Durham adaptive optics real-time controller

Abstract

The Durham adaptive optics (AO) real-time controller was initially a proof of concept design for a generic AO control system. It has since been developed into a modern and powerful central-processing-unit-based real-time control system, capable of using hardware acceleration (including field programmable gate arrays and graphical processing units), based primarily around commercial off-the-shelf hardware. It is powerful enough to be used as the real-time controller for all currently planned 8 m class telescope AO systems. Here we give details of this controller and the concepts behind it, and report on performance, including latency and jitter, which is less than 10 μs for small AO systems.

Analysis of on-sky MOAO performance of CANARY using natural guide stars

“…The real-time computer (RTC), called DARC (Durham Adaptive optics Real time Controller) is described in Dipper et al (2010) and Basden et al (2010). The system is driven at a selectable sampling frequency of up to 250 Hz, limited by the WFS camera readout rate.…”

MOAO first on-sky demonstration with CANARY

“…The real-time computer (RTC) architecture is described in Dipper et al (2010) and Basden et al (2010). The system is driven at a selectable sampling frequency of up to 250 Hz, which is limited by the WFS readout speed.…”

Investigation of POWER8 processors for astronomical adaptive optics real-time control

“…The DARC RTCS uses a horizontal processing strategy (Basden et al 2010) with each thread operating on WFS data from start to finish, rather than having different threads performing individual tasks (e.g. a set of threads for image calibration, a set for slope computation, and a set for wavefront reconstruction).…”

“…In recent years, there has been much success with hardware agnostic AO RTCSs which operate on conventional PC hardware, including the Durham AO real-time controller (DARC) (Basden et al 2010;Basden & Myers 2012), which is a generic system, used by the CANARY AO on-sky demonstrator instrument (Myers et al 2008), and the realtime control system for the Gemini South telescope GeMS AO system (Rigaut et al 2012). In theory, such systems simply require a recompilation of the source code to be ported to other (similar) hardware platforms, and are easy to move onto upgraded hardware.…”

“…Although porting to new hardware is typically limited to other PC-like systems that have an operating system running on a central processing unit (CPU), this is not always the case. In particular, the DARC system has a modular design which allows parts of the real-time pipeline to be placed in alternative hardware, including for example: (i) pixel processing and slope calculation in FPGA using a customised version of the SPARTA system (Fedrigo et al 2006) (ii) wavefront reconstruction using graphics processing units (GPUs) (Basden et al 2010) (iii) a full GPU pipeline, from raw WFS images to DM demands.…”