Francesco Maria Grimaldi (April 2, 1618 - December 28, 1663) was an Italian mathematician and physicist who taught at the Jesuit college in Bologna.

Between 1640 and 1650, working with Riccioli, he investigated the free fall of objects, discovering that the distance of fall was proportional to the square of the time taken.

In astronomy, he built and used instruments to measure geological features on the Moon, and drew an accurate map or selenograph which was published by Riccioli.

He was the first to make accurate observations on the diffraction of light (although Leonardo da Vinci had earlier noted it), and coined the word 'diffraction'. Later physicists used his work as evidence that light was a wave, and Isaac Newton used it to arrive at his more comprehensive theory of light.

Publications

• Physicomathesis de lumine, coloribus, et iride, aliisque annexis (published 1665)