projecting {HEAD ~ a patterned beam} of radiation onto {TAIL ~ a substrate} held on the substrate table 
projecting { HEAD ~ a patterned beam } of radiation onto { TAIL ~ a substrate } held on the substrate table
OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH