Overview
EN ISO 11146-1:2021 (ISO 11146-1:2021) specifies standardized test methods for characterizing laser beams - in particular beam widths (diameter), divergence angles and beam propagation ratios - for stigmatic and simple astigmatic beams. The standard defines measurement principles based on the method of second order moments (within the paraxial approximation), the required measurement arrangements, detector and optics considerations, and the content of the test report. For beams of unknown type or for general astigmatic beams, ISO 11146-2 applies.
Key Topics and Requirements
- Scope and applicability: Measurement methods are limited to stigmatic and simple astigmatic beams; other beam types are covered in ISO 11146-2.
- Measurement principle: Beam characterization uses second order moments of the power (energy) density distribution to define beam widths and propagation parameters.
- Coordinate systems and principal axes: The standard clarifies coordinate definitions (including principal axes x' and y') used in evaluations.
- Test arrangement and equipment: Requirements for detector systems, beam-forming optics, optical attenuators, focusing systems and environmental controls are specified to ensure repeatable, traceable measurements.
- Measurement procedures: Step-by-step procedures for measuring beam width, divergence angle and combined determination of beam waist, beam widths, divergence and beam propagation ratio (M2) are provided.
- Evaluation and reporting: Guidelines for data evaluation, integration ranges for second order moments (note: integration requirements were relaxed in this edition), and minimum test-report content are included.
- Alternatives and correlation: ISO/TR 11146-3 describes alternative beam width measurement methods (variable aperture, moving knife-edge, moving slit) and their correlation with the second-moment method.
Practical Applications and Users
This standard is essential for professionals who need reliable, comparable laser beam characterization:
- Laser manufacturers - specification, QA and production testing of laser sources.
- Test and calibration laboratories / metrology institutes - standardized measurement procedures for traceable results.
- Optical system integrators and R&D teams - beam quality (M2), divergence and waist location for system design and simulation.
- Medical, industrial and telecommunications engineers - performance verification for processing, imaging and free-space links.
- Regulatory and safety specialists - supporting documentation for compliance and safety assessments.
Using EN ISO 11146-1:2021 helps ensure consistent, repeatable measurement of critical beam parameters, improving product specifications, process control and interoperability across photonics applications.
Related Standards
- ISO 11146-2 - General astigmatic beams (when beam type is unknown or more complex).
- ISO/TR 11146-3 - Technical report on theoretical background and alternative methods.
- ISO 11145 - Vocabulary and symbols (harmonized terms).
- ISO 13694 - Power (energy) density distribution test methods.