User:Daguilar/CSLDV

=Continuous Scan Laser Doppler Vibrometry= Continuous Scan Laser Doppler Vibrometry (CSLDV) is a method of using a Laser Doppler Vibrometer (LDV) in which the laser beam is swept across the surface of a test subject to capture the motion of a surface at many points simultaneously. This is different from scanning laser vibrometry (SLDV) in which the laser beam is kept at a fixed point during each measurement and quickly moved to a new position before acquiring the next measurement.

Advantages & Disadvantages
CSLDV can allow one to capture the mode shapes of a structure with high resolution much more quickly than would be possible with SLDV. Allen & Sracic show results where measurements were acquired with CSLDV in a hundredth of the time that would be required for LDV. Allen & Aguilar postulated that the additional detail available from CSLDV might provide important information when validating structural dynamic models. CSLDV also makes testing with an instrumented hammer practical with LDV, and some have speculated that CSLDV might be useful in cases where it is impossible to recreate the input forces, such as explosive loadings.

The primary disadvantage of CSLDV is the additional laser speckle noise that occurs if the laser spot scans the structure too quickly. Speckle noise is caused by micro-scale irregularities in the surface that change the intensity pattern of the laser light recieved by the LDV as it scans the surface. Similar problems are obtained when applying LDV to rotating shafts, for example. Speckle noise is difficult to predict, depending on the properties of the surface, the geometry of the structure and position of the LDV, so further research is needed to establish the limits of CSLDV.

History
Sriram et al seem to have been the first to publish regarding CSLDV, although they studied it for only a few years and discontinued research. Most of the subsequent advances in this area have arisen from the group at Imperial College in London by Stanbridge, Ewins, Martarelli and Di Maio  , who coined the term "CSLDV".

Links
The video in the link below illustrates the process and some of the scan patterns that are possible. Video of a CSLDV Test