Characterization of an off-the-shelf detector for high-order wavefront sensing in solar adaptive optics

When completed, the Advanced Technology Solar Telescope (ATST) will be the largest and most technologically advanced solar telescope in the world. As such, it faces many challenges that have not previously been solved. One of these challenges is the high-order wavefront sensor (HOWFS) for the ATST adaptive optics system. The HOWFS requires a 960 x 960 detector array that must run at a 2 kHz frame rate in order for the adaptive optics to achieve its required bandwidth. This detector must be able to accurately image low-contrast solar granulation in order to provide usable wavefront information. We have identified the Vision Research DS-440 as an off-the-shelf solution for the HOWFS detector and demonstrate tests proving that the camera will be able to lock the adaptive optics loop on solar granulation in commonly-experienced daytime seeing conditions. Tests presented quantify the noise, linearity, gain, stability, and well depth of the camera. Laboratory tests with artificial targets demonstrate its ability to accurately track low-contrast objects and on-sky demonstrations showcase the camera's performance in realistic observing conditions.