Transparent Phase Images in Photoactivated Liquid Crystals

Abstract

Photoactivated electric field effects in nematic liquid crystals serve as reversible nearly real-time techniques for recording phase-type holograms. In a sandwich-type cell, a photoconductive coating separates one conductive electrode from the liquid-crystal layer, which is operated below the threshold voltage for dynamic scattering. In CdS cells, transient first-order diffraction efficiencies of 10–30% are obtained within 0.1–0.2 sec from visible light exposures of less than 1 μJ/cm2. A 10-μW/cm2 Ar-ion laser interference pattern of 40 cycle/mm produced a steady-state first-order diffraction efficiency of 8% in a 13-μm thickness of MBBA in a cell operated at 4-V dc. Resolutions up to 100 cycle/mm are observed for this thickness of liquid crystal.

Analog electro-optical interface for spectral analysis

“…In these photoconductor-electro optic medium sandwiches, the electro-optical medium can be a K. D*. P. crystal [3], a P. L. Z. T. ceramic [4], or a nematic liquid crystal used in its dynamic scattering mode [5,6]. Such photosensitive-electro-optic materials as bismuth silicate (Bi12Si020) [7,8] have recently led to very impressive displays.…”

Technische Anwendungen flüssiger Kristalle

“…So erreicht man, daB die Spannung nur an den UV-belichteten Stellen wirksam wird und das erzeugte Bild projiziert werden kann, wenn der Photoleiter gegen sichtbares Licht unempfindlich ist. Die bisher mitgeteilten Versuche galten meist der erzielbaren Auflosung [95] ; so kann ein Gittermuster rnit 500 Linien/mm noch aufgelost werden. Ein Schichtenauf bau mit nematischen Fliissigkristallen wurde als Speicher fur Raumhologramme vorgeschlagen [96].…”

Enhanced Photorefractive and Third-Order Nonlinear Optical Properties of 5CB-Based Polymer-Dispersed Liquid Crystals by Graphene Doping

“…Therefore, their nonlinear and photorefractive properties are closely related to the molecular alignment of LCs. Improved diffraction efficiencies and electro-optic effects by doping nanoparticles, such as CdSe, − CdS, , dye, , and gold nanoparticles, , have already been realized in recent years. Graphene has higher electric conductivity, better geometric morphology for LC molecular alignments, and lattice matching to alkyl chains, − making graphene the most suitable candidate among all the other doping components.…”