title: Electrically controllable Fresnel lens in 90° twisted nematic liquid crystals.
abstract: This study presents a theoretical analysis and experimental demonstration of an electrically controllable Fresnel lens in a 90° twisted nematic liquid crystal cell. The cell gap was chosen to satisfy the Gooch-Tarry conditions, and therefore, the polarization rotation effect was valid regardless of the incident polarization direction. The polarization sensitivity of the diffraction efficiency of the 90° twisted nematic Fresnel lens was dependent on the applied voltage regime. Theoretical calculations effectively explain the experimental results.
authors.forename: Chie-Tong
authors.initials: CT
authors.lastname: Kuo
authors.forename: Chien-Yu
authors.initials: CY
authors.lastname: Li
authors.forename: Shih-Hung
authors.initials: SH
authors.lastname: Lin
authors.forename: Hui-Chen
authors.initials: HC
authors.lastname: Yeh