Optics
Optics (appearance or look in ancient Greek) is a branch of Physics that describes the behavior and properties of Light and the interaction of Light with Matter. Optics explains and is illuminated by optical phenomena. The field of optics usually describes the behavior of Visible, Infrared and Ultraviolet light; however because Light is an electromagnetic wave, analogous phenomena occur in X-rays, microwaves, Radio waves, and other forms of Electromagnetic radiation. Optics can thus be regarded as a sub-field of Electromagnetism. Some optical phenomena depend on the Quantum nature of light and as such some areas of optics are also related to Quantum mechanics. In practice, the vast majority of optical phenomenon can be accounted for using the electromagnetic description of light, as described by Maxwell's equations. Optics, however, as a field is often considered largely separate from the physics community. It has its own identity, societies, and conferences. The pure science aspects of the field are often called Optical Science or Optical Physics. Applied optical sciences are often called optical engineering. Applications of optical enginering related specifically to illumination systems is called illumination engineering. Each of these disciplines tends to be quite different in its applications, technical skills, focus, and professional affiliations. Because of the wide application of the science of "light" to real-world applications, the area of optical science, and optical engineering tends to be very cross-disiplinary. Optical science is a part of many related disciplines including electrical engineering, physics, psychology, medicine, and others. Additionally, the most complete description of optical behavior, as known to physics, is unnecessarily complicated for most scenarios so particular simplified theories are used. These limited theories adequately describe subsets of optical phenomenon while ignoring behavior irrelevant and/or undetectable to the system of interest. Branches of opticsOptics has two primary branches: Physical optics and geometrical optics.Classical opticsBefore Max Planck suggested that light is quantized, optics consisted mainly of the application of electromagnetism and its high frequency approximations to light.Geometric optics, sometimes called ray optics is the branch of optics that describes Light Propagation in terms of rays. Rays are bent at the Interface between two dissimilar media, and may be curved in a Medium in which the Refractive index is a function of position. The Ray in geometric optics is perpendicular to the wavefront in wave optics. Note that such a description is a significant simplification of optics, and fails to account for many important optical effects such as diffraction and polarization. (This same approximation is generally called Classical mechanics when applied to matter, but the term optics is also used to describe charged particle motion in magnetic and electrical fields.) An even more simplified version of ray optics is Gaussian optics, wherein all rays are assumed to be paraxial. In which case the mathematical behavior simplifies to be purely linear, and allows optical components and systems to be described by simple matrices. Less extreme approximations include Physical optics. Topics related to classical optics
Modern opticsModern Optics is a term used to describe areas of optical science and engineering that became popular in the 20th century. These areas of optical science typically relate to the electromagnetic or quantum properties of light but do include other topics.Topics related to modern optics
Other optical fields
Everyday opticsOptics is part of everyday life. Rainbows and appearances of fata morgana or the Green flash are examples of optical phenomena. Many people benefit from eyeglasses or contact lenses, and optics are used in many consumer goods including cameras.Wikibooks modules
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