Phonograph record a "De luxe" price. Later, Decca Records introduced vinyl Deccalite 78s, while other record companies used vinyl formulations trademarked as Metrolite, Merco Plastic, and Sav-o-flex, but these were mainly used to produce "unbreakable" children's records and special thin vinyl DJ pressings for shipment to radio stations. In the 1890s, the recording formats of the earliest (toy) discs were mainly 12.5 cm (nominally 5 inches) in diameter; by the mid-1890s, the discs were usually 7 inches (nominally 17.5 cm) in diameter. By 1910, the 10-inch (25.4 cm) record was by far the most popular standard, holding about of music or other
Beam diameter Beam diameter The beam diameter or beam width of an electromagnetic beam is the diameter along any specified line that is perpendicular to the beam axis and intersects it. Since beams typically do not have sharp edges, the diameter can be defined in many different ways. Five definitions of the beam width are in common use: D4σ, 10/90 or 20/80 knife-edge, 1/e, FWHM, and D86. The beam width can be measured in units of length at a particular plane perpendicular to the beam axis, but it can also refer to the angular width, which is the angle subtended by the