The Status of PTB's Nanonewton Force Facility

The nanonewton force facility of PTB (Physikalisch-Technische Bundesanstalt, Germany), first presented in [1]-[3], has been significantly improved. In this work, we will demonstrate that the facility is able to measure forces in the range below 1 μN with a resolution below 5 pN and an uncertainty below 2.7 % for a measured force of 1 nN at a measuring duration of about 20 s. We will demonstrate the use of the facility as a calibration device. We will also present measurements methods and the results for the spring constant of a cantilever, the contact potential difference and the negative light pressure.