利用两种响应时间不同的光折变晶体实现仅对物体变化部分成像

Novelty filtering imaging with two photorefractive crystals greatly different in resopnse times

用两种响应时间相差很大的光折变晶体Ce:SBN和Fe:LiNbO_3作为相位共轭麦克尔逊干涉仪的两个相位共轭镜,得到同一物体的两个有时间差的相位共轭像,再对这两个像做实时“异或”运算,就能实现仅对物体随时间变化部分的成像.这种方法可以大大增加两相位共轭镜的响应时间差,具有最小可探测速度低,输出信号强、输出保持时间长的优点.文中对此作了理论分析,并提供了该系统对真实物体成像的实验结果.

We present a method to implement novelty filtering and motion detection with two photorefractive crystals greatly different in response times as the two PCMs of a phase conjugate Michelson interferometer. Because this arrangement allows different combinations of crystals, the difference between the response times of the two arms can be very large and highly tunable, therefore the minimum detectable velocity of the moving object is significantly reduced and a strong and lasting image of the displaced object is obtained. We also report a method to equalize the phases and amplitudes of the phase conjugate waves from two crystals. Theoretical analysis of the relationship between the changing object and the output and experimental results are given.