an optical lens, wherein the image beam emits to the optical lens and {HEAD ~ a part} of the image beam passes through {TAIL ~ the optical lens} to form a first projecting beam, and a part of the image beam is reflected by the optical lens to form a second projecting beam 
an optical lens , wherein the image beam emits to the optical lens and { HEAD ~ a part } of the image beam passes through { TAIL ~ the optical lens } to form a first projecting beam , and a part of the image beam is reflected by the optical lens to form a second projecting beam
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH