I need to study the surface of nylon-6 blank fibres with a thickness of nearly 40 micrometre. I work in optics lab with many optical components such as beam splitters, lenses, mirrors, etc; can I build a system to study the topology of this fibre?


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  • $\begingroup$ Not exactly an answer, but I did a research project in undergrad that studied the surface morphology of thin films using a Scanning Electron Microscope and, separately, an Atomic Force Microscope. Neither were built in-house, however. $\endgroup$ – Kyle Kanos Mar 20 at 11:48

Here are some suggestions:

  1. Study the surfaces using a microscope, to get a direct sense of the 3D structure of your samples. This can work if the features you are analyzing are larger than about 1/2 the wavelength of the illuminating light. A confocal microscope can give you better resolution. Adjusting the focal plane up and down can help determine where features are in the vertical direction.

  2. Using the same samples, illuminate the samples with a narrow collimated laser beam. Using a high-quality lens, focus the scattered light to form the optical Fourier transform of the scattered light. The light pattern should correspond to the sizes and arrangements of the fibers/features in the samples. Use a polarized laser beam and view the scattered light pattern through a polarizing filter to get additional information. Different laser wavelengths may give you somewhat different results, providing yet more information.

  3. Consider using a process called "ptychography". It is related to #2 above, but can be used to obtain extremely detailed images without lenses. Variations on the technique can be used to obtain 3D images of microstructures.

  • $\begingroup$ Thank you @S. McGrew Is there any schematic diagrams, papers, references ... etc to understand the whole thing better? and about the ptychography method, is there any free to access code to reconstruct the data? $\endgroup$ – Muhamed Sewidan Mar 20 at 15:57
  • $\begingroup$ I have not searched for ptychography code. However, you could try searching GitHub, alternatively, you could contact authors of some selected papers on ptychography. $\endgroup$ – S. McGrew Mar 20 at 16:35
  • $\begingroup$ but this method can investigate the surface of polymer fibre? as this fibre has branches on the main backbone, will the tomography be able to characterise these features? $\endgroup$ – Muhamed Sewidan Mar 20 at 16:40
  • $\begingroup$ If the features are smaller than about 1/3 micron, you will probably need to use another method, like electron microscopy. There might be a correlation between the diffraction pattern in suggestion #2 and the branching angles in your polymer sample, but you will need to have some method to more specifically determine the features, before you can meaningfully interpret the diffraction pattern. Are you hoping to image the molecules themselves? That can't really be done optically. $\endgroup$ – S. McGrew Mar 20 at 18:24
  • $\begingroup$ No, I don't need to image the molecules, I have studies the thickness of two fibres with laser diffraction, and it is showed that the fibre with branches has a higher thickness, therefore I need a method to investigate this grafting process and its impact to the blank fibre surface. $\endgroup$ – Muhamed Sewidan Mar 21 at 8:44

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