S. Olivier¹ , N. Olivier² , A. Hue² , S. Le Mallet²

¹Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Direction des applications militaires (DAM), France
²Seismo Wave, Lannion, France

Abstract:

Usually, transducers implemented in infrasound sensors are composed mainly of two associated elements. The first converts the external pressure variation into a physical linear displacement. The second element converts this motion into an electrical signal. According to this configuration, MB3, MB2000 and MB2005 microbarometers use an aneroid capsule for the first element, and an electromagnetic transducer (Magnet-coil or LVDT) for the second one. Changing the electromagnetic transducer for an interferometer is a solution to increase the dynamic range and the resolution of the sensor. We are exploring this in order to propose a future optical microbarometer which will enlarge the range of infrasound sensors. First, we will present the new transducer principles, taking into account the aneroid capsule and the interferometer using integrated optics technology. Secondly, we will present the optical microbarometer in which the interferometer is positioned inside the aneroid capsule under vacuum. The adjustment of the interferometer position is a challenge we have solved. The optical measurement is naturally protected from environmental disturbances. Four prototypes were manufactured to compare their performance. Finally, we will present the results we obtained with this sensor (sensitivity, self-noise, effect of environmental disturbance, etc) compared to those of an MB3 microbarometer.