Delta PG-40 Specifications download pdf (Page 44)

44 LTL-X Retrometer DELTA

The reference

Zero Signal

Calibration unit

Reference

The road marking is simulated by a piece of white ceramic (the reference) mounted on an

aluminum profile. Ceramics have very stable optical properties because of the smooth surface.

Figure: 5 - Calibration normal

To make sure that calibration of the retrometer is correct it is important that the ceramics and

light trap on the calibration unit is clean and undamaged. Always keep the calibration unit

well protected.

If the ceramic is stained, scratched or broken, the calibration unit has to be replaced and cali-

brated. In case of dust on the ceramics surface of the traceable reference, the use of com-

pressed air is recommended for removal. To clean the ceramic reference on the field calibra-

tion unit, the use of a soft damp cloth is recommended if compressed air fails to remove the

dirt. If necessary, use a mild household detergent. A calibration transfer must always be com-

pleted after the field reference is cleaned. It is necessary to have the traceable reference avail-

able to perform the transfer prior to cleaning the field reference.

To ensure reliable measurements, it is recommended that the calibration unit be periodically

recalibrated to a traceable standard. DELTA Light & Optics offers calibration traceable to

PTB (Physikalsich-Technishe Bundesanstalt). For information contact your distributor or

DELTA.

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Delta PG-40 Specifications Page 44