Spatial light modulator on Santa Cruz Extreme AO Laboratory (SEAL) testbed

The Santa cruz Extreme Adaptive optics (AO) laboratory (SEAL) testbed is designed to develop and prototype new technologies for high contrast imaging systems aimed at directly imaging exoplanets. SEAL consists of three deformable mirrors (DMs; segmented IrisAO, low-order ALPAO, and high order MEMS DMs), four pupil plane wavefront sensors (Shack-Hartman, two different Pyramid, and Zernike wavefront sensors), the FAST focal plane wavefront sensor, a suite of coronagraphs, and a CACAO based real-time-computer (RTC). Intending to test new AO control algorithms as well as compare new techniques with SEAL before implementing on-sky, we want to inject realistic atmospheric turbulence and study the effects of uncorrected high-order spatial modes in our system (e.g., the effects of aliasing and frequency folding on predictive control). To mimic continuous turbulence, as seen on-sky, we use a custom Meadowlark spatial light modulator (SLM). With a maximum stroke of 6pi (1.9um at 633 nm) and 1152x1920 pixels, we can simulate single layer turbulence with r0 of 11 cm and as well as reproduce the nominal conditions of r0>20cm on Mauna Kea. In this paper, we present the first results using our SLM to generate turbulence. We characterize the performance of the SLM by studying its spatial and temporal responses. We then show results with the different configurations SEAL enables with turbulence we inject using the SLM. We also provide practical information on the Python interface with SLM.