ISO 14880-4:2024

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 <70 %), surface cleaning, instrument warm‑up and calibration, and procedures for minimizing contamination and vibration.
• Procedure and reporting: stepwise measurement procedures, interpretation of results, uncertainty estimation and required content of the test report.

Applications and who uses this standard

ISO 14880-4 is intended for:

• Optical component manufacturers and suppliers of microlens arrays for quality control and product specification.
• Metrology and calibration laboratories performing traceable geometric measurements of microlenses.
• R&D teams designing microlens arrays for 3D displays, arrayed light sources/detectors, LCD enhancement, optical coupling and parallel photonic processors.
• System integrators and procurement professionals specifying acceptance criteria and verifying supplier claims.

Practical benefits include consistent measurement practice, reduced disputes over geometrical specs (pitch, sag, thickness, curvature), and improved interchangeability of microlens arrays across suppliers and applications.

Related standards

• ISO 14880-1 (vocabulary and characteristic parameters)
• ISO 14880-2, ISO 14880-3 (other parts of the microlens array series)
• ISO 21920-2:2021 (surface texture / roughness profile terminology referenced)