{HEAD ~ The height} of the convex parts and {TAIL ~ the pitch} between adjoining concave and convex parts are selected so that projections produced by adjoining secondary light source images are displaced from each other by a half phase 
{ HEAD ~ The height } of the convex parts and { TAIL ~ the pitch } between adjoining concave and convex parts are selected so that projections produced by adjoining secondary light source images are displaced from each other by a half phase
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH 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 OTH