed derivation of the mathematics.


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MS12_01_TRAN
Picture of the productCharacterization of Triangulation-Based 3D Imaging Systems
Jean-Angelo Beraldin, Benjamin Carrier, David MacKinnon, and Luc Cournoyer
A set of test procedures and certified artifacts to characterize the capability of short-range triangulation-based threedimensional (3D) imaging systems are presented. The approach consists of scanning metallic and coated-glass certified artifacts in which the uncertainties in the associated characteristic reference values are smaller than the measurement uncertainties produced by the system under test (SUT). The artifacts were grouped on the same plate for portability. To define a set of test procedures that is practical, simple to perform and easy to understand, we utilized a terminology that is well-known in the manufacturing field, i.e., geometric dimensioning and tolerancing (GD&T). The National Research Council Portable Characterization Target (NRC-PCT) is specifically designed for the characterization of systems with depths of field from 50 mm to 500 mm. Tests were performed to validate the capability of the NRC-PCT. This paper presents these results, along with some basic information on 3D imaging systems.


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MS12_04_BERALDI
Picture of the productCircuits for the Calibration of Quartz & Mech. Watch Testers
Cho-man Tsui and Hon-man Chan
Watch testers offer a fast and accurate way to calibrate stopwatches using the time base method. Watch testers usually include microphone sensors that pick up either the ultrasound from quartz oscillators or the acoustic vibration from balance wheels, and instrumentation that measures the accuracy of these frequencies. As a laboratory instrument, the watch tester itself requires calibration. Two simple circuits have been developed to generate the acoustic signals for the calibration of quartz and mechanical watch testers, respectively. The reference frequency is obtained from a signal generator phase locked to the laboratory frequency standard. It is assumed that the laboratory frequency standard has been calibrated, has a known measurement uncertainty, and that metrological traceability to the International System (SI) second has been established.


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MS12_04_TSUL
Picture of the productDevelopment of High-Stability Metal-Foil Standard Resistors
Nobu-hisa Kaneko, Takahiko Oe, Atsusi Domae, Takayuki Abe, Masaya Kumagai, and Matsuo Zama
Compact metal-foil standard resistors with four terminals have been developed. The main DC characteristics of the developed 100 Ω resistors are a drift rate of <0.1 (µΩ/Ω)/year, a temperature coefficient of <0.1 (µΩ/Ω)/ºC at 23 ºC, changes in resistance due to humidity that are negligible or lower than 0.01 (µΩ/Ω) in the 35 % RH to 80 % RH range, and changes in resistance versus the pressure variation that are negligible or lower than 0.025 (µΩ/Ω)/(250 hPa) in the 700 hPa to 1200 hPa range. The power coefficient is negligible based on the quantized Hall resistance when the applied current is lower than 5 mA. The AC performance was also characterized: the frequency dependence is negligible below 2 kHz, and the time constant is 3.7 ns. These excellent characteristics have been achieved by careful optimization of the composition, annealing conditions, and surface treatment of the element materials, and also by a strain-free supporting technique for the resistor elements. The development of the 100 Ω resistors has been completed, and 1 Ω to 10 kΩ resistors are now being developed. Preliminary results for the 10 Ω resistors show a drift rate similar to that of the 100 Ω resistors.


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MS12_04_KANEKO
Picture of the productEconomic Impact of Equivalence of Measure Standards
Takashi Usuda and Andy Henson
This paper discusses a new method for estimating the economic impact of the equivalence of measurement standards. The method allows a quantitative calculation of the economic impact, based on a distribution function describing the quality of the product and information about the agreement of measurement standards. In particular, the proposed method considers loss parameters (false positive, false negative, and loss function) due to the deviation of measurement standards. The method can be applied to any industry, any market, and to users at any level of the calibration hierarchy. We illustrate the method with an example that demonstrates the economic impact of inconsistencies in a mass measurement standard due to the quality distribution of weighing instruments. The example shows that the current system of assuring the equivalence of measurement standards is effective and delivers significant benefits. It also demonstrates the importance of information about the agreement of measurement standards when assessing their economic impact.


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MS12_01_USUDA
Picture of the productEstablishing Traceability for Quantities Derived from Mult.
Jian Liu and Alberto Campillo
Some quantities are traceable to a single quantity with the same unit but a lower uncertainty. For instance, a weight of 50 g ± 1 g might be calibrated with a reference weight of 50 g ± 0.1 g. Meanwhile, other quantities are calibrated by using multiple quantities with different units as references. A simple example would be measuring DC current with a volt meter and a standard resistor. In this case, the current measurement is derived from DC voltage and resistance. A more complicated example of a derived quantity is phase noise. The question is: how do we establish traceability for such derived quantities? This paper discusses the International System of Units (SI), base and derived quantities, and traceability; and presents a general approach for establishing traceability for a quantity that is derived from multiple traceable quantities. The traceability of phase noise measurements is then considered as an example, based upon two common measurement techniques that utilize a spectrum analyzer and a phase detector.


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MS12_02_LIU
Picture of the productExperimental Study and Computer Modeling of the Triple Point
R. Ding, M.J. Zhao, T. Nielson, E. Nerdrum, and D. Farley
The triple point of argon is a defined fixed point in ITS-90 for calibration of standard platinum resistance thermometers (SPRTs). A new triple point of argon system with multiple re-entrant wells was developed. This system was tested to evaluate the duration and quality of the argon triple-point temperature plateau. The testing results showed that the plateau can be as long as 100 hours with the temperature change less than 0.05 mK. The re-entrant wells’ uniformity testing showed that the temperature is consistent among the multiple re-entrant wells. Uncertainty analysis shows that the combined uncertainty of the argon system is 0.26 mK (k = 2). In order to study the heat transfer process and the influence on the thermal equilibrium of the argon system during the realization of the triple-point of argon plateau, finite element analysis (FEA) modeling was carried out to simulate the thermal conductivity, convection, and radiation inside the argon system. The FEA simulation results are described and discussed in this paper.


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MS12_01_DING
Picture of the productHigh Accuracy Measurements Using a Scanning System
Ted Doiron, Wei Ren, Eric Stanfield, Bala Muralikrishnan, and Christopher Blackburn
The capabilities of non-contact laser spot triangulation sensors for high accuracy measurements have slowly increased over the past decade, and now have usable resolution below 0.1 μm. The Dimensional Metrology Group at the National Institute of Standards and Technology (NIST) has developed a simple scanning system to work with these sensors, and presents the system details and data from a variety of geometries. The features measured include screw threads, fuel cell channels, and computer tomographic (CT) scanner phantoms.


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MS12_04_DOIRON
Picture of the productHigh Level Humidity Generator for Nitrogen-Water Mixtures
Peter Huang, Wyatt Miller, and Gregory Strouse

A high level humidity generator has been developed at the National Institute of Standards and Technology (NIST). This device provides the capability for research, testing and calibration at high levels of water vapor content in such gases as hydrogen, nitrogen, and ambient air for applications such as hydrogen-powered fuel cells, standard reference materials and food processing. The generator produces a gas stream of nitrogen-water vapor mixture having mixing ratios from 0.16 g to 1.47 g of water vapor per gram of dry nitrogen (g H2O/g dry N2). This is equivalent to dew point temperatures of 60 °C to 90 °C at standard atmospheric pressure and to water vapor pressures of 19 948 Pa to 70 182 Pa. The generated gas can be fed to a test chamber with independent temperature control from 25 °C to 200 °C and pressure control from 0.1 MPa to 1.5 MPa, for the calibration of hygrometers. Inter-comparisons with a NIST reference standard dew point hygrometer gave results that in all cases agreed to within 0.014 g H2O/g dry N2.



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MS12_02_HUANG
Picture of the productNorth American 100 Ampere Interlaboratory Comparison
Jay Klevens
The base SI unit for electricity is the ampere. At present, there is no intrinsic standard for the ampere, so in practice it is disseminated by measuring voltage across a resistor, using Ohm’s Law (I = E / R). Higher current is measured with a shunt, which is a high power resistor. Accurate electrical current measurement is critical to the power and electrical test industries. In cooperation with the National Institute of Standards and Technology (NIST) and the NCSLI Utilities Committee, Ohm-Labs performed a North American 100 ampere interlaboratory comparison (ILC). Many measurements did not meet claimed uncertainties, revealing errors in measurement and uncertainty estimation. Two rounds of measurements were performed, and the results of both rounds are presented in this paper.


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MS12_03_KLEVENS
Picture of the productPrecise Blackbody Sources Developed at VNIIOFI
Sergey Ogarev, Boris Khlevnoy, Boris Lislansky, Svetlana Morozova, Mikhall Samoylov, and Victor Sapritsky
This paper reviews a wide list of precise blackbody (BB) sources developed at the All-Russian Research Institute for Optical and Physical Measurements (VNIIOFI). These radiometric, photometric and radiation thermometry standards are for the entire UV-visible-IR spectrum, and cover the temperature range from 80 K to 3500 K [1, 2, 3]. Low temperature blackbodies with temperatures from cryogenic to 450 K were developed for space borne instruments calibration [4, 5, 6]. We present models of variable-temperature BBs, as well as those based on fixed-points of Ga, In and binary metal-metal eutectic alloys. BBs are characterized with high temperature uniformity and stability. For example, for the BB100-V1 model, these parameters account for 0.05 K to 0.1 K, and 0.1 % for the 1.5 ìm to 15 ìm wavelength region under cryo-vacuum conditions of medium background environment emulating the orbital working environment. Copper and aluminum alloys are used as the radiation cavity materials for the low-temperature and cryogenic BBs. Recent advances in high-temperature technology and a novel design made it possible to develop the Planckian sources with temperatures as high as 3500 K, high uniformity, and stable radiation characteristics [7, 8, 9]. These large-area blackbodies allow the creation of a new generation of radiometric and radiance temperature standards with low uncertainties. High-temperature, large aperture blackbodies of the BB3500 series allow the realization of projects requiring high-temperature fixed points based on metal-carbon eutectic and peritectic alloys.


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MS12_03_OGAREV
Picture of the productProficiency Testing Program for U.S. State Weights and Meas.
Elizabeth Gentry, Georgia Harris, and Val Miller
The National Institute of Standards and Technology (NIST) Office of Weights and Measures (OWM) manages a State Laboratory Program for weights and measures laboratories that includes: 1) Laboratory recognition using ISO/IEC 17025:2005 and sponsorship of accreditation through the National Voluntary Laboratory Accreditation Program (NVLAP); 2) Hands-on training courses held at NIST, regional measurement assurance program (RMAPs) training held annually throughout the United States, and a number of web-based short courses; and 3) Formal proficiency testing and interlaboratory comparisons (PT/ILC). The main objective of the State Laboratory Program is to ensure nationally consistent measurement results, acceptable accuracy and metrological traceability, and the credibility and acceptance of state laboratory measurements. This paper presents the key features of the PT/ILC program: measures of success; collaboration challenges; the use of template tools; and continual improvement efforts. Note that while most interlaboratory comparisons are also proficiency tests, some are not. For simplicity, however, this paper will refer to the PT/ILC effort as the PT program.


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MS12_02_GENTRY
Picture of the productRisk Mitigation Strategies for Compliance Testing
Jonathan Harben and Paul Reese
Many strategies for risk mitigation are now practiced in calibration laboratories. This paper presents a modern look at these strategies in terms of compliance to ANSL/NCSLI and ISO standards. It distinguishes between “Bench Level” and “Program Level” risk analysis techniques, which each answer different questions about risk mitigation. It investigates concepts including the test uncertainty ratio (TUR) and end of period reliability (EOPR) that are directly related to risk, as well as the mathematical boundary conditions of false accept risk to gain a comprehensive understanding of practical, efficient risk mitigation. The paper presents practices and principals that can allow a calibration laboratory to meet the demand of customers and manage risk for multifunction instrumentation, while complying with national and international standards.


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MS12_01_HARBEN
Picture of the productSensors for Optical 3D Measurements of Micro Geometries
Holger Bremer, Ulrich Neuschaefer-Rube, and Thomas Birth This paper provides an overview of some of the optical measurement techniques for dimensional measurements of surface topographies. These techniques are used in laboratories, as well as close to the production line. The principles of white light interferometry, focus variation, fringe projection, confocal microscopy, and image processing will be addressed. Examples of typical applications will be given and some of their benefits and limitations discussed.

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MS12_02_BREMER
Picture of the productSoftware Tools for Eval. of Measurement Models to The GUM
Cho-man Tsui, Aaron Y. K. Yan, and Hing-wah Li
In October 2011, a new guidance document “Evaluation of measurement data • Supplement 2 to the ´Guide to the expression of uncertainty in measurement’ • Extension to any number of output quantities” was released. It deals with measurement models that have more than one output quantity. These models are common in electrical metrology where the measurands can be complex-valued quantities, such as S-parameters. The guidance document described a generalized GUM Uncertainty Framework (GUF) and a Monte Carlo Method (MCM) to estimate the output quantities, their standard uncertainties, the covariances between them, and the coverage region. The GUF has more limitations. The MCM has a broader domain of validity but requires software tools for its computation. The Standards and Calibration Laboratory (SCL) in Hong Kong has developed software tools for evaluation of complex-valued measurement models using both GUF and MCM. The software tools were written in Visual C++ and Visual Basic, with Microsoft Excel as a front-end user interface, but could be adapted to other programming languages. The user is only required to encode the measurement model as a Visual Basic subroutine and to enter the information of the uncertainty components in a table. The software tool includes two parts that can be used separately, with the first part as a standalone simulator and the second part as an Excel user-defined function.


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MS12_03_TSUI
Picture of the productSpectrum Analyzer CW Power Meaurements
Francis Small
Spectrum analyzers are used in various applications to measure the power of an electrical signal, their frequency discrimination capability making them a key component in the electronic test and measurement industry. Although they do not have the same inherent amplitude accuracy as other measurement devices such as broadband power sensors [1], they have superior dynamic range that can extend in some cases to the environmental thermal noise limit. Previous work has described the theoretical model of spectrum analyzer power measurements in the presence of noise, but practical guidelines for actual measurements are less forthcoming. This paper examines how to configure a spectrum analyzer to measure a low-power continuous wave (CW) signal so that the trade-off between measurement time and accuracy is optimized. It presents equations describing both the bias and the variance of spectrum analyzer measurements due to noise.


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MS12_04_SMALL
Picture of the productTesting and Calibration of Phasor Measurement Units
Richard Pirret
In the evolving Smart Grid, time-variant sources and loads introduce disturbances that can threaten the stability of the grid. Sophisticated protection and control systems are required to preserve reliability. These systems rely on accurate, synchronous measurements of voltage, current and frequency made by Phasor Measurement Units (PMUs). Although PMUs first appeared in 1988, their recent deployment has exposed inconsistent measurements and poor interoperability across brands and models. However, several recent developments promise to enhance the accuracy and consistency of PMU measurements. IEEE C37.118.1:2011, “Standard for Synchrophasor Measurements for Power Systems”, established new performance limits for PMU test and calibration. The revised standard more clearly defines existing concepts, and enhanced and added material to the sections on steady state and dynamic tests. The emergence of automated systems supports the consistent execution of standard tests during PMU calibrations, and the observance of sound traceability practices for PMU ensures the accuracy of those calibrations. This paper describes the fundamentals of phasor measurements, the recent revisions to the IEEE C37.118.1 standard, a new automated PMU calibration system developed at Fluke, and the establishment of traceability for PMU calibrations.


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MS12_02_PIRRET
Picture of the productTraceability and Quality Control in a Radiation Thermometry
Frank Liebmann and Tom Kolat
In radiation thermometry, a number of steps have been taken to improve calibration quality at temperatures below 1000 °C. These steps involve work done by national metrology institutes and standards bodies. The Fluke Infrared Calibration Laboratory in American Fork, Utah has benefitted from this progress and has established its own radiation thermometry program. The calibration range of this laboratory is -15 °C to 500 °C. This program involves calibrating radiometric transfer standards (with pyroelectric detectors) that, in turn, are used to calibrate flat-plate radiation sources, sometimes referred to as blackbodies. The transfer standards are calibrated by a sequence of blackbody cavity radiation sources that cover the entire temperature range of the laboratory. The radiometric transfer takes place between the cavity sources and the flat-plate sources. The intended use of the flat-plate sources is infrared thermometer calibration. Both the transfer standard calibrations and the flat-plate calibrations are accredited by the National Voluntary Accreditation Program (NVLAP). This paper discusses the traceability involved in this radiometric calibration program. It also discusses numerous quality control measures that have been taken to improve and assure measurement accuracy for both calibrations.


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MS12_01_LIEBMAN
Picture of the productWattmeter Calibration for Use in Standby Power Testing to IE
Ilya Budovsky and Dimitrios Georgakopoulos
A growing number of household appliances include a standby mode, in which the appliance consumes a small amount of electrical power. Standard 62301 of the International Electrotechnical Commission (IEC) describes the measurement of standby power and the requirements for wideband wattmeters used for this purpose. These requirements include the ability to measure power with uncertainty of less than 0.01 W for current waveforms having crest factors up to 10. The National Measurement Institute, Australia, has developed a system for the calibration of wideband wattmeters used in the measurement of standby electrical power in accordance with IEC 62301. The system has uncertainties significantly lower than those required by the standard and has been tested with current waveforms having crest factors up to 20.


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MS12_01_BUDOVSK