ISO 10820:2025

International
Standard
ISO 10820
First edition
Fine ceramics (advanced ceramics,
2025-09
advanced technical ceramics) —
Ultraviolet irradiation equipment
using UV-A LEDs and optical
radiometry for performance test
of semiconducting photocatalytic
materials
Reference number
© ISO 2025
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Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Irradiation equipment . 3
4.1 UV-LED Chip properties .3
4.2 UV-LED irradiation equipment .4
4.3 UV-LED Chip replacement .4
5 UV radiometers and spectroradiometers . 4
5.1 General .4
5.2 UV radiometers .4
5.3 Spectroradiometers .4
6 Report of irradiation equipment in each application standard . 5
Annex A (informative) Irradiation equipment having multiple UV-LED chips . 6
Bibliography .11

iii
Foreword
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This document was prepared by Technical Committee ISO/TC 206, Fine Ceramics.
Any feedback or questions on this document should be directed to the user’s national standards body. A
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iv
Introduction
Photocatalytic materials are useful in the treatment of harmful environmental pollutants and
microorganisms. The market has been expanding significantly over the past 20 years, with the development
[1]
of test methods for various functions of photocatalyst, including ISO 27447 . Light irradiation equipment
[2]
is indispensable for testing photocatalytic materials, and ISO 10677 is widely used as a common UV light
source standard in various ISO performance test methods.
In recent years, LEDs that are highly efficient and do not use harmful substances such as mercury have
been rapidly developed even in the UV range, and conventional fluorescent lighting will be more difficult to
provision in the future. Since the characteristics of LEDs are significantly different from those of conventional
UV light sources, this document has been developed so that UV-LEDs can be used for performance testing of
various photocatalytic materials. UV-LEDs with a peak wavelength of 365 nm are chosen because they are
commonly available and good for photoexcitation of most of semiconductor photocatalysts.
Currently, no other ISO standard exists that uses UV-LED as the test light source for photocatalytic materials.
[2]
ISO 10677 will continue to be maintained for the time being for conventional light source users.

v
International Standard ISO 10820:2025(en)
Fine ceramics (advanced ceramics, advanced technical
ceramics) — Ultraviolet irradiation equipment using
UV-A LEDs and optical radiometry for performance test of
semiconducting photocatalytic materials
1 Scope
This document specifies the irradiation equipment using ultraviolet light emitting diode (UV-LED) and
optical radiometry for testing the performance of semiconducting photocatalytic materials. The UV-LED
irradiation equipment specified in this document uses UV-LEDs having a peak wavelength of 365 nm in
the UV-A range and applies for a semiconductor photocatalyst exhibiting a photocatalytic function at this
wavelength.
[2]
This document applies only to irradiation equipment using UV-LED. ISO 10677 is applicable for equipment
using conventional UV light sources such as fluorescent lamps.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
bandwidth
Δλ
measure of the width of a bandpass function defined by:
∫−b()λλ dλ
Δλ =
b λ
()
where
b(λ - λ ) is the bandpass function about the central wavelength, λ ;
0 0
b(λ ) is the bandpass function at the central wavelength, λ .
0 0
Note 1 to entry: In geometric terms, the bandwidth is the width of a rectangle with the same area as the bandpass
function and height the same as the bandpass function at the nominal centre wavelength, λ .
Note 2 to entry: For a triangular or trapezoid bandpass, the bandwidth is equal to the full width at half maximum (FWHM).
[5]
[SOURCE: CIE 233:2019, 3.3 ]
3.2
cut-off wavelength
wavelength for which spectral distribution of UV-LED is 5 %
Note 1 to entry: See Figure 1, Key D.
[8]
[SOURCE: CEN/TS 16599:2014, 3 ]
Key
X wavelength, nm
Y relative spectral irradiance
A maximum wavelength, nm
B full-width at half maximum (FWHM), nm
C cut-on wavelength, nm
D cut-off wavelength, nm
Figure 1 — Definitions of spectral characteristics of UV-LEDs
3.3
cut-on wavelength
wavelength for which spectral distribution of UV-LED is 2 %
Note 1 to entry: See Figure 1, Key C.
[8]
[SOURCE: CEN TS 16599:2014, 3 ]
3.4
directional response index (cosine response index) for irradiance
f
index describing the responsivity of the photometer to light incident at an angle other than normal (the
cosine law for general purpose illuminance meters)
[3]
[SOURCE: ISO/CIE 19476:2014, 3.2.5 ]
3.5
full-width at half maximum
FWHM
wavelength difference between the half-maximum points of the bandpass
Note 1 to entry: See Figure 1, Key B.
[5]
[SOURCE: CIE 233:2019, 3.4 ]
3.6
irradiation equipment
equipment for irradiation having a light source or multiple light sources
3.7
photocatalyst
substance that performs one or more catalytic functions based on oxidation or reduction reactions under
photoirradiation
Note 1 to entry: The functions include decomposition and removal of air and water contaminants, deodorization,
antibacterial, self-cleaning, and antifogging actions. A photocatalyst can also be used for light energy conversion.
3.8
spectral responsivity
s(λ)
quotient of the detector output, dY(λ), by the monochromatic detector input, dX (λ)=X (λ)dλ, in the
e e,λ
wavelength interval, dλ, as a function of wavelength, λ
dY()λ
s λ =
()
dX ()λ
e
[4]
Note 1 to entry: This entry was numbered 845-05-56 in IEC 60050-845:2020 .
[4]
[SOURCE: IEC 60050-845:2020, 845-25-063 ]
3.9
spectroradiometer
instrument for measuring radiometric quantities in narrow wavelength intervals over a given spectral region
[4]
[SOURCE: IEC 60050-845:2020, 845-25-007 ]
3.10
ultraviolet light emitting diode
UV-LED
solid state device embodying a p-n junction, emitting incoherent ultraviolet radiation when excited by an
electric current
3.11
UV radiometer
instrument for measuring the total (spectrally-weighted and integrated) radiation, either irradiance or dose
(radiant exposure, time-integrated) over a limited spectral band in the ultraviolet region from an artificial
source of optical radiation
Note 1 to entry: A UV radiometer may be used to measure radiation from a broadband UV source, such as a high-
pressure mercury (Hg) arc lamp or a xenon (Xe) arc lamp, or from a line source such as a low-pressure Hg arc lamp,
whose spectrum is concentrated essentially in a single wavelength at about 365 nm, or from UV light emitting diodes
(UV-LEDs).
[6]
[SOURCE: CIE 220:2016, 2.2 ]
4 Irradiation equipment
4.1 UV-LED Chip properties
a) A peak wavelength of optical radiation shall be 365 nm ± 5 nm.
b) A full width at half maximum (FWHM) of UV radiation shall be ≤ 10 nm.
c) A cut-on wavelength should be 345 nm ± 5 nm.
d) A cut-off wavelength should be 385 nm ± 5 nm.

[8]
Definitions of spectral characteristics of UV-LED chips are shown in Figure 1.
4.2 UV-LED irradiation equipment
a) UV-LED chips shall be driven by direct current (DC). Alternating current (AC) driven LEDs shall not be used.
b) The uniformity of the irradiation surface is defined as U = abs(E - E )/E x 100 (in %), where E and
av min av av
E are the average and minimum UV irradiance on the sample surface, respectively.
min
c) When multiple UV-LED chips are used for getting a large uniform irradiation surface or for combination
of multiple irradiation units for an irradiation equipment, at least, the same UV-LED chips (same
manufacturer and same catalogue number) shall be used. A selection of UV-LED chip by a maximum
wavelength of radiation is strongly recommended. An example of irradiation equipment having multiple
UV-LED chips is shown in Annex A for information.
d) The UV irradiance shall be measured at start, end and each 1-h interval of the irradiation to
photocatalytic material under the condition in each testing standard. Then the stability of UV irradiance
shall be ≤ 1,2
...