The gravitational wave observatory and many other large ground-based instruments need to be decoupled from the Earth’s ever-present motion to improve their performance. In such scenarios, inertial sensors which measure the ground motion are necessary, especially those with a high resolution and a large dynamic range. This thesis aims to develop high performance inertial sensors which outperform the commercially available ones in terms of resolution and dynamic range in low frequency down to 0.01 Hz.Inertial sensors essentially consist of two parts: a single-degree-of-freedom mechanism and a transducer which converts mechanical quantities into electrical quantities. In this work, a novel interferometric readout based on homodyne quadrature interferometer is proposed and examined. Experimental results show that its resolution is 1e-11, 1e-12 and 2e-13 m/rtHz at 0.01, 0.1 and 1 Hz respectively. For the mechanical parts, the leaf spring pendulum and Lehman pendulum are used respectively as the restoring springs for the vertical and horizontal inertial sensors. With these, the resonance frequencies are made to 0.26 and 0.11 Hz, respectively. Combined with the interferometric readout, a Vertical Interferometric Inertial Sensor (VINS) and a Horizontal Interferometric Inertial Sensor (HINS) are developed. They are placed together in a vacuum chamber as an inertial unit to measure vertical and horizontal motion.A critical investigation of the developed HINS and VINS is performed. The passive VINS and HINS are compared, firstly, with a commercial seismometer (Guralp 6T) the results showed that they provide equivalent seismograms in frequencies from tides to 10 Hz. Secondly, both simulations and measurements have been conducted in this study, a noise budget of the interferometric readout itself was constructed, which corresponds to the case when the proof-mass of the inertial sensors is blocked. At present, the resolution of the interferometric readout is found to be limited by the photodetector noise from 0.01 to 1 Hz. Moreover, huddle tests were conducted for the inertial units to examine their overall performance. However, extra experiments and simulations are performed and it is found that the resolution identified from the experimental means is worse than that from the simulation. Nevertheless, the mismatch can be reduced by reducing the magnitude of input ground vibration, by reducing undesired inputs and improving the stability of the interferometric readout output signal. / Doctorat en Sciences de l'ingénieur et technologie / info:eu-repo/semantics/nonPublished

The BRIght Target Explorer (BRITE) constellation is revolutionary in the sense that the same scientific objectives can be achieved smaller (cm3 versus m3 ) and lighter (< 10kg versus 1, 000kg). It is a space astronomy mission, observing the variations in the apparent brightness of stars. The work presented herein focuses on the assembly, integration and test of the instrument used on-board six nanosatellites that form the constellation. The instrument is composed of an optical telescope equipped with a Charge Coupled Device (CCD) imager and a dedicated computer. This thesis provides a particular in-depth look into the inner workings of CCD. Methods used to characterize the instrument CCD in terms of its bias level stability, gain factor determination, saturation, dark current and readout noise level evaluation are provided. These methodologies are not limited to CCDs and they provide the basis for anyone who wishes to characterize any type of imager for scientic applications.

The BRIght Target Explorer (BRITE) constellation is revolutionary in the sense that the same scientific objectives can be achieved smaller (cm3 versus m3 ) and lighter (< 10kg versus 1, 000kg). It is a space astronomy mission, observing the variations in the apparent brightness of stars. The work presented herein focuses on the assembly, integration and test of the instrument used on-board six nanosatellites that form the constellation. The instrument is composed of an optical telescope equipped with a Charge Coupled Device (CCD) imager and a dedicated computer. This thesis provides a particular in-depth look into the inner workings of CCD. Methods used to characterize the instrument CCD in terms of its bias level stability, gain factor determination, saturation, dark current and readout noise level evaluation are provided. These methodologies are not limited to CCDs and they provide the basis for anyone who wishes to characterize any type of imager for scientic applications.