An optical arrangement, in particular a projection exposure apparatus (1) for EUV lithography, includes: a housing (2) that encloses an interior space (15); at least one, in particular reflective, optical element (4 to 10, 12, 14.1 to 14.6) that is arranged in the housing (2); at least one vacuum generating unit (3) for generating a vacuum in the interior space (15) of the housing (2); and at least one vacuum housing (18, 18.1 to 18.10) that is arranged in the interior space (15) of the housing (2) and that encloses at least the optical surface (17, 17.1, 17.2) of the optical element (4 to 10, 12, 14.1 to 14.5), wherein a contamination reduction unit is associated with the vacuum housing (18.1 to 18.10), which contamination reduction unit reduces the partial pressure of contaminating substances, in particular of water and/or hydrocarbons, at least in close proximity to the optical surface (17, 17.1, 17.2) in relation to the partial pressure of the contaminating substances in the interior space (15).