Maintenance of Retroreflectometers


The majority of instruments are used by publicly appointed and sworn experts, test institutions, authorities, marking companies or in quality management by industrial organisations. We recommend that the units be maintained every two years and the standards recalibrated in a photometrically accredited laboratory.

In order to ensure the long-term accuracy of DELTA measuring instruments, they must be handled with care and well looked after. As well as regular cleaning of the window in front of the lens and the calibration standards, the battery should also be used in accordance with the manufacturer’s instructions. Please contact us if you have any questions relating to care, maintenance and recalibration.

Every spring, we offer instrument maintenance at special rates. The standards can also be recalibrated as part of this work.

Recalibration of standards

DELTA has been accredited by DANAK and has the status of a national reference laboratory for testing and calibration in the fields of photometry, radiometry and colorimetry. The Danish accreditation body DANAK is a member of the EA (European Cooperation for Accreditation), which guarantees international recognition of the calibration certificates produced by the testing and calibration laboratory.

Every DELTA instrument is delivered from the factory with a calibration standard which has been verified in DELTA’s calibration laboratory for photometry. The origin of the standard and knowledge of the precise coefficients of luminous intensity form the basis for accurate and reproducible measurements. The calibration certificate guarantees that the standard has been calibrated in compliance with the quality criteria of the DELTA quality manual, which has been evaluated by DANAK.

The instrument standards can change their values over a period of time (e.g. due to UV radiation). For this reason, the standards should be recalibrated no later than every two years. A current calibration certificate is provided for each standard tested.

Cleaning of instrument and standard(s)
System check
Installation of software updates
Inspection of light sources
Inspection of batteries
Inspection illumination angle
Inspection observation angle
Inspection/adaption hardware
Inspection/adaption software
Calibration RL standard (replacement)optionaloptionaloptionaloptional
Conformity check Qd reference (replacement)optionaloptionaloptional
Stability test
System calibrationoptionaloptionaloptionaloptional
Inspection of printeroptionaloptional
Test interfaces
Inspection charger
Subject to technical changes. Special solutions for individual projects possible.

Important information:
In 01/2021 DELTA discontinued the production of the LTL-XL and LTL-X Mark II retroreflectometers. It is assumed that spare parts will still be available for 6 to 8 years (approx. 2027-2029).

DELTA ceased to provide spare parts and support for units of type LTL 2000/S/SQ, Qd30 and RetroSign 4000/4500 in June 2019.