Pan Bing, Shi Wentao, Lubineau Gilles
Appl Opt. 2015 Dec 1;54(34):10089-95. doi: 10.1364/AO.54.010089.
In laboratory and especially non-laboratory stereo-digital image correlation (stereo-DIC) applications, the extrinsic and intrinsic parameters of the cameras used in the system may change slightly due to the camera warm-up effect and possible variations in ambient temperature. Because these camera parameters are generally calibrated once prior to measurements and considered to be unaltered during the whole measurement period, the changes in these parameters unavoidably induce displacement/strain errors. In this study, the effect of temperature variations on stereo-DIC measurements is investigated experimentally. To quantify the errors associated with camera or ambient temperature changes, surface displacements and strains of a stationary optical quartz glass plate with near-zero thermal expansion were continuously measured using a regular stereo-DIC system. The results confirm that (1) temperature variations in the cameras and ambient environment have a considerable influence on the displacements and strains measured by stereo-DIC due to the slightly altered extrinsic and intrinsic camera parameters; and (2) the corresponding displacement and strain errors correlate with temperature changes. For the specific stereo-DIC configuration used in this work, the temperature-induced strain errors were estimated to be approximately 30-50 με/°C. To minimize the adverse effect of camera temperature variations on stereo-DIC measurements, two simple but effective solutions are suggested.
在实验室尤其是非实验室的立体数字图像相关（stereo-DIC）应用中，系统中使用的相机的外部和内部参数可能会因相机预热效应以及环境温度的可能变化而略有改变。由于这些相机参数通常在测量前校准一次，并在整个测量期间被认为是不变的，这些参数的变化不可避免地会引起位移/应变误差。在本研究中，通过实验研究了温度变化对立体数字图像相关测量的影响。为了量化与相机或环境温度变化相关的误差，使用常规的立体数字图像相关系统连续测量了具有近零热膨胀的固定光学石英玻璃板的表面位移和应变。结果证实：（1）相机和环境温度的变化对立体数字图像相关测量的位移和应变有相当大的影响，这是由于相机的外部和内部参数略有改变；（2）相应的位移和应变误差与温度变化相关。对于本工作中使用的特定立体数字图像相关配置，温度引起的应变误差估计约为30 - 50 με/°C。为了最小化相机温度变化对立体数字图像相关测量的不利影响，提出了两种简单但有效的解决方案。
