光折变全息CO_2激光局域热固定

Local Thermal Fixing of Photorefractive LiNbO 3 Hologram by CO 2 Laser

提出用ＣＯ２激光对记录于ＬｉＮｂＯ３晶体中的全息进行实时实地地局域热固定。通过脉冲加热和加载吸热体，可以使得温度范围在１００～２００℃之间的区域接近于加热光的形状，分布于一局部范围。文中给出了加热模型及其数值解。通过得到的最优解参数进行了一系列实验。实验结果显示，用ＣＯ２激光可以成功地对光折变全息进行实时实地地局域热固定，并且加热时间短、固定转换效率较高。

An real time and in situ fixing method by heating with a CO 2 laser beam is suggested to thermally fix a small local hologram in a bulk of Fe:LiNbO 3 photorefractive crystal. To form a heating up to 100￣200℃ volume with the shape similar to the heat transfer equations, different heating modes with or without metal absorbers for heat guiding by using a continuos or pulsed laser beam are analyzed. The optimal mode may be the case of pulsed heating with absorbers. On this basis, experiments are designed and demonstrated. It is shown that the fixing process by CO 2 laser beam is very short compared with the process by oven, and the fixing efficiency is high.