Outdoor Finished Optical Cable Grinding

Outdoor optical fiber cables are typically finished using a multi-step grinding and polishing process to ensure low insertion loss, minimal backreflection, and durable end-face quality.

Step-by-Step Grinding and Polishing Process

1. Deburring and Epoxy Removal Before polishing, the fiber end must be prepared by removing protective coatings and any adhesive used to fix the fiber in a ferrule. For ceramic ferrules, carbon silicon carbide grinding sheets (e.g., SC30/15) are commonly used to remove epoxy and shape the ferrule end face . This step ensures a clean surface for subsequent grinding. 2. Coarse Grinding Coarse grinding removes a significant amount of material quickly and shapes the fiber end. Diamond grinding sheets of varying grit sizes (D9, D6, D3) are used depending on the fiber type and connector requirements . For angled physical contact (APC) connectors, a large-grit sheet is used to create the required 8° angle. 3. Semi-Fine Grinding This step refines the end face, reducing surface roughness. Finer diamond sheets (D1) are used to prepare the fiber for final polishing . The goal is to achieve a smooth, convex or flat surface depending on the connector type. 4. Fine Grinding and Polishing Fine grinding with ultra-fine diamond sheets (e.g., D0.5) is followed by polishing using polishing pads and liquids such as cerium oxide . For single-fiber connectors, a slightly convex surface is preferred, while multi-fiber MT/MPO connectors require a flat end-face with all fibers protruding uniformly . Polishing can be done by hand for small-scale work, but machines provide higher consistency and precision. 5. Inspection and Quality Control After polishing, the fiber end must be inspected under a microscope (200–400x magnification) to check for scratches, defects, and proper geometry . Key parameters include apex offset, radius of curvature, and fiber protrusion. High-quality finishes minimize backreflection and insertion loss, critical for outdoor applications where environmental conditions can affect signal integrity.

Additional Considerations for Outdoor Cables

• Environmental Durability: Outdoor fibers must withstand temperature fluctuations, moisture, and mechanical stress. Proper polishing ensures the end-face remains stable under these conditions.
• Connector Type: APC, UPC, and PC finishes are chosen based on system requirements. APC is preferred for high-bandwidth outdoor links due to its low backreflection .
• Cleaning: Use deionized water, isopropyl alcohol, canned air, and lint-free swabs to remove debris before and after polishing . Contamination can significantly degrade performance. By following this multi-step grinding and polishing method, outdoor optical fiber cables achieve high-quality end faces, ensuring reliable signal transmission and long-term durability in harsh environments.