ISO 20351-2024 PDF

Full title and description

Fine ceramics (advanced ceramics, advanced technical ceramics) — Test method for optical properties of ceramic phosphors for white light-emitting diodes using an integrating sphere. The document defines integrating-sphere‑based procedures to measure optical performance of ceramic phosphor powders used in white LEDs, including methods for internal and external quantum efficiency and absorptance measurements.

Abstract

This International Standard specifies test methods for using an integrating sphere to determine key optical properties of ceramic phosphor powders that are excited by UV or blue light and emit visible light for white LEDs. It includes an absolute method to measure internal quantum efficiency (IQE) and a substitution method to determine external quantum efficiency (EQE) and absorptance, the latter using reference materials whose EQE/absorptance are established (reference to ISO 23946 procedures). The standard updates and replaces the earlier 2017 edition with expanded, harmonized test procedures and reporting requirements.

General information

• Status: Published
• Publication date: 16 October 2024
• Publisher: International Organization for Standardization (ISO)
• ICS / categories: 81.060.30 (Advanced ceramics)
• Edition / version: Edition 2 (2024)
• Number of pages: 14 (ISO published text)

Scope

The standard applies to ceramic phosphor powders used in white light‑emitting diodes and specifies integrating‑sphere test procedures to measure optical properties (IQE, EQE, absorptance, spectral outputs). It covers absolute IQE measurement techniques and a substitution method for EQE and absorptance that uses calibrated reference materials; sample preparation, measurement geometry, sphere calibration, detector response corrections and uncertainty evaluation are addressed to ensure reproducible, comparable results across laboratories. This edition supersedes the 2017 edition and harmonizes integrating‑sphere methods with related ISO test procedures.

Key topics and requirements

• Integrating‑sphere measurement procedures for ceramic phosphor powders.
• Absolute method to determine internal quantum efficiency (IQE).
• Substitution method for external quantum efficiency (EQE) and absorptance using reference materials (reference values per ISO 23946).
• Requirements for sample presentation, lamp/excitation source, spectral calibration and detector correction.
• Sphere geometry, port configuration and stray‑light minimization practices.
• Data reduction, uncertainty estimation and required reporting elements to support interlaboratory comparability.

Typical use and users

Used by materials and optical test laboratories, LED and phosphor manufacturers, R&D groups in solid‑state lighting, quality and compliance testing organizations, and standards committees. The standard supports product characterization, supplier qualification, research on phosphor performance and interlaboratory comparisons for LED component qualification.

Related standards

Key related documents include the previous edition ISO 20351:2017 (withdrawn/replaced by this edition) and ISO 23946 (test methods and reference procedures used for EQE/absorptance reference materials and complementary optical measurement techniques). The standard is developed under ISO/TC 206 (Fine ceramics) and forms part of the ISO fine‑ceramics test method family for LED phosphors.

Keywords

ceramic phosphors; integrating sphere; internal quantum efficiency; external quantum efficiency; absorptance; LED phosphors; optical properties; ISO 20351; ISO 23946; fine ceramics; measurement uncertainty.

FAQ

Q: What is this standard?

A: ISO 20351:2024 is an ISO International Standard that specifies integrating‑sphere test methods for measuring optical properties of ceramic phosphor powders used in white LEDs, including IQE, EQE and absorptance.

Q: What does it cover?

A: It covers absolute IQE measurement, a substitution method for EQE and absorptance using reference materials, requirements for measurement geometry and instrumentation, calibration and correction procedures, uncertainty estimation and reporting content to ensure comparable results across laboratories.

Q: Who typically uses it?

A: Test laboratories, LED and phosphor manufacturers, research groups in solid‑state lighting, conformity assessment bodies and standards working groups who need standardized, reproducible methods for characterizing phosphor optical performance.

Q: Is it current or superseded?

A: ISO 20351:2024 is the current edition (published October 16, 2024) and supersedes ISO 20351:2017, which has been withdrawn and replaced by this 2024 edition.

Q: Is it part of a series?

A: Yes — it is part of ISO’s fine ceramics (advanced ceramics) test‑method family developed under ISO/TC 206 and is closely related to ISO 23946 and other optical test standards for ceramic phosphors and LED component characterization.

Q: What are the key keywords?

A: Ceramic phosphors, integrating sphere, IQE, EQE, absorptance, optical test methods, LED phosphors, measurement uncertainty, ISO 20351, ISO 23946.