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PTB-Certification for Interferometers highest accuracy over long distances Attocube’s interferometers have been tested by the National Metrology Institute of Germany (PTB). The accuracy of the interferometers has been confirmed at various pressure, humidity and temperature conditions over several days, thus also confirming the high performance and reliability of attocube’s ECU (environmental compensation unit). The IDS was checked over a working distance of 10 meters. The systematic error of measurement was quantified to 0.0 ppm between a working distance of 0 m and 3 m. The total expanded measurement uncertainty (k=2), consisting of the systematic and random measurement errors mostly remains under 0.4 ppm. 4 Expanded Measurement Uncertainty (k = 2) Average Systematic Error Line of 0.4 ppm 3 2 1 0 0 2500 5000 7500 10000 Working Distance(mm) The figure above shows the systematic measurement error and the measurement uncertainty of the IDS as certified by the PTB. They depend on the working distance. The blue line represents a measurement error of 0.4 ppm that surrounds the other lines, while the average systematic error is always lower than 0.19 ppm. Download the calibration certificate for the IDS/FPS at our website: IDS certificate FPS certificate