Mechanical vibration of freely suspended ferroelectric liquid-crystal film excited by sound and electric field

Abstract

A study of the mechanical vibrations of a freely suspended (FS) ferroelectric liquid-crystal film has been carried out. Upon excitations by sound irradiation and also by electric-field application, the mechanical vibration of the FS film of the ferroelectric liquid crystal is effectively excited. In the frequency dependence, resonance vibrations are observed for both excitations and the resonance frequencies, and light reflection patterns are found to be different for both excitations, suggesting the different oscillating modes of the FS film for both excitations. In electric-field excitation, the vibration mode, which is consistent with the molecular model of the origin of the vibration due to the reorientation of Ps by Ps⋅E torque is found. In addition, the application of the FS film of the ferroelectric liquid crystal as sensitive acoustic sensors is proposed.

Nonlinear generation of vorticity in thin smectic films

“…One can think about sound as the pumping source, the corresponding experimental technique is described in Ref. [11]. It is well known that the air around the soap film considerably changes its dynamics.…”

“…(10,11) correspond to the potential part of the velocity, while the second terms belong to its solenoidal part. Further we assume that the air viscous term is weak in comparison with the frequency ω of the external force, that is…”

Optomechanical effect in ferroelectric liquid crystal freely suspended films

“…[1][2][3][4][5] Such a film is considered as perfect membrane, whose vibrational motion depends only on the film geometry, isotropic surface tension and homogeneous two-dimensional density ͑including the inertia of the air moving with the film͒. [6][7][8][9] Change in any of these parameters strongly influences resonant properties of the vibrating film, for example, the pressure gauge employing freely suspended film was shown to indicate the change of air pressure by of only 0.5 Torr.…”

Ellipsometry of Molecular Reorientation in a Freely Suspended Ferroelectric Liquid Crystal Film

“…Freely suspended (FS) film of ferroelectric liquid crystal (FLC) has layered structure and thickness of the film can be varied from only two layers to more than several hundreds layers, so that freely suspended ferroelectric liquid crystal film (FSFLC) has recently been investigated as thin two-dimensional liquid crystal system [ 1-31. In addition, several interesting electrooptical properties of a thick FS film that is thicker than helical pitch has been reported [4,5]. In this article, ellipsometric study of molecular motion of the thick FS film has been carried out.…”