Delta PG-35 Specifications download pdf (Page 40)

40 LTL-XL Retroreflectometer DELTA

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: 6 - Calibration normal

To make sure that calibration of the retroreflectometer is correct it is important that the ceram-

ics 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 repaired and recal-

ibrated. In case of dust on the ceramics surface of the reference, the use of compressed air is

recommended for removal. The use of a soft damp cloth is recommended if compressed air

fails to remove the dirt. If necessary, use a mild household detergent.

Service

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

recalibrated to a traceable standard. DELTA offers calibration traceable to PTB (Physikalsich-

Technische Bundesanstalt, Germany) and NIST (National Institute of Standards and Technol-

ogy, USA).

For information in service please contact your distributor or DELTA directly. At DELTA you

can forward your request via our web-site www.roadsensors.com or send a mail directly to:

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Delta PG-35 Specifications Page 40