ISO 14880-4:2006

Overview

ISO 14880-4:2006 - "Optics and photonics - Microlens arrays - Part 4: Test methods for geometrical properties" specifies standardized methods for measuring the geometrical properties of microlenses in microlens arrays. It applies to very small lenses formed on one or more surfaces of a common substrate and to graded‑index microlenses. The standard supports consistent quality assessment and interchangeability of microlens arrays used in photonics and micro‑optics.

Key topics and technical requirements

• Measured parameters: pitch (Px, Py), surface modulation depth (h) (lens sag), physical thickness (Tc) and radius of curvature (Rc). These are defined using a Cartesian coordinate system (x, y in substrate plane; z outward).
• Primary test methods:
  • Stylus profilometry: obtain surface profiles that pass through lens centres to determine pitch and sag. Guidance covers stylus tip geometry (ideal cone with spherical tip; cone angles commonly 60° or 90°; tip radii examples 1, 2, 5 or 10 µm), contact force control, instrument stabilization and calibration.
  • Confocal microscopy: non‑contact surface topography via focus discrimination (including Nipkow‑disc/microlens‑disc or microlens + pinhole array configurations) for fast, high‑resolution mapping.
  • Micrometer measurement: contact measurement of local physical thickness (anvil types, calibration and thermal stabilization).
  • Radius of curvature measurement: optical locating of the vertex, focal position or centre of curvature (suitable for spherical surfaces; interferometry for non‑spherical/zonal analysis).
• Ancillary requirements: environmental control (recommended ambient ~20 °C ±5 °C, humidity <70 % without condensation), instrument calibration, stylus inspection, surface cleaning and preparation.
• Annexes: includes normative guidance for Fizeau interferometer measurements (Annex A) and informative notes on array spacing uniformity (Annex B).
• Reporting: procedures for results, uncertainties and test reports are specified.

Practical applications

ISO 14880-4 is directly applicable to:

• Design verification and quality control of microlens arrays used in:
  • three‑dimensional displays and imaging systems
  • coupling optics for arrayed light sources and photodetectors
  • enhanced optics for liquid‑crystal displays (LCDs)
  • optical parallel processors and micro‑optical assemblies
• Test laboratories, OEMs and suppliers requiring repeatable, comparable geometric measurements for production acceptance, R&D and supplier qualification.

Who should use this standard

• Optical engineers and metrology specialists
• Micro‑optics and photonics manufacturers
• Quality assurance and test laboratories
• R&D groups developing microlens arrays or graded‑index micro‑optics

Related standards

• ISO 14880-1 (Vocabulary)
• ISO 14880-2 (Wavefront aberration test methods)
• ISO 14880-3 (Optical properties other than wavefront aberrations)
• ISO 4287 (surface texture terminology and parameters referenced)

Keywords: ISO 14880-4, microlens arrays, test methods, geometrical properties, pitch, surface modulation depth, radius of curvature, stylus profilometry, confocal microscope, Fizeau interferometer, optics and photonics.