Overview
ISO 14999-4:2015 - "Optics and photonics - Interferometric measurement of optical elements and optical systems - Part 4" - provides formal guidance for interpreting interferometric data used to evaluate surface form deviation and wavefront deformation against tolerances specified in ISO 10110 (notably ISO 10110‑5 and ISO 10110‑14). The 2015 second edition expands coverage to cylindrical/torical wavefronts, defines key optical functions and values, and gives practical procedures (including visual interferogram analysis) for reducing and evaluating interferometric measurements. The standard prefers SI units (nanometres) and explains scaling between single‑pass and double‑pass test arrangements.
Key topics and technical requirements
- Terms and mathematical definitions: precise definitions of peak‑to‑valley (PV), root‑mean‑square (rms), and measured wavefront deformation.
- Function decomposition: standardized functions used to represent interferometric data, e.g., tilt, twist, wavefront spherical/cylindrical approximations, wavefront irregularity, and rotational/translational deviations.
- Values related to functions: how to derive and report power deviation (formerly called sagitta deviation), irregularity (PV values), and cylindrical power components (AX, AY equivalents).
- Wavefront representation: guidance for expressing measured deviations as Zernike coefficients (Annex B) and for converting measurements between wavelengths (Clause 4.6).
- Slope deviation tolerancing: procedures for one‑dimensional and two‑dimensional slope deviation measurement and evaluation.
- Visual interferogram analysis: normative guidance for visual interpretation of interferograms (Annex A).
- Measurement context: guidance on relating interferometric measurements to surface form or transmitted wavefront deformation for single‑pass and double‑pass setups.
Practical applications - who uses ISO 14999-4
- Optical manufacturers (lenses, mirrors, aspheres, toroids) for acceptance testing and drawing interpretation.
- Metrology laboratories performing interferometric quality control and certification.
- Optical designers and systems engineers needing consistent interpretation of ISO 10110 tolerances.
- Research & development teams and precision‑manufacturing quality assurance groups requiring standard methods for converting interferograms into actionable tolerance metrics.
Benefits include consistent reporting of PV and rms values, unambiguous conversion between wavefront and surface metrics, and standardized decompositions (including Zernike) for further analysis or specification compliance.
Related standards
- ISO 10110‑5 - Preparation of drawings: surface form tolerances
- ISO 10110‑14 - Preparation of drawings: wavefront deformation tolerances
- ISO/TR 14999‑2 - Interferometric measurement techniques (measurement and evaluation)
- Other parts of ISO 14999 (Parts 1–3) covering terminology, measurement techniques, and calibration.
Keywords: ISO 14999-4, interferometric measurement, optical elements, optical systems, ISO 10110, wavefront deformation, surface form deviation, Zernike coefficients, power deviation, visual interferogram analysis.