Design Routine And Characterisation Of A Biconic Deformable Metal Mirror For Focus Shifting

This paper describes an opto-mechanical concept of a deformable metal mirror membrane, which can shift the focus position over a large range by use of a single actuator. The core element of the mirror is a diamond turned tulip-shaped membrane, the design is optimized to correct astigmatic aberrations which arise from the use of a curved mirror under a deflection angle. For this purpose, the target mirror surface is biconic. The manufactured mirror was tested with a maximum central deflection of 28 mu m and, when used in combination with a 200 mm focal lens, is capable of producing a focus shift of up to 17.9 mm with a resulting wavefront aberration of 238.7 nm RMSerror. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement