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