Patent ID: 6084723
Filing Date: 2000-07-04
Classification: G02B,G03F

Abstract:
A projection optical system located between a first and second objects, for projecting an image of the first object onto the second object, said projection optical system comprising a first lens group with a positive refracting power, a second lens group with a negative refracting power, a third lens group with a positive refracting power, a fourth lens group with a negative refracting power, and a fifth lens group with a positive refracting power in order from the side of said first object,wherein when f.sub.1 is a focal length of said first lens group, f.sub.2 is a focal length of said second lens group, f.sub.3 is a focal length of said third lens group, f.sub.4 is a focal length of said fourth lens group, f.sub.5 is a focal length of said fifth lens group, f.sub.1-3 is a composite focal length of said first lens group to third lens group, f.sub.4-5 is a composite focal length of said fourth lens group and said fifth lens group, and L is a distance from said first object to said second object, the following conditions are satisfied:0.1<f.sub.1 /f.sub.3 <170.1<f.sub.5 /f.sub.4 <140.01<f.sub.5 /L<0.8f.sub.1-3 /f.sub.4-5 <2.5andwherein said first lens group comprises at least two positive lenses, said second lens group comprises at least two negative lenses, said third lens group comprises at least three positive lenses, said fourth lens group comprises at least three negative lenses, and said fifth lens group comprises at least five positive lenses and at least one negative lens.