Scientists have developed a high‑resolution magnetic line camera to measure magnetic fields in real time. Field lines in magnetic systems such as generators or motors that are invisible to the human eye can be made visible using this camera. It is especially suitable for industrial applications in quality assurance during the manufacture of magnets.

The line camera visualizes magnetic field values in real time. (© Max Etzold)

The line camera can measure magnetic fields in real time and thus quickly detect defective magnets. It has become possible for the first time to integrate this kind of magnetic testing into industrial processes. The heart of the device is a 3D Hall‑effect sensor that enables a sensor chip to detect in all three axes any magnetic field present. These kinds of sensors can solve a range of measurement problems, such as rotation angle sensors, separation and positional sensors, and rpm sensors.

Using the camera, it is possible to measure the strength and direction of the magnetic field at 32 positions spaced 2.5 mm apart. The field lines thus become visible along the line over a distance of 8 cm, and can be monitored and recorded. The measuring procedure takes just a millisecond, so the camera provides 1,000 images per second. This speed allows the magnetic camera to be built into production facilities and test magnets on a running conveyor belt.