Uploaded July 2022 | Updated September 2026, 2 hours ago
The LISA telescope is a bidirectional component that is used to expand an outgoing laser beam to the far spacecraft as well as compress a small fraction of a large incoming beam to a diameter of a few mm at the optical bench. Since the telescope lies directly in the path of the long-baseline LISA interferometer, its structure must be dimensionally stable at the pm/√Hz level within the 0.1 mHz – 1 Hz frequency band. A way to measure the displacement noise along the optical path of the telescope is with a compact optical truss interferometer (OTI), consisting of three Fabry-Perot cavities mounted along the telescope to monitor structural distortions over time. The premise is that variations in the cavity lengths will be due to dimensional changes in the telescope structure along three different lateral positions. We have developed a fiber-coupled Pound-Drever-Hall (PDH) system that integrates a fiber injector, mode matching optics, and a cavity input mirror into a compact input stage. These input stages will be attached around the primary mirror of the telescope, while the cavity return mirrors will be attached around the secondary mirror of the telescope. Using a PDH-like frequency locking scheme, variations in the cavity lengths will shift the frequency of the locked 1064 nm light which can be monitored through a beat signal between the light from each cavity and a separate laser that is locked to an ultra-stable reference cavity. We have designed and procured three first-generation OTI cavities and are currently testing the prototypes to verify pm/√Hz displacement sensitivity. We will present details regarding the design, fabrication, and assembly of the OTI units as well as preliminary results on the prototype testing and plans for future testing and verification.
Authors: Kylan Jersey, Ian Harley-Trochimczyk, Yanqi Zhang, Felipe Guzman
Presenter: Kylan Jersey
The LISA telescope is a bidirectional component that is used to expand an outgoing laser beam to the far spacecraft as well as compress a small fraction of a large incoming beam to a diameter of a few mm at the optical bench. Since the telescope lies directly in the path of the long-baseline LISA interferometer, its structure must be dimensionally stable at the pm/√Hz level within the 0.1 mHz – 1 Hz frequency band. A way to measure the displacement noise along the optical path of the telescope is with a compact optical truss interferometer (OTI), consisting of three Fabry-Perot cavities mounted along the telescope to monitor structural distortions over time. The premise is that variations in the cavity lengths will be due to dimensional changes in the telescope structure along three different lateral positions. We have developed a fiber-coupled Pound-Drever-Hall (PDH) system that integrates a fiber injector, mode matching optics, and a cavity input mirror into a compact input stage. These input stages will be attached around the primary mirror of the telescope, while the cavity return mirrors will be attached around the secondary mirror of the telescope. Using a PDH-like frequency locking scheme, variations in the cavity lengths will shift the frequency of the locked 1064 nm light which can be monitored through a beat signal between the light from each cavity and a separate laser that is locked to an ultra-stable reference cavity. We have designed and procured three first-generation OTI cavities and are currently testing the prototypes to verify pm/√Hz displacement sensitivity. We will present details regarding the design, fabrication, and assembly of the OTI units as well as preliminary results on the prototype testing and plans for future testing and verification.
Authors: Kylan Jersey, Ian Harley-Trochimczyk, Yanqi Zhang, Felipe Guzman
Presenter: Kylan Jersey
