Preparation of Dicheomated Gelatin Film for Hologram

• Main Authors: Cha, Liang-Chun, 查良駿
• Other Authors: Chi Wang
• Format: Others
• Language: zh-TW
• Online Access: http://ndltd.ncl.edu.tw/handle/24785573149879735126

碩士 === 元智工學院 === 化學工程學系 === 84 === Dichromated gelatin film (DCG film) is one of the best materials for thefabrication of holographic optical elements because of its low scattering,large refraction index modulation capacity, moderate exposure level, high resolution capacity and easy hologram thickness control. However, the filmpreparation is the most important step in holographic fabrication. In thisstudy, DCG films of about 24um on glass plates was prepared using a "doctorblade" coating method. By controlling the drying conditions in a small dust-free room, DCG films with different microstructure were developed. Firstly,TGA was used to investigate the degradation and water content of the DCG films. Secondly, DSC was applied to reveal the possible crystallinity in thefilms, when the drying was carried out at room temperature. Thirdly, the photo-induced crosslinking of Cr+3 with gelatin molecules was studied with aUV method. Fourthly, the swelling phenomena of DCG was investigated with aCCD equipped with microscopic lens. We found that water vapor is rather critical to the hologram formation ofgood quality. The diffraction efficiency is dependent on the level of exposure and the uniformity of the DCG films. In order to protect the grating after development, a thin layer of siliconerubber was put on the top of the DCG films by a Spin-coating method. Thus, theabsorption of the water vapor was reduced.