Affiliations: [a] Department of Machine Intelligence and Systems
Engineering, Akita Prefectural University, Yurihonjo, Japan | [b] Institute of Fluid Science, Tohoku University, Sendai,
Japan
Correspondence:
[*]
Corresponding author: Seiichi Sudo, Department of Machine
Intelligence and Systems Engineering, Akita Prefectural University, Ebinokuchi
84-4, Yurihonjo, 015-0055, Japan. Tel.: +81 184 27 2111; Fax: +81 184 27 2188;
E-mail: sudo@akita-pu.ac.jp
Abstract: This paper is concerned with a novel optical diaphragm using
magnetic fluid and a permanent magnet. The optical diaphragm consisting of a
kerosene-based magnetic fluid and a small ring-shaped
Nd_{2}Fe_{14}B permanent magnet was
designed. The magnetic fluid diaphragm was driven by the external magnetic
field. The experimental apparatus consists of the test magnetic fluid diaphragm
system and the optical measurement system. Frequency characteristics of the
magnetic fluid diaphragm in the alternating magnetic field were studied
experimentally. The alternating magnetic field was generated by applying
alternating current voltage to a Helmholtz coil. The alternating current signal
was supplied from the frequency synthesizer. The dynamic responses of magnetic
fluid diaphragm were analyzed with a high-speed video camera system. It was
revealed that the amplitude of magnetic fluid hole oscillation depended on the
frequency of magnetic field. The effect of the applied voltage on the amplitude
of hole oscillation was also revealed.
Keywords: Magnetic fluids, optical diaphragm, interfacial phenomena, alternating magnetic field
