Reading the tomography graphs¶

To first approximation, if the object tomography application try to track is perfect in xy but off in z ( off eucentric), the movement of the z-projected object during tilting follows a sine curve. On the other hand, if the object is perfect in z but offset on the xy plane in direction perpendicular to the tilt axis, the movement of the projected object follows a cosine curve, as show here:

Therefore, the curve below on x-axis which is almost perpendicular to the tilt axis suggests the specimen is 10 um off in z and the tilt axis passes quite close to the center of the CCD.