IEC 61757-8-1:2025

Overview

IEC 61757-8-1:2025 - "Fibre optic sensors - Part 8-1: Pressure measurement - Pressure sensors based on fibre Bragg gratings" is an international standard from the IEC that defines terminology, structure, and measurement methods for fibre optic pressure sensors that use a diaphragm combined with fibre Bragg gratings (FBGs). The standard specifies the main features and characteristics of these FBG pressure sensors and provides procedures for measuring and reporting those characteristics, enabling consistent evaluation, calibration and comparison.

Key topics and technical requirements

• Terminology and symbols: Standardized definitions for pressure, FBG pressure sensor, pressure conversion factor and related symbols to ensure consistent communication.
• Sensor structure and configuration: Description of FBG configurations, diaphragm-based transduction, reference wavelength concepts and typical sensor types.
• Measurement procedures:
  • Bragg wavelength (λ) measurement and reporting
  • FBG spectral width and reflectivity test methods
  • Pressure measurement setups (including dead-weight testers and schematic test arrangements)
  • Pressure conversion factor (κ) determination
• Performance characteristics and evaluation:
  • Stability behaviour (drift, creep, hysteresis)
  • Sampling, statistical evaluation and reporting of results
  • Calibration and uncertainty considerations aligned with GUM principles
• Environmental limits and durability:
  • Temperature and humidity ranges for storage, transport, installation and operation
  • Durability and conditioning tests (sampling, ambient test conditions)
• Documentation and reporting:
  • Required construction details, sensor series/type definitions, connection requirements and recommended reporting formats
• Recommended instrumentation: Guidance on FBG measurement instruments, wavelength calibration and optical spectrum analyzers.

Practical applications

IEC 61757-8-1:2025 is directly applicable to industries and applications that require precise, reliable optical pressure sensing, including:

• Oil & gas and chemical process monitoring (corrosive or electromagnetic-interference prone environments)
• Aerospace and automotive systems where compact, high-temperature or EMI-immune sensors are needed
• Medical devices and laboratory instrumentation for liquid and gas pressure measurement
• Industrial automation, structural health monitoring and subsea sensing

Using the standard helps manufacturers, test labs and sensor integrators to design, qualify, calibrate and document fibre optic pressure sensors consistently and to specify performance requirements for procurement and verification.

Who should use this standard

• Sensor manufacturers and R&D teams designing FBG-based pressure sensors
• Calibration and testing laboratories performing qualification or type testing
• System integrators and OEMs specifying sensor performance and environmental requirements
• Standards and quality engineers establishing acceptance criteria and documentation

Related standards

• IEC 61757 (generic fibre optic sensors series)
• IEC 61757-1-1:2020 (FBG strain sensors - terminology and methods)
• IEC 60068-2 (environmental testing)
• IEC 62129-1 / -2 (calibration of wavelength measurement instruments)
• ISO/IEC Guide 98-3 (GUM - uncertainty of measurement)

Keywords: IEC 61757-8-1:2025, fibre optic pressure sensors, fibre Bragg gratings, FBG pressure sensor, pressure measurement, diaphragm-based FBG sensors, Bragg wavelength, pressure conversion factor, sensor calibration.