Sensor noise in LISA Pathfinder: Laser frequency noise and its coupling to the optical test mass readout

Armano, M.; Audley, H.; Baird, J.; Binetruy, P.; Born, M.; Bortoluzzi, D.; Brandt, N.; Castelli, E.; Cavalleri, A.; Cesarini, A.; Cruise, A.  m.; Danzmann, K.; De Deus Silva, M.; Diepholz, I.; Dixon, G.; Dolesi, R.; Ferraioli, L.; Ferroni, V.; Fitzsimons, E.  d.; Flatscher, R.; Freschi, M.; García, A.; Gerndt, R.; Gesa, L.; Giardini, D.; Gibert, F.; Giusteri, R.; Grimani, C.; Grzymisch, J.; Guzman, F.; Harrison, I.; Hartig, M. -S.; Hechenblaikner, G.; Heinzel, G.; Hewitson, M.; Hollington, D.; Hoyland, D.; Hueller, M.; Inchauspé, H.; Jennrich, O.; Jetzer, P.; Johann, U.; Johlander, B.; Karnesis, N.; Kaune, B.; Killow, C.  j.; Korsakova, N.; Lobo, J.  a.; López-Zaragoza, J.  p.; Maarschalkerweerd, R.; Mance, D.; Martín, V.; Martin-Polo, L.; Martin-Porqueras, F.; Martino, J.; Mcnamara, P.  w.; Mendes, J.; Mendes, L.; Meshksar, N.; Monsky, A.; Nofrarias, M.; Paczkowski, S.; Perreur-Lloyd, M.; Petiteau, A.; Plagnol, E.; Ramos-Castro, J.; Reiche, J.; Rivas, F.; Robertson, D.  i.; Russano, G.; Sanjuan, J.; Slutsky, J.; Sopuerta, C.  f.; Steier, F.; Sumner, T.; Texier, D.; Thorpe, J.  i.; Vetrugno, D.; Vitale, S.; Wand, V.; Wanner, G.; Ward, H.; Wass, P.  j.; Weber, W.  j.; Wissel, L.; Wittchen, A.; Zweifel, P.

doi:10.1103/PhysRevD.109.042003

The LISA Pathfinder (LPF) mission successfully demonstrated the feasibility of the technology needed for the future space borne gravitational wave observatory LISA. A key subsystem under study was the laser interferometer, which measured the changes in relative distance in between two test masses (TMs). It achieved a sensitivity of 32.0-1.7+2.4 fm/Hz, which was significantly better than the prelaunch tests. This improved performance allowed direct observation of the influence of laser frequency noise in the readout. The differences in optical path lengths between the measurement and reference beams in the individual interferometers of our setup determined the level of this undesired readout noise. Here, we discuss the dedicated experiments performed on LPF to measure these differences with high precision. We reached differences in path length difference between (368±5) μm and (329.6±0.9) μm which are significantly below the required level of 1 mm or 1000 μm. These results are an import...

Sensor noise in LISA Pathfinder: Laser frequency noise and its coupling to the optical test mass readout / Armano, M.; Audley, H.; Baird, J.; Binetruy, P.; Born, M.; Bortoluzzi, D.; Brandt, N.; Castelli, E.; Cavalleri, A.; Cesarini, A.; Cruise, A. M.; Danzmann, K.; de Deus Silva, M.; Diepholz, I.; Dixon, G.; Dolesi, R.; Ferraioli, L.; Ferroni, V.; Fitzsimons, E. D.; Flatscher, R.; Freschi, M.; García, A.; Gerndt, R.; Gesa, L.; Giardini, D.; Gibert, F.; Giusteri, R.; Grimani, C.; Grzymisch, J.; Guzman, F.; Harrison, I.; Hartig, M. -S.; Hechenblaikner, G.; Heinzel, G.; Hewitson, M.; Hollington, D.; Hoyland, D.; Hueller, M.; Inchauspé, H.; Jennrich, O.; Jetzer, P.; Johann, U.; Johlander, B.; Karnesis, N.; Kaune, B.; Killow, C. J.; Korsakova, N.; Lobo, J. A.; López-Zaragoza, J. P.; Maarschalkerweerd, R.; Mance, D.; Martín, V.; Martin-Polo, L.; Martin-Porqueras, F.; Martino, J.; Mcnamara, P. W.; Mendes, J.; Mendes, L.; Meshksar, N.; Monsky, A.; Nofrarias, M.; Paczkowski, S.; Perreur-Lloyd, M.; Petiteau, A.; Plagnol, E.; Ramos-Castro, J.; Reiche, J.; Rivas, F.; Robertson, D. I.; Russano, G.; Sanjuan, J.; Slutsky, J.; Sopuerta, C. F.; Steier, F.; Sumner, T.; Texier, D.; Thorpe, J. I.; Vetrugno, D.; Vitale, S.; Wand, V.; Wanner, G.; Ward, H.; Wass, P. J.; Weber, W. J.; Wissel, L.; Wittchen, A.; Zweifel, P.. - In: PHYSICAL REVIEW D. - ISSN 2470-0010. - 109:4(2024). [10.1103/PhysRevD.109.042003]