Valdivia N., Williams E.

Near-field acoustical holography (NAH) requires the measurement of the near-field pressure field over a conformal and closed surface in order to recover the acoustic field on a nearby surface. Very often we encounter applications where pressure measurements are available only over a small open surface. In these cases the strict NAH theory does not hold, but still there are techniques used to overcome this difficulty. The best known is patch NAH, which has been used for planar surfaces. In this work we will discuss two techniques used for general surfaces: patch inverse boundary element methods (IBEM) and patch NAH using equivalent sources. We will discuss the theoretical justification of the approximations used in these methods, the effect in the edges of the reconstructions produced by the partial surface measurements data and finally the use of Cauchy data to overcome the edges effect in the reconstructions. We use a curved panel excited by a shaker as an example to validate our results. This work was supported by ONR.