Contd...

In an experiment, projection data can be recorded either by turning the crystal growth chamber or the source-detector combination. The latter is particularly difficult due to stringent requirement of alignment. With the first option, it is not possible to record a large number of projections, owing to the inconvenience of installing plane optical windows in a circular beaker. Further, for a cylindrical growth chamber, the entire field of interest cannot be imaged due to the curvature of the test cell. Instead, the central core region (corresponding to the size of the optical windows), that includes the growing crystal, has been recorded. In this respect, the projection data set is incomplete. In order to generate a complete projection data set for each view angle, an extrapolation procedure has been adopted and is discussed in the next section.

Projection data has been recorded for four view angles of in the present experiments. The data for 180⁰ is taken to be identical to that for zero angle. Information for intermediate view angles has been generated by employing linear interpolation on the experimentally recorded data.