Three-window method

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Only the electrons passing through the selected energy slit contribute to these images.

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In the case of the three-window method

1) one window is positioned at the region of the edge onset of the element in question 2) The two other windows are positioned at energies below the edge onset.

Images acquired at these two windows are used to calculate the background image, this means, the background contribution to the image recorded at the edge onset. Subtraction of the former from the latter produces the elemental distribution map. The three-window method may be applied when the spectral region below the edge is not distorted by the presence of other elements thus allowing a good background fitting.