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Measurement and Optical Instrumentation

par LAROCHE Mathieu - publié le , mis à jour le

  • Contact : H. Gilles, S. Girard
  • PhD student : G. Lesueur
  • Projects and financial support : PEA-GRANDE (DGA)
  • Collaborations : Thales Air Systems, SupMeca


The theme « Optical Instrumentation and Measurements » has been meanly developed within the collaboration between the LIOA group and THALES Air System. This work was supported by DGA (Délégation Générale de l’Armement – France) in the framework of PEA – GRANDE project (GRandes ANtennes DEformables) (2011/09/29 to 2014/03/29). The project brought together THALES, the CIMAP Laboratory and Supmeca. THALES Group is manufacturing and marketing RADAR Antennas. The deployment of radar systems and their fabrication cost are directly proportional to the mechanical structure complexity supporting the radiating elements. Recent developments in radar front-end technology show a clear trend towards miniaturization and reduced weight. Therefore, a significant reduction of its rigidity will lead to potential gain in tactical deployment and cost savings. However, this would also conduct to significant degradations of their performances due to mechanical distortions resulting from external perturbations like wind, ice or thermal dilatation. One way for compensating these detrimental effects consists in acting directly on the amplitude and phase of the electronic signals sent on each individual radiating element to reshape the global radiation pattern. In this approach, the antenna is instrumented with transducers suitable for measuring in real-time the absolute distortions compared to a reference plane. The information provided by the sensors combined with mechanical models should allow recalculating the global mechanical shape of the structure and would maintain very good performances.

The LIOA team was in charge of developing optical sensors to track in real-time the deformations of the antenna. This work was initiated within the G. Lesueur’s thesis (2006-2009). The Deformable Antennas concept was approved and an optical solution was developed by our group. This preliminary work was valued by two publications and three patents.

The GRANDE (2011-2014) project was to experimentally demonstrate the Deformable Antennas concept. Optical solutions based on purely passive components appear to be very attractive for such applications. The approach uses passive optical probe made with fiber ribbons that intercept a laser light plane used as a reference plane. Each optical probe contains only passive optical components whereas all the optoelectronic and electronic parts of the sensor are delocalized under the emitting front side of the antenna via optical fiber links.

The LIOA group developed the optical sensor and provided the acquisition device and signal processing. Technology transfer has been completed and approved with the DGA thanks to an experiment on a real antenna. This experiment was performed on the site of Limours.

This work led to the publication of a book chapter (New Sensors and Processing Chain, Chapter 7 (2014), Ed. Wiley).