ISO 14880-3:2024

Overview - ISO 14880-3:2024 (Microlens arrays test methods)

ISO 14880-3:2024 specifies standardized test methods for the optical properties (other than wavefront aberrations) of microlenses in microlens arrays, including very small surface-relief lenses and graded‑index microlenses. The standard focuses on measurable quantities such as effective back/front focal length, chromatic behaviour, focal-spot uniformity, coupling efficiency and imaging quality. It complements ISO 14880-1 (vocabulary) and works with other parts of the series that address wavefront and non‑optical characteristics.

Key topics and technical requirements

• Scope and applicability: Applies to microlens arrays formed on one or more surfaces of a common substrate and to graded‑index microlenses.
• Substrate test: Optical substrate quality contributes to focal‑position accuracy and shall be quantified per ISO 10110-5.
• Microscope technique (primary method):
  • Principle: locate lens surface/vertex optically and determine effective back/front focal length from axial displacement to focus on an image of a distant source.
  • Test system: microscope with focusing aid (e.g., split‑field), calibrated displacement transducer, suitable light source, test graticule or illuminated fibre, video camera and image analyser.
  • Requirement: microscope objective NA must exceed the microlens NA at the focal point.
  • Environmental/control: temperature‑controlled, vibration‑free conditions (recommended ~20 °C); clean optical surfaces.
• Interferometry and wavefront‑sensing alternatives: Annex A covers interferometric techniques (e.g., Fizeau, Twyman‑Green) and Annex D describes Shack‑Hartmann methods for focal‑spot mapping.
• Additional methods: Annex B describes confocal measurement of focal length; Annex C discusses coupling efficiency and imaging quality evaluation.
• Calibration and reporting: Use calibration artefacts (known microlens focal length, step‑height standards); report light source properties, measurement uncertainties and test conditions.

Practical applications and users

Who benefits:

• Optical engineers and metrology laboratories validating microlens performance
• Manufacturers of microlens arrays (quality control, acceptance testing)
• System integrators in displays, imaging, 3D displays, VCSEL and detector coupling, and optical parallel processors
• R&D teams developing graded‑index or micro‑optical components

Why use it:

• Ensures repeatable, comparable measurements of focal length, chromatic behavior, focal‑spot uniformity, coupling efficiency and imaging quality
• Improves interchangeability between suppliers and confidence for integration into photonics systems

Related standards

• ISO 14880-1 - Vocabulary and characteristic parameters
• ISO 14880-2 - Wavefront aberrations (related optical properties)
• ISO 14880-4 / ISO/TR 14880-5 - Other series parts addressing complementary topics
• ISO 10110-5 - Surface form tolerances (substrate testing)