08-11-2017, 03:25 PM
Optics is the branch of physics that involves the behavior and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics generally describes the behavior of visible, ultraviolet and infrared light. Because light is an electromagnetic wave other forms of electromagnetic radiation such as X-rays, microwaves, and radio waves, exhibit similar properties.
Most optical phenomena can be explained using the classical electromagnetic description of light. The complete electromagnetic descriptions of light are, however, often difficult to apply in practice. Practical optics are generally done using simplified models. The most common of these, geometric optics, treats light as a collection of rays that travel in straight lines and curve when they cross or reflect on surfaces. Physical optics is a more complete light model, which includes wave effects such as diffraction and interference that can not be taken into account in geometric optics. Historically, the ray-based light model was developed first, followed by the light wave model. Progress in electromagnetic theory in the nineteenth century led to the discovery that light waves were actually electromagnetic radiation.
Some phenomena depend on the fact that light has properties similar to waves and similar to particles. The explanation of these effects requires quantum mechanics. When considering properties similar to particles of light, light is modeled as a collection of particles called "photons". Quantum optics deals with the application of quantum mechanics to optical systems.
Optical science is relevant and studied in many related disciplines, including astronomy, various fields of engineering, photography and medicine (particularly ophthalmology and optometry). The practical applications of optics are found in a variety of technologies and everyday objects, including mirrors, lenses, telescopes, microscopes, lasers and fiber optics.