Patent ID: 8208125

Claim:
A projection optical system used for an exposure apparatus that uses an i-line as a light source, and configured to project a pattern of an original that is placed on an object plane onto a substrate that is placed on an image plane, the projection optical system comprising a plurality of lenses made of a plurality of types of different glass materials which include a lens having an Abbe number equal to or smaller than 62, wherein the plurality of lenses include, in order from the object plane along an optical path, a first lens unit having a positive power, a second lens unit having a negative power, a third lens unit having a positive power, a fourth lens unit having a negative power, and a fifth lens unit having a positive power, wherein the projection optical system satisfies following equations, where NAO is a numerical aperture of the projection optical system on the object plane, β is an imaging magnification of the projection optical system, Td is a distance on an optical axis from the object plane to the image plane, Dt is a sum of thicknesses of the glass materials on the optical axis in the projection optical system, OB 1 max is a maximum object height on the object plane, and OB 2 max is a maximum image height on the image plane: 0.125≦NAO −0.251<β<−0.249 80 mm≦| OB 1max| 20 mm≦| OB 2max| | Dt /( NAO·|OB 1max|)|≦62.0 Dt/Td≦ 0.645 0.072≦| OB 1max|/ Td 1.