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|Type of Document
||Digital light processing system based large-scale, multi-domain photoalignment technique and its applications|
|Date of Defense
dye-doped liquid crystal
||In this study, a fast and multi-domain photo-alignment technique based on DLP (Digital Light Processing) system was demonstrated using Methyl Red doped liquid crystal films. Such a technique can be applied to pattern customized large-scale images.|
Complex photo-alignment images are usually patterned using a uniform light source together with a photomask. However, it is complicated and expensive to produce photomasks. By contrary, the DMD (Digital Micro-mirror Device) chip inside the DLP projector can act as an active photomask to control the output brightness of each pixel. In the photo-alignment process, the image was sent from the computer to the DLP system and subsequently projected onto a Methyl Red doped sample. Processing the output polarization of the system allows for the photo-aligned samples to present gray-scale images under crossed polarizers.
In the experiments, samples were photo-aligned in the twisted nematic (TN) states. This work investigated the influence of the substrate materials contacting the liquid crystal, exposure time, dye concentration and light intensity on the performance of the photo-alignment. Optical paths were designed to pattern images with different sizes. This technique has great potential to be applied in fabricating security cards, gratings and other optically addressable devices. Besides high resolution, the capacity of being rewritten also expands its applicability.
||Andy Y.G. Fuh - chair|
Wei Lee - co-chair
Kuang-Yao Lo - co-chair
Chi-Yen Huang - co-chair
Tsung-Hsien Lin - advisor
Indicate in-campus at 99 year and off-campus access at 99 year.|
|Date of Submission