Expansion 

This article needs some major expansion on numerous fronts.  Techniques that should be added or expanded:
stereoscopic piv
dual-plane stereoscopic piv
micropiv
scanning piv
holographic piv

Equipment should be expanded on to include some mention of the optics and lasers utilized.  Software and analysis techniques should also be mentioned to complete the entry.  I do have experience in the field but haven't done large edits before.  So if you see a formatting error please point it out.