# US 5,703,988 A · Coated optical fiber and fabrication process therefor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,703,988 A - Document ID: US5703988A - Status: Granted - Kind: A - Application number: 08/687,497 - Filed: 1996-08-06 - Granted: 1997-12-30 - Earliest claimed: 1994-02-15 - Assignees: Sumitomo Electric Industries, Ltd. - Inventors: Kazumasa Oishi; Nobuhiro Akasaka; Tatsuya Kakuta; Yasuo Matsuda - Web page: https://patentgrep.com/patent/US5703988A ## CPC - G01M 11/088: {of optical fibres; Mechanical features associated with the optical testing of optical fibres} - C03C 25/12: General methods of coating; Devices therefor - G02B 6/02395: {Glass optical fibre with a protective coating, e.g. two layer polymer coating deposited directly on a silica cladding surface during fibre manufacture (G02B6/02052, G02B6/02057, G02B6/024, G02B6/032, G02B6/105, G02B6/14 take precedence; coating on fibre gratings G02B6/02104; multilayer core or cladding G02B6/036; reinforcing splice joints G02B6/2558; optical cables, i.e. comprising protective structures external to the protective coating such as a jacket or plural coated optical fibres G02B6/44; coating of glass to obtain optical fibres C03C25/104)} - G01M: TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR - C03C: CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS ## Abstract A coated optical fiber comprising a light-transmitting fiber and a resin coating layer disposed on the outer periphery of the light-transmitting fiber is formed, an external flaw is imparted to the surface of the resin coating layer while running the coated optical fiber, and then the coated optical fiber is subjected to the measurement of a tensile breaking strength thereof. At this time, the fiber having a strength retention ratio R.sub.S =S.sub.A /S.sub.0 of 0.98 or more, wherein S.sub.A is the median value of the tensile breaking strength after the provision of the external flaw, and S.sub.0 is the median value of the tensile breaking strength before the provision of the external flaw, is selected as a non-defective product. By using the above process for fabricating a coated optical fiber, it is possible to reduce both of the length and measuring period of time required for the evaluation of the external flaw resistance thereof, and to obtain a coated optical fiber having good characteristics while quantitatively evaluating the external flaw resistance of the fiber. ## Claims ### Claim 1 A process for fabricating a coated optical fiber, comprising: forming a coated optical fiber comprising a light-transmitting fiber and a resin coating layer disposed on the outer periphery of the light-transmitting fiber; imparting an external flaw to the surface of the resin coating layer while running the coated optical fiber, and then subjecting the coated optical fiber to the measurement of a tensile breaking strength thereof; and selecting, as a non-defective product, the fiber having a strength retention ratio R.sub.S =S.sub.A /S.sub.0 of 0.98 or more, wherein S.sub.A is the median value of the tensile breaking strength after the provision of the external flaw, and S.sub.0 is the median value of the tensile breaking strength before the provision of the external flaw. ### Claim 2 A process for fabricating a coated optical fiber, comprising: forming a coated optical fiber comprising a light-transmitting fiber and a resin coating layer disposed on the outer periphery of the light-transmitting fiber; imparting an external flaw to the surface of the resin coating layer under the application of a tension while running the coated optical fiber; and selecting, as a non-defective product, the fiber which has traveled a predetermined length without causing the breaking thereof. ### Claim 3 (depends on 1) A process for fabricating a coated optical fiber according to claim 1, wherein a body of revolution having an unevenness on its surface is caused to contact the surface of the coated optical fiber which is continuously caused to run under the application of a tension, thereby to impart the external flaw to the coated optical fiber. ### Claim 4 (depends on 3) A process for fabricating a coated optical fiber according to claim 3, wherein the body of revolution comprises a roller having a surface to which particles having a predetermined size have been attached. ### Claim 5 (depends on 3) A process for fabricating a coated optical fiber according to claim 3, wherein the body of revolution comprises a roller having a surface to which a sand paper has been bonded. ### Claim 6 (depends on 2) A process for fabricating a coated optical fiber according to claim 2, wherein the coated optical fiber is caused to run at a linear velocity of 100 m/min. to 600 m/min. ### Claim 7 (depends on 2) A process for fabricating a coated optical fiber according to claim 2, wherein the tension is 500-2000 gram-weight. ### Claim 8 (depends on 7) A process for fabricating a coated optical fiber according to claim 7, wherein the tension is 2000 gram-weight, and the fiber which has continuously traveled 1.0 km or more without causing the breaking thereof is selected as a non-defective product. ### Claim 9 (depends on 2) A process for fabricating a coated optical fiber according to claim 2, wherein a body of revolution having an unevenness on its surface is caused to contact the surface of the coated optical fiber which is continuously caused to run under the application of a tension, thereby to impart the external flaw to the coated optical fiber. ### Claim 10 (depends on 9) A process for fabricating a coated optical fiber according to claim 9, wherein the body of revolution comprises a roller having a surface to which particles having a predetermined size have been attached.