Effect of different wavelengths on the polarization model of the VLTI light path. The top panel is similar to Fig. 7, showing the measured polarization angle (corrected for field rotation) for all four telescopes and all linear input states in gray. The model is shown in four wavelengths (1900, 2000, 2250, and 2500 nm). As the model repeats after 180°, only the range from 0 to 180 degrees is shown. The bottom panel shows a scaled-up view of the model for state 4 without the data.