RECONSTRUCTIONS 1/3

 

Introduction

We present here some numerical and experimental results of 2D object reconstruction in microwave tomography . We illuminate an object with an electromagnetic incident field, and from the scattered field, we can reconstruct 2D cross-section of the object.

Numerical results

Numerical setup

The domain D is a square of 3L x 3L (L is the wavelengh corresponding to a frequency of 2.45GHz). D is discritized under 29 x 29 square cells, and the distance between the receivers and the center of the object is 9L. The scattered field is measured on 29 receivers and for 29 different illuminations. More informations can be found in the paper [2].

Reconstruction of profile P3 ( cf. Thesis )

The object is made by 2 concentric square cylinders. The outer cylinder has a side of 2L and a complex permittivity of 1.3 + 0.4i, while the inner cylinder has a side of L and a complex permittivity of 1.6 + 0.2i. This object is also used in [van den Berg and Kleinman, Inverse Problems, 11, 1995]. We compute different reconstructions of this profile, using a Conjugate Gradient algorithm and different regularization scheme.

You can see the results (with images and animated GIF).

Experimental results

Experimental setup

Results presented in this section are provided courtesy by the Rome Laboratory, Electromagnetics & Reliability Directorate, 31 Grenier Street, Hanscom AFB, MA 01731-3010. More informations can be found in the paper [Coté, IM-41(2):185-192, 1992].

Reconstruction of a polystyrene square cylinder

The value of the real part of the complex permittivity of the polystyrene object is 1.03 while the imaginary part is null. The object has a size of 11.2 cm and the frequency used is 10 GHz. The domain is discretized into 29x29 square cells of size 5.3 mm. We have a data set including 6 illumination angles for 351 measures.

Here are the results.