For a highly precise measurement of even low light intensities for the purpose of reduction of the analysis time, {HEAD ~ each light source} is switched on and off during {TAIL ~ a defined interval} by a clocked pulse sequence of constant pulse frequency alternately 
is switched off during
For a highly precise measurement of even low light intensities for the purpose of reduction of the analysis time , { HEAD ~ each light source } is switched on and off during { TAIL ~ a defined interval } by a clocked pulse sequence of constant pulse frequency alternately
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH