| 摘要 |
<P>PROBLEM TO BE SOLVED: To reduce value F while suppressing an occurrence of aberration and enlarging of device size, in a projection lens. <P>SOLUTION: An optical system which is telecentric to the reduction side is composed by arranging: a negative first lens L1 with a concave surface faced to the reduction side; a positive second lens L2 with a convex surface faced to the enlargement side; a negative third lens L3 with a concave surface faced to the enlargement side; a positive fourth lens L4 with the convex surface faced to the reduction side; a positive fifth lens L5; and a positive sixth lens L6 in this order from the enlargement side. In this case, when the air converted back focus of the whole lens system is Bf and focal distance for the whole lens system is f, a conditional expression (A):1.2≤Bf/f≤2.5 is satisfied. <P>COPYRIGHT: (C)2012,JPO&INPIT |
