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Production sequence of Si-spheres and interferometrical determination of the sphere volume

Interferometry on Gauge Blocks

Working Group 5.43

Profile

Dissemination of the SI unit of the meter via calibration of gauge blocks, and of prismatic material measures resembling gauge blocks, with very small measurement uncertainties; this task is stipulated by Section 6 of the Units and Time Act [Einheiten- und Zeitgesetz, 2008]. Measurement of thermal expansion.

 

Developing and operating special imaging interferometers to realize the length of material measures with the highest possible accuracy. Measurements of absolute length as a function of temperature and time elapsed make it possible to investigate the thermal expansion and long-term stability of materials with a high degree of accuracy.

Assessment of gauge-block calibration laboratories accredited by DAkkS.

Provision of consulting services for calibration laboratories and training measures on the handling and calibration of gauge blocks.

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Research/Development

Research/Development

The primary focus of our work in research and development is on the further development of imaging interferometry; here, our goal is to be able to measure the length of prismatic material measures with increasing precision in order to meet demand. The knowledge gained in this way is beneficial for the services offered by the working group within the scope of special measurements, and forms the foundation for ongoing improvements to its interferometers. Furthermore, recently developed interferometers such as the Ultra-Precision Interferometer are available for testing material properties such as thermal expansion between 7 K and 50 °C and long-term response of the sample's length; these measuring devices are the only ones of their kind in the world. Here, our aspiration is to gain ever-greater control over the sub-nanometer range in order to meet the demands of industry for decreasing tolerances.

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Services

Dissemination of the SI unit of the meter via calibration of gauge blocks as specified in DIN EN ISO 3650, and of prismatic material measures resembling gauge blocks, with very small measurement uncertainties, as a task stipulated by Section 6 of the Units and Time Act [Einheiten- und Zeitgesetz, 2008]. Measurement of the thermal expansion of gauge blocks. Metrological consulting services for special measurements.

Assessments of gauge-block calibration laboratories accredited by DAkkS.

Provision of consulting services for calibration laboratories and training measures for calibration employees on handling and calibrating gauge blocks. Provision of metrological support to PTB’s Technical Cooperation department for development aid projects.


Gauge BlocksGauge Blocks

Gauge blocks in accordance with DIN EN ISO 3650

 

 

Gauge blocks are the most precise and most widely used embodied standards of length for the dissemination of the unit of length—the meter—to industry and research. This is due to the fact that they have a simple geometric form, provide highly accurate measurements, are reliable and can be calibrated with very small measurement uncertainties. The German standard DIN EN ISO 3650 (1999) specifies the most important dimensional and metrological characteristics of gauge blocks that have a rectangular cross section and a nominal size ln in the range from 0.5 mm to 1000 mm.

 

 

 

 

 

The most precise length measurements of parallel and prismatic material for traceability of the unit of lenght - the meter -, are realized by optical interferometry. Gauge blocks calibrated by the PTB with the smallest measurement uncertainties are considered the most precise reference standards (in the hierarcy of traceability to national standards) by DAkkS certified calibration laboratories.

The types of calibration, measurement uncertainties and prices can be found in the list of fixed charges for gauge block calibrations.

 

 


Traceability


Measuring devices


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Information

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