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ADVANCED UNDERSTANDING OF THE OPTICAL PROPERTIES IN PHASE COMPENSATED LIQUID CRYSTAL DEVICES

Jang, Yong-Kyu
http://rave.ohiolink.edu/etdc/view?acc_num=kent1185484614

Abstract Details

2007, PHD, Kent State University, College of Arts and Sciences / Chemical Physics.
We investigate the optical properties of liquid crystal devices whose dark states are optically compensated to give minimum transmittance. Firstly, the effect of multiple internal reflections on the extinction ratio of perfectly compensated liquid crystal devices is studied. We find the previously unexplained wavelength dependence of light leakage in an ideally compensated device is caused by the interference of the internally reflected ordinary and extraordinary waves. While these effects have not been previously made clear, they can place a limit on the performance of liquid crystal devices used as displays, optical switches and optical attenuators. Secondly, we study the off-axis light transmission characteristics of the bright state of common liquid crystal device modes. Our research shows there is an unexpected universal shape of the off-axis light transmittance in its bright state, regardless of what liquid crystal mode is used. To understand this surprising fact, we consider simple dark and bright state models in terms of phase retardation and transmittance. We also investigate the luminance and color properties of bright state common LCDs such as ECB, VA, Pi-cell, and TN modes. According to the results, the universality of the optical properties of a bright state is maintained not only in the transmittance but also in the luminance and color properties. Thirdly, we have studied the off-axis light transmission properties of the bright state in Pi-cell devices as a function of the white state director configuration. Above a critical pretilt angle or white state voltage, the light transmittance is a much stronger function of the incident angle of light. To understand the facts, we develop a model that explains this result and provides a description of the basic issues affecting the optics of these types of devices. Finally, we explore the phase compensation of the dark states in LCDs, and find that there is a limitation for the compensation of a uniaxial layer even in the most simple director configuration.
Philip Bos (Advisor)
363 p.
Physics, Optics
multi-reflection; liquid crystal; liquid crystal device; liquid crystal display; LCD; residual birefringence; Pi-cell; phase compensation; bright state; viewing angle; simple model; color shift

Recommended Citations

Citations

  • Jang, Y.-K. (2007). ADVANCED UNDERSTANDING OF THE OPTICAL PROPERTIES IN PHASE COMPENSATED LIQUID CRYSTAL DEVICES [Doctoral dissertation, Kent State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=kent1185484614

    APA Style (7th edition)

  • Jang, Yong-Kyu. ADVANCED UNDERSTANDING OF THE OPTICAL PROPERTIES IN PHASE COMPENSATED LIQUID CRYSTAL DEVICES. 2007. Kent State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=kent1185484614.

    MLA Style (8th edition)

  • Jang, Yong-Kyu. "ADVANCED UNDERSTANDING OF THE OPTICAL PROPERTIES IN PHASE COMPENSATED LIQUID CRYSTAL DEVICES." Doctoral dissertation, Kent State University, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=kent1185484614

    Chicago Manual of Style (17th edition)

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© 2007, all rights reserved.
This open access ETD is published by Kent State University and OhioLINK.