Overview
ISO 15795:2002 - "Optics and optical instruments - Quality evaluation of optical systems - Assessing the image quality degradation due to chromatic aberrations" defines terms, mathematical relationships and measurement guidance for assessing chromatic aberrations in optical and optoelectronic imaging systems. The standard applies to rotationally symmetric imaging geometry and covers both quasi‑monochromatic and finite spectral‑bandwidth measurements, providing a framework to quantify how dispersion (wavelength‑dependent refractive index) degrades image quality.
Key topics and requirements
- Terminology and symbols: Standardizes terms such as lateral and longitudinal chromatic aberration, image height, line spread function (LSF), edge spread function (ESF), point spread function (PSF), optical transfer function (OTF), modulation transfer function (MTF) and phase transfer function (PTF).
- Wavelength handling: Distinguishes quasi‑monochromatic measurements (single mean wavelength) from finite spectral bandwidth measurements using spectral weighting functions W(λ) and defines reference wavelength or reference spectral distribution.
- Measurement plane & image coordinates: Specifies how to define the measurement plane, image heights and local image field coordinates for consistent aberration evaluation.
- Lateral chromatic aberration (T(λ)): Defined as the radial displacement of image height at wavelength λ relative to a reference; includes weighted lateral chromatic aberration T(W) for spectral distributions.
- Longitudinal chromatic aberration (L(λ), L(W)): Relates to axial shifts of best‑focus position for different wavelengths or weighted spectra.
- Edge and line spread analysis: Uses ESF and LSF to quantify degradation in the space domain. Defines left edge width (LE), right edge width (RE) and combined edge width (EW) as image‑quality metrics linked to LSF and OTF/MTF.
- Measurement procedures and reporting: Provides general guidance for measurement methods, presentation of results, and test report contents; Annex A gives example result presentations.
Practical applications and users
ISO 15795:2002 is intended for professionals and organizations involved in optical image‑quality assessment, including:
- Lens and optical system designers (minimizing chromatic aberration)
- Camera and sensor manufacturers (evaluating optoelectronic imaging chains)
- Metrology and QA laboratories (standardized measurement and reporting)
- R&D teams in microscopy, machine vision, remote sensing and imaging product development
Using ISO 15795 helps ensure repeatable, comparable measurements of chromatic aberration effects, guiding design tradeoffs (lateral vs longitudinal correction), specifying tolerances, and validating system performance across wavelengths.
Related standards
Relevant cross‑references cited by ISO 15795:
- ISO 9334 - Optical transfer function (definitions & relationships)
- ISO 9335 - OTF measurement principles and procedures
- ISO 9039 - Determination of distortion
- ISO 11421 - Accuracy of OTF measurement
Keywords: ISO 15795:2002, chromatic aberrations, optics, optical instruments, image quality, lateral chromatic aberration, longitudinal chromatic aberration, ESF, LSF, OTF, MTF, optoelectronic imaging systems.