Multifocus tomographic algorithm for measuring optically thick specimens.

Area of Science:

• Optical Physics
• Image Reconstruction
• Materials Science

Background:

• Accurate characterization of refractive index is crucial for optical materials.
• Existing tomographic methods face challenges with optically thick phase objects.
• Transverse dimensions often exceed imaging system depth-of-field.

Purpose of the Study:

• To introduce a novel tomographic algorithm for 2D refractive index reconstruction.
• To validate the algorithm using interference microscopy of optical fibers.
• To demonstrate broad applicability in optical metrology and imaging.

Main Methods:

• Developed a tomographic algorithm utilizing 1D projections.
• Acquired projections at multiple focal positions and angular orientations.
• Applied the algorithm to reconstruct refractive index fluctuations in optical fibers.

Main Results:

• Successfully reconstructed 2D refractive index fluctuations.
• Validated the method with measurements of multicore and microstructured optical fibers.
• Demonstrated the algorithm's effectiveness for optically thick phase objects.

Conclusions:

• The novel tomographic algorithm provides accurate 2D refractive index reconstruction.
• The method is suitable for optically thick specimens where transverse dimensions are large.
• This technique offers significant benefits for optical fiber metrology and other imaging applications.