Kamal al-Din Hasan ibn Ali ibn Hasan al-Farisi;
or Abu Hasan Muhammad ibn Hasan (1267– 12 January 1319, long assumed to be 1320)) (Persian: كمالالدين فارسی) was a Persian Muslim scientist. He made two major contributions to science, one on optics, the other on number theory. Farisi was a pupil of the astronomer and mathematician Qutb al-Din al-Shirazi, who in turn was a pupil of Nasir al-Din Tusi.
According to Encyclopædia Iranica, Kamal al-Din was the most prominent Persian author on optics.