In {HEAD ~ one embodiment}, the positioner is {TAIL ~ a piezoelectric positioner} and in other embodiments, the positioner is a servomechanism or a shape memory alloy 
In { HEAD ~ one embodiment } , the positioner is { TAIL ~ a piezoelectric positioner } and in other embodiments , the positioner is a servomechanism or a shape memory alloy
OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH