EN ISO 13468-1:2019

Overview

EN ISO 13468-1:2019 - Plastics - Determination of the total luminous transmittance of transparent materials - Part 1: Single-beam instrument - specifies a practical laboratory method to measure the total luminous transmittance (visible light transmission) of planar, substantially colourless plastics (films, sheets, mouldings). The method uses a single‑beam photometer with a specified CIE standard light source and photodetector and an integrating sphere to collect transmitted flux. It is intended for analytical testing and routine quality control. This standard is not applicable to plastics containing fluorescent materials and is normally used for specimens up to 10 mm thick.

Key topics and technical requirements

• Scope & limitations
  • Applies to transparent, substantially colourless plastics (includes faint tints).
  • Not for fluorescent plastics; specimens normally ≤ 10 mm (can be measured if instrument permits but results may not be comparable).
• Apparatus
  • Stabilized light source producing a parallel beam (ray angle ≤ 0.087 rad / 5°).
  • Integrating sphere with entrance, compensation and photodetector ports; total port area ≤ 3.0% of internal sphere area (150 mm diameter commonly used).
  • Photodetector output proportional to incident flux within ±1% over measurement range.
  • Internal sphere reflectance ≥ 90% and uniform within ±3%.
  • Light trap absorbing ≥ 95% of incident light.
  • Beam diameter 0.5–0.8× entrance port diameter; baffles to prevent direct light on detector.
• Performance & precision
  • Repeatability standard deviation ≤ 0.2%.
  • Within-laboratory reproducibility over long intervals not to exceed repeatability by more than a factor of 3.
• Specimen handling & mounting
  • Specimens free from defects, dust, scratches; held normal to the beam within ±2° and positioned close to sphere to capture scattered light.

Applications

• Routine quality control and acceptance testing of transparent plastics (packaging films, glazing sheets, optical components).
• Comparative performance evaluation of materials for light transmission (architectural, automotive, consumer products).
• Laboratory verification of product specifications where quick, precise luminous transmittance measurement is required.

Who should use this standard

• Materials/test engineers in plastics manufacturing
• Quality control and R&D laboratories
• Test laboratories offering optical property measurement services
• Product designers and specifiers requiring validated transmission data

Related standards

• ISO 13468-2 (double-beam spectrophotometer method)
• ISO 11664 series (Colorimetry / CIE standard observers & illuminants)
• ISO 291 (conditioning)
• ISO 5725 (accuracy, repeatability and reproducibility)
• CIE Publications No. 15 and No. 17

Keywords: EN ISO 13468-1:2019, total luminous transmittance, single-beam photometer, integrating sphere, transparent plastics, CIE standard illuminant D, quality control.