TFT TYPE 3 DIGITAL REFLECTOMETER
Overview
The TFT Digital Reflectometer is used to measure the whiteness of fabrics or materials. It measures the
percentage of light in the visible part of the spectrum reflected from the test surface. The readings are typically
used to identify trends in laundry effectiveness and to provide a quantitative measure that can be used as
acceptance criteria.
The reading does not include any contribution from ultraviolet or infra-red light.
TFT also make and supply a meter to measure the amount of Optical Brightening Agent (OBA) in a sample. The
OBA meter uses an ultraviolet light source which causes the material containing the OBA in the material to
fluoresce, giving off light in the blue part of the visible light spectrum. This visible light is measured by the meter
to give a reading of the amount of OBA in the material.
Contents
The Reflectometer is supplied in a padded plastic carry case which provides physical protection for the contents.
The carry case contains:
• Type 3 Digital Reflectometer
• Calibrated ceramic reference tile
• Mains-powered battery charger (which may also be used for a TFT OBA meter)
The calibration certificate is supplied separately in hard copy and/or as a pdf document.
Before first use
The meter screen is covered with a protective plastic film which can be peeled off.
The meter is supplied part-charged and is ready for use as received. If the red light is lit, the meter needs to be
charged – see below for instructions.
Sample preparation
The Reflectometer measures the amount of light reflected from the surface presented to the glass slide on the
base. Samples should be prepared that are large enough to cover the whole glass area at least.
Care needs to be taken to avoid the desk surface beneath the sample affecting the meter reading. A dark desk
surface could lead to a false low reading. Conversely, a light desk surface could lead to a false high reading.
To avoid this possibility, we recommend that material should be layered at least 4 layers thick. For more
transparent materials even more layers may be needed. The correct number of layers can be found
experimentally by adding layers and checking the reading each time until an extra layer does not significantly
change the meter reading.
The test sample should be as smooth and flat as possible in order to ensure consistency of the optical path
between the sample and the meter sensor. Any creases or folds in the sample will prevent the base of the
Reflectometer from sitting completely flat on the test sample creating shadow areas which will reduce the meter
reading.
TFT (Ilkley) Ltd.
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