Wavelength coding laser tomography for flow visualizations

Laser-based volumetric colour-coded three-dimensional particle velocimetry

“…For example, sequenced colour illumination combined with colour imaging has been used in PIV to resolve directional ambiguity [13], phases in twophase flows [14], and for unambiguously colour coding long particle tracks, useful in measuring recycling and turbulent flows [15]. For increasing spatial information in particle velocimetry, two overlapping lightsheets of different colours have been used to obtain 3/2D-3C PIV [16][17][18]. However, as with a similar scheme based on a single monochromatic lightsheet with graded irradiance [6], extraction of the third spatial dimension with these schemes is very sensitive to absolute image intensity, which is practically difficult to control when imaging scattering particles.…”

Recent evolutions of imagery in fluid mechanics: From standard tomographic visualization to 3D volumic velocimetry

“…So, this method can give strictly simultaneous information on N different sections, qualitative (single visualization) or quantitative (e.g. N close velocity fields), even for unsteady flows [10]; of course, it presents the same disadvantage as stereo recording since a set of cameras is necessary. But, it also presents a lot of advantages: the gap between each section can be adjusted easily and the investigated volume increased easily too.…”

Laser-based volumetric flow visualization by digital color imaging of a spectrally coded volume

“…For example, liquid crystal tracers have been used to determine flow temperature 7 and quantum dot emitters have been used to increase the number of trackable particles in tomographic methods. [13][14][15] In order to record information over a substantial depth ͑3C-3D͒, two thick sheets of differing wavelength can be overlapped to form a color gradient in the depth direction. The use of a sequence of multiwavelength illumination pulses has allowed particles in complex recycling and turbulent flows to be tracked unambiguously.…”