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  • 2000-2004  (2)
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  • 1
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    Digital Beam Steering Device Based on Decoupled Birefringent Prism Deflector and Polarization Rotator (2004)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: We describe digital beam deflectors (DBDs) based on liquid crystals. Each stage of the device comprises a polarization rotator and a birefringent prism deflector. The birefringent prism deflects the beam by an angle that depends on polarization of the incident beam. The prism can be made of the uniaxial smectic A (SmA) liquid crystal (LC) or a solid crystal such as yttrium orthovanadate (YVO4). SmA prisms have high birefringence and can be constructed in a variety of shapes, including single prisms and prismatic blazed gratings of different angles and profiles. We address the challenges of uniform alignment of SmA, such as elimination of focal conic domains. Rotation of linear polarization is achieved by an electrically switched twisted nematic (TN) cell. A DBD composed of N rotator-deflector pairs steers the beam into 2(sup N) directions. As an example, we describe a four-stage DBD deflecting normally incident laser beam within the range of +/- 56 mrad with 8 mrad steps. Redirection of the beam is achieved by switching the TN cells.
    Keywords: Nuclear Physics
    Type: NASA/TM-2004-213197 , E-14696
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    Wide Angle Liquid Crystal Optical Phased Array (2004)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Accurate modeling of a high resolution, liquid crystal (LC) based, optical phased array (OPA) is shown. The simulation shows excellent agreement with a test 2-D LC OPA. The modeling method is extendable to cases where the array element size is close to the wavelength of light. The fringing fields of such a device are first studied, and subsequently reduced. This results in a device that demonstrates plus or minus 7.4 degrees of continuous beam steering at a wavelength of 1550 nm, and a diffraction efficiency (DE) higher than 72%.
    Keywords: Optics
    Type: E-14794 , Optical Society of America Annual Meeting; Oct 10, 2004 - Oct 14, 2004; Rochester, NY; United States
    Format: text
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    NASA TECHNICAL REPORTS
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