Practical Laser Repair

In fiber laser source repair, S37 LDF fiber optic splicers and LDC100 large diameter fiber cleavers are essential tools. To ensure optimal performance of the splicer and cleaver, the matching of the fiber optic insert (clamp adapter) is crucial. Choosing the wrong insert can lead to unstable fiber mounting, or even severe issues like misaligned ends and significantly increased splice loss. Today, we'll explain in detail how to accurately measure the fiber cladding diameter using a micrometer on-site and then replace it with the appropriate insert according to the specifications.

I. Why Measure the Cladding Diameter First?

The structure of an optical fiber consists of a core, cladding, and coating. The V-groove and clamping feet (i.e., the insert) of the splicer and cleaver directly contact the cladding (typically 125μm in diameter), not the thick fiber containing the coating. Different laser models may use special fibers (such as 80μm cladding, large mode field diameter fibers, etc.). Blindly replacing the insert not only fails to clamp properly but may even crush the fiber. Therefore, the first step is always to measure the cladding.

II. Tool Preparation

* Digital micrometer (accuracy 0.1μm, or at least 1μm)

* Fiber stripping pliers (for removing the coating)

* Cleaning paper, alcohol (for cleaning the fiber)

* Insert specification table for the corresponding fusion splicer/cleaver (available from the equipment manual or manufacturer)

* Spare insert kit

III. Detailed Operating Procedures

* 1. Remove the coating and clean

* Carefully remove approximately 10mm of the coating from the end of the fiber to be tested using the fiber stripping pliers, exposing the glass cladding. Be careful not to scratch the glass surface. Then gently wipe it clean with cleaning paper dampened with alcohol.

* 2. Measure the cladding diameter with the micrometer

* Place the exposed cladding and coating portion horizontally between the anvil and micrometer screw of the micrometer.

* Slowly rotate the ratchet until you hear a "click" sound (avoid crushing the fiber).

* Read the value. It is recommended to measure 3 times at different angles and take the average value.

Common cladding diameter references: 125μm for standard single-mode fiber, 80μm, 100μm, 200μm, etc. for some specialty fibers.

3. Consult the insert specification table.

Select the corresponding insert model based on your measured value. If a non-standard value is measured (e.g., 128μm), it indicates the fiber is not clean or the micrometer is not calibrated; re-clean and measure.

4. Replace the insert.

Fusion splicer side: Open the clamping arm and remove the old insert (usually secured magnetically or with clips). Insert the new insert into the positioning slot, ensuring the V-groove is aligned with the optical path.

Cleaver side: Loosen the fixing screws on the cleaver holder and remove the old insert. Clean the cleaver holder base and install the new insert, ensuring the clamping foot is parallel to the cleaver's mating surface.

After replacement, a small section of the same fiber can be used for clamping testing: the fiber should be gently clamped, and there should be uniform resistance without wobbling when pushed axially.

IV. Why must the fusion splicer and cleaver inserts be replaced simultaneously?

Before fusion splicing, the end face needs to be prepared with a cleaver, and then the fusion splicer is used. If the cleaver uses a 125μm insert, while the fusion splicer uses an 80μm insert, the clamping height of the fiber on the two devices will be inconsistent, resulting in fiber core misalignment during splicing. Always replace them in pairs to ensure that the clamping geometry of the two tools is perfectly matched.

V. On-site maintenance tips

Zeroing the micrometer before use: Close the anvil and check for zero drift.

Handling with care: The glass cladding is extremely fragile; do not apply excessive force during measurement.

Regular cleaning of the inserts: Dust in the V-groove directly affects splice loss; wipe it with a special cotton swab dipped in alcohol when replacing the insert.

Keeping a replacement log: Record the fiber type, cladding diameter, and insert model used after each maintenance for future traceability.

VI. Summary Replacing fiber optic inserts may seem like a small task, but it directly impacts the success or failure of laser repair. Remember the principle of "one measurement, two checks, three replacements":

One measurement: Accurately measure the bare cladding diameter with a micrometer.

Two checks: Select the correct model according to the insert specification table.

Three replacements: Replace the fusion splicer and cleaver simultaneously, and verify the clamping action.

Mastering this skill will allow you to handle both emergency laser repairs in the workshop and on-site splicing of special fibers with ease, ensuring every splice achieves a professional level of low loss and high strength.

Note: If you do not have the manufacturer's insert specification table, you can contact your equipment supplier to obtain it, or consult a compatible third-party insert based on the cladding diameter—but always conduct a small-scale test first to avoid damaging the equipment.

We hope this practical guide has been helpful. In the next installment, we will continue discussing fiber end-face inspection techniques in laser optical path calibration. Stay tuned!