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kipochem
Germany
1 Posts |
 Posted - 12/13/2013 : 05:46:29 AM
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Origin Ver. and Service Release (Select Help-->About Origin): 9.1 Pro
Operating System: Win 7
Hello!
I just started to use Origin, so please excuse my newbie-questions :)
I am doing measurements of the contact angle of droplets of a certain liquid deposited on a certain surface.
Normally I have a programme which calculates the angle automatically, but because of the nature of the liquid and the avaible luminosity the programme os not able to calculate it correctly.
Consequently I have to calculate the contact angle "manualy"
Is it possiblie firstly to interpolate a circle around the liquid/air-interface by setting the interpolating points on this interface and then calculating the tangent through the intersection of the interpolated circle and the baseline of the droplet?(the baseline is always set)
Once the tangent and the baseline are set, is it finally possible to calculate the angle between these two lines?
You can find a before/after picture (made with paint) of what I mean in the attachment.
Thanks a lot!
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Hideo Fujii
USA
1582 Posts |
Posted - 12/13/2013 : 11:18:46 AM
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Hi kipochem,
Here is just my suggestion, and there should be better ways.
Please see the attached screenshot according to the steps below:
1) Take a screenshot of the essential part of your image, and import to Origin. ("sample.jpg" matrix window)
2) Detect edges ("Image: Spacial Filters: Edge" menu with appropriate method and parameters, Gradient north west,
and Threshold=11 in my sample). (MBook1)
3) Convert the matrix to XYZ data, and extract edge data by filtering out black areas. (Book1)
4) Plot the data, and mask unnecessary data points. (Graph1)
5) Fit the plot with appropriate function (in my sample, implicit fitting with an ellipse) (Graph2)
6) Perform Analysis:Mathematics: Differentiate to get tangent.
Convert tangent to angle (then to degree, if you prefer). (Book2)
Hope this suggestion helps a bit.
--Hideo Fujii
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contact angle measurement