IEC 61300-3-35:2015

Overview

IEC 61300-3-35:2015 defines standardized visual inspection and quantitative assessment methods for the end face quality of a polished fibre optic connector and for fibre optic transceivers using a fibre‑stub type interface. The standard prescribes procedures to inspect ferruled 125 µm cladding fibres (intended for sources ≤ 2 W input power), and identifies portions that also apply to non‑ferruled connectors and other fibre types. Sub‑surface cracks and fractures are explicitly excluded. This second edition (2015) updates terminology, visual requirement tables and adds specific requirements for single‑mode transceivers with fibre‑stub interfaces.

Key topics and requirements

• Scope and limits: Focus on surface defects (scratches, pits, debris, chips); sub‑surface defects not covered. Intended primarily for 125 µm cladding fibres and ≤ 2 W sources.
• Inspection philosophy: Defect presence is estimated visually - the standard does not require measuring scratch widths to micron precision (e.g., no need to measure 2.3 µm).
• Measurement methods: Three main apparatus/methods are defined:
  • Method A - Direct view optical microscopy
  • Method B - Video microscopy
  • Method C - Automated analysis microscopy
• Calibration and certification: Requirements for low‑ and high‑resolution microscopy systems and artefacts (annexes provide calibration artefact diagrams and manufacture methods).
• Procedure elements: Defined measurement regions (single‑fibre and multi‑fibre ferrules), inspection flow, pre‑conditioning and recovery, and visual acceptance criteria organized in tabular form (Tables 1–6). Table 3 now includes visual requirements for single‑mode fibre‑stub transceivers.
• Detectability: Defects must be “reliably detectable” - visible to a typically trained technician ≥98% of the time.
• System variability: The standard notes susceptibility of methods to system variability and recommends appropriate control/calibration.

Practical applications

• Incoming inspection and production QC for connectorized fibre assemblies, transceivers and ferrules.
• Acceptance testing for polished connectors and fibre‑stub transceivers prior to installation or shipment.
• Field troubleshooting and maintenance to verify end‑face cleanliness and damage prior to mating (reduces risk of connector damage or optical loss).
• Automation integration where Method C (automated analysis microscopy) is used for high‑throughput manufacturing inspection.

Who should use this standard

• Fibre optic component manufacturers and transceiver vendors
• Quality assurance and test laboratories
• Network installers and maintenance teams in telecommunications, datacom, military and industrial optical systems
• Equipment designers specifying end‑face visual acceptance criteria

Related standards

IEC 61300‑3‑35 is part of the IEC 61300 series (basic test and measurement procedures) and is intended to be used with other IEC 61300 parts that set maximum allowable surface defects and optical performance limits.