A light source 14 wherein {HEAD ~ said helical portion} turns through {TAIL ~ an angle} of at least about 720° 
turns through
A light source 14 wherein { HEAD ~ said helical portion } turns through { TAIL ~ an angle } of at least about 720 °
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH