GKGM/GKGM-award

The Society for the Calibration of Geodetic Devices, “GKGM”, in German, engages in the advancement of research and science through fostering exchange and networking, initiating studies, disseminating information and contributing to the development of national and international standards. Its activities should benefit the geodetic community and society at large, but operators of geodetic calibration labs and users of geodetic devices in particular.

The Society established the GKGM-award in 2012 as a recognition of scientists who have contributed in an outstanding way to this field. There have been nine recipients, so far. At this year’s JISDM conference, Dr. Joffray Guillory will be distinguished for his substantial contributions to the development of multiwavelength EDM for traceability of distance measurements. His extensive track record includes the development of an instrument which automatically mitigates the dominant atmospheric effects, successful practical demonstration under field conditions at various sites, and a thorough uncertainty quantification.

Abstract of the celebratory speech

Arpent is an EDM that simultaneously measures two optical path lengths at two different wavelengths. As a result, this prototype instrument is able to measure distances without the necessity for the user to correct for the effects of air temperature or pressure. Indeed, the measured distances do not depend on the group refractive index of the air, but only on the dispersion. In addition, Arpent measures distances traceable to the SI definition of the metre, with an instrumental uncertainty of less than 1 mm at k=1 and a range of 8 km. In practice, this instrument has demonstrated that it can compensate for variations in the air refractive index when measuring a fixed distance. For example, it showed a standard deviation of 0.3 mm over several days at 2.6 km and 5.4 km. Moreover, when distance measurements of up to 6.5 km were compared with those of a GNSS-based distance metre, the discrepancies between the two systems had a standard deviation of only 1.8 mm.