TY - BOOK

T1 - Noise in the LISA phasemeter

AU - Bode, Christoph Heimo

PY - 2024

Y1 - 2024

N2 - The Laser Interferometer Space Antenna (LISA) is a satellite mission led by the European Space Agency (ESA), planned to be launched in 2035. It aims to detect gravitational waves (GWs) in the millihertz regime to reveal new insights about the universe. For this purpose, LISA will utilize heterodyne laser interferometry between free-falling test masses, with the GW signal inducing a tiny modulation on the optical beat note phase. Due to the tiny effect, this phase has to be extracted from the optical beat note with high precision. One fundamental part in the complex design of LISA is the phasemeter (PM), an instrument that receives the signal after it has been converted from the optical to the analog domain. The PM implements many functionalities and is essentially responsible for the actual phase extraction. Like all the subsystems in LISA, it must not introduce noise above certain established requirement levels. This thesis is about the analysis and measurement of different noise sources and limitations in the LISA PM. First, the digital part of the PM with respect to the phase readout, the so-called digital readout core (DRC), is analyzed in detail. The focus lies on the main readout algorithm, a phase-locked loop (PLL), and on the decimation filters needed for data rate reduction. The analysis includes a noise model of the complete DRC, which considers potential limitations like quantization noise, aliasing, and non-linear effects, among others. However, many noise sources in the PM are originating outside the digital domain. A critical part is the so-called back-end electronics (BEE) module, which contains all analog components critical for phase readout. Besides analog noise sources, environmental noise sources like thermal noise can couple into the system, with both potentially being interdependent. Further, noise originating from the input signal itself can spoil the phase readout performance. Fundamental and critical noise sources in these regards are discussed in the second part of this thesis. The experimental part of this thesis verifies and quantifies the noise models derived in the preceding sections. This includes a verification of the digital readout core models, as well as experiments to quantify potentially limiting effects in the PM. Further, it includes noise performance verification of critical components, readout algorithm alternatives, and an instrument for testing the PM. In the final part of this thesis, the noise performance of different PM core prototypes is analyzed, and compared to each other. This includes PM prototypes built with custom off-the-shelves hardware and prototypes built with space-compatible or equivalent parts. Some of the prototypes are tested in environmental conditions resembling the LISA case, i.e. in vacuum conditions.

AB - The Laser Interferometer Space Antenna (LISA) is a satellite mission led by the European Space Agency (ESA), planned to be launched in 2035. It aims to detect gravitational waves (GWs) in the millihertz regime to reveal new insights about the universe. For this purpose, LISA will utilize heterodyne laser interferometry between free-falling test masses, with the GW signal inducing a tiny modulation on the optical beat note phase. Due to the tiny effect, this phase has to be extracted from the optical beat note with high precision. One fundamental part in the complex design of LISA is the phasemeter (PM), an instrument that receives the signal after it has been converted from the optical to the analog domain. The PM implements many functionalities and is essentially responsible for the actual phase extraction. Like all the subsystems in LISA, it must not introduce noise above certain established requirement levels. This thesis is about the analysis and measurement of different noise sources and limitations in the LISA PM. First, the digital part of the PM with respect to the phase readout, the so-called digital readout core (DRC), is analyzed in detail. The focus lies on the main readout algorithm, a phase-locked loop (PLL), and on the decimation filters needed for data rate reduction. The analysis includes a noise model of the complete DRC, which considers potential limitations like quantization noise, aliasing, and non-linear effects, among others. However, many noise sources in the PM are originating outside the digital domain. A critical part is the so-called back-end electronics (BEE) module, which contains all analog components critical for phase readout. Besides analog noise sources, environmental noise sources like thermal noise can couple into the system, with both potentially being interdependent. Further, noise originating from the input signal itself can spoil the phase readout performance. Fundamental and critical noise sources in these regards are discussed in the second part of this thesis. The experimental part of this thesis verifies and quantifies the noise models derived in the preceding sections. This includes a verification of the digital readout core models, as well as experiments to quantify potentially limiting effects in the PM. Further, it includes noise performance verification of critical components, readout algorithm alternatives, and an instrument for testing the PM. In the final part of this thesis, the noise performance of different PM core prototypes is analyzed, and compared to each other. This includes PM prototypes built with custom off-the-shelves hardware and prototypes built with space-compatible or equivalent parts. Some of the prototypes are tested in environmental conditions resembling the LISA case, i.e. in vacuum conditions.

U2 - 10.15488/17997

DO - 10.15488/17997

M3 - Doctoral thesis

CY - Hannover

ER -