Development of methods for setting up a center for precision measurement and testing technology for optical measurement methods (POV)

Interferometer track with operator station (left) and sensors i3mainz, CC BY SA 4.0

For several years, i3mainz, in cooperation with industrial partners, has been further developing the measuring system for high-precision length determination, the length comparator “LK5”, and optimizing it for photogrammetric measuring tasks. The measuring system has been specially designed by i3mainz to calibrate photogrammetric precision scales of up to 2.3 meters with circular target marks. The measurement sections should be able to be determined with an accuracy of ±5 μm.


Since the need of companies to calibrate photogrammetric scales is increasing, DAkkS accreditation (DAkkS: German Accreditation Body GmbH) as a testing and calibration laboratory is being sought soon. With accreditation as a calibration laboratory, i3mainz should be able to issue DAkkS calibration certificates in the future. This is intended to create another part for setting up a test center for optical measurement methods.


In order to ensure maximum stability in terms of rod holder during the measurement process, the concept of the modular rod holder intended by i3mainz was implemented. The bracket (manufactured by Kotter m+o Engineering e. K.) consists of a rail that is attached to the carriage. Depending on the shape of the rod, modular guides can be attached to the rail, into which the rod is placed. In addition, the rod is fixed from above with another piece adapted to the rod by screwing it to the lower guide. Due to the modular structure, scales of different shapes (round, trapezoidal, etc.) and sizes can be accommodated. Test measurements by the i3 project group prove that the structure described ensures stable and tension-free mounting of the rod. After the implementation, further measurements followed to check the functionality of the LK5 control and evaluation software and to optimize the measurement process.

Furthermore, the i3mainz carried out investigations and test measurements on the stability of the room air conditioning. Although the room climate is monitored by temperature, air pressure and humidity sensors at two climate stations and is mathematically compensated for when measuring or calculating the length of the ruler, sudden changes in the external conditions are undesirable. Because short-term changes in the room climate are difficult to compensate due to the inertia of the sensors, the measuring system and the rod to be measured. As test measurements have shown, there are no sudden, significant changes in the room climate. The room climate remains almost stable.

A remaining task is the conception of a suitable software solution for order processing, which supports the workflow for a calibration order from the first contact with the customer to the handing over of the calibration certificate to the invoicing.