An interface unit for positioning an object to be irradiated in relation to a radiation source has at least one first positioning surface for positioning the interface unit in relation to the radiation source, and a second positioning surface for bearing on the object to be irradiated. The interface unit provides a path, which passes through the second positioning surface, for the radiation from the radiation source. According to the invention, the interface unit comprises an integrally produced interface body which forms both the at least one first positioning surface and the second positioning surface. The interface body is preferably produced from a plastic material by an injection compression molding method, in order to achieve the desired high manufacturing accuracy.
