title: Digital microscopic holography for micrometer particles in air.
abstract: The development of a specific holographic setup designed for providing three-dimensional imaging of micrometer particles in a very small volume inside a large air-flow facility is described. Study of a 1.5 mm(3) volume is made possible with the use of a microscope objective for magnification of the object field. Particles that are too small to be detected with a standard in-line hologram (about 1 μm in diameter or less) are illuminated laterally, and the 90° scattered field is magnified and recombined with a reference wave for in-line recording. A calibration procedure relates reconstruction space coordinates to measurement volume coordinates. Analysis of the results shows that particle images reconstruct with very good axial accuracy. Preliminary tests show that this approach should allow measurements of fluid velocity very close to the wall in a wind-tunnel flow.
authors.affiliation: Mechanical Engineering Department, PUC-Rio, Rio de Janeiro 38097, Brazil. kuhlmann@puc‐rio.br
authors.forename: Juliana K
authors.initials: JK
authors.lastname: Abrantes
authors.forename: Michel
authors.initials: M
authors.lastname: Stanislas
authors.forename: Sébastien
authors.initials: S
authors.lastname: Coudert
authors.forename: Luis Fernando A
authors.initials: LF
authors.lastname: Azevedo