Overview
EN ISO 11551:2019 (Corrected version 2020-01) - adopted by CEN - defines a calibrated, reproducible test method for absorptance of optical laser components. The standard specifies procedures to obtain comparable values of absorptance by calorimetric measurement: absorptance is reported as the ratio of radiant flux converted into heat and absorbed by the component to the incident radiant flux. The method assumes absorptance remains effectively constant during the temperature changes experienced in the test and notes that only thermally converted absorption is measured (non‑thermal processes are not detected).
Key topics and technical requirements
- Scope and definition of absorptance specific to laser‑related optics.
- Test sample preparation and measuring arrangement - environmental and sample handling considerations for reliable results.
- Characterization of laser radiation used for the test (beam parameters and stability).
- Calibration procedures:
- Calibration of power and temperature signals.
- Calibration of the thermal response of the sample/holder.
- Measurement and subtraction of background signals.
- Test procedures for continuous and pulsed operation, including requirements for drift control and heating limits.
- Data evaluation methods:
- Drift elimination techniques.
- The exponential method and pulse method for extracting absorptance from temperature-time data.
- Reporting requirements specifying necessary information in the test report.
- Informative annexes covering effects that change absorptance, signal distortions and a parameterization algorithm for temperature data.
Practical applications
- Quantifying heat load from laser irradiation on optical components (lenses, mirrors, windows, coatings).
- Supporting component specification, acceptance testing and quality control where laser-induced heating is a concern.
- Informing design decisions for thermal management and assessing suitability of materials/components for high-power laser systems.
- Providing comparable absorptance data for suppliers, test laboratories and research groups working in optics and photonics.
Who uses this standard
- Optical component manufacturers and coating vendors
- Laser system designers and integrators
- Test laboratories and calibration facilities
- R&D groups in photonics and materials science
- Procurement and quality assurance teams requiring standardized absorptance data
Related standards (normative references)
Keywords: EN ISO 11551, ISO 11551:2019, absorptance measurement, optical laser components, calorimetric test method, lasers, photonics, absorptance standard.