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A round robin comparison of freeform form measurements was carried out by the project partners and stakeholders of a European metrology research project. Altogether six measuring instruments were considered: five different (pointwise and areal) optical devices and one tactile device. Three optical freeform surfaces were used for the comparison measurements, where two specimens were measured by...

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The paper presents the effect of mechanical mounting of optical reference elements on their surface shape. Optical reference surfaces are key elements when traceable, highly accurate and precise optical surface measurements are required. In order to calibrate measuring instruments and compare the metrological capabilities of different metrology institutes, universities and other stakeholders, the...

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Quasi als Nebenprodukt bei den Arbeiten zum „neuen“ Kelvin haben Wissenschaftler der Physikalisch-Technischen Bundesanstalt (PTB) eine völlig neuartige Methode zur Druckmessung realisiert, die primär ist, also nur von Naturkonstanten abhängt. Als eine unabhängige Methode kann sie zur Überprüfung der genauesten Druckmessgeräte dienen, bei denen die PTB ...

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Im Zuge der Revision des SI Einheitensystems, die am 20. Mai 2019 in Kraft trat, hat das beratende Komitee für die „Länge“ (CCL) der internationalen Meterkonvention vorgeschlagen, den Gitterparameter des Siliziumkristalls als Basis für die sekundäre Darstellung des Meters im Nanometerbereich zu nutzen. In der hochauflösenden Mikroskopie sind damit Pikometerunsicherheiten für Messungen von...

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Ein DKD-Ringvergleich zur Bestimmung von Rauheitskenngrößen an Raunormalen und Tiefeneinstellnormalen sowie der verwendeten Auswertesoftware zwischen DAkkS akkreditierten Laboratorien und der PTB wurde erfolgreich durchgeführt. Alle akkreditierten Laboratorien konnten ihre Kompetenz im akkreditierten und teilweise auch im nichtakkreditierten Servicebereich nachweisen.

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Die Herstellung additiv gefertigter Werkstücke erweitert signifikant die Möglichkeiten des Wissenschaftlichen Gerätebaus, Kundenanforderungen an Design und Funktionsumfang um-zusetzen. Das Laser-Pulverbettverfahren mit den Grundwerk-stoffen Polyamid, Edelstahl, Aluminiumlegierung und Titanlegierung erlaubt u.a. die Integration von innenliegenden Strukturen wie Kühlkanälen, strömungsbeeinflussenden...

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With the increasing use of atomic force microscopes for the mechanical characterization of nanomaterials, the need to determine the contact area of the cantilever tip increases. A novel stylus tip testing standard, developed at PTB with rectangular grooves and edge radii in the nm range, has now been used for the first time to determine the tip shape of an AFM tip. The measurements prove that the...

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FEM simulations were used to identify the most important influencing parameters on the non-linearity of capacitive displacement sensors. Geometric parameters, the surface roughness and the local distribution of surface potentials can also influence the non-linearity of the displacement measurement. For the validation of the simulations, capacitive sensors with different properties were...

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The metrological large range atomic force microscopy (Met. LR-AFM) has been further extended for reference metrology for quantitative areal surface measuring 3D-microscopy. The application includes the traceable and accurate calibrations of ISO 25178 series of standards, as well as the development of a novel circular chirp sample. The research progress characterized by a reduced noise level of...

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Since implementing a high-accuracy coordinate measuring machine extensive investigations were carried out to estimate the achievable measurement uncertainty. In cooperation with the manufacturer of the machine measurements were realised at one- and two-dimensional geometrical standards like parallel gauge blocks and step gauges as well as sphere and hole plates. These investigations contribute to...

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The virtual coordinate measuring machine is a powerful software tool to determine the task-specific measurement uncertainty using Monte-Carlo simulations. Following a substantial update and extension of the physical models and their thorough verification, the first DAkkS-accredited calibration laboratories were reviewed. In preparation of the audits, the assessors were trained by the PTB and...

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For dimensional quality assessment with computed tomography both fast measurements and adequately low measurement deviations are required. In cooperation with the manufacturer of CT machines YXLON GmbH a new measurement method was developed, where less X-ray projections are required compared to an average CT scan, and the evaluation is done without tomographic reconstruction. With this procedure...

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Medicine is placing high expectations on implants and auxiliary materials that are manufactured specifically for each individual patient. This can be done by means of additive manufacturing methods (3D printing), which allows nearly any complex shape to be produced. Before starting to use such implants widely, the medical sector and certification bodies demand proof of the fact that their high...

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An "Absolute Multiline System" was integrated into the Large Coordinate Measuring Machine (large CMM) in the "WIND" Competence Centre (CCW) within the framework of a project funded by the BMWi. The commercial system allows the precise absolute length measurement of distances over several meters by means of a laser beam coupled in via optical fiber and a reflector. The laser source with multiple...

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The operation of a refractometer cell in a pressure range beyond the usual atmospheric pressure fluctuations is necessary if, for example, the compressibility of a material measure is to be investigated. Due to the associated pressure-induced optical path length changes, a correction has been derived in order to take this effect into account in the result. For interferometric length measurements...

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The EMPIR research project 18SIB01 ‘Large-scale dimensional measurements for geodesy - GeoMetre’ was launched on June 1, 2019. In this, novel refractivity-compensating length measurement technologies will be applied to surveying problems in satellite geodesy. One of the targets is to improve the traceability of the International Terrestrial Reference Frame (ITRF) to the SI definition of the metre....

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The book released under this name from the publisher IOPScience arose with a major contribution from PTB authors. Based on the representation of a length according to the definition of the meter in the International System of Units and its realization, this comprehensive book covers the basic concepts of length metrology, sophisticated methods to reach smallest measurement uncertainties in length...

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Light sources are typically assumed to be monochromatic when these are used for length measurements by interferometry. From the calibrated frequency of the light source, the (vacuum-) wavelength can be calculated on a relative level of 10−12. To our surprise, while implementing a new I2-stabilized Nd:YAG laser, a relative error in the order of up to 10−7 was observed in length measurements by...

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