激光偏振编码制导中铌酸锂晶体编码技术研究

Study on Encoding Using LiNbO_3 Crystal in Laser Polarization Encoding Guidance

针对激光驾束制导系统光束能量调制方式的原理缺陷,讨论了用铌酸锂晶体的电光效应实现空间偏振编码的原理。对铌酸锂晶体的电光效应进行了理论分析,在此基础上设计了基于普科尔效应的空间偏振编码调制器。确定了X轴方向加电场的最佳运用方式,使得经过编码器后的线偏振光具有理想的偏振态梯度分布。对接收数据处理方式进行了讨论,得到了差和比方式对旋转不敏感的结论。在实验室中用可见光进行了近场实验,获得了从最上方近似右旋圆偏振光到中间的线偏振光再到最下方的左旋圆偏振光的偏振态分布。实验曲线表明获得了与理论计算基本一致的结果。

In order to solve the theoretical limitation of laser beam energy modulating commonly applied in existing laser beam-rider guidance system, the principle of realization of space polarization encoding and decoding using lithium niobate （LiNbO3） crystal for its electrooptic effect is studied. The electrooptic effect of LiNbO3 crystal is analyzed, based on which a modulator used in space polarization encoding system is designed. And applying the electric field in X direction is found to be the best means to make linear polarization have an expected polarization gradient distribution after passing encoder. Discussion of received data processing way proves that the difference over sum method is independent of rotation. Near field experiments using visible light in laboratory have got polarization states varying through approximately right-handed circular polarization on the top of the beam to the linear polarization at the center of the beam and then to left-handed circular polarization at the bottom of the beam. The curves of experiments show that experimental results accord with theoretical calculation basically.