The screen is scanned by a laser spot having {HEAD ~ a diameter} which is {TAIL ~ less than 100 micrometer} 
is
The screen is scanned by a laser spot having { HEAD ~ a diameter } which is { TAIL ~ less than 100 micrometer }
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL