Patent ID: 7212289

Claim:
An interferometric measurement device for determining the birefringence in a transparent object having a useful aperture, comprising: an interferometer, which has an input for an input light beam, has an output at which an object light beam passing through the object interferometrically superposes with a reference light beam not passing through the object, a beam-shaping optical arrangement, through which at least the object light beam passes before entry into the object and which is designed in such a way that the object light beam has, when passing through the object, a beam cross section which corresponds to the useful aperture of the object; a positionally resolving measuring instrument for determining, at the interferometer output, a distribution of phase differences between the object light beam and the reference light beam over the beam cross section of the object light beam and the reference light beam; an instrument for modifying the polarization state of the input light beam; and, at least one further optical component, which produces, in a calibration state of the interferometric measurement device in which the object is removed, a calibration light beam which is guided in such a way that it does not pass through the entire beam-shaping optical arrangement, and which is interferometrically superposed with a light beam that does pass through the entire beam-shaping optical arrangement.