Abstract: A device for the optical measurement of an optical system, in particular an optical imaging system, is provided. The device includes at least one test optics component arranged on an object side or an image side of the optical system. An immersion fluid is adjacent to at least one of the test optics components. A container for use in this device, a microlithography projection exposure machine equipped with this device, and a method which can be carried out with the aid of this device are also provided. The device and method provide for optical measurement of microlithography projection objectives with high numerical apertures by using wavefront detection with shearing or point diffraction interferometry, or a Moiré measuring technique.