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