Reconstruction of an object using Fringe Images

Hi everyone, I am pretty new to the community so I hope this question would be okay. (This is a photonics-based inquiry; Regarding Interferometry)

I have designed a code that allows me to stack fringe images (resulting in a 3-D array) that were collected in a real interferometer setup and using Matlab I was able to plot the maximum intensity values from these surface data results.

The object that was used in the interferometer setup was a step-like object. And my main inquiry is how would i reconstruct this object from the surface data that I have collected?

If the information provided was not sufficient please let me know :)

Answer 1

[Pratyush]

Hi Kavin,

To reconstruct a step-like object from interferometric data, follow these summarized steps:

• Use Fourier transform methods or phase-shifting algorithms to extract phase information from the fringe patterns.
• Apply phase unwrapping techniques, like quality-guided or path-following methods, to resolve phase values beyond the ([-π, π]) range.
• Convert phase information to actual height measurements by calibrating the system with known standards or through systematic calibration based on the optical setup and light wavelength.
• Convert the unwrapped, calibrated phase map into a height profile of the object, potentially using surface fitting to smooth out noise and errors.
• Use software like MATLAB to visualize the reconstructed surface and analyze the height profiles for validation.

Note:

• Reduce noise in your images before processing.
• Choose robust algorithms for phase unwrapping and reconstruction, especially for complex shapes.
• Validate your reconstructed profiles with known dimensions or alternative measurement techniques for accuracy.

This approach will help you reconstruct the height profile of a step-like object from your collected interferometric surface data.