散斑干涉相关条纹的交叉熵表征方法

Representation Method of Correlation Fringe in Speckle Pattern Interferometry Based on Cross-Entropy

为了避免数字散斑干涉计量中传统相关条纹表征方法因散斑噪声严重导致信噪比较低的问题,根据交叉熵的基本概念和对散斑干涉计量过程状态变化信息表征基本原理的分析,提出了一种新的相关条纹图生成方法———交叉熵法.理论推导和应用效果的定量分析表明:交叉熵方法所产生的相关条纹与减条纹本质上是一致的;由于交叉熵条纹表征方法融入了自适应同态滤波,与减条纹相比具有更好的条纹图对比度、较低的散斑指数和更好的包裹相位信息提取质量.

The correlation fringes obtained by traditional methods in digital speckle pattern interferometry are se- verely contaminated by speckle noise, which results in a low signal-to-noise ratio in fringes. To overcome this di- sadvantage, a novel approach to the generation of correlation fringes based on cross-entropy is presented by taking into account the concept of cross-entropy and the basic principles of fringes representation for the state change in digital speckle pattern interferometry. The quantitative results of theoretical deduction and practical applications in- dicate that the correlation fringes obtained by the proposed method are essentially coincident with the subtraction fringes, and that, due to the integration of adaptive homomorphic filtering into the generation of cross-entropy frin- ges, the proposed approach may result in higher fringe contrast, smaller speckle index and better quality of wrapped phase map.