sCMOS camera in SCExAO

Olivier Guyon, Christophe Clergeon

Neo sCMOS camera on the SCExAO optical bench.
[High resolution image - 5.0MB]

1. SCExAO Overview

The Subaru Coronagraphic Extreme-AO (SCExAO) system is a new instrument on the Subaru Telescope. It is designed to directly image planets around other stars and uses a range of newly developed high performance techniques to do so:

A coronagraph which optically removes the central starlight while keeping planet light, even if the planet to star separation is very small
An advanced high-performance wavefront control architecture, ensuring that the coronagraph can works at its designed performance level

2. sCMOS camera on SCExAO

The SCExAO system uses an sCMOS camera for high speed wavefront sensing in the visible. The current wavefront sensor is of the pyramid type, and the SCExAO team plans to upgrade it to a non-linear curvature wavefront sensor in the future. The sCMOS camera should be read with low latency, as fast as possible for this application. The latency should be equal or less than one frame (for example, latency <1ms between end of exposure and time at which the image is available in computer RAM for a loop running at 1kHz), and the loop speed should be as fast as possible, ideally faster than 1kHz. Since SCExAO is still under development, we can envision a lower speed at the beginning of the project (next few months), with increased speed when the system is performing routine science observations (in approximately 1 year).

3. Current status

We have installed the camera on our system, and we have performed on-sky observations with it, using the pyramid wavefront sensor. A full report of our last engineering night on sky can be found in this page .

4. Previous and ongoing contacts with Andor

Contacts : Alex Munson, Pariksheet Nanda, Barry Smith

Neo camera problems encountered and solved thanks to Andor Software Team:

Need of the new SDK3 for linux.
Need of the new Solis software for the Neo camera (windows).
Camera acquisition was slow and the video mode was not working with the Solis software. The firmware needed to be updated : release 2.0.
The new Firmware updated we had a segmentation fault acquiring data with the camera. Solution from Barry Smith : add the 'nopat' kernel to he boot loader configuration.

Problems still not solved:

AOILeft coordinate is not working on the SDK3. Andor has repeated the problem with AOILeft coordinate and is trying to find a solution (Barry Smith).
Speed of the camera acquisition is too slow to close the adaptive optics loop. Some delay in the buffer update is also observed. Andor said that the Neo camera needs a new firmware revision (3.0) to work faster (alex Munson). Should we send the camera to Andor for the new Firmware update? can we borrow a spare camera from Andor with the correct Firmware (3.0) to keep working on our project when Andor is updating our camera firmware?

Additional question:

Is it possible to receive a user's manual for the SDK3 with more details concerning the way to use the different camera parameters. The actual user manual introduced the different camera options but doesn't explain when and how we are supposed to use these options.