To help you get started with a specific fiber optic polishing procedure

Polishing a fiber optic connector is a critical process designed to ensure that light can travel from one fiber to another with minimal loss (insertion loss) and reflection (return loss). Because the glass core of a fiber is incredibly small (typically 9 to 62.5 microns), the end surface must be polished to a mirror finish with sub-micron precision.

The 4-Step Polishing Process

Most professional "recipes" for polishing ceramic (Zirconia) or stainless steel ferrules follow this general progression.

To help you get started with a specific fiber optic polishing procedure, here are the step-by-step instructions for the two most common types of connectors.

Comparison: UPC vs. APC Polishing

The primary difference lies in the shape of the ferrule tip, which dictates how light reflects back toward the source.

Step-by-Step Procedure for UPC (Blue) Connectors

This method uses a standard 90-degree polishing puck and a rubber pad to create a "Physical Contact" dome.

1. Preparation:

   • Clean your glass plate and place the 5mm or 6mm rubber pad on top.

   • Clean the lapping film and the rubber pad with 99% Isopropyl Alcohol (IPA) and a lint-free wipe.

2. Step 1: De-nubbing (30 um Silicon Carbide):

   • Place the 30 um film on the plate.

   • Gently touch the connector to the film and perform a "figure-8" motion with zero pressure until the glass "nub" is gone.

   • Clean the connector and inspect with a scope.

3. Step 2: Shaping (9 um Diamond):

   • Place the 9um film on the rubber pad.

   • Add a few drops of distilled water.

   • Perform 10–15 figure-8 motions using moderate, even pressure. This begins forming the dome.

   • Clean and inspect for the removal of the 30 um scratches.

4. Step 3: Intermediate (1 um Diamond):

   • Place the 1 um film on the pad.

   • Perform 10 figure-8 motions. This should leave a very faint, uniform scratch pattern.

   • Critical: Clean the puck and connector thoroughly to ensure no 1 um grit reaches the final stage.

5. Step 4: Final Polish (0.02 um Silica / Final Film):

   • Use a fresh "Final Polish" film (usually white or pale green).

   • Use plenty of distilled water.

   • Perform 5–10 figure-8 motions with very light pressure.

   • Clean and inspect. The end-face should look like a flawless mirror.

Common Troubleshooting

• Pitting (Small black dots in the center): Usually caused by dirt or contamination during the final steps. Ensure your water is distilled.

• Scratches (Lines across the fiber): You likely didn't polish long enough in the previous step, or a larger grit particle contaminated a finer film.

• Shattered Core: You applied too much pressure during the initial "de-nubbing" stage.