Frank J. van Kann | Searcharxiv

arXiv2024

Project TAIPAN: Results from a Novel Gravity Gradiometer Field Test

Project TAIPAN has been carried out jointly by Trinity Research Lab and the Frequency and Quantum Metrology Research Group located at the School of Physics, Mathematics and Computing of the University of Western Australia (UWA). Lockheed Martin Corporation (USA) has also been a partner in this joint collaboration providing financial backing to the project and other support including advanced modelling, assessment of laboratory tests and data analysis. The project aim was to develop a miniaturised gravity gradiometer to measure horizontal mixed gradient components of the Earth gravity in a small, lightweight package that can be deployed in a fixed 4D mode, in a borehole, or on moving exploration platforms including ground-based, airborne and submersible. The gradiometer design has evolved through a few prototypes combining the design of its sensing element with ultra low noise microwave and capacitive read out. The most recent prototype of the gradiometer using novel ultra sensitive capacitive pick off metrology has been trialled in the harsh environment of Outback Western Australia over a known gravity anomaly displaying steep gradients. Despite adverse weather conditions, results of the trial indicate that the gradiometer operated as expected, closely replicating the gravity gradient profile extrapolated from a regional gravity survey.

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arXiv2023

A Novel Capacitance-to-Phase Transducer Based on a Simple Resonant Circuit

A novel room temperature capacitance-to-phase transducer is described, which uses a modified All-Pass filter architecture combined with a simple series resonant tank circuit with a moderate Q-factor. It is fashioned from a discrete inductor with small dissipation resonating with a grounded capacitor acting as the sensor, to obtain a relative resolution equal to or better than 10-11 in a 1 Hz bandwidth. The transducer converts the change in capacitance to the change in the phase of a carrier signal at the resonance frequency and is configured to act as a close approximation of the almost ideal All-Pass filter. This cancels out the effects of amplitude modulation when the carrier signal is imperfectly tuned to the resonance. When used as a mechanical displacement-to-phase transducer, the predicted position noise was approximately 3 femtometre/rootHz. Other applications of the proposed circuit include the measurement of the electric field, where the sensing capacitor depends on the applied electric field. In addition, the circuit can be easily adapted to function with very small capacitance values (1 - 2 pF) as is typical in MEMS-based transducers.

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