Coating processes – Optical element produced – Polarizer – windshield – optical fiber – projection screen – or...
Patent
1995-02-16
1997-03-25
Beck, Shrive
Coating processes
Optical element produced
Polarizer, windshield, optical fiber, projection screen, or...
427231, 427233, 427237, 4272555, 4272556, 427429, 264 124, 264 127, C03C 1732, B05D 506
Patent
active
056142536
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a preform for plastic optical fiber, a process and an apparatus for producing a plastic optical fiber, and a process for the drawing of a plastic optical fiber.
BACKGROUND ART
A plastic optical fiber comprising a core and a cladding both of which comprise a plastic is rather suitable for an optical transmission line to be used for a short distance such that the transmission loss in the line disposed between devices for sending and receiving an optical signal poses substantially no problem (for example, that between electronic devices), as compared with a glass optical fiber. In addition, since a plastic optical fiber can generally be produced at a lower cost than that of a glass optical fiber, such a fiber is widely used as an optical transmission line for a short distance. Thus, the importance of a plastic optical fiber has been increased, particularly in view of a project or design for a next-generation communication network such as LAN (local area network) and ISDN (integrated service digital network).
Heretofore, there has been put into practical use a plastic optical fiber 1, as shown in a schematic perspective view of FIG. 23, which comprises a core 2 comprising a resin such as PMMA (polymethyl methacrylate resin), PC (polycarbonate resin), or a copolymer thereof; and a cladding 3 comprising a fluorine-containing resin, etc., and has a refractive index distribution (profile) as shown in FIG. 24, i.e., a step-index (SI) type optical fiber.
In addition, as an optical fiber which is capable of transmitting a larger quantity of information per unit time than the above-mentioned SI-type optical fiber, there has been proposed a graded-index (GI) type optical fiber having a refractive index distribution as shown in FIG. 25. Such a GI-type optical fiber is disclosed in Japanese Patent Publication (KOKOKU) Nos. 5857/1977 (Sho 52-5857) and 30301/1979 (Sho 54-30301), and Japanese Laid-open Patent Application (KOKAI) Nos. 130904/1986 (Sho 61-130904) and 162008/1986 (Sho 61-162008). However, these optical fibers still have various unsolved problems in view of the production thereof, etc., and an optical fiber having a desired property has not been obtained yet.
More specifically, in the conventional plastic optical fibers, since the refractive index distribution has been formed by utilizing a special chemical reaction such as one employing a difference in reactivity, and one employing a gel effect, there has been a severe limitation on the conditions such as the size of a preform, and the kind of a material, in view of the provision of a desired refractive index. Accordingly, the conventional plastic optical fibers have posed a problem such that mass production thereof is difficult or a fiber material having excellent transmission property and high reliability is difficult to be obtained.
Further, in the conventional optical fibers as described above, it is difficult to freely control the reaction for providing the refractive index distribution, and therefore it has been difficult to obtain a fiber having an ideal GI-type refractive index distribution in a good yield.
Furthermore, Japanese Laid-Open Patent Application No. 16504/1990 (Hei 2-16504) discloses a process for producing a plastic optical fiber by concentrically extruding a laminate product of two or more species of polymerizable mixtures for providing mutually different indices. However, according to the present inventors' investigation, such a process has following problems.
More specifically, since the above process is a laminating-extrusion process and it can provide extrusion steps corresponding to only about ten layers, the resultant product is inevitably caused to have a stepped-type refractive index distribution. When an optical fiber having such a stepped refractive index distribution is used, it is difficult to transmit a large quantity of information. Further, in the above process, it is suggested that a continuous and smooth refractive index distribution can be provided by further diffusing
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patent: 4692347 (1987-09-01), Yasuda
patent: 4937029 (1990-06-01), Ishiharada et al.
Ishigure et al., "Improvements in optical loss of high Bandwidth GI Polymer Optical Fiber," Polymer Preprints, Japan, vol. 41, No. 7 (1992), pp. 2942-2944. (month unknown).
Hosoya Toshifumi
Kobayashi Yuji
Matsuda Yasuo
Nonaka Tsuyoshi
Beck Shrive
Meeks Timothy H.
Sumitomo Electric Industries Ltd.
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