The optical device 11, wherein {TAIL ~ the surface area} of {HEAD ~ the used part} is no more than one third of the total surface area of the spatial light modulating element 
The optical device 11 , wherein { TAIL ~ the surface area } of { HEAD ~ the used part } is no more than one third of the total surface area of the spatial light modulating element
OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH