红外热波检测中热像信号重建引起的伪缺陷现象

The Phenomenon of Pseudo-Defect Caused by Thermographic Signal Reconstruction in Pulsed Thermography Testing

在脉冲热激励红外热波检测中,热像信号重建技术(TSR)常用来分析和处理试验结果。该方法的特色是可以增加热像序列的空间和时间分辨率,提高信噪比,减少数据量。同时,该方法还能消除某些伪缺陷的干扰,比如脉冲闪光灯和热像仪镜头的反射所带来的伪缺陷。但是TSR是基于对温度变化曲线进行多项式曲线拟合的,而多项式曲线拟合中,拟合阶数和数据长度对拟合结果影响较大,在某些情况下可能会产生伪缺陷。阐述了热波数据重建技术原理,并以试件表面处于热不平衡状态和表面不均匀进行试验的结果来分析由于数据重建技术所产生的伪缺陷。

In pulsed thermography testing, thermographic signal reconstruction（TSR） is used to analyze and process experimental results. The method can increase the spatial and temporal resolution of the thermographic sequence, increase signal to noise ratio, and reduce the amount of data. In addition, this method can eliminate the interference of certain pseudo-defects, such as pseudo-defects caused by the reflections of pulsed flash lamp and the camera lens. However, TSR is based on the polynomial curve fitting of temperature curve in which the polynomial order and data length influence the fitting result, and in some cases it may generate pseudo-defects in the infrared image. This article described the principle of TSR, and analyzed the pseudo-defects caused by TSR based on the experimental results that the specimen surface was in a state of thermal imbalance and non uniform surface.