Image of the ARGOS interaction matrix showing the x- and y-direction slopes for each KL mode. Since the WFSs are SH, the image of the interaction matrix is the derivative of the wavefront in the x and y directions. The bottom line in the matrix displays the low-order modes: (from left to right) Tip, Tilt, Astigmatisms, Focus, and Coma. The inset shows 18 modes for illustration. Values are in arbitrary units, scaled from −1 to 1, while the interaction matrix used for the computation is in units of RMS wavefront deviation divided by unity slope [m arcsec⁻¹].