85-electrode influence functions, E_i(r, θ). The influence functions (see Appendix A) correspond to the matrix C_h (see text). Panel a shows this as obtained from the calibration of the DM using sunlight on a pinhole located in front of the DM, and monitoring the measured pinhole positions from the 253-lenslet SH WFS, shown in Fig. 2, while the AO computer outputs a saw-tooth voltage on one electrode at the time. Panel b shows the same influence functions as calculated theoretically from the electrode layout and the thin-plate model (implemented as the solution to the Poisson equation, taking into account the three mounting points of the DM). The color-scaling in the upper panel is consistent with that in the lower panel.