The position of the tool holding unit is measured by an optical length measuring device, and {HEAD ~ the difference} between {TAIL ~ the measured value} and a desired value is compensated by the fine displacing drive unit 
between
The position of the tool holding unit is measured by an optical length measuring device , and { HEAD ~ the difference } between { TAIL ~ the measured value } and a desired value is compensated by the fine displacing drive unit
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH