Numerical Simulations of a Monomorph Deformable Mirror in ANSYS Software
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APTIVE AND INTEGRAL OPTICS
Numerical Simulations of a Monomorph Deformable Mirror in ANSYS Software D. A. Yagnyatinskiya, * and V. N. Fedoseyeva, ** a
LUCH Research and Production Association, Research and Developement Institute, Podolsk, Moscow oblast, 142103 Russia *e-mail: [email protected] **e-mail: [email protected] Received January 16, 2020; revised January 16, 2020; accepted January 23, 2020
Abstract—Based on the numerical simulations in ANSYS software the design of a monomorph (unimorph) deformable mirror has been developed. The control electrodes pattern, which allows reproducing aberrations up to 5th order (the first 21 Zernike modes) on the light aperture with high fidelity, was chosen. All important characteristics of the monomorph mirror were simulated: electrode-influence functions, errors in the reproduction of given aberrations, gravitational sag of the mirror, mirror surface deformations due to ambient temperature changes, thermal deformations and thermal field due to the incident laser beam, and natural frequencies of the mirror. The results prove a high efficiency of this mirror as an element of adaptive optics systems. Keywords: monomorph deformable mirror, numerical simulations, ANSYS software, aberrations, influence functions, thermal deformations, natural frequencies DOI: 10.1134/S1024856020040193
INTRODUCTION Among the variety of types of designs of deformable mirrors for adaptive optics, bimorph mirrors, with a number of advantages for use in some problems, occupy an important place. The principle of operation of mirrors of this type is based on the inverse transverse piezoelectric effect. The name “bimorph mirrors” is quite common, their following main varieties exist: classical (semipassive) bimorph, symmetric bimorph, cooperative bimorph and monomorph (unimorph) mirrors [1]. It is believed that these mirrors are well suited to compensate for wavefront distortions determined by the Kolmogorov model of a turbulent atmosphere. The spatial distribution of the wavefront distortions in this model is such that at low frequencies their magnitude changes according to the law f −11/6 [2], i.e., almost inversely proportional to the frequency squared. And for bimorph mirrors, the transverse deformations of the mirror surface depend on the spatial frequency as [2]:
w 12 . f This means that such a mirror is in good agreement with the Kolmogorov model of turbulence [3]. In this paper, we consider the simulations of a monomorph deformable mirror. It is such mirrors that have recently become widespread [4–6] due to unique characteristics and low cost. Monomorph and classical
bimorph deformable mirrors are often used in adaptive woofer-tweeter systems as a woofer element [5, 7] for correction of low-order (2–4) aberrations. These mirrors find their application in intra-cavity control of laser radiation [8], in particular for high-power cw lasers [9], as well as for focusing radiation from high-power pulsed lasers [10]. In addition, they are used in various astronomical optical systems and telescopes [11
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