NEW DEVELOPMENTS OF MICROWAVE NEAR-FIELD IMAGING WITH OPEN-ENDED WAVEGUIDES

Abstract The general aim of nondestructive testing is the detection of critical flaws without affecting the quality of intact components. Ultrasonic inspection is a very popular method; however, it requires direct contact with the object. Of particular interest are those methods which do not require any mechanical contact with the inspected component. This advantage is highly appreciated for X-rays. Basically the same should be true for other electromagnetic waves that interact with materials, e.g. for microwaves. Microwaves are transmitted through many nonmetals and hence can be used to reveal imperfections and to image them in a raster-like fashion. The purpose of this paper is to give some examples how microwaves can be applied to characterise materials or flaws. We will show the characterisation of fields in the near zone of waveguides by using lockin-thermography to improve resolution. Moreover, we present a low cost sensor technique to obtain phase- and magnitude images which provide further information.