We present a new imaging approach to determine porosity in carbon fibre-reinforced polymers by active thermography in the reflection mode. The infrared radiation is excited with help of a semiconductor laser. We use rectangular pulses for the excitation light – either single pulses or a sequence of a couple of pulses – and measure the succeeding temperature transients. These signals are transferred to the frequency domain by means of a discrete Laplace transformation. The evaluation of the thermal effusivity is done by a linear fitting process which gives unequivocal results with comparatively small error bars. The method is fast and robust, and the results compare well with prior experiments carried out with ultrasonic-testing, X-ray computed tomography or other approaches of thermography, where the thermal diffusivity has been determined.

我们提出了一种新的成像方法，通过反射模式下的主动热成像技术确定碳纤维增强聚合物的孔隙率。借助于半导体激光器激发红外辐射。我们对激发光使用矩形脉冲（无论是单个脉冲还是一系列脉冲序列），并测量后续的温度瞬变。这些信号通过离散的拉普拉斯变换传输到频域。热效率的评估是通过线性拟合过程完成的，该过程给出了具有相对较小误差线的明确结果。该方法快速且可靠，其结果与先前确定的热扩散率的超声测试，X射线计算机断层扫描或其他热成像方法进行的实验相比较。