optique

Optics is the branch of physics that studies light, its generation, propagation, and interaction with matter, and its detection by the human eye or instruments. It covers how light travels through space, how it is reflected and refracted, and how it can be diffracted, scattered, or absorbed. Historically it has been divided into geometrical optics, which treats light as rays and is useful for lenses and mirrors, and wave optics, which treats light as a wave and explains interference, diffraction, and polarization.

Key concepts include reflection at interfaces, refraction according to Snell's law, interference, and diffraction patterns. Lenses and mirrors manipulate light to form images in devices such as cameras and telescopes. Maxwell's equations describe light as electromagnetic radiation and underpin much of the theory of optics. In modern terms, the field also includes quantum optics, which studies light at the level of photons, and nonlinear and fiber optics, which enable high-speed communications and advanced photonic technologies.

Historically, optics traces to ancient civilizations and was advanced by figures such as Euclid, Ibn al-Haytham, and later Newton and Huygens. The 19th century established the wave–particle duality, and the 20th century brought lasers, fiber optics, and quantum optical ideas. Today optics underpins imaging, vision science, astronomy, telecommunications, medical instrumentation, and consumer electronics, spanning instruments like endoscopes, cameras, spectrometers, and optical fiber networks.