全息曝光条纹锁定研究与装置设计

The fabrication of the locking device of interference fringes in holographic exposure

全息曝光环节干涉条纹的稳定性对于潜像质量的高低有着直接的影响,进而影响掩模形貌和离子刻蚀后光栅的槽型.为了保证干涉条纹的稳定性,依据反馈控制的理论,构造闭环反馈控制回路,采用光电探测器进行误差信号(光信号)的提取,经过光-电转换,得到电信号,由于信号极其微弱,再先后通过前置放大,差动放大,积分电路,对所得误差信号进行处理,形成补偿信号,最后利用压电陶瓷进行电压-位移转换,利用转换出的位移信号对光路实施补偿.实验结果表明:该条纹锁定系统能够实时对光路稳定性进行良好的补偿控制,消除外界干扰带来的影响.

In the process of holographic exposure, the stability of interference fringes has a direct infl uence on the quality of the latent image, thus the morphology of mask and the grating groove would also be influenced when they are etched by ion beam. To improve the stability of interference fringes, according to the feedback control theory, a closed-loop negative feedback was devised. In the first step, a photoelectric detector is used to acquire the error signal which is optical. Then, after a light-electricity conversion, the error signal is converted to an electrical one. Since the signal is extremely weak, it has to go through preamplification, differential amplification and integral circuit successively to form a compensation signal. In the last step, the piezoelectric transducer completes an electric-displacement conversfon, after which, the displacement signal can be used in the compensation of the light path. The experimental results show that the fringe locking system is able to offer an effective compensation to enhance the real-time stability of the light path, through which, the external interference can be greatly reduced in the production of grating.