Overview
IEC 61315:2019 - “Calibration of fibre‑optic power meters” - is the international standard that specifies how to calibrate instruments that measure optical (radiant) power used in the fibre‑optic communications industry. It applies to sources typical for the industry (laser diodes, LEDs and fibre‑type sources) and covers both divergent and collimated radiation. The third edition (2019) replaces the 2005 edition and introduces updated terms and definitions, revisions to calibration methods (Clause 5.1 and Table 1), an updated uncertainty Annex A, and a new Annex B on dB conversion.
Key topics and technical requirements
- Scope of calibration: Defines calibration conditions (how the source, geometry and connectors are described) and requires these to be recorded with the calibration result.
- Absolute power calibration (Clause 5): Establishes the correction factor between input optical power and the power‑meter reading.
- Traceability and preparation: Sets out requirements for traceability chains, laboratory organization and recommendations to customers.
- Measurement uncertainty (Clauses 5.4 & 6): Provides methods to evaluate uncertainty contributions from reference meters, the test meter, the setup and procedural effects. Annex A gives the mathematical basis for uncertainty calculation.
- Nonlinearity (Clause 7): Specifies procedures to determine and report detector nonlinearity (superposition, comparison methods, attenuator methods).
- Dependence on conditions: Addresses how response depends on wavelength, spectral bandwidth, polarization, temperature, connector/adapter combinations, beam geometry and ageing.
- Reporting: Requires calibration reports to include correction factors, stated calibration conditions, traceability and uncertainty. Annex B explains conversion of linear uncertainties to dB values.
Practical applications
- Ensures reliable, traceable optical power measurements for production testing, field verification and research.
- Used by manufacturers to qualify power‑meter designs and to supply calibrated instruments.
- Used by metrology and calibration laboratories to provide accredited calibration services.
- Applied in telecom equipment manufacturing, installation/commissioning of fibre networks, lab characterization of optical components, and quality management systems requiring traceable optical power data.
Who should use this standard
- Calibration laboratories and national metrology institutes
- Fibre‑optic power‑meter manufacturers
- Test engineers, field technicians and QA managers involved in optical power measurements
- R&D teams working on detectors, sources and optical test equipment
Related standards and context
- Prepared by IEC Technical Committee 86 (Fibre optics). The document follows ISO/IEC Directives for standards development. For terminology, see IEC Electropedia and related IEC publications.
Note: IEC 61315:2019 reminds users that optical power measured in air at a fibre end is about 3.6% lower than in the fibre due to Fresnel reflection (N = 1.47), an example of the measurement‑condition dependence the standard addresses.