Recording Interferometric Projections

When the method of axial tomography is employed, projection data of the field to be reconstructed has to be recorded from various angles. The experiments with the differentially heated fluid layer were conducted by turning the convection test cell with reference to the light source. The position of the light source and the detector remained fixed in all the experiments. The experiments were conducted at various angles and for each angle the full width of the fluid layer was scanned. The width of the fluid layer being 500X500 mm in plan, required several translations with the traversing mechanism to scan the complete fluid width for one projection angle. This is because the diameter of the laser beam was only 70mm. the data thus pecorded in the form of images were joined together using computer programs to generate one complete image corresponding to a given projection angle.

Figure 4.15: Combined Mach-Zehnder and Michelson interferometry for crystal growth from a solution