Spiral Spring Electrostatic Actuator For Double-Layer Deformable Mirror With Continuous Phase Sheet

A new electrostatic actuator for a double-layer deformable mirror (DM) with continuous phase sheet is presented. The electrostatic actuator employs an upper electrode consisting of multiple Archimedean spiral spring arms supporting a small mass central attachment point and is capable of separating the parameters of actuation voltage, spring constant, and resonance. The feature reduces the complexity in the designing of a double-layer DM with continuous phase sheet, which is widely employed in the adaptive optics area of astronomy. The fabricated device has a diameter of 1250 mu m with four single-crystal silicon spiral arms each having a length of 6030 mu m, thickness of 15 mu m, and width of 30 mu m. The actuator was simulated and tested to have a resonant frequency above 2600 Hz and was simulated to be capable of reaching similar to 5-mu m displacement with a drive voltage of <30 V with an actuator-electrode separation of 15 mu m, based on the performance parameter found experimentally. (C) 2019 Society of Photo-Optical Instrumentation Engineers (SPIE)