Update on development of WFS cameras at ESO for the ELT

The success of the next generation of instruments for 20m plus class optical telescopes will depend upon improving the image quality by exploiting sophisticated Adaptive Optics (AO) systems. For several years now, ESO has been very active in gathering requirements, planning, and developing detectors and controllers/cameras for the AO systems of the telescope and instruments of the ELT. From these requirements, the need for three different types of cameras have been identified: 1) ALICE (smALl vIsible CamEra) for Truth/High Order Natural Guide Star (NGS)/Telescope Guiding which uses the “sub-electron RON” Teledyne-e2v CCD220-DD of 240x240 of 24μm pixels; 2) LISA (Large vISble cAmera) for Shack-Hartmann Laser Guide Star (LGS)/Telescope Wavefront Sensing (WFS) which uses the Teledyne-e2v LVSM of 800x800 of 24μm pixels; 3) SAPHIRA Standalone Camera for Low-/High-Order NGS WFS/Fine Centering which uses the Leonardo SAPHIRA of 320x256 of 24μm pixels. This paper provides an update on the development of these cameras and their detectors. For ALICE and LISA, a single camera design approach is being followed with the only difference being the customizable front-ends to support the different type of detector. ALICE and LISA are being built around a common set of components and will look essentially identical from the exterior. COTS modules are being used wherever possible and practical to reduce the development effort and time, and improve functionality and maintainability. A description of the design approach, the common components and the detector specific front-ends will be presented. The LISA camera detector, the LVSM, is under development by Teledyne-e2v. A brief update on the progress of this development will be provided. For the SAPHIRA standalone camera, a different approach is being followed to that of ALICE and LISA. C-RED ONE cameras are being procured from FLI and will be modified by ESO to comply with ELT standards: 10GbE interfaces to the Real Time Computer (RTC) and NGC control computer, and Precision Time Protocol (PTP). PTP is the time reference system of the ELT and will be used by the cameras to schedule and time stamp frames and for synchronizing with other cameras or hardware devices.