"Shearography", a laser interferometry technique, enables direct observation and measurement of strain concentrations and variation of the displacement field. Shearography performed with the aid of electronic image acquisition and processing can eliminate the practical problems that have precluded the use of other laser interferometry techniques for nondestructive inspection under field conditions. Electronic Shearography (ES) is being tested as an inspection technique for detecting cracking and other sources of stress concentration in structures. The technique offers full- field inspection capability, can be performed in real time, and is easily suited to automated computer aided data analysis. The ES images, however, lack clarity due to their speckled nature, and the technique currently lacks remote detection capability. This drawback has seriously limited the scope of this technique. Using higher resolution for image acquisition and processing will alleviate this problem. A newly developed geometric filtering technique will be applied to reduce speckle noise. Additional telescopic lenses will be used to facilitate remote measurements. The combination of the hardware and software tools will result in excellent image quality that will make this ES technique acceptable for field inspection of civil engineering structures. The ES technique will then be evaluated during field inspection of bridges, in conjunction with other state of the art inspection techniques.
