So, for example, if I have a sodium ion over here, and I have a chloride ion over here, where the distance from center to center r I'm denoting as r, this is nucleus to nucleus separation.

The center distance of two holes is equal to the center distance of the corresponding venting hole and the water hole of the boiler.

Consequently, the measuring accuracy will no longer be restrained by the center-to-center distance of the picture elements.