Measurement of three-dimensional temperature fields above heated surfaces by holographic interferometry

Abstract

Optical holography can be used to record multi-directional interferometric data, which provides a basis for measuring three-dimensional, asymmetric temperature or density fields in fluids. If continuous optical pathlength data are available over a 180° angle of view, the temperature or density field is shown to be equal to the inverse Radon transform of the data. A procedure for computing limited-resolution reconstructions of the field in terms of discrete data collected over a limited angle of view is presented. The technique of holographic interferometry was used to map isothermal contours in the developing convective plume above heated, horizontal, rectangular surfaces. It was found that the thermal structure of the developing plume is strongly influenced by the partitioning of the flow adjacent to the surface along lines of geometric symmetry.