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