Mulaveesala Ravibabu, Vaddi Jyani Somayajulu, Singh Pushpraj
Electronics and Communication Engineering Group, PDPM-Indian Institute of Information Technology Design and Manufacturing, Jabalpur, IT Bhavan, GEC Campus, Gokalpur, Jabalpur 482011, India.
Rev Sci Instrum. 2008 Sep;79(9):094901. doi: 10.1063/1.2976673.
Infrared thermography is a whole field, noncontact, and nondestructive characterization technique widely used for the investigation of subsurface features in various solid materials (conductors, semiconductors, and composites). Increased demand for greater subsurface probing in thermal nondestructive testing is often thwarted by the probing high peak power into the sample, for which narrow pulse operation is usually used. The technique of pulse compression offers a means of increasing the average power available to illuminate test specimen without any loss of the depth resolution needed for the tactical requirements. This is accomplished by transmitting a wide pulse in which the incident heat flux is frequency modulated and then, by proper signal processing methods, causing a time compression of the received signal to a much narrower pulse of high effective peak power. For the demonstration, a mild steel sample having flat bottom holes at various depths is introduced and detection capability of the proposed approach has been studied.
红外热成像技术是一种全场、非接触且无损的表征技术，广泛应用于各种固体材料（导体、半导体和复合材料）中地下特征的研究。在热无损检测中，对更大深度探测的需求不断增加，但由于向样品输入的高峰值功率，这一需求常常受到阻碍，为此通常采用窄脉冲操作。脉冲压缩技术提供了一种增加可用于照射测试样品的平均功率的方法，而不会损失战术要求所需的深度分辨率。这是通过发射一个宽脉冲来实现的，在该宽脉冲中，入射热通量被调频，然后通过适当的信号处理方法，使接收到的信号在时间上压缩为一个有效峰值功率更高的窄得多的脉冲。为了进行演示，引入了一个在不同深度有平底孔的低碳钢样品，并研究了所提出方法的检测能力。
