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A Swing Driven by Liquid Crystals

Cheng, Cheng
http://rave.ohiolink.edu/etdc/view?acc_num=kent1460317639

Abstract Details

, PHD, Kent State University, College of Arts and Sciences / Chemical Physics.
Angular momentum in liquid crystals exists as flow, director reorientation, etc. However, it is hard to observe and measure angular momentum in liquid crystals by a direct mechanical approach. Torsion pendulum is a general tool to measure angular momentum by torque balance. Our torsion pendulum can harvest the angular momentum in liquid crystals to make it observable. The oscillation of the pendulum keeps increasing by constructively adding a small angular momentum of liquid crystals each period at the resonant frequency of the pendulum. It’s similar to a swing driven by a force at its resonant frequency. For the torsion pendulum, a cage made of two aluminum discs, in which a liquid crystal cell is placed, is suspended between two thin tungsten wires. A gold mirror, which is a part of the optical lever system, is attached on one tungsten wire. As first demonstration, we fabricate a circular hybrid liquid crystal cell, which can induce concentric backflows to generate angular momentum. The alignment on the planar substrate is concentric and tangential. Due to the coupling between director rotation and flow, the induced backflow goes around the cell when we add electrical pulses between top and bottom substrates. The oscillation is observed by a position sensitive detector and analyzed on the basis of Eriksen-Leslie theory. With vacuum condition and synchronous driving system, the oscillation signal is improved. We demonstrate that this torsion pendulum can sensitively detect the angular momentum in liquid crystals.
Hiroshi Yokoyama (Advisor)
Peter Palffy-Muhoray (Advisor)
Deng-Ke Yang (Committee Member)
235 p.
Physics

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Citations

  • Cheng, C. (2016). A Swing Driven by Liquid Crystals [Doctoral dissertation, Kent State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=kent1460317639

    APA Style (7th edition)

  • Cheng, Cheng. A Swing Driven by Liquid Crystals. 2016. Kent State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=kent1460317639.

    MLA Style (8th edition)

  • Cheng, Cheng. "A Swing Driven by Liquid Crystals." Doctoral dissertation, Kent State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=kent1460317639

    Chicago Manual of Style (17th edition)

kent1460317639
298
© 2016, all rights reserved.
This open access ETD is published by Kent State University and OhioLINK.