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Applied Optics

Applied Optics


  • Vol. 34, Iss. 31 — Nov. 1, 1995
  • pp: 7221–7227

Liquid-crystal-based switchable polarizers for sensor protection

Chiung-Sheng Wu and Shin-Tson Wu  »View Author Affiliations

Applied Optics, Vol. 34, Issue 31, pp. 7221-7227 (1995)

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Linear polarizers are generally employed in conjunction with advanced liquid-crystal filters for the protection of human eyes and optical sensors. For detection sensitivity under a no-threat condition to be maximized, the polarizer should remain in a clear state with a minimum insertion loss. When threats are present, it should be quickly switched to function as a linear polarizer with a high extinction ratio. Two types of switchable polarizer for sensor protection are demonstrated. The polarization conversion type exhibits a high optical efficiency in its clear state, a high extinction ratio in the linear polarizer state, and a fast switching speed, except that its field of view is limited to approximately ±10°. In contrast, an improved switchable dichroic polarizer functions effectively over a much wider field of view. However, its extinction ratio and optical efficiency in its clear state are lower than those of the polarization conversion type.

© 1995 Optical Society of America

Original Manuscript: February 21, 1995
Revised Manuscript: April 21, 1995
Published: November 1, 1995

Chiung-Sheng Wu and Shin-Tson Wu, "Liquid-crystal-based switchable polarizers for sensor protection," Appl. Opt. 34, 7221-7227 (1995)

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  1. See, e.g., many of the review papers in the special issue of the International Journal of Nonlinear Optical Physics, October 1993.
  2. S. T. Wu, “Design of a liquid-crystal-based electro-optic filter,” Appl. Opt. 28, 48–52 (1989). [CrossRef] [PubMed]
  3. J. Staromlynska, “Electro-optic broad band tunable filters using liquid crystals,” J. Mod. Opt. 37, 639–652 (1990). [CrossRef]
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  5. A. Berman, “Agile notch filters,” in Proceedings of the First DoD Liquid Crystal Workshop, J. G. Theodore, ed. (U.S. Air Force Wright-Patterson Laboratory, Dayton, Ohio, 1993), pp. 47–101.
  6. G. H. Heilmeier, L. A. Zanoni, “Guest-host interactions in nematic liquid crystals,” Appl. Phys. Lett. 13, 91–93 (1968). [CrossRef]
  7. S. T. Wu, J. D. Margerum, M. S. Ho, B. M. Fung, “Liquid crystal dyes with high solubility and large dielectric anisotropy,” Appl. Phys. Lett. 64, 2191–2193 (1994). [CrossRef]
  8. Y. Fujimura, T. Nagatsuka, H. Yoshimi, T. Shimomura, “Optical properties of retardation films for STN-LCDs,” Soc. Inf. Displ., Technol. Dig. 22, 739–742 (1991).
  9. S. T. Wu, “Film-compensated homeotropic liquid-crystal cell for direct view display,” J. Appl. Phys. 76, 5975–5980 (1994). [CrossRef]
  10. See, e.g., L. Levi, Applied Optics (Wiley, New York, 1980), Vol. 2, Chap. 11.
  11. I. C. Khoo, S. T. Wu, Optics and Nonlinear Optics of Liquid Crystals (World Scientific, Singapore, 1993), Chap. 2. [CrossRef]

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