The shape around {HEAD ~ the optical axis} of {TAIL ~ 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 
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The shape around { HEAD ~ the optical axis } of { TAIL ~ 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
OTH OTH OTH HEAD 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