ISO 14880-4:2024 PDF

Overview

ISO 14880-4:2024 - "Optics and photonics - Microlens arrays - Part 4: Test methods for geometrical properties" specifies standardized methods for measuring the geometric characteristics of microlenses in microlens arrays. It applies to arrays of very small lenses formed on one or more surfaces of a common substrate and to graded‑index microlenses. The standard is part of the ISO 14880 series and focuses on metrology methods to ensure compatibility, interchangeability and reliable specification of microlens array components.

Key topics and requirements

• Measured parameters: pitch (Px, Py), surface modulation depth (h, also referred to as lens sag), physical thickness (Tc), and radius of curvature (Rc).
• Coordinate system: right‑handed Cartesian system with X and Y in the substrate plane and Z outward from the material.
• Primary test methods:
  • Stylus profilometer: profile acquisition through lens centers; guidance on stylus tip geometry, contact force, environmental control, calibration and avoiding surface damage. Typical tip shapes suggested are conical with spherical tips (cone angles ~60° or 90°, tip radii 1 µm, 2 µm, 5 µm or 10 µm).
  • Confocal microscopy: non‑contact surface topography by focus scanning and intensity detection for depth discrimination.
• Supporting methods / annexes:
  • Annex A: measurement using a Fizeau interferometer system (informative).
  • Annex B: analysis of array spacing uniformity (informative).
• Measurement conditions and preparation: environmental recommendations (approx. 20 °C ± 5 °C, humidity