Abstract
A method of labeling the first and second exposure particle images of a double-exposed particle image velocimetry (PIV) recording using a single-wavelength, double-pulsed laser is demonstrated. This was achieved by rotating the polarization plane of the second pulse of the illuminating laser beam using a Pockels cell in conjunction with a polarization-sensitive adaptive optic placed close to the iris plane of the photographic camera objective. This system effectively changed the transfer characteristics of the recording optics between exposures, producing two sets of particle images modulated by orthogonally oriented fringes. The particle images that correspond to each exposure were then separated by digital spatial filtering. This permitted the individual particle fields to be cross correlated to yield unambiguous displacement vectors. The technique can be applied to any flow in which the seeding particles retain the incident polarization plane in side scatter. The advantages and disadvantages of such a system compared with conventional PIV recording are discussed.
© 1995 Optical Society of America
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