一种新的红外脉冲热成像后处理方法

A NEW POST-PROCESSING METHOD FOR INFRARED PULSE THERMOGRAPHY

脉冲热成像技术作为一种新兴的无损检测技术已被广泛应用于红外领域,然而由于试样表面加热不均匀及表面发射率低导致的红外图像对比度低、噪声大等问题给缺陷的检测带来困难。本文基于长脉冲热成像技术对碳纤维增强塑料(carbon fiber reinforced polymer,CFRP)板和304不锈钢进行了无损检测研究,提出了比温度的图像后处理方法。该方法对温度序列图像的每一帧图像与前一帧图像进行作商的后处理操作,得到比温度的图像序列。从比温度序列中获取信噪比最大的图像,以进行缺陷识别和缺陷定量。结果表明,与此前的方法相比,该方法显著提高了图像的信噪比,更有利于检测更深、更小的缺陷,相比原始图像,信噪比提高了近98.46%。将该方法与半高全宽法相结合,对试样的尺寸进行定量检测。通过仿真和实验验证,该方法具有良好的鲁棒性,显著降低了缺陷尺寸定量的误差,该方法可作为一种有效的红外图像后处理及缺陷尺寸定量方法。

Pulse thermography,as an emerging non-destructive testing technique,has been widely used in the infrared field.However,the low contrast and high noise in infrared images caused by uneven heating of the sample surface and low surface emissivity pose challenges for defect detection.In this study,non-destructive testing of composite materials,specifically CFRP(carbon fiber reinforced polymer)plates and 304 stainless steel,was conducted using long pulse thermography.A post-processing method based on temperature ratios was proposed.This method performs a division operation on each frame of the temperature sequence image and the previous frame image to obtain a sequence of temperature ratio images.The image with the highest signal-tonoise ratio is extracted from the temperature ratio sequence for defect identification and quantification.The results show that the method significantly improves the signal-to-noise ratio of the image compared with the previous method,and is more conducive to detecting deeper and smaller defects,compared with the original image,the signal-to-noise ratio is improved by nearly 98.46%.We combined the method with the half-height fullwidth method to quantify the size of the specimen.Through simulation and experimental verification,the method has good robustness and significantly reduces the error of defect size quantification.Therefore,this method can be considered as an effective infrared image post-processing and defect size quantification method.