As seem in the attached foto, the scale bar of a TEM image usually consists of a horizontal line of length L, end-capped with small vertical bars (of a finite thickness d)
When one tries to calibrate/measure the Scale bar of a TEM images, there seems to be three options (see the attached foto). Depending on which of the THREE options is used, the measured parameters (interplanar distances or particle size, for example) may have slightly different values depending on the thickness (d) of the vertical endbars of the scale bar.
Haven't seen scale bars like yours for a while. It looks like today manufacturers use just plane bar with no vertical bars. Following analogy with plane bar, I would measure from outer edges. However it does not matter if your TEM is not calibrated, spacial error should be expected to be greater than error induced by chosen method of measurement. If TEM was in-lab calibrated, then you should ask your question a person who calibrated it.
My understanding is that you measure between the midlines or from the inner edge to the outer edge.
Haven't seen scale bars like yours for a while. It looks like today manufacturers use just plane bar with no vertical bars. Following analogy with plane bar, I would measure from outer edges. However it does not matter if your TEM is not calibrated, spacial error should be expected to be greater than error induced by chosen method of measurement. If TEM was in-lab calibrated, then you should ask your question a person who calibrated it.
Dear Sajjad
I would choose B Figure, from the outer edges, without
having the vertical bars. Try to make it simple by having
only the horizontal bar from the outer edges.
Thank you for the answers. I will try to contact the technician to get a better idea of how they calibrated the TEM.
Like Vladimir already pointed out, most of the TEMs nowadays will use some sort of digital recording device to capture the signals. Scale bars are then recalculated from the known pixel size (more detailed information can be found here: http://www.globalsino.com/EM/page3243.html), so it is a good idea to use the original data (images), which still posses information on magnification and correction factor from calibration. Depends on you camera, but one of such softwares is Digital Micrograph from Gatan, which is capable of opening the .dm3 & .dm4 files from Gatan cameras, and can be downloaded from their webpage.
Therefore, if you are interested in such small differences, I suggest using un-altered data, to minimise the possible errors.
Of course if you use older devices, it is possible that you are still dealing with the negatives. Also then you'll have to digitalize them, eventually. This page has some useful information on that process:
https://www.einstein.yu.edu/research/shared-facilities/analytical-imaging-facility/aif.aspx?id=33836
I would answer that figure B is the correct scale for measuring. (I would assume that the electron microscope is properly calibrated unless you have reason to doubt it's accuracy.)
As others pointed, use digital ruler (in ImageJ you will easily find that).
Otherwise, use the outer edge on the left and the inner edge on the right - this is a better way for type C measurement
Dear Sajjad Ullah Sir,
I think (B) is the best measurement because you are measuring a length of the particle, if you want to calculate the width of the fringe then you have to measure like (C).
Usually there are no vertical bars in the TEM images, just a horizontal bar and you have it measure it from beginning till end.
As I know, no need to use vertical bars, just the horizontal bar is enough and measure from the outer edges.
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