Catadioptric lens and optical system comprising such a lens

A catadioptric lens having an optical axis, the catadioptric lens comprising:

• a first mirror comprising a first substrate and a first reflective coating on a first boundary layer of the first substrate, the first reflective coating extending from the first boundary layer along a first surface normal;
• and
• a second mirror comprising a second substrate and a second reflective coating on a second boundary layer of the second substrate, the second reflective coating extending from the second boundary layer along a second surface normal,
• wherein:
• the first and second mirrors are arranged along the optical axis;
• the first reflective coating comprises one or more first plies;
• an optical overall layer thickness of the one or more first plies increases along a radial direction extending outwardly from the optical axis;
• the
• the catadioptric lens is configured so that, for a used wavelength range of light of the catadioptric lens, after the light reflects from a reflective coating of an optical element of the catadioptric lens, the catadioptric lens reduces by a factor of at least two a phase retardation between radially and tangentially polarized light by:
• i) reflection of the light at at least one coating selected from the group consisting of the first reflective coating and the second reflective coating;
• or
• ii) transmission of the light through an anti-reflection coating of a mirror selected from the group consisting the first mirror and the second mirror;
• the used wavelength range of light has a minimum wavelength of light and a maximum wavelength of light;
• and
• the maximum wavelength of light is at least 1.1 times the minimum wavelength of light.