ratio of refraction
71Astigmatism — An optical system with astigmatism is one where rays that propagate in two perpendicular planes have different foci. If an optical system with astigmatism is used to form an image of a cross, the vertical and horizontal lines will be in sharp… …
72Jean de Beaugrand — Jean de Beaugrand, né entre 1584 et 1588[Note 1], mort à Paris le 22 décembre 1640, est un mathématicien français. Secrétaire royal, membre de l académie de Mersenne, ami et correspondant de Hobbes, de Fermat et de Galilée, il défendit… …
73Helium — otherusesHelium (He) is a colorless, odorless, tasteless, non toxic, inert monatomic chemical element that heads the noble gas group in the periodic table and whose atomic number is 2. Its boiling and melting points are the lowest among the… …
74Speed of light — The speed of light in the vacuum of free space is an important physical constant usually denoted by the letter c . [NIST and BIPM practice is to use c 0 for the speed of light in vacuum in accord with international standard ISO 31 5. See… …
75Prism (optics) — For other uses, see Prism (disambiguation). A plastic prism In optics, a prism is a transparent optical element with flat, polished surfaces that refract light. The exact angles between the surfaces depend on the application. The traditional… …
76index — 1. [NA] SYN: i. finger. 2. A guide, standard, indicator, symbol, or number denoting the relation in respect to size, capacity, or function, of one part or thing to another. SEE ALSO: quotient, r …
77Ray transfer matrix analysis — (also known as ABCD matrix analysis) is a type of ray tracing technique used in the design of some optical systems, particularly lasers. It involves the construction of a ray transfer matrix which describes the optical system; tracing of a light… …
78Near-surface geophysics — is the use of geophysical methods to investigate small scale features in the shallow (tens of meters) subsurface. It is closely related to applied geophysics or exploration geophysics. Methods used include seismic refraction and reflection,… …
79Polarization — ( Brit. polarisation) is a property of waves that describes the orientation of their oscillations. For transverse waves, it describes the orientation of the oscillations in the plane perpendicular to the wave s direction of travel. Longitudinal… …
80Black body — As the temperature decreases, the peak of the blackbody radiation curve moves to lower intensities and longer wavelengths. The blackbody radiation graph is also compared with the classical model of Rayleigh and Jeans …
