| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a projection optical system that has achieved reduction in manufacturing costs and size although both-side telecentric is achieved as well as a sufficient exposure area and a large numerical aperture, while restricting an increase in the number of composing lenses. <P>SOLUTION: A projection optical system for projecting an image of a first object onto a second object comprises, in order from the first object side toward the second object: a first lens group having positive refractive power; a second lens group having negative refractive power and having a pair of negative lenses forming a pair of concave faces facing each other; a third lens group having positive refractive power; an aperture stop; a fourth lens group having positive refractive power; a fifth lens group having negative refractive power and having a pair of negative lenses forming a pair of concave faces facing each other; and a sixth lens group having positive refractive power. The projection optical system satisfies the following conditions: 0.3<f1/fa<1.3, -0.36<f2/fa<-0.08, and 0.13<f3/fa<0.5. <P>COPYRIGHT: (C)2013,JPO&INPIT |
