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