ISO 14880-2:2006

Overview

ISO 14880-2:2006 - "Optics and photonics - Microlens arrays - Part 2: Test methods for wavefront aberrations" specifies standardized methods to measure and report the wavefront aberrations of microlenses formed on a common substrate (microlens arrays). The standard defines the test principle, required apparatus, measurement arrangements for single microlenses and whole arrays, evaluation techniques, accuracy considerations and the contents of a compliant test report. It is intended for very small lenses formed inside or on one or more surfaces of a shared substrate.

Key topics and technical requirements

• Scope and terminology: Uses terms defined in ISO 14880-1 (Vocabulary).
• Apparatus: Test systems typically include a standard optical radiation source, collimator, standard lens (reference), beam-reduction optics, aperture stop, imaging optics, image sensor and an interference pattern analyser.
• Source and reference quality: The incident wavefront on the test equipment should have low aberration (example targets in the standard: source wavefront rms ~λ/10; collimator aberrations <λ/20; reference lens aberrations at least one order of magnitude smaller than the test lens or ~λ/10 rms).
• Test principle: Wavefronts are measured using interferometers or wavefront sensors in transmitted radiation; single-pass geometries are preferred to reduce spurious fringes.
• Methods described in annexes:
  • Mach–Zehnder interferometer methods (Annex B)
  • Lateral shearing interferometer methods (Annex C)
  • Shack–Hartmann sensor method (Annex D)
  • Twyman–Green interferometer array tests (Annex E)
  • Uniformity measurements for arrays (Annex F)
• Measurement arrangements: Guidance for single-lens spot testing and simultaneous testing of parts or whole arrays. Emphasis on careful geometrical alignment and environmental control (temperature, vibration).
• Evaluation: Wavefronts derived from interferograms or sensor data; extraction of Zernike coefficients (spherical, coma, astigmatism) and reporting as RMS or peak-to-valley (P-V) values (recommended practice: favor 6×rms over raw P-V due to sensitivity to outliers).
• Reporting and accuracy: Specifies what to record about source, optics, aperture, measurement geometry and uncertainty.

Applications and users

ISO 14880-2 is directly applicable to:

• Optical engineers and designers of microlens arrays for 3D displays, arrayed light coupling (LED/photodiode arrays), enhanced LCD optics and optical parallel processing.
• Manufacturers and quality assurance/metrology labs performing wavefront measurement and acceptance testing.
• Research labs developing microlens fabrication processes and optical metrology systems.

Related standards

• ISO 14880-1: Vocabulary (part 1)
• ISO 14880-3: Test methods for optical properties other than wavefront aberrations
• ISO 14880-4: Test methods for geometrical properties
• ISO/TR 14999-2 is referenced for extended measurement guidance.

Keywords: ISO 14880-2, microlens arrays, wavefront aberrations, interferometer, Shack–Hartmann, Mach–Zehnder, Twyman–Green, optical testing, wavefront measurement.