Optical tomography of transparent objects with phase-shifting interferometry and stepwise-shifted Ronchi ruling

Area of Science:

• Optical physics
• Tomography
• Interferometry

Background:

• Phase objects are crucial in various scientific fields.
• Accurate phase measurement is essential for material characterization.
• Existing tomographic methods can be complex and computationally intensive.

Purpose of the Study:

• To develop an efficient experimental setup for tomographic inspection of phase objects.
• To encode phase information as digital image rows for sinogram construction.
• To enable tomographic reconstruction of phase slices using standard procedures.

Main Methods:

• Utilizing a common-path interferometer with two input windows and a translating grating.
• Encoding phase distribution of projections as digital image rows.
• Generating composite interferograms and performing phase stepping via grating translation.

Main Results:

• Successfully encoded phase distribution of projections into composite interferograms.
• Demonstrated phase stepping to obtain unwrapped phase distribution as a sinogram.
• Achieved tomographic reconstruction of phase slices for transparent samples.

Conclusions:

• The presented system offers a viable method for tomographic phase object inspection.
• The common-path interferometer design simplifies the experimental setup.
• The method allows for standard tomographic reconstruction of phase slices.