significant audio degradation, provided that it is played with a high quality cartridge and that the surfaces are clean. An alternative approach is to take a high-resolution photograph or scan of each side of the record and interpret the image of the grooves using computer software. An amateur attempt using a flatbed scanner lacked satisfactory fidelity. A professional system employed by the Library of Congress produces excellent quality. Stylus A development in stylus form came about by the attention to the CD-4 quadraphonic sound modulation process, which requires up to 50 kHz frequency response, with cartridges like Technics EPC-100CMK4 capable of playback on frequencies up to 100 kHz. This requires a stylus with a narrow side radius, such as 5 µm (or 0.2 mil). A narrow-profile elliptical stylus is able to read the higher frequencies (greater than 20 kHz), but at an increased wear, since the contact surface is narrower. For overcoming this problem, the Shibata stylus was invented around 1972 in Japan by Norio Shibata of JVC. The Shibata-designed stylus offers a greater contact surface with the groove, which in turn means less pressure over the vinyl surface and thus less wear. A positive side effect is that the greater contact surface also means the stylus will read sections of the vinyl that were not touched (or "worn") by the common spherical stylus. In a demonstration by JVC records "worn" after 500 plays at a relatively very high 4.5 gf tracking force with a spherical stylus, played "as new" with the Shibata profile. Other advanced stylus shapes appeared following the same goal of increasing contact surface, improving on the Shibata. Chronologically: "Hughes" Shibata variant (1975), "Ogura" (1978), Van den Hul (1982). Such a stylus may be marketed as "Hyperelliptical" (Shure), "Alliptic", "Fine Line" (Ortofon), "Line contact" (Audio Technica), "Polyhedron", "LAC", or "Stereohedron" (Stanton). A keel-shaped diamond stylus appeared as a byproduct of the invention of the CED Videodisc. This, together with laser-diamond-cutting technologies, made possible the "ridge" shaped stylus, such as the Namiki (1985) design, and Fritz Gyger (1989) design. This type of stylus is marketed as "MicroLine" (Audio technica), "Micro-Ridge" (Shure), or "Replicant" (Ortofon). Record materials To address the problem of steel needle wear upon records, which resulted in the cracking of the latter, RCA Victor devised unbreakable records in 1930, by mixing polyvinyl chloride with plasticisers, in a proprietary formula they called Victrolac, which was first used