Étienne-Louis Malus was a French engineer and physicist born on September 23, 1775. He is best known for his work in the field of optics, particularly for discovering the phenomenon of polarization of light. His research laid the groundwork for understanding how light behaves when it interacts with different materials. Malus's most notable contribution is the invention of the Malus's Law, which describes how the intensity of polarized light changes as it passes through a polarizing filter. His findings have had significant implications in various fields, including photography, telecommunications, and even in the development of LCD screens. Malus passed away on July 23, 1812.