Check what the datum represents
The word “concentricity” on a fiber certificate and a ferrule report may refer to different objects. Inspect the centers, axes and specimen state on the drawing. Matching micrometer units alone do not make two quantities comparable.
ITU-T G.650.1 defines core concentricity error as the distance between core and cladding centers, separately from mode-field definitions.1 That fiber attribute does not directly specify where the core lies against the external ferrule datum after assembly.
Separate the geometry fields
| Field | Object and reference | Suggested evidence |
|---|---|---|
| Core/cladding concentricity | Centers within the raw fiber | Fiber identity and inspection record |
| Bare-ferrule concentricity | Bore axis against ferrule axis | Drawing, datum and method |
| Fiber-installed concentricity | Core axis against ferrule axis | Measurement in assembled state |
| Angular error | Direction difference between defined axes | Angular units and axis datums |
| Endface geometry | Shape and position in the contact region | Interface-specific endface report |
IEC 61300-3-25 distinguishes a bare ferrule's bore axis from the core axis of a fiber-installed ferrule, referenced to the ferrule axis.2 State whether the order covers a component or a fiber-installed part and ask which state the report represents.
Retain angular and lateral results separately
IEC 61300-3-54 describes angular misalignment between a cylindrical ferrule bore axis and its outside-diameter datum axis.3 Angular and length values need separate units and criteria rather than one comparison column.
Specify the datum, gripping condition and measurement method on the drawing. Where a report uses a different representation convention, obtain an explicit mapping to the drawing field. Do not convert by name alone. Keep batch and sampling identities so one specimen image does not stand in for an entire lot.
For rework or fiber substitution, retain material batches and determine whether the approved geometry and optical verification remain applicable. These records support review without assuming one material necessarily creates a specific loss outcome.
Match the method to the interface
IEC 61755-3-1:2024 concerns defined singlemode, non-angled cylindrical zirconia interfaces. Its revision summary includes core eccentricity distributions and mean-value descriptions.4 Read scope conditions with the order. A cylindrical-ferrule report does not qualify a rectangular multifiber interface.
| Review task | Check | Purchasing decision |
|---|---|---|
| Raw fiber | Identity, definition and batch | Suitability of material attributes |
| Component | Bore, external axis and datum | Correspondence to the drawing |
| Assembly | Fiber-installed state and revision | Completed geometry verification |
| Method suitability | Interface shape, polish and scope | Applicability to the specimen |
| Optical confirmation | Mating parts, wavelength and setup | Actual connection performance |
Geometry evidence can explain assembly conditions. Include the agreed optical tests in complete connection acceptance as well. Keep microscopy, concentricity and insertion-loss records identifiable to help locate where a difference arose.
Procurement FAQ
- Does a compliant raw fiber remove assembly testing? Review the installed state and agreed optical results separately from material certification.
- Can a bare-ferrule report replace an assembled report? Check the tested axes and specimen state; an empty bore and an installed core are different objects.
- Can angular error be compared directly in micrometers? Establish the defined quantity and units rather than combining different measurements informally.
- Can cylindrical-ferrule limits be transferred to MPO? Use methods and requirements applicable to the rectangular multifiber interface.
- Does finer geometry guarantee a specified insertion loss? Obtain finished optical results under defined mating and measurement conditions.
Related products and further reading
Use custom ferrules to organize drawings and assembly boundaries. See mode-field versus core diameter and MPO endface geometry evidence for adjacent decisions.
Contact an engineer
Send the drawing, fiber specification and existing reports through the engineering contact to discuss measurement objects, datums and sample requirements. Processing tolerances depend on the reviewed specification.
Sources and review date
Checked on 2026-10-31. This guide interprets definitions and method scope without prescribing universal machining limits or ARRANEX tolerances.
Sources checked: 2026-10-31