XAOSIM: XAO-like system simulation environment

XAOSIM is a simulation package developed for theoretical and practical work in high angular resolution astronomy.

Why yet another XAO simulation environment?

The specificity of XAOSIM is that it was built around shared memory data structures defined in the context of the SCExAO instrument by Olivier Guyon and Frantz Martinache. This approach makes it possible to design real-time AO control software using XAOSIM’s simulation environment data and deploy it on an actual instrument (assuming that it uses the same exchange format) in a transparent manner.

In addition to the simulation library package, a shared memory data viewer GUI called shmview is now part of the distribution. Since using this tool is not required to use the other features of XAOSIM, the required additional libraries are not automatically installed. If you want to use this tool, you have to independently install:

pip install pyqt5
pip install qtppy
pip install pyqtgraph

shmview snapshot

Acknowledgement

The development and maintenance of XAOSIM receives support from the KERNEL project. KERNEL has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grand agreement CoG - 683029). For more information about the KERNEL project, visit: http://frantzmartinache.eu/index.php/category/kernel/

Recommandation for installation:

python setup.py install --user

This will create a .config/xaosim/ configuration directory in the user home folder.

It is also recommended to add ~/.local/bin/ to the path:

export PATH=$HOME/.local/bin/:$PATH

Documentation:

A documentation for XAOSIM is happening! Visit: http://frantzmartinache.eu/xaosim_doc/ for a tutorial that features some very pracrical uses of the package.

Example use:

The package makes it possible to simulate an extreme-AO “instrument”, that is a system made up of a telescope, an atmosphere, a deformable mirror that feed one or more cameras. To facilitate the use, it comes with a series of preset templates, such as the SCExAO instrument at the Subaru Telescope, the NIRC2 camera on Keck II, the NICMOS1 camera of HST, and a Shack-Hartman based AO system built at OCA for one of the C2PU telescopes. New templates can be added as required.

From within a python shell:

import xaosim as xs

scexao = xs.instrument("SCExAO", csz=245)
scexao.start()

Assuming that you’ve installed the libraries required to run the external shmview shared memory viewer:

shmview /dev/shm/maunakea.im.shm &
shmview /dev/shm/scexao_chuck.im.shm &

Will open two display utilities that show the live image and phase screen.

The package includes:

• a deformable mirror (DM) module that includes a multi-channel communication system, assumed to be located in a pupil plane. The DM class simulates a continuous membrane mirror with actuators laid out on a regualar grid.
• an atmospheric phase screen (Phscreen) module that simulates a Kolmogorov + Von Karman frozen screen drifting over the aperture in a predefined direction.
• a camera (Cam) module that produces images of a point source affected after the wavefront has undergone the transformation induced by the DM. One special case of camera is the Shack-Hartman camera (SHcam) used for wavefront sensing. Another special case is the coronagraphic camera (CoroCam) that can be used to simulate a wide range of coronagraphs (no PIAA-like coronagraphs though).

The code is reasonably well documented and if you are experienced with diffractive optics simulations, you should quickly feel at home, and change the parameters of the turbulence, simulate partial AO correction and even use a perfect coronagraph.

If you need more help, please check the dedicated documentation/tutorial webpage: http://frantzmartinache.eu/xaosim_doc/

Auxilliary tools:

• pupil: used to generate models of the aperture of several telescopes.
• zernike: used to generate Zernike wavefront modes on the DM.
• shmlib: a library that uses shared memory data structures like the ones designed to control the SCExAO instrument at the Subaru Telescope.
• shmview: a python GUI using the shared memory library to visualize the 2D data structures. The current version of shmview is no longer based on the pygame framework but on Qt5. This program benefits from an additional module designed by python guru Eric Jeschke (Subaru Telescope) to make it multi-thread safe.

Release Notes:

• March 2019: XAOSIM is now fully Python 3 compliant.
• May 2020: XAOSIM was rewritten during the COVID19 lockdown to accomodate emerging needs: segmented mirrors, higher fidelity DM simulation for fine focal plane-based metrology, Shack-Hartman camera, the ability to change the filter of the camera without altering the rest of the system.