a flow cell in which the object to be measured flows throughout {HEAD ~ a region} irradiated with {TAIL ~ the laser light} 
irradiated with
a flow cell in which the object to be measured flows throughout { HEAD ~ a region } irradiated with { TAIL ~ the laser light }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL