An optical film (140, 540, 640, 740,840, 940, 1040, 1140, 1240, 1340, 1440, 1540, 1640, 1740) having opposed first and second structured surfaces, the optical film (140, 540, 640, 740,840, 940, 1040, 1140, 1240, 1340, 1440, 1540, 1640, 1740) comprising: a plurality of extended prisms (141, 541, 641, 741, 841, 941, 1041, 1141, 1241, 1341, 1441, 1541, 1641, 1741) formed on the first structured surface; and a plurality of extended split spreading structures (142, 542, 642, 742, 842, 942, 1042, 1142, 1242, 1324, 1424, 1524, 1642, 1742) formed on the second structured surface, the split spreading structures (142, 542, 642, 742, 842, 942, 1042, 1142, 1242, 1342, 1424, 1524, 1642, 1742) extending along an elongation axis (144, 1549-2, 1649-2, 1749-2, 1849-2, 1949-2), each split spreading structure (542, 642, 742, 842, 942, 1042, 1142, 1242, 1324, 1424, 1524, 1642, 1742) having a high spreading portion (542a, 642a, 742a, 842a, 942a, 1042a, 1142a, 1242a, 1324a, 1424a, 1524a, 1642a, 1742a) with a high light spreading characteristic disposed alongside a low spreading portion (542b, 642b, 742b, 842b, 942b, 1042b, 1142b, 1242b, 1324b, 1424b, 1524b, 1642b, 1742b) with a low light spreading characteristic; wherein the prisms and the split spreading structures (141,142, 541, 542, 641, 642, 741, 742, 841, 842, 941, 942, 1041, 1042, 1141, 1142, 1241, 1242, 1341, 1342, 1441, 1442, 1541, 1542, 1641, 1642) are arranged in a one-to-one correspondence of prisms (141, 541, 641, 741, 841, 941, 1041, 1141, 1241, 1341, 1441, 1541, 1641, 1741) to split spreading structures (142, 542, 642, 742, 842, 942, 1042, 1142, 1242, 1324, 1424, 1524, 1642, 1742), characterized in that the low spreading portion (542b, 642b, 742b, 842b, 942b, 1042b, 1142b, 1242b, 1324b, 1424b, 1524b, 1642b, 1742b) and the high spreading portion (542a, 642a, 742a, 842a, 942a, 1042a, 1142a, 1242a, 1324a, 1424a, 1524a, 1642a, 1742a) meet along a boundary that is parallel to the elongation axis of the split spreading structure in plan view. a plurality of extended prisms (141, 541, 641, 741, 841, 941, 1041, 1141, 1241, 1341, 1441, 1541, 1641, 1741) formed on the first structured surface; and a plurality of extended split spreading structures (142, 542, 642, 742, 842, 942, 1042, 1142, 1242, 1324, 1424, 1524, 1642, 1742) formed on the second structured surface, the split spreading structures (142, 542, 642, 742, 842, 942, 1042, 1142, 1242, 1342, 1424, 1524, 1642, 1742) extending along an elongation axis (144, 1549-2, 1649-2, 1749-2, 1849-2, 1949-2), each split spreading structure (542, 642, 742, 842, 942, 1042, 1142, 1242, 1324, 1424, 1524, 1642, 1742) having a high spreading portion (542a, 642a, 742a, 842a, 942a, 1042a, 1142a, 1242a, 1324a, 1424a, 1524a, 1642a, 1742a) with a high light spreading characteristic disposed alongside a low spreading portion (542b, 642b, 742b, 842b, 942b, 1042b, 1142b, 1242b, 1324b, 1424b, 1524b, 1642b, 1742b) with a low light spreading characteristic; wherein the prisms and the split spreading structures (141,142, 541, 542, 641, 642, 741, 742, 841, 842, 941, 942, 1041, 1042, 1141, 1142, 1241, 1242, 1341, 1342, 1441, 1442, 1541, 1542, 1641, 1642) are arranged in a one-to-one correspondence of prisms (141, 541, 641, 741, 841, 941, 1041, 1141, 1241, 1341, 1441, 1541, 1641, 1741) to split spreading structures (142, 542, 642, 742, 842, 942, 1042, 1142, 1242, 1324, 1424, 1524, 1642, 1742), characterized in that the low spreading portion (542b, 642b, 742b, 842b, 942b, 1042b, 1142b, 1242b, 1324b, 1424b, 1524b, 1642b, 1742b) and the high spreading portion (542a, 642a, 742a, 842a, 942a, 1042a, 1142a, 1242a, 1324a, 1424a, 1524a, 1642a, 1742a) meet along a boundary that is parallel to the elongation axis of the split spreading structure in plan view.