Fraunhofer Institute for Physical Measurement Techniques IPM
Fraunhofer flagship project QMag (completed)
In the Fraunhofer flagship project QMag, Fraunhofer IPM has researched the industrial suitability of optically pumped magnetometers (OPM), including magnetic field measurements into our sensor technology portfolio. OPM exhibit extreme measurement accuracy, which is directly connected to atomic constants (see Fig. 1).
Due to their sensitivity, OPM can serve as detectors for nuclear magnetic resonance (NMR). Standard NMR normally uses very strong magnetic fields. We transfer the methods known from the high-field range to the range of lowest magnetic fields (zero-to-ultra-low-field, ZULF) with B < 1 µT up to the range of the earth’s field (EF) with B < 100 µT. Using the resulting low frequencies we improve the compatibility of NMR signals with metallic components. The aim is to build NMR-based flow meters that measure multiphase flows.
At the same time, we make OPM usable for materials testing. For this purpose, we integrate OPM into micro-fatigue setups in order to measure the time course of stray magnetic fields in metal samples. These stray fields are generated by cracks and flaws in the material and can help to detect and measure the smallest cracks in the material even before crack initiation occurs. The presently known magnetic field strengths of these stray fields are in the range of nT - µT, which can be measured very easily with OPM.
