Delta LTL2000S - Manual (Page 19)

DELTA LTL2000S(Q) Retroreflectometer 15
Figure 6: The LTL2000S(Q) illuminations/measurement fields ( 5mm profile capabil-
ity) compared to a system with identical fields (< 0.5 mm profile capability) clearly
shows the advantage of the LTL2000S(Q) for obtaining reliable and reproducible meas-
urements on real markings.
Qd Measurement
The Qd part of the LTL2000SQ Retroreflectometer measures the Qd (coefficient of diffuse
reflected luminance) parameter. The Qd parameter represents the Lightness of road surfaces
and road markings seen by drivers of motor vehicles under daylight conditions or with sta-
tionary lighting.
The Qd measurement function of the LTL2000SQ complies with the EN1436 for normal non-
glossy road markings with a maximum profile. For measurement on glossy road markings or
markings with a profile height exceeding 2 mm please contact DELTA.
The illumination system recommended in EN1436 for obtaining the diffuse illumination for
measuring of Qd is an integrating sphere but it is also stated that other illuminations systems
can be used if similar results are obtained. The very compact illumination systems in
LTL2000SQ is a result of a considerable research effort at DELTA using advanced optical
simulation programs. The patent pending illumination system is shown in figure 7. The re-
sults obtained with this illumination system is in close agreement with results obtained on Qd
measurements using an integrating sphere systems as Qd30 for normal non-glossy road
markings with a profile height up to 2 mm. For further information regarding this matter
please contact DELTA.
Before tilt /shift of high position
After tilt/shift of high position
Area not measured
LTL2000
Competitor
LTL2000
Competitor
5 mm profile capability.
< 0.5 mm profile capabilty
5 mm profile capability.
< 0.5 mm profile capabilty