Real-time dual-channel ultrasonic system for inspection of aircraft structures Brad REGEZ 1 , Goutham KIRIKERA 1 , Igor KOMSKY 1 , Bob LASSER 2 and Sridhar KRISHNASWAMY 1 Email: s-krishnaswamy@northwestern.edu 1 Center for Quality Engineering and Failure Prevention, Northwestern University, Evanston, IL 60208 2 Imperium Inc, Maryland, USA Abstract Ultrasonic inspection techniques have a proven record of applications during manufacturing and maintenance of metallic and composite aircraft structures. A-scan, B-scan, and C-scan modalities of ultrasonic imaging are deployed as independent evaluation tools by many researchers and NDI practitioners. However, modern manufacturing and maintenance procedures require real-time three-dimensional information about the condition of multi-layered structures. This kind of information can only be provided when several ultrasonic scanning modalities are combined. In this paper, we will present an integrated dual-channel system for real-time three- dimensional evaluation of large area aircraft structures. The structure to be imaged is insonified using either a piezoelectric transducer or a laser-based acoustic generator. The receiver system consists of two integrated data acquisition channels that are utilized for concurrent in-plane and in-depth real-time evaluation of structures. High resolution imaging (“horizontal”) channel with an ultrasonic CCD camera presents large (1square inch) real-time planar (X-Y plane) images of the structures while another (“vertical”) acquisition channel analyzes in-depth (Z-axis) ultrasonic scans presenting data in an A-scan format. Applications of the dual-channel real-time ultrasonic imaging system on metallic and composite aircraft structures will be presented. Keywords: ultrasonic imaging, composite structures 1. INTRODUCTION Ultrasound has been widely used as an imaging technique for nondestructive evaluation and inspection, and ultrasonic NDI methods have an impressive record of applications on metallic and composite structures. Traditional ultrasonic imaging techniques are typically point- by-point inspection systems coupled with a scanning device. In this paper we describe an ultrasonic imaging system 1 which is combined with an A-scan ultrasonic system to provide depth information in addition to large area imaging at video rates. The system provides high-resolution and easy-to-interpret images of the structure of an investigated object. The imaging system can be used on complex geometries such as curved and/or rough surfaces, it can be configured to work in either two-sided (through-transmission) or single-side (pulse-echo) inspection, and it significantly decreases the inspection time over conventional ultrasonic C-scan techniques. The following components constitute the principal parts of the imaging system: a large-area ultrasonic source and a commercially available large-area ultrasonic CCD camera. Depending on the configuration employed, the ultrasonic transducer providing the insonification for the 17th World Conference on Nondestructive Testing, 25-28 Oct 2008, Shanghai, China