Method and Apparatus for Nondestructive Sample Inspection

Technology Case 04UMR033

Technology Overview

The invention involves an apparatus and method for near-field microwave and millimeter wave nondestructive testing and evaluation of complex composite structures having a dual probe.  Two coherent microwave signals from a single source are transmitted to the dual probe transmitting these signals to the structure under inspection and receiving reflected signals from it.  A difference of the reflected signals is transmitted to a detector in order to remove or reduce influence of standoff distance variation to increase sensitivity of the system.  A type of the dual probe and its size provide increasing resolution of the system.  An electrical distance between two apertures of the dual probe is provided for reducing and removing unwanted edge effects.  Appropriate scanning and signal processing is used to provide for creating separate defect images from the dual probe and from each of its apertures to increase probability of defect detection and evaluation. 


As a way of example, the present invention may be used in inspecting a sample such as a metal plate for anomalies or defects in the form of microscopic corrosion pits, which can grow and become visible corrosion under the paint in a car, for instance. In the aircraft industry, detection of corrosion pits aid in predicting where the corrosion is going to occur. A defect such as a corrosion pit causes the signal radiated on the sample 16 to change in phase and/or magnitude. Therefore, a difference in the phase and/or magnitude of the two signals reflected from the sample indicates the presence of a defect.


Technology Benefits

  • Nondestructive testing of complex composite structures
  • Can detect many different types of defects in a variety of materials. For example, identification of corrosion and precursor pitting under paint and other thick and thin dielectric laminates
  • Detection and evaluation of cracks, debond, delamination, impact damage, localized porosity, etc.

Potential Applications

  • Removes or reduces the influence of standoff distance variation on results
  • Increased sensitivity and resolution of system
  • Removes unwanted edge effects
  • High efficiency in detecting small defects
Keith David Strassner


Office of Technology Transfer and Economic Development