| 摘要 |
<p>This invention relates to optical systems used in semiconductor manufacturing, and more particularly to an catadioptric optical reduction system comprising, from the long conjugate end to the short conjugate end, a first lens group of positive power; a second lens group of negative power; a beamsplitter; a quarter waveplate; a concave mirror; a third lens group of positive power; wherein the positive power of said first lens group provides enough power to image an entrance pupil at infinity through said second lens group to an aperture stop at or near said mirror, the negative power of said second lens group provides the necessary conjugates for said concave mirror, and the positive power of said third lens group provides the remainder of the total system power and images the exit pupil to infinity. Preferred embodiments provide acceptable imaging over a spectral full-width-half-maximum bandwidth of 300 picometers, such that a narrowed excimer laser can be employed for the illumination source. <IMAGE></p> |
