Method for approximating an influence of an optical system on the state of polarization of optical radiation

Method for approximating an influence of an optical system on the state of polarization of optical radiation comprising the steps of:

• providing incoming optical radiation for said optical system in several incoming states of polarization including at least one incoming state having predominantly circularly polarized radiation components,
• directing said incoming optical radiation onto said optical system,
• measuring at least one characteristic of a resulting outgoing optical radiation emerging from said optical system with respect to each of said incoming states of polarization including measuring a phase distribution and an intensity distribution of the outgoing optical radiation with respect to each of the incoming states of radiation by means of an interferometer,
• wherein the phase distribution and the intensity distribution are respective distributions over at least portions of the exit pupil of the optical system,
• and approximating the influence of said optical system on the state of polarization of optical radiation by calculating at least one of the rotation and the circular dichroism of said optical system from said measured characteristics of said outgoing optical radiation.