A projection lens (10) for a microlithographic projection exposure apparatus has a first optical element, for example a birefringent lens (L2), that has polarization dependent properties causing intensity fluctuations in an image plane of the projection lens. These fluctuation may be produced by a second optical element (24), for example a polarization selective beam splitting layer (28), that is arranged downstream of the first optical element. A gray filter (32; 132; 232) disposed in the beam path reduces the intensity fluctuations.
An optical system for a projector and an imaging method thereof. A light beam from a light source passes through a first lens set and a second lens set sequentially. The light beam having passed through the second lens set is reflected by a first mirror to pass through the second lens set again and arrived at an imaging device. The light is reflected from the imaging device to a projection lens set to project the light beam onto a screen.
