Information Encryption Based on Using Arbitrary Two-Step Phase-Shift Interferometry

A deterministic phase-encoded encryption system is proposed. A lenticular lens array (LLA) sheet with a particular LPI (lenticular per inch) number is chosen as a modulator (key) instead of the random phase molator. The suggested encryption scheme is based on arbitrary two-step phase-shift interferometry (PSI), using an unknown phase step. The encryption and decryption principle is based on an LLA in arbitrary unknown two-step PSI. Right key holograms can be used to theoretically show that the object wavefront is the only one left in the hologram plane and that all accompanying undesired terms are eliminated. The encrypted image can therefore be numerically and successfully decrypted with the right key in the image plane. The number of degrees of freedom of the encryption scheme increases with the distance from the object and the LLA to the CCD, and also with the unknown phase-step and the LLA LPI number. Computer simulations are performed to verify the encryption and decryption principles without a key, with the wrong key and with the right key. Optical experiments are also performed to validate them.

基于FPGA的双路可移相任意波形发生器

论述了利用FPGA开发DDS函数发生器的总体设计思路,讨论了任意波形产生、双路移相输出、PWM调制波产生等方面的设计方法。系统基于Altera公司的Cyclone系列FPGA,配合Atmel公司高性能AVR系列单片机实现。

利用液晶波片去除零级像的数字全息成像研究

为了减少零级干扰项对数字全息再现像的影响,本文提出了一种在参考光路中加入电控液晶波片的方法。通过电控液晶波片的延迟量引入一任意相移δ,先后记录两次全息图。使用一次任意相移法去除零级项,再对全息图中物体信息进行重建再现。实验结果表明:该方法能有效减少零级干扰项对物体再现象的影响,结合频域滤波法进一步提高了图像质量。

任意相移阴影叠栅相位解调技术的研究

结合时域和频域干涉图分析方法,提出一种任意相移阴影叠栅条纹图相位解调技术,降低了干涉图在采样过程中对相移量的严格标定要求,补偿了相移阴影叠栅技术固有的相移不匀误差。使用空域技术确定采样干涉图的正交信号,进而得到了采样干涉图的相移量,然后运用任意相移相位提取算法搜索测量相位信息。实验证明此方法简单方便、求解迅速,且优于典型的相移算法,其测量误差的标准差不超过3×10-3 mm,该方法为提高相移阴影叠栅技术的测量精度提供了有效手段。

几种任意步距步进相移算法的误差分析与对比

介绍了到目前为止的几种任意步距步进相移算法，并针对相移干涉仪的两种主要误差———移相误差和探测器非线性误差进行了计算仿真，进而比较分析了它们对这这些误差的抑制能力，其结果可为实际应用合理地选择算法提供理论依据。