{HEAD ~ The line source image} is maintained in focus during scanning by synchronous refocussing of {TAIL ~ the imaging system} 
{ HEAD ~ The line source image } is maintained in focus during scanning by synchronous refocussing of { TAIL ~ the imaging system }
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL