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quenotl / PARESIS

Python ray-tracing and Fresnel code for speckle imaging simulation
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How can the software fully simulate a larger size item? #4

Open ddxy2021 opened 2 years ago

ddxy2021 commented 2 years ago

Hello, thank you very much, this program is very useful to me but I have a question, if I want to simulate a real sample, for example: the length is 250mm, how should I do it, when I set this length is much larger than the picture size. The size of the items simulated in the software is a few millimeters.How should I change the image magnification so that the software can fully simulate a larger size item?

ddxy2021 commented 2 years ago

One more question, can you recommend me some speckle tracking software that can be applied to the XST method? I'm very interested in this, thank you so much!

quenotl commented 2 years ago

Hello, To be honest I have never tried with samples that were that big. To increase the picture size you need to change the detector parameters in the Detector.xml. You can choose both the detector pixel size and the size of the array in pixels (dimX, dimY). The magnification is computed from the distances that are given in the Experiment.xml. The magnification of the sample is the total distance from the source to the detector (sum of the 3 given distances) divided by the distance from the source to the sample (sum of the first two distances).

For speckle tracking we also have a gitHub https://github.com/DoctorEmmetBrown/popcorn The part concerning speckle tracking is in the folder popcorn/phase_retrieval. The different methods that are used in this software are described and referenced in the pdf PhaseRetrieval_dataSheet in popcorn root folder. The way to use the soft is also described in that document. One point though: in our case the displacement of the speckles is usually smaller than a pixel and the algorithms might not work well with displacement of too big magnitude.

Thanks for your interest, have a nice day.

ddxy2021 commented 2 years ago

Thank you very much for your reply, your reply is very helpful to me, and the software is also great! There is another question I want to ask for advice, you said that the speckle displacement should be less than 1 pixel, so how should I do it in the experiment? For example, if I want to use the XSVT method to take 10 sets of pictures, and the detector pixel is 50 microns, what should be the displacement of my membrane each time? Thank you so much and have a nice day.

quenotl commented 2 years ago

I meant if the speckle displacement due to refraction when comparing sample and reference image is smaller than the pixel size (it is usually the case if you are not at extremely high resolution). For the experiment, the displacement of the membrane should be big enough so that one details of your sample is superimposed with a different modulation at each acquisition. Theoretically a displacement of a few modulations should be enough but it can be as big as you want. To be certain we usually use a displacement equivalent to 100 pixels.

ddxy2021 commented 2 years ago

Everything is clear, thank you very much!I will also try an XSVT step size of 100 pixels. Next week I will conduct an experiment on the XSVT method and I would also like to ask you what samples you usually choose in your experiments? I would like the transmission, dark field and phase diagrams to reflect the different characteristics of the samples. For example, a blueberry, or a Lego man, like in the literature? Do you have any suggestions for samples? The equipment in our lab is a microfocus x-ray source. Thank you again and have a great day and good work!

DoctorEmmetBrown commented 2 years ago

Hello. Sorry to be so late for answering. We have imaged a lot of different samples and the results strongly vary with acquisition parameters (source size/energy distance of propagation etc). We would be happy to help and share our résulta if you wish. Best. Emmanuel

ddxy2021 commented 2 years ago

Thank you for your reply, I would very much like to see the results of your images if possible, I have now completed an experiment trying to observe the gaps in the glass fiber sample but the phase diagram is very unclear. I am trying to change the parameters of the experiment and the software parameters in "Popcorn" and I think it would be very helpful if I could refer to your experiment.

Thank you very much and have a nice day!

ddxy2021 commented 2 years ago

Hello, if possible, I would like you to share me some completed speckle images, preferably with some experimental data (experimental distance, accelerating voltage, etc.), I would like to choose the right samples and experimental parameters according to your experiments and learn the software analysis process based on the speckle images you obtained. Thank you very much and have a nice day!

DoctorEmmetBrown commented 2 years ago

Hi. Sorry I didn’t see you replied. Yes of course it would be with pleasure to share. It would be more convenient to do it in zoom; don’t you think?

ddxy2021 commented 2 years ago

Thank you very much for your reply, I look forward to your sharing, can you share your Zoom account with me? Or my Zoom email is nikolafan1130@gmail.com. Thank you so much for your help!