Determination of the size and location of a discontinuity in a waveguide by inversion of measured scattered wavefields

It is shown that the combined use of: 1) a rigorous, numerically efficient, model of the measurements, on a strip of the upper face of the waveguide, of the response to mono mode monochromatic probe radiation, and 2) an itera tive non-linear least-squares scheme to minimize the discrepancy between me asured and theoretical response, enables a fairly-accurate retrieval, in ne ar real-time, of the two location and one size parameters of the discontinu ity. (C) 2000 Academie des sciences/Editions scientifiques et medicales Els evier SAS.