Abstract: A new photopolymerizable material allows single-step, fast recording of volume holograms with properties that can be electrically controlled. Polymer-dispersed liquid crystals (PDLCs) in accordance with the invention preferably comprise a homogeneous mixture of a nematic liquid crystal and a multifunctional pentaacrylate monomer in combination with photoinitiator, coinitiator and cross-linking agent. Optionally, a surfactant such as octancic acid may also be added. The PDLC material is exposed to coherent light to produce an interference pattern inside the material. Photopolymerization of the new PDLC material produces a hologram of clearly separated liquid crystal domains and cured polymer domains.

Abstract: A new photopolymerizable material allows single-step, fast recording of volume holograms with properties that can be electrically controlled. Polymer-dispersed liquid crystals (PDLCs) in accordance with the invention preferably comprise a homogeneous mixture of a nematic liquid crystal and a multifunctional pentaacrylate monomer in combination with photoinitiator, coinitiator and cross-linking agent. Optionally, a surfactant such as octanoic acid may also be added. The PDLC material is exposed to coherent light to produce an interference pattern inside the material. Photopolymerization of the new PDLC material produces a hologram of clearly separated liquid crystal domains and cured polymer domains.

Abstract: A new photopolymerizable material allows single-step, fast recording of volume holograms with properties that can be electrically controlled. A method for preparing a switchable grating can comprise the steps of placing a mixture between a first and second slide, wherein the mixture has a photopolymerizable monomer, a second phase material, a photoinitiator dye, and a chain extender or cross-linker. The mixture is exposed to a laser and optical intensity pattern is applied to induce photopolymerization. A method for recording slanted reflection gratings can comprise the steps of placing a sample between a first and second glass prism, the sample comprising a polymerizable monomer, a liquid crystal, a chain-extending monomer, a coinitiator, and a photoinitiator. An incident light is split into two beams, wherein the beams enter the sample from opposite sides. The first and second prism are rotated to adjust the slant of the grating.

Abstract: The process described herein offers the optimizing of performance parameters of holograms, such as reducing scattering effects in a polymer-dispersed liquid crystal optical element. In the process, an interfacial tension agent is added to a polymer-dispersed liquid crystal material. The polymer-dispersed liquid crystal material has at least one acrylic acid monomer, at least one type of liquid crystal material, a photoinitiator dye, and a co-initiator. The polymer-dispersed liquid crystal material is subjected to a polymerization. The interfacial tension agent reduces the size of liquid crystal droplets formed within the polymer-dispersed liquid crystal optical element during polymerization.

Abstract: A new photopolymerizable material allows single-step, fast recording of volume holograms with properties that can be electrically controlled. Polymer-dispersed liquid crystals (PDLCs) in accordance with the invention preferably comprise a homogeneous mixture of a nematic liquid crystal and a multifunctional pentaacrylate monomer in combination with photoinitiator, coinitiator and cross-linking agent. Optionally, a surfactant such as octancic acid may also be added. The PDLC material is exposed to coherent light to produce an interference pattern inside the material. Photopolymerization of the new PDLC material produces a hologram of clearly separated liquid crystal domains and cured polymer domains. Volume transmission gratings made with the new PDLC material can be electrically switched between nearly 100% diffraction efficiency and nearly 0% diffraction efficiency. By increasing the frequency of the switching voltage, switching voltages in the range of 50 Vrms can be achieved.

Abstract: A method for preparing electro-optical polymer-liquid crystal photonic crystals, comprising: disposing between at least two optically transparent electrode plates, a polymer-dispersed liquid crystal material that comprises, before exposure: (a) a polymerizable monomer comprising at least one acrylate; (b) a liquid crystal; (c) a chain-extending monomer; (d) a coinitiator; (e) a photoinitiator; and (f) a long chain aliphatic acid; and exposing this polymer-dispersed liquid crystal material to light in an interference pattern.

Abstract: The present invention offers control over—and the ability to optimize—the performance parameters of switchable holograms. The present invention offers the ability to tailor the properties of a hologram to a desired application and thus make application-specific holograms. The invention relates to polymer-dispersed liquid crystal materials subject to control and optimization of the performance parameters of switchable holograms. Such variability allows tailoring the properties to application-specific devices. Specifically, the present invention provides an improved polymer-dispersed liquid crystal system that allows variation of: 1) haze, 2) switching voltage, 3) electrical power dissipation, 4) switching stability (voltage creep), 5) switching contrast ratio (range), 6) dynamic stability, and 7) the operating temperature range.

Abstract: A new photopolymerizable material allows single-step, fast recording of volume holograms with properties that can be electrically controlled. Polymer-dispersed liquid crystals (PDLCs) in accordance with the invention preferably comprise a homogeneous mixture of a nematic liquid crystal and a multifunctional pentaacrylate monomer in combination with photoinitiator, coinitiator and cross-linking agent. Optionally, a surfactant such as octancic acid may also be added. The PDLC material is exposed to coherent light to produce an interference pattern inside the material. Photopolymerization of the new PDLC material produces a hologram of clearly separated liquid crystal domains and cured polymer domains. Volume transmission gratings made with the new PDLC material can be electrically switched between nearly 100% diffraction efficiency and nearly 0% diffraction efficiency. By increasing the frequency of the switching voltage, switching voltages in the range of 50 Vrms can be achieved.

Abstract: A process and photoactive media for holographic recording and micro/nanofabrication of optical and bio-optical structures via the simultaneous absorption of two-photons by the photoactive media to induce a simultaneous photochemical change in regions of constructive interference within a holographic pattern is disclosed. The photochemical process of polymerization resulting from the simultaneous absorption of two-photons may be used for the microfabrication of micro and nanoscaled features, holographic data storage, and the formation of switchable diffraction gratings.

Abstract: A new personal laser dosimetry badge records intentional or unintentional exposure to laser radiation. A Fresnel biprism is mounted over a layer of photopolymerizable material, preferably a polymer-dispersed liquid crystal material. A laser beam striking the apex of the biprism splits into two beams crossing at an angle which depends on the prism apex angle and the angle of incidence. These crossed beams form an interference pattern at the photopolymer with bright and dark fringes separated by a distance which depends on wavelength and the crossing angle of the two beams. The light triggers a photopolymerization reaction in the bright regions and records a permanent refractive index modulation, a hologram, which serves as a record of the laser interference pattern. Light incident normally on the badge will produce a normal index grating. Light incident at an angle will produce a slanted grating.