A 37-actuator polyimide deformable mirror with electrostatic actuation for adaptive optics microscopy

Widespread use of adaptive optics in life-science microscopy is predominantly hindered by the high cost of conventional MEMS deformable mirrors. We present here a potentially low-cost and compact alternative in the form of an electrostatic deformable mirror developed particularly for applications in adaptive optics microscopy. The device is fabricated with standard micro-machining processes using widely available materials to minimize cost, but still offers exceptional post-assembly mirror quality. With an aperture size of 10 mm, the device has a post-fabrication root-mean-square mirror flatness error of <250 nm and an active best-flat of <15 nm. The membrane is made of an aluminum-coated 3.5 m thick polyimide membrane that has high compliance, allowing a maximum peak-to-valley stroke of 15 m at 375 V. Driven using a custom-developed optimization-based open-loop control scheme, we successfully reproduced Zernike modes of up to fifth radial order with high shape fidelity.