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