“…Here, we will demonstrate that a similar constrained inversion procedure can be developed using the Kirchhoff approximation [2-4) for a flat elliptical crack. Using the results of our previous paper [5), an explicit coordinate-invariant expression that relates the time difference, ~t, between the arrival of the waves diffracted from the flashpoints of the crack and the crack shape and orientation is obtained. This expression, together with ~t measurements in different scattering directions is placed into a regression analysis to obtain a set of equivalent flat elliptical crack parameters.…”