{HEAD ~ The optical element} includes lenses, fθ lenses, {TAIL ~ prisms}, parallel flat plates and fly eye integrators 
includes
{ HEAD ~ The optical element } includes lenses , fθ lenses , { TAIL ~ prisms } , parallel flat plates and fly eye integrators
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH