Rheintacho's tried and tested hand-held units record rotational speeds and run lengths. Some of them use a proximity system by shining a light beam on a reflective mark; others use a contact system with special adapters for different applications.
The new hand-held stroboscope measures rotation and vibrations even in the most inaccessible places. No physical intervention is required on the systems to be tested. If the stroboscope flash frequency matches the frequency of movement, the test object appears stationary.