The time-averaging Doppler global velocimeter obtains three distinct velocity components by illuminating observation plane from three different directions in succession. Although this arrangement requires three separate light sheet generators a single receiving camera is necessary to obtain three-component data.
A uniform intensity distribution across each light sheet is achieved through the use of scanning optics - in this case, a rotating slab of glass which exhibits a nearly linear beam translation with respect to its rotation. The small translation is then magnified through a set of cylindrical lenses.
The existing light sheet generators provide parallel sheets with a width of up to 130 mm, although divergent sheets can also be created. The typical beam oscillation frequency lies in the 10-50 Hz range.