i need to find the thickness of optical fibre from interference pattern.

i have used an optical fibre as an object in holographic microscopy. i need to find the thickness of the optical fibre. i am new to the matlab platform. can anyone help me regarding the same .thanks in advance.

[Bjorn Gustavsson]

This first seems more like a physics-image-analysis than a matlab problem to me. For us to help you with this we would need far more information about your experiment - how are the image generated etc.

If you need to get going with matlab take a browse-through of the on-ramp material. That should get you a quicker (and from your choises more relevant for you) start on matlab-work.

[Walter Roberson]

Q: In the movie Star Wars, how large is the Imperial Battle Cruiser?

A: About 3 feet long. It just looks huge because of the camera angles and very very careful use of perspective.

Q: In your picture, how thick is the optical fibre?

A: 3 picometers, 3 billion light years, we have no way of knowing just by looking at it without additional information.

[Wan Ji]

YOUr humorous comment on this question make me happy after tiring work :) @Walter Roberson

[Image Analyst]

My guess is 3 billion light years. But @Febin Johny, you can use my attached spatial calibration demo to learn how to calibrate your images. Also, there is no clear sharp boundary for the white blob(s) in the image, so that diameter is a bit of a judgment call. Does the overall outer diameter correspond to the fiber diameter, or does the spacing between fringes represent the diameter?

Walter I notice you mix British and American English (fibre, meter) so do Canadians more usually follow British spellings or American spellings?

[Bjorn Gustavsson]

@Image Analyst, my naive guess is that the exit-end of the fibre acts as an apperture with regards to difraction - but there's clearly more optics/physics-setup involved to generate this image (not entirely dissimilar to the "concentric circles estimation"-question.)

[Walter Roberson]

@Image Analyst

We tend not to be careful about spelling at 3 AM ;-)

[Walter Roberson]

Is it the holograph that you have access to, and the task is to use MATLAB to reconstruct it, and then measure a feature of the resulting image?

https://en.wikipedia.org/wiki/Digital_holographic_microscopy

[Febin Johny]

@Image Analyst, i am doing an expirement related to holography microscopy. i just placed an optical fiber in one of the arm as an object reference. which you can see in the top as a horizontal line. so i want to whether its possible to find out the thickness of the optical fiber from the figure. i used an He-Ne laser and the distance between the object and ccd sensor is approximately 57cm.

[Image Analyst]

Why don't you simply chop off the tip of the fiber and image the fiber itself in a microscope?

[Walter Roberson]

https://www.spiedigitallibrary.org/ebooks/PM/analog-and-digital-holography-with-matlab/eISBN-9781628416596/10.1117/3.2190844?SSO=1

https://www.mathworks.com/academia/books/introduction-to-modern-digital-holography-with-matlab-poon.html

https://www.mathworks.com/matlabcentral/fileexchange/59939-holography-with-plane-waves-inline-in-line-gabor

[Bjorn Gustavsson]

...or check the data-sheet? Surely the characteristics of an optical fibre should be known in a lab-setting?

[Walter Roberson]

Though I guess sometimes it could be important to find the characteristics of the optical fibre as accurately as feasible, whereas the data sheet would have a range of sizes.

But I would wonder if it is a single-mode fibre or a multi-mode fibre ? The exact physical size of a multi-mode fibre can be less important than the "optical size" (the way the index changes determines the effective diameter...)

[Bjorn Gustavsson]

@Walter Roberson: Fair points, it also depends on whether the outer diameter of the fibre with cladding or only the core. If it is the core - I'd go with determining the effective diameter by the diffraction pattern light creates at the exit (however, since I've never managed to get a single photon into a fibre I don't know how to achieve this.). If it is the cladding maybe it is most efficient to use the fibre for a 2-slit type experiment.

[Walter Roberson]

I think it could be an interesting exercise to determine the effective core diameter based upon a hologram taken perpendicularly to a fibre that had been extracted from the outer poly shield.

But I would not expect the image to look anything like the posted image... could be wrong in my expectations.

[Image Analyst]

Maybe you could determine the diameter of the fiber (core and/or cladding) from the hologram, but if you have the actual fiber (and not just the hologram) I think the most direct route would be to simple take a picture of the fiber in a microscope with the right field of view and to measure it with the microscope manufacturer's software. You could probably see both the cladding and the core and get both of the diameters. Determining the diameter(s) from the image it makes seems like an indirect, and much more difficult and much less precise, method.

Answer 1

[yanqi liu]

sir，can you make some label to identify which part is the thickness