optics, scientific study of light light, visible electromagnetic radiation . Of the entire electromagnetic spectrum , the human eye is sensitive to only a tiny part, the part that is called light. The wavelengths of visible light range from about 350 or 400 nm to about 750 or 800 nm.
..... Click the link for more information. . Physical optics is concerned with the genesis, nature, and properties of light; physiological optics with the part light plays in vision vision, physiological sense of sight by which the form, color, size, movements, and distance of objects are perceived.

Vision in Humans

The human eye functions somewhat like a camera; that is, it receives and focuses light upon a photosensitive
..... Click the link for more information. ; and geometrical optics with the reflection reflection, return of a wave from a surface that it strikes into the medium through which it has traveled. The general principles governing the reflection of light and sound are similar, for both normally travel in straight lines and both are wave phenomena.
..... Click the link for more information. and refraction refraction, in physics, deflection of a wave on passing obliquely from one transparent medium into a second medium in which its speed is different, as the passage of a light ray from air into glass.
..... Click the link for more information. of light as encountered in the study of the mirror mirror, in optics, a reflecting surface that forms an image of an object when light rays coming from that object fall upon it (see reflection ). Usually mirrors are made of plate glass, one side of which is coated with metal or some special preparation to serve as a
..... Click the link for more information. and the lens lens, device for forming an image of an object by the refraction of light. In its simplest form it is a disk of transparent substance, commonly glass, with its two surfaces curved or with one surface plane and the other curved.
..... Click the link for more information. .

optics

Science concerned with the production and propagation of light, the changes it undergoes and produces, and closely related phenomena. Physical optics deals with the nature and properties of light; geometric optics deals with the formation of images by mirrors, lenses, and other devices that use light. Optical data processing involves manipulation of the information content of an image formed by coherent (one-wavelength) optical systems. The study of optics has led to the development of devices such as eyeglasses and contact lenses, telescopes, microscopes, cameras, binoculars, lasers, and optical fibres (see fibre optics).

Optics

Narrowly, the science of light and vision; broadly, the study of the phenomena associated with the generation, transmission, and detection of electromagnetic radiation in the spectral range extending from the long-wave edge of the x-ray region to the short-wave edge of the radio region. This range, often called the optical region or the optical spectrum, extends in wavelength from about 1 nanometer to about 1 millimeter. See Geometrical optics, Physical optics

The discoveries of the experimentalists of the early seventeenth century formed the basis of the science of optics. The statement of the law of refraction, the development of the astronomical telescope, observations of diffraction, and the principles of the propagation of light all came in this relatively short period. The publication of Isaac Newton's Opticks in 1704, with its comprehensive and original studies of refraction, dispersion, interference, diffraction, and polarization, established the science.

In the early 19th century many productive investigators established the transverse-wave nature of light. The relationship between optical and magnetic phenomena led to the crowning achievement of classical optics—the electromagnetic theory of J. C. Maxwell. Maxwell's theory, which holds that light consists of electric and magnetic fields propagated together through space as transverse waves, provided a general basis for the treatment of optical phenomena. In particular, it served as the basis for understanding the interaction of light with matter and, hence, as the basis for treatment of the phenomena of physical optics. See Electromagnetic radiation, Light, Maxwell's equations

In the twentieth century optics has been in the forefront of the revolution in physical thinking caused by the theory of relativity and especially by the quantum theory.

The science of optics finds itself in a position that is satisfactory for practical purposes but less so from a theoretical standpoint. The theory of Maxwell is sufficiently valid for treating the interaction of high-intensity radiation with systems considerably larger than those of atomic dimensions. The modern quantum theory is adequate for an understanding of the spectra of atoms and molecules and for the interpretation of phenomena involving low-intensity radiation, provided one does not insist on a very detailed description of the process of emission or absorption of radiation. However, a general theory of relativistic quantum electrodynamics valid for all conditions and systems has not been worked out.

The development of the laser has been an outstanding event in the history of optics. The theory of electromagnetic radiation from its beginnings was able to comprehend and treat the properties of coherent radiation, but the controlled generation of coherent monochromatic radiation of high power was not achieved in the optical region until the work of C. H. Townes and A. L. Schawlow in 1958 pointed the way. Many achievements in optics, such as holography and interferometry over long paths, have resulted from the laser. See Holography, Interferometry, Laser

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Vision in Humans

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Optics
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