Science Applications International Corporation

Christina K Shepherd

Richard L Sutherland

Donna M Brandelik

Robert T Pogue

Lalgudi V Natarajan

Stephen A Siwecki

Lalgudl V Natarajan

John Sappington

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

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

Device and method for detection and identification of biological agents

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.

The present invention offers control over&#x2014;and the ability to optimize&#x2014;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.

The present invention offers increased efficiency and quality in the duplication of a master hologram utilizing an improved method of contact printing. This improved method of contact printing employs a polymer-dispersed liquid crystal (PDLC) recording medium as the duplication blank and/or the master hologram material. The optical qualities of the PDLC material described herein provide an improved method of duplication using single beam contact printing regardless of the material comprising the master hologram. Thus, master holograms originally recorded using highly complex optical geometries (e.g., computer generated holograms) are capable of duplication without the need for multiple beam power/intensity balancing and long recording times. The improved hologram contact printing method described herein works with virtually any type of master hologram, including both reflection and transmission holograms.

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Beavercreek, OH, United States of America

Christina K Shepherd