Analyses of squealing disk brakes generally show main frequencies from 1 to 10 kHz. On a test stand holograms exposed by time average and double-pulse techniques are recorded from various types of disk brakes. Photographs of reconstructions from those holograms display a vibration pattern in a simple topographical map of fringes, which represents contours of equal vibration amplitudes on the brake components: That would be i.e. yoke-type or fist-type callipers, brake pads and brake disk.
Holographic Vibration Analysis is a useful method for looking at these small vibration amplitudes to understand different mechanisms of coupling. Also it is possible to localize vibration sources in squealing disk brakes.