{HEAD ~ The shape} around {TAIL ~ the optical axis} of the scanning lens is concave, convex and concave from the first surface in the scan direction and concave, convex, concave and convex in the sub scan direction 
around
{ HEAD ~ The shape } around { TAIL ~ the optical axis } of the scanning lens is concave , convex and concave from the first surface in the scan direction and concave , convex , concave and convex in the sub scan direction
HEAD HEAD HEAD HEAD HEAD HEAD 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 OTH OTH OTH OTH OTH