Simulative and Experimental Characterization of an Adaptive Astigmatic Membrane Mirror

Abstract

Adaptive optical (AO) components play an important role in numerous optical applications, from astronomical telescopes to microscope imaging systems. For most of these AO components, the induced wavefront correction, respectively added optical power, is based on a rotationally symmetric or segmented design of the AO component. In this work, we report on the design, fabrication, and characterization of a micro-electronic-mechanical system (MEMS) adaptive membrane mirror in the shape of a parabolic cylinder. In order to interpret the experimental characterization results correctly and provide a tool for future application development, this is accompanied by the setup of an optical simulation model. The characterization results showed a parabolically deformable membrane mirror with an aperture of 8 × 2 mm2 and an adaptive range for the optical power from 0.3 to 6.1 m−1 (dpt). The optical simulation model, using the Gaussian beamlet propagation method, was successfully validated by laser beam profile measurements taken in the optical characterization setup. This MEMS-based adaptive astigmatic membrane mirror, together with the accompanying simulation model, could be a key component for the rapid development of new optical systems, e.g., adaptive laser line generators.

Technologies and applications of silicon-based micro-optical electromechanical systems: A brief review

“…(e) An electrothermal bimorph-actuated MOEMS mirror [41] . (f) A 3D curved micromirror for collimating the output beam of single-mode fibers [42] . (g) Cross section and top view of an electromechanically driven adaptive astigmatic membrane mirror [43] .…”

“…The in-plane optical beam collimation is an important performance factor in optical MEMS. It is usually achieved by integrating microlenses in the system [42] , which greatly limits the working wavelength range of the system and increases the manufacturing and assembly cost. In 2017, Sabry et al demonstrated optical fiber light collimation using a Si MEMS 3D curved mirror, as shown in Fig.…”

“…In 2017, Sabry et al demonstrated optical fiber light collimation using a Si MEMS 3D curved mirror, as shown in Fig. 2(f) [42] . When the incident beam is in-plane and inclined at 45° with respect to the principal axis, the reflected beam shows a beamwaist ratio of ~4.25 and an ~12 dB reduction in propagation losses [42] .…”

“…2(f) [42] . When the incident beam is in-plane and inclined at 45° with respect to the principal axis, the reflected beam shows a beamwaist ratio of ~4.25 and an ~12 dB reduction in propagation losses [42] . This type of micromirror may potentially replace lensed fibers that are widely used in MOEMS to produce monolithically integrated systems, achieving wider-band spectral responses [42] .…”

“…When the incident beam is in-plane and inclined at 45° with respect to the principal axis, the reflected beam shows a beamwaist ratio of ~4.25 and an ~12 dB reduction in propagation losses [42] . This type of micromirror may potentially replace lensed fibers that are widely used in MOEMS to produce monolithically integrated systems, achieving wider-band spectral responses [42] . In 2021, Kallmann et al realized an adaptive parabolic cylinder mirror using MEMS technology for the first time, in which only the long axis was deformed parabolically whereas the short axis remained flat [43] .…”