Speaker
Description
Direct imaging of exoplanets using ground-based telescopes requires coronagraphs operating at deep contrast together with precise wavefront control. While state-of-the-art extreme adaptive optic systems remove the majority of wavefront aberrations caused by atmospheric turbulence, residual errors remain causing leakage of starlight and decreasing the coronagraphic performance. Additional aberrations introduced by telescope vibrations and evolving non-common path aberrations (NCPA) further degrade contrast. Some of these errors can be sensed using a low-order wavefront sensor that measures reflected starlight from a reflective focal plane mask or Lyot stop, driving a control loop on a dedicated deformable mirror.
In this presentation, I discuss the development of a fully physics-based, differentiable "digital twin" of the focal plane low-order wavefront sensor (FLOWFS) system on the MagAO-X instrument. This model provides accurate forward modelling of wavefront aberrations, allowing us to reconstruct the wavefront errors introduced before or after the reflective focal plane mask using non-linear optimisation. A small calibration set of lab data is used to fit the model to the instrument, after which it is used to derive a linear interaction matrix to correct for low-order correction at 8kHz. During observation, the model can be updated using non-linear optimisation without disrupting the observation and low-order control loop.
Because the digital twin is fully physics-based, it is robust to changing observing conditions and can be easily adapted to different coronagraph configurations or filters with minimal recalibration. I will present on-sky results demonstrating improved low-order stability and enhanced coronagraphic performance from this approach, now integrated into the MagAO-X system. These methods are broadly applicable to other extreme AO platforms and provide a pathway to the robust wavefront control that will be essential for extremely large telescopes.
| Talk category | Splinter 1: Large Infrastructure and instrumentation |
|---|---|
| Second preference | Instrumentation for direct imaging of exoplanets, so whatever fits that |
