Inspection of metal and concrete specimens using imaging system with laser displacement sensor

Flaws such as cracks and impact damages initially occur on the surface of the infrastructure materials and propagate internally causing further degradation. These infrastructure materials have different physical and chemical composition and have different geometric shapes, which can mask the indication of minute surface flaws. There is a need to develop systems that can detect these surface flaws irrespective of their properties and shapes. We propose an imaging system capable of interrogating plain and non-plain structures for the purpose of detection and evaluation of surface flaws such as cracks and impact damages using a laser displacement sensor (LDS). The developed system consists of LDS mounted on the scanner, which is capable of raster scanning over the material under test. The reading of displacement from the sensor head to the laser spot on the surface of the test material is then used to generate two-dimensional (2-D) images in real time, which can be used to detect minute surface flaws. This paper presents the results of inspection of metal and concrete test specimens. 2-D images through the cut of the metal profile are also generated to demonstrate the ability of a system to image interior structure.