全息检测中的焦散线现象与干涉条纹的关系

在实时全息干涉计量实验中，当试件负荷甚大时，干涉条纹中会出现一些阴影区，它们在试件破裂过程中起重要作用。当负荷接近试件断裂强度时，可清晰看到并记录下阴影区的延伸、分叉、扩展直至试件破裂的过程。这些阴影区实际上就是几何光学中的焦散线现象。应用此现象可以计算应力强度因子。介绍了在寻找全息干涉条纹与应力强度因子之间关系所作的研究，导出了干涉条纹最大值与应力强度因子之间的定量关系式。从而，为使用全息法与焦散线法相结合的检测方法提供了定量计算的基础。

Caustic Phenomena in Holographic Interferometry and Its Relation with the Interference Fringes

In the experiments of real-time holographic interferometry, some dark shadow areas appear among the interference fringes. The dark shadow areas play a very important role in the fracture process. When the applied force increases near to the fracture stress, these dark areas extend in an accelerative manner and quickly leads to total rupture of the specimen. In fact, the appearing of these dark shadow areas are the phenomena of caustic in geometry optics. The shadow area is so-called shadow spot and the factor of stress intensity can be calculated by measuring the size of corresponding length of the shadow spot according to fracture mechanics theory. The research works on the relationship between interference fringes and the factor of stress intensity are introduced. The quantitative expression of this relationship has been found and introduced. It provides a basic foundation for calculating the results of the experiment in real-time holographic interferometry combine with caustic method.