Non-Lithographic Photo-Induced Patterning of Polymers from Liquid Crystal Solvent with Spatially Modulated Director Fields
Abstract: Electro-optic properties of such composite materials as mixtures of polymers and liquid crystals (LCs) have been shown to be of practical use as elements of various optical devices. Depending on a polymer concentration in a mixture, three different types of devices were demonstrated. In the case when the concentration of a polymer significantly exceeds that of the LC, the polymer dispersed liquid crystal type of device is realized. In the opposite situation, when the concentration of the polymer is significantly lower than that of the LC, a polymer stabilized type of device is realized, where the LC is mixed with a pre-polymer, which is then polymerized. In the intermediate situation, when concentrations of a polymer and a LC are roughly of the same order of magnitude, it is possible using either a holographic two-beam recording technique or phase-separation under applied high-voltage electric field to directionally separate the polymer and the LC. In former case, a spatially inhomogeneous light intensity forces component to separate, diffuse, and form micro-structures. In the latter case, these processes are brought about by an electric voltage applied to patterned electrodes.
The invention can be used in manufacturing of optical elements such as spatial light modulators, diffractive gratings, light deflectors, and beam steering devices.
The technique of this patent has several advantages over existing compensation film manufacturing techniques. The process is simple, reproducible and yields defect-free films. The process provides much more flexibility in the tailoring of film optical properties than existing techniques. Films with different optic axis orientations can be easily realized with minor process variations. Tilted biaxial as well as uniaxial structures can be fabricated by this technique.
Patent Status: Issued U.S. Patent No. 6,822,713
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