A lithographic apparatus includes a radiation source configured to produce a radiation beam, and a support configured to support a patterning device. The patterning device is configured to impart the radiation beam with a pattern to form a patterned radiation beam. A chamber is located between the radiation source and patterning device. The chamber contains at least one optical component configured to reflect the radiation beam, and is configured to permit radiation from the radiation source to pass therethrough. A membrane (44) is configured to permit the passage of the radiation beam, and to prevent the passage of contamination particles (54) through the membrane. A particle trapping structure (52) is configured to permit gas to flow along an indirect path from inside the chamber to outside the chamber. The indirect path is configured to substantially prevent the passage of contamination particles (58) from inside the chamber to outside the chamber.
