Optik

Optik, or optics, is the branch of physics that studies light: its production, propagation, interaction with matter, and detection. It treats light as both a wave and a particle, and it analyzes how light is transformed by lenses, mirrors, fibers, and other media, as well as how it is perceived by human vision and by sensors.

Historically, optics developed from geometric descriptions of light rays used by ancient and medieval scholars to modern electromagnetic theory. Ibn al-Haytham (Alhazen) made early experiments on vision and light propagation. In the 17th and 18th centuries, geometrical optics and wave theories advanced with Newton, Huygens, and later Fresnel and Young. In the 19th century, James Clerk Maxwell unified light with electromagnetism, and the 20th century saw the rise of quantum optics, treating light as photons and exploring its quantum properties.

Subfields include geometrical optics (ray tracing, lenses, refractive systems), physical optics (interference, diffraction, polarization), quantum optics (photons, quantum states), nonlinear optics (frequency conversion), and applied areas such as fiber optics, holography, and photonics.

Core concepts include reflection, refraction, Snell's law, Fermat's principle, dispersion, interference, diffraction, and polarization. Optical materials have varying refractive indices, and dispersion causes different wavelengths to travel at different speeds.

Applications span imaging (cameras, microscopes, telescopes), medical and scientific instrumentation (endoscopy, spectroscopy, optical coherence tomography), communication (fiber-optic networks), and laser technology. Ongoing research explores metasurfaces, nanophotonics, and quantum information processing.