ALTANA Haze-Gard Dual - Manual (Page 44)

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English Specimen
Measurement Calibration
No compensation: different sphere efficiency
Specimen
Measurement Calibration
With compensation: same sphere efficiency
ASTM D 1003
Measurement conditions during calibration and actual measurement are
different. While part of the light that enters through the outlet escapes
calibration, during measurement the outlet with the specimen is closed.
Thus, the light in the sphere is increased by the proportion which is reflected
on the specimen.
ISO 13468
Measurement conditions during calibration and actual measurement are the
same. The specimen is placed at the compensation outlet during calibration
and during measurement it is placed at the measurement outlet. This means
that the sphere efficacy is completely dependent on the reflectance
properties of the specimen. The difference between the two measurement
methods can be up to 2% for clear glossy specimens.
11 Parameters