a sensor for detecting a at least one of a secondary electron and reflected electron emanated from the object, upon {HEAD ~ exposure} of {TAIL ~ the object} to the electron beam 
of
a sensor for detecting a at least one of a secondary electron and reflected electron emanated from the object , upon { HEAD ~ exposure } of { TAIL ~ the object } to the electron beam
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH