点阵全息防伪标识的衍射效率测量研究

Measurement of diffraction efficiency of dot-matrix-holographic security indentifiers

提出了一种测量点阵全息图衍射效率的方法,搭建了光学系统。通过在系统光路中放置平面反射镜,巧妙地将正负一级衍射光与其他级次的衍射光分离开,使光电探测器只接收正负一级衍射光,并且这种测量方法不受被测点干涉条纹方向变化的影响;在激光器后面放置一个半透半反波片,用两个相同的光电探测器分别实时测量反射光和衍射光的功率,降低了由于激光器功率不稳定造成的测量误差,得到八种不同的点阵全息防伪标识的衍射效率的测量结果。

A measurement method of diffraction efficiency of dot-matrix holography was proposed and an optical system was built.The first order (positive and negative)diffractive beams were separated from the zero and second ones skillfully by placing a plane reflect mirror within the system optical path to make a photodetector receive the first order (positive and negative)diffractive beams only.The direction variation of interference fringe cannot affect the experiment value.A half-wave plate was placed behind the laser and the power of the reflected beams and diffractive beams were received by two same photodetectors.At last the diffraction efficiency of eight different holographic security identifiers were calculated.