Certain light-emitting materials (or phosphors) are able to internally store energy for a long time.
Upon mechanical stimulation, such as pressure or scratching, some can emit this energy in the
form of visible light. These mechanoluminescent (ML) phosphors only start to show their full
application potential.
The first goal is to use these phosphors for the visualization of ultrasonic fields. Ultrasound,
defined as sound with a frequency over 20 kHz, is heavily applied in a number of fields such as
medical imaging and material testing. Determining the shape of the ultrasonic pressure field now
requires lengthy measurements, but ML phosphors offer an alternative. Sound, being a pressure
wave, can provide the mechanical stimulation needed for the emission of light. By putting a
phosphor coated disk in the ultrasound beam and photographing the emitted light, a map of the
incident ultrasound pressure can be reconstructed. In this project I will develop a prototype for a
fast 3D reconstruction of such an ultrasonic radiation pattern, with high spatial resolution.
The second goal is the detection of structural defects in materials by means of their specific
vibrational behavior. Near defects, stress in the material can locally trigger the ML emission. This
research will especially be suitable for non-destructive testing of composites, being the favorite
materials for e.g. airplanes and wind mills.
Finally, we investigate and model the physical mechanism driving the ML phenomenon