Recently, we proposed an inexpensive deformable mirror made of Poly-Vinylidene Fluoride-(PVDF), called Vibrating Membrane Mirror (VMM), to compensate for optical atmospheric aberrations [1, 2]. The degree of similarity between the vibration mode shapes of a circular membrane and Zernike polynomials were investigated and VMM was introduced as a promising alternative to the traditional deformable mirrors. The present work deals with technical concepts, design, and surface analysis of the proposed deformable mirror. The mode identification, dynamic range, and time response of the proposed mirror is discussed and important factors that influence these parameters are investigated. To measure the mirror surface motion, a Laser Doppler vibrometer is used. Results show that the mechanical performance of the VMM satisfies the basic requirements of an optical deformable mirror. The mirror performance is optically examined in an interferometer setup and recommendations are provided to improve it.
A novel vibrating membrane mirror (VMM) based on the mechanical concepts of vibrating membranes is proposed. This mirror has the capability of being a proper alternative for the traditional optical mirrors. A finite element model of membrane mirror is developed using ANSYS Workbench and its dynamic characteristics extracted to compare with main wavefront aberrations. The similarities between normal modes of a vibrating membrane and Zernike polynomials, which approximate mathematically distorted wavefront, are investigated and the degree of similarities is calculated using RMSE criteria and effective radius. To eliminate unwelcome vibrations of actuators, the excitation ring has been introduced.