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