A new CCD-based technique for the calibration of leveling rods
Wasmeier, Peter and Karl Foppe
At the Geodetic Laboratory at the Technical University Munich (TUM) there are the most advanced calibrators for precise leveling invar rods. They are equipped with a laser interferometer as a reference, and with an CCD array camera to detect the bars on the rod scales. The technical setup, which was initially developed at the Chair of Geodesy at the TUM and is now state-of-the-art, is explained in this article. Further on, the concept of image acquisition and detection of graduation bar edges is shown. Due to the wide field of view nearly the whole graduation width can be observed. The scale of the graduation therefore can be measured for different areas in only one working step, so differences or inhomogeneities of the scale due to manufacturing tracks can be identified very quickly and easily. The influence of rod scale variations with respect to other measurement influences is shown. Furthermore, additional photographic information from the measurement system can be used e.g. to measure the graduation bar slopes or for documentation purposes. The calibrators can not only be used for leveling rods, but also for various other objects like subtense bars.
Event: XXIII International FIG Congress : Shaping the change
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