Duncan D D, Kirkpatrick S J, Mark F F, Hunter L W
Appl Opt. 1994 Aug 1;33(22):5177-86. doi: 10.1364/AO.33.005177.
We have developed a highly sensitive method for measuring thermal expansion, mechanical strain, and creep rates. We use the well-known technique of observing laser speckle with a pair of linear array cameras, but we employ a data-processing approach based on a two-dimensional transform of the speckle histories from each camera. This technique can effect large gauge sizes, which are important in the assessment of the spatial statistics of creep. Further, the algorithm provides simultaneous global estimates of the strain rates at both small- and large-scale sizes. This feature may be of value in the investigation of materials with different short- and long-range orders. General advantages of our technique are compact design, modest resolution requirements, insensitivity to slow surface microstructure changes (as seen with oxidation), and insensitivity to zero-mean-noise processes such as turbulence and vibration. Herein we detail the theory of our technique and the results of a number of experiments. Thesetests are intended to demonstrate the performance advantages and limitations of the transform method of processing speckle strain-rate data.
我们开发了一种用于测量热膨胀、机械应变和蠕变率的高灵敏度方法。我们采用了用一对线性阵列相机观察激光散斑的知名技术，但我们采用了一种基于对每个相机散斑历史进行二维变换的数据处理方法。该技术可以实现大尺寸测量，这在评估蠕变的空间统计中很重要。此外，该算法能同时对小尺寸和大尺寸的应变率进行全局估计。这一特性在研究具有不同短程和长程有序的材料时可能具有价值。我们技术的总体优势包括设计紧凑、分辨率要求适中、对缓慢的表面微观结构变化（如氧化）不敏感，以及对诸如湍流和振动等零均值噪声过程不敏感。在此我们详细阐述我们技术的理论以及一些实验结果。这些测试旨在证明处理散斑应变率数据的变换方法的性能优势和局限性。
