Yes, you're right. So effectively the black spot is going to be of a sufficient size to create a shaded area over 95% of the area that the pupil is likely to b

Yes, you're right. So effectively the black spot is going to be of a sufficient size to create a shaded area over 95% of the area that the pupil is likely to be at any one time. That's going to be difficult without having internally looking cameras that monitor the pupil.