(normative)
UV calibration service
B.1 General
In this part of ISO 2470, reference is made to special reference standards which are required to enable the
relative UV content in the illumination falling on the test piece to be adjusted to conform to the CIE illuminant C.
To enable this to be done, the following procedure is established.
B.2 Standardizing laboratories
A laboratory, or laboratories, equipped to make primary spectrofluorimetric measurements using the twomonochromator
method is appointed by ISO/TC 6 as “standardizing laboratory” in accordance with the
provisions of ISO 4094. This laboratory issues “ISO reference standards of level 2” (IR2) to the authorized
laboratories. Such reference standards shall be assigned spectral total radiance factor data for the
CIE illuminant C.
B.3 Authorized laboratories
B.3.1 Laboratories having the necessary technical competence and maintaining reference instruments
having the characteristics specified in ISO 2469 are appointed by ISO/TC 6 as “authorized laboratories” in
accordance with the provisions of ISO 4094.
NOTE It is anticipated that these authorized laboratories will be the same as those authorized in accordance with the
requirements of ISO 2469, but the standardizing laboratories will not necessarily be the same as those appointed
according to ISO 2469 since different equipment is required.
B.3.2 The authorized laboratory shall make necessary adjustments to correct for differences in the basic
photometric level between the instrument at the standardizing laboratory and the level specified for the
authorized laboratory in ISO 2469, before calculating the ISO-brightness value of the IR2 and using this value
to adjust the UV content of the reference instrument. The calculations shall be carried out using 10 nm data
and the weighting functions given in Annex A.
B.3.3 The authorized laboratory shall, if necessary, take steps to ensure that directional effects in the IR2
which may affect the measurements at the standardizing laboratory are recognized and taken into account
when determining the value to be used when transferring this calibration to an instrument providing a diffuse
illumination.
B.4 IR3 fluorescent reference standard
B.4.1 The fluorescent reference standard shall consist of white paper, uniform in radiance factor and aged
for a sufficient time to give the paper an optical stability of 4 to 6 months without a deterioration in the
ISO-brightness value of more than 0,1 %.
B.4.2 The standard shall be prepared in the form of opaque pads and shall have a smooth non-glossy
surface. The pad shall be covered with a suitable protective cover.
NOTE Fluorescent tablets and tiles are suitable local working standards but have been shown not to be suitable for
use as transfer standards for this procedure which is specific for white papers (Reference [4] in the Bibliography).
B.4.3 Since the interactive effect of the fluorescence emission into the integrating sphere creates a slight
non-linearity in the brightness scale, the IR2 and IR3 standards shall have an ISO-brightness value of
(95 ± 5) % and a fluorescence component of the ISO brightness of (10 ± 2) %.
B.5 Comments
This procedure is specific for white papers that may contain fluorescent whitening agents which emit light in
the blue portion of the visible spectrum (400 nm to 500 nm). This procedure does not provide a valid
adjustment for fluorescence in other spectral regions