Projection optical system and method for photolithography and exposure apparatus and method using same

A lithographic projection apparatus arranged to project a pattern from a patterning device onto a substrate using a projection system and having a liquid supply system configured to at least partly fill a space between the projection system and the substrate with a liquid, wherein an element of the projection system through which the pattern is to be projected and configured to be at least in part in contact with the liquid, comprises first and second components of CaF2, or SiO2, the components being arranged such that the projected pattern passes through the first component before passing through the second component.

A device manufacturing method comprising projecting a patterned beam of radiation onto a substrate through a liquid provided in a space between an element of a projection system and the substrate,

• wherein a surface of the element in contact with the liquid comprises a member which is CaF2 or SiO2.

A device manufacturing method comprising projecting a patterned beam of radiation onto a substrate through a first liquid and a second liquid provided in a space between an element of a projection system and the substrate, wherein the first liquid is in contact with the element and the second liquid is in contact with the substrate.

A device manufacturing method comprising projecting a patterned beam of radiation onto a substrate through a liquid provided in a space between an element of a projection system and the substrate, wherein the element is at least in part in contact with the liquid and comprises first and second components of CaF2, or SiO2, the components being arranged such that the patterned beam of radiation passes through the first component before passing through the second component.