This paper describes a robust liquid crystal alignment layer that can be applied to the interior surfaces of a preformed cavity. In this paper, we describe a method of infusing a dye into a microcavity to produce an effective photodefinable alignment layer. Additionally, we demonstrate that after the application of a diffused RM layer, the alignment of the liquid crystal can be rendered insensitive to subsequent light exposure. In this work we make clear the effect of the RM is not stabilizing the azodye layer, but becomes the stable alignment layer. This is demonstrated by using the process described above with the additional step of realigning of the azodye layer to be perpendicular to the surface through photo-bleaching; and showing the alignment of the LC is unaffected by this process. This versatile alignment layer method, offers significant promise for new photonics applications.
An uncooled thermal imager is being developed based on a liquid crystal (LC) transducer. Without any electrical connections, the LC transducer pixels change the long-wavelength infrared (LWIR) scene directly into a visible image as opposed to an electric signal in microbolometers. The objectives are to develop an imager technology scalable to large formats (tens of megapixels) while maintaining or improving the noise equivalent temperature difference (NETD) compared to microbolometers. The present work is demonstrating that the LCs have the required performance (sensitivity, dynamic range, speed, etc.) to enable a more flexible uncooled imager. Utilizing 200-mm wafers, a process has been developed and arrays have been fabricated using aligned LCs confined in 20×20-μm cavities elevated on thermal legs. Detectors have been successfully fabricated on both silicon and fused silica wafers using less than 10 photolithographic mask steps. A breadboard camera system has been assembled to test the imagers. Various sensor configurations are described along with advantages and disadvantages of component arrangements.
Fourier-transform imaging systems can rapidly provide a great deal of information in a scene. Many applications require systems with no moving parts. One proposed approach uses birefringent crystal stages interspersed with liquid crystal cells acting as achromatic polarization rotators. Previous research has revealed that this system may have limited applicability because of severe limitations of the field-of-view for systems with large OPD. We provide a more in-depth analysis of these limitations using mostly Extended Jones Matrix simulations. We also propose a design modifications which greatly improves FOV, allowing higher resolutions to be achieved.
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