The measurement of the intensity of the emission light during these intervals is exclusively performed during the switch on {HEAD ~ phases} of {TAIL ~ the light}, source  
of
The measurement of the intensity of the emission light during these intervals is exclusively performed during the switch on { HEAD ~ phases } of { TAIL ~ the light } , source
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH