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