Optically remoted probe for sensing of RF in aerospace radars
The improvement of radar reliability may require the detection and monitoring of its handled power. For this purpose, a new sensor concept based on an optically remoted RF probe was investigated. This work presents such a dedicated photonic system. The optical probe allows dual-regime operations: testing both radar transmit and receive operations. This monitoring performs not only “Go - No Go” tests, but could also be used for calibration. The paper reports the preliminary demonstrations. A new optoelectronic transducer was realised and a mock-up of probe was assembled and tested.
Optically-remoted probes for airborne RF sensors
We detail new concepts of optically-remoted probes that can be applied to sense and calibrate RF systems used in airborne domain. The proposed sensors produce minimal perturbation on the probed electromagnetic fields since they are built from non-metallic material (expect for the tiny integrated antenna element). The inherent low sensitivity and cross-talk to electromagnetic waves of fibre-based transmissions allow the introduction of these probes in the vicinity of the radiating antennas. These approaches lead to significant improvements since they will enable the calibration of the full RF system (starting from its radiating elements up to the RF processing unit), while they can operate not only during integration phases but also during operations.
rPET detectors design and data processing
Small animal PET systems based on rotating planar detectors posses some interesting advantages for high sensitivity, high resolution imaging. We have designed the rPET detectors based on MLS crystals assembled on a 30times30 matrix optically coupled to a flat-panel PS-PMT. Weighted position readout circuits pre-process the 64 signals from the 8times8 anodes matrix, which are digitized using a charge-integrating converter. The amplification electronics, including the trigger output for coincidence detection, and the high voltage supply are integrated in a three PCBs stack that forms the base attached to the back of the PMT. The whole assembly is enclosed in a light tight, lead (Pb) shielded aluminum box. The detectors are mounted on a rotating gantry with more than 180 degrees rotation span. The digitized events are screened and histogramed, and a modified center of gravity algorithm removes from the position calculation those signals with poor signal to noise ratio. Apparent mean crystal size on the 511 keV field-flood images is 0.6 mm, mean peak-to-valley ratio is better than 8, and intrinsic resolution is 1.5 mm at the central row, with the energy window wide open. Sensitivity (CPS) for a pair of these detectors set in coincidence at 160 mm distance is 1%