Figure 8
The drift in the inverse radius of curvature of Mirror 3, as measured by a Fizeau interferometer, is independent of the power supply's voltage slew rate (80, 150 or 300 V s−1). This means that large (1000 V) voltage changes can be applied to a bimorph mirror in a matter of seconds without compromising the rate of the mirror's subsequent curvature drift. A logarithmic change in the mirror's curvature as a function of time further strengthens the argument that the remaining drift is due to piezo creep. |