The use of guided Lamb waves in nondestructive testing allows a faster and more sensitive inspection when compared with other ultrasound techniques. The process is not easy to carry on because of the multimodal and dispersive nature of guided Lamb waves. This paper explains all the procedures to image linear defects machined in an aluminum plate in detail. An angle adjustable ultrasonic transducer was used to generate the Lamb guided wave for inspection. The technique is effectively able to determine the positioning of surface and subsurface linear defects, their length and depth.