APPLICATION NOTE AN-708
VIBRATION MEASUREMENTS WITH THE VIBRATION SYNCHRONIZATION MODULE
INTRODUCTION
The vibration module allows complete analysis of cyclical events using low-speed cameras. This is accomplished by locking
on to a drive or response signal, and taking images at user-defined phase intervals.
Since the camera’s frame rate may not be fast enough to image several times during a single cycle, we may skip several
cycles before advancing to the next phase, but the signal is accurately tracked by the phase locking logic. For purely cyclical
motion, this results in a replication of a single wave cycle.
Because the timing device used by the vibration module is very accurate, the practical limitation on the oscillation
frequency is generally dependent on the camera sensitivity and the scene lighting, which both affect the system’s ability to
“freeze” the motion. The table below provides frequency range guidelines for several lighting options:
LIGHT SOURCE
Minimum Exposure Time Recommended Frequency Range Max Frequency
Room light 10ms 0 – 50Hz 100Hz
Halogen light
30µs
50 – 200Hz 500Hz
Stroboscope
1µs
100 – 4000 Hz 10kHz
Ultra bright stroboscope 40ns 2 – 10 kHz
50kHz
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