Abstract: An optical arrangement, in particular a plasma light source (1?) or an EUV lithography apparatus, with a housing (2), which encloses an interior housing space (3), a vacuum generating unit for generating a vacuum in the housing (2), at least one surface (13), which is disposed in the interior housing space (3), a cleaning device (15) which removes contaminating substances (14) deposited on the surface (13), and also a monitoring device (25) which monitors the surface (13), the monitoring device (25) having monitoring optics (26) that can be directed onto the surface (13). The cleaning device (15) is configured to remove the deposited contaminating substances (14) by the discharge of CO2 in the form of CO2 pellets (17).