EXTRAPOLATION SCHEME

The experimental set up employed in the present work enables only a part of the aqueous solution in the beaker to be scanned by the laser beam, being limited by the size of the optical windows. The projection data is thus incomplete, as shown schematically in Figure 5.17. Specifically, the experimental data in the form of the schlieren images covers about 25% of the beaker diameter.

Figure 5.17: Definition of partial projection data.

In order to successfully apply the CBP algorithm for tomographic inversion, one needs projection data over the entire width of the physical domain for each view angle. In the present work, the experimentally recorded partial data has been extrapolated to derive information about the portion of the solution beyond the optical windows. In all experiments, the region inclusive of the crystal has been imaged; extrapolation is applied to the portion of the field from the edges of the laser beam to the walls of the beaker.