What is the stroke of a deformable mirror?

There are two types of stroke defined for a deformable mirror — the maximum possible stroke and the maximum inter-actuator stroke. The former one characterises the maximum possible travel of a mirror surface when the maximum voltage is applied to all mirror actuators, the latter one describes the deformation when the maximum voltage is applied to a single actuator and zero voltage applied to all other actuators. The inter-actuator stroke is defined mainly by the actuator geometry and the membrane tension or the faceplate thickness. The maximum stroke for PDM is 6 μm at 300 V (or 8 μm at 400 V); for MMDM, it depends on the mirror size (about 9 μm for 15-mm mirrors and 18 µm for 50-mm mirrors).

For typical values of maximum and inter-actuator stroke of our mirrors, please refer to the Mirror Quick Guide.