Research & Development

Research Topics

A pyramid prism splitting the beam into four pupil images

Super-sensitive wavefront sensing

We develop ideas on:

  • Super-sensitive wavefront sensors — we’re currently integrating a pyramid (modulated) in our lab
  • Non-linear wavefront sensing — give linearity away, reach out to new sensitivity realms
  • Spot-shrinkage for elongated laser-guide-star wavefront sensing on existing detectors

Publications

A point spread function with diffraction rings and its measured versus reconstructed radial profile

Post-processing AO-corrected telemetry / PSF reconstruction

Post-processing of partially corrected AO data for the reconstruction of the PSF is an extremely complex task, already in classical AO, let alone wide-field. We’re developing software classes to:

  • Reconstruct PSF out of tomographic MOAO systems
  • Provide Keck Observatory with a PSF reconstruction pipeline for the NGS and LGS modes
  • Pursue research leading to a working pipeline for the AOF’s MUSE instrument in wide and narrow field modes
  • Collaborate with NRC’s Herzberg Institute of Astrophysics in support of PSF reconstruction for LTAO systems (useful for our HARMONI project)
  • Collaborate with TMT PO on their effort to perform PSF reconstruction with MCAO systems

Publications

Guide stars probing turbulence layers above a telescope

Advanced tomography reconstruction methods

Turn-key AO requires robustness to operate 100% of the time at full performance. New processing architectures are needed to tackle the curse of dimensionality (scaling with the fourth power of the telescope diameter D⁴) while making efficient use of combined LGS and NGS measurements in any of the WFAO modes. We’re acquiring expertise and leading efforts in:

  • Fast wavefront reconstruction in the spatial-frequency domain
  • Multi-time-step tomographic reconstruction
  • Iterative, large-scale tomographic reconstruction
  • Kalman filters for large numbers of degrees-of-freedom architectures

Publications

Feedback loop with a controller and the residual power spectrum with a vibration peak suppressed

Advanced AO control

Optimal control squeezes the last nanometres out of an AO loop: it models the turbulence, the vibrations and the dynamics of the mirrors, and uses them to predict and correct. We work on:

  • Minimum-variance and LQG control, including deformable mirrors with their own dynamics and woofer–tweeter systems
  • Vibration identification and suppression for ELT-class systems and the VLTI
  • Wavefront control strategies for ELT instruments, such as stable DM fitting without modal truncation
  • Learning-based control, including reinforcement learning for extreme AO

Publications

Chain of OOMAO objects: source, atmosphere, telescope, wavefront sensor and deformable mirror

Modelling software development

We support the development of OOMAO, an object-oriented Matlab Adaptive Optics library. Objects from the different classes are assembled to perform the numerical modelling of adaptive-optics systems; OOMAO can be seen as an extension of the Matlab language, with overloaded operators used to propagate the wavefront through the system and update object properties.

It’s licence-free and free-of-charge. As a future user, you’re welcome to add to it and become an official co-developer — drop me an email.

Publications

Turbulence strength profile versus altitude with wind vectors per layer

Atmospheric parameter characterisation and identification

Atmospheric parameter identification is paramount for the runtime optimisation of tomography and the post-processing of AO telemetry.

Publications

A segmented pupil and its in-focus and defocused images

Phase-diversity for system calibration

As part of our running collaborations, we hosted Masen Lamb, PhD student at UVic, for 4 months (Mar–Jun 2016) to develop phase-diversity algorithms for AO systems calibration. These are now being applied to:

  • Fine co-phasing of segmented telescopes
  • Off-line calibration of non-common-path aberrations
  • Calibration of low-wind-effect

Publications

A star with its halo, a coronagraphic dark hole and a faint planet inside it

High-contrast imaging, extreme AO & exoplanets

Seeing a planet next to its star needs a very deep correction and a clean control of the residual halo. We contribute to the adaptive optics, the instrument concepts and the data analysis for:

  • Extreme AO and coronagraphy for the ELT Planetary Camera and Spectrograph (PCS)
  • The wind-driven halo and the low-wind effect in SPHERE and GRAVITY+
  • High-contrast imaging concepts and post-processing, from NFIRAOS/IRIS to speckle suppression
  • Exoplanet detection with radial-velocity spectrographs and with VLTI/GRAVITY+

Publications

A real-time computer between wavefront sensor and deformable mirror, streaming telemetry to a dashboard

Real-time computing & AO telemetry

An ELT-scale AO system has to compute thousands of actuator commands within a millisecond, and produces a flood of data that is valuable well beyond the loop itself. We work on:

  • Real-time computer design and performance modelling for ELT-scale AO, including GPU-based pipelines for METIS and the Keck RTC upgrade
  • A standard format for AO telemetry, to exchange and reuse data across observatories
  • Virtual access to telemetry and advanced visualisation tools

Publications

A deployable CubeSat telescope in orbit next to a neural network

Space optics & machine learning

The tools of adaptive optics carry over to space, and machine learning is starting to replace hand-made models where they fall short. We work on:

  • Deployable CubeSat telescopes for Earth observation and astronomy, and their phasing and error budgets
  • Space situational awareness with event-based (neuromorphic) sensors — see NEUROSPACEAWARE
  • Deep learning for phasing segmented telescopes and for wavefront sensing
  • Reinforcement learning for the control of extreme AO systems

Publications