Publications Details

Widefield laser Doppler vibrometer using high-speed cameras

Reu, Phillip L.; Hansche, Bruce D.

Laser Doppler vibrometers (LDVs) have become the standard for out-of-plane velocity measurement because they are non-contacting, have wide signal bandwidth and high resolution, and are relatively easy to use. A typical drawback of LDVs is their limitation to single point measurements. This limitation is mitigated by scanning technology, but at the cost of the time required to sample all the points on a surface and the inability to measure transient, non-repetitive events. A more proficient alternative is a Widefield LDV (WLDV), which heterodynes the Doppler frequency down from the typical MHz range (depending on velocity) to the kHz range. In WLDV, the modulated signal is detected via a high-speed CMOS camera and the optimum modulation signal is calculated from a measured velocity on the target obtained with a traditional single point LDV. This paper will present preliminary lab results of a full-field velocity animation obtained using a WLDV system to measure the velocity of a block on a turntable. A comparison highlighting the similarities and differences of similar systems, such as Temporal Speckle Pattern Interferometry and traditional LDV is discussed.