Science Applications International Corporation

United States of America As Represented by the Secretary of the Air Force

Richard L Sutherland

Vince P Tondiglia

Bob Epling

Timothy J Bunning

Donna M Brandelik

Lalgudi V Natarajan

Stephen A Siwecki

William Joseph Kelly

Christina K Shepherd

Bill Hagan

Robert T Pogue

Lalquidi V Natarajan

William K Hagan

Lalqudi V Natarajan

W Wade Adams

Robert L Crane

Vincent P Tondiglia

Lalgudl V Natarajan

John Sappington

Described herein are the materials, mechanisms and procedures for optimizing various performance parameters of HPDLC optical devices in order to meet differing performance requirements. These optimization tailoring techniques include control and independent optimization of switchable HPDLC optical devices to meet the demanding requirements of anticipated applications for, inter alia, the telecommunications and display industries. These techniques include optimization of diffraction efficiency, i.e., index modulation, polarization dependence control, haze, cosmetic quality, control of response and relaxation time, voltage driving for on and off switching, and material uniformity. This control and independent optimization tailors properties of switchable HPDLC optical devices according to the specific requirements of the application of the switchable HPDLC optical device. The invention disclosed herein retains the desirable attributes of the multi-functional acrylate system for forming HPDLC optical devices, but adds new materials to the acrylate system and/or new process control to the recording to optimize performance parameters as may be needed for specific applications. This results in high optical quality switchable holograms with good diffraction efficiency and low, stable switching voltage.

Optimizing performance parameters for switchable polymer dispersed liquid crystal optical elements

Method for controlling an index modulation of a switchable polymer dispersed liquid crystal optical component

A method of sensing an environmental agent, comprising obtaining a sample from the environment and transferring the sample into the working fluid for dispensation to a detection module. The sample and working fluid mixture is filtered through a porous polymer Bragg grating. By comparing the refractive index of the grating with the mixture to the refractive index of a grating without the sample, a difference in the refractive index aids in the identification of a hazardous agent in the environment. The sensor also acts as a chemical filter by trapping specific target agents by a highly specific reaction with a conjugate molecule. Recirculation of the working fluid throughout the system provides a sensor that is 'always on.'

Detection and identification of biological agents using Bragg filters

Transmission and reflection type holograms may be formed utilizing a novel polymer-dispersed liquid crystal (PDLC) material and its unique switching characteristics to form optical elements. Applications for these switchable holograms include communications switches and switchable transmission, and reflection red, green, and blue lenses. The PDLC material offers all of the features of holographic photopolymers with the added advantage that the hologram can be switched on and off with the application of an electric field. The material is a mixture of a polymerizable monomer and liquid crystal, along with other ingredients, including a photoinitiator dye. Upon irradiation, the liquid crystal separates as a distinct phase of nanometer-size droplets aligned in periodic channels forming the hologram. The material is called a holographic polymer-dispersed liquid crystal (H-PDLC).

Switchable polymer-dispersed liquid crystal optical elements

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.

Electrically switchable polymer-dispersed liquid crystal materials including switchable optical couplers and reconfigurable optical interconnects

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. 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.

Switchable volume hologram materials and devices

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.

Electrically switchable polymer-dispersed liquid crystal materials

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 a first material selected from the group consisting of a reactive ionic material, an aromatic material, a polypyrrole, and an acrylated or methacrylated acid of the type HCCH&#x2014;(CO)O&#x2014;R&#x2014;(CO)OH, where R is a linear or branched alkyl chain. The polymer-dispersed liquid crystal material also has 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.

Tailoring material composition for optimization of application-specific switchable holograms

Transmission and reflection type holograms may be formed utilizing a novel polymer-dispersed liquid crystal (PDLC) material and its unique switching characteristics to form optical elements. Applications for these switchable holograms include communications switches and switchable transmission, and reflection red, green, and blue lenses. The PDLC material of the present invention offers all of the features of holographic photopolymers with the added advantage that the hologram can be switched on and off with the application of an electric field. The material is a mixture of a polymerizable monomer and liquid crystal, along with other ingredients, including a photoinitiator dye. Upon irradiation, the liquid crystal separates as a distinct phase of nanometer-size droplets aligned in periodic channels forming the hologram. The material is called a holographic polymer-dispersed liquid crystal (H-PDLC).

Growing community of inventors

Dayton, OH, United States of America

Richard L Sutherland