Observed (data points) and model (curves) polarization fraction measured along the top disk surface from the edge of the coronagraphic mask to the outer edge of the disk. The red and black model curves only differ by the maximum grain size, with a_max = 3000 and 50 µm, respectively. The inset presents the same image as in Fig. 4, and the solid blue and green lines correspond to the radius along which the polarization rate is measured. The limits between the average pixel values are represented by the two dashed gray lines.