The diffuser plate 4 has {HEAD ~ the function} of emitting {TAIL ~ light source light} diffusingly in a predetermined angular range 
The diffuser plate 4 has { HEAD ~ the function } of emitting { TAIL ~ light source light } diffusingly in a predetermined angular range
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH